全文获取类型
收费全文 | 2452篇 |
免费 | 162篇 |
国内免费 | 703篇 |
专业分类
安全科学 | 229篇 |
废物处理 | 144篇 |
环保管理 | 186篇 |
综合类 | 1428篇 |
基础理论 | 347篇 |
污染及防治 | 487篇 |
评价与监测 | 168篇 |
社会与环境 | 178篇 |
灾害及防治 | 150篇 |
出版年
2024年 | 9篇 |
2023年 | 44篇 |
2022年 | 141篇 |
2021年 | 113篇 |
2020年 | 110篇 |
2019年 | 94篇 |
2018年 | 128篇 |
2017年 | 104篇 |
2016年 | 90篇 |
2015年 | 130篇 |
2014年 | 203篇 |
2013年 | 199篇 |
2012年 | 178篇 |
2011年 | 175篇 |
2010年 | 163篇 |
2009年 | 164篇 |
2008年 | 145篇 |
2007年 | 146篇 |
2006年 | 126篇 |
2005年 | 73篇 |
2004年 | 104篇 |
2003年 | 102篇 |
2002年 | 114篇 |
2001年 | 119篇 |
2000年 | 84篇 |
1999年 | 75篇 |
1998年 | 41篇 |
1997年 | 28篇 |
1996年 | 34篇 |
1995年 | 22篇 |
1994年 | 17篇 |
1993年 | 11篇 |
1992年 | 5篇 |
1991年 | 9篇 |
1990年 | 4篇 |
1989年 | 4篇 |
1988年 | 2篇 |
1987年 | 1篇 |
1986年 | 1篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1982年 | 3篇 |
排序方式: 共有3317条查询结果,搜索用时 46 毫秒
551.
With the development of rural pollution, its characteristic and institutional factor should be studied for pollution control through economics and sociology. Based on the data gathered from investigations by several government sectors, rural environmental pollution can be divided into two types by its sources: internal source type and external source type. The internal source type is the main component of rural pollution at present, which can be further divided into three types. Research shows that the contributing institutional factors of rural pollution issues and the effectiveness of environmental management system over rural pollution can be summarized as distinctiveness. In essence, the rural pollution issue results from the dualism of rural and urban areas’ inadaptability to rural modernization. In detail, the contributing factors can be summed up on three institutional levels. There are obvious loopholes in rural environmental management system which, in the meantime, is incapable and inadaptable to rural pollution control. There exist similar questions in the related public service system, which are intensified by inappropriate reform which brought about incompatible incentive in the recent years. However, in the eleventh five-year plan period, there are advantageous trends in the three institutional levels. 相似文献
552.
Combustion and inorganic bromine emission of waste printed circuit boards in a high temperature furnace 总被引:1,自引:0,他引:1
High temperature combustion experiments of waste printed circuit boards (PCBs) were conducted using a lab-scale system featuring a continuously-fed drop tube furnace. Combustion efficiency and the occurrence of inorganic bromine (HBr and Br2) were systematically studied by monitoring the main combustion products continuously. The influence of furnace temperature (T) was studied from 800 to 1400 °C, the excess air factor (EAF) was varied from 1.2 to 1.9 and the residence time in the high temperature zone (RTHT) was set at 0.25, 0.5, or 0.75 s.Combustion efficiency depends on temperature, EAF and RTHT; temperature has the most significant effect. Conversion of organic bromine from flame retardants into HBr and Br2 depends on temperature and EAF. Temperature has crucial influence over the ratio of HBr to Br2, whereas oxygen partial pressure plays a minor role. The two forms of inorganic bromine seem substantially to reach thermodynamic equilibrium within 0.25 s. High temperature is required to improve the combustion performance: at 1200 °C or higher, an EAF of 1.3 or more, and a RTHT exceeding 0.75 s, combustion is quite complete, the CO concentration in flue gas and remained carbon in ash are sufficiently low, and organobrominated compounds are successfully decomposed (more than 99.9%).According to these results, incineration of waste PCBs without preliminary separation and without additives would perform very well under certain conditions; the potential precursors for brominated dioxins formation could be destroyed efficiently. Increasing temperature could decrease the volume percentage ratio of Br2/HBr in flue gas greatly. 相似文献
553.
计算机辅助事故树分析中的图形输入法 总被引:2,自引:1,他引:1
笔者提出计算机辅助事故树分析中事故树数据的图形输入法。通过详细讨论数据采集过程中数据结构的选用和算法设计 ,不但能方便地实现计算机辅助事故树绘图 ,而且在绘图的同时得到事故树的全部数据 ,进而可对事故树进行全部定性和定量分析。这种方法是计算机辅助事故树分析中绘图和数据输入方法的重要补充 ,同时也将有益于其他类型树及图的绘制和分析。最后 ,给出了一个实例 ,应用图形输入法得到满意的结果。该方法不仅是事故树的新绘制方法 ,也是全新的事故树数据输入法 ,是事故树算法的拓展和补充 相似文献
554.
555.
采用失重、电化学法研究了异喹啉季铵盐在 1mol/L盐酸溶液中对A3钢的缓蚀行为及吸附规律。实验表明 ,异喹啉季铵盐是一种阴、阳极混合型缓蚀剂 ,其缓蚀性能优良 ,在A3钢表面产生化学吸附 ,吸附过程为放热反应。 相似文献
556.
我国粮食安全保障中改善农业环境的途径 总被引:3,自引:0,他引:3
本文分析了我国粮食安全及粮食持续生产所依托的农业环境状况。从我国粮食生产状况与经济发展水平看,全国粮食生产处于结构性过剩与低水平安全中,区域性粮食安全与不安全并存;耕地资源、水资源以及农民的经济收入状况等均不容乐观,加之自然灾害加重,粮食生产的环境成本将随之增加,这将影响我国未来粮食安全。为此,本文提出了走农业集约化道路是解决我国粮食安全与改善环境的基本途径。 相似文献
557.
558.
青海湟水流域可持续发展中的主要问题与对策 总被引:1,自引:0,他引:1
湟水流域是带动青海经济腾飞的重要地带 ,在我国大西北开发中起着“强东拓西”的作用。分析了湟水流域在区域发展过程中存在的主要问题 ,提出了可持续发展的对策。 相似文献
559.
以ETM 影像数据为基础,利用景观分析软件Fragstats对唐家河自然保护区植被景观分别从东西、南北、西北至东南3个方向进行空间梯度分析.结果表明,沿东西方向,景观多样性呈现"升-降-升"的波动变化趋势,破碎化程度与复杂度降低;沿北南方向,景观多样性、复杂度以及连接度逐渐下降,但破碎度增加,形状趋于复杂;沿西北至东南方向,景观多样性与复杂度均表现出"降-升-降-升"的波动变化趋势;在西北部至中部斑块邻近度相对较高,变化较为明显;而东南部相对较低,变化幅度小.唐家河自然保护区所处的自然条件是其景观格局梯度变化形成的主要原因和先决条件,植物群落的空间格局明显受水文地貌特征的控制. 相似文献
560.
Zheng B Wu D Wang B Liu X Wang M Wang A Xiao G Liu P Finkelman RB 《Environmental geochemistry and health》2007,29(2):103-108
In this study, investigations into endemic fluorosis were conducted and fluorine concentration in environmental samples determined.
In an indoor coal-combustion-type fluorosis area, local clay was used to mix with coal for indoor combustion. There are two
key steps in the procedure of the indoor transition of fluorine: indoor wet corns and vegetables strongly absorbed fluorine
from indoor air; and fluorine strongly accumulated in clay, which was mixed with coal for combustion. Therefore, with the
increasing of the percentage of clay in the clay-mixed coal as well as corn in foodstuff, the ratio of fluorosis will be increased. 相似文献