全文获取类型
收费全文 | 1415篇 |
免费 | 89篇 |
国内免费 | 171篇 |
专业分类
安全科学 | 172篇 |
废物处理 | 57篇 |
环保管理 | 283篇 |
综合类 | 599篇 |
基础理论 | 258篇 |
环境理论 | 4篇 |
污染及防治 | 70篇 |
评价与监测 | 25篇 |
社会与环境 | 84篇 |
灾害及防治 | 123篇 |
出版年
2023年 | 25篇 |
2022年 | 31篇 |
2021年 | 43篇 |
2020年 | 54篇 |
2019年 | 46篇 |
2018年 | 36篇 |
2017年 | 47篇 |
2016年 | 51篇 |
2015年 | 59篇 |
2014年 | 82篇 |
2013年 | 89篇 |
2012年 | 81篇 |
2011年 | 121篇 |
2010年 | 69篇 |
2009年 | 92篇 |
2008年 | 68篇 |
2007年 | 71篇 |
2006年 | 79篇 |
2005年 | 70篇 |
2004年 | 55篇 |
2003年 | 51篇 |
2002年 | 41篇 |
2001年 | 29篇 |
2000年 | 46篇 |
1999年 | 26篇 |
1998年 | 23篇 |
1997年 | 21篇 |
1996年 | 22篇 |
1995年 | 27篇 |
1994年 | 21篇 |
1993年 | 14篇 |
1992年 | 12篇 |
1991年 | 12篇 |
1990年 | 6篇 |
1989年 | 6篇 |
1988年 | 9篇 |
1987年 | 1篇 |
1986年 | 3篇 |
1985年 | 2篇 |
1984年 | 8篇 |
1983年 | 1篇 |
1982年 | 5篇 |
1981年 | 6篇 |
1980年 | 3篇 |
1979年 | 3篇 |
1978年 | 3篇 |
1977年 | 1篇 |
1973年 | 1篇 |
1971年 | 1篇 |
1970年 | 1篇 |
排序方式: 共有1675条查询结果,搜索用时 62 毫秒
151.
武钢三烧区域改建了二台大连三洋蒸汽型双效溴化锂吸收式制冷机。叙述了该改建项目的主机选型、参数选定、设计特点等。 相似文献
152.
Science–policy interfaces are avenues for finding solutions for environmental challenges through strengthening collaborations between research disciplines and public administrations. Here we present a methodology for the conduct of science–policy interfaces between scientists and policymakers for addressing day-to-day environmental problems in the southeastern Spanish drylands. A knowledge brokering approach based on six consecutive workshops was used to facilitate mutual understanding and trust between scientists and policymakers. Water policy and biodiversity loss were identified as major environmental concerns in the region, and 12 final environmental problems were agreed as priorities. A graphical tool was used for diagnosing each environmental problem according to the available scientific knowledge, the current regulatory capacity of administrations, and the level of public engagement necessary for addressing the problem. The use of the graphical tool also allowed for (a) the clarification of roles involved in problem solving, and (b) the promotion of a culture of shared responsibility for the implementation of management actions based on collaborative work. We discuss lessons learned and propose recommendations for future experiences. 相似文献
153.
154.
ABSTRACT: Four alternate schemes often used to deal with a water shortage are: physical rationing, lifeline with increasing block rates, rationing with resale, and pure price rationing. Each of these are analyzed using a supply-demand framework. The theoretical results are applied to a representative California water district and the welfare loss is calculated for a hypothetical 20 percent reduction in water supply for six different income classes. We find that reliance on schemes using the price mechanism in one form or another is clearly superior, in terms of welfare loss, as a means of dealing with a water shortage. 相似文献
155.
156.
The climate impacts of energy technologies are frequently assessed using equivalency metrics, which convert emissions of multiple greenhouse gases to a common scale. Numerous metrics have been proposed that incorporate, in different ways, information about the time-dependent impacts of gases. However, more focus has been placed on proposing metrics than on testing their performance in real-world use cases. Here we present a testing approach that simulates how metrics would affect the selection of energy technology portfolios that comply with a CO2-equivalent emissions cap. Unintended radiative forcing outcomes can occur, emphasizing the need to test metrics in a practical context. We demonstrate the approach for policies designed to limit radiative forcing and discuss extensions to limits on temperature or economic impacts. Metric performance is evaluated by (i) how much actual radiative forcing overshoots the intended stabilization level and (ii) the level of energy consumption permitted. We use this testing approach to study a variety of metrics based on an estimated radiative forcing stabilization time under two climate policy goals. We find that these goal-inspired metrics, if chosen carefully, can exhibit performance improvements over the standard global warming potential (GWP) while maintaining its transparency and ease-of-use. These alternative metrics can significantly reduce the overshoot in radiative forcing observed with the GWP, at a small cost in energy consumption. Moreover, simple metrics can exhibit similar performance improvements to more complex ones. 相似文献
157.
Fabio Orecchini 《Sustainability Science》2007,2(2):245-252
Human society consumes resources that it is not able to reproduce. Human activities are still based on “open cycles,” starting
from a condition of natural environmental balance and reaching an environmental imbalance. The challenging scope of scientific
and technological research towards sustainability appears clear if it is based on this analysis: to find development systems
based on “closed cycles” of resources. The challenging objective of realizing closed cycles leads to a definition of sustainability
that indicates the path to sustainable development, as well as stating the general principle. It also provides a key to the
qualitative measurement of sustainability. This means that the sustainability level of a system can be measured by measuring
its capacity to avoid the consumption of resources. Zero consumption is a necessary condition for sustainability, and brings
about as a side effect the highly desired “zero-waste” result. Materials entering the proposed endless scheme pass through
the process of usefulness without losing their capacity to feed the system again after being used. Thus, the concept of “consumption”
itself is replaced by one of “use” when resources are inserted into closed loops capable of feeding human development. The
application of the closed cycle sustainability criterion particularly displays its feasibility, and a theoretical guiding
role, in the energy sector. Energy vectors such as hydrogen and electricity enable the closure of the energy resources loop
by effectively approaching the objective of “zero consumption” (and the side result of “zero waste”) through already demonstrated
technological solutions. 相似文献
158.
Simultaneous photocatalytic reduction of poisonous Cr(VI) and Ni(II) ions, coupled with photocatalytic oxidation of sodium dodecyl benzene sulfonate (SDBS) were studied with a trace amount of commercial titania nanoparticles and by means of a direct-photo-irradiation reactor. The co-presence of metal ions and SDBS causes metal ions reduction as well as SDBS oxidation to enhance and energy efficiency to improve. XRD, XPS and FTIR analysis were used to characterize TiO2 particles before and after usage with the aim of evaluating the mechanism of reactions. The effect of major operating parameters, pH and temperature, was investigated. Under conditions of [Cr(VI)]0 = [Ni(II)]0 = 5 mg/L, [SDBS]0 = 10 mg/L, [TiO2] = 40 mg/L, pH 6 and T = 35 °C; the removal efficiencies of 55.4%, 71.2% and 57.2% were obtained, respectively, for Cr(VI) and Ni(II) reduction, as well as for SDBS oxidation, after 110 min operation. The relevant kinetic model jointed with the Arrhenius equation was introduced. Pseudo-first-order reactions are relevant. Energy consumption (electrical and thermal) evaluations revealed that operations at higher temperatures provide significant cost reduction. Meantime, a criterion was proposed for a consistent assessment of this kind of processes. 相似文献
159.
Emerging attention has been given to the use of biomass in local areas for its contribution to reducing fossil fuel dependence and mitigating global warming. The objective of the present study is to develop a method that quantitatively assesses the effects of local biomass projects on fossil fuel consumption and greenhouse gas (GHG) emission. A practical method based on a life cycle approach is proposed and applied to a case of bioethanol project in Miyako Islands of Japan. The project is aiming to produce bioethanol from molasses within the islands, and to replace the entire gasoline consumed in the islands to E3 fuel (i.e., a mixture of 3% ethanol and 97% gasoline by volume). The assessment using the developed method revealed that, first, the complete shift from gasoline to E3 fuel allows for decreases in fossil fuel consumption and GHG emission. Second, the performance of the project is improved by the integration of the ethanol plant and the sugar factory. Moreover, the assessment found that, in small-scale bioethanol projects, the contribution of capital goods to life cycle fuel consumption and GHG emission is not negligible. 相似文献
160.
气溶胶颗粒物在壁面的沉积率系数模型的研究已经成为现代气溶胶动力学研究的重要课题.本文通过实验腔测量和理论分析相结合,对Koivisto等(2012)提出的平均方法模型(AM)中的关键参数(即时间间隔)的选取和对测量数据量的要求两个问题进行研究.选取目前广泛使用的最小二乘法模型(LSM)和Lai和Nazaroff(2000)提出的理论分析模型进行对比.研究发现,AM模型中的时间间隔这一关键参数,应由目前的50矫正为20;AM模型和LSM模型均要求实验测量数据个数等于或者大于10,但是AM模型在小数据量情况下的预测结果更精确. 相似文献