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   438篇
  免费   2篇
  国内免费   5篇
安全科学   70篇
废物处理   22篇
环保管理   50篇
综合类   112篇
基础理论   113篇
环境理论   7篇
污染及防治   23篇
评价与监测   21篇
社会与环境   25篇
灾害及防治   2篇
  2023年   13篇
  2022年   6篇
  2021年   17篇
  2020年   21篇
  2019年   15篇
  2018年   17篇
  2017年   37篇
  2016年   35篇
  2015年   35篇
  2014年   51篇
  2013年   94篇
  2012年   3篇
  2011年   4篇
  2010年   5篇
  2009年   2篇
  2008年   1篇
  2007年   7篇
  2006年   6篇
  2005年   11篇
  2004年   12篇
  2003年   11篇
  2002年   9篇
  2001年   8篇
  2000年   2篇
  1999年   1篇
  1998年   2篇
  1996年   1篇
  1995年   8篇
  1992年   1篇
  1990年   1篇
  1989年   3篇
  1987年   3篇
  1986年   1篇
  1985年   1篇
  1983年   1篇
排序方式: 共有445条查询结果,搜索用时 15 毫秒
421.
Sanjad–Sakati syndrome (SSS) is an autosomal recessive disorder characterized by congenital hypoparathyroidism, growth and mental retardation. In Saudi Arabia, the disease is caused by a deletion of 12 bp (155-166nt) in the tubulin-specific chaperone E gene. In a family with two affected siblings with SSS, preimplantation genetic diagnosis (PGD) was performed. Fluorescent PCR (F-PCR) was utilized to check the heterozygosity and the homozygosity status of the parents and the affected children, respectively. F-PCR was then optimized for single-cell analysis by using peripheral blood lymphocytes. The patient underwent a cycle with intra-cytoplasmic sperm injection. A total of 11 embryos were obtained and biopsied. There were five heterozygous, three homozygous affected and three normal embryos. One heterozygous and one normal embryo were transferred because of their very good quality (morula). A singleton pregnancy was obtained, and amniosynthesis confirmed the presence of the heterozygous fetus. These results show for the first time, the feasibility of PGD for SSS. Copyright © 2004 John Wiley & Sons, Ltd.  相似文献   
422.
Aluminum–lithium (Al–Li) alloys are very attractive for potential aerospace applications due to their lower density, higher specific strength and rigidity, better corrosion and fatigue crack growth resistance properties, compared to conventional aluminum alloys. Laser beam welding (LBW), being an advanced joining method, has already been approved for applications involving aluminum alloys. However, there are still a number of problems and issues to be answered and solved in LBW of Al–Li alloys. In this review, the properties of Al–Li alloys and the characteristics of LBW are introduced, the formation and prevention of the main weld defects such as porosity and hot cracking are discussed, and then the weld microstructure and the joint mechanical properties are described in highlight. At the end, an outlook on future trends is presented.  相似文献   
423.
A thermo-mechanical model has been developed for modeling of hot extrusion processes. Accordingly, an admissible velocity field was first proposed by means of stream function method and then, extrusion pressure as well as temperature variations within the metal and the die were predicted employing a combined upper bound and Petrov–Galerkin finite element analysis. In order to evaluate the model predictions, hot extrusion of AA6061-10%SiCp was considered under both isothermal and non-isothermal conditions and the predicted force–displacement diagrams under various extrusion conditions were compared with the experimental ones and reasonable consistency was found between the two sets of results.  相似文献   
424.
利用ICP-MS半定量分析对应急监测水样进行全谱图扫描,初步判断质量范围6~260的所有重金属离子及其同位素的浓度,快速找到主要重金属污染物。该方法简单、快捷,不受标准物质使用限制,预处理方法简单,测定值与标准值的相对误差结果小于±30%。通过及时更新半定量响应因子曲线,可使半定量结果更为准确,为进一步准确定量提供可靠浓度范围。对应急监测过程中的复杂基体水样、未知水样的分析具有实际意义。通过分析企业的重金属排放浓度,可用于判定企业偷排漏排现象。  相似文献   
425.
The paper proposes an imprecise Fault Tree Analysis in order to characterize systems affected by the lack of reliability data. Differently from other research works, the paper introduces a classification of basic events into two categories, namely Initiators and Enablers. Actually, in real industrial systems some events refer to component failures or process parameter deviations from normal operating conditions (Initiators), whereas others refer to the functioning of safety barriers to be activated on demand (Enablers). As a consequence, the output parameter of interest is not the classical probability of occurrence of the top event, but its Rate of OCcurrence (ROCOF) over a stated period of time. In order to characterize the basic events, interval-valued information supplied by experts are properly aggregated and propagated to the top. To this purpose, the Dempster–Shafer Theory of evidence is proposed as a more appropriate mathematical framework than the classical probabilistic one. The proposed methodology, applied to a real industrial scenario, can be considered a helpful tool to support risk managers working in industrial plants.  相似文献   
426.
This paper presents results of an experimental investigation on fast flame propagation and the deflagration-to-detonation transition (DDT) and following detonation propagation in a semi-confined flat layer filled with stratified hydrogen–air mixtures. The experiments were performed in a transparent, rectangular channel open from below. The combustion channel has a width of 0.3 m and a length of 2.5 m. The effective layer thickness in the channel was varied by using different linear hydrogen concentration gradients. The method to create quasi-linear hydrogen concentration gradients that differ in the range and slope is also presented. The ignited mixtures were accelerated quickly to sonic flame speed in the first obstructed part of the channel. The interaction of the fast flame propagation with different obstacle set-ups was studied in the second part of the channel. The experimental results show an initiation of DDT by one additional metal grid in the obstructed semi-confined flat layer. Detonation propagation and failed detonation propagation were observed in obstructed and unobstructed parts of the channel.  相似文献   
427.
This article addresses methodological issues of the human reliability analysis (HRA) in the context of probabilistic safety studies. Several conventional HRA techniques, more often used for the evaluation of the human error probabilities (HEPs), have been classified. A taxonomy of human actions, failure events, and related factors is outlined in order to distinguish action phases, human behavior types and incorrect outputs (errors of omission or commission), error types (slips, lapses, and mistakes), and performance-shaping factors (PSFs) influencing the human performance. A tree is proposed to facilitate the selection of a specific method for the evaluation of human reliability with regard to attributes of the situation analyzed. A software system based on the expert system technology to facilitate and document PSA and HRA is outlined. At the end of the article some research challenges in the domain are discussed.  相似文献   
428.
The aim of the present study was to estimate spillover effects between the work and the family sphere in a sample of nurses (N = 2058). Hierarchical regression analyses investigated whether shift work schedules were associated with negative or positive spillover, both from family to work and vice versa, controlling for demographic factors, job demands and decision latitude. With daytime work as a reference group, all types of shift work (day and evening shift, night shift only and rotating 3 shift) were associated with higher negative work-to-family spillover. Night work was associated with significantly less negative family-to-work spillover. None of the different shift work schedules were related to any type of positive spillover. The results indicate that working outside of daytime hours is less compatible with workers’ family lives, compared to working ordinary day shifts. On the other hand, working night shifts only was associated with reduced negative family-to-work spillover.  相似文献   
429.
Aron Ralston and Christopher McCandless, two outdoor adventurers, have captured the hearts of many American environmentalists. Each has attained the status of cultural icons and inspired books and films to recount their tales. While entertainment media have romanticized both individuals, news media are not as easy on one—McCandless is vilified while Ralston is valorized. When reporting these stories, news media outlets attempted to retell each story in a way that conforms to the dominant American ideology of wilderness, where “progress” is marked by control over nature—control that both Ralston and McCandless clearly unsettled. In addition, both committed many of the same errors in being underprepared. Despite these similarities, why are they each presented so differently in the news media? This paper offers a rhetorical analysis of newspaper articles on each story, where the phenomenon of scapegoating alienates McCandless, and the phenomenon of mortification purifies Ralston, restabilizing this American environmental ideology in both stories. In conclusion, I argue that the essential difference between these two stories is that they present two opposing ideals of a human–nature relationship, with Ralston's ideology including a space for technology and industrial knowledge, and thus construed as more appropriate than McCandless' ideology.  相似文献   
430.
The contribution contained in this paper focuses on providing a possible framework or approach in respect of how manufacturing companies can economically introduce environmentally friendly practices to their production operations, whilst at the same time encouraging organisational and operational learning with the aim of eventual evolution of the firm into an eco-efficient concern. A key premise associated with the approach advocated is economical organisational and operational learning over time, thus providing a sequential movement of the company through various stages of cultural change and technological capability to eventually achieve eco-efficiency in its production activities. At each stage in the process, it is suggested that a balance must be maintained between on the one hand, a reduction in operational economics consistent with on the other hand, an improvement in the environmental sustainability of company activities. To that end, some previously suggested monitoring metrics are examined in the text for their efficacy and economic rapport via hypothetical examples of how they might be applied in practice to monitor movement towards industrial–environmental sustainability.  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