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   791篇
  免费   33篇
  国内免费   38篇
安全科学   95篇
废物处理   18篇
环保管理   86篇
综合类   186篇
基础理论   389篇
污染及防治   29篇
评价与监测   23篇
社会与环境   30篇
灾害及防治   6篇
  2024年   1篇
  2023年   5篇
  2022年   10篇
  2021年   12篇
  2020年   13篇
  2019年   8篇
  2018年   9篇
  2017年   16篇
  2016年   23篇
  2015年   15篇
  2014年   17篇
  2013年   29篇
  2012年   34篇
  2011年   49篇
  2010年   45篇
  2009年   48篇
  2008年   69篇
  2007年   70篇
  2006年   70篇
  2005年   51篇
  2004年   40篇
  2003年   29篇
  2002年   17篇
  2001年   18篇
  2000年   24篇
  1999年   30篇
  1998年   19篇
  1997年   20篇
  1996年   20篇
  1995年   18篇
  1994年   12篇
  1993年   5篇
  1992年   5篇
  1990年   2篇
  1989年   2篇
  1988年   1篇
  1985年   1篇
  1982年   1篇
  1979年   1篇
  1977年   2篇
  1975年   1篇
排序方式: 共有862条查询结果,搜索用时 0 毫秒
401.
基于高压电容器振动试验夹具材料的选用与设计   总被引:1,自引:0,他引:1  
崔松建  彭红  陈静 《环境技术》2010,30(5):27-29
介绍了一种基于高压电容器性能检测及振动试验所需的夹具,从夹具材料的选取、结构设计和刚度要求进行了设计,分析了该夹具在制造过程中存在的关键问题及解决方法,并在振动试验中加以验证。  相似文献   
402.
通过试验对炼油废水絮凝剂进行了筛选。结果表明 ,有机高分子絮凝剂 (PAM、HL - 70 4 )与无机絮凝剂 (PAC)复配显著提高了油类和COD的去除率 ,复配絮凝剂具有投加量少、适用性强等优点。  相似文献   
403.
生态补偿对象空间选择的研究进展及展望   总被引:3,自引:1,他引:3  
生态补偿作为一种将外在的、非市场环境服务转化为当地参与者提供生态系统服务的财政激励机制而备受世界关注。为了全面认识国际生态补偿对象空间选择的状况与成果,促进国际生态补偿对象空间选择研究的交流与合作,论文在分析国际相关理论和实践研究的基础上,概括介绍了生态补偿对象空间选择的相关概念和研究背景,对不同补偿对象选择方案进行了归纳梳理和比较分析,简要介绍了得分函数法、距离函数法和GAP分析法等研究方法,比较分析了研究方法的优缺点,最后提出了思考和展望:选择方案的设计既要注重资金效益,又要兼顾公平;努力建立生态补偿效果的评价机制,逐步完善生态补偿对象选择方案,健全生态补偿机制。  相似文献   
404.
从海洋自然资源支撑能力、环境制约因子、与相关规划的符合性等方面提出了滨海重化工项目选址阶段应着重考虑的海洋要素。只有在选址阶段综合考虑资源、环境、政策法规等因素,才能兼顾经济快速发展和可持续发展,避免出现海洋资源约束和生态环境约束两大瓶颈,取得经济发展与环境保护双赢。  相似文献   
405.
Genetic variability among males is a necessary precondition for the evolution of female choice based on indirect genetic benefits. In addition to mutations and host–parasite cycles, migration of locally adapted individuals offers an explanation for the maintenance of genetic variability. In a previous study, conducting a reciprocal transplant experiment on a grasshopper, Chorthippus biguttulus, we found that environmental conditions significantly influenced not only body condition but also an important trait of male calling song, the amplitude of song. Although not significant, all other analysed physical and courtship song traits and attractiveness were superior in native than in transferred males. Thus, we concluded that local adaptation has a slight but consistent influence on a range of traits in our study populations, including male acoustic attractiveness. In our present study, we scanned male grasshoppers from the same two populations for amplification fragment length polymorphism (AFLP) loci connected with acoustic attractiveness to conspecific females. We found greater differences in allele frequencies between the two populations, for some loci, than are expected from a balance between drift and gene flow. These loci are potentially connected with locally adapted traits. We examined whether these alleles show the proposed genotype environment interaction by having different associations with attractiveness in the two populations. One locus was significantly related to sexual attractiveness; however, this was independent of the males’ population affiliation. Future research on the evolution of female choice will benefit from knowledge of the underlying genetic architecture of male traits under intraspecific sexual selection, and the ‘population genomics’ approach can be a powerful tool for revealing this structure.  相似文献   
406.
个体防护装备在受限空间作业中的选择配备与使用管理   总被引:2,自引:1,他引:2  
近年来,受限空间伤害事故频发,已引起各相关部门的重视。个体防护装备的合理正确选用在避免受限空间伤害事故的发生上起着至关重要的作用。本文通过典型案例,仅从个体防护装备的配备和管理角度分析事故的致因,并根据受限空间内所存在的各种危害类别及形式探讨个体防护装备的选配以及合理的使用与管理,以期能够有效地防止或减少受限空间内作业伤害事故的发生。  相似文献   
407.
污染场地修复技术的分类、应用与筛选方法探讨   总被引:13,自引:1,他引:13  
污染场地修复是污染场地管理的重要环节,目前该领域在我国还处于起步阶段,全面了解污染场地修复技术的分类、适用范围、筛选程序以及应用现状与趋势,对于在我国开展污染场地的修复与管理工作具有重要意义. 系统地论述了污染场地修复技术的分类方法,以美国超级基金场地修复为例,阐述了目前不同污染场地修复技术的应用状况,并对一些常用的污染场地修复技术进行了参数比较. 同时,介绍了美国超级基金污染场地修复技术的筛选方法与技术政策. 通过对数10年来超级基金场地修复技术的选择与应用进行分析,提出我国污染场地修复的对策和建议.   相似文献   
408.
Ultraviolet (UV) reflectance of the plumage is common in birds and plays an important role in sexual signalling. Recently, it has been proposed that birds are able to modify plumage UV reflectance by the application of uropygial gland secretion. Based on a survey of the optical properties of this secretion from 51 species belonging to 12 avian orders, we show that two main types of uropygial secretions exist, one predominantly found in passerines and one in non-passerines, both reducing relative UV reflectance of a white background (Teflon™ tape). We quantified how each type of secretion (exemplified by blue tit and mallard) affected feather UV reflectance. Both secretions reduced overall brightness and relative UV reflectance of white mallard feathers but hardly affected the reflectance of UV/blue blue tit crown feathers. According to models of avian colour vision, changes in reflectance due to application of the secretion were at or below the discrimination threshold of most birds. We conclude that the uropygial secretion is unlikely to play a major role in modifying plumage UV reflectance. However, the optical properties of the uropygial secretion may have been selected to interfere as little as possible with visual signaling through plumage reflectance. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.  相似文献   
409.
Efficiency,costs and trade-offs in marine reserve system design   总被引:1,自引:0,他引:1  
With marine biodiversity conservation the primary goal for reserve planning initiatives, a site's conservation potential is typically evaluated on the basis of the biological and physical features it contains. By comparison, socio-economic information is seldom a formal consideration of the reserve system design problem and generally limited to an assessment of threats, vulnerability or compatibility with surrounding uses. This is perhaps surprising given broad recognition that the success of reserve establishment is highly dependent on widespread stakeholder and community support. Using information on the spatial distribution and intensity of commercial rock lobster catch in South Australia, we demonstrate the capacity of mathematical reserve selection procedures to integrate socio-economic and biophysical information for marine reserve system design. Analyses of trade-offs highlight the opportunities to design representative, efficient and practical marine reserve systems that minimise potential loss to commercial users. We found that the objective of minimising the areal extent of the reserve system was barely compromised by incorporating economic design constraints. With a small increase in area (<3%) and boundary length (<10%), the economic impact of marine reserves on the commercial rock lobster fishery was reduced by more than a third. We considered also how a reserve planner might prioritise conservation areas using information on a planning units selection frequency. We found that selection frequencies alone were not a reliable guide for the selection of marine reserve systems, but could be used with approaches such as summed irreplaceability to direct conservation effort for efficient marine reserve design.  相似文献   
410.
Wild geese foraging on farmland cause increasing conflicts with agricultural interests, calling for a strategic approach to mitigation. In central Norway, conflicts between farmers and spring-staging pink-footed geese feeding on pastures have escalated. To alleviate the conflict, a scheme by which farmers are subsidized to allow geese to forage undisturbed was introduced. To guide allocation of subsidies, an ecological-based ranking of fields at a regional level was recommended and applied. Here we evaluate the scheme. On average, 40 % of subsidized fields were in the top 5 % of the ranking, and 80 % were within the top 20 %. Goose grazing pressure on subsidized pastures was 13 times higher compared to a stratified random selection of non-subsidized pastures, capturing 67 % of the pasture feeding geese despite that subsidized fields only comprised 13 % of the grassland area. Close dialogue between scientists and managers is regarded as a key to the success of the scheme.  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