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121.
Forest Renewal British Columbia (FRBC) was created in 1994 to deliver programmes of sustainable development within the leading economic sector of the province, serving as a key element of the radical new natural resource management agenda being promoted by an interventionist provincial administration. Its funding consisted solely of the hypothecated revenues of a 'super' stumpage on timber harvesting. This paper considers the role FRBC played in helping to gain agreement to changes in provincial land use planning and forest strategy, and evaluates its effectiveness as an eco-tax recycling mechanism.  相似文献   
122.
Age, growth and maturity parameters are described for the Indo-Pacific squid Sepioteuthis lessoniana both temporally and spatially (equatorial, tropical and subtropical). Tropical squid that grew through periods of warming water temperatures grew 9% faster than squid that grew through periods of cool water temperatures. The tropical spring-hatched and equatorial squid had similar growth rates (3.24, 3.18 g/day) and these were significantly faster than the tropical summer/autumn hatched squid (2.89 g/day). The oldest squid aged was 224 days, but the majority of individuals were <200 days. Subtropical squid were larger, older and matured later than equatorial and tropical spring-hatched squid. The mean weight of subtropical squid aged between 100 and 150 days was >400 g, 85% greater than tropical and equatorial squid. Geographical differences revealed that subtropical mature winter females and males had mean ages >150 days, respectively 17% and 23% older than their tropical mature winter counterparts. Temporal differences in age at maturity were also evident with tropical winter females and males having a mean age of ~140 days, respectively 41% and 25% older than their summer counterparts. Cooler subtropical and winter tropical squid had the heaviest gonads (>15 g ovaries, >1.5 g testes) compared to summer tropical and equatorial squid. However, relative gonad investment (GSI) values of the cooler squid were significantly lower with cool subtropical and winter tropical females having GSI values <3, which was about half the value of the warmer water females. This study revealed considerable plasticity in the size-at-age of this species. The tropical population had growth parameters that fluctuated between an equatorial strategy (fast growth, small body size, and small gonads) and a subtropical strategy (large body size, slower growth, and large gonads) depending on season.  相似文献   
123.
Many annual cropping lands are being converted to perennial pasture in humid and subhumid areas of the USA as the economic, social, and environmental benefits of managed grazing become evident. Recent evidence about the positive effects of plant diversity on productivity is driving farmers towards management for more complex species mixes than were promoted historically for grazed pastures, but this emphasis has highlighted a lack of understanding about plant community management in pastures. To better understand this system we examined sources of variability in the plant community of a subhumid grassland that was subjected to combinations of disturbance (graze or burn), and amendment (nitrogen, carbon, or ambient), and native grass seeding treatments over 3 years (2004 to 2006). We estimated species cover five times during the study period and ordinated these data with nonmetric multidimensional scaling (NMS). The ordination explained 80% of the variation in the plant community data set. Variance in ordination site scores was ascribed to management (disturbance, soil amendment, and native grass seeding time), the environment (year, season within year, and block), or unexplained (residual) realms with a linear mixed-effects model. The overwhelming source of variability in the plant community (62–99%) was attributed to management. Ordination results illustrated that plant groups sorted out along management gradients: burned plots were shifted towards grasses while forbs and clovers were associated with grazed plots. We demonstrate how a community-level approach can be used to evaluate management regimes in agroecosystems. Our results indicate that disturbance and soil amendments can be used to shape plant communities in subhumid grasslands for specific agronomic and conservation goals.  相似文献   
124.
With growing urban populations and climate change, urban flooding is an important global issue, even in dryland regions. Flood risk assessments are usually used to identify vulnerable locations and populations, flooding experience patterns, or levels of concern about flooding, but rarely are all of these approaches combined. Furthermore, the social dynamics of flood concerns, exposure, and experience are underexplored. We combined geographic and survey data on household‐level measures of flood experience, concern, and exposure in Utah's urbanizing Wasatch Front. We asked: (1) Are socially vulnerable groups more likely to be exposed to flood risk? (2) How common are flooding experiences among urban residents, and how are these experiences related to sociodemographic characteristics and exposure? and (3) How concerned are urban residents about flooding, and does concern vary by exposure, flood experience, and sociodemographic characteristics? Although floodplain residents were more likely to be White and have higher incomes, respondents who were of a racial/ethnic minority, were older, had less education, and were living in floodplains were more likely to report flood experiences and concern about flooding. Flood risk management approaches need to address social as well as physical sources of vulnerability to floods and recognize social sources of variation in flood experiences and concern.  相似文献   
125.
This paper examines the flow of cadmium through the global economy, with the aim of quantifying emissions of cadmium into the environment as a result of anthropogenic activities. First, a materials balance methodology is presented as the most appropriate means of assessing cadmium emissions from a wide range of anthropogenic sources. This is then applied to the best available data, from a variety of sources, to arrive at estimated flows of cadmium. Results are presented for 10 geo-political world regions and for a range of economic activities including non-ferrous metals production, iron and steel production, combustion of fossil fuels, fertilizer manufacture and use, cement production and the manufacture, use and disposal of cadmium containing products. Initially, this analysis partitions the total flow of cadmium into three major categories: atmospheric emissions, water-borne effluents and solid or bulked waste arisings. the paper then suggests a probable further partition of the initial emissions into different environmental media.  相似文献   
126.
Lesser MR  Jackson ST 《Ecology》2012,93(5):1071-1081
The processes underlying the development of new populations are important for understanding how species colonize new territory and form viable long-term populations. Life-history-mediated processes such as Allee effects and dispersal capability may interact with climate variability and site-specific factors to govern population success and failure over extended time frames. We studied four disjunct populations of ponderosa pine in the Bighorn Basin of north-central Wyoming to examine population growth spanning more than five centuries. The study populations are separated from continuous ponderosa pine forest by distances ranging from 15 to >100 km. Strong evidence indicates that the initial colonizing individuals are still present, yielding a nearly complete record of population history. All trees in each population were aged using dendroecological techniques. The populations were all founded between 1530 and 1655 cal yr CE. All show logistic growth patterns, with initial exponential growth followed by a slowing during the mid to late 20th century. Initial population growth was slower than expectations from a logistic regression model at all four populations, but increased during the mid-18th century. Initial lags in population growth may have been due to strong Allee effects. A combination of overcoming Allee effects and a transition to favorable climate conditions may have facilitated a mid-18th century pulse in population growth rate.  相似文献   
127.
Germination tests for assessing biochar quality   总被引:8,自引:0,他引:8  
Definition, analysis, and certification of biochar quality are crucial to the agronomic acceptance of biochar. While most biochars have a positive impact on plant growth, some may have adverse effects due to the presence of phytotoxic compounds. Conversely, some biochars may have the ability to adsorb and neutralize natural phytotoxic compounds found in soil. We evaluated the effects of biochars on seedling growth and absorption of allelochemicals present in corn ( L.) residues. Corn seeds were germinated in aqueous extracts of six biochars produced from varied feedstocks, thermochemical processes, and temperatures. Percent germination and shoot and radicle lengths were evaluated at the end of the germination period. Extracts from the six biochars had no effect on percent germination; however, extracts from three biochars produced at high conversion temperatures significantly inhibited shoot growth by an average of 16% relative to deionized (DI) water. Polycyclic aromatic hydrocarbons detected in the aqueous extracts are believed to be at least partly responsible for the reduction in seedling growth. Repeated leaching of biochars before extract preparation eliminated the negative effects on seedling growth. Biochars differ significantly in their capacity to adsorb allelochemicals present in corn residues. Germination of corn seeds in extracts of corn residue showed 94% suppression of radicle growth compared to those exposed to DI water; however, incubation of corn residue extracts with leached biochar for 24 h before initiating the germination test increased radicle length 6 to 12 times compared to the corn residue extract treatments. Germination tests appear to be a reliable procedure to differentiate between effects of different types of biochar on corn seedling growth.  相似文献   
128.
Ecosystem Impacts of Geoengineering: A Review for Developing a Science Plan   总被引:1,自引:0,他引:1  
Geoengineering methods are intended to reduce climate change, which is already having demonstrable effects on ecosystem structure and functioning in some regions. Two types of geoengineering activities that have been proposed are: carbon dioxide (CO(2)) removal (CDR), which removes CO(2) from the atmosphere, and solar radiation management (SRM, or sunlight reflection methods), which reflects a small percentage of sunlight back into space to offset warming from greenhouse gases (GHGs). Current research suggests that SRM or CDR might diminish the impacts of climate change on ecosystems by reducing changes in temperature and precipitation. However, sudden cessation of SRM would exacerbate the climate effects on ecosystems, and some CDR might interfere with oceanic and terrestrial ecosystem processes. The many risks and uncertainties associated with these new kinds of purposeful perturbations to the Earth system are not well understood and require cautious and comprehensive research.  相似文献   
129.
Because of the synergistic effects which take place from the mixing of gases and particulates in ambient air, it is important that the determination of air contaminants be carried out on the sample in its native state without imposing any further chemical recombination during the analysis. Since x-ray diffraction provides a chemically passive method of analysis and yields molecular rather than elemental information, we have undertaken the siudy of, and have successfully employed crystal diffraction lines as a qualitative and quantitative means for determining such materials as lime, calcium carbonate, road salt, coke dust, and aerosol from sinter emissions as well as several other less common industrial particulates in samples obtained from dustfall as dispersed in a matrix of powdered amorphous glass. Correlative to the above investigation this method was also extended to the study of such gases as sulfur dioxide which may be selectively fixed to an active surface.  相似文献   
130.
Technology innovation is an increasingly globalized exercise with dramatic consequences for scientific and diplomatic goals alike, and requires enhanced participation and integration of scientists and science-minded diplomats within diplomatic missions to advance shared policy goals. This more general problem is addressed in the present article by focusing on recent collaborations between U.S. and German scientists, including several of the coauthors.  相似文献   
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