全文获取类型
收费全文 | 485篇 |
免费 | 22篇 |
国内免费 | 80篇 |
专业分类
安全科学 | 80篇 |
废物处理 | 11篇 |
环保管理 | 101篇 |
综合类 | 198篇 |
基础理论 | 73篇 |
环境理论 | 1篇 |
污染及防治 | 45篇 |
评价与监测 | 40篇 |
社会与环境 | 26篇 |
灾害及防治 | 12篇 |
出版年
2024年 | 1篇 |
2023年 | 11篇 |
2022年 | 10篇 |
2021年 | 7篇 |
2020年 | 8篇 |
2019年 | 14篇 |
2018年 | 12篇 |
2017年 | 13篇 |
2016年 | 21篇 |
2015年 | 22篇 |
2014年 | 18篇 |
2013年 | 27篇 |
2012年 | 34篇 |
2011年 | 35篇 |
2010年 | 22篇 |
2009年 | 32篇 |
2008年 | 31篇 |
2007年 | 41篇 |
2006年 | 32篇 |
2005年 | 23篇 |
2004年 | 19篇 |
2003年 | 22篇 |
2002年 | 15篇 |
2001年 | 10篇 |
2000年 | 15篇 |
1999年 | 10篇 |
1998年 | 15篇 |
1997年 | 5篇 |
1996年 | 4篇 |
1995年 | 7篇 |
1994年 | 3篇 |
1993年 | 3篇 |
1992年 | 4篇 |
1990年 | 1篇 |
1988年 | 5篇 |
1987年 | 1篇 |
1986年 | 2篇 |
1985年 | 1篇 |
1984年 | 7篇 |
1983年 | 2篇 |
1982年 | 3篇 |
1980年 | 1篇 |
1979年 | 3篇 |
1977年 | 5篇 |
1976年 | 1篇 |
1975年 | 1篇 |
1973年 | 2篇 |
1972年 | 1篇 |
1971年 | 5篇 |
排序方式: 共有587条查询结果,搜索用时 15 毫秒
1.
湘南地区杂柑天草高接换冠关键技术 总被引:3,自引:0,他引:3
天草杂柑的高接换冠的关键技术主要是:注意选择母树并适当修剪;合理采穗和保湿;科学嫁接;嫁接后精心管理. 相似文献
2.
YU Guang-ning ZHANG Chun-hui SU Zhong-jie FAN Xue-li PAN Yong-zhan LIU Fu-shun . Civil engineering institute Qingdao Technological University Qingdao . Engineering college Ocean University of China Qingdao . Liaoning Technical University Fuxin 《地球与环境》2005,33(Z1):17-26
<正>To control land surface subsidence caused the underground mineral exploitation and the catastrophic phenomena such as serious damage of buildings, waterbodies, cultivated lands, railways, bridges caused by land subsidence, bed separation grouting technology of overburden is put forward. To provide theoretical support for the technology, the characteristics and the mechanics mechanism of mining overburden from layer-split to formation of bed separation are studied. On the basis of elastic sheet board theory, calculation formula of rock sheet deflection is presented, and the mechanics criteria of the separation formation and the calculation formula of bed separation volume are set up. Finally, the applications and technics of bed separation grout technology of mining overburden to control land subsidence in china are introduced. 相似文献
3.
沉积物间隙水的几种制备方法 总被引:10,自引:0,他引:10
间隙水的制备对研究沉积和中物质的动力学非常重要。间隙水的制备方法有离心法、压榨法、渗析法、吸气引液法等,这些方法各有利弊。本文对这些方法分别进行了了综合比较。 相似文献
4.
简要介绍了裂变径迹定年的分析方法 ,实验技术 (包括单矿物分选、制片、抛磨、蚀刻及径迹测量技术 )的研究现状、存在的问题及发展趋势 相似文献
5.
半导体生产排放的废气和废水中砷、磷、硫的分析方法研究 总被引:2,自引:0,他引:2
研究了一种快速、灵敏、可靠的高温氢还原-气相色谱分析方法[1-2],并自行设计了高温还原系统(还原炉、六通阀等),测定半导体生产排放废气和废水中的砷、磷、硫及其化合物,样品不需预处理,使气相色谱仪能直接测定固、液、气相样品中砷、磷、硫及其化合物的含量。砷、磷、硫的检测限分别为0.01mg/L、0.003mg/L、0.02mg/L;相对标准偏差分别为6.2%、8.6%和0.3%,与经典方法进行对比,结果基本一致。从分析方法的误差统计角度,也说明该方法准确、可靠。 相似文献
6.
乌达煤矿采空区煤自燃影响因素评价分析 总被引:2,自引:3,他引:2
应用层次分析理论,选择影响乌达煤矿采空区煤自然发火的主要因素即煤的自燃倾向性、煤层的赋存条件、开采技术水平等,进行分析计算。依据层次分析法确定了采空区煤自燃各影响因素的权重系数,并对其进行总排序,最后进行综合评定各采空区煤自燃影响因素。评定结果表明:煤自燃倾向性M、煤的硫含量L、回采工作面推进速度g、地质构造d等是影响采空区煤自燃的主要因素。为制定相应的开拓开采方案和有效的防火措施,提供了科学的理论依据和切合实际情况的评价方法。 相似文献
7.
For more than 30 years, multiple research groups have worked on the automation of hazard and operability (HAZOP) studies, or more specifically on the hazard identification process. So far, very few of these approaches have been used in the chemical process industry. Automatic hazard identification is a knowledge-intensive process that demands high standards with regard to the way in which knowledge is stored and made available. There are various suitable approaches to the qualitative modeling of processes and plants, which are the foundation for reasoning systems that are used for the identification of hazards. Additionally, there are quantitative methods that are based on process simulations and can be used to identify potential hazards. The investigation of the state of research demonstrates that there are sophisticated technologies for automated systems that include powerful reasoning techniques. The benefits and shortcomings of existing technologies are discussed with regard to their industrial applicability. Often, the quality of the necessary specific and generic knowledge is not sufficient to detect potential hazardous events and operational malfunctions. Computer-aided HAZOP systems should be integrated with computer-aided design- or process simulation software using common data models based on the digital representation of the process plant. In order to be used by HAZOP practitioners automated systems need to be comprehensive, serve as specialized decision support systems, and be tested and evaluated using round robin tests. 相似文献
8.
以2014—2015年双台子河口滨海湿地植被修复20个站位调查资料为基础,对湿地修复结构指标、功能指标和环境指标进行研究,结合湿地生态系统健康理论,构建湿地生态环境健康评价指标体系。运用层次分析法(AHP)确定权重,对各个指标赋予权重,将健康评价分为3个等级,确立了生态健康评价方法,对近岸破损湿地翅碱蓬修复生境进行评价。进一步引用评价净影响值(EI)方法判断生境修复前、后的健康对比状态,从而确定翅碱蓬对该破损湿地的修复效果显著。从景观生态学和健康评价角度分析来看,建立此评价方法是可行的,可为今后湿地的管理与保护提供科学依据。 相似文献
9.
Based on previous research, the sampling and analysis methods for phthalate esters (PAEs) were improved by increasing the sampling flow of indoor air from 1 to 4 L/min, shortening the sampling duration from 8 to 2 hr. Meanwhile, through the optimization of chromatographic conditions, the concentrations of 9 additional PAE pollutants in indoor air were measured. The optimized chromatographic conditions required a similar amount of time for analysis as before, but gave high responsivity, the capability of simultaneously distinguishing 15 kinds of PAEs, and a high level of discrimination between individual sample peaks, as well as stable peak generation. The recovery rate of all gas-phase and particle-phase samples of the 15 kinds of PAEs ranged from 91.26% to 109.42%, meeting the quantitative analysis requirements for indoor and outdoor air sampling and analysis. For the first time, investigation of the concentration levels as well as characteristics of 15 kinds of PAEs in the indoor air from four different traffic micro-environments (private vehicles, busses, taxis and subways) was carried out, along with validation of the optimized sampling and analytical method. The results show that all the 9 additional PAEs could be detected at relatively high pollution levels in the indoor air from the four traffic micro-environments. As none of the pollution levels of the 15 kinds of PAEs in the indoor air from the 4 traffic micro-environments should be neglected, it is of great significance to increase the types of PAEs able to be detected in indoor air. 相似文献
10.