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排序方式: 共有1038条查询结果,搜索用时 15 毫秒
131.
Although recent studies have suggested that environmental participation may be a countertrend to decreasing civic engagement in the United States, there are very few empirical studies that examine these claims. This paper studies participation in local environmental stewardship as such a countertrend. Using data collected from participants in the Watershed Stewards Academies (WSAs) of Maryland, we assess how these organisations are successful in mobilising individuals to be environmentally and civically engaged in their communities. We argue that hybrid organisations like the WSAs represent a countertrend to diminishing rates of civic engagement by offering citizens what a “paper-membership” cannot: the chance to lead their own environmental restoration projects, create tangible change in their communities, and network with other like-minded individuals. These environmental programmes serve to diversify democracy at the local level, providing a unique form of civic engagement and enriching the connections between individual citizens and their civic communities. 相似文献
132.
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134.
孙志国 《辽宁城乡环境科技》2011,(5):70-72
以朝阳市为例,分析了环境信访投诉案件产生的主要原因,主要包括城市规划布局不尽合理、环保前置审批制度落实不到位、相关部门执法尚未形成合力等,并针对朝阳市环境信访与投诉案件的形式和特点,提出了将环保工作纳入城市规划全过程、控制源头审批、建立完善信访制度等建议。 相似文献
135.
Decision making with option pricing and dynamic programming: development and application 总被引:1,自引:0,他引:1
In this study, an option pricing model and a dynamic programming model are developed. These models contribute to the improvement of the decision making process in two respects. First, these models allow for the own growth rate of mining costs to be incorporated into the analysis. Second, these models are developed to estimate the satisfactory gross revenue for investing, so that these models are helpful in analyzing multi-metal mines.The two models are applied to estimate the satisfactory revenue for investing in the Carlin east gold mine, Nevada, USA. The satisfactory revenue estimated by the option pricing model is found to be $42.2M, while that estimated by the dynamic programming model is found to be $44.4M. Since the revenue calculated on the basis of the current conditions is $36M, then the decision by option pricing and dynamic programming is to wait and not to invest now. Despite the difference between the two models in estimating and applying the discount rate, the two models generate the same decision. 相似文献
136.
The number of males in primate social groups: a comparative test of the socioecological model 总被引:2,自引:2,他引:0
Charles L. Nunn 《Behavioral ecology and sociobiology》1999,46(1):1-13
As applied to polygynous mammals, the socioecological model assumes that environmental risks and resources determine the
spatial and temporal distribution of females, which then sets male strategies for monopolizing fertile matings. The effects
of female spatial distribution (i.e., female number) and temporal overlap (female mating synchrony) have been examined in
comparative studies of primates, but the relative influence of these two factors on male monopolization potential (the number
of males) remains unclear. One particular problem is that female synchrony is more difficult to estimate than female number.
This paper uses multivariate statistical methods and three independent estimates of female synchrony to assess the roles of
spatial and temporal effects in the context of a phylogenetically corrected dataset. These analyses are based on sensitivity
analyses involving a total of four phylogenies, with two sets of branch length estimates for each tree, and one nonphylogenetic
analysis in which species values are used (because male behavior may represent a facultative response to the distribution
of females). The results show: (1) that breeding seasonality predicts male number (statistically significant in six out of
nine sensitivity tests); (2) that expected female overlap, after controlling for female group size using residuals, also accounts
for the number of males in primate groups (significant in eight out of nine tests), and (3) that actual estimates of female
mating synchrony predict male number, again after correcting for female group size (significant in five out of nine tests).
Nonsignificant results are in the predicted direction, and female group size is significant in all statistical tests. These
analyses therefore demonstrate an independent influence of female temporal overlap on male monopolization strategies in mammalian
social systems.
Received: 24 July 1998 / Received in revised form: 5 February 1999 / Accepted: 7 February 1999 相似文献
137.
阐述了小城镇开展生态监测的目的和意义,以及小城镇生态监测指标体系的建立原则,介绍了城市生态子系统环境监测指标体系、农村生态子系统环境监测指标体系和自然生态子系统环境监测指标体系的具体内容,以及相关的监测方法与技术。 相似文献
138.
本文主要介绍加拿大新的《机动车辆约束系统和加高座椅安全法规》(SOR/2011-16)的相关内容,同时对儿童汽车座椅的研究与测试方法也进行了详细描述,以对我国相关行业提供借鉴。 相似文献
139.
140.
矿物超细颗粒在自然环境中普遍存在,具有独特的环境行为和效应,对元素地球化学循环、污染物迁移转化和生态环境演变等有重要影响.矿物超细颗粒的环境行为和效应与其形成过程和结构特征密切相关.综述了物理、化学和生物过程驱动的矿物超细颗粒的形成机制,介绍了用于表征矿物超细颗粒结构特征的显微镜、光谱、质谱和同步辐射技术,分析了矿物超细颗粒在环境中的迁移转化及其与污染物的吸附、氧化还原和催化转化作用,总结了矿物超细颗粒的食物链积累、生物和生态毒性等环境效应,并对颗粒结晶路径、风险管控和微纳界面调控等重要研究方向进行了展望.超细颗粒是连接微观物质与宏观矿物晶体之间的桥梁,全面认识复杂基质中矿物颗粒的环境属性及其与污染物的微观作用机制,有助于指导矿物超细颗粒在环境污染修复中的应用,从而优化功能材料的设计,促进绿色低碳纳米技术的发展. 相似文献