全文获取类型
收费全文 | 10472篇 |
免费 | 1154篇 |
国内免费 | 2545篇 |
专业分类
安全科学 | 1438篇 |
废物处理 | 165篇 |
环保管理 | 1788篇 |
综合类 | 6924篇 |
基础理论 | 1367篇 |
环境理论 | 7篇 |
污染及防治 | 913篇 |
评价与监测 | 1107篇 |
社会与环境 | 396篇 |
灾害及防治 | 66篇 |
出版年
2024年 | 169篇 |
2023年 | 299篇 |
2022年 | 426篇 |
2021年 | 494篇 |
2020年 | 497篇 |
2019年 | 452篇 |
2018年 | 340篇 |
2017年 | 454篇 |
2016年 | 472篇 |
2015年 | 523篇 |
2014年 | 521篇 |
2013年 | 697篇 |
2012年 | 711篇 |
2011年 | 787篇 |
2010年 | 621篇 |
2009年 | 631篇 |
2008年 | 491篇 |
2007年 | 704篇 |
2006年 | 714篇 |
2005年 | 530篇 |
2004年 | 465篇 |
2003年 | 504篇 |
2002年 | 432篇 |
2001年 | 392篇 |
2000年 | 359篇 |
1999年 | 262篇 |
1998年 | 202篇 |
1997年 | 176篇 |
1996年 | 156篇 |
1995年 | 113篇 |
1994年 | 116篇 |
1993年 | 82篇 |
1992年 | 70篇 |
1991年 | 57篇 |
1990年 | 42篇 |
1989年 | 18篇 |
1988年 | 13篇 |
1987年 | 28篇 |
1986年 | 15篇 |
1985年 | 11篇 |
1984年 | 6篇 |
1982年 | 16篇 |
1981年 | 17篇 |
1980年 | 13篇 |
1979年 | 10篇 |
1978年 | 16篇 |
1977年 | 5篇 |
1973年 | 8篇 |
1972年 | 8篇 |
1971年 | 11篇 |
排序方式: 共有10000条查询结果,搜索用时 9 毫秒
801.
William Whipple Joseph V. Hunter 《Journal of the American Water Resources Association》1981,17(4):678-683
: The modeling of dissolved oxygen in streams is a widely used technique, upon which a great deal of money has been spent. This paper concludes that the standard methods of DO modeling by computer are unnecessarily complex, and that for some purposes, they can be replaced without loss of accuracy by desk top BOD models. Taking as an example, a set of data used in DO modeling, it is shown (a) that the data are grossly inconsistent, (b) that simultaneous gathering of data introduces errors in streams of long travel time, (c) that much more data as to pollutant concentrations should have been obtained, and (d) that 24-hour DO data could have been dispensed with. 相似文献
802.
Michael Donovan Charles A. Job William C. Sonzogni 《Journal of the American Water Resources Association》1981,17(1):23-28
ABSTRACT: The Illinois v. Milwaukee Federal District Court decision is the most far reaching application yet of the federal common law of nuisance to interstate water pollution conflicts. Although a Federal Appelate Court recently rescinded part of the district court decision, Milwaukee must still upgrade its metropolitan sewage system to a level beyond that required by federal and state regulations. The improvements must be completed with or without federal aid. The case points out the apparent inability of the Clean Water Act, the most comprehensive federal legislation affecting the nation's water quality, to deal with certain interstate water quality conflicts. The Milwaukee decision could set a precedent for similar settlements elsewhere which may in turn affect the U.S. Environmental Protection Agency's water quality clean up program. A more integrated, ecosystem conscious approach to management of shared water resources (e.g., the Great Lakes) would help reduce the need for court decisions like Illinois v. Milwaukee. 相似文献
803.
Harold E. Marshall Rosalie T. Ruegg 《Journal of the American Water Resources Association》1976,12(5):903-917
ABSTRACT: The Environmental Protection Agency administers a construction grant program to encourage abatement of wastewater pollution by sharing with municipalities the costs of wastewater treatment facilities. The enabling legislation (P.L. 92–500) specifies that EPA's cost share will be 75% of construction costs. It further requires municipalities to collect user fees from industrial users of the facilities to repay that part of the federal grant allocable to the treatment of industrial wastewater. The municipality must return half of the user fees collected to the U.S. Treasury; the municipality is allowed to retain the remaining half. Retention by municipalities of these user fees lowers their effective cost shares and results in the following consequences: (1) a bias for municipalities to select certain kinds of abatement techniques regardless of whether or not they are the least-cost techniques from the national perspective; (2) a bias for municipalities to select larger-than-optimal scales of abatement facilities; (3) a hidden federal subsidy to industry; and (4) grants that favor industrial communities. This article examines the legislative and regulatory requirements for user charges, derives the algebraic expressions for calculating the real federal, municipal, and industrial cost shares with user fees; computes municipal cost shares for selected values of the determinant factors; evaluates efficiency and other consequences of current user fee arrangements; and concludes that the efficiency distortions brought about by the impacts of user fees on cost sharing could be eliminated by requiring that all user fees collected from industry against the federal cost share be returned to the U.S. Treasury. 相似文献
804.
J. L. Hanisch B. R. Hart W. S. Turetsky H. T. Garabedian G. H. Pain 《Environmental management》1978,2(2):127-133
The body of information presented in this paper is directed to air pollution engineers who are concerned with the effect of indirect sources on ambient concentrations of carbon monoxide (CO). Data taken under controlled conditions are used to empirically derive and calibrate a model for predicting CO concentrations in the vicinity of roadway intersections and other points of possible vehicular congestion. Since the predicted free flow CO contribution of vehicles traveling at normal road speeds is relatively low, it is concluded that idling vehicles at points of congestion are the major cause of CO violations, and that state and federal programs should place more emphasis on relieving congestion and reducing idling emission rates in new vehicles. 相似文献
805.
Relative to manufacturing, service activities are often considered by planners and officials to generate considerably less environmental pollution. This hypothesis is tested by means of an examination of the economic linkages of both manufacturing and service activities and of the resulting direct and indirect emissions of five air pollutants per dollar of output in the California statewide air basin and in four regional basins within the state. Overall acceptance or rejection of the hypothesis depends in part on the particular pollutant and air basin considered but, most importantly, on the judgement as to what activities are to be considered as service activities.This paper is based on research sponsored by the California Air Resources Board under Agreement A7-143-30. 相似文献
806.
Michael N. Beaulac Kenneth H. Reckhow 《Journal of the American Water Resources Association》1982,18(6):1013-1024
ABSTRACT: Lake and watershed management strategies and recent environmental legislation dictate that nonpoht nutrient sources associated with storm water runoff must be assessed. Accordingly, a nutrient flu assessment for phosphorus and nitrogen is conducted through an extensive literature review of nutrient export studies. These studies are reevaluated. The nutrient export coefficients are screened according to sampling design criteria and compiled according to land use. The ecological mechanisms within each land use influencing the magnitude of nutrient flux are also discussed 相似文献
807.
对环太湖丘陵地区农田氮素随地表径流的输出特征进行了研究,结果表明,地表径流中TN浓度随径流量而变化,浓度峰值出现时间滞后于径流量峰值;径流发生前期,NH3 N和NO-3 N浓度水平相当,后期NO-3 N浓度缓慢抬升,而NH3 N含量缓慢下降;NO-2 N浓度相对较低,随时间快速下降;对于TN和NO-3 N而言,溶解态含量高于悬浮态,而溶解态和悬浮态NH3 N的浓度相当;无机氮平均浓度高于有机氮,有机氮尤其是悬浮态有机氮浓度表现出随径流量而变化的特点。 相似文献
808.
微生物絮凝剂的研究与应用进展 总被引:50,自引:0,他引:50
微生物絮凝剂是具有广阔应用前景的一种天然高分子絮凝剂,因而引起科学界的高度重视.自70年代以来,美国和日本等十多个国家已对其进行了详细的研究.本文综述了微生物絮凝剂的研究与应用进展,包括合成絮凝剂的微生物种类、微生物絮凝剂的化学本质、遗传基础和微观结构、微生物絮凝剂的絮凝机理和絮凝能力及其影响因素,微生物絮凝剂的合成条件和提取方法等方面.文中还给出了微生物絮凝剂在污染治理等领域实际应用的若干事例. 相似文献
809.
面对经济高速发展带来的工业污染形势,从工业污染问题的结构性问题突出、环境风险隐患大、污染物排放总量大等三大现状入手,对工业污染问题产生的经济和社会原因进行了分析,经济原因主要是追求利益最大化,环保资金投入不足和工业生产的外部不经济性,社会原因主要是环境社会责任感不足和监督体制机制不完善,提出了积极发展循环经济,充分借助市场经济之手和完善行政管控制度的对策,得出了迫切需要加快工业污染治理的结论。 相似文献
810.
Microflora of Soils Polluted with Petroleum Products 总被引:1,自引:0,他引:1