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   10601篇
  免费   1042篇
  国内免费   1722篇
安全科学   2262篇
废物处理   232篇
环保管理   1871篇
综合类   5135篇
基础理论   1285篇
环境理论   16篇
污染及防治   557篇
评价与监测   752篇
社会与环境   662篇
灾害及防治   593篇
  2024年   55篇
  2023年   227篇
  2022年   386篇
  2021年   463篇
  2020年   429篇
  2019年   425篇
  2018年   354篇
  2017年   436篇
  2016年   524篇
  2015年   523篇
  2014年   577篇
  2013年   767篇
  2012年   833篇
  2011年   946篇
  2010年   607篇
  2009年   639篇
  2008年   548篇
  2007年   679篇
  2006年   597篇
  2005年   482篇
  2004年   369篇
  2003年   363篇
  2002年   310篇
  2001年   250篇
  2000年   198篇
  1999年   201篇
  1998年   133篇
  1997年   145篇
  1996年   128篇
  1995年   94篇
  1994年   107篇
  1993年   79篇
  1992年   63篇
  1991年   53篇
  1990年   41篇
  1989年   37篇
  1988年   40篇
  1987年   22篇
  1986年   14篇
  1985年   21篇
  1984年   13篇
  1983年   12篇
  1982年   25篇
  1981年   20篇
  1980年   19篇
  1979年   20篇
  1978年   14篇
  1977年   10篇
  1972年   18篇
  1971年   20篇
排序方式: 共有10000条查询结果,搜索用时 156 毫秒
631.
盐穴地下储气库事故统计及风险分析   总被引:3,自引:1,他引:2  
借鉴输气管道和二氧化碳地下封存设施的风险评价方法,结合盐穴地下储气库的事故统计分析,对储气库系统中的潜在风险因素进行12大类、35小类的初步分类,并归纳总结了盐穴地下储气库的3种主要事故类型。采用事故树分析的风险评价方法,对13种主要风险因素进行风险识别。在此基础上,提出定量风险评价的重要工程模型,其包括气体水合物模型、盐穴稳定性评价模型以及气体泄漏模型。该风险分析方法和工程模型有助于定量评价盐穴地下储气库的主要风险因素,为储库的安全稳定运行提供了科学依据。  相似文献   
632.
从技术角度分析地铁坍塌事故发生的机理,以安全事故致因层次为基础,将管理因素分为4部分,即人员因素、环境因素、材料因素和设备因素;进一步分析地铁坍塌事故发生的原因,构建地铁坍塌事故致因的鱼刺图;实证分析杭州地铁坍塌事故的致因,并构建杭州地铁坍塌事故致因的鱼刺图;在实证分析基础上,从地铁施工前与地铁施工时两时间段,针对人员因素、环境因素、材料因素和设备因素4方面管理因素,提出地铁坍塌事故的防范措施。以事故机理研究为基础,以管理因素研究为核心是研究地铁坍塌事故的必由之路,将对地铁工程的安全管理有一定的指导意义。  相似文献   
633.
基于数字图像处理技术的金相分析研究   总被引:2,自引:0,他引:2  
姜蓬  蒋勇  邱榕  廖光煊 《火灾科学》2009,18(3):163-167
采用和改进了人际交互式图像分割算法Live-wire,对电气火灾中的典型火烧金相图和一次短路金相图进行处理,结合数字形态学操作,精确提取了两类金相图中的典型胞状晶和柱状晶结构;分析和讨论了多种结构描述子对晶格分类的作用,结果表明,离心率和晶格标记方差两个描述子能有效区分两类晶格结构;采用聚类分析和Fisher判别法,实现了对两类金相图的自动分类.  相似文献   
634.
饮食业油烟道火灾的模糊事件树分析   总被引:3,自引:0,他引:3  
对饮食业油烟道火灾事故进行事件树分析时,历史数据的缺乏常常导致无法进行事件序列的定量计算.针对这一问题,利用专家对事故的模糊评判,引入模糊事件树进行定量计算研究.在模糊集理论的基础上,结合德尔菲法和判断矩阵法, 将模糊性语言转换为三角模糊数或梯形模糊数,应用模糊数截集以及模糊数清晰化方法,对后果事件发生概率进行计算.研究表明,饮食业油烟道火灾事故概率的模糊事件树分析是切实可行的,有助对饮食业油烟道火灾的认识、预防和扑救工作.  相似文献   
635.
Decision–support systems in the field of integrated water management could benefit considerably from social science knowledge, as many environmental changes are human-induced. Unfortunately the adequate incorporation of qualitative social science concepts in a quantitative modeling framework is not straightforward. The applicability of fuzzy set theory and fuzzy cognitive maps for the integration of qualitative scenarios in a decision–support system was examined for the urbanization of the coastal city of Ujung Pandang, Indonesia. The results indicate that both techniques are useful tools for the design of integrated models based on a combination of concepts from the natural and social sciences. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   
636.
炸药废水中TNR含量直接光度法测定的研究   总被引:2,自引:0,他引:2  
以三硝基间苯二酚 ( TNR)溶于水后 ,溶液呈现出明显的亮黄色 ,据此直接用光度法对炸药废水中 TNR的含量进行了测定 ,并论证了光度法的测试条件。同时以消解测氮法进行印证 ,结果表明方法具有可行性  相似文献   
637.
地下饮用水中痕量NO2-的催化动力学法测定   总被引:3,自引:0,他引:3  
报道了一种新的测定NO2-的高选择性和高灵敏度的催化光度分析法.基于H3PO4介质中,碘绿与溴酸钾的氧化还原反应受亚硝酸盐的催化使碘绿褪色.据此建立了测定NO2-的新方法.本方法检出限为0.29μg/L,该方法用于地下饮用水、环境标样的测定,相对标准偏差为1.05%~4.80%,加标回收率为95%~117%.  相似文献   
638.
The ongoing development of microbial source tracking has made it possible to identify contamination sources with varying accuracy, depending on the method used. The purpose of this study was to test the efficiency of the antibiotic resistance analysis (ARA) method under low resistance by tracking the fecal sources at Turkey Creek, Oklahoma exhibiting this condition. The resistance patterns of 772 water-isolates, tested with nine antibiotics, were analyzed by discriminant analysis (DA) utilizing a five-source library containing 2250 isolates. The library passed various representativeness tests; however, two of the pulled-sample tests suggested insufficient sampling. The resubstitution test of the library individual sources showed significant isolate misclassification with an average rate of correct classification (ARCC) of 58%. These misclassifications were explained by low antibiotic resistance (Wilcoxon test P < 0.0001). Seasonal DA of stream E. coli isolates for the pooled sources human/livestock/deer indicated that in fall, the human source dominated (P < 0.0001) at a rate of 56%, and that human and livestock respective contributions in winter (35 and 39%), spring (43 and 40%), and summer (37 and 35%) were similar. Deer scored lower (17–28%) than human and livestock at every season. The DA was revised using results from a misclassification analysis to provide a perspective of the effect caused by low antibiotic resistance and a more realistic determination of the fecal source rates at Turkey Creek. The revision increased livestock rates by 13–14% (0.04 ≤ P ≤ 0.06), and decreased human and deer by 6–7%. Negative misclassification into livestock was significant (0.04 ≤ P ≤ 0.06). Low antibiotic resistance showed the greatest effect in this category.  相似文献   
639.
Accurate knowledge of the quality and environmental impact of the highway runoff in Pear River Delta, South China is required to assess this important non-point pollution source. This paper presents the quality characterization and environmental impact assessment of rainfall runoff from highways in urban and rural area of Guangzhou, the largest city of Pear River Delta over 1 year’s investigation. Multiple regression and Pearson correlation analysis were used to determine influence of the rainfall characteristics on water quality and correlations among the constituents in highway runoff. The results and analysis indicates that the runoff water is nearly neutral with low biodegradability. Oil and grease (O&G), suspended solids (SS) and heavy metals are the dominant pollutants in contrast to the low level of nutrient constituents in runoff. Quality of highway runoff at rural site is better than that of at urban site for most constituents. Depth and antecedent dry period are the main rainfall factors influencing quality of highway runoff. The correlation patterns among constituents in highway runoff at urban site are consistent with their dominant phases in water. Strong correlations (r ≥ 0.80) are found among chemical oxygen demand (COD), total phosphorus, Cu and Zn as well as conductivity, nitrate nitrogen and total nitrogen. O&G, COD, SS and Pb in highway runoff at urban site substantially exceed their concentrations in receiving water of Pear River. The soil directly discharged by highway runoff at rural site has contaminated seriously by heavy metals in surface layer accompanying with pH conversion from original acidic to alkaline at present.  相似文献   
640.
Errors in environmental resource management over the years have created pollution problems in some areas which are difficult to handle, regardless of the development of knowledge and technologies. This is particularly true in the case of soil pollution. The negative effects of persistent pollutants have been observed for a long time. For instance, lead and cadmium remain in the soil for centuries, during which time they are absorbed by plants and simultaneously cause secondary air pollution. The authors made an attempt to describe and assess the possible options of dealing with the problem of contaminated land in Katowice District. Considering the necessity of a multilateral approach, a pairwise comparison technique has been chosen as the most suitable to show the complexity of the problem. The different variants of actions aimed at preventing the pollutants from getting into the food chain were analyzed against a set of criteria, consisting of the following issues: time, cost, effectiveness, social acceptance, feasibility. The relative importance of actions were judged by the team of experts using the Saaty method. Also, a two-perspective assessment (the two different stakeholders), which involves considering the perspective of an owner of a piece of contaminated land and an ecologist has been performed. The results of comparative, multicriteria and multi-perspective assessment indicate the following:- the best method for contaminated agricultural land management is willful and controlled cultivation,- other recommended actions are deep ploughing and phytoremediation,- there is not much acceptance for the other methods.  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