全文获取类型
收费全文 | 1500篇 |
免费 | 157篇 |
国内免费 | 212篇 |
专业分类
安全科学 | 155篇 |
废物处理 | 24篇 |
环保管理 | 313篇 |
综合类 | 785篇 |
基础理论 | 239篇 |
污染及防治 | 55篇 |
评价与监测 | 99篇 |
社会与环境 | 165篇 |
灾害及防治 | 34篇 |
出版年
2024年 | 6篇 |
2023年 | 19篇 |
2022年 | 48篇 |
2021年 | 50篇 |
2020年 | 44篇 |
2019年 | 45篇 |
2018年 | 45篇 |
2017年 | 64篇 |
2016年 | 65篇 |
2015年 | 71篇 |
2014年 | 57篇 |
2013年 | 92篇 |
2012年 | 107篇 |
2011年 | 111篇 |
2010年 | 112篇 |
2009年 | 89篇 |
2008年 | 75篇 |
2007年 | 136篇 |
2006年 | 109篇 |
2005年 | 70篇 |
2004年 | 53篇 |
2003年 | 57篇 |
2002年 | 47篇 |
2001年 | 35篇 |
2000年 | 50篇 |
1999年 | 35篇 |
1998年 | 26篇 |
1997年 | 25篇 |
1996年 | 24篇 |
1995年 | 18篇 |
1994年 | 12篇 |
1993年 | 16篇 |
1992年 | 17篇 |
1991年 | 7篇 |
1990年 | 5篇 |
1989年 | 2篇 |
1988年 | 2篇 |
1987年 | 3篇 |
1985年 | 2篇 |
1984年 | 1篇 |
1983年 | 5篇 |
1982年 | 1篇 |
1981年 | 1篇 |
1980年 | 3篇 |
1978年 | 1篇 |
1977年 | 2篇 |
1974年 | 1篇 |
1973年 | 1篇 |
1972年 | 1篇 |
1970年 | 1篇 |
排序方式: 共有1869条查询结果,搜索用时 796 毫秒
151.
Gideon Fishelson 《Journal of the American Water Resources Association》1973,9(4):801-815
The study contains the methodology of finding the optimal time to start the operation of a desalting plant or any other non conventional source of water for agricultural use in Israel. The essence of the methodology is the moving equilibrium price and quantity of agricultural products. The market of agricultural products is represented by a single demand curve and a supply curve which is derived from the agricultural sector production function. Both the demand for and the supply of agricultural products functions are shifting over time. The marginal value product of water is the critical value that determines the optimal time of a desalting plant. The study is static in the sense that dynamic aspects per se are not dealt with-e.g. learning by doing of building and operating desalting plants. The empirical results although used for illustrative purposes can be used as reference points for other detailed and more ‘exact’ studies on water desalination. 相似文献
152.
风险投资已经被各国公认为中小企业尤其是高科技企业成长的"推进器"。为了深入理解风险投资的本质,从风险投资的行为和基本特征入手,通过对价值理论的回顾和企业价值表述方式的描述,揭示了风险投资作为发现价值型投资的本质,即通过发现投资对象的潜在价值并通过不断的增值服务使潜在的价值逐步显化,从而得到大多数投资者认可后实施股权转让获得丰厚回报的投资本质。 相似文献
153.
An active ethically conscious consumer has been acclaimed as the new hero and hope for an ethically improved capitalism. Through
consumers’ “voting” at the checkout, corporations are supposed to be held accountable for their conduct. In the literature
on political consumerism, this has mainly been approached as political participation and governance. In this article, we do
a critical review of this literature. We do so by questioning the existence of what we call a “generic active consumer model.”
At the core of this position, there is a belief that the active consumer is a universal entity, available across nations and
time. Instead we call for an approach that takes accord of the ways consumers and consumer roles are framed in interactive
processes in markets, governance structures, and everyday life. Consumers in different countries assess their responsibilities
and their powers as consumers differently due to different institutionalizations within distinctive contexts. We also must take into account how the inertia
of ordinary consumption and the moral complexities of everyday life restrict the adoption of an active consumerist role. Hence,
the debate on political consumerism should make for a more realistic notion of ethical consumer-sovereignty and its role in
improving the workings of capitalism. In our view, these findings have severe implications for understanding both theories
of political consumption and the dynamics of political consumption per se. 相似文献
154.
防御性在中国传统村落的规划和建设中具有很高的研究价值。通过分析湖南传统村落在选址、空间形态、防火和建筑装饰等方面的防御性特征,指出传统村落的物质防御和精神防卫等防御理念具有明显的先进性与科学性。两个方面共同作用,所营造的传统村落的安全居住环境,是中国传统文化因素中的心理安全防御意识在具体环境中的物化体现,是中国传统哲学观念和生态环境观念的有机统一,指出传统村落的防御性在当今和谐社会宜居社区的规划和建设中的借鉴意义。 相似文献
155.
以室内环境的空气品质以及声、光、热环境为研究对象,根据实测数据,建立不满意百分比指标PD(predicteddissatisfied),基于熵权理论对整个室内环境进行评价。在多因素的室内环境评价过程中,该方法在以实测数据确定评价指标的相对重要程度后,根据各评价对象之间某些评价指标重要度的差异,自动调节各种差异对评价过程的影响,合理的优化了评价过程。以某小区6户人家家庭环境的物理、化学因素测试的数据进行综合评价,其结果与实际情况相吻合。说明该方法所得到的评价结果具有说服力。 相似文献
156.
在系统安全理论中,确定各基本事件的可靠度以实现所给定的系统安全目标值问题一直没有得到很好解决。笔者将可靠性分配理论与故障树分析方法相结合,提出了2个层次可靠度分配法:最小割集之间采取可靠度再分配法,对构成最小割集的各个基本事件之间采取等分配法。从而建立系统中各单元可靠度再分配量化模型。为便于应用,通过实例,详述系统各单元可靠性分配的计算过程。研究表明,运用该模型可准确、简便地计算出各单元的可靠度,使系统在给定的目标值条件下达到系统的安全性优化。 相似文献
157.
158.
Marion Babcock Bruce Mitchell 《Journal of the American Water Resources Association》1980,16(3):532-537
ABSTRACT: This study is an examination of the relationship between flooding and property values for an urban community in southwestern Ontario which has a lengthy history of flooding. As well, peoples’perceptions of the effect of flooding on property values is discussed. Analysis of sales prices and assessment data demonstrated no statistically significant differences in values of property for residences located in high- and low-risk areas either before or after a major flood in 1974. With both the high- and low-risk areas, sales prices after the 1974 flood were significantly higher than sales prices before the flood. The perceived property values followed a similar pattern. We concluded that differences in flood risk and flood experience did not adversely affect actual or perceived long-term property values. 相似文献
159.
Thomas E. Croley 《Journal of the American Water Resources Association》1974,10(6):1123-1132
ABSTRACT: Water resource development has progressed to the stage where various human factors are now being considered in reservoir design and operation. The introduction of human factor objectives complicates the problem since they are noncommensurate with other objectives and they are difficult to identify quantitatively. Some of the problems that now arise concern the proper methods for consideration of several different, sometimes subjectively identified, objectives in reservoir planning. The classical systems analysis approach to decision making for multiple objective problems is outlined and the inherent difficulties associated with multiple objectives and subjective estimates are identified. Techniques being used in reservoir design and operation are reviewed and discussed. An alternate technique for considering noncommensurate, subjectively identified, objectives, which relates the objectives in terms of real trade-off costs and eliminates the need for a priori estimates of objective worth is then presented. The method is illustrated with three examples, including a reservoir operation problem and a cooling tower design problem. 相似文献
160.
There is an urgent need to develop sound theory and practice for biodiversity offsets to provide a better basis for offset multipliers, to improve accounting for time delays in offset repayments, and to develop a common framework for evaluating in-kind and out-of-kind offsets. Here, we apply concepts and measures from systematic conservation planning and financial accounting to provide a basis for determining equity across type (of biodiversity), space, and time. We introduce net present biodiversity value (NPBV) as a theoretical and practical measure for defining the offset required to achieve no-net-loss. For evaluating equity in type and space we use measures of biodiversity value from systematic conservation planning. Time discount rates are used to address risk of non-repayment, and loss of utility. We illustrate these concepts and measures with two examples of biodiversity impact–offset transactions. Considerable further work is required to understand the characteristics of these approaches. 相似文献