全文获取类型
收费全文 | 14897篇 |
免费 | 1155篇 |
国内免费 | 1283篇 |
专业分类
安全科学 | 3279篇 |
废物处理 | 252篇 |
环保管理 | 4039篇 |
综合类 | 5405篇 |
基础理论 | 1385篇 |
环境理论 | 10篇 |
污染及防治 | 701篇 |
评价与监测 | 684篇 |
社会与环境 | 883篇 |
灾害及防治 | 697篇 |
出版年
2024年 | 21篇 |
2023年 | 197篇 |
2022年 | 319篇 |
2021年 | 427篇 |
2020年 | 503篇 |
2019年 | 395篇 |
2018年 | 324篇 |
2017年 | 479篇 |
2016年 | 598篇 |
2015年 | 540篇 |
2014年 | 624篇 |
2013年 | 850篇 |
2012年 | 979篇 |
2011年 | 1102篇 |
2010年 | 792篇 |
2009年 | 929篇 |
2008年 | 667篇 |
2007年 | 941篇 |
2006年 | 910篇 |
2005年 | 741篇 |
2004年 | 719篇 |
2003年 | 591篇 |
2002年 | 547篇 |
2001年 | 442篇 |
2000年 | 457篇 |
1999年 | 376篇 |
1998年 | 254篇 |
1997年 | 247篇 |
1996年 | 191篇 |
1995年 | 212篇 |
1994年 | 138篇 |
1993年 | 121篇 |
1992年 | 113篇 |
1991年 | 75篇 |
1990年 | 49篇 |
1989年 | 41篇 |
1988年 | 44篇 |
1987年 | 37篇 |
1986年 | 30篇 |
1985年 | 25篇 |
1984年 | 28篇 |
1983年 | 18篇 |
1982年 | 27篇 |
1981年 | 19篇 |
1980年 | 28篇 |
1979年 | 37篇 |
1978年 | 25篇 |
1973年 | 15篇 |
1972年 | 20篇 |
1971年 | 18篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
洪涝灾害条件下疏散交通生成预测方法 总被引:1,自引:0,他引:1
为有助于有关部门更准确预测洪涝灾害受灾民众的疏散量,结合非集计数据和集计数据的优点,提出分区集计数据的概念,设计了受灾区域分区方法,并通过意向偏好(SP)调查法对我国居民在洪涝条件下疏散交通需求数据进行调查。在此基础上,引入BP神经网络建立基于分区集计数据的疏散交通生成预测模型。利用调查数据进行实证分析发现,所设计方法取得了较好的预测效果,鲁棒性较好,平均相对预测误差仅为1.8%,其预测效果明显优于现有的非集计和整集计模型。 相似文献
2.
战略环境评价的工作程序 总被引:18,自引:1,他引:18
介绍了战略环境评价(法规、政策、计划和规划层次)工作程序的三个环节:评价方案的制定、评价实施和评价总结。并提出了战略环境评价指标体系制定的原则、战略环境评价的具体步骤及战略环境评价报告书的基本内容。 相似文献
3.
安徽月山地区是长江中下游地区的重要成岩-成矿区段。本文通过岩石学、岩石化学和同位素地球化学等方面的研究,探讨和阐明了月山地区闪长岩类的形成环境、物质来源、源区特征、岩浆形成与演化机理等。 相似文献
4.
5.
姚贵平 《安全.健康和环境》2002,2(2):17-19
对安庆分公司化肥厂合成氨装置 4年以来的运行及安全管理情况作了综述 . 对装置的重点 监督部位加强技术型管理 , 并实行了一系列行之有效的安全防范措施 , 使之达到了国内同类 型装置先进水平 . 相似文献
6.
The lessons of history indicate that mismanagement of natural resources and the environment often leads to potentially adverse consequences.The increasing interest in economic development,particularly in the developing countries of the world coupled with increasing population pressures and the globalization of economic activity is placing noticeable stresses on the ultimate sustainability of both human and environmental systems.Sustainable development is not a new concept.It has been an area of concern for different elements of society for some time.Yet efforts to understand the implications of sustainable development have not,until recently,been formalized.We have focused singularly on economic development and environmental quality as if they were mutually exclusive.This paper focuses on the concept of concurrency as both a conceptual framework and practicable method of understanding and implementing the ecology and economy of sustainability. 相似文献
7.
In this paper we deal with the problem of identifying environmental principles for the design and operation of supply chains. The operations that are included in supply chains are briefly described along with the approaches that are applied in order to improve their environmental performance. A background of environmental principles for achieving eco-efficiency and building of environmentally friendly organizational systems is presented and emphasis is put on the application of such principles “from cradle to grave”. Then, environmental principles applicable to particular objects of logistics networks planning are identified and commented upon. In addition, selective case studies from the literature, which show the applicability of the formulated principles and their relevance to practice, are discussed. The paper concludes with some remarks regarding the benefits for companies and societies, in general, that occur as a result of the application of the formulated principles. 相似文献
8.
9.
10.
Robert T. LackeyAuthor vitae 《Environmental Science & Policy》1998,1(4):329-335
Fisheries management is the practice of analyzing and selecting options to maintain or alter the structure, dynamics, and interaction of habitat, aquatic biota, and man to achieve human goals and objectives. The theory of fisheries management is: managers or decision makers attempt to maximize renewable `output' from an aquatic resource by choosing from among a set of decision options and applying a set of actions that generate an array of outputs. Outputs may be defined as a tangible catch, a fishing experience, an existence value, or anything else produced or supported by renewable aquatic resources. Overall output is always a mix of tangible and intangible elements. However defined, management goals and objectives are essential components of fisheries management or any other field of renewable natural resource management. Reaching consensus on management goals and objectives has never been a simple task. Beyond the broad and often conflicting goals of an agency, managers must decide who should set specific management objectives — agency personnel, the public, or a combination of the two. Historically, rhetoric aside, fisheries managers in North America nearly always have consulted with professionals in governmental roles to set management objectives. In a strongly pluralistic society, this often resulted in protracted political and legal conflict. Increasingly, there are calls for use of risk assessment to help solve such ecological policy and management problems commonly encountered in fisheries management. The basic concepts of ecological risk assessment may be simple, but the jargon and details are not. Risk assessment (and similar analytical tools) is a concept that has evoked strong reactions whenever it has been used. In spite of the difficulties of defining problems and setting management objectives for complex ecological policy questions, use of risk assessment to help solve ecological problems is widely supported. Ecological risk assessment will be most useful (and objective) in political deliberations when the policy debate revolves around largely technical concerns. To the extent that risk assessment forces policy debate and disagreement toward fundamental differences rather than superficial ones, it will be useful in decision making. 相似文献