首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   42151篇
  免费   367篇
  国内免费   256篇
安全科学   1035篇
废物处理   2376篇
环保管理   5273篇
综合类   5874篇
基础理论   11339篇
环境理论   12篇
污染及防治   9985篇
评价与监测   3325篇
社会与环境   3366篇
灾害及防治   189篇
  2023年   170篇
  2022年   370篇
  2021年   420篇
  2020年   236篇
  2019年   294篇
  2018年   1912篇
  2017年   1839篇
  2016年   1987篇
  2015年   719篇
  2014年   1041篇
  2013年   2784篇
  2012年   1651篇
  2011年   2777篇
  2010年   1945篇
  2009年   1827篇
  2008年   2415篇
  2007年   2674篇
  2006年   1359篇
  2005年   1239篇
  2004年   1160篇
  2003年   1186篇
  2002年   1160篇
  2001年   1148篇
  2000年   811篇
  1999年   515篇
  1998年   397篇
  1997年   391篇
  1996年   401篇
  1995年   485篇
  1994年   404篇
  1993年   350篇
  1992年   380篇
  1991年   360篇
  1990年   332篇
  1989年   327篇
  1988年   297篇
  1987年   245篇
  1986年   250篇
  1985年   252篇
  1984年   284篇
  1983年   265篇
  1982年   272篇
  1981年   221篇
  1980年   166篇
  1979年   184篇
  1978年   162篇
  1977年   134篇
  1975年   141篇
  1973年   168篇
  1972年   143篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
52.
Developers are often required by law to offset environmental impacts through targeted conservation actions. Most offset policies specify metrics for calculating offset requirements, usually by assessing vegetation condition. Despite widespread use, there is little evidence to support the effectiveness of vegetation-based metrics for ensuring biodiversity persistence. We compared long-term impacts of biodiversity offsetting based on area only; vegetation condition only; area × habitat suitability; and condition × habitat suitability in development and restoration simulations for the Hunter Region of New South Wales, Australia. We simulated development and subsequent offsetting through restoration within a virtual landscape, linking simulations to population viability models for 3 species. Habitat gains did not ensure species persistence. No net loss was achieved when performance of offsetting was assessed in terms of amount of habitat restored, but not when outcomes were assessed in terms of persistence. Maintenance of persistence occurred more often when impacts were avoided, giving further support to better enforce the avoidance stage of the mitigation hierarchy. When development affected areas of high habitat quality for species, persistence could not be guaranteed. Therefore, species must be more explicitly accounted for in offsets, rather than just vegetation or habitat alone. Declines due to a failure to account directly for species population dynamics and connectivity overshadowed the benefits delivered by producing large areas of high-quality habitat. Our modeling framework showed that the benefits delivered by offsets are species specific and that simple vegetation-based metrics can give misguided impressions on how well biodiversity offsets achieve no net loss.  相似文献   
53.
54.
Biomethane production through biogas upgrading is a promising renewable energy for some industries which could be part of the equilibrium needed with fossil fuels consumption to achieve a sustainable society. This paper presents a comprehensive list of biogas upgrading technologies focused on carbon dioxide removal as well as recent advances reported by researcher with wide expertise in this topic. Additionally, an extensive costs–performance comparison among the technologies studied is discussed. Among the different alternatives, chemical scrubbing stood out to achieve high biomethane purities while cryogenic technologies proved to be effective against methane losses. Regarding the different costs, water scrubbing and membrane separation seem to be the most affordable techniques.  相似文献   
55.
Environmental Science and Pollution Research - The reduction of estrogen levels, as a result of menopause, is associated with the development of metabolic diseases caused by alterations in...  相似文献   
56.
The use of petroleum-derived products should be avoided regarding the principles of green and sustainable chemistry. The work reported herein, is aimed at the liquefaction of pine shavings for the production of an environmentally-friendly polyol suitable to be used in the formulations of sprayable polyurethane foams. The biopolyols were obtained in high yield and were used to replace those derived from fossil sources, to produce more “greener” polyurethane foams and therefore, less dependent on petroleum sources, since the polyol component was substituted by products resulting from biomass liquefaction. The partial and fully exchange of the polyols was accomplished, and the results compared with a reference foam. The foams were afterward, chemical, physical, morphological, and mechanically characterized. The complete replacement of polyether polyol and polyol polyester has presented some similar characteristics as that used as a reference, validating that the path chosen for the development of more sustainable materials is on the right track for the contribution to a cleaner world.  相似文献   
57.
This study investigated the application of bamboo as a natural composite, in which its potential as a composite material had been examined for 2–6 layers. In precise, the woven bamboo (BW) formed the culm fiber composite with an average of 0.5 mm thickness and 5.0 mm width strip. In addition, this study looked into a specific type of bamboo species known as Gigantochloa Scortechinii (Buluh Semantan), which can be found in Malaysia. This laminated plain BW, which had been reinforced with epoxy (EP), was developed by applying the hand lay-up technique. After that, the specimens were characterized via mechanical analyses, for instance, tensile, flexural, hardness, and impact tests. As a result, the 2-layer BW had displayed rather excellent results chiefly due to the incorporation of epoxy composite, although this is exceptional hardness value.  相似文献   
58.
Distinguishing between soluble and particulate lead in drinking water is useful in understanding the mechanism of lead release and identifying remedial action. Typically, particulate lead is defined as the amount of lead removed by a 0.45-μm filter. Unfortunately, there is little guidance regarding selection of filter membrane material and little consideration to the possibility of the sorption of dissolved lead to the filter. The objective of this work was to examine the tendency of 0.45-μm syringe filter materials to adsorb lead. Tests were performed with water containing 40 and 24 μg/L soluble lead at pH 7 buffered with 50 mg C/L dissolved inorganic concentration (DIC). The amounts of lead sorbed greatly varied by filter, and only two filter types, polypropylene and mixed cellulose esters, performed well and are recommended. Great care must be taken in choosing a filter when filtering soluble lead and interpreting filter results.  相似文献   
59.
The Jain tradition of ecological awareness and sustainability has been well documented over the last 25 years, although its roots lie deep in Indian history, specifically in texts such as the Tattvārtha Sūtra and ācārā?ga Sūtra. This traditional body of knowledge includes a long-standing theory and practice of personal, social and environmental sustainability, addressing such views as the interconnectedness of humans and the laws of nature, the interdependence of everything in the universe, the responsibility of humans to conserve and preserve natural resources, the avoidance of wanton and unnecessary waste generation, and a general aversion to mistreating or abusing the environment. These views encapsulate the lifestyles of some ten million people, including both mendicants and laity. Similarly, Maharishi Vedic Science, the systematic exploration and practical application of the Veda and Vedic Literature as taught by Maharishi Mahesh Yogi, makes a compelling case for establishing the unity of human life with nature and for promoting actions which guarantee both the protection of nature and protection by it. The purpose of this paper is to examine the relationship between the principles of sustainability in Jainism and the corresponding viewpoint of Maharishi Vedic Science, including supporting scientific evidence of its application, and to posit their contribution to a sustainable world future.  相似文献   
60.
Dissipation and decontamination of chlorantraniliprole (Coragen 18.5 SC) in brinjal and okra fruits were studied following field application at single and double doses of 30 and 60 g ai ha?1, and the residues of the insecticide was estimated using LC-MS/MS. Initial residues of chlorantraniliprole at single and double doses on the fruits of brinjal were 0.72 and 1.48 mg kg?1, while on okra fruits, the residues were 0.48 and 0.91 mg kg?1, respectively. The residues reached below detectable level of 0.01 mg kg?1 on the 10th day. Half-life of chlorantraniliprole at 30 and 60 g ai ha?1 on brinjal was 1.58 and 1.80 days with the calculated waiting period of 0.69 and 2.38 days, whereas on okra, the values were 1.60 and 1.70 and 0 and 1.20 days, respectively. The extent of removal of chlorantraniliprole using simple decontaminating techniques at 2 h and 3 days after spraying was 40.99–91.37 % and 29.85–89.12 %, respectively, from brinjal fruits and 47.78–86.10 % and 41.77–86.48 %, respectively, from okra fruits.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号