全文获取类型
收费全文 | 3776篇 |
免费 | 85篇 |
国内免费 | 37篇 |
专业分类
安全科学 | 183篇 |
废物处理 | 138篇 |
环保管理 | 942篇 |
综合类 | 364篇 |
基础理论 | 945篇 |
环境理论 | 3篇 |
污染及防治 | 914篇 |
评价与监测 | 237篇 |
社会与环境 | 148篇 |
灾害及防治 | 24篇 |
出版年
2023年 | 43篇 |
2022年 | 53篇 |
2021年 | 42篇 |
2020年 | 44篇 |
2019年 | 65篇 |
2018年 | 77篇 |
2017年 | 87篇 |
2016年 | 132篇 |
2015年 | 83篇 |
2014年 | 107篇 |
2013年 | 376篇 |
2012年 | 139篇 |
2011年 | 238篇 |
2010年 | 173篇 |
2009年 | 175篇 |
2008年 | 185篇 |
2007年 | 201篇 |
2006年 | 183篇 |
2005年 | 109篇 |
2004年 | 138篇 |
2003年 | 135篇 |
2002年 | 122篇 |
2001年 | 75篇 |
2000年 | 48篇 |
1999年 | 47篇 |
1998年 | 50篇 |
1997年 | 52篇 |
1996年 | 59篇 |
1995年 | 58篇 |
1994年 | 48篇 |
1993年 | 45篇 |
1992年 | 29篇 |
1991年 | 31篇 |
1990年 | 40篇 |
1989年 | 25篇 |
1988年 | 38篇 |
1987年 | 28篇 |
1986年 | 41篇 |
1985年 | 23篇 |
1984年 | 38篇 |
1983年 | 32篇 |
1982年 | 34篇 |
1981年 | 32篇 |
1980年 | 21篇 |
1979年 | 20篇 |
1978年 | 12篇 |
1977年 | 10篇 |
1976年 | 10篇 |
1974年 | 8篇 |
1972年 | 9篇 |
排序方式: 共有3898条查询结果,搜索用时 406 毫秒
881.
W.Kip Viscusi James T. Hamilton P.Christen Dockins 《Journal of Environmental Economics and Management》1997,34(3):187-206
This paper explores how a shift to more central estimates of risk would affect EPA decisions to remediate hazardous waste sites in the Superfund program. Analysis of 141 sites indicates that the EPA's use of conservative parameter values results in risk estimates that are 27 times greater than those based on mean values. Over 40% of sites requiring remediation would shift into the discretionary cleanup range if mean parameters were used. Though this paper examines the effect of using mean parameters for contaminant concentrations, exposure duration, and ingestion rates, additional adjustments for other conservative parameters might increase this effect. 相似文献
882.
883.
Eric Lichtfouse Valérie Sappin-Didier Laurence Denaix Giovanni Caria Laure Metzger Najat Amellal-Nassr Jens Schmidt 《Environmental Chemistry Letters》2005,3(3):140-144
We studied polycyclic aromatic hydrocarbons (PAHs) in crop soils amended with 1000 tonnes dry weight of sewage sludges per
10,000 m2 from 1974 to 1992, then after sludges addition from 1993 to 1999. The absence of variations of total PAHs levels of control
soils, averaging at 123 μg/Kg, shows the absence of horizontal contamination. During sludges addition, the total PAHs levels
in amended soils increased from 232 to 402 μg/Kg. Seven years after sludges addition, it decreased to 275 μg/Kg, which is
still more than twice –the levels of control soils. This finding shows that sludges PAHs are preserved in crop soils for long
periods of time, on a human scale. 相似文献
884.
885.
James?C.?NiehEmail author Felipe?A.?L.?Contrera Juliana?Rangel Vera?L.?Imperatriz-Fonseca 《Behavioral ecology and sociobiology》2003,55(1):87-94
It is unclear whether stingless bees in the genus Melipona (Hymenoptera, Apidae, Meliponini) can reliably encode the distance to a food source through recruitment sounds produced inside the nest, in part because the sound features correlated with distance also vary with food quality. We therefore trained marked foragers of two species, Melipona mandacaia and M. bicolor, to feeders at different distances and to different sucrose concentrations at the same distance. In both species, foragers successfully recruited to a rich 2.5-m food source and produced pulsed recruitment sounds in which pulse duration was significantly and positively correlated with distance to the rich food source. When returning from poorer food sources (0.6–1.5 m), foragers of both species decreased sound production, producing shorter sound pulses and longer sound interpulses than they did for 2.5 m food located at the same distance. Thus the temporal structure of M. mandacaia and M. bicolor recruitment sounds varies with distance and food quality. However, nestmates were not recruited by performances for poorer food sources (0.6–1.5 m), whose sucrose concentration was sufficiently low to affect recruitment sounds. Surprisingly, the interphase (the time between behavioral phases that communicate location) also increases with decreasing food quality in the closely related honeybees (Apis), suggesting a potential homology in the effect of food quality on the recruitment systems of Apis and Melipona. We explore the evolutionary implications of these similarities.Communicated by M. Giurfa 相似文献
886.
887.
James V. Zidek Gavin Shaddick Jean Meloche Chris Chatfield Rick White 《Environmental and Ecological Statistics》2007,14(4):411-431
This paper presents a general framework for constructing a predictive distribution of the exposure to an environmental hazard
sustained by a randomly selected member of a designated population. The individual’s exposure is assumed to arise from random
movement through the environment, resulting in a distribution of exposure that can be used for environmental risk analysis.
A specialization of the general framework is that of predicting human exposure to air pollution that can be used to develop
models for such things as exposure to particulate matter; practical aspects of their construction are considered. These models
can help answer questions such as what fraction of the population sustained ‘high’ levels of exposure for say 5 days in a
row. The immediate implementation of the above framework takes the form of a computing platform referred to as pCNEM. This provides a facility for simulating exposures to airborne pollutants and is described in detail elsewhere. This paper
considers some theoretical aspects underpinning probabilistic exposure models of this type, with the ideas illustrated in
developing a model for predicting human exposure to PM
10. 相似文献
888.
On 9 October, 1985 a daytime surface swarm of the euphausiid Euphausia lucens was observed and sampled in St. Helena Bay in the Southern Benguela region. The swarm was monospecific, consisted of adults in prebreeding condition and appeared to be feeding on detrital material. The swarm covered an estimated 46 ha, densities within it ranged between 4 000 and 1 500 000 individuals per cubic metre and the swarm was estimated to contain 5 000 tonnes of euphausiids. No simple explanation for the presence of the swarm was apparent. 相似文献
889.
Tail size and female choice in the guppy (Poecilia reticulata) 总被引:6,自引:0,他引:6
Robert J. Bischoff James L. Gould Daniel I. Rubenstein 《Behavioral ecology and sociobiology》1985,17(3):253-255
Summary Under laboratory conditions, female guppies demonstrate a clear preference for males with larger tails, and this preference translates into enhanced reproductive fitness for these males. Females also prefer males with higher display rates, a behavior which appears to be linked to tail size, but which can be experimentally disassociated. This appears to be a case of female-choice sexual selection. 相似文献
890.
Optimal foraging: Some simple stochastic models 总被引:5,自引:0,他引:5
Summary Some simple stochastic models of optimal foraging are considered. Firstly, mathematical renewal theory is used to make a general model of the combined processes of search, encounter, capture and handling. In the case where patches or prey items are encountered according to a Poisson process the limiting probability distribution of energy gain is found. This distribution is found to be normal and its mean and variance are specified. This result supports the use of Holling's disc equation to specify the rate of energy intake in foraging models. Secondly, a model based on minimization of the probability of death due to an energetic shortfall is presented. The model gives a graphical solution to the problem of optimal choices when mean and variance are related. Thirdly, a worked example using these results is presented. This example suggests that there may be natural relationships between mean and variance which make solutions to the problems of energy maximization and minimization of the probability of starvation similar. Finally, current trends in stochastic modeling of foraging behavior are critically discussed. 相似文献