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   3266篇
  免费   181篇
  国内免费   831篇
安全科学   245篇
废物处理   142篇
环保管理   293篇
综合类   1562篇
基础理论   449篇
污染及防治   1016篇
评价与监测   231篇
社会与环境   228篇
灾害及防治   112篇
  2024年   7篇
  2023年   53篇
  2022年   155篇
  2021年   132篇
  2020年   110篇
  2019年   98篇
  2018年   119篇
  2017年   128篇
  2016年   129篇
  2015年   156篇
  2014年   197篇
  2013年   318篇
  2012年   223篇
  2011年   280篇
  2010年   206篇
  2009年   179篇
  2008年   193篇
  2007年   201篇
  2006年   174篇
  2005年   129篇
  2004年   115篇
  2003年   131篇
  2002年   175篇
  2001年   162篇
  2000年   107篇
  1999年   87篇
  1998年   38篇
  1997年   52篇
  1996年   34篇
  1995年   39篇
  1994年   34篇
  1993年   21篇
  1992年   26篇
  1991年   21篇
  1990年   4篇
  1989年   8篇
  1988年   6篇
  1986年   4篇
  1985年   3篇
  1984年   4篇
  1983年   3篇
  1982年   4篇
  1981年   6篇
  1980年   1篇
  1979年   2篇
  1978年   1篇
  1977年   1篇
  1973年   1篇
  1960年   1篇
排序方式: 共有4278条查询结果,搜索用时 15 毫秒
91.
论绿色押金制度   总被引:3,自引:1,他引:3  
本文从绿色押金制度的产生背景、概念特点入手,从法经济学的角度对其进行了分析,对该制度在国外的实施情况作了简要介绍,并从押金的实施范围、收费标准、管理和退还四个方面提出了在我国建立该制度的设想。  相似文献   
92.
农业气象干旱指标研究综述   总被引:16,自引:0,他引:16  
干旱作为最严重的气象灾害之一,已经对我国社会经济和人民生活造成严重影响。结合农业干旱和气象干旱基本理论,对农业气象干旱的定义及指标作了较为详细的综述与评价,指出了不同指标的优点和缺点,对今后的研究方向进行了展望,为干旱的监测和评估及农业防灾减灾研究提供了方法和依据。  相似文献   
93.
常天海  尹俊勋  黎曦  汪志成 《安全》2006,27(4):21-24
静电测试是整个静电防护工程中不可或缺的组成部分,也是静电防护设计和管理的依据.本文主要介绍了静电基本参数中的静电电位、静电电容和静电电量的测试原理,并结合具体测试数据对测试的方法和仪器进行了分析.  相似文献   
94.
中国船舶机舱火灾研究现状   总被引:16,自引:1,他引:16  
分析了船舶机舱失火的原因和机舱火灾的特点 ,对我国船舶机舱火灾的研究现状进行了综述 ,对机舱火灾的研究前景进行了展望 ,提出了机舱火灾基础研究和应用研究面临的主要课题 ,表达了船舶机舱火灾研究的重要意义。  相似文献   
95.
ABSTRACT: Surface and subsurface drainage make crop production economically viable in much of southern Minnesota because drainage allows timely field operations and protects field crops from extended periods of flooded soil conditions. However, subsurface drainage has been shown to increase nitrate/nitrogen losses to receiving waters. When engaging in drainage activities, farmers are increasingly being asked to consider, apart from the economic profit, the environmental impact of drainage. The Agricultural Drainage and Pesticide Transport model (ADAPT) was used in this study to evaluate the impact of subsurface drainage design on the soil water balance over a two‐year period during which observed drainage discharge data were available. Twelve modeling scenarios incorporated four drainage coefficients (DC), 0.64 cm/d, 0.95 cm/d, 1.27 cm/d, and 1.91 cm/d, and three drain depths, 0.84 m, 1.15 m, and 1.45 m. The baseline condition corresponded to the drainage system specifications at the field site: a drain depth and spacing of 1.45 m and 28 m, respectively (DC of 0.64 cm/d). The results of the two‐year simulation suggested that for a given drainage coefficient, soils with the shallower drains (but equal DC) generally have less subsurface drainage and can produce more runoff (but reduced total discharge) and evapotranspiration. The results also suggested that it may be possible to design for both water/nitrate/nitrogen reduction and crop water needs.  相似文献   
96.
抗污染的树   总被引:1,自引:0,他引:1  
赵叶 《防灾博览》2005,(3):26-26
许多植物在千百万年漫长进化演变过程中,炼就了非凡的绝招。它们对钾、铅、硫、氯、硒、锶、铠等化学元素有着神奇的解毒功能,并能从水、空气、土壤中吸收有害的污染物质,自行消化排解。  相似文献   
97.
在一体式一膜生物反应器处理生活污水的基础上,考察了运行过程中膜污染情况。试验结果表明,膜外表面沉积污泥是造成膜污染的主要因素,在活性污泥混合液中搓洗膜丝,是一种方便而有效的清洗方式。间歇式运行方式的停抽期间最低剩余抽吸压力可用来表征运行过程中膜过滤性能的变化。  相似文献   
98.
The performance of a wetland system in treating lead (Pb)/zinc (Zn) mine drainage was evaluated by using the polyurethane foam unit (PFU) microbial community (method), which has been adopted by China as a standardized procedure for monitoring water quality. The wetland system consisted of four cells with three dominant plants: Typha latifolia, Phragmites australis and Paspalum distichum. Physicochemical characteristics [pH, EC, content of total suspended solid (TSS) and metals (Pb, Zn, Cd, and Cu)] and PFU microbial community in water samples had been investigated from seven sampling sites. The results indicated that the concentrations of Pb, Zn, Cd, Cu, and TSS in the mine drainage were gradually reduced from the inlet to the outlet of the wetland system and 99%, 98%, 75%, 83%, and 68% of these metals and TSS respectively, had been reduced in concentration after the drainage passed through the wetland system. A total of 105 protozoan species were identified, the number of protozoa species and the diversity index (DI) gradually increased, while the heterotrophic index (HI) gradually decreased from the inlet to the outlet of the wetland system. The results indicated that DI, HI, and total number species of protozoa could be used as biological indicators indicating the improvement of water quality.  相似文献   
99.
There are growing interests to use co-composted drilling wastes contaminated with hydrocarbons as growth media for planting in land reclamation. However, such use of the compost may have potential problems such as inherent toxicity of residual hydrocarbon and microbial N immobilization due to high compost C to N ratios. We investigated the growth, biomass production, N uptake, and foliar delta13C of white spruce (Picea glauca [Moench] Voss) seedlings in a pot experiment using 1-, 2-, 3-, and 4-yr-old composts (with different hydrocarbon concentrations and C to N ratios) and a local noncontaminated soil with (200 kg N ha(-1)) or without N fertilization. Growth and N content of seedlings (particularly N content in roots) were lower when grown in the compost media as compared with those grown in the soil. Within the compost treatments seedling growth was affected by compost age, but the magnitude of growth reduction was not linearly proportional to hydrocarbon concentrations. Plant N uptake increased with compost age, which corresponds with an increase in indigenous mineral N concentration. Effects of N fertilization on N uptake were curtailed by the presence of indigenous mineral N (e.g., in the 4-yr-old compost) and by fertilization-induced stimulation of microbial activities (e.g., in the 1-yr-old compost). The differences in foliar delta13C values between seedlings grown in compost and soil (P < 0.05) suggest that limitations on water uptake caused by the residual hydrocarbon might have been the predominant factor limiting seedling growth in the compost media. This study suggests that water stress caused by residual hydrocarbons may be a critical factor for the successful use of co-composted drilling wastes as a growth medium.  相似文献   
100.
Sustainable development goals are achievable through the installation of Material Recovery Facilities (MRFs) in certain solid waste management systems, especially those in rapidly expanding multi-district urban areas. MRFs are a cost-effective alternative when curbside recycling does not demonstrate long-term success. Previous capacity planning uses mixed integer programming optimization for the urban center of the city of San Antonio, Texas to establish that a publicly owned material recovery facility is preferable to a privatized facility. As a companion study, this analysis demonstrates that a MRF alleviates economic, political, and social pressures facing solid waste management under uncertainty. It explores the impact of uncertainty in decision alternatives in an urban environmental system. From this unique angle, waste generation, incidence of recyclables in the waste stream, routing distances, recycling participation, and other planning components are taken as intervals to expand upon previous deterministic integer-programming models. The information incorporated into the optimization objectives includes economic impacts for recycling income and cost components in waste management. The constraint set consists of mass balance, capacity limitation, recycling limitation, scale economy, conditionality, and relevant screening restrictions. Due to the fragmented data set, a grey integer programming modeling approach quantifies the consequences of inexact information as it propagates through the final solutions in the optimization process. The grey algorithm screens optimal shipping patterns and an ideal MRF location and capacity. Two case settings compare MRF selection policies where optimal solutions exemplify the value of grey programming in the context of integrated solid waste management.  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