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   1000篇
  免费   23篇
  国内免费   13篇
安全科学   53篇
废物处理   63篇
环保管理   202篇
综合类   95篇
基础理论   228篇
污染及防治   265篇
评价与监测   89篇
社会与环境   34篇
灾害及防治   7篇
  2023年   14篇
  2022年   10篇
  2021年   15篇
  2020年   17篇
  2019年   21篇
  2018年   21篇
  2017年   26篇
  2016年   22篇
  2015年   24篇
  2014年   33篇
  2013年   153篇
  2012年   51篇
  2011年   53篇
  2010年   30篇
  2009年   43篇
  2008年   48篇
  2007年   57篇
  2006年   40篇
  2005年   35篇
  2004年   31篇
  2003年   31篇
  2002年   30篇
  2001年   14篇
  2000年   13篇
  1999年   11篇
  1998年   15篇
  1997年   12篇
  1996年   9篇
  1995年   6篇
  1994年   15篇
  1993年   12篇
  1992年   8篇
  1991年   6篇
  1990年   6篇
  1989年   5篇
  1987年   9篇
  1986年   8篇
  1985年   8篇
  1984年   5篇
  1983年   4篇
  1982年   8篇
  1981年   6篇
  1980年   4篇
  1979年   5篇
  1978年   5篇
  1976年   4篇
  1958年   2篇
  1957年   3篇
  1956年   2篇
  1955年   3篇
排序方式: 共有1036条查询结果,搜索用时 468 毫秒
61.
62.
The Semi-Volatile Organic Sampling Train method was investigated to determine its reliability and to determine the bias and precision of the method when used to determine emissions from hazardous waste incinerators. Experiments showed that the matrix and sampling variables usually involved in sampling emissions from a hazardous waste incinerator had no significant effect on the recovery of 11 different organic compounds. Significant losses of the sampled compounds can occur during sample preparation. The degree of loss appears to be directly related to the compounds, vapor pressure. These losses can be corrected for by adding deuterated surrogates to the sample and analyzing the surrogates along with the native compounds.

The bias determination was based on dynamic spiking of the sampling train with five deuterated organic compounds selected from Appendix VIII of the Resource Conservation and Recovery Act regulations. The results show biases of from -1 ± 8 percent to -18 ± 27 percent for chlorinated and nonchlorinated compounds. Pyridine, a water-soluble compound, showed a larger bias of-29 ± 13 percent. Particular attention to the recovery of water soluble compounds is necessary to minimize bias in their determinations. Further work is needed to determine the reliability of laboratory-determined retention volumes that are used to determine sampling conditions.  相似文献   
63.
The precision and accuracy of the determination of particu-late sulfate and fluoride, and gas phase SO2 and HF are estimated from the results obtained from collocated replicate samples and from collocated comparison samples for high-and low-volume filter pack and annular diffusion denuder samplers. The results of replicate analysis of collocated samples and replicate analyses of a given sample for the determination of spherical aluminosilicate fly ash particles have also been compared. Each of these species is being used in the chemical mass balance source apportionment of sulfur oxides in the Grand Canyon region as part of Project MOHAVE, and the precision and accuracy analyses given in this paper provide input to that analysis. The precision of the various measurements reported here is ±1.8 nmol/m3 and ±2.5 nmol/m3 for the determination of SO2 and sulfate, respectively, with an annular denuder. The precision is ±0.5 nmol/m3 and ±2.0 nmol/m3 for the determination of the same species with a high-volume or low-volume filter pack. The precision for the determination of the sum of HF(g) and fine particulate fluoride is ±0.3 nmol/m3. The precision for the determination of aluminosilicate fly ash particles is ±100 particles/m3. At high concentrations of the various species, reproducibility of the various measurements is ±10% to ±14% of the measured concentration. The concentrations of sulfate determined using filter pack samplers are frequently higher than those determined using diffusion denuder sampling systems. The magnitude of the difference (e.g., 2-10 nmol sulfate/m3) is small, but important relative to the precision of the data and the concentrations of particulate sul-fate present (typically 5-20 nmol sulfate/m3). The concentrations of SO2(g) determined using a high-volume cascade impactor filter pack sampler are correspondingly lower than those obtained with diffusion denuder samplers. The concentrations of SOx (SO2(g) plus particulate sulfate) determined using the two samplers during Project MOHAVE at the Spirit Mountain, NV, and Hopi Point, AZ, sampling sites were in agreement. However, for samples collected at Painted Desert, AZ, and Meadview, AZ, the concentrations of SOx and SO2(g) determined with a high-volume cascade impactor filter pack sampler were frequently lower than those determined using a diffusion denuder sampling system. These two sites had very low ambient relative humidity, an average of 25%. Possible causes of observed differences in the SO2(g) and sulfate results obtained from different types of samplers are given.  相似文献   
64.
Plant uptake of toxins and their translocation to edible plant parts are important processes in the transfer of contaminants into the food chain. Atropine, a highly toxic muscarine receptor antagonist produced by Solanacea species, is found in all plant tissues and can enter the soil and hence be available for uptake by crops. The absorption of atropine and/or its transformation products from soil by wheat (Triticum aestivum var Kronjet) and its distribution to shoots was investigated by growing wheat in soil spiked with unlabeled or 14C-labeled atropine. Radioactivity attributable to 14C-atropine and its transformation products was measurable in plants sampled at 15 d after sowing (DAS) and thereafter until the end of experiment. The highest accumulation of 14C-atropine and/or its transformation products by plants was detected in leaves (between 73 and 90% of the total accumulated) with lower amounts in stems, roots, and seeds (approximately 14%, 9%, and 3%, respectively). 14C-Atropine and/or its transformation products were detected in soil leachate at 30, 60, and 90 DAS and were strongly adsorbed to soil, with 60% of the applied dose adsorbed at 30 DAS, plateauing at 70% from 60 DAS. Unlabeled atropine was detected in shoots 30 DAS at a concentration of 3.9 ± 0.1 μg kg?1 (mean ± SD). The observed bioconcentration factor was 2.3 ± 0.04. The results suggest a potential risk of atropine toxicity to consumers.  相似文献   
65.
Introduction and large-scale production of synthetic halogenated organic chemicals over the last fifty years has resulted in a group of contaminants that tend to persist in the environment and resist both biotic and abiotic degradation. The low solubility of these types of contaminants, along with their toxicity and tendency to accumulate in food chains, make them particularly relevant targets for remediation activities. Among the mechanisms that result in dehalogenation of some classes of organic contaminants are stimulation of metabolic sequences through introduction of electron donor and acceptor combinations; addition of nutrients to meet the needs of dehalogenating microorganisms; possible use of engineered microorganisms; and use of enzyme systems capable of catalyzing reductive dehalogenation. The current state of research and development in the area of reductive dehalogenation is discussed along with possible technological application of relevant processes and mechanisms to remediation of soil and groundwater contaminated with chlorinated organics. In addition, an overview of research needs is suggested, which might be of interest for development of in-situ systems to reduce the mass of halogenated organic contaminants in soil and groundwater.  相似文献   
66.
Since the term environmental ethics began to be used a generation ago, it has covered many different kinds of environmental notions, problems, ethical systems, and forms of behavior. A variety of cases are presented and examined under two terms,environmental ethics andecological morality, in an effort to illustrate different kinds of ethical objectives. In order to understand the connections between various strands of environmental ethics, personal and social values and subcultural norms of environmental ethics are examined under Christopher Stone's concept of moral pluralism. G. J. Warnock's notion of the general object of morality is proposed to integrate the variegated purposes of environmental ethics.  相似文献   
67.
ABSTRACT: Lawyers, engineers, and hydrologists are accustomed to thinking of water law as falling into one of two incompatible models: riparian rights (under which water is allocated by courts according to the relative reasonableness of the competing uses) and appropriative rights (under which water is allocated according to the temporal priority of the competing uses, largely by the action of the water users themselves but perfected by the issuance of an administrative permit). Usually unnoticed is the existence of a third approach, which I have dubbed “regulated riparianism.” Under regulated riparianism, water is allocated by water permits issued after an administrative determination of the reasonableness of the proposed use before the use is commenced. This system, now in place in about half of the states east of Kansas City (plus Hawaii), thus is fundamentally different from either the traditional ripanan rights that it replaces or the appropriative rights found in western states.  相似文献   
68.
A system for measuring environmental performance is important to the success of a company's environmental excellence program. In 1991, Niagara Mohawk Power Corporation (NMPC) unveiled a new corporate policy on protection of the environment. To measure and communicate progress in achieving the goals and objectives embodied in the new policy, an environmental performance index (EPI) was developed. In this article the author shows how the EPI utilizes a weight and rating scheme to reflect environmental performance in three categories: emissions/wastes, regulatory compliance, and environmental enhancements. Performance goals have been established for the period 1992–1995, and actual performance data has been compiled for 1992 and 1993. While the EPI is designed to measure changes in NMPC's environmental performance over time, it does not provide information on how the company's performance compares to that of other electric utilities. Accordingly, NMPC is developing an environmental benchmarking program with a group of Northeast electric utilities that will allow comparisons of environmental performance between utilities.  相似文献   
69.
The twin challenges of increased competition and environmental consciousness are causing companies in the utility industry to re-examine their methods for measuring environmental performance. A new paradigm is emerging which has already appeared in other industries—treating environmental quality as a potential source of profitability and competitive advantage. This article discusses how utilities and industrial companies can develop an environmental performance measurement framework, integrate it into their strategic and operating business practices, and use it for evaluation of alternative environmental strategies.  相似文献   
70.
This paper explores the implications of work schedule flexibility for family life. Based on data from the 1977 Quality of Employment Survey, it demonstrates that flexibility of work schedules moderates the effects of nonstandard work schedules on family life. That is, nonstandard work schedules tend to have a less negative association with the quality of family life when accompanied by a high level of schedule flexibility. The paper further demonstrates that this tendency of flexibility to act as a buffer against the negative effects of nonstandard work schedules on family life is more pronounced among working women than working men.  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