Base Digital Recursos Hídricos
y Cambio Climático Macaronesia

Ocean circulation, Research, Atmospheric carbon dioxide

Plankton, Ocean circulation, Efficiency, Atmosphere

Chemical hazards, Pollutant emissions, Health sciences, Environmental policy, Toxicity, Information management, Information science, Toxicology, Data management, Political science, United States environmental policy, Environmental studies, Pollutants, Public health, Political processes, Emissions policy, Toxic emissions, Environmental pollution, Government,...

Pollutant emissions, Environmental sciences, Environmental policy, Pollution control, Gas emissions, Arts, Environmental engineering, Engineering, Political science, Environmental studies, Greenhouse gas emissions, Emissions reduction, Pollutants, Civil engineering, Emissions policy, Local government, Green buildings, Architecture, Environmental pollution, G...

Pollutant emissions, Economic costs and benefits, Carbon dioxide emissions, Environmental policy, Pollution control, Environmental engineering, Engineering, Political science, Emission allowances, Emissions trading, Environmental studies, Compliance costs, Economic costs, Pollutants, Emissions reduction, Civil engineering, Political processes, Economics, Emi...

Global temperature changes, Developing countries, Environmental aspects, Research, Air quality management, Greenhouse gases, Methods, Atmospheric carbon dioxide, Deforestation, Climate change, Emissions control, Developing countries--LDCs

Agua, Contaminación, Tratamiento

Air Pollutants - analysis, United States - epidemiology, Environmental Monitoring, Public Health, Risk Assessment, Humans, Environmental Exposure - economics, Urban Health, Environmental Exposure - adverse effects, Particle Size, Particulate Matter - analysis, Epidemiological Monitoring, Particulate Matter - poisoning, Environmental Exposure - statistics & n...

Fishery economics, Law, Economic disciplines, Environmental sciences, Ecosystems, Ocean fisheries, Review, Sustainable fisheries management, Environmental studies, Agriculture, Administrative law, Economics, Natural resources, Fisheries law, Fisheries management, Social sciences, Fisheries policy, Fishery resources, Fisheries, Marine resources, Fisheries sci...

Fishery economics, Economic disciplines, Countries, Fishing equipment, Ocean fisheries, Developing countries, Political geography, Ecological economics, Hunting gear, Environmental economics, Technology, Sustainable fisheries management, Fishing industry, Environmental studies, Agriculture, Fishery collapse, Economics, Human geography, Fisheries management,...

Water, Sediment, Purification, Environment, general, The Second Songhua River, Hydrogeology, Climate Change, Environment, Fish, Waste Water Technology / Water Pollution Control / Water Management / Aquatic Pollution, Mercury, Atmospheric Protection/Air Quality Control/Air Pollution, Soil Science & Conservation, Sediments (Geology), Methylmercury, Rivers, Stu...

Vegetables, Field crops, Meats, Cereal grains, Zoology, Coarse grains, Biology, Food science, Research, Freshwater fishes, Astronomical objects, Political science, Foodstuffs, Agronomy, Food crops, Fish, Environmental studies, Agriculture, Environmental agencies, Rice, Food, Grains, Environmental pollution, Government, Social sciences, Crops, Corn, Inner pla...

Climate change, Environmental aspects, Climatic changes, Research, Models, Simulation, Wildfires, Forest & brush fires, Hypothesis testing, Biogas

Climate change, Research, Meteorology/Climatology, Earth Sciences, Impact analysis, Rivers, Climate models, Rain, Streamflow, Water flow

Investigación, Accidentes marítimos

Agua, Control de calidad, Guadiana (Cuenca)

Reutilización, Agua

Abastecimiento, Agua, Sequía, Barcelona (Área metropolitana)

Agua, Contaminación, Tratamiento

Agua, España, Calidad

Agua, Congresos y asambleas, Contaminación

España, Legislación, Agua

Fish populations, Thinning, Growth, Forecasts and trends, Sardines, Research, Anchovies, Studies, Survival analysis, Fish, Fisheries, Animal populations, Ocean-atmosphere interaction

Instalaciones sanitarias, Evaluación

humic substances, Iron complexation, pyrite, East Frisian barrier island Langeoog, nutrients, Geography, Water, Phosphates, Levees, Inorganic sulfides, Transition metals, Phosphorus compounds, Marshes, Geomorphology, Seas, Geochemistry, Wetlands, Bodies of water, Atomic physics, Sedimentary petrology, Sulfides, Engineering, Petrology, Anions, Research Papers...

Business administration, Climatology, Paleoclimatology, Astrophysics, Environmental sciences, Insolation, Summer, Solar physics, Survey research, Thermodynamics, Environmental studies, Stellar physics, Seasons, Solar radiation, Research methods, Business, Cooling, Earth sciences, Reports, Climate models, Atmospheric sciences, Proxy statements, Physics, Surve...

Geography, Water, Climatology, Geomorphology, Molecular genetics, Environmental sciences, Population studies, Biology, Animal husbandry, Bodies of water, Winter, Environmental studies, Genetics, Agriculture, Seasons, Wildlife studies, Aviculture, Population growth, Breeding, Social sciences, Animal science, Lagoons, Earth sciences, Ice, Climate models, Atmos...

Hydrology, Global Change, Precipitation, Biogeosciences, Climate variability, Atmosphere, Water/energy interactions, Water, Earth, Climate change, Geobiology

Geography, Water, Climatology, Health sciences, Physical examinations, Geomorphology, Seas, Measuring instruments, Materials science, Surface temperature, Mathematics, Mathematical functions, Oceanography, Advanced very high resolution radiometers, Medical diagnosis, Mathematical expressions, Bodies of water, Datasets, Information science, Technology, Skin t...

Geography, Climatology, Geomorphology, Seas, Environmental sciences, Ecosystems, Carbon dioxide, Biology, Food science, Respiratory physiology, Respiratory processes, Bodies of water, Foodstuffs, Plankton, Environmental studies, Phytoplankton, Physiology, Global warming, Organic foods, System physiology, Carbon compounds, Food, Oceans, Earth sciences, Marine...

Geography, Water, Temperature, Geomorphology, Seas, Environmental sciences, Biology, Bodies of water, Datasets, Biological taxonomies, Limnology, Information science, Thermodynamics, Plankton, Phytoplankton, Environmental studies, Global warming, Species, Earth sciences, Marine biology, Water temperature, Physics, Saltwater, Climate change, Hydrology, Data p...

Geography, Water, Health sciences, Climatology, Geomorphology, Environmental sciences, Tipping Elements in Earth Systems Special Feature, Carbon dioxide, Biology, Medical sciences, Electromagnetic interactions, Mechanical engineering, Machinery, Biogeochemical cycles, Bodies of water, Engineering, Nutritional science, Negative feedback, Environmental studies...

Antarctic Regions, Temperature, Algorithms, Time Factors, Ice Cover - chemistry, Greenhouse Effect, Calibration, Global temperature changes, Research, Arctic research, Methods, Sea ice, Weather, Confidence intervals, Climate change, Time series, Ice, Greenhouse gases

Population ecology, Climatology, Forests, Vegetation canopies, Carbon dioxide, Wind velocity, Summer, Montane forests, Biology, Winter, Classical mechanics, Botany, Net ecosystem exchange, Forest canopy, Environmental studies, Seasons, Vegetation structure, Carbon compounds, Fluid mechanics, Linear dynamics, Ecological modeling, Synecology, Fluid dynamics, P...

Geography, Marshes, Geomorphology, Fresh water, International relations, Estuaries, Modeling, Wetlands, Bodies of water, Limnology, Write Back, International cooperation, Political science, Topography, Salt marshes, Research methods, Geology, Earth sciences, Sea level rise, Sea level, Altimetry, Geologic processes, International politics, Land, Hydrology, Ph...

Geography, Marshes, Geomorphology, Sedimentary soils, Carbon dioxide, Electromagnetic interactions, Wetlands, Topography, Agronomy, Wetland soils, Agriculture, Soil science, Carbon compounds, Agrology, Business, Productivity, Soil chemistry, Electromagnetism, Soil chemical properties, Earth sciences, Nitrogen, Chemical compounds, Soil salinity, Physics, Elec...

Geography, Coastal landforms, Water, Marine botany, Landforms, Ecosystem dynamics, Geomorphology, Trophic levels, Herbivorous fishes, Marine fishes, Zoology, Biology, Heterotrophs, Echinoderms, Reefs, Bodies of water, Botany, Fish, Aquatic invertebrates, Agriculture, Animal feeding methods, Business, Productivity, Animal nutrition, Sea urchins, Animal scienc...

Pollutant emissions, Economic costs and benefits, Environmental policy, Pollution control, Materials, Population studies, Materials science, Marginal abatement costs, Environmental engineering, Engineering, Political science, Environmental studies, Economic costs, Pollutants, Particulate emissions, Civil engineering, Economics, Emissions policy, Environmenta...

Fruit - chemistry, Humans, Oxides - chemistry, Nutrition Policy, India, Meat, Mining, Food Analysis, Manganese - analysis, Vegetables - chemistry, Animals, Manganese - metabolism, Uranium, Cattle, Fishes, Spectrometry, X-Ray Emission, Edible Grain - chemistry, Manganese Compounds - chemistry

Investment tax credits, Economic costs and benefits, Environmental policy, Transportation, Economic policy, Production taxes, Motor vehicles, Green taxes, Carbon taxes, Public finance, Ground vehicles, Engineering, Capital costs, Political science, Tax benefits, Subsidies, Tax subsidies, Economic costs, Economics, Emissions policy, Tax credits, Hybrid vehicl...

Economic analysis, Market analysis, Dividends, Corporate taxes, Economic disciplines, Environmental policy, Consumer surplus, Political science, Electricity, United States environmental policy, Regressive taxation, Economics, Emissions policy, Income taxes, Electromagnetism, Investment returns, Government, Finance, Climate change policy, Economic research, G...

Water, Climatology, Roads, Environmental sciences, Transportation, Freight transport, Permafrost, Biology, Arts, Design, Engineering, Design engineering, Winter, Infrastructure, Environmental studies, Agriculture, Shipping, Seasons, Ice roads, Agrology, Climate change adaptation, Civil engineering, Transportation infrastructure, Soil temperature regimes, Dam...

Satellite Communications, Geographic Information Systems, Gravitation, Oceans and Seas, Environmental Monitoring - methods, Maps as Topic, Water Movements, Climatic changes, Artificial satellites, European, Planning, Research, Geodesy, Gravity, Sea level, Ocean circulation, Navigation systems, Meteorology

Water, Geography, Geomorphology, Seas, Marine fishes, Zoology, Biology, Oceanography, Bodies of water, Forum, Astronomical objects, News, Fish, Ocean currents, Oceans, Earth sciences, Ocean dynamics, Inner planets, Saltwater, Hydrology, Planets, Animals, Tuna, Ocean circulation models, Physical sciences, Biological sciences, Mercury, Astronomy, Sea water, Me...

Geography, Climatology, Paleoclimatology, Geomorphology, Environmental sciences, Materials science, Surface temperature, Biology, Modeling, Glacial processes, Bodies of water, Thermodynamics, Surface properties, Environmental studies, Global warming, Climate change adaptation, Glacial transport, Research methods, Heat index, Simulations, Oceans, Geology, Ear...

Occupational health and safety, Usage, Genetic disorders, Chlorination, Leukemia in children, Environmental health, Pesticides, Research, Health aspects, Epidemiology, Risk factors, Methods

Chemical hazards, Health sciences, Pollutant emissions, Roads, Psychology, Biochemistry, Research, Perceptual processing, Engineering, Political science, Nonmetals, Chemical mixtures, Infrastructure, Environmental studies, Biomolecules, Environmental agencies, Pollutants, Public health, Civil engineering, Transportation infrastructure, Toxic emissions, Envir...

Natural resource management, Pollutant emissions, Countries, Environmental sciences, Environmental policy, Pollution control, International relations, Developing countries, Political geography, Forest management, Environmental management, Environmental engineering, Engineering, International cooperation, Political science, Emission allowances, Environmental...

Pollutant emissions, Carbon dioxide emissions, Practical Pieces of the Energy Puzzle, Environmental policy, Carbon dioxide, Environmental economics, Thermodynamics, Engineering, Political science, Emission allowances, Electricity, Energy, Environmental studies, Pollutants, Carbon compounds, Clean energy, Emissions policy, Electromagnetism, Environmental poll...

Environmental aspects, Research, Management, Carbon sequestration, Power resources, Petroleum in submerged lands

Air Pollutants - analysis, Vehicle Emissions - toxicity, Air Pollution - prevention & control, Benzo(a)pyrene - toxicity, Risk Assessment, United States, Humans, Risk Factors, Air Pollution - adverse effects, Neoplasms - prevention & control, Environmental Exposure - adverse effects, Benzo(a)pyrene - analysis, Neoplasms - chemically induced, Threshold Limit...

Conservation of Natural Resources - trends, Air Pollution - prevention & control, Life Style, Public Policy, Humans, Greenhouse Effect, International Cooperation, Forecasting, New Zealand, Social Responsibility, Cross-Cultural Comparison, Cost-Benefit Analysis, Public Health - trends, Politics, Conservation of Natural Resources - economics, Physician's Role

Agua, Contaminación, Didáctica, Educación ambiental

Pollutant emissions, Economic costs and benefits, Environmental policy, Pollution control, Gas emissions, Price stabilization, Economic policy, Environmental engineering, Engineering, Political science, Emissions trading, Compliance costs, Environmental studies, Price ceilings, Economic costs, Greenhouse gas emissions, Emission charges, Emissions reduction,...

Pollutant emissions, Carbon dioxide emissions, Carbon pricing, Environmental policy, Pollution control, Gas emissions, Green taxes, Carbon taxes, Environmental engineering, Engineering, Atmospheric composition, Political science, Emissions trading, Environmental studies, Greenhouse gas emissions, Pollutants, Emissions reduction, Civil engineering, Meteorolog...

Climate change, Environmental policy, Emissions control, Politics, Domestic politics, Greenhouse gases, Emissions

Chemical hazards, Health sciences, Transition metals, Pollution monitoring, Oxides, Research, Chlorine compounds, Chalcogenides, Political science, Chlorides, Environmental studies, Environmental agencies, Pollutants, Public health, Environmental assessment, Environmental pollution, Air pollutants, Government, Halogen compounds, Air quality, Chemical compoun...

Geography, Coastal landforms, Water, Landforms, Geomorphology, Seas, Biota, Materials, Materials science, Biology, Beaches, Bodies of water, Digestive physiology, Ingestion, Biological taxonomies, Taxa, Environmental studies, Physiology, System physiology, Environmental pollution, Oceans, Earth sciences, Marine debris, Ocean floor, Saltwater, Waste materials...

Air Pollutants - analysis, Vehicle Emissions - toxicity, Environmental Exposure, Vehicle Emissions - analysis, Humans, Pedestrians, Research, Automobiles, Health aspects, Exhaust systems, Public aspects of medicine, Medicine, RA1-1270, Industrial medicine. Industrial hygiene, RC963-969

Labor economics, Social groups, Economic disciplines, Communities, Training devices, Materials, Human societies, Materials science, Specialized education, Industrial sectors, Industry, Mining, Training, Astronomical objects, Education, Employment, Technology, Sociology, Job performance indicators, Environmental studies, Job performance, Business, Economics,...

Dispatches, Pollution control, International relations, Sanitary engineering, Inner planets, International politics, Environmental engineering, International agreements, Engineering, Astronomical objects, Planets, International cooperation, Political science, Physical sciences, Applied sciences, Politics, Mercury, Astronomy, Civil engineering

España, Derecho, Agua, Recursos hidráulicos, Comunidad Valenciana, Gestión del agua, Planificación, Murcia (Comunidad Autónoma)

Abastecimiento, Agua, Obras hidráulicas, Madrid

Aguas residuales, Pesticidas, Análisis

España, Derecho, Agua, Derecho ambiental, Concesiones administrativas

Agua, Derecho, España, Comunidades autónomas, Gestión del agua, Conflictos constitucionales, Castilla-La Mancha

Geography, Pollutant emissions, Climatology, Geomorphology, Carbon dioxide emissions, Environmental sciences, Pollution control, Carbon dioxide, International relations, Biology, Electromagnetic interactions, Bodies of water, Environmental engineering, Engineering, Reproduction, International cooperation, Political science, Environmental studies, Pollutants,...

Thermal stress, Health sciences, Biological resistance, Intertidal zones, Congeners, Zoology, Disorders, Biology, Biopolymers, Proteins, Heat stress disorders, Biological taxonomies, Physiology and Biomechanics, Medical conditions, Littoral zones, Continuum mechanics, Polymers, Logic, Species, Heat shock proteins, Acclimatization, Earth sciences, Evolutionar...

RNA, Ribosomal, 18S - genetics, Phylogeny, Chi-Square Distribution, Sequence Analysis, DNA, Sequence Alignment, Animals, Gastropoda - classification, Ecosystem, Bayes Theorem, Polymerase Chain Reaction, Gastropoda - genetics, RNA, Ribosomal, 28S - genetics, Evolution, Molecular, Molecular evolution, Mollusks, Genetic aspects, Research

Geography, Marine botany, Climatology, Ecosystem dynamics, Geomorphology, Seas, Summer, Biology, Irradiance, Biogeochemical cycles, Bodies of water, Symbionts, Winter, Nonmetals, Botany, Environmental studies, Radiometry, Seasons, Business, Symbiosis, Productivity, Global carbon budget, Algae, Environmental biology, Earth sciences, Ecology, Atmospheric scien...

land-use, productivity, nestling, Tree Sparrow, diet, Passer montanus, invertebrates, Data collection, Birds, Animal behavior, Habitats, Food supply

Reindeer - physiology, Environmental Monitoring, Temperature, Animals, Plant Development, Ruminants - physiology, Arctic Regions, Cold Climate, Moths - physiology, Feeding Behavior, Biomass, Biodiversity, Biological research, Environmental aspects, Influence, Climatic changes, Herbivores, Research, Biology, Experimental, Ecology, QH540-549.5

Population ecology, Larvae, Ecosystem dynamics, Trophic levels, Environmental sciences, Ecosystems, Zoology, Caribous, Biology, Heterotrophs, Biomass, Developmental stages, Botany, Environmental studies, Global warming, Growth and development, Synecology, Ungulates, Developmental biology, Plant communities, Ecology, Plants, Mammals, Deer, Climate change, Tro...

Environmental aspects, Causes of, Climatic changes, Research, Ocean circulation, Carbon dioxide, Climate change, Atmospheric circulation, Models, Global warming, Ice age

Rapid ocean warming, Antarctic Circumpolar Current, Southern Ocean, Euphausia superba, Southern Annular Mode, Phytoplankton, South Georgia, Hydrology, Climate, Antarctic Oscillation, Analysis, Southern oscillation, Ocean, Ecology, Research, Summer, Oceanography, Oceans, Plankton, Ocean temperature, Ocean currents

Geography, Water, Health sciences, Blood gas analysis, Geomorphology, Ecosystems, Environmental sciences, Zoology, Carbon dioxide, Geochemistry, Biology, Medical diagnosis, Bodies of water, Hypercapnia, Medical conditions, THEME SECTION: Effects of ocean acidification on marine ecosystems, Environmental studies, Physical symptoms, Physiology, Carbon compound...

Electrophoresis, Polyacrylamide Gel, Heat-Shock Proteins - metabolism, Bivalvia - physiology, Immunoblotting, JNK Mitogen-Activated Protein Kinases - metabolism, Hot Temperature, Greece, Animals, Analysis of Variance, Ecosystem, Stress, Physiological - metabolism, Signal Transduction - physiology, Bivalvia - metabolism, p38 Mitogen-Activated Protein Kinases...

Speed, Usage, Causes of, United Kingdom, Influence, Global warming, Hurricanes, Climate models, Research, Climate change, Statistical analysis, Models, Oceanography, Ocean temperature, Meteorology

elevation, groundwater, Australia, Mangrove, sea level, Geography, Population ecology, Forests, Geomorphology, Marshes, Meteorological phenomena, Mangrove forests, Wetlands, Weather conditions, Limnology, Sedimentary petrology, Petrology, El Nino, Topography, Southern oscillation, Environmental studies, Salt marshes, Drought, Meteorology, Synecology, Geology...

Geography, Water, Geomorphology, Seas, Rayleigh waves, Materials science, Wave interaction, Elastic waves, Waves, Bodies of water, Ocean waves, Seismic waves, Amplitude, Oceans, Wave phenomena, Earth sciences, Ice, Ocean surface, Physics, Ocean floor, Microseisms, Hydrology, Surface waves, Physical sciences, Mechanics, Applied sciences, Surface science, Wave...

Human geography, Social sciences, Biology, Plants, Sea level, Altimetry, Land use, Brevia, Plant physiology, Plant growth, Botany, Physical sciences, Metrology, Biological sciences, Land development, Altitude, Water, Geologic Sediments, Oxygen, Ecosystem, Meristem - physiology, Poaceae - physiology, Poaceae - growth & development, Wetlands, Ecology, Sediment...

Core samples, Water, Geography, Climatology, Geomorphology, Continental glaciers, Antarctic regions, Glacial processes, Datasets, Ice cores, Glaciology, Information science, Engineering, Topography, Environmental studies, Astronautics, Polar regions, Research methods, Cold regions, Densification, Geology, Ice sheets, Time series, Earth sciences, Reports, Ice...

Wave climate, Southern California Bight, wave energy, coastal, Geography, Coastal landforms, Climatology, Landforms, Geomorphology, Environmental sciences, Meteorological phenomena, Waves, Bodies of water, Engineering, El Nino, Winter, Southern oscillation, Environmental studies, Seasons, Meteorology, Coasts, Oceans, Earth sciences, Climate models, Atmospher...

Geography, Water, Geomorphology, Measuring instruments, Meteorological phenomena, Estuaries, Waves, Bodies of water, Aquifers, Limnology, Hydrogeology, Groundwater, Piezometers, Technology, Environmental studies, Cyclones, Chemical properties, Meteorology, Geology, Tools, Lagoons, Earth sciences, Hurricanes, Atmospheric sciences, Saltwater, Physics, Salinity...

Pollutant emissions, Carbon dioxide emissions, Environmental policy, Environmental sciences, Pollution control, Carbon dioxide, Green taxes, Carbon taxes, Environmental engineering, Engineering, Political science, Emissions trading, Environmental studies, Emissions reduction, Pollutants, Carbon compounds, Civil engineering, Emissions policy, Environmental po...

Departments, Book Reviews, Books, Studies, Fisheries management, Research, Carbon dioxide, Biological diversity

Antarctic Regions, Models, Theoretical, History, Ancient, Atlantic Ocean, Ice Cover - chemistry, Greenhouse Effect, Seawater - chemistry, Carbon Dioxide - analysis, Water Movements, Arctic Regions, Ecosystem, Nitrous Oxide - analysis, Phytoplankton - metabolism, Greenland, Control, Ocean circulation, Environmental aspects, Influence, Climatic changes, Models...

Thermohaline circulation, Oceanography, Research, Fluid dynamics, Studies, Climate change, Models, Ocean circulation

Flowers - physiology, Flowers - growth & development, Rubiaceae - physiology, Extinction (Biology), Phylogeny, Influence, Conservation biology, Environmental aspects, Climatic changes, Research, Flowers & plants, Correlation analysis, Plant populations, Climate change, Evolutionary biology

Pollutant emissions, Financial markets, Social groups, Economic disciplines, Cogeneration, Environmental policy, Interest groups, Government services, Endowment effect, Human societies, Market mechanisms, Environmental economics, Public assistance programs, Political science, Sociology, Energy conservation, Environmental studies, Auctions, Pollutants, Enviro...

Core samples, Pollutant emissions, Health sciences, Thallium, Transition metals, Snow, Metals, Materials, Materials science, Fuels, Ice cores, Engineering, Precipitation, Toxicology, Bioaccumulation, Coal, Lead, Environmental studies, Hazardous substances, Pollutants, Public health, Research methods, Meteorology, Cadmium, Toxic emissions, Environmental pollu...

Carbon dioxide emissions, Environmental sciences, Environmental policy, Pollution control, Carbon dioxide, Biology, Environmental engineering, Engineering, Carbon trading, Political science, Emissions trading, Environmental studies, Emissions reduction, Climate change adaptation, Carbon compounds, Civil engineering, Deforestation, Emissions policy, Environme...

Fish populations, Atlantic provinces, Research, History, Hubbard, Jennifer Mary, Canadian history, Atlantic Provinces Canada, Hubbard, Jennifer, Nonfiction, Fisheries, Book reviews, Biology, Books

España, Derecho, Agua

España, Derecho, Agua, Tesis doctorales, Concesiones administrativas

Historia, Abastecimiento, Agua, Molinos de agua, Granada

España, Legislación, Agua

Legislación, Andalucía, Agua

Suelos, Agua, Contaminación, Tratamiento, Descontaminación

Agua, Calidad Simulación por ordenador