全文获取类型
收费全文 | 34456篇 |
免费 | 286篇 |
国内免费 | 324篇 |
专业分类
安全科学 | 888篇 |
废物处理 | 1517篇 |
环保管理 | 3778篇 |
综合类 | 6583篇 |
基础理论 | 8557篇 |
环境理论 | 16篇 |
污染及防治 | 8949篇 |
评价与监测 | 2512篇 |
社会与环境 | 2079篇 |
灾害及防治 | 187篇 |
出版年
2022年 | 329篇 |
2021年 | 314篇 |
2020年 | 209篇 |
2019年 | 287篇 |
2018年 | 538篇 |
2017年 | 542篇 |
2016年 | 827篇 |
2015年 | 602篇 |
2014年 | 943篇 |
2013年 | 2623篇 |
2012年 | 1098篇 |
2011年 | 1446篇 |
2010年 | 1232篇 |
2009年 | 1262篇 |
2008年 | 1461篇 |
2007年 | 1524篇 |
2006年 | 1357篇 |
2005年 | 1166篇 |
2004年 | 1116篇 |
2003年 | 1092篇 |
2002年 | 1070篇 |
2001年 | 1374篇 |
2000年 | 949篇 |
1999年 | 621篇 |
1998年 | 410篇 |
1997年 | 400篇 |
1996年 | 445篇 |
1995年 | 449篇 |
1994年 | 431篇 |
1993年 | 359篇 |
1992年 | 400篇 |
1991年 | 380篇 |
1990年 | 377篇 |
1989年 | 356篇 |
1988年 | 331篇 |
1987年 | 255篇 |
1986年 | 248篇 |
1985年 | 261篇 |
1984年 | 287篇 |
1983年 | 267篇 |
1982年 | 308篇 |
1981年 | 258篇 |
1980年 | 210篇 |
1979年 | 241篇 |
1978年 | 227篇 |
1977年 | 204篇 |
1976年 | 204篇 |
1975年 | 175篇 |
1974年 | 190篇 |
1967年 | 172篇 |
排序方式: 共有10000条查询结果,搜索用时 296 毫秒
991.
Local rural and indigenous communities have assumed increasing responsibility for conservation within and between areas buffering the impacts of agricultural or resource‐extraction zones and protected areas. Empowering local communities as central partners in conservation and climate‐change mitigation has allowed many people to gain access to land and citizenship rights but has provided limited improvements in access to social services and economic opportunities even as expectation about their role as environmental stewards grows. These expectations, however, are inconsistent with reality. We conducted multiple field studies in Brazil since the mid‐1980s to illustrate the discrepancies between conservation programs and local conditions and expectations. We suggest that public policies and conservation programs should not delegate responsibility for managing protected areas to local and indigenous communities without considering local needs and expectations and locals’ attitudes toward conservation. In other words, behavior that maintains or improves the environment should not be treated as traditional based on the expectations of outsiders. Framing local populations as traditional environmentalists creates contradictions and frustrations for local populations and for conservation professionals and policy makers. 相似文献
992.
Kyoung S. Ro Patrick G. Hunt Michael A. Jackson David L. Compton Scott R. Yates Keri Cantrell SeChin Chang 《Waste management (New York, N.Y.)》2014,34(8):1520-1528
Manure-derived biochar is the solid product resulting from pyrolysis of animal manures. It has considerable potential both to improve soil quality with high levels of nutrients and to reduce contaminants in water and soil. However, the combustible gas produced from manure pyrolysis generally does not provide enough energy to sustain the pyrolysis process. Supplementing this process may be achieved with spent agricultural plastic films; these feedstocks have large amounts of available energy. Plastic films are often used in soil fumigation. They are usually disposed in landfills, which is wasteful, expensive, and environmentally unsustainable. The objective of this work was to investigate both the energetics of co-pyrolyzing swine solids with spent plastic mulch films (SPM) and the characteristics of its gas, liquid, and solid byproducts. The heating value of the product gas from co-pyrolysis was found to be much higher than that of natural gas; furthermore, the gas had no detectable toxic fumigants. Energetically, sustaining pyrolysis of the swine solids through the energy of the product gas could be achieved by co-pyrolyzing dewatered swine solids (25% m/m) with just 10% SPM. If more than 10% SPM is used, the co-pyrolysis would generate surplus energy which could be used for power generation. Biochars produced from co-pyrolyzing SPM and swine solid were similar to swine solid alone based on the surface area and the 1H NMR spectra. The results of this study demonstrated the potential of using pyrolysis technology to manage two prominent agricultural waste streams (SPM and swine solids) while producing value-added biochar and a power source that could be used for local farm operations. 相似文献
993.
Bizo Maria L. Nietzsche Sandor Mansfeld Ulrich Langenhorst Falko Majzlan Juraj Göttlicher Jörg Ozunu Alexandru Formann Steffi Krause Katrin Kothe Erika 《Environmental science and pollution research international》2017,24(16):14455-14462
Environmental Science and Pollution Research - The development of mycorrhized pine seedlings grown in the presence of lead was assessed in order to investigate how higher plants can tolerate lead... 相似文献
994.
S. V. Otari R. M. Patil N. H. Nadaf S. J. Ghosh S. H. Pawar 《Environmental science and pollution research international》2014,21(2):1503-1513
A novel approach for the green synthesis of silver nanoparticles (AgNPs) from aqueous solution of AgNO3 using culture supernatant of phenol degraded broth is reported in this work. The synthesis was observed within 10 h, and AgNPs showed characteristic surface plasmon resonance around 410 nm. Spherical nanoparticles of size less than 30 nm were observed in transmission electron microscopy. X-ray diffraction pattern corresponding to 111, 200, 220, and 311 revealed the crystalline nature of the as-formed nanoparticles. It was found that the colloidal solution of AgNP suspensions exhibited excellent stability over a wide range of ionic strength, pH, and temperature. The effect of pH and ionic strength indicated that stabilization is due to electrostatic repulsion arising from the negative charge of the conjugate proteins. The AgNPs showed highly potent antimicrobial activity against Gram-positive, Gram-negative, and fungal microorganisms. The as-prepared AgNPs showed excellent catalytic activity in reduction of 4-nitrophenol to 4-aminophenol by NaBH4. By manufacturing magnetic alginate beads, the reusability of the AgNPs for the catalytic reaction has been demonstrated. 相似文献
995.
Journal of Polymers and the Environment - To optimize the phase separation temperature of poly (N-isopropylacrylamide) two monomers have been used to fabricate a series of three functional and... 相似文献
996.
997.
Christer Ahlström Maria Gink Lövgren Mats Nilsson Tania Dukic Willstrand Anna Anund 《International journal of occupational safety and ergonomics》2019,25(3):377-385
City bus drivers spend hours driving under time pressure, in congested traffic and in a monotonous sitting position. This leads to unhealthy working conditions, especially in terms of physical and psychological stress. The aim of this study is to investigate whether an active steering system can alleviate the musculoskeletal stress involved in manoeuvring a bus. Twenty bus drivers drove a city bus equipped with the Volvo dynamic steering (VDS) support system in real traffic. Steering effort was evaluated with electromyography and with a questionnaire. Compared to baseline, VDS significantly reduced the required muscle activity by on average 15–25% while turning, and up to 68% in the part of the manoeuvre requiring maximum effort. The bus drivers believed that VDS will help reduce neck and shoulder problems, and they expressed a desire to have VDS installed in their own bus. 相似文献
998.
999.
1000.
R. Hickisch T. Hodgetts P. J. Johnson C. Sillero-Zubiri K. Tockner D.W. Macdonald 《Conservation biology》2019,33(5):1151-1163
Conservation planners need reliable information on spatial patterns of biodiversity. However, existing data sets are skewed because some ecosystems, taxa, and locations are underrepresented. We determined how many articles have been published in recent decades on the biodiversity of different countries and their constituent provinces. We searched the Web of Science catalogues Science Citation Index (SCI) and Social Science Citation Index (SSCI) for biodiversity-related articles published from 1993 to 2016 that included country and province names. We combined data on research publication frequency with other provincial-scale factors hypothesized to affect the likelihood of research activity (i.e., economic development, human presence, infrastructure, and remoteness). Areas that appeared understudied relative to the biodiversity expected based on site climate likely have been inaccessible to researchers for reasons, notably armed conflict. Geographic publication bias is of most concern in the most remote areas of sub-Saharan Africa and South America. Our provincial-scale model may help compensate for publication biases in conservation planning by revealing the spatial extent of research needs and the low cost of redoing this analysis annually. 相似文献