首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   23172篇
  免费   1801篇
  国内免费   3947篇
安全科学   3992篇
废物处理   386篇
环保管理   3372篇
综合类   12520篇
基础理论   2524篇
环境理论   11篇
污染及防治   1941篇
评价与监测   1230篇
社会与环境   1673篇
灾害及防治   1271篇
  2024年   81篇
  2023年   391篇
  2022年   636篇
  2021年   796篇
  2020年   805篇
  2019年   674篇
  2018年   564篇
  2017年   881篇
  2016年   970篇
  2015年   1007篇
  2014年   1010篇
  2013年   1270篇
  2012年   1582篇
  2011年   1747篇
  2010年   1278篇
  2009年   1278篇
  2008年   1003篇
  2007年   1554篇
  2006年   1582篇
  2005年   1270篇
  2004年   1067篇
  2003年   1192篇
  2002年   947篇
  2001年   800篇
  2000年   727篇
  1999年   677篇
  1998年   538篇
  1997年   432篇
  1996年   370篇
  1995年   339篇
  1994年   302篇
  1993年   267篇
  1992年   202篇
  1991年   148篇
  1990年   98篇
  1989年   55篇
  1988年   48篇
  1987年   34篇
  1986年   32篇
  1985年   38篇
  1984年   21篇
  1983年   26篇
  1982年   21篇
  1981年   18篇
  1980年   23篇
  1979年   20篇
  1978年   15篇
  1977年   18篇
  1973年   14篇
  1971年   15篇
排序方式: 共有10000条查询结果,搜索用时 33 毫秒
991.
Few studies exist on how chloride from chloride‐based deicers is transported in infiltration‐based stormwater control measures. In 2009, the U.S. Environmental Protection Agency (USEPA) constructed a 0.4 ha parking lot in Edison, New Jersey, that was surfaced with permeable interlocking concrete pavers (PICP), pervious concrete (PC), and porous asphalt (PA). Each surface type has four equally sized, lined sections that direct all infiltrate to separate 5.7 m3 collection tanks. The USEPA acute criterion for aquatic life (860 mg/l) was exceeded in events immediately following a snow event. Concentrations of the infiltrate exceeded the detection limit (5 mg/l) year round but did not exceed the USEPA chronic toxicity (230 mg/l) after April. The chloride concentration decreased with cumulative rainfall since previous snow event, and a power regression described this relationship. In the power regression, the coefficient (b) described the initial concentration following a snow event, and the exponent (m) described the rate in which chloride was flushed through the system with infiltrating water. PC had the largest coefficient (5,664) and largest absolute exponent (?0.92), followed closely by PICP (= 4,943 and = ?0.87), and distantly by PA (= 2,907 and = ?0.67). The differences in release rate were proportional to the measured surface infiltration rates of 4,000; 2,400; and 200 cm/h for PC, PICP, and PA, respectively. These results will assist those who manage or regulate stormwater where receiving waters are chloride impaired.  相似文献   
992.
Microstegium vimineum is an invasive grass introduced from Asia that has spread throughout riparian areas of the eastern United States threatening native riparian vegetation. Postemergence (POST) herbicides registered for aquatic use were evaluated for control of M. vimineum on two riparian restoration sites in the Piedmont and Upper Coastal Plain of North Carolina. This study found that standard and lower than standard rates of diquat, fluridone, flumioxazin, glyphosate, imazamox, and imazapyr reduced weed stem density and biomass at 6 and 30 weeks after treatment (WAT). Both rates of bispyribac and penoxsulam provided less control of M. vimineum. Visual ratings showed both rates of diquat, flumioxazin, imazamox, and imazapyr controlled 63‐100% of M. vimineum at 6 WAT and 84‐100% at 30 WAT. Fluridone and glyphosate provided slightly less control. Bispyribac and penoxsulam treatments provided less control at 6 and 30 WAT compared to the other treatments. Plots treated with both rates of diquat, flumioxazin, imazamox, and imazapyr were nearly devoid of all vegetation at 30 WAT. Recommendations include POST application of lower than standard rates of diquat, flumioxazin, fluridone, glyphosate, imazamox, and imazapyr on riparian restoration sites infested with M. vimineum. Immediate vegetation management measures including temporary and permanent plant cover should be employed on treated sites where weeds are completely eradicated to prevent erosion.  相似文献   
993.
Hong Kong is a compact and ‘land-hungry’ city where recycling has become an important measure for treating waste and reducing the demand on the limited landfills. The objectives of this paper are to extend the model of recycling attitude and behaviour to explain the relationship between perceived policy effectiveness and recycling behaviour. Previous studies on recycling attitude and behaviour had widely adopted the theory of planned behaviour (TPB) and the norm activation model (NAM), and drawn policy implications from them. Nevertheless, little research has been conducted to investigate the role of perceived effectiveness of policy measures in predicting recycling behaviour. To address this, a model that integrates the TPB and NAM was proposed in this study, and a street survey was conducted to investigate the case. The results illustrate that recycling intention is influenced by subjective norms, perceived behavioural control, moral norms, and awareness of consequences, as well as a newly proposed construct, namely perceived policy effectiveness. The study proved self-reported recycling behaviour (direct behaviour) and support for policy measures (indirect behaviour) are influenced by recycling intention. All in all the Government should provide more recycling bins, guidelines on recycling activities, and should accent what it has been doing to facilitate and encourage recycling.  相似文献   
994.
This study proposes an improved integrated water resource management (IWRM), in which water conservation was analyzed for the entire water use process. A multi-objective optimization method was applied to optimize the IWRM, which investigated the reduction of freshwater consumption and the total water supply cost. Customer's preference for saving water and an end use analysis (EUA) was applied in the water conservation analysis. Taking Tianjin as the study area, a reduction in customer's economic pressure (EP) was utilized to evaluate the degree of the customer's preference for saving water. The results revealed that agriculture had a greater preference for saving water than other sectors, where as the public had the weakest motivation for saving water. Improving the transportation method could contribute 62.1% of the total water savings in the agriculture sector. The optimization of the IWRM demonstrated that the local freshwater savings would be 21.5%, and the total cost for water supplies would decrease by 13%. However, a government subsidy of 87.5 million Yuan would be needed. Additionally, by analyzing the change in the amount of water savings affected by water price, the appropriate water price increase range was suggested to be 1.5–1.7 times the original price.  相似文献   
995.
提出一种新纳米零价铁反应器(Nanoscale Zero-Valent Iron Reactor,简称NIR)及"混凝沉淀+纳米零价铁"处理工艺,通过实际生产废水进行中试,考察和研究该工艺和NIR技术处理江苏省某市印刷电路板(Printed Circuit Board,简称PCB)工业园区废水的效果。结果表明,此工艺对PCB生产废水中Cu、TP及COD Cr去除率分别可达到97.3%、73.7%、26%,其中Cu处理效果最佳;XRD结果表明,纳米零价铁(Nanoscale Zero-Valent Iron,nZVI)与PCB生产废水反应后含有γ-Fe2O3、Fe3O4、γ-FeOOH、CuO、Cu2O、Cu0等产物。"混凝沉淀+纳米零价铁"工艺处理废水时具有处理效果好、工艺耐冲击性能好、产泥量小、不易造成二次污染等优点。  相似文献   
996.
通过新增工业产值、农用地面积、降雨强度和环保投资4个指标,引入信息熵对各指标进行权重分配,科学界定基尼系数合理性范围,构建了以改良基尼系数为度量标准的二氧化硫总量控制方案分配合理性的评价体系,并将其应用于"十二五"西部地区二氧化硫排放总量控制规划方案合理性评价工作中。研究结果表明,西部地区"十二五"SO2总量控制方案存在不合理,可优先考虑针对环保投资进行调整。  相似文献   
997.
农村畜禽养殖污染的综合防治   总被引:1,自引:0,他引:1  
张晓燕 《四川环境》2014,(2):98-102
畜禽养殖污染已成为农村环境污染的突出问题。本文通过调查分析广安市辖区内畜禽养殖业的发展和污染现状,在实地研究广安市两个畜禽养殖示范工程的基础上,借鉴现有的畜禽养殖污染防治技术成果,提出了一套以"养殖—沼气—农灌"和"养殖—堆肥—沼气—农灌"两种模式为技术基础,结合政策和法律措施,系统防治畜禽养殖污染的方案,有助于指导农村畜禽养殖的科学、绿色发展。  相似文献   
998.
解江  郭琦  高军 《环境技术》2014,(2):20-25
作为装备贮存可靠性与贮存寿命评价的关键技术,加速寿命试验和加速退化试验已在工程中广泛应用,基于物理分析的贮存寿命特征检测技术也逐步在贮存寿命评价工程中开展。贮存寿命评价技术已有一套完整的理论基础并积累了大量的工程实践经验,但行业内至今仍缺少专门针对贮存寿命评价的软件工具。本文通过对贮存寿命评价工具箱的需求分析研究工作,构建了工具箱的技术框架,并给出工具箱各主要模块的业务流程图和业务概念图,为贮存寿命工具箱的开发提供了支撑。  相似文献   
999.
韩彬 《环境技术》2014,(2):65-67
本文以标准GB/T 29309-2012为基础,以某款开关电源为例,对HALT试验设备、工作极限与破坏极限、试验步骤及设备运行中注意点等方面展开介绍,为电子产品可靠性测试提供相关探讨。  相似文献   
1000.
热带海洋环境条件对印制电路板性能参数的影响分析   总被引:3,自引:0,他引:3  
袁敏  邹凡  王忠 《环境技术》2014,(3):21-23
分析了热带海洋环境条件对印制电路板影响的主要敏感电气参数,采用典型印制电路板工艺样件开展了西沙自然大气暴露试验,根据试验结果,对敏感参数的变化规律进行了分析。  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号