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   15832篇
  免费   144篇
  国内免费   116篇
安全科学   324篇
废物处理   638篇
环保管理   1862篇
综合类   3627篇
基础理论   3614篇
环境理论   6篇
污染及防治   3950篇
评价与监测   1012篇
社会与环境   1013篇
灾害及防治   46篇
  2022年   103篇
  2021年   121篇
  2019年   101篇
  2018年   200篇
  2017年   191篇
  2016年   309篇
  2015年   237篇
  2014年   358篇
  2013年   1080篇
  2012年   399篇
  2011年   608篇
  2010年   469篇
  2009年   548篇
  2008年   632篇
  2007年   671篇
  2006年   601篇
  2005年   502篇
  2004年   526篇
  2003年   516篇
  2002年   486篇
  2001年   619篇
  2000年   389篇
  1999年   290篇
  1998年   183篇
  1997年   200篇
  1996年   220篇
  1995年   230篇
  1994年   230篇
  1993年   213篇
  1992年   195篇
  1991年   205篇
  1990年   196篇
  1989年   169篇
  1988年   168篇
  1987年   154篇
  1986年   153篇
  1985年   148篇
  1984年   169篇
  1983年   167篇
  1982年   172篇
  1981年   144篇
  1980年   132篇
  1979年   123篇
  1978年   134篇
  1977年   115篇
  1976年   103篇
  1975年   107篇
  1974年   118篇
  1971年   98篇
  1967年   101篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
This paper focusses on a conceptual overview of ways to address a comprehensive analysis of ecosystem services (ES) in a country as large and heterogeneous as Russia. As a first step, a methodology for assessing the services for the federal subjects of Russia was chosen, i.e., its constituent provinces and similar entities, in physical terms. Russia harbors a great diversity of natural conditions and ecosystems which are suppliers of ES, and likewise a variety of the socio-economic conditions that shape the demand for these services and their consumption. The methodological approach described permits several important tasks to be addressed: the evaluation of the degree of satisfaction of people’s needs for ES, the identification of ecological donor and acceptor regions, and zoning of the country’s territory for ES assessment. The next step is to prepare a prototype of a National Report on ES in Russia, for which we are presenting the planned structure.  相似文献   
82.
83.
84.
85.
86.
The aim of this study was to determine the level of 26 polycyclic aromatic hydrocarbons (PAHs) at parking garages and to provide the necessary annual information based on occupational inhalation exposure and non-occupational inhalation exposure, which carry risks for the environment. For this purpose, 22 samples were collected continuously from both gas and particulates phase PAHs from two parking garages at Konya City Center, Turkey. The exposure-based risk of these samples was evaluated using concentrations of the carcinogenic PAH compounds. None of the 26 PAHs measured had values exceeding the recommended exposure limits (RELs) standard values for inhalation rate recommended by the World Health Organization (WHO). Exposure levels of gas and particulate PAHs for the occupational group and the public (children and adults who spend time in shopping centers) were found to be 0.07–28.24 μgm?3 and 0.05–5.753 μgm?3, respectively, representing levels two to four times higher than those at the control site. Maximum daily inhalation of B[a]Py was estimated at 1.33 ngd?1 for exposure of the public and as 274 ngd?1 for the occupational group. It is believed that traffic makes a substantial contribution to the PAH profile, which had relatively high concentrations of naphthalene (Napth) and coronene (Coro). Highly carcinogenic dibenzo(a,l)pyrene (B[al]Pyre) was found in the ambient air at two parking garages. Napth and phenanthrene (Phen) were the main compounds found in nearly all the tested samples. In this study, benzo[e]pyrene (B[e]Py) was used as a reference for PAHs because its concentration is stable and does not change seasonally. Considering the importance of these compounds in relation to human health, the aim of this work was to characterize and quantify the more toxic PAHs in parking garages. Conducting PAH sampling and their chemical analysis is very costly and labor intensive. This study produced data that can be a powerful tool for environmental forensics.  相似文献   
87.
Environmental Science and Pollution Research - Hydroxyurea (HDU), a class of antineoplastic drugs, has a powerful efficacy in the treatment of several types of malignancies. However, it has...  相似文献   
88.
The structure of commercial sable samples from the Cis-Ural region was studied taking into account hunting method (shooting or trapping). The proportion of adult animals was found to be significantly lower in samples taken during the first half of the hunting season, compared to the second half, indicating predominant harvesting of young animals. To estimate the degree of hunting selectivity (I), the ratios of demographic groups among shot and trapped animals were calculated. The results confirmed the fact of selective hunting for underyearlings both by shooting (I = 1.49–1.60 for the Cis-Ural region and I = 2.46–3.37 for the Western Sayan Mountains) and by trapping (I = 2.80–4.37), especially during the first half of winter. Samples taken during the second half of the season were characterized by prevalence of adult animals making up the reproductive core of the population (I = 1.43–2.07). It is considered that the process of reproduction in Cis-Ural sable populations in the 1960s to 1980s was stimulated by intensive commercial hunting. To maintain reproduction of sable populations at a safe level, it is necessary to reduce the period of hunting in the first quarter of the year. It is proposed to use the phenomenon of hunting selectivity for managing sable populations, regulating their exploitation, and improving the economic productivity of habitats. Commercial hunting in terms of its impact on the population can act as a factor of conscious or unconscious artificial selection.  相似文献   
89.
The afforestation of arid lands faces many challenges, and perhaps the most important key for success is choosing one or more species that are adapted well for local environmental conditions. We explored species that would be suitable for the steppe region of Central Anatolia. Intensive site preparation included ripping the subsoil (to 80 cm) and plowing the upper soil before planting seedlings of Elaeagnus angustifolia, Robinia pseudoacacia, Fraxinus angustifolia, and Pinus nigra were used as tree species. We also tested the success of several shrub species: Amygdalus orientalis, Calligonum polygonoides, and Spartium junceum. After five growing seasons, E. angustifolia showed the highest survival, with 80% of planted seedlings remaining. For the shrubs, A. orientalis was the most successful species with a 95% survival rate. Broad-leaved trees grew a cumulative average of 34 cm in height in 5 years, whereas P. nigra seedings grew only 9 cm. The greatest height growth occurred in the shrubs, with A. orientalis gaining 40 cm in height in 5 years. Overall, E. angustifolia and A. orientalis appeared best suited for afforestation in these areas. R. pseodoacacia and F. angustifolia may also be used as alternative species.  相似文献   
90.
Payments to compensate landowners for carrying out costly land‐use measures that benefit endangered biodiversity have become an important policy instrument. When designing such payments, it is important to take into account that spatially connected habitats are more valuable for many species than isolated ones. One way to incentivize provision of connected habitats is to offer landowners an agglomeration bonus, that is, a bonus on top of payments they are receiving to conserve land if the land is spatially connected. Researchers have compared the cost‐effectiveness of the agglomeration bonus with 2 alternatives: an all‐or‐nothing, agglomeration payment, where landowners receive a payment only if the conserved land parcels have a certain level of spatial connectivity, and a spatially homogeneous payment, where landowners receive a payment for conserved land parcels irrespective of their location. Their results show the agglomeration bonus is rarely the most cost‐effective option, and when it is, it is only slightly better than one of the alternatives. This suggests that the agglomeration bonus should not be given priority as a policy design option. However, this finding is based on consideration of only 1 species. We examined whether the same applied to 2 species, one for which the homogeneous payment is best and the other for which the agglomeration payment is most cost‐effective. We modified a published conceptual model so that we were able to assess the cost‐effectiveness of payment schemes for 2 species and applied it to a grassland bird and a grassland butterfly in Germany that require the same habitat but have different spatial‐connectivity needs. When conserving both species, the agglomeration bonus was more cost‐effective than the agglomeration and the homogeneous payment; thus, we showed that as a policy the agglomeration bonus is a useful conservation‐payment option.  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