全文获取类型
收费全文 | 1150篇 |
免费 | 102篇 |
国内免费 | 173篇 |
专业分类
安全科学 | 59篇 |
废物处理 | 7篇 |
环保管理 | 269篇 |
综合类 | 542篇 |
基础理论 | 104篇 |
污染及防治 | 37篇 |
评价与监测 | 47篇 |
社会与环境 | 311篇 |
灾害及防治 | 49篇 |
出版年
2024年 | 7篇 |
2023年 | 17篇 |
2022年 | 46篇 |
2021年 | 61篇 |
2020年 | 36篇 |
2019年 | 34篇 |
2018年 | 39篇 |
2017年 | 54篇 |
2016年 | 50篇 |
2015年 | 57篇 |
2014年 | 33篇 |
2013年 | 78篇 |
2012年 | 80篇 |
2011年 | 98篇 |
2010年 | 60篇 |
2009年 | 59篇 |
2008年 | 48篇 |
2007年 | 65篇 |
2006年 | 63篇 |
2005年 | 43篇 |
2004年 | 49篇 |
2003年 | 43篇 |
2002年 | 38篇 |
2001年 | 18篇 |
2000年 | 40篇 |
1999年 | 33篇 |
1998年 | 15篇 |
1997年 | 21篇 |
1996年 | 19篇 |
1995年 | 18篇 |
1994年 | 23篇 |
1993年 | 12篇 |
1992年 | 8篇 |
1991年 | 4篇 |
1990年 | 8篇 |
1989年 | 6篇 |
1988年 | 4篇 |
1987年 | 5篇 |
1986年 | 3篇 |
1985年 | 2篇 |
1983年 | 2篇 |
1982年 | 2篇 |
1980年 | 5篇 |
1979年 | 4篇 |
1978年 | 3篇 |
1975年 | 2篇 |
1974年 | 1篇 |
1973年 | 1篇 |
1972年 | 3篇 |
1971年 | 2篇 |
排序方式: 共有1425条查询结果,搜索用时 472 毫秒
941.
在查明多个突出影响因素与突出危险性之间内在联系的基础上,应用地质动力区划方法确定区域地质构造模型,并结合地应力测量方法和数值模拟,综合应用VB、VC完成模式识别系统设计和应用软件开发,在地理信息系统(GIS)支持下建立多因素模式识别模型.用多因素模式识别预测方法进行煤与瓦斯突出危险性的区域预测,划分淮南矿务局谢一矿井田的煤与瓦斯突出危险区、突出威胁区和无突出危险区,对煤与瓦斯突出危险性做出评估. 相似文献
942.
943.
长三角区域性应急救援体系的建设 总被引:1,自引:2,他引:1
区域性应急救援体系建设是区域一体化的必然要求,也是一个全新的研究课题。以长江三角洲地区为例,对当前区域性应急救援体系建设过程中出现的主要问题进行了分析,并从法制、体制和机制等方面提出了对策。 相似文献
944.
Ken Eng Gary D. Tasker P.C.D. Milly 《Journal of the American Water Resources Association》2005,41(1):135-143
ABSTRACT: Region‐of‐influence (RoI) approaches for estimating stream flow characteristics at ungaged sites were applied and evaluated in a case study of the 50‐year peak discharge in the Gulf‐Atlantic Rolling Plains of the southeastern United States. Linear regression against basin characteristics was performed for each ungaged site considered based on data from a region of influence containing the n closest gages in predictor variable (PRoI) or geographic (GRoI) space. Augmentation of this count based cutoff by a distance based cutoff also was considered. Prediction errors were evaluated for an independent (split‐sampled) dataset. For the dataset and metrics considered here: (1) for either PRoI or GRoI, optimal results were found when the simpler count based cutoff, rather than the distance augmented cutoff, was used; (2) GRoI produced lower error than PRoI when applied indiscriminately over the entire study region; (3) PRoI performance improved considerably when Rol was restricted to predefined geographic subregions. 相似文献
945.
Summary This study suggested that cell-cycle kinetics, DNA replication and DNA repair react to magnetic fields differently. During
their culture growth cycle, which lasted about five days, Friend erythroleukemia cells were either kept in the absence of
magnetic fields in a magnetically shielded room or irradiated in a solenoid with 70 μT at 50 Hz plus 45 μT DC of the Earth:
some cells grew without inducer of in vitro differentiation; others were induced to differentiate hemoglobin through dimethylsulfoxide. It emerged that, during a single
culture growth cycle, while proliferation was slightly accelerated by the magnetic-field irradiation achieved in the solenoid
both in undifferentiating and dimethylsulfoxide-differentiating cells, DNA replication did not appear to significantly depend
on the magnetic-field deprivation achieved in the magnetically shielded room. However, as a result of a 318-day long magnetic-field
irradiation in the solenoid, DNA replication remained unchanged in undifferentiating cells and partially inhibited in dimethylsulfoxide-differentiating
cells. Following the same long magnetic-field irradiation in the solenoid, the amount of labelled repair patches in the parental
DNA strands was slightly reduced. 相似文献
946.
湖北区域旅游空间发展模式与战略布局 总被引:3,自引:0,他引:3
对区域旅游及其空间增长规律作了总结,根据湖北旅游业发展的现实基础和所面临的市场竞争形势,指出湖北旅游业发展应该走区域一体化战略模式,并通过点状开发、线状开发和网状开发形成一批能奠定湖北旅游形象,构建网络格局的中心旅游城市、品牌旅游线路和旅游局域网.根据该模式发展的要求,提出大武汉都市旅游区、鄂西南大三峡与民俗风情旅游区、鄂西北武当文化与山岳生态旅游区的布局,将武汉、宜昌和十堰(武当山)作为引导未来湖北旅游发展的三大支撑点来建设的思路. 相似文献
947.
948.
949.
近年来,随着我国社会和经济改革的逐渐深入,区域协调发展问题日益凸现和发展,成为制约我国社会和经济进一步发展的瓶颈。综述了我国新时期区域协调发展的主要研究进展,展望了地理学在这一领域的发展趋势。 相似文献
950.
In case of large data matrices comparative evaluations of objects/regions with the technique of Hasse diagrams may be troublesome due to a messy system of lines in the graphical representation. Here fuzzy clustering leads to useful simplifications because regions with slightly different pollution pattern are grouped together. However, fuzzy clustering implies to introduce a threshold value for the membership of an object to a cluster and to select the best number of clusters. Therefore many arbitrarities evolve. Within the systematic study presented here we found that some objects are very stable against variations of the threshold value and the number of cluster whereas other objects behaves different. According to their behaviour we investigated a classification of the objects. Formal Concept Analysis shows that in some cases specific pollution pattern imply the membership to one of these classes. For example objects which are characterized by high Pb-, Zn-concentration and moderate S-concentration imply a high stability against variants of the clustering process. Further implications are described in the paper. 相似文献