全文获取类型
收费全文 | 29473篇 |
免费 | 324篇 |
国内免费 | 222篇 |
专业分类
安全科学 | 831篇 |
废物处理 | 1060篇 |
环保管理 | 4034篇 |
综合类 | 4660篇 |
基础理论 | 8531篇 |
环境理论 | 21篇 |
污染及防治 | 7707篇 |
评价与监测 | 1741篇 |
社会与环境 | 1241篇 |
灾害及防治 | 193篇 |
出版年
2022年 | 179篇 |
2021年 | 179篇 |
2019年 | 214篇 |
2018年 | 387篇 |
2017年 | 379篇 |
2016年 | 554篇 |
2015年 | 489篇 |
2014年 | 678篇 |
2013年 | 2134篇 |
2012年 | 841篇 |
2011年 | 1249篇 |
2010年 | 1025篇 |
2009年 | 1032篇 |
2008年 | 1249篇 |
2007年 | 1329篇 |
2006年 | 1182篇 |
2005年 | 1006篇 |
2004年 | 1004篇 |
2003年 | 937篇 |
2002年 | 936篇 |
2001年 | 1239篇 |
2000年 | 860篇 |
1999年 | 548篇 |
1998年 | 426篇 |
1997年 | 435篇 |
1996年 | 442篇 |
1995年 | 482篇 |
1994年 | 439篇 |
1993年 | 395篇 |
1992年 | 414篇 |
1991年 | 373篇 |
1990年 | 376篇 |
1989年 | 411篇 |
1988年 | 347篇 |
1987年 | 300篇 |
1986年 | 276篇 |
1985年 | 305篇 |
1984年 | 286篇 |
1983年 | 321篇 |
1982年 | 322篇 |
1981年 | 271篇 |
1980年 | 243篇 |
1979年 | 269篇 |
1978年 | 229篇 |
1977年 | 195篇 |
1976年 | 200篇 |
1975年 | 192篇 |
1974年 | 172篇 |
1973年 | 171篇 |
1972年 | 198篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
181.
182.
183.
Soil acidification is one of the rising land degradation issues facing world agriculture. The risk of acidification is currently being assessed as part of agriculture productivity and sustainable theme. This study was conducted to produce a new vermicomposting cast as a recycling resource derived from municipal sewage sludge and waste oyster shell. The earthworm, Eisenia Andrei, was fed under different conditions. The most suitable mixture was 77:23 w/w% of sewage sludge and waste oyster shell. Powdered oyster shell (POS) sludge blend provided a stable pH, due to its buffering capacity during vermiculture because of the Ca2+ and OH? release effect. The vermicast products fulfilled the cast standards of Korea Ministry of Environment for all the parameters such as moisture content, pH, salinity, organic carbon, TKN, Phosphate, and heavy metals. Slowly released organic matter when added to soil improves the capacity of the soil to hold nutrients for plants, improve soil aeration for roots, and improves soil drainage. This product will be an addition to already-commercialized sludge vermicast as a higher value product. 相似文献
184.
185.
Ângela Guimarães Pereira Frank Raes Tiago De Sousa Pedrosa Paulo Rosa Søsser Brodersen Michael Søgaard Jørgensen Francisco Ferreira Xavier Querol John Rea 《Atmospheric environment (Oxford, England : 1994)》2009,43(33):5423-5432
For more than two decades a number of frameworks for scientific knowledge production are being proposed by science and technology researchers. They all advocate an extended involvement of non-specialists, in particular when it comes to knowledge production applicable to practical societal problems. We look to what extent these new frameworks have taken ground within a particular research community: the ACCENT Network of Excellence which coordinates European atmospheric chemistry and physics research applicable to air pollution and climate change. We did so by stimulating a debate through a “blog”, a survey and in-depth interviews with ACCENT scientists about the interaction between science, policy making and civil society, to which a great deal of ACCENT member contributed in writing or verbally. Most of them had interactions with policy makers and/or the general public, and they generally believe that interactions with spheres other than the scientific are needed. While such interactions give personal insight and satisfaction, they seem to have little impact on the goals and the practice of the scientific work itself. Extended frameworks of science production that go beyond the disciplinary mode seem to emerge at the level of individual scientists, yet they still need to find their way to the level of scientific project management. In this paper we discuss the justifications and barriers to implement a higher degree of extended knowledge integration in applied science projects such as ACCENT. It is felt that the community of atmospheric chemists and physicists is mature for such an implementation and recommendations are given to help and make this happen. 相似文献
186.
Agnieszka J. Bednarska Ryszard Laskowski 《Environmental pollution (Barking, Essex : 1987)》2009,157(5):1597-1602
The wide geographical distribution of ground beetles Pterostichus oblongopunctatus makes them very likely to be exposed to several environmental stressors at the same time. These could include both climatic stress and exposure to chemicals. Our previous studies demonstrated that the combined effect of nickel (Ni) and chlorpyrifos (CHP) was temperature (T)-dependent in adult P. oblongopunctatus. Frequently the different developmental stages of an organism are differently sensitive to single stressors, and for a number of reasons, such as differences in exposure routes, their interactions may also take different forms. Because of this, we studied the effects of the same factors on the beetle larvae. The results showed that all factors, as well as their interactions, influenced larvae survival. The synergistic effect of Ni and CPF was temperature-dependent and the effect of Ni × T interaction on the proportion of emerged imagines indicated stronger toxicity of Ni at 25 °C than at 10 °C. 相似文献
187.
T. Hara S. Trini Castelli R. Ohba C.J. Tremback 《Atmospheric environment (Oxford, England : 1994)》2009,43(24):3745-3753
This work is a contribution to a large project, aimed at the development of an advanced environmental assessment modelling system to be used in Japan. The modelling system here considered consisted of the RAMS and HYPACT coupled models. The RAMS code was modified to properly simulate local scale phenomena using a fine mesh size of 250 m. In this direction, the main aim here was to investigate the effect of the choice of the turbulence closure scheme on the dispersion of pollutants. Our modified version of the RAMS/HYPACT model chain was validated using field experiments which were carried out by the Japan Atomic Energy Research Institute (JAERI) in the area of Mt. Tsukuba (Japan). The mean flow, turbulence and concentration fields obtained using two alternative turbulence closure schemes are compared. A discussion on the different performances of the turbulence closures is presented and the influence of the closure schemes over the plume dispersion is investigated. 相似文献
188.
Guus J.M. Velders Jan Matthijsen 《Atmospheric environment (Oxford, England : 1994)》2009,43(25):3858-3866
The extent of the exceedance of the EU limit values for nitrogen dioxide (NO2) and particulate matter (PM10) concentrations within the Netherlands is expected to decrease significantly, in the coming years. Whether limit values will actually be exceeded, in the next decade, depends not only on European, national and local policies, but also on the effects of inevitable interannual meteorological fluctuations. An analysis of model calculations and measurements yields variations (1 sigma) in the annual average concentration of about 5% for NO2 and 9% for PM10, due to meteorological fluctuations. These deviations from long-term average concentrations affect assessments of future levels, set against limit values. For instance, an NO2 concentration of 39 μg m?3, estimated for a given year with long-term average meteorology, indicates that it is likely (chance >66%) that the limit value of 40 μg m?3 will not be exceeded in that particular year. At the same time, the estimation also indicates, for example, that this situation is unlikely (change <33%) to continue for three years in a row. However, with an estimated concentration of 38 μg m?3, it is likely that the limit value will not be exceeded for three years in a row. The limit value for the daily average PM10 concentration is equivalent to an annual average of about 32 μg m?3. This threshold is unlikely to be exceeded for three years in a row, when an annual average concentration of 29 μg m?3 is estimated. Interannual variations in concentrations of NO2 and PM10 are linked to large-scale meteorological fluctuations. Therefore, similar results can be expected for other European countries. 相似文献
189.
Doug P. Armstrong Elizabeth H. Parlato Barbara Egli Wendy J. Dimond Renske Kwikkel Åsa Berggren Mhairi McCready Kevin A. Parker John G. Ewen 《Conservation biology》2021,35(3):859-869
Inbreeding depression is an important long-term threat to reintroduced populations. However, the strength of inbreeding depression is difficult to estimate in wild populations because pedigree data are inevitably incomplete and because good data are needed on survival and reproduction. Predicting future population consequences is especially difficult because this also requires projecting future inbreeding levels and their impacts on long-term population dynamics, which are subject to many uncertainties. We illustrate how such projections can be derived through Bayesian state-space modeling methods based on a 26-year data set for North Island Robins (Petroica longipes) reintroduced to Tiritiri Matangi Island in 1992. We used pedigree data to model increases in the average inbreeding level (F ) over time based on kinship of possible breeding pairs and to estimate empirically Ne/N (effective/census population size). We used multiple imputation to model the unknown components of inbreeding coefficients, which allowed us to estimate effects of inbreeding on survival for all 1458 birds in the data set while modeling density dependence and environmental stochasticity. This modeling indicated that inbreeding reduced juvenile survival (1.83 lethal equivalents [SE 0.81]) and may have reduced subsequent adult survival (0.44 lethal equivalents [0.81]) but had no apparent effect on numbers of fledglings produced. Average inbreeding level increased to 0.10 (SE 0.001) as the population grew from 33 (0.3) to 160 (6) individuals over the 25 years, giving a ratio of 0.56 (0.01). Based on a model that also incorporated habitat regeneration, the population was projected to reach a maximum of 331–1144 birds (median 726) in 2130, then to begin a slow decline. Without inbreeding, the population would be expected stabilize at 887–1465 birds (median 1131). Such analysis, therefore, makes it possible to empirically derive the information needed for rational decisions about inbreeding management while accounting for multiple sources of uncertainty. 相似文献
190.
Quantifying the squeezing or stretching of fisheries as they adapt to displacement by marine reserves 下载免费PDF全文
The designation of no‐take marine reserves involves social and economic concerns due to the resulting displacement of fishing effort, when fishing rights are removed from those who traditionally fished within an area. Displacement can influence the functioning of the fishery and success of the reserve, yet levels of displacement are seldom quantified after reserve implementation and very rarely before that. We devised a simple analytical framework based on set theory to facilitate reserve placement. Implementation of the framework requires maps of fishing grounds, fishing effort, or catch per unit effort for at least 2 years. The framework quantifies the level of conflict that a reserve designation might cause in the fishing sector due to displacement and the opportunities to offset the conflict through fisher spatial mobility (i.e., ability of fishers to fish elsewhere). We also considered how the outputs of the framework can be used to identify targeted management interventions for each fishery. We applied the method in Honduras, where the largest marine protected area in Central America is being placed, for which spatial data on fishing effort were available for 6 fisheries over 3 years. The proposed closure had a greater negative impact on the shrimp and lobster scuba fisheries, which concentrated respectively 28% and 18% of their effort inside the reserve. These fisheries could not accommodate the displacement within existing fishing grounds. Both would be forced to stretch into new fishing grounds, which are available but are of unknown quality. These stakeholders will likely require compensation to offset costly exploratory fishing or to travel to fishing grounds farther away from port. 相似文献