全文获取类型
收费全文 | 32451篇 |
免费 | 357篇 |
国内免费 | 290篇 |
专业分类
安全科学 | 940篇 |
废物处理 | 1256篇 |
环保管理 | 4539篇 |
综合类 | 5208篇 |
基础理论 | 8869篇 |
环境理论 | 14篇 |
污染及防治 | 8324篇 |
评价与监测 | 2007篇 |
社会与环境 | 1709篇 |
灾害及防治 | 232篇 |
出版年
2022年 | 232篇 |
2021年 | 264篇 |
2020年 | 195篇 |
2019年 | 254篇 |
2018年 | 438篇 |
2017年 | 487篇 |
2016年 | 743篇 |
2015年 | 567篇 |
2014年 | 799篇 |
2013年 | 2620篇 |
2012年 | 1076篇 |
2011年 | 1336篇 |
2010年 | 1043篇 |
2009年 | 1168篇 |
2008年 | 1335篇 |
2007年 | 1426篇 |
2006年 | 1280篇 |
2005年 | 1303篇 |
2004年 | 1391篇 |
2003年 | 1310篇 |
2002年 | 952篇 |
2001年 | 1187篇 |
2000年 | 891篇 |
1999年 | 510篇 |
1998年 | 402篇 |
1997年 | 378篇 |
1996年 | 443篇 |
1995年 | 442篇 |
1994年 | 421篇 |
1993年 | 400篇 |
1992年 | 374篇 |
1991年 | 360篇 |
1990年 | 377篇 |
1989年 | 333篇 |
1988年 | 312篇 |
1987年 | 283篇 |
1986年 | 274篇 |
1985年 | 292篇 |
1984年 | 311篇 |
1983年 | 312篇 |
1982年 | 302篇 |
1981年 | 313篇 |
1980年 | 272篇 |
1979年 | 279篇 |
1978年 | 200篇 |
1977年 | 202篇 |
1975年 | 159篇 |
1974年 | 165篇 |
1973年 | 167篇 |
1972年 | 190篇 |
排序方式: 共有10000条查询结果,搜索用时 187 毫秒
51.
E.W. Lees 《Natural resources forum》1993,17(4):288-293
Energy efficiency is often stated to be the most cost-effective measure for satisfying our energy demand with minimal environmental damage. However, the potential energy savings attainable in 'the real world' are frequently overestimated, as is shown in an industrial case study of the glass industry. Nevertheless, there are significant energy savings to be realized, and the role of new technologies in this is important. However, the key to the effective use of new technology for improved energy efficiency is good management and. for best effect, it must be integrated into the normal resource management activities of a company. 相似文献
52.
Taking Sustainable Cities Seriously: a comparative analysis of twenty-four US cities 总被引:1,自引:0,他引:1
Kent E. Portney 《Local Environment》2002,7(4):363-380
After briefly reviewing some conceptual underpinnings of sustainable cities, this paper analyses and compares sustainable cities initiatives in 24 US cities. The central question addressed in the paper is why some cities seem to take sustainability more seriously than others. Numerous demographic, socioeconomic and other characteristics of the cities are correlated with an Index of Taking Sustainability Seriously, which is a composite of some 34 different variables indicating whether each city engages in specific sustainability programmes, policies or activities. Many of the standard explanations, such as the income and wealth of the community, the liberalness of the city and the growth pressures placed on the city, are found to exhibit no correlation with the seriousness of the sustainability effort. What do correlate with the Index are: reliance on manufacturing, where having more residents employed in manufacturing industries is associated with less seriousness; and, the age of the population, where cities with older populations take sustainability more seriously. This has three implications for the future development of sustainable cities. First, some of the cities that might be said to need sustainability programmes the most--cities with heavy manufacturing that are more prone to pollution production--are the least likely to take such programmes seriously. Secondly, as cities' manufacturing bases decline, they should find it increasingly feasible to engage in sustainability initiatives. And, thirdly, as the populations of cities age, policy-makers should also find it easier to support, develop and take seriously sustainability programmes. 相似文献
53.
54.
Reproductive cycle, asexual reproduction, and population dynamics of the fissiparous brittle star, Ophiactis savignyi, which inhabits the exhalant passages of the sponge Haliclona sp. were examined monthly from February 1991 to January 1992 at Wanlitung, southern Taiwan (22°N; 120°E). Mature gametes were found from March to December, but release was mainly in May and June. Sexual recruits were found from May to December, with the highest frequency (14.1% of population) in June. Sexual recruits composed 2.4% of the 1-yr sample. Sex ratio of male to female was 24:1. Fission occurred throughout the year, although the frequency of recently split individuals was lower from January to June (6 to 31%), and higher from July to December (42 to 52%). The occurrence of fission was highest after spawning. Regenerating individuals composed 48.2% of the 1-yr sample. Population density fluctuated greatly during summer due to recruitment by fission and mortality or dispersal due to the stressful environmental conditions. Both sexual and asexual reproduction of O. savignyi were successful at this site. 相似文献
55.
Critics of the Endangered Species Act have asserted that is protects an inordinate number of subspecies and populations, in addition to full species, and that the scientific rationale for listing decisions is absent or weak. We reviewed all U.S. plants and animals proposed for listing or added to the endangered species list from 1985 through 1991 to determine the relative proportion of species, subspecies, and populations, and their rarity at time of listing. Approximately 80% of the taxa added to the list were full species, 18% were subspecies, and 2% were distinct populations segments of more widespread vertebrate species. The proportion of subspecies and populations was considerably higher among birds and mammals than among other groups. The median populations size at time of listing for vertebrate animals was 1075 individuals; for invertebrate animals it was 999. The median population size of a plant at time of listing was less than 120 individuals. Earlier listing of declining species could significantly improve the likelihood of successful recovery, and it would provide land managers and private citizens with more options for protecting vanishing plants and animals at less social or economic cost. 相似文献
56.
J. Malczewski R. Moreno-Sanchez L.A. Bojorquez-Tapia E. Ongay-Delhumeau 《Journal of Environmental Planning and Management》1997,40(3):349-374
This paper is concerned with developing a model for group decision making under multiple criteria. The multiple criteria group decision making (MCGDM)problem involves a set of feasible land use patterns that are evaluated on the basis of multiple, conflicting and noncommensurate criteria by a group of individuals. The model integrates the Analytic Hierarchy Process (AHP) and an integer mathematical programming method. The former provides a tool for structuring the decision problem and determining land suitability for different socio-economicactivities (the uses of land), the latter is used to identify the land use pattern that maximizes consensus among interest groups. The model is used to analyze environmental conflict over land resource allocation in the Cape Region of Mexico. 相似文献
57.
58.
59.
Collaborative policy making has become increasingly significant in environmental management, but it is often evaluated by whether or not agreement is reached and implemented. The most important outcomes of such policy dialogues are often invisible or undervalued when seen through the lens of a traditional, modernist paradigm of government and accountability. These dialogues represent a new paradigm of governance that can be best understood in the light of a complex adaptive system model of society. From this perspective collaborative policy making is a way of making a system more flexible, adaptive and intelligent. The authors document such outcomes in three cases of water policy making in California, including the San Francisco Estuary Project, the CALFED Bay-Delta Program and the Sacramento Area Water Forum. The outcomes include social and political capital, agreed-on information, the end of stalemates, high-quality agreements, learning and change, innovation and new practices involving networks and flexibility. 相似文献
60.
An experimental investigation of explanations for inconsistencies in responses to second offers in double referenda 总被引:1,自引:0,他引:1
Anthony C. Burton Katherine S. Carson Susan M. Chilton W. George Hutchinson 《Journal of Environmental Economics and Management》2003,46(3):472
This paper demonstrates the potential for induced preference experiments to test previously unverified explanations of observed behavior in contingent valuation surveys. The NOAA Panel on Contingent Valuation called for experimental evidence on potential biases in the double referendum format. We test Carson, Groves, and Machina's (Incentives and informational properties of preference questions, Plenary address to the European Association of Resource and Environmental Economists, Oslo, Norway, June 1999) simple cost uncertainty and weighted averaging explanations of inconsistent responses to follow-up offers in such double referenda against a baseline of certainty and truthful preference revelation. The results find evidence to support the Weighted Average hypothesis. Results regarding the cost uncertainty hypothesis are more ambiguous and merit further investigation. 相似文献