首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   529篇
  免费   24篇
  国内免费   2篇
安全科学   74篇
废物处理   4篇
环保管理   147篇
综合类   111篇
基础理论   99篇
污染及防治   6篇
评价与监测   4篇
社会与环境   94篇
灾害及防治   16篇
  2025年   1篇
  2024年   22篇
  2023年   18篇
  2022年   12篇
  2021年   17篇
  2020年   13篇
  2019年   13篇
  2018年   15篇
  2017年   23篇
  2016年   9篇
  2015年   15篇
  2014年   13篇
  2013年   25篇
  2012年   28篇
  2011年   28篇
  2010年   18篇
  2009年   27篇
  2008年   19篇
  2007年   26篇
  2006年   31篇
  2005年   23篇
  2004年   19篇
  2003年   14篇
  2002年   13篇
  2001年   10篇
  2000年   19篇
  1999年   12篇
  1998年   9篇
  1997年   11篇
  1996年   11篇
  1995年   11篇
  1994年   6篇
  1993年   5篇
  1992年   1篇
  1991年   1篇
  1990年   1篇
  1988年   1篇
  1986年   1篇
  1985年   1篇
  1983年   2篇
  1980年   2篇
  1978年   3篇
  1977年   1篇
  1975年   1篇
  1973年   1篇
  1972年   1篇
  1971年   2篇
排序方式: 共有555条查询结果,搜索用时 15 毫秒
381.
讨论了土地复垦投资内涵、特点、基本原则、基本运行过程、基本模式及国内外土地复垦投资现状及问题。  相似文献   
382.
环境保护投资的市场化运作   总被引:2,自引:0,他引:2  
环境保护投资是解决环境问题的重要保障。分析了我国环境保护投资存在的主要问题及其原因,对我国环境保护投资的市场化运作进行分析,提出了社会主义市场经济体制下筹集环境保护投资、环境保护管理及环境保护设施管理的主要措施。  相似文献   
383.
上海市环保产业科技投入位居全国前列.为了进一步提高投资绩效,需要配套完善相关制度.因此对上海市环保产业研发提出了加大投入、调整投入结构、综合运用财政工具的财政政策,以及深化环保税收政策建议;设计了上海市“政府投入积极导向、企业科研投入为主、金融信贷风险投资支撑,社会多方参与补充”的多元化环保产业科技投入体系.  相似文献   
384.
环境绿化投资综合效益度量方法及其应用研究   总被引:1,自引:0,他引:1  
随着中国城镇规模的不断扩张,环境绿化的综合效益度量问题越来越受到人们的普遍重视。本文主要从中国城镇郊区环境绿化投资分析入手,重点研究环境绿化中经济效益、环境效益和社会效益的综合度量问题,建立了环境绿化综合效益的度量模型并进行了应用分析,为城镇郊区环境绿化的综合分析提供了一种行之有效的定量方法。  相似文献   
385.
GIM(1)灰色模型预测环保投资趋势的可行性探析   总被引:4,自引:0,他引:4  
环保投资作为环保系统的一个子系统,并不一定具有指数函数规律。本文利用GIM(1)灰色模型,探析了它在环保投资趋势预测应用中的可行性。初步应用表明,在序列不完全满足光滑化条件时,GIM(1)灰色模型对系统变量的“白化”能力较GM(1,1)强,而与GSM(1)灰色模型相当,信息利用率高,是分析、预测环保投资动态发展趋势一条切实可行的途径。  相似文献   
386.
推导一个描述私人利润率和社会利润率之间的新公式。该公式涉及的2个相关的环境参数为:环境投资占国民收入的百分比(λ);从环境投资角度出发定义的环境改善的弹性(η)。公式表明,从环境的观点出发,社会利润率或环境贴率应该随则系统地降低。此外,本文还引用了“环境阻力”的概念来论述模型的意义,同时还简要地讨论了环境阻力的计算方法。  相似文献   
387.
         下载免费PDF全文
Caught between ongoing habitat destruction and funding shortfalls, conservation organizations are using systematic planning approaches to identify places that offer the highest biodiversity return per dollar invested. However, available tools do not account for the landscape of funding for conservation or quantify the constraints this landscape imposes on conservation outcomes. Using state‐level data on philanthropic giving to and investments in land conservation by a large nonprofit organization, we applied linear regression to evaluate whether the spatial distribution of conservation philanthropy better explained expenditures on conservation than maps of biodiversity priorities, which were derived from a planning process internal to the organization and return on investment (ROI) analyses based on data on species richness, land costs, and existing protected areas. Philanthropic fund raising accounted for considerably more spatial variation in conservation spending (r2 = 0.64) than either of the 2 systematic conservation planning approaches (r2 = 0.08–0.21). We used results of one of the ROI analyses to evaluate whether increases in flexibility to reallocate funding across space provides conservation gains. Small but plausible “tax” increments of 1–10% on states redistributed to the optimal funding allocation from the ROI analysis could result in gains in endemic species protected of 8.5–80.2%. When such increases in spatial flexibility are not possible, conservation organizations should seek to cultivate increased support for conservation in priority locations. We used lagged correlations of giving to and spending by the organization to evaluate whether investments in habitat protection stimulate future giving to conservation. The most common outcome at the state level was that conservation spending quarters correlated significantly and positively with lagged fund raising quarters. In effect, periods of high fund raising for biodiversity followed (rather than preceded) periods of high expenditure on land conservation projects, identifying one mechanism conservation organizations could explore to seed greater activity in priority locations. Our results demonstrate how limitations on the ability of conservation organizations to reallocate their funding across space can impede organizational effectiveness and elucidate ways conservation planning tools could be more useful if they quantified and incorporated these constraints.  相似文献   
388.
Impressive variation in egg colouration among birds has puzzled evolutionary biologists for a long time. The most frequently studied selective forces moulding egg colouration—predation and brood parasitism—have either received little empirical support or may play a role in only a minority of species. A novel hypothesis has suggested that egg colour may be significantly influenced by sexual selection. Females may deposit a blue-green pigment biliverdin into eggshells instead of using it for themselves as a powerful antioxidant. By this handicap, females may signal their quality to males, which are then hypothesized to increase their paternal effort. We experimentally tested the hypothesis in the collared flycatcher (Ficedula albicollis), a species laying blue-green eggs. We cross-fostered clutches between nests to disentangle effects of female/territory quality and egg colour on paternal effort and nestling quality. The results supported two assumptions of sexual signalling through egg colour hypothesis: Blue pigment seems to be a limited resource for females, and female quality is positively correlated with the intensity of the blue-green colour. However, we did not find support for the main prediction of the hypothesis, as male parental effort parameters (feeding frequencies to nestlings and intensity of nest defence) were unrelated to egg colour. We discuss possible reasons for the discrepancy between our results and previous correlative analyses that supported the hypothesis that blue egg colour may be a postmating, sexually selected signal in females.  相似文献   
389.
Recent evidence has revealed an apparently high degree of control by female birds over the physiological aspects of their reproduction and offspring sex allocation, consistent with adaptive hypotheses of sex allocation and differential investment in their offspring. In the house sparrow, we investigated possible mechanisms that may be used by females to enhance the fitness returns from a reproductive effort. Using molecular techniques, we demonstrate that house sparrow eggs containing male embryos are significantly larger than those containing female embryos. We also found that male embryos were laid randomly with respect to laying order. We speculate that this sexual dimorphism of eggs is adaptive, because male house sparrows show greater variance in condition-dependent reproductive success than females. More important, the result provides further evidence of the ability of females to detect or control ovulation of either male or female ova and to differentially invest in one sex over the other. Received: 19 January 2000 / Revised: 29 June 2000 / Accepted 20 July 2000  相似文献   
390.
为调整外商中的投资环境保护问题,我佃环境法已经形成了一个包括宪法性规范,专项单行立法,地方性法规及国际公约等多层次的法律框架。我国将外商投资项目分为鼓励允许、限制禁止四类,并规定了外商投资应遵循的若干环境管理措施。但总体上看我国环境法还存在立法和执法缺陷,亟待完善。  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号