全文获取类型
收费全文 | 809篇 |
免费 | 60篇 |
国内免费 | 210篇 |
专业分类
安全科学 | 207篇 |
废物处理 | 19篇 |
环保管理 | 107篇 |
综合类 | 420篇 |
基础理论 | 98篇 |
污染及防治 | 96篇 |
评价与监测 | 41篇 |
社会与环境 | 54篇 |
灾害及防治 | 37篇 |
出版年
2024年 | 4篇 |
2023年 | 23篇 |
2022年 | 32篇 |
2021年 | 30篇 |
2020年 | 35篇 |
2019年 | 36篇 |
2018年 | 26篇 |
2017年 | 47篇 |
2016年 | 45篇 |
2015年 | 71篇 |
2014年 | 36篇 |
2013年 | 68篇 |
2012年 | 80篇 |
2011年 | 52篇 |
2010年 | 39篇 |
2009年 | 46篇 |
2008年 | 40篇 |
2007年 | 62篇 |
2006年 | 33篇 |
2005年 | 50篇 |
2004年 | 37篇 |
2003年 | 35篇 |
2002年 | 27篇 |
2001年 | 12篇 |
2000年 | 12篇 |
1999年 | 20篇 |
1998年 | 11篇 |
1997年 | 9篇 |
1996年 | 9篇 |
1995年 | 8篇 |
1994年 | 10篇 |
1993年 | 11篇 |
1992年 | 4篇 |
1991年 | 1篇 |
1990年 | 6篇 |
1988年 | 1篇 |
1986年 | 1篇 |
1985年 | 1篇 |
1981年 | 1篇 |
1979年 | 2篇 |
1977年 | 2篇 |
1974年 | 2篇 |
1972年 | 1篇 |
1969年 | 1篇 |
排序方式: 共有1079条查询结果,搜索用时 15 毫秒
61.
Majagi SH Vijaykumar K Vasanthkaumar B 《Environmental monitoring and assessment》2008,138(1-3):273-279
In this study, some heavy metals concentrations (Zn, Pb, Fe, Mn, Cu, Ni) and other physico-chemical parameters were studied
during October 2001 to September 2003 in Karanja reservoir, Bidar district. Water quality parameters were collected monthly
basis whereas heavy metals were analyzed by Atomic Adsorption Spectrometer (AAS). Heavy metals have shown within the permissible
limits, except Fe and Ni were recorded higher values in southwest monsoon, where as Mn has showed higher concentration in
northeast monsoon in and summer. All other physico-chemical parameters are with in the permissible limit. Water is moderately
hard and reservoir is productive. 相似文献
62.
V. Vađić J. Hršak N. Kalinić M. Čačković K. Šega 《Environmental monitoring and assessment》2000,65(1-2):147-153
Hydrogen sulphide, ammonia, nitrogen dioxide, mercaptans and sulphur dioxide (H2S, NH3, NO2, R-SH, SO2) concentrations were measured at the location in the vicinity of the waste dump to determine the air pollution level of these pollutants prior to the operation of the Mobile Thermal Treatment Plant. Samples were collected over one year period. Seasonal differences, and the influence of meteorological parameters (temperature, relative humidity, pressure and wind direction) on the air pollution levels were studied. Results show relatively low concentrations of H2S, NO2, R-SH and SO2, while NH3 levels were higher compared to the guideline values. Good weather conditions (high air pressure and low relative humidity) are connected to long range transport of NO2, while higher temperatures result in elevated NH3 and R-SH concentrations. Because of the predominant northeast wind direction (the same as the waste dump direction), the contribution of air pollution from the direction of the waste dump at the measuring site is significant, but that does not necessarily mean that the pollutants originated from that source. 相似文献
63.
We examined the influence of several hydrological and meteorological parameters on the migratory movements of ayu Plecoglossus altivelis altivelis in central Japan. When comprehensively evaluating rivers and ayu behaviour on a catchment scale, the subjects of analysis typically include human activities and hydrological and meteorological phenomena. However, limiting analyses to such factors may be too restrictive when human activities are being conducted. Accordingly, we incorporated a biological viewpoint into the evaluation method, analysing hydrological data (river discharge, river water temperature, sea water temperature) to determine watershed characteristics and examining the relationship between these characteristics and the habitat conditions of ayu. Then we constructed a numerical model for ayu migratory runs that incorporated ayu ecology and watershed characteristics. Analyses of ayu movements from a lower estuarine dam demonstrated that downstream displacements were associated with high water flows of more than 200 m3 s−1 at the beginning of summer. We conclude that it is important to consider the effects of environmental parameters on the movements of different fish species to understand the causes of spatial variation in fish distribution in lowland rivers. 相似文献
64.
Gerald Kirchner Friederike Strebl Peter Bossew Sabine Ehlken Martin H. Gerzabek 《Journal of environmental radioactivity》2009
Literature data on numerical values obtained for the parameters of the two most popular models for simulating the migration of radionuclides in undisturbed soils have been compiled and evaluated statistically. Due to restrictions on the applicability of compartmental models, the convection–dispersion equation and its parameter values should be preferred. For radiocaesium, recommended values are derived for its effective convection velocity and dispersion coefficient. Data deficiencies still exist for radionuclides other than caesium and for soils of non-temperate environments. 相似文献
65.
The biochemical and toxicological significance of cesium is scarcely understood, and could be evaluated in comparison with lithium widely used as a psychotropic drug. Two male Wistar rat groups of 200–220 g are administered independently, lithium, sodium, rubidium and cesium chloride, in doses of 3mEq/Kg/day (0.024 Eq/L drinking water) during 29 days. Motor activity was measured after the injection of 70 mg pargyline/Kg animal i.p. as inhibitor of MAO A + B with an activimeter of Tedeschy type. Accumulative movements per minute are presented in function of time. Total brain proteins, alkaline and acid phosphatases and blood parameters, haematocrit, haemoglobin and erythrocytes, were determined. The maximal increase of motor activity was seen in rats treated with RbCl 2 h after the pargyline administration and the diminution was Rb>Li>Cs. Cesium induced a decrease of the total serum protein concentration from 6.39 ± 0.1 to 5.8±0.5mg/100ml serum in controls. Acid and alkaline phosphatase were decreased in cesium treated rats. The three determined blood parameters, haematocrit, haemoglobin and erythrocytes, show also a decrement with cesium treatment compared to the control ones. 相似文献
66.
Y. Dubuc P. Janneteau R. Labont C. Roy F. Brire 《Journal of the American Water Resources Association》1986,22(2):297-303
ABSTRACT: The use of peatlands as the main form of wastewater treatment in a northern climate was studied for the James Bay Energy Society. The Fontanges campsite (70° 17′ 30″ W; 54° 34′ 00″ N) was chosen as the study site. In less than 1.5 km from the point of discharge BOD5, COD, total hardness, inorganic carbon, orthophosphates, total phosphorus, ammonia and total nitrogen were reduced by at least 90 percent. The peatland treatment system studied is divided into four components, each having a specific function. The first part combines the action of microorganisms and adsorption on peat, thus reducing the organic content while increasing the inorganic constituents. The second part uses peat to adsorb the inorganic elements already present in the wastewater and those produced in the first part of the system. The third component acts as an aerator, increasing the dissolved oxygen and decreasing the BOD5 levels of the water. The fourth part removes most of the remaining nutrients, thus acting like a tertiary treatment. Overall, peatlands seemed to be effective in treating domestic settled wastewater in a cold climate. 相似文献
67.
Four satellites have been used in meteorology. They are TIROS, ESSA, Nimbus, and Applications Technology Satellite (ATS). The first three operate in the orbital altitudes of about 1000 to 1200 km while the fourth, ATS, is at geosynchronous altitude of 36,000 km. Cloud cover is being observed operationally from low orbit and experimentally from synchronous altitude. Wind velocity has been inferred from the frequent cloud cover pictures taken by ATS and satellite-balloon systems are being developed which will locate and track constant-density level balloons for determining wind flow. Spectrometers and radiometers operating in the electromagnetic spectral region from the ultraviolet to the microwave region are being developed to quantitatively measure temperature, water vapor, density, and wind profiles. These will furnish data for the development and testing of atmospheric models for numerical prediction. In addition, experiments are being developed to measure ozone and other constituents of the air, solar energy, surface conditions, heat balance and other atmospheric attributes which affect the structure and dynamics of the atmosphere. 相似文献
68.
自然灾害综合区划的基本类别及定量方法 总被引:11,自引:2,他引:9
依据区域灾害系统论原理,提出了以灾害强度、灾害势、抗灾力和灾度4个状态参量描述的区域自然灾害系统状态,建议以之为基础,将自然灾害综合区划分为灾害强度区划、灾害势区划、抗灾力区划和灾度我划4个基本类别、并结合自然灾害综合区划定量方法的讨论,以实例说明了上述基本类别类别划分的可行性。 相似文献
69.
皖南山区是我国著名的南方亚热带丘陵山地的重要组成部分。从自然生态环境、社会经济条件、发展基础、科技支撑、发展资金等方面对本区特色农业发展条件进行了深入分析,并指出了皖南山区特色农业的发展必须坚持以市场为导向、发挥比较优势、依靠科技进步、尊重农民意愿、可持续发展的原则,以及皖南山区特色农业的发展重点是茶叶、蚕桑、干鲜果、中药材、蜂产品等的生产与基地建设。从合理布局与科学规划、开拓资金来源渠道、培育和完善市场体系、科技兴农、建立特色农产品原产地保护制度和进行组织创新等方面提出了皖南山区特色农业发展的对策。 相似文献
70.
针对学生提出的英语写作难这一问题进行了专项调查,发现他们在实践写作中存在语篇、语用、语义等较深层次的错误和句子结构、语法层次、汉式表达等基础层次的错误。因而,从师与生、教与学两个角度提出了相应的建议:明确教师与学生的职责,把听、说、读、写四项基本技能融为一体。 相似文献