全文获取类型
收费全文 | 6418篇 |
免费 | 98篇 |
国内免费 | 58篇 |
专业分类
安全科学 | 359篇 |
废物处理 | 264篇 |
环保管理 | 1516篇 |
综合类 | 645篇 |
基础理论 | 1563篇 |
环境理论 | 12篇 |
污染及防治 | 1507篇 |
评价与监测 | 428篇 |
社会与环境 | 233篇 |
灾害及防治 | 47篇 |
出版年
2023年 | 33篇 |
2022年 | 58篇 |
2021年 | 53篇 |
2020年 | 47篇 |
2019年 | 66篇 |
2018年 | 106篇 |
2017年 | 130篇 |
2016年 | 168篇 |
2015年 | 125篇 |
2014年 | 158篇 |
2013年 | 708篇 |
2012年 | 268篇 |
2011年 | 346篇 |
2010年 | 234篇 |
2009年 | 254篇 |
2008年 | 303篇 |
2007年 | 372篇 |
2006年 | 283篇 |
2005年 | 219篇 |
2004年 | 222篇 |
2003年 | 239篇 |
2002年 | 194篇 |
2001年 | 124篇 |
2000年 | 123篇 |
1999年 | 97篇 |
1998年 | 94篇 |
1997年 | 86篇 |
1996年 | 103篇 |
1995年 | 95篇 |
1994年 | 102篇 |
1993年 | 84篇 |
1992年 | 83篇 |
1991年 | 65篇 |
1990年 | 65篇 |
1989年 | 49篇 |
1988年 | 52篇 |
1987年 | 50篇 |
1986年 | 58篇 |
1985年 | 50篇 |
1984年 | 48篇 |
1983年 | 62篇 |
1982年 | 75篇 |
1981年 | 68篇 |
1980年 | 43篇 |
1979年 | 42篇 |
1978年 | 29篇 |
1977年 | 40篇 |
1976年 | 21篇 |
1974年 | 20篇 |
1971年 | 17篇 |
排序方式: 共有6574条查询结果,搜索用时 843 毫秒
911.
912.
913.
914.
915.
916.
917.
Paul Beier Patricia Sutcliffe Jan Hjort Daniel P. Faith Robert L. Pressey Fabio Albuquerque 《Conservation biology》2015,29(3):668-679
Because conservation planners typically lack data on where species occur, environmental surrogates—including geophysical settings and climate types—have been used to prioritize sites within a planning area. We reviewed 622 evaluations of the effectiveness of abiotic surrogates in representing species in 19 study areas. Sites selected using abiotic surrogates represented more species than an equal number of randomly selected sites in 43% of tests (55% for plants) and on average improved on random selection of sites by about 8% (21% for plants). Environmental diversity (ED) (42% median improvement on random selection) and biotically informed clusters showed promising results and merit additional testing. We suggest 4 ways to improve performance of abiotic surrogates. First, analysts should consider a broad spectrum of candidate variables to define surrogates, including rarely used variables related to geographic separation, distance from coast, hydrology, and within‐site abiotic diversity. Second, abiotic surrogates should be defined at fine thematic resolution. Third, sites (the landscape units prioritized within a planning area) should be small enough to ensure that surrogates reflect species’ environments and to produce prioritizations that match the spatial resolution of conservation decisions. Fourth, if species inventories are available for some planning units, planners should define surrogates based on the abiotic variables that most influence species turnover in the planning area. Although species inventories increase the cost of using abiotic surrogates, a modest number of inventories could provide the data needed to select variables and evaluate surrogates. Additional tests of nonclimate abiotic surrogates are needed to evaluate the utility of conserving nature's stage as a strategy for conservation planning in the face of climate change. 相似文献
918.
919.
Multisource data collected at three time phases were used in investigating when servant leadership elicits gratitude and then promotes prosocial behaviors. We tested a moderated mediation model, contending that relational attributions moderate the relationship between servant leadership and gratitude, and then gratitude sequentially predicts interpersonal citizenship behaviors and upward voice. As hypothesized, when employees do not highly rely on relational attributions for servant leadership, they feel more gratitude and subsequently engage in more interpersonal citizenship behaviors and upward voice than the employees who rely on relational attributions to explain their interactions with the leader. The sequential indirect effect from servant leadership to upward voice via gratitude and then interpersonal citizenship behaviors was significant when relational attributions are low rather than high. 相似文献
920.
Thomas W. Pike 《Behavioral ecology and sociobiology》2005,58(4):407-413
A number of recent reports have documented offspring sex ratio biases in birds. However, to date the potential mechanisms that have been put forward to explain the proximate basis for these deviations are entirely speculative. Using a captive population of domestic pigeons (Columba livia domestica), I tested the hypothesis that mothers in relatively poor physical condition should overproduce daughters by manipulating maternal body condition around the time of egg laying by continuous egg removal and differing feeding regimes. During treatment, females were fed a controlled quantity of food. This, combined with the high energetic costs of repeated egg production caused a significant reduction in maternal body weight. In contrast, during control when food was available ad libitum, maternal body weight did not decline, despite repeated egg production. No significant deviation from parity was evident in the sex ratio of either the first or second eggs during control, whereas during treatment a significant female bias was evident in not only the first egg, but also in the second egg. The absence of single-egg clutches, the rarity of infertile eggs and the lack of laying delays between eggs strongly suggests that the mechanism of sex ratio adjustment in pigeons occurs prior to ovulation. The highly skewed sex-distribution within the two-egg clutches and the unexpectedly large amount of variation in the yolk weight of eggs produced during treatment (but not control) are consistent with the expectations of pre-ovulatory selective resorption of wrong sex ovarian follicles. 相似文献