首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   31078篇
  免费   361篇
  国内免费   247篇
安全科学   913篇
废物处理   1152篇
环保管理   4210篇
综合类   4958篇
基础理论   8818篇
环境理论   22篇
污染及防治   8153篇
评价与监测   1908篇
社会与环境   1334篇
灾害及防治   218篇
  2022年   204篇
  2021年   215篇
  2020年   175篇
  2019年   237篇
  2018年   434篇
  2017年   438篇
  2016年   610篇
  2015年   529篇
  2014年   745篇
  2013年   2264篇
  2012年   906篇
  2011年   1358篇
  2010年   1098篇
  2009年   1118篇
  2008年   1341篇
  2007年   1425篇
  2006年   1263篇
  2005年   1078篇
  2004年   1074篇
  2003年   1009篇
  2002年   993篇
  2001年   1289篇
  2000年   891篇
  1999年   575篇
  1998年   445篇
  1997年   448篇
  1996年   452篇
  1995年   493篇
  1994年   448篇
  1993年   410篇
  1992年   426篇
  1991年   377篇
  1990年   382篇
  1989年   420篇
  1988年   353篇
  1987年   303篇
  1986年   281篇
  1985年   312篇
  1984年   289篇
  1983年   326篇
  1982年   327篇
  1981年   275篇
  1980年   246篇
  1979年   270篇
  1978年   230篇
  1977年   196篇
  1976年   200篇
  1975年   192篇
  1974年   174篇
  1972年   199篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
Environmental Science and Pollution Research - Legacy (i.e., polybrominated diphenyl ethers (PBDEs) and hexabromocyclododecane (HBCDD)) and alternative halogenated flame retardants (HFRs) were...  相似文献   
2.
3.
Objectives: The accuracy of self-reported driving exposure has questioned the validity of using self-reported mileage to inform research questions. Studies examining the accuracy of self-reported driving exposure compared to objective measures find low validity, with drivers overestimating and underestimating driving distance. The aims of the current study were to (1) examine the discrepancy between self-reported annual mileage and driving exposure the following year and (2) investigate whether these differences depended on age and annual mileage.

Methods: Two estimates of drivers’ self-reported annual mileage collected during vehicle installation (obtained via prestudy questionnaires) and approximated annual mileage driven (based upon Global Positioning System data) were acquired from 3,323 participants who participated in the Strategic Highway Research Program 2 (SHRP2) Naturalistic Driving Study.

Results: A Wilcoxon signed rank test showed that there was a significant difference between self-reported and annual driving exposure during participation in SHRP 2, with the majority of self-reported responses overestimating annual mileage the following year, irrespective of whether an ordinal or ratio variable was examined. Over 15% of participants provided self-reported responses with over 100% deviation, which were exclusive to participants underestimating annual mileage. Further, deviations in reporting differed between participants who had low, medium, and high exposure, as well as between participants in different age groups.

Conclusions: These findings indicate that although self-reported annual mileage is heavily relied on for research, such estimates of driving distance may be an overestimate of current or future mileage and can influence the validity of prior research that has utilized estimates of driving exposure.  相似文献   

4.
5.
Journal of Material Cycles and Waste Management - The traditional Chinese medicinal plant Magnolia officinalis has a wide range of applications; including more than 200 kinds of patented Chinese...  相似文献   
6.
Introduced and cryptogenic species in Port Phillip Bay, Victoria, Australia   总被引:4,自引:0,他引:4  
Port Phillip Bay (PPB) is a large (1,930 km2), temperate embayment in southern Victoria, Australia. Extensive bay-wide surveys of PPB have occurred since 1840. In 1995/1996 the Commonwealth Scientific and Industrial Research Organization (CSIRO) Centre for Research on Introduced Marine Pests (CRIMP) undertook an intensive evaluation of the region with the aims of developing a comprehensive species list of native and introduced biota and contrasting previous bay-wide assessments with a current field survey in order to detect new incursions and discern alterations to native communities. Two methods were used to meet these aims: a re-evaluation of regional museum collections and published research in PPB to identify and determine the timing of introductions; and field surveys for benthic (infauna, epifauna and encrusting) organisms between September 1995 to March 1996. One hundred and sixty introduced (99) and cryptogenic (61) species were identified representing over 13% of the recorded species of PPB. As expected, the majority of these are concentrated around the shipping ports of Geelong and Melbourne. Invasions within PPB appear to be increasing, possibly due to an increase in modern shipping traffic and an increase in aquaculture (historically associated with incidental introductions); however the records of extensive biological surveys suggest that this may, in part, be an artefact of sampling effort. In contrast to Northern Hemisphere studies, PPB (and Southern Hemisphere introductions in general) have significantly different suites of successfully invading taxa. PPB is presented as one of the most invaded marine ecosystems in the Southern Hemisphere.Communicated by M.S. Johnson, Crawley  相似文献   
7.
8.
9.
10.
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号