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   11647篇
  免费   916篇
  国内免费   1478篇
安全科学   1556篇
废物处理   160篇
环保管理   2161篇
综合类   6073篇
基础理论   1201篇
环境理论   19篇
污染及防治   664篇
评价与监测   1196篇
社会与环境   597篇
灾害及防治   414篇
  2024年   25篇
  2023年   182篇
  2022年   229篇
  2021年   322篇
  2020年   451篇
  2019年   334篇
  2018年   298篇
  2017年   416篇
  2016年   520篇
  2015年   522篇
  2014年   601篇
  2013年   763篇
  2012年   749篇
  2011年   996篇
  2010年   612篇
  2009年   771篇
  2008年   587篇
  2007年   741篇
  2006年   690篇
  2005年   491篇
  2004年   413篇
  2003年   465篇
  2002年   391篇
  2001年   369篇
  2000年   371篇
  1999年   304篇
  1998年   251篇
  1997年   247篇
  1996年   156篇
  1995年   152篇
  1994年   113篇
  1993年   121篇
  1992年   80篇
  1991年   57篇
  1990年   28篇
  1989年   28篇
  1988年   22篇
  1987年   19篇
  1986年   24篇
  1985年   20篇
  1984年   22篇
  1983年   7篇
  1982年   12篇
  1981年   16篇
  1980年   11篇
  1979年   8篇
  1978年   14篇
  1977年   10篇
  1975年   4篇
  1973年   2篇
排序方式: 共有10000条查询结果,搜索用时 78 毫秒
1.
Air pollution is one of the primary concerns of our society for its effect on human health and the environment. Among the policy measures that can be put in place to limit air pollutant emissions, end-of-pipe technologies and/or regulatory instruments may be implemented through legislative acts. Also, equally important are behavioural measures, requiring citizens’ active involvement. The success of any measure to limit pollutant emissions requires the acceptance by the citizens that, in turn, implies a correct perception of the main pollutant emission drivers. We present here the comparison between the public perception of air pollution sources and the real-world situation through a survey carried out in seven European countries and involving 16 101 respondents. Our study shows a dramatic underestimation of the contribution of the agri-food sector to air pollution. This result is common to all respondents in the seven countries examined and only to a small extent depends on gender, age and socio-economic status of the respondents.  相似文献   
2.
With the onset of social life, humans have considered waste disposal as essential, and they have been able to repel it through brick and clay channels. Checking sewage pipes for energy consumption and a longer lifetime than other sewage system components is important. Climate change and exploitation of industrial resources have made environmental impacts, which are important factors in decision making. The purpose of this study was to introduce the most suitable type of sewage pipe considering environmental protection. Therefore, we applied the environmental life cycle assessment (LCA) method, using Sima Pro 8.2.3 software for the one-kilometer length of concrete pipes (300 mm in diameter), Polyvinyl chloride (PVC), and polyethylene (PE) (315 mm in diameter). Also, the BEES method and sensitivity analysis were used to validate the results. The comparison between three types of municipal wastewater pipes indicated that PE pipes are a more environmentally friendly option than PVC, and concrete pipes in pipe recycling, reducing extraction from untapped resources, and inefficient extraction of resources. Electricity, diesel fuel, and sulfate resistance cement consumption for concrete production are the most pollution elements in the LCA of concrete pipes. Usage of PVC granular, sanitary landfill of PVC pipes, and using hydraulic drill in LCA of PVC pipes are the most elements of generating pollution. The usage of PE granules, PE pipes landfilling, hydraulic excavator, and electricity consumption in the LCA of the PE pipes are the greatest polluting parameters.  相似文献   
3.
Complex systems often experience a long period of incubation before accidents occur. Therefore, a proactive risk assessment is essential for process safety. The conventional job hazard analysis (JHA) method has been an effective tool to conduct a process risk assessment in the high-risk industrial field. However, the conventional JHA is inadequate for the proactive risk assessment since it is usually conducted during and before one specific operation process. Operations such as startup and maintenance are performed repeatedly on the lifecycle of a plant. Therefore, the risk reduction measures for the industrial process should include not only preventive actions obtained from the conventional JHA but also recovery ones. Resilience engineering (RE) has proven to be helpful for the recovery analysis of a complex system. The objective of this paper is to propose a proactive and comprehensive process risk assessment approach based on JHA and RE. The mechanism of applying RE to address operation process risk is illustrated. The integrated approach can provide guidelines to establish proactive risk reduction measures as well as maintain a low-risk level. Finally, a gas transmission startup process risk assessment case is presented to demonstrate its applicability.  相似文献   
4.
Abstract

Objective: With the overall goal to harmonize prospective effectiveness assessment of active safety systems, the specific objective of this study is to identify and evaluate sources of variation in virtual precrash simulations and to suggest topics for harmonization resulting in increased comparability and thus trustworthiness of virtual simulation-based prospective effectiveness assessment.

Methods: A round-robin assessment of the effectiveness of advanced driver assistance systems was performed using an array of state-of-the-art virtual simulation tools on a set of standard test cases. The results were analyzed to examine reasons for deviations in order to identify and assess aspects that need to be harmonized and standardized. Deviations between results calculated by independent engineering teams using their own tools should be minimized if the research question is precisely formulated regarding input data, models, and postprocessing steps.

Results: Two groups of sources of variations were identified; one group (mostly related to the implementation of the system under test) can be eliminated by using a more accurately formulated research question, whereas the other group highlights further harmonization needs because it addresses specific differences in simulation tool setups. Time-to-collision calculations, vehicle dynamics, especially braking behavior, and hit-point position specification were found to be the main sources of variation.

Conclusions: The study identified variations that can arise from the use of different simulation setups in assessment of the effectiveness of active safety systems. The research presented is a first of its kind and provides significant input to the overall goal of harmonization by identifying specific items for standardization. Future activities aim at further specification of methods for prospective assessments of the effectiveness of active safety, which will enhance comparability and trustworthiness in this kind of studies and thus contribute to increased traffic safety.  相似文献   
5.
● B[a]P, nicotine and phenanthrene molecules altered the secondary structure of Aβ42. ● β-content of the peptide was significantly enhanced in the presence of the PAHs. ● Nicotine made stable cluster with Aβ42 peptide via hydrogen bonds. ● Phenanthrene due to its small size, interfered with the Aβ42 monomer more strongly. Recent studies have correlated the chronic impact of ambient environmental pollutants like polycyclic aromatic hydrocarbons (PAHs) with the progression of neurodegenerative disorders, either by using statistical data from various cities, or via tracking biomarkers during in-vivo experiments. Among different neurodegenerative disorders, PAHs are known to cause increased risk for Alzheimer’s disease, related to the development of amyloid beta (Aβ) peptide oligomers. However, the complex molecular interactions between peptide monomers and organic pollutants remains obscured. In this work, we performed an atomistic molecular dynamics study via GROMACS to investigate the structure of Aβ42 peptide monomer in the presence of benzo[a]pyrene, nicotine, and phenanthrene. Interestingly the results revealed strong hydrophobic, and hydrogen-bond based interactions between Aβ peptides and these environmental pollutants that resulted in the formation of stable intermolecular clusters. The strong interactions affected the secondary structure of the Aβ42 peptide in the presence of the organic pollutants, with almost 50 % decrease in the α-helix and 2 %–10 % increase in the β-sheets of the peptide. Overall, the undergoing changes in the secondary structure of the peptide monomer in the presence of the pollutants under the study indicates an enhanced formation of Aβ peptide oligomers, and consequent progression of Alzheimer’s disease.  相似文献   
6.
为避免因腐蚀导致油气管道失效,针对因管道特性和腐蚀尺寸的不确定性使得管道剩余强度成为概率模型的特点,建立了腐蚀管道强度损失随机模型;借助可靠性理论,通过分析管道腐蚀进程的时变性特点,将管道系统由损伤积累和抗力衰减导致的剩余强度随机化;提出基于穿越率的腐蚀油气管道失效评定及安全寿命预测方法。研究结果表明:腐蚀速率和运行压力对管道失效概率及安全寿命影响显著,管道尺寸影响适中,而相关系数和拉伸强度影响较小;若腐蚀速率Va=0.2 mm/a,VL=10 mm/a或局部腐蚀缺陷半径达到管道壁厚的0.5倍时,建议作为重点风险段监测并检修。所建方法是对腐蚀油气管道运营监控和风险评估的有益补充。  相似文献   
7.
综述了工业废水毒性的化学评估方法、生物毒性评估方法、毒性鉴定评估(TIE)程序以及效应引导的毒物鉴别分析(EDA)中污染物提取、分离、毒性测试、致毒物质识别等技术。指出,工业废水毒害风险评估方法正逐渐向化学分析与生物毒性测试相结合的关键致毒物质鉴别方法转变,便捷、高通量是致毒物质鉴别技术的发展方向,质谱技术及替代定性监测技术的发展将提供更为准确、便捷的致毒物质鉴别方法,为工业废水潜在风险防控提供依据。  相似文献   
8.
依据2017年5、7、9月对三江平原19处沼泽湿地(参照湿地6处,受损湿地13处)的水生无脊椎动物采样结果,应用生物完整性理论和方法,构建水生无脊椎动物完整性指数,评价三江平原沼泽湿地健康状况。通过对27个候选指标的分布范围、判别能力和相关性分析,筛选出总分类单元数、扁卷螺科百分比、龙虱科百分比、刮食者百分比4个指标构成水生无脊椎动物完整性指数核心指标。采用比值法计算各指标参数值,将各参数值加和得到水生无脊椎动物完整性指数值。根据参照湿地水生无脊椎动物完整性指数值的25%分位数值确定评价标准,对小于25%分位数的值进行三等分,确定三江平原沼泽湿地健康评价标准:≥2.58,无干扰;1.72~2.58,轻度干扰;0.86~1.72,中度干扰;0~0.86,重度干扰。结果表明:所调查的三江平原沼泽湿地有78.95%受到不同程度的干扰(其中47.37%受到了中重度干扰),21.05%属于无干扰。  相似文献   
9.
交通干道沿线土壤重金属监测与评估综述   总被引:4,自引:0,他引:4  
公路运营所带来的铅、镉、锌等重金属污染物对人体健康安全存在着潜在和长期的影响。近年来,开展交通干道沿线重金属污染监测与评估工作已经成为环境监测工作的重要内容。从监测技术、评估方法、可能影响因素等几个方面对该领域的研究进展及成果进行了综述。采样段面的选取、点位的布设与样品的收集应该同时遵循全面性和代表性的原则。在同一交通干道内,均匀布置采样段面的同时可以尽量包含高车流量、中车流量与低车流量3种类型。考虑到重金属在横向距离上的分布规律,可以在0~100 m处设置密集采样点位,在100~300 m处设置适量采样点位。评估方法一般同时采用Kriging空间插值分析、污染指数分析、多元统计分析,生态风险评价与健康风险评价等多种分析方法。  相似文献   
10.
基于环境卫星CCD数据的黄海浒苔遥感监测   总被引:1,自引:1,他引:0  
2007年以来,黄海海域每年夏季都发生大面积浒苔绿藻潮,影响沿岸人民的生活、生产。考虑到其分布范围动则几千、上万平方公里,水面监测很难实施,尝试利用遥感技术对其分布和发展变化情况进行监测。基于中国自主产权的环境卫星(HJ1)数据,采用经典植被指数算法和人工辅助判读方法,对2013年黄海浒苔暴发全过程进行了连续遥感监测,分析了此次浒苔过程的分布和漂移路线。监测结果表明,浒苔绿藻潮首发于江苏盐城东部海域,由南向北逐渐漂移,面积逐渐扩大,结束于青岛东北部海域;该期间,浒苔最大覆盖面积达663.54平方公里。  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