全文获取类型
收费全文 | 1238篇 |
免费 | 49篇 |
国内免费 | 95篇 |
专业分类
安全科学 | 50篇 |
废物处理 | 44篇 |
环保管理 | 198篇 |
综合类 | 292篇 |
基础理论 | 316篇 |
环境理论 | 1篇 |
污染及防治 | 327篇 |
评价与监测 | 87篇 |
社会与环境 | 57篇 |
灾害及防治 | 10篇 |
出版年
2024年 | 2篇 |
2023年 | 44篇 |
2022年 | 47篇 |
2021年 | 34篇 |
2020年 | 26篇 |
2019年 | 41篇 |
2018年 | 37篇 |
2017年 | 50篇 |
2016年 | 56篇 |
2015年 | 49篇 |
2014年 | 61篇 |
2013年 | 113篇 |
2012年 | 57篇 |
2011年 | 102篇 |
2010年 | 74篇 |
2009年 | 48篇 |
2008年 | 62篇 |
2007年 | 68篇 |
2006年 | 75篇 |
2005年 | 38篇 |
2004年 | 34篇 |
2003年 | 39篇 |
2002年 | 37篇 |
2001年 | 34篇 |
2000年 | 13篇 |
1999年 | 8篇 |
1998年 | 12篇 |
1997年 | 15篇 |
1996年 | 17篇 |
1995年 | 8篇 |
1994年 | 11篇 |
1993年 | 8篇 |
1992年 | 6篇 |
1991年 | 3篇 |
1990年 | 6篇 |
1989年 | 2篇 |
1988年 | 8篇 |
1987年 | 4篇 |
1986年 | 4篇 |
1985年 | 2篇 |
1984年 | 3篇 |
1983年 | 6篇 |
1982年 | 4篇 |
1981年 | 3篇 |
1980年 | 4篇 |
1979年 | 3篇 |
1976年 | 1篇 |
1965年 | 1篇 |
1941年 | 1篇 |
1936年 | 1篇 |
排序方式: 共有1382条查询结果,搜索用时 531 毫秒
981.
Eric Jauniaux Catherine Donner Christine Thomas Jacques Francotte Frédéric Rodesch Freddy E. Avni 《黑龙江环境通报》1988,8(8):557-563
Prenatal diagnosis of cord defects by means of ultrasound examination is possible and highly accurate. Although this is a rare pathological finding, we report two cases in which umbilical cord pseudocysts were associated with trisomy 18. These observations underscore the need of umbilical blood sampling for establishing the karyotype in fetuses with such umbilical cord anomalies and the importance of careful examination of placentas and infants born with such defects. 相似文献
982.
Dyke GJ Dortangs RW Jagt JW Mulder EW Schulp AS Chiappe LM 《Die Naturwissenschaften》2002,89(9):408-411
Birds known from more than isolated skeletal elements are rare in the fossil record, especially from the European Mesozoic. This paucity has hindered interpretations of avian evolution immediately prior to, and in the aftermath of, the Cretaceous-Tertiary (K-T) extinction event. We report on a specimen of a large ornithurine bird (closely related to Ichthyornis) from the uppermost Cretaceous (Maastricht Formation) of Belgium. This is the first record of a bird from these historic strata and the only phylogenetically informative ornithurine to be recovered from the Mesozoic of Europe. Because this new specimen was collected from 40 m below the K-T boundary (approximate age of 65.8 Ma), it is also the youngest non-neornithine (=non-modern) bird known from anywhere in the world. 相似文献
983.
Theoretical signaling models predict that to be honest, begging vocalizations must be costly. To test this hypothesis, oxygen consumption was measured during resting and begging (i.e., vocalizing) activities in pups of the subterranean rodent Ctenomys talarum by means of open-flow respirometry. No statistical differences in individual oxygen consumption between resting and calling pups ranging in age from day 2 to day 20 were found. Given these data, begging calls of C. talarum could not be considered as honest advertisements of offspring need, contrary to what suggested by the behavioral observations of the mother and pups during the nestling period. 相似文献
984.
985.
986.
Mussel culture in coastal environments relies on the availability of food of sufficient quality and quantity. Both to determine
this availability and to examine impacts that this aquaculture practice may have on the environment, it is important to have
good knowledge of the type of plankton communities present in aquaculture sites. It is usually thought that phytoplankton
make up the bulk of mussel diet in many of these sites. Here we show that the Grande-Entrée lagoon [Magdalen Islands, Gulf
of St Lawrence (GSL), Canada], where commercial mussel culture has been on-going since 1980, differs from this pattern. Heterotrophic
protists dominate for most of the summer-early fall season (apart from short diatom bursts), with a high average biomass of
160 mg C m−3. The dominance of small-sized phytoplankton cells (notably green algae), low nutrient concentrations (e.g. 0.3 μM NO3− on average) and high biomass of heterotrophic protists (mostly naked ciliates and tintinnids) all point to the importance
of the microbial food web in this shallow marine environment. Sustained cultivation of suspended mussels in the lagoon suggests
that these heterotrophic protists could be an important source of food for the mussels, supplementing the small amount of
phytoplankton present. 相似文献
987.
Eric W Seabloom 《Ecological applications》2007,17(7):1876-1885
The relationship between community diversity and the stability of summed community biomass has been an area of great theoretical and empirical interest in basic ecology. In general, it has been found that the complementary/compensatory dynamics among species that comprise a community can stabilize aggregate measures of community biomass. Although the potential importance of diversity-stability relationships to restoration ecology has been recognized, to date there has been no quantification of the role these relationships play in increasing the persistence of restored communities in the face of altered disturbance regimes, climatic variability, and over the course of succession. In a large-scale experimental restoration of a California grassland community, aggregated abundance of restored grasses was more stable than were the individual species in response to disturbance, drought, and succession. Compensatory dynamics among the restored grass flora increased aggregate stability in response to natural and anthropogenic disturbances. Successful restorations must persist in the face of altered management and disturbance regimes, climactic variability, and over the course of succession. Incorporation of diversity-stability relationships into restoration plans will likely increase restoration success. This case study further demonstrates the relevance of community ecology theory to restoration ecology. 相似文献
988.
A growing number of scientific studies in recent years have investigated disparate exposure to ecological hazards in American society. Working from an environmental justice perspective, this body of research consistently reveals that poor communities of color are most likely to bear a disproportionate burden of negative externalities. These studies utilize a wide range of research methodologies, including various indicators of ecological hazards (e.g., proximity to waste sites, industrial emissions, ambient air quality), but few, if any, utilize composite measures to approximate cumulative environmental impact. Consequently, the environmental justice (EJ) literature is characterized by a failure to effectively measure overall impact from an extensive range of ecological hazards. Limitations on available data make this a serious problem for present and future studies. We argue that cumulative measures of environmental impact can play an important role in furthering our understanding of environmental injustices in the United States. In this study of Massachusetts, we develop and implement such a cumulative measure of negative environmental impacts. By controlling for the density and severity of ecological hazardous sites and facilities within every community in the state, we demonstrate that exposure patterns take a generally linear distribution when analyzed by race and class. So, while our results reaffirm previous findings that low-income communities and communities of color bear significantly greater ecological burdens than predominantly White and more affluent communities, our findings also suggest that environmental injustices exist on a remarkably consistent continuum for nearly all communities. In other words, as the minority population and lower-income composition of a community increases, correspondingly, so does cumulative exposure to environmental hazards. In this respect, communities which are more racially mixed and of moderate income status that are not typically identified as meeting EJ criteria (in demographic terms) also face more significant ecological hazards. Thus, the strict bifurcation of communities into categories of Environmental Justice and Non-Environmental Justice is problematic, and poses a serious dilemma for policy makers, public health officials, and community activists. To overcome this challenge requires the adoption of a cumulative environmental justice impact assessment (CEJIA), which in addition to the demographic characteristics of a community, also takes into account the total environmental burden and related health impacts upon residents. Furthermore, through the adoption of the precautionary principle, source reduction, and alternative forms of “cleaner” production, environmental justice advocates must work for policies which reduce the environmental threat for the full range of communities, as well as their own. 相似文献
989.
水中硫化氢的溶解规律 总被引:2,自引:0,他引:2
对气体在水中的溶解机制进行了分析,并结合实验数据导出了硫化氢在水中溶解度的预测公式,该预测公式准确度较高,其平均绝对误差及平均相对误差分别为0.026g/L和0.062%. 相似文献
990.
Host-plant green-leaf volatiles synergize the synthetic sex pheromones of the corn earworm and codling moth (Lepidoptera) 总被引:8,自引:0,他引:8
Douglas M. Light Robert A. Flath Ronald G. Buttery Frank G. Zalom Richard E. Rice Joseph C. Dickens Eric B. Jang 《Chemoecology》1993,4(3-4):145-152
Summary The capture of adult male moths in female sex pheromone traps of two key agricultural pests, the corn earworm (Helicoverpa zea) and the codling moth (Cydia pomonella), is enhanced or synergized by a certain group of host-plant volatiles, the green-leaf volatiles (GLVs). Since female adults of both species call and release their sex pheromones while perched upon the leaves of their host-plants, the volatile constituents from the leaves of a number of host-plants were compared. Sex pheromone traps containing one of the prominent leaf volatiles of certainH. zea hosts, (Z)-3-hexenyl acetate, not only significantly increased the capture ofH. zea males but were preferred over traps baited only with sex pheromone. Similarly, traps baited with synthetic sex pheromome ofC. pomonella plus a blend of GLVs captured significantly more males than traps baited only with sex pheromone. Since male moths are not captured in traps baited only with these GLVs, it appears that these GLVs act as pheromone synergists which increase or enhance the attraction or arrestment of male moths in pheromone traps. 相似文献