全文获取类型
收费全文 | 764篇 |
免费 | 102篇 |
国内免费 | 74篇 |
专业分类
安全科学 | 248篇 |
废物处理 | 8篇 |
环保管理 | 234篇 |
综合类 | 227篇 |
基础理论 | 70篇 |
环境理论 | 5篇 |
污染及防治 | 31篇 |
评价与监测 | 26篇 |
社会与环境 | 46篇 |
灾害及防治 | 45篇 |
出版年
2024年 | 1篇 |
2023年 | 14篇 |
2022年 | 20篇 |
2021年 | 28篇 |
2020年 | 22篇 |
2019年 | 32篇 |
2018年 | 29篇 |
2017年 | 49篇 |
2016年 | 47篇 |
2015年 | 41篇 |
2014年 | 43篇 |
2013年 | 40篇 |
2012年 | 49篇 |
2011年 | 69篇 |
2010年 | 40篇 |
2009年 | 62篇 |
2008年 | 34篇 |
2007年 | 54篇 |
2006年 | 44篇 |
2005年 | 25篇 |
2004年 | 29篇 |
2003年 | 17篇 |
2002年 | 18篇 |
2001年 | 13篇 |
2000年 | 15篇 |
1999年 | 17篇 |
1998年 | 11篇 |
1997年 | 12篇 |
1996年 | 6篇 |
1995年 | 10篇 |
1994年 | 9篇 |
1993年 | 8篇 |
1992年 | 6篇 |
1991年 | 2篇 |
1990年 | 1篇 |
1989年 | 4篇 |
1988年 | 3篇 |
1987年 | 1篇 |
1985年 | 1篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1982年 | 3篇 |
1981年 | 2篇 |
1980年 | 2篇 |
1977年 | 2篇 |
1974年 | 1篇 |
1973年 | 1篇 |
1972年 | 1篇 |
排序方式: 共有940条查询结果,搜索用时 15 毫秒
471.
This paper takes a close look at communication, process, power and institutional arrangements in the context of strategic planning. It introduces an eight step process for structuring strategic thinking and acting and develops the concept of “arenas” as a very influential — yet often very subtle — exercise of power over the course of a strategic planning process. 相似文献
472.
Ecological limitations and appropriation of ecosystem support by shrimp farming in Colombia 总被引:4,自引:0,他引:4
Shrimp farming in mangrove areas has grown dramatically in Asia and Latin America over the past decade. As a result, demand
for resources required for farming, such as feed, seed, and clean water, has increased substantially. This study focuses on
semiintensive shrimp culture as practiced on the Caribbean coast of Colombia. We estimated the spatial ecosystem support that
is required to produce the food inputs, nursery areas, and clean water to the shrimp farms, as well as to process wastes.
We also made an estimate of the natural and human-made resources necessary to run a typical semiintensive shrimp farm. The
results show that a semiintensive shrimp farm needs a spatial ecosystem support—the ecological footprint—that is 35–190 times
larger than the surface area of the farm. A typical such shrimp farm appropriates about 295 J of ecological work for each
joule of edible shrimp protein produced. The corresponding figure for industrial energy is 40:1. More than 80% of the ecological
primary production required to feed the shrimps is derived from external ecosystems. In 1990 an area of 874–2300 km2 of mangrove was required to supply shrimp postlarvae to the farms in Colombia, corresponding to a total area equivalent to
about 20–50% of the country’s total mangrove area. The results were compared with similar estimates for other food production
systems, particularly aquacultural ones. The comparison indicates that shrimp farming ranks as one of the most resource-intensive
food production systems, characterizing it as an ecologically unsustainable throughput system. Based on the results, we discuss
local, national, and regional appropriation of ecological support by the semiintensive shrimp farms. Suggestions are made
for how shrimp farming could be transformed into a food production system that is less environmentally degrading and less
dependent on external support areas. 相似文献
473.
风暴潮期间海塘工程的安全是防汛工作的重要问题。本文对海塘工程安全的影响因素进行了分析,提出了海塘工程安全预警的思路,并将决策支持系统这一新技术引入防台抗潮的决策工作中,以提高决策人的决策能力。 相似文献
474.
基于Matlab优化工具箱的煤巷顶板锚杆支护结构可靠性分析 总被引:2,自引:2,他引:2
针对煤巷围岩力学参数中有许多为随机变量的特征,根据围岩稳定性极限状态方程,应用工程结构可靠性理论,分析煤巷顶板锚杆支护结构的可靠性,建立基于Matlab优化工具箱的可靠度计算模型。该法编程简单,计算速度快,精度高,程序通用性强,是一种计算煤巷锚杆支护结构可靠度的有效方法,并且分析该法计算结构可靠度的适用条件,建立了巷道顶板支护参数与可靠度的关系曲线,为煤巷锚杆支护参数设计和优化提供了科学依据。 相似文献
475.
Developing the ethical matrix as a decision support framework: GM fish as a case study 总被引:2,自引:0,他引:2
Matthias Kaiser Kate Millar Erik Thorstensen Sandy Tomkins 《Journal of Agricultural and Environmental Ethics》2007,20(1):65-80
The Ethical Matrix was developed to help decision-makers explore the ethical issues raised by agri-food biotechnologies. Over
the decade since its inception the Ethical Matrix has been used by a number of organizations and the philosophical basis of
the framework has been discussed and analyzed extensively. The role of tools such as the Ethical Matrix in public policy decision-making
has received increasing attention. In order to further develop the methodological aspects of the Ethical Matrix method, work
was carried out to study the potential role of the Ethical Matrix as a decision support framework. When considering which
frameworks to apply when analyzing the ethical dimensions of the application of agri-food biotechnologies, it is important
to clarify the substantive nature of any prospective framework. In order to further investigate this issue, reflections on
the neologism “ethical soundness” of an ethical framework are presented here. This concept is introduced in order to provide
more structured evaluations of a range of ethical tools, including ethical frameworks such as the Ethical Matrix. As well
as examining the philosophical dimensions of the method, theoretical analysis and literature studies were combined with stakeholder
engagement exercises and consultations in order to review the Ethical Matrix from a user perspective. This work resulted in
the development of an Ethical Matrix Manual, which is intended to act as a guide for potential user groups. 相似文献
476.
M. Kashif Gill Mariush W. Kemblowski Mac McKee 《Journal of the American Water Resources Association》2007,43(4):1004-1015
Abstract: A hybrid data assimilation (DA) methodology that combines two state‐of‐the‐art techniques, support vector machines (SVMs) and ensemble Kalman filter (EnKF), is applied for soil moisture DA in this work. The SVM methodology provides a statistically sound and robust approach to solving the inverse problem, and thus to building statistical models. EnKF is an extension of the Kalman Filter (KF), a well‐known tool in prediction updating. In the present research, ground measurements were used to build a SVM‐type soil moisture predictor. Subsequent observations and their statistics were assimilated to update predictions from the SVM model by coupling it with EnKF. In this way, both model predictions and ground data, as well as their statistics, are fused thus minimizing the prediction error and making the predictions and observations statistically consistent. The results are shown for two approaches; one in which update is done at every time step and the other which assumes that data is only available at alternate time steps (in window of 10 time steps) and hence update is performed at those occasions. The SVM‐EnKF coupling is shown to improve soil moisture forecasts in an example using data from the Soil Climate Analysis Network site at Ames, Iowa. 相似文献
477.
G.L.L. Reniers B.J.M. Ale W. Dullaert B. Foubert 《Journal of Loss Prevention in the Process Industries》2006,19(6):604-620
Solid major accident prevention management is characterized by efficient and effective risk assessments. As a means of addressing the efficiency aspect, decision support analysis software is becoming increasingly available. This paper discusses the results of a survey of decision support tools for investigating (internal and external) major hazards in the chemical industry. The most significant features, such as the usability and the functionality of the toolkits are discussed. Toolkit characteristics are analyzed in the light of the different major risk decision process stages. Consequently, valuable supportive information for company decision makers purchasing such software is given. Furthermore, conclusions are drawn and recommendations are formulated for establishing priorities for future risk toolkits developments. 相似文献
478.
Eccleston CH 《Environmental management》2000,26(4):457-464
decision-based scoping —provides an effective methodology for improving the EIS scoping process. Decision-based scoping, in conjunction with a new
tool, the decision-identification tree (DIT), places emphasis on first identifying the potential decisions that may eventually need to be made. The DIT provides
a methodology for mapping alternative courses of action as a function of fundamental decision points. Once these decision
points have been correctly identified, the range of actions, alternatives, and impacts can be more accurately assessed; this
approach can improve the effectiveness of EIS planning, while reducing the risk of future disconnects between the EIS analysis
and reaching a final decision. This approach also has applications in other planning disciplines beyond that of the EIS. 相似文献
479.
/ A predictive model for assessing stand condition as a function of suitability for achieving specified management objectives was originally developed using a data set for only 28 stands. In this study, we evaluate the model using an operational-sized data set composed of currently collected stand inventory data for 238 stands in the Snowy Range of the Medicine Bow National Forest in southern Wyoming. We compared its predictions of old growth suitability to results of a separate special old growth survey. Stands were characterized as profiles of variables derived from stand inventory data, and plotted as points in two-dimensional space where similarity between stands was reflected by the distance between their points. Results suggest the model is useful for classifying stand condition using relatively large sets of data currently collected during routine stand inventories. 相似文献
480.
武器装备远程维修决策支援系统设计与开发 总被引:1,自引:1,他引:0
介绍了在网络技术环境下武器装备远程维修决策支援系统的设计与开发方案,简述了系统中的数据处理流程:数据源层、数据采集、数据仓库层、远程传输层、决策分析层、应用层等,介绍了系统的功能模块以及功能模块的功能、应用对象等。 相似文献