全文获取类型
收费全文 | 6752篇 |
免费 | 425篇 |
国内免费 | 1499篇 |
专业分类
安全科学 | 429篇 |
废物处理 | 326篇 |
环保管理 | 648篇 |
综合类 | 2930篇 |
基础理论 | 1704篇 |
环境理论 | 1篇 |
污染及防治 | 1568篇 |
评价与监测 | 432篇 |
社会与环境 | 418篇 |
灾害及防治 | 220篇 |
出版年
2024年 | 14篇 |
2023年 | 107篇 |
2022年 | 246篇 |
2021年 | 260篇 |
2020年 | 241篇 |
2019年 | 161篇 |
2018年 | 304篇 |
2017年 | 346篇 |
2016年 | 380篇 |
2015年 | 309篇 |
2014年 | 337篇 |
2013年 | 399篇 |
2012年 | 772篇 |
2011年 | 536篇 |
2010年 | 300篇 |
2009年 | 284篇 |
2008年 | 335篇 |
2007年 | 320篇 |
2006年 | 288篇 |
2005年 | 564篇 |
2004年 | 673篇 |
2003年 | 547篇 |
2002年 | 173篇 |
2001年 | 135篇 |
2000年 | 135篇 |
1999年 | 111篇 |
1998年 | 63篇 |
1997年 | 68篇 |
1996年 | 47篇 |
1995年 | 49篇 |
1994年 | 28篇 |
1993年 | 30篇 |
1992年 | 36篇 |
1991年 | 17篇 |
1990年 | 16篇 |
1989年 | 10篇 |
1988年 | 4篇 |
1987年 | 5篇 |
1986年 | 2篇 |
1982年 | 2篇 |
1981年 | 2篇 |
1975年 | 2篇 |
1974年 | 2篇 |
1972年 | 2篇 |
1971年 | 2篇 |
1969年 | 2篇 |
1966年 | 2篇 |
1962年 | 1篇 |
1961年 | 1篇 |
1957年 | 1篇 |
排序方式: 共有8676条查询结果,搜索用时 15 毫秒
11.
12.
13.
VariationfeaturesofprecipitationinGuangxiUnevendistributionofprecipitationinareas ByreasonofcomplexlandforminGuangxi,theprecipitationvariesindifferentregionsandisgenerallyabundantinthesouthandthenorth,littleinthemiddleregion;abundantintheeastandlittleinthewest;abundantinhillyareasandlittleintherivervalleysandbasins;abundantinwindwardslopesandlittleinleewardslopes;abundantincoastlandandlittleinis lands.Therearemainly 4 pluvialregionsand 2littlerainfallregions.The 4pluvialregionswithprecipitat… 相似文献
14.
15.
与国民经济长期高增长相背离,证券市场出现了深幅下跌,投资者承受了巨大的投资风险,究其原因,体制性缺陷是重要因素之一。笔者认为,我国证券市场的体制性缺陷主要表现在市场经济环境不够完备、法律法规体系不十分健全、监管体制不力、证券市场的功能定位扭曲、股权分置问题久拖难决等方面。目前该体制性缺陷是导致我国证券市场长期下跌的重要原因,也给证券投资者带来了巨大的投资风险。只有加快改革、完善法律和监管体制,我国证券市场才能具有投资价值并健康发展。 相似文献
16.
聚合硅酸硫酸铝铁的制备与应用 总被引:4,自引:2,他引:4
在n(Fe A1)/n(Si)为0.5~1.0、n(Al)/n(Fe)为2.5~3.0、SiO2质量分数为2.3%、硅酸钠溶液的活化pH为5.5、硅酸钠溶液的活化时间为12min或SiO2的质量分数为2.0%、硅酸钠溶液的活化pH为6.0、硅酸钠溶液的活化时间为3min的条件下,制备出的聚合硅酸硫酸铝铁对废水的除浊效果最佳,除浊率大于98%。 相似文献
17.
Public Perception of Flood Hazard in the Niger Delta,Nigeria 总被引:3,自引:0,他引:3
Summary Our study had the aim of understanding how floodplain dwellers regard the risk of flooding. About 500 questionnaires were
administered to landowners in the selected settlements in the study area using systematic random sampling. The results of
analysis show, among other things, that the population regards most important the causes of floods as heavy, prolonged rainfall
and river overflow. Nevertheless, they have little knowledge of the frequency of severe floods, and flood alleviation schemes.
Most flood victims do not get compensation or relief during flood disaster, and the reason why they remain in the study area
is influenced by their occupations, especially fishing, subsistence agriculture, and the presence of crude oil in the region
which has attracted many migrants who cannot afford the high cost of accommodation and are therefore forced to live in vulnerable
areas of the floodplain. Finally, the study concludes that flood control in the region needs the cooperation of government,
community efforts and an enlightenment programmes through environmental education and mass media. 相似文献
18.
A study of a watershed planning process in the Cache River Watershed in southern Illinois revealed that class divisions, based
on property ownership, underlay key conflicts over land use and decision-making relevant to resource use. A class analysis
of the region indicates that the planning process served to endorse and solidify the locally-dominant theory that landownership
confers the right to govern. This obscured the class differences between large full-time farmers and small-holders whose livelihood
depends on non-farm labor. These two groups generally opposed one another regarding wetland drainage. Their common identity
as “property owner” consolidated the power wielded locally by large farmers. It also provided an instrument – the planning
document – for state and federal government agencies to enhance their power and to bring resources to the region. The planning
process simultaneously ameliorated conflicts between government agencies and the large farmers, while enhancing the agencies’
capacity to reclaim wetlands. In this contradictory manner, the plan promoted the environmental aims of many small-holders,
and simultaneously disempowered them as actors in the region’s political economy.
An erratum to this article is available at . 相似文献
19.
20.