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   132篇
  免费   2篇
  国内免费   8篇
安全科学   24篇
环保管理   7篇
综合类   64篇
基础理论   29篇
污染及防治   3篇
评价与监测   7篇
社会与环境   5篇
灾害及防治   3篇
  2023年   1篇
  2022年   5篇
  2021年   6篇
  2020年   3篇
  2019年   6篇
  2018年   2篇
  2017年   9篇
  2016年   4篇
  2015年   3篇
  2014年   7篇
  2013年   5篇
  2012年   6篇
  2011年   9篇
  2010年   5篇
  2009年   7篇
  2008年   5篇
  2007年   9篇
  2006年   2篇
  2005年   6篇
  2004年   4篇
  2003年   5篇
  2002年   3篇
  2001年   5篇
  2000年   5篇
  1999年   3篇
  1997年   3篇
  1996年   2篇
  1995年   2篇
  1994年   4篇
  1993年   4篇
  1992年   1篇
  1990年   1篇
排序方式: 共有142条查询结果,搜索用时 31 毫秒
111.
蕨类植物芒萁(Dicranopteris dichotoma)是我国南方红壤侵蚀区重要的水土保持植物,但目前氮添加对芒萁叶功能性状及其基部土壤化学性质以及这二者之间关系的影响尚不清楚.以芒萁作为研究对象,采用盆栽实验,设置CK(0 g m-2 a-1)、N1(1.1 g m-2 a-1)、N2(2.3 g m-2 a-...  相似文献   
112.
以阜阳为例,分析城乡交通一体化建设给阜阳城区交通安全管理带来的挑战,通过对阜阳市城区路网结构、交通参与者的交通安全意识和交通安全管理压力3个方面的实地调查,得出传统交通管理模式已不能满足城乡交通一体化建设带来的新交通形势需要的结论。在借鉴国外发达国家交通安全管理对策的基础上,提出应对城乡交通一体化建设的交通安全管理策略:挖掘路网潜能治理混合交通策略、城乡交通一体化建设针对性管理策略和发展智能交通系统实现交通安全管理升级策略,使交通安全管理能够有效应对城乡一体化建设带来的各种挑战。  相似文献   
113.
Indicator or ”good genes” models of sexual selection predict that mating preferences allow females to choose mates that are genetically superior. Female gray tree frogs (Hyla versicolor) prefer male advertisement calls of long call duration, which can be indicators of enhanced offspring growth performance. We tested the effects of father’s call duration and the presence of a caged predator (dragonfly naiad) on tadpole activity and growth in a factorial experiment, controlling for maternal and environmental effects. The effect of food availability (a repeated measure) on tadpole activity was also examined. Tadpoles responded to predator presence and to high food availability by decreasing activity and feeding. Tadpoles exposed to a caged predator were smaller after 14 days than those exposed to an empty cage, suggesting that spending less time feeding carries the cost of reduced growth. Offspring of males with long versus short calls responded similarly to the presence of a predator. Nonetheless, offspring of long-calling males spent more time feeding than did offspring of short-calling males, except when a predator was present but no food was available. Increased time spent feeding may contribute to enhanced offspring growth and, therefore, to the indirect benefit that a female may realize by selecting a mate with long calls. However, because the behavioral differences depended on the environment, and because the fitness consequences of such behavioral differences should also vary with the environment, the benefit of mating with a long-calling male may depend on the conditions encountered by the offspring. Received: 15 February 2000 / Revised: 24 September 2000 / Accepted: 16 October 2000  相似文献   
114.
The infinite dimensional model (IDM) is an approach that has been developed for the analyses of phenotypic variation in function valued traits such as growth trajectories and continuous reaction norms. This model is particularly suited for the analysis of the potential and the constraints for growth to evolve under selection on body size. Despite of its applicability to a broad range of study systems IDM has only been applied in a handful of studies, as it is mathematically demanding for scientists not familiar with quantitative genetics methods. Here, we present a user-friendly R implementation of IDM, demonstrate its performance with growth data on nine-spined stickleback (Pungitius pungitius). In addition to rearing experiments, individual based size-at-age trajectories are often measured in wild in mark-recapture studies or estimated retrospectively from scales or bones. Therefore, our R implementation of IDM should be applicable to many studies conducted in wild and in a lab, and be useful by making the methodologically challenging IDM approach more easily accessible also in the fields where quantitative genetics methods are less standardly used.  相似文献   
115.
刘爱华  吴超  蔡康旭 《火灾科学》2003,12(4):230-233
综述了国内外喷注型浆体防煤自燃技术的现状和发展趋势,通过实验,得出塑性石膏浆的配制方案和堵漏风效果。结果表明:在井下高湿环境中,塑性石膏浆不仅具有良好的附着性、充填性和保塑性,而且用料单一、成本较低、无毒无害,满足防治煤炭自燃对喷注型材料的基本要求,有利于提高煤矿生产的安全保障程度。  相似文献   
116.
梁子湖流域水环境功能区划及水质现状分析   总被引:1,自引:0,他引:1  
“水是生命之源,生产之本。”近几十年来,由于人类活动对自然界的影响越来越大,水环境的污染问题也越来越突出,其造成的危害和影响越来越受到人们的关注。水资源总量是有限的,因此合理的规划开发利用水资源显得尤为重要。本文针对梁子湖流域存在的水环境水质恶化的问题,依据其水环境功能区划,通过对水质现状的监测,利用透明度、DO、BOD、COD、NH3-N、TP六个指标作为梁子湖水质研究的主要水质指标,并对监测结果进行分析,依据其检测结果进行流域控制单元的划分,同时加强水质管理,从而达到优化梁子湖流域水环境区划功能的目的,并对做好水资源保护工作有着重要的现实指导意义。  相似文献   
117.
Abstract: We tested the hypothesis that variation in the sensitivity of animals to habitat change is explained by ecological traits (life‐history traits, trophic level, and mobility). We measured the sensitivity of insectivorous mammals (shrews and bats) and their prey (arthropods active at the soil surface and nocturnal aerial arthropods) to three aspects of agricultural intensification in a matched‐pair experimental design: increased use of agrochemicals (comparison of organic and conventional cereal crops, with pairing for the size of the boundary hedge), change in grassland management from hay to silage (with pairing for the size of the boundary hedge), and increased field size due to hedgerow loss (with boundary‐field comparisons as a proxy). We assessed the sensitivity of taxa as the difference in their relative abundance between pairs of high‐ and low‐intensity sites for each aspect of agricultural intensification. We used phylogenetically informed analyses to explore cross‐species relationships between our measures of sensitivity and seven ecological traits of animals (e.g., trophic level, mobility, and reproductive rate). Several traits were related to the sensitivity of animals to agricultural intensification. These traits were mainly associated with fast life histories (high reproductive output and low trophic level) and low mobility. Trophic level of adults was related to sensitivity to habitat change for all three aspects of agricultural intensification, but the direction of the relationship differed between the three aspects of intensification. The significance of the relationship between other ecological traits and sensitivity to intensification varied for the three aspects of agricultural intensification. Our results show that some ecological traits can be used to preselect taxa that are predicted to be sensitive to habitat change, and their sensitivity can be tested empirically for use as biotic indicator taxa. Understanding which traits are related to sensitivity to habitat change is vital because sensitivity is important in determining a taxon's ability to survive in dynamic environments.  相似文献   
118.
对注册安全工程师定位并充分发挥其作用的探讨   总被引:13,自引:9,他引:4  
自2002年9月在我国实施注册安全工程师执业资格制度以来,已有11044人获得《中华人民共和国注册安全工程师执业资格证书》。可以预见,今后几年的时间里,将有数万人取得注册安全工程师执业资格。但是,如何解决注册安全工程师的定位问题,如何提高注册安全工程师的地位和充分发挥注册安全工程师的作用,以及如何推进和完善注册安全工程师执业资格制度,仍需继续出台一系列的政策。笔者就注册安全工程师的定位问题以及如何充分发挥注册安全工程师的作用进行了探讨。  相似文献   
119.
随着社会的进步和石化行业向着高科技高效益的迅猛发展,人们对生存环境和工作环境的质量要求越来越高。通过介绍现代石化建筑的HSE理念,探讨现代石化建筑的设计思想及手法和努力创造“以人为本”具有人性化特征的工作场所,说明现代石化建筑设计应该致力于满足人们对建筑物的安全健康与环境的要求。  相似文献   
120.
划定生态保护红线,是生态文明建设的一项重要任务,对维护国家和区域生态安全及经济社会可持续发展具有重要的战略意义。目前,城市化发展中面临着突出生态环境问题,在城市层面开展生态保护红线的划定工作显得更加紧迫。但现阶段生态保护红线的划分技术上仍处于不断探索与完善阶段。基于此,文章以湖北省宜昌市为例,利用RS和GIS技术,采用"识-评-落-融-分"的技术流程,提出了一套城市生态保护红线体系与划分方法。结果表明:宜昌市生态保护红线体系划分为3个层级:生态保护红线区、生态保护黄线区和生态保护绿线区;生态保护红线区、黄线区和绿线区分别占全市面积的48.83%、31.50%和19.67%。  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