全文获取类型
收费全文 | 2138篇 |
免费 | 62篇 |
国内免费 | 24篇 |
专业分类
安全科学 | 137篇 |
废物处理 | 95篇 |
环保管理 | 492篇 |
综合类 | 227篇 |
基础理论 | 563篇 |
环境理论 | 3篇 |
污染及防治 | 453篇 |
评价与监测 | 134篇 |
社会与环境 | 86篇 |
灾害及防治 | 34篇 |
出版年
2023年 | 18篇 |
2022年 | 27篇 |
2021年 | 26篇 |
2020年 | 28篇 |
2019年 | 26篇 |
2018年 | 55篇 |
2017年 | 71篇 |
2016年 | 75篇 |
2015年 | 75篇 |
2014年 | 66篇 |
2013年 | 166篇 |
2012年 | 96篇 |
2011年 | 172篇 |
2010年 | 111篇 |
2009年 | 94篇 |
2008年 | 127篇 |
2007年 | 136篇 |
2006年 | 133篇 |
2005年 | 78篇 |
2004年 | 76篇 |
2003年 | 76篇 |
2002年 | 63篇 |
2001年 | 45篇 |
2000年 | 31篇 |
1999年 | 34篇 |
1998年 | 28篇 |
1997年 | 22篇 |
1996年 | 30篇 |
1995年 | 20篇 |
1994年 | 21篇 |
1993年 | 17篇 |
1992年 | 17篇 |
1991年 | 12篇 |
1990年 | 15篇 |
1989年 | 6篇 |
1988年 | 10篇 |
1987年 | 18篇 |
1986年 | 13篇 |
1985年 | 7篇 |
1984年 | 10篇 |
1983年 | 8篇 |
1982年 | 13篇 |
1981年 | 5篇 |
1980年 | 6篇 |
1979年 | 6篇 |
1969年 | 3篇 |
1966年 | 3篇 |
1936年 | 2篇 |
1935年 | 3篇 |
1926年 | 2篇 |
排序方式: 共有2224条查询结果,搜索用时 0 毫秒
1.
2.
3.
Caching or storing surplus prey may reduce the risk of starvation during periods of food deprivation. While this behaviour occurs in a variety of birds and mammals, it is infrequent among invertebrates. However, golden orb-web spiders, Nephila edulis, incorporate a prey cache in their relatively permanent web, which they feed on during periods of food shortage. Heavier spiders significantly reduced weight loss if they were able to access a cache, but lost weight if the cache was removed. The presence or absence of stored prey had no effect on the weight loss of lighter spiders. Furthermore, N. edulis always attacked new prey, irrespective of the number of unprocessed prey in the web. In contrast, females of Argiope keyserlingi, who build a new web every day and do not cache prey, attacked fewer new prey items if some had already been caught. Thus, a necessary preadaptation to the evolution of prey caching in orb-web spiders may be a durable or permanent web, such as that constructed by Nephila. 相似文献
4.
Previous research indicates that the use of impression management is related to supervisor ratings of employee likeability and job performance. It has been argued, though, that employees might also use impression management so that their superiors will see them as ‘good soldiers’ who engage in high levels of organizational citizenship behaviors (OCBs). This study investigates the ways in which three types of impression management—namely, job‐focused, self‐focused, and supervisor‐focused tactics of impression management—influence supervisor ratings of OCB. Using a sample of 122 supervisor‐subordinate dyads, the findings indicate that supervisor‐focused tactics of impression management are positively related to OCB ratings, while job‐focused tactics are negatively related to such evaluations. Additionally, citizenship behaviors are positively related to supervisor liking of the employee and overall ratings of job performance. Finally, the results suggest that OCB ratings mediate the relationship between supervisor‐focused tactics of impression management and supervisor evaluations of employee likeability. Some implications of this study and directions for future research are also addressed. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
5.
Jerry R. Miller Mark Lord Steven Yurkovich Gail Mackin Lawrence Kolenbrander 《Journal of the American Water Resources Association》2005,41(5):1053-1075
Sedimentation rates and sediment provenance were examined for lacustrine sediments deposited in Fairfield Lake, western North Carolina, during the past 111 years. Stratigraphic, radionuclide, and cartographic data indicate that sedimentation rates have increased several fold during the past three decades in response to localized development. The magnitude of increased sedimentation was surprising given limited development within the basin: 0.12 to 0.68 buildings/ha in 2000 in those parts directly delivering sediment to the dated cores. Thus, the analysis illustrates the potential sensitivity of watersheds in the southern Appalachians to changes in land cover. An approach that combined geochemical fingerprinting with sediment mixing models was subsequently evaluated to determine its ability to accurately estimate the contribution of sediment from (1) major bedrock formations that underlie the watershed and (2) potential sources associated with four land cover categories. Sediment sources in both analyses proved difficult to geochemically fingerprint to greater than 90 percent accuracy using data on acid‐soluble metals and selected isotopes of lead (Pb). The relative contributions of sediment from delineated sources, estimated by the mixing models, generally corresponded with known temporal and spatial patterns of land cover. However, the models were plagued by two significant problems — the chemical alteration of sediments as they were transported through upland streams to depositional sites within the lake and the loss of elemental mass. Thus, future investigations using the fingerprinting approach in this area of intense weathering, and presumably others, will need to modify the existing methods to more accurately elucidate changes in sediment provenance related to development. 相似文献
6.
Indicators of ecosystem recovery 总被引:6,自引:0,他引:6
7.
8.
9.
10.