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   1001篇
  免费   23篇
  国内免费   12篇
安全科学   53篇
废物处理   63篇
环保管理   201篇
综合类   95篇
基础理论   228篇
污染及防治   266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   11篇
  2021年   15篇
  2020年   17篇
  2019年   21篇
  2018年   21篇
  2017年   26篇
  2016年   23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   14篇
  1997年   12篇
  1996年   9篇
  1995年   6篇
  1994年   14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 281 毫秒
31.
A panel discussion looking forward to the environment in the year 2000, was arranged by Lionel V. Baldwin, Program Chairman for APCA’s 67th Annual Meeting. To provide a lofty introduction of the subject he reached into outer space for a moderator—Captain Walter M. Schirra, one of the original astronaut team.  相似文献   
32.
Photocatalytic degradation of dissolved organic carbon (DOC) by utilizing Fe(III)-doped TiO2 at the visible radiation range is hereby reported. The photocatalyst was immobilized on sintered glass frits with the coating done by wet method, calcinated at 500 °C and then applied in a photodegradation reactor. The addition of a transition metal dopant, Fe(III), initiated the red shift which was confirmed by UV–Vis spectroscopy, and the photocatalyst was activated by visible radiation. X-ray diffraction patterns showed that Fe(III) doping had an effect on the crystallinity of the photocatalysts. Mixtures of DOC and associated coloured solutions were degraded in first-order kinetics, showing that the degradation process was not dependent on intermediates or other species in solution. A reactor with a catalyst coating area of 12.57 cm2 was able to degrade 0.623 mg of the dissolved material per minute. Exposure of the reactor to hostile acidic conditions and repeated use did not compromise its efficiency. It was observed that the reactor regenerates itself in the presence of visible light, and therefore, it can be re-used for more than 100 runs before the performance dropped to <95 %. The results obtained indicate that the photocatalyst reactor has a great potential of application for use in tandem with biosorbent cartridges to complement water purification methods for domestic consumption.  相似文献   
33.
Abstract

The primary objective of this investigation was to determine the feasibility of using acid activated clays to clarify menhaden stickwater effluent. Experiments, such as physical and chemical properties determinations, effect of changes in pH and temperature and coagulation, and coagulation followed by clay treatment were also performed to study the separation of solids in stickwater.

Analysis of the stickwater showed that it contained 4.5% crude protein, 1.4% crude fat, 6.5% total solids, 1.13% ash and 93.1% water. At a wavelength of 575 um, the sample absorbed all the light and the percent transmittance was zero. When diluted 1:100 the percent transmittance was 0.39 at the same wavelength. Measured at 25°C the sample had a viscosity of 9.0 centipoises.

The results showed that the precipitation of fat increased with increasing temperatures, while the reverse was true for protein. A pH of 4.0 gave the maximum clarification at all temperatures employed. The viscosity decreased at pH values above and below the original pH of the sample.

Among the four different acid activated clays used in this study (trade names Supact‐150, Impact‐150, Impact‐12 and Impact‐1OORR), Impact‐150 was the most effective in protein and fat precipitation, and the degree of separation of these components increased by treating stickwater with a coagulant (aluminum sulfate) prior to treatment with acid activated clay.  相似文献   
34.
This article is a series of representative case studies of Department of Defense hazardous waste minimization. Each Military Department and the Defense Logistics Agency describe actual accomplishments. Areas covered range from production line modification to product specification change. These efforts are part of a Department of Defense plan composed of individual programs executed independently by each military service and defense agency.

Part VII of the hazardous waste minimization series appears in two separate installments: the first installment, Part VII (A), dealt with Department of Defense waste minimization efforts in vehicle repair operations, explosives manufacturing, and abrasive blasting processes; Part VII (B) covers shipboard mercury wastes, industrial chemical control, solvent reclamation, and hazardous property sales efforts.  相似文献   
35.
The role of sulfur compounds in our environment has been the subject of much speculation during the past two decades. An evaluation of the effect of man-made contributions to the biogeochemical sulfur cycle requires a comprehensive examination of source magnitudes, atmospheric concentrations and removal processes. Many voids exist in our present knowledge of these parameters despite the contributions of numerous researchers. Adequate information is needed concerning the various forms of sulfur as well as other critical constituents which exist in our biosphere so that their interrelationship and role in the mechanisms of the sulfur cycle may be more fully understood.  相似文献   
36.
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   
37.
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   
38.
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   
39.
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   
40.
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   
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