全文获取类型
收费全文 | 415篇 |
免费 | 9篇 |
国内免费 | 8篇 |
专业分类
安全科学 | 42篇 |
废物处理 | 15篇 |
环保管理 | 93篇 |
综合类 | 53篇 |
基础理论 | 85篇 |
环境理论 | 1篇 |
污染及防治 | 100篇 |
评价与监测 | 28篇 |
社会与环境 | 9篇 |
灾害及防治 | 6篇 |
出版年
2023年 | 4篇 |
2022年 | 3篇 |
2021年 | 2篇 |
2020年 | 3篇 |
2019年 | 10篇 |
2018年 | 11篇 |
2017年 | 10篇 |
2016年 | 11篇 |
2015年 | 16篇 |
2014年 | 10篇 |
2013年 | 36篇 |
2012年 | 12篇 |
2011年 | 33篇 |
2010年 | 21篇 |
2009年 | 22篇 |
2008年 | 25篇 |
2007年 | 17篇 |
2006年 | 29篇 |
2005年 | 20篇 |
2004年 | 11篇 |
2003年 | 12篇 |
2002年 | 12篇 |
2001年 | 8篇 |
2000年 | 8篇 |
1999年 | 4篇 |
1998年 | 4篇 |
1997年 | 4篇 |
1996年 | 6篇 |
1995年 | 5篇 |
1994年 | 5篇 |
1993年 | 6篇 |
1992年 | 8篇 |
1991年 | 2篇 |
1990年 | 8篇 |
1989年 | 6篇 |
1988年 | 5篇 |
1987年 | 3篇 |
1986年 | 2篇 |
1985年 | 2篇 |
1984年 | 6篇 |
1983年 | 1篇 |
1982年 | 3篇 |
1981年 | 1篇 |
1980年 | 1篇 |
1979年 | 1篇 |
1978年 | 1篇 |
1976年 | 1篇 |
1971年 | 1篇 |
排序方式: 共有432条查询结果,搜索用时 15 毫秒
31.
32.
Lesiv Myroslava Shvidenko Anatoly Schepaschenko Dmitry See Linda Fritz Steffen 《Mitigation and Adaptation Strategies for Global Change》2019,24(6):985-1006
Mitigation and Adaptation Strategies for Global Change - The spatial representation of forest cover and forest parameters is a prerequisite for undertaking a systems approach to the full and... 相似文献
33.
34.
Numerous cases of hereditary diseases and disorders have been reported in wild animals bred in captivity, but little attention has been paid to the particular genetic management problems that arise when such defects occur. These problems include the obstacle of eliminating the deleterious allele(s) without contemporary loss of genetic variability. In this paper we use the statistical methods of pedigree analysis to address questions regarding a previously presumed hereditary form of blindness observed in a captive wolf population bred for conservation purposes in Scandinavian zoos. The most likely mode of inheritance coincides with an autosomal recessive allele with either a full penetrance or a reduced penetrance of 0.6 (depending on the reliability of studbook records). Using these two models of inheritance, we calculate the probability of carrying the blindness allele for each living animal. Analysis of the effect of removing high-probability carriers on founder allele survival and level of inbreeding demonstrates that the frequency of the deleterious allele can be significantly reduced without seriously affecting founder allele survival or current degree of inbreeding in the wolf population. 相似文献
35.
Linda Groat 《Journal of environmental psychology》1982,2(1):3-22
The relevance of the multiple sorting task as a research tactic for the empirical study of environmental meaning is illustrated in the context of a specific study of Modern and Post-Modern architecture. The assumption of architectural critics that Post-Modern buildings are more meaningful to the general public than Modern buildings forms the basis for the research hypotheses of this study. Twenty-four buildings, ranging from Modern to Post-Modern are evaluated by 20 architects and 20 accountants whose responses are structured through a multiple sorting task. The sorting data are interpreted in terms of regional analyses of multi-dimensional scaling structures, following the general principles of Facet Theory. These results suggest that (1) architects and accountants do employ different sets of criteria (different codes, in effect) for evaluating buildings, and yet (2) Post-Modern buildings (despite their architects' intentions of relating their designs to a popular code) are not perceived by the accountants as distinct from Modern buildings. The particular strengths of the multiple sorting task as a research tactic for this and other studies of environmental meaning are discussed and summarized. 相似文献
36.
Keeling LJ 《Ambio》2005,34(4-5):316-319
Good animal welfare is necessary if an agricultural system is to be sustainable. Although we have been concerned about the welfare of our animals since we first domesticated them and became dependent on their health and reproduction, this article focuses mainly on the development of the animal welfare debate since the 1960s. It presents animal welfare as a science that arose from society's concern about the way animals are kept. These moral and ethical concerns lead to it having a value framework that must also be taken into consideration. Different definitions of animal welfare, as well as examples of research, are presented and discussed in the light of developments in this area. For example, in recent years there has been an increased interest among consumers for animal-friendly products, as there has been for environment friendly products, and this has stimulated the move from experimental studies of animal welfare to its application in practice and to monitoring animal welfare on farms. Traditionally such measurements have been resource based, e.g. specifying the minimum amount of feeding space or the maximum stocking density, but now the trend is toward animal-based measures, such as the numberof lame animals, body condition, etc. 相似文献
37.
Studies of carbon fluxes in marine ecosystems are often done by using box model approaches with basin size boxes, or highly resolved 3D models, and an emphasis on the pelagic component of the ecosystem. Those approaches work well in the ocean proper, but can give rise to considerable problems when applied to coastal systems, because of the scale of certain ecological niches and the fact that benthic organisms are the dominant functional group of the ecosystem. In addition, 3D models require an extensive modeling effort. In this project, an intermediate approach based on a high resolution (20x20 m) GIS data-grid has been developed for the coastal ecosystem in the Laxemar area (Baltic Sea, Sweden) based on a number of different site investigations. The model has been developed in the context of a safety assessment project for a proposed nuclear waste repository, in which the fate of hypothetically released radionuclides from the planned repository is estimated. The assessment project requires not only a good understanding of the ecosystem dynamics at the site, but also quantification of stocks and flows of matter in the system. The data-grid was then used to set up a carbon budget describing the spatial distribution of biomass, primary production, net ecosystem production and thus where carbon sinks and sources are located in the area. From these results, it was clear that there was a large variation in ecosystem characteristics within the basins and, on a larger scale, that the inner areas are net producing and the outer areas net respiring, even in shallow phytobenthic communities. Benthic processes had a similar or larger influence on carbon fluxes as advective processes in inner areas, whereas the opposite appears to be true in the outer basins. As many radionuclides are expected to follow the pathways of organic matter in the environment, these findings enhance our abilities to realistically describe and predict their fate in the ecosystem. 相似文献
38.
39.
Filial cannibalism in burying beetles 总被引:4,自引:0,他引:4
J. Bartlett 《Behavioral ecology and sociobiology》1987,21(3):179-183
Summary Infanticide is a common phenomenon in many animal groups, but filial cannibalism, the deliberate killing and consumption by parents of their own young, is extremely unusual. The burying beetle Nicrophorus vespilloides Herbst has a limited food supply, in the form of a buried corpse, on which to raise its young. On corpses weighing 10–15 g, clutch size in the lab is such that complete hatching can support without severe reduction in the individual weights of final instars. The parents reduce the brood by killing and eating almost half of the first stage larvae. It is suggested that, in the field, predation of eggs and newly hatched larvae may be heavy, and that the excess eggs are laid as an insurance. If survival is then unusually high, superfluous young are killed by the parents before competition for food can occur. 相似文献
40.
Most resource allocation models developed to aid resource planning have been deterministic; that is, the ecosystem and economic variables are assumed to be known with certainty. It is these elements that present problems concerning risk and uncertainty involved in decision making. The objective of this study is to present a mathematical approach for optimizing resource allocation in management situations in which random events occur. This particular technique of decision analysis is chance-constrained programming. The model makes possible the investigation of risk and uncertainty associated with resource management decision making. Range decision-makers must often stock their range before they are sure of the available forage; thus, the amount of available forage is a random element with which managers must contend. The chance-constrained approach to decision making may be used when such random events occur and when it is not possible to plan exactly for future events. Two parameters are used to adjust the mean value of constraints; these are the standard deviation of the constraint value (Sbi) and the probability term which is specified by the manager (Kαi). The mean values are adjusted by the product KαiSbi. In the study reported here, a Kαi value of 0.57 gave results which appeared to have usefulness. The results indicate that the penalties a rancher must assume for over-estimating his carrying capacity are greater than the penalties for underestimating the carrying capacity. With the value of the standard deviation used in the example, numbers of livestock and the corresponding net revenues should be about 22% less than those indicated by average forage production. With greater variation in forage production, the reduction would be greater. By using these values, the chance-constrained approach can meaningfully incorporate random variables into a decision model. 相似文献