全文获取类型
收费全文 | 1805篇 |
免费 | 28篇 |
国内免费 | 15篇 |
专业分类
安全科学 | 54篇 |
废物处理 | 67篇 |
环保管理 | 298篇 |
综合类 | 303篇 |
基础理论 | 431篇 |
环境理论 | 4篇 |
污染及防治 | 469篇 |
评价与监测 | 134篇 |
社会与环境 | 83篇 |
灾害及防治 | 5篇 |
出版年
2023年 | 19篇 |
2022年 | 20篇 |
2021年 | 25篇 |
2020年 | 24篇 |
2019年 | 23篇 |
2018年 | 39篇 |
2017年 | 47篇 |
2016年 | 43篇 |
2015年 | 46篇 |
2014年 | 50篇 |
2013年 | 127篇 |
2012年 | 73篇 |
2011年 | 108篇 |
2010年 | 78篇 |
2009年 | 92篇 |
2008年 | 95篇 |
2007年 | 115篇 |
2006年 | 84篇 |
2005年 | 73篇 |
2004年 | 72篇 |
2003年 | 67篇 |
2002年 | 78篇 |
2001年 | 33篇 |
2000年 | 26篇 |
1999年 | 18篇 |
1998年 | 19篇 |
1997年 | 23篇 |
1996年 | 18篇 |
1995年 | 23篇 |
1994年 | 25篇 |
1993年 | 13篇 |
1992年 | 16篇 |
1991年 | 15篇 |
1990年 | 12篇 |
1989年 | 12篇 |
1988年 | 17篇 |
1987年 | 12篇 |
1986年 | 15篇 |
1984年 | 8篇 |
1983年 | 10篇 |
1982年 | 11篇 |
1981年 | 9篇 |
1980年 | 7篇 |
1979年 | 10篇 |
1978年 | 7篇 |
1977年 | 5篇 |
1976年 | 6篇 |
1974年 | 6篇 |
1955年 | 5篇 |
1954年 | 8篇 |
排序方式: 共有1848条查询结果,搜索用时 31 毫秒
891.
Snoussi M Kitheka J Shaghude Y Kane A Arthurton R Le Tissier M Virji H 《Environmental management》2007,39(5):587-600
Anthropogenic factors associated with damming and water abstraction, and the resultant environmental pressures, are reviewed
in six African river catchments using records and forecasts of climatic, demographic, and land-use change. Changes in the
states of the flow regime through catchment drainage systems to the coastal sea are considered in conjunction with climate
change and other human-induced pressures. The impacts of these changes on downstream and coastal environments and their communities
are described in past, present, and future perspectives. Linkages between the issues and the pressures of damming and water
abstraction are appraised and scientific, policy, and management responses proposed aimed at remedying existing and perceived
future negative impacts. The study proposes that there is a need to integrate catchment and coastal management to account
for the whole water flow regime together with its human dimensions. Management priorities relating to the operation of existing
damming and abstraction schemes and planning of future schemes include the following: consideration of ways in which water
discharges could be adjusted to provide improvements in downstream and coastal environmental and socioeconomic conditions;
addressing the problem of sediment trapping impacting on the sustainability of dam reservoirs; and assessment of downstream
and coastal impacts of future schemes in the light of climate change forecasts. 相似文献
892.
This paper examines whether corporate financial performance is affected by public endorsement of environmental and social performance. Event study methodology, which relies on the notion of market efficiency, is used to examine the relationship between positive and negative announcements and changes in share prices or daily returns. Inclusion in and deletion from the FTSE4Good UK Index is used as a proxy measure for good (poor) corporate social responsibility. The abnormal or unexpected daily returns associated with an event are calculated and their significance tested. The results show a trend towards positive and negative announcements having the expected effects on daily returns. But these movements are not significant and the data do not suggest that a firm's presence on the index brings it any significant financial return for signalling its corporate social responsibility. 相似文献
893.
Evaluating Costs of Conservation 总被引:7,自引:0,他引:7
894.
895.
896.
897.
898.
899.
Pauline Coster Mouloud Benammi Vincent Lazzari Guillaume Billet Thomas Martin Mustafa Salem Awad Abolhassan Bilal Yaowalak Chaimanee Mathieu Schuster Xavier Valentin Michel Brunet Jean-Jacques Jaeger 《Die Naturwissenschaften》2010,97(8):697-706
A new African species of hystricognathous rodent, Gaudeamus lavocati sp. nov., is described herein from the early Oligocene deposits of Zallah locality (Sirt basin, Central Libya). The dental morphology of this species is very close to that of some earliest South American caviomorphs. It allows a reinterpretation of molar crest homologies among earliest caviomorphs, pentalophodonty being confirmed as the plesiomorphic molar condition in Caviomorpha. This morphological resemblance argues for close affinities between Gaudeamus and earliest South American hystricognaths. Cladistic analysis supports Gaudeamus lavocati sp. nov. as the first known African representative of Caviomorpha, implying that its ancestors were part of the African phiomyid group that crossed the South Atlantic by a direct immigration route. Alternatively, the series of derived dental features of Gaudeamus could also be interpreted as evolutionary synchronous convergences of an African hystricognath lineage towards the specialized pattern of some caviomorphs. However, the high level of similarities concerning teeth morphology and enamel microstructure and the similar age of fossiliferous strata on both continents make this interpretation less probable. The phylogenetic position of this taxon is of considerable importance because it represents an enigmatic component of the phiomorph–caviomorph radiation in Africa and appears as a new clue toward the understanding of caviomorph origins. 相似文献
900.
Konstantin Stolpovsky Paula Martinez-LavanchyHermann J. Heipieper Philippe Van Cappellen Martin Thullner 《Ecological modelling》2011,222(17):3092-3102
Biogeochemical activity in natural and engineered systems depends on the abundances, functional capabilities and physiological states of the indigenous microorganisms. Typically, only a fraction of the microbial population is active at any given time. As environmental conditions change, previously active microorganisms may switch to an inactive or dormant state, while dormant ones may become active. Here, we present an extended modeling concept for the growth and decay of microorganisms that explicitly accounts for their ability to switch between active and dormant states. The equations describing the switching between physiological states are implemented into a biogeochemical reaction simulator. The model was used to reproduce published data from two laboratory experiments in which microorganisms were subjected to intermittent substrate supply or reactivated after a prolonged period of starvation. Parameter values obtained from the simulation of these experiments were used for subsequent sensitivity analyses and for the simulation of hypothetical scenarios. Results for hypothetical microbial communities consisting of two competing species exposed to periodic feeding imply that, under certain conditions, an effective dormancy-reactivation strategy may have a competitive advantage over a fast growth strategy. That is, organisms that can switch rapidly in response to fluctuations in external conditions may outcompete fast-growing organisms. Furthermore, certain combinations of growth and dormancy strategies may lead to the long-term coexistence of the two competing species. Overall, the simulated population dynamics show that dormancy is an important feature of microbial communities, which can lead to complex responses to environmental fluctuations. 相似文献