全文获取类型
收费全文 | 19807篇 |
免费 | 2050篇 |
国内免费 | 3539篇 |
专业分类
安全科学 | 3630篇 |
废物处理 | 310篇 |
环保管理 | 3631篇 |
综合类 | 10345篇 |
基础理论 | 2097篇 |
环境理论 | 16篇 |
污染及防治 | 1203篇 |
评价与监测 | 1648篇 |
社会与环境 | 1554篇 |
灾害及防治 | 962篇 |
出版年
2024年 | 102篇 |
2023年 | 421篇 |
2022年 | 738篇 |
2021年 | 852篇 |
2020年 | 833篇 |
2019年 | 807篇 |
2018年 | 677篇 |
2017年 | 835篇 |
2016年 | 1030篇 |
2015年 | 1093篇 |
2014年 | 1036篇 |
2013年 | 1318篇 |
2012年 | 1498篇 |
2011年 | 1692篇 |
2010年 | 1082篇 |
2009年 | 1217篇 |
2008年 | 1022篇 |
2007年 | 1290篇 |
2006年 | 1135篇 |
2005年 | 914篇 |
2004年 | 726篇 |
2003年 | 690篇 |
2002年 | 616篇 |
2001年 | 504篇 |
2000年 | 439篇 |
1999年 | 410篇 |
1998年 | 310篇 |
1997年 | 297篇 |
1996年 | 243篇 |
1995年 | 221篇 |
1994年 | 242篇 |
1993年 | 169篇 |
1992年 | 122篇 |
1991年 | 101篇 |
1990年 | 73篇 |
1989年 | 53篇 |
1988年 | 71篇 |
1987年 | 40篇 |
1986年 | 38篇 |
1985年 | 36篇 |
1984年 | 29篇 |
1983年 | 20篇 |
1982年 | 48篇 |
1981年 | 38篇 |
1980年 | 43篇 |
1979年 | 49篇 |
1978年 | 32篇 |
1973年 | 22篇 |
1972年 | 28篇 |
1971年 | 32篇 |
排序方式: 共有10000条查询结果,搜索用时 41 毫秒
131.
Thomas W. May Michael J. Walther Jimmie D. Petty James F. Fairchild Jeff Lucero Mike Delvaux Jill Manring Mike Armbruster David Hartman 《Environmental monitoring and assessment》2001,72(2):179-206
The Republican River Basin of Colorado,Nebraska, and Kansas lies in a valley which contains PierreShale as part of its geological substrata. Selenium is anindigenous constituent in the shale and is readily leached intosurrounding groundwater. The Basin is heavily irrigated throughthe pumping of groundwater, some of which is selenium-contaminated, onto fields in agricultural production. Water,sediment, benthic invertebrates, and/or fish were collected from46 sites in the Basin and were analyzed for selenium to determinethe potential for food-chain bioaccumulation, dietary toxicity,and reproductive effects of selenium in biota. Resultingselenium concentrations were compared to published guidelines orbiological effects thresholds. Water from 38% of the sites (n = 18) contained selenium concentrations exceeding 5 g L-1, which is reported to be a high hazard for selenium accumulation into the planktonic food chain. An additional 12 sites (26% of the sites) contained selenium in water between 3–5 g L-1, constituting a moderate hazard. Selenium concentrations in sedimentindicated little to no hazard for selenium accumulation fromsediments into the benthic food chain. Ninety-five percent ofbenthic invertebrates collected exhibited selenium concentrationsexceeding 3 g g-1, a level reported as potentially lethal to fish and birds that consume them. Seventy-five percent of fish collected in 1997, 90% in 1998, and 64% in 1999 exceeded 4 g g-1selenium, indicating a high potential for toxicity andreproductive effects. However, examination of weight profilesof various species of collected individual fish suggestedsuccessful recruitment in spite of selenium concentrations thatexceeded published biological effects thresholds for health andreproductive success. This finding suggested that universalapplication of published guidelines for selenium may beinappropriate or at least may need refinement for systems similarto the Republican River Basin. Additional research is needed todetermine the true impact of selenium on fish and wildliferesources in the Basin. 相似文献
132.
Yu.M. Svirezhev W. von Bloh H.-J. Schellnhuber 《Environmental Modeling and Assessment》1999,4(4):287-294
A novel approach to the problem of estimating climate impact on social systems is suggested. This approach is based on a risk concept, where the notion of critical events is introduced and the probability of such events is estimated. The estimation considers both the inherent stochasticity of climatic processes and the artificial stochasticity of climate predictions due to scientific uncertainties. The method is worked out in some detail for the regional problem of crop production and the risks associated with global climate change, and illustrated by a case study (Kursk region of the FSU). In order to get local climatic characteristics (weather), a so-called statistical weather generator is used. One interesting finding is that the 3% risk level remains constant up to 1.0–1.1°C rise of mean seasonal temperature, if the variance does not change. On the other hand, the risk grows rapidly with increasing variance (even if the mean temperature rises very slowly). The risk approach is able to separate two problems: (i) assessment of global change impact, and (ii) decision making. The main task for the scientific community is to provide the politicians with different options; the choice of admissible (from the social point of view) critical events and the corresponding risk levels is the business of decision makers. 相似文献
133.
134.
用工业废水排放量预测地面水CODMn灰色方法研究 总被引:2,自引:0,他引:2
GPM(1)灰色生长曲线常被用于等距时序环境系统的分析建模、非等距摆动空间序列方面的应用尚未报道。本文研究提出了将非等距摆动空间序列经过等距化处理的GPM(1)线性回归优化建模方法采用该方法所建的非等距GPM(1)模型用于工业废水量预测地面水CODMn的实例表明,该方法简捷,方便、精度高于回归分析,有较大实用价值。 相似文献
135.
共振光散射技术是一项在普通荧光分光光度计上进行测量的光散射技术,文章简要介绍了光散射现象,共振光散射的基本原理并作了定量基础讨论,对共振光散射技术在环境分析中的应用作了初步研究。 相似文献
136.
137.
138.
A study on the orbit of air temperature movement 总被引:1,自引:0,他引:1
Zong-Chang Yang 《Environmental Modeling and Assessment》2007,12(2):131-143
In this paper, we describe an air temperature movement by mapping its time series to the polar coordinates: the value of the
time series is plotted on the radial coordinate and the time on the angular coordinate. In this way, both the yearly and daily
air temperature movements from five different locations of China are used to demonstrate that, in an intuitionistic view,
air temperature movement is neither random nor chaotic, but has its own orbit. We then propose an elliptic orbit model for
the air temperature movement. Our proposed model provides quite good results when it is applied to the evaluation of yearly
air temperature movements in eight locations in various parts of the world, and the evaluation of daily air temperature movements
in five locations in Hunan Province of China on December 17, 2005. Results show that our approach provides a concise and helpful
model for air temperature analysis. 相似文献
139.
Land use change is an important topic in the field of global environmental change and sustainable development. Land use change
modeling has attracted substantial attention because it helps researchers understand the mechanisms of land use change and
assists regulatory bodies in formulating relevant policies. Maotiao River Basin is located in the province of Guizhou, China,
which has a developed agricultural industry in the karst mountain areas. This paper selected biophysical and social–economic
factors as independent variables, and constructed a multiple logistic regression of farmland spatial distribution probability
by random sampling. Then, by using GIS technology and integrating the 2000 data, this study predicted the farmland spatial
pattern. When the predicted map was compared with the actual farmland map for 2000, we noted that 71% of the simulation is
in accordance with the 2000 farmland pattern. The result satisfactorily proves the reasonability and applicability of our
model. 相似文献
140.
中国水环境的NPSP问题及对策 总被引:1,自引:0,他引:1
介绍了我国水环境中的非点源污染(NonpointSourcepollution,缩写为NPSP)的情况,强调农业生产是最主要的非点源污染。同时,针对我国水污染防治的政策目标,提出一些建议。 相似文献