全文获取类型
收费全文 | 16931篇 |
免费 | 1052篇 |
国内免费 | 5528篇 |
专业分类
安全科学 | 1365篇 |
废物处理 | 1092篇 |
环保管理 | 1606篇 |
综合类 | 9465篇 |
基础理论 | 2816篇 |
污染及防治 | 5017篇 |
评价与监测 | 784篇 |
社会与环境 | 616篇 |
灾害及防治 | 750篇 |
出版年
2024年 | 29篇 |
2023年 | 249篇 |
2022年 | 794篇 |
2021年 | 729篇 |
2020年 | 587篇 |
2019年 | 537篇 |
2018年 | 697篇 |
2017年 | 762篇 |
2016年 | 761篇 |
2015年 | 950篇 |
2014年 | 1355篇 |
2013年 | 1861篇 |
2012年 | 1418篇 |
2011年 | 1485篇 |
2010年 | 1235篇 |
2009年 | 1186篇 |
2008年 | 1277篇 |
2007年 | 1073篇 |
2006年 | 1045篇 |
2005年 | 684篇 |
2004年 | 506篇 |
2003年 | 577篇 |
2002年 | 541篇 |
2001年 | 391篇 |
2000年 | 468篇 |
1999年 | 400篇 |
1998年 | 312篇 |
1997年 | 334篇 |
1996年 | 290篇 |
1995年 | 224篇 |
1994年 | 180篇 |
1993年 | 145篇 |
1992年 | 131篇 |
1991年 | 77篇 |
1990年 | 71篇 |
1989年 | 27篇 |
1988年 | 30篇 |
1987年 | 23篇 |
1986年 | 17篇 |
1985年 | 9篇 |
1984年 | 7篇 |
1983年 | 10篇 |
1982年 | 14篇 |
1981年 | 8篇 |
1979年 | 1篇 |
1976年 | 1篇 |
1970年 | 1篇 |
1966年 | 1篇 |
1958年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
11.
Fishing‐gear restrictions and biomass gains for coral reef fishes in marine protected areas 下载免费PDF全文
Stuart J. Campbell Graham J. Edgar Rick D. Stuart‐Smith German Soler Amanda E. Bates 《Conservation biology》2018,32(2):401-410
Considerable empirical evidence supports recovery of reef fish populations with fishery closures. In countries where full exclusion of people from fishing may be perceived as inequitable, fishing‐gear restrictions on nonselective and destructive gears may offer socially relevant management alternatives to build recovery of fish biomass. Even so, few researchers have statistically compared the responses of tropical reef fisheries to alternative management strategies. We tested for the effects of fishery closures and fishing gear restrictions on tropical reef fish biomass at the community and family level. We conducted 1,396 underwater surveys at 617 unique sites across a spatial hierarchy within 22 global marine ecoregions that represented 5 realms. We compared total biomass across local fish assemblages and among 20 families of reef fishes inside marine protected areas (MPAs) with different fishing restrictions: no‐take, hook‐and‐line fishing only, several fishing gears allowed, and sites open to all fishing gears. We included a further category representing remote sites, where fishing pressure is low. As expected, full fishery closures, (i.e., no‐take zones) most benefited community‐ and family‐level fish biomass in comparison with restrictions on fishing gears and openly fished sites. Although biomass responses to fishery closures were highly variable across families, some fishery targets (e.g., Carcharhinidae and Lutjanidae) responded positively to multiple restrictions on fishing gears (i.e., where gears other than hook and line were not permitted). Remoteness also positively affected the response of community‐level fish biomass and many fish families. Our findings provide strong support for the role of fishing restrictions in building recovery of fish biomass and indicate important interactions among fishing‐gear types that affect biomass of a diverse set of reef fish families. 相似文献
12.
Tang Zhi Li Yilian Yang Zhe Liu Danqing Tang Min Yang Sen Tang Ye 《Environmental science and pollution research international》2019,26(20):20277-20285
Environmental Science and Pollution Research - The sorption/desorption behaviors of benzene, toluene, ethylbenzene, and xylene (BTEX) on soil organic matter (SOM) have a significant influence on... 相似文献
13.
Pham Thanh-Luu Tran Thi Hoang Yen Shimizu Kazuya Li Qintong Utsumi Motoo 《Environmental science and pollution research international》2021,28(45):63544-63557
Environmental Science and Pollution Research - Toxic cyanobacterial blooms (TCBs) have become a growing concern worldwide. The present study investigated the dynamic of toxic cyanobacteria and... 相似文献
14.
15.
16.
A fragment constant QSAR model for evaluating the EC50 values of organic chemicals to Daphnia magna.
Shu Tao Xiaohuan Xi Fuliu Xu Bengang Li Jun Cao R Dawson 《Environmental pollution (Barking, Essex : 1987)》2002,116(1):57-64
The quantitative relationship between the median effective concentration (EC50) of organic chemicals to Daphnia magna and the number of molecular fragments was investigated based on experimental EC50 values for 217 chemicals derived from the literature. A fragment constant model was developed based on a multivariate linear regression between the number of fragments and the logarithmically transformed reciprocal values of EC50. Functional correction factors were introduced into the model. The model was verified using an independent set of randomly selected data. The mean residual of the final model was 0.4 log-units. The robustness of the model was discussed based on the results of three jackknife tests. 相似文献
17.
三峡库区水土流失特点及其环境危害防治措施探讨 总被引:15,自引:0,他引:15
水土流失是三峡库区主要环境问题之一,也是库区产生大量泥沙的根本因素,更是造成库区人民生活贫困的根源。本文就三峡库区水土流失的特点及其环境危害作了分析,提出了相应的防治措施,为水土流失防治工程提供科学依据。 相似文献
18.
Kennedy N. Igbokwe 《中国人口.资源与环境(英文版)》2005,(1)
1 INTRODUCTIONIn the past, natural resources management initiatives havefocused on large but specific sector projects such as dams,reservoirs for water supply schemes, irrigation systems,crop production, at forestation, etc. Often these projectswere treated as technical and administrative issues ratherthan as a socio-economic and political one. However, thehigh social and environmental cost of such schemes haveled to a change of paradigm since the 1980s towards small-scale community projec… 相似文献
19.
可张孔曝气器曝气能耗试验研究 总被引:1,自引:0,他引:1
通过试验研究,总结出可张孔曝气阻力损失的影响因素,以优化产品的结构设计参数,降低产品在工程应用中的能耗,获取更好的经济效益。 相似文献
20.
A new, simple method for directly measuring activated sludge density was developed and applied, and the effects of biomass density on activated sludge settling in full-scale systems were evaluated. The driving force of sedimentation is the physical weight of the biological solids, but the role of biomass density in sedimentation has been largely ignored. Biomass density varied amongst treatment systems and this variability was correlated with settleability. Floc densities were approximately normally distributed within individual samples. Nonsoluble phosphorus content was a major contributor to density, and plants with enhanced biological phosphorus removal (EBPR) configurations generally had higher densities and better settleability than non-EBPR plants with similar filament contents. These results suggest that future work may benefit from consideration of density as a factor affecting activated sludge settling. 相似文献