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   11064篇
  免费   1539篇
  国内免费   6174篇
安全科学   1905篇
废物处理   396篇
环保管理   1129篇
综合类   10468篇
基础理论   2026篇
环境理论   2篇
污染及防治   1471篇
评价与监测   623篇
社会与环境   526篇
灾害及防治   231篇
  2024年   75篇
  2023年   464篇
  2022年   692篇
  2021年   779篇
  2020年   755篇
  2019年   751篇
  2018年   648篇
  2017年   627篇
  2016年   720篇
  2015年   793篇
  2014年   713篇
  2013年   1165篇
  2012年   1215篇
  2011年   1297篇
  2010年   839篇
  2009年   945篇
  2008年   756篇
  2007年   887篇
  2006年   878篇
  2005年   645篇
  2004年   540篇
  2003年   466篇
  2002年   345篇
  2001年   317篇
  2000年   273篇
  1999年   226篇
  1998年   153篇
  1997年   153篇
  1996年   120篇
  1995年   120篇
  1994年   80篇
  1993年   82篇
  1992年   51篇
  1991年   23篇
  1990年   25篇
  1989年   19篇
  1988年   14篇
  1987年   5篇
  1986年   12篇
  1985年   4篇
  1984年   7篇
  1983年   11篇
  1982年   14篇
  1981年   9篇
  1980年   6篇
  1979年   4篇
  1978年   4篇
  1973年   5篇
  1972年   5篇
  1971年   34篇
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
81.
Air pollution problems in developing countries have gained larger fraction in the last decade especially due to non functioning and non implementation of effective air pollutioncontrol devices in industries. In industrial wastewater management, adequate treatability studies are conducted to arrive at a techno-economic treatment option. However no suchstudies were done for reducing air pollution or emission fromindustries until now in India. Little information was availableabout such studies in other countries. This article provides information about a novel technique known asflue gas treatability studies and to undertake such studies, a pilot scale system is installed in Air Pollution Control Divisionof M/s National Environmental Engineering research Institute, NEERI, Nagpur-20, India. This study is a tool for techno-economicselection of air pollution control systems specially for small/medium scale industrial emissions.  相似文献   
82.
Sulphur dioxide and PM10 levels are investigated in Erzurum during the periods of 1990–2000 heating season to assess air pollution level. For that reason, emissions of sulphur dioxide and particulate matter were calculated by using consumption of fuels and Turkish emission factors. These emission values were evaluated together with air pollution levels, which were measured at six stations in Erzurum atmosphere during 1990–2000 winter periods. Results reveal that in 1990–1994 heating period, there is an increasing trend in the emissions and air pollution levels over Erzurum, and the air quality limits were not met. The daily 24 h limit (short-term limit) was exceeded 127 days in 1992–1993 winter period. The reason for this increase was found to be the switching to use of low-quality fossil fuels instead of cleaner ones. Results also indicated that there was a considerable decrease in emissions of air pollutants and air pollution levels after 1995. This can be explained by the consumption of more high-quality fossil fuels. The correlation coefficient of SO2 with PM10 is obtained as r2 = 0.85, which is a high value supporting the idea that both pollutants are emitted from the same source.  相似文献   
83.
This paper presents an environmental hazard assessment to account the impacts of single rainstorm variability on river-torrential landscape identified as potentially vulnerable mainly to erosional soil degradation processes. An algorithm for the characterisation of this impact, called Erosive Hazard Index (EHI), is developed with a less expensive methodology. In EHI modelling, we assume that the river-torrential system has adapted to the natural hydrological regime, and a sudden fluctuation in this regime, especially those exceeding thresholds for an acceptable range of flexibility, may have disastrous consequences for the mountain environment. The hazard analysis links key rainstorm energy variables expressed as a single-storm erosion index (EIsto), with impact thresholds identified using an intensity pattern model. Afterwards, the conditional probabilities of exceeding these thresholds are spatially assessed using non-parametric geostatistical techinques, known as indicator kriging. The approach was applied to a test site in river-torrential landscape of the Southern Italy (Benevento province) for 13 November 1997 rainstorm event.  相似文献   
84.
The paper presents a new method of air pollution modelling on a micro scale. For estimation of concentration of car exhaust pollutants, each car is treated as an instantaneous moving emission source. This approach enables us to model time and spatial changes of emission, especially during cold and cool start of an engine. These stages of engine work are a source of significant pollution concentration in urban areas. In this work, two models are proposed: one for the estimation of emission after cold start of the engine and another for the prediction of pollutant concentration. The first model (defined for individual exhaust gas pollutants) enables us to calculate the emission as a function of time after the cold or cool start, ambient temperature and average speed of motion. This model uses the HBEFA database. The second mathematical model is developed in order to calculate the pollutant dispersion and concentrations. The finite volume method is applied to discretise the set of partial differential equations describing wind flow and pollutant dispersion in the domain considered. Models presented in this paper can be called short-term models on a small spatial scale. The results of numerical simulation of pollutant emission and dispersion are also presented.  相似文献   
85.
1985年~1989年由新疆、甘肃、青海、西藏、内蒙古、陕西、宁夏等省、自治区环境监测站(研究所)对内陆流域各类水体中U、Th、~(226)Ra、~(40)K浓度进行调查,由调查的29条内陆河、23个湖泊、15座水库、55处井泉和34个自来水的统计结果表明,流域内各水体中U和~(40)K浓度的平均值与同期调查的黄河水系同类水体的浓度相近,明显高于长江水系,与全国同类水体相比亦属偏高。Th和~(226)Ra的平均浓度与全国同类水体的浓度相近,甘、新内陆区浓度较低。调查发现,一些咸水湖、井水和自来水中U、~(226)Ra,或~(40)K浓度异常偏高。  相似文献   
86.
Sequential extraction of metals from solid media is a common analytical tool used in environmental and exploration geochemistry. A number of procedures exist, but without harmonization and standardization, meaningful comparisons are tenuous without baseline data. A newly developed, standardized sequential extraction procedure (optimized BCR) was applied to two contaminated certified reference soils from Montana, US (SRM 2710 and SRM 2711) for Cu, Pb and Zn. Four operationally defined fractions were isolated, acid extractable, reducible, oxidizable, and residual (by aqua regia). Fraction-specific concentrations, percentages and recoveries for Cu, Pb and Zn were used to explore differences between the optimized BCR procedure and three other sequential extraction schemes with published data for SRM 2710 and 2711 (i.e. Tessier scheme, Geological Survey of Canada scheme and the original BCR scheme). Results indicate significant differences between the four schemes, even for schemes that are closely associated (i.e. the original and optimized BCR schemes). Order-of-magnitude fraction-specific concentration differences were observed, especially for Pb in the reducible fraction. Differences between schemes are worrisome because trends varied between metals, between fractions and between reference soils. These data reinforce the need for increased adoption of standardized sequential extraction procedures and further examination of different solid media.  相似文献   
87.
三维虚拟地理环境构建与应用   总被引:2,自引:0,他引:2  
可量测三维虚拟地理环境是数字地球应用的基础平台。本文研究了三维虚拟地理环境构建空间几何建模与纹理建模关键技术。提出了一种适用于大规模生产建库的可量测三维虚拟地理环境构建的生产工艺模型和三维虚拟模型数据获取的方法。介绍了三维虚拟地理环境在城市规划、房产经营管理等方面的应用。  相似文献   
88.
分光光度法测定雨水中微量过氧化氢的研究   总被引:1,自引:0,他引:1  
本文提出了以钛(IV) 过氧化氢 2 (3,5 二溴 2 吡啶偶氮) 5 二乙氨基苯酚(3,5 diBr PADAP)三元配合物体系光度测定雨水中微量过氧化氢的方法,该方法简便,灵敏度和选择性较高,所得结果令人满意  相似文献   
89.
Catalytic wet air oxidation (CWAO) is one of the most promising technologies for pollution abatement. Developing catalysts with high activity and stability is crucial for the application of the CWAO process. The Mn/Ce complex oxide catalysts for CWAO of high concentration phenol-containing wastewater were prepared by coprecipitation. The catalyst preparation conditions were optimized by using an orthogonal layout method and single-factor experimental analysis. The Mn/Ce serial catalysts were characterized by Brunauer-Emmett-Teller (BET) analysis and the metal cation leaching was measured by inductively coupled plasma torch-atomic emission spectrometry (ICP-AES). The results show that the catalysts have high catalytic activities even at a low temperature (80°C) and low oxygen partial pressure (0.5 MPa) in a batch reactor. The metallic ion leaching is comparatively low (Mn<6.577 mg/L and Ce<0.6910 mg/L, respectively) in the CWAO process. The phenol, CODCr, and TOC removal efficiencies in the solution exceed 98.5% using the optimal catalyst (named CSP). The new catalyst would have a promising application in CWAO treatment of high concentration organic wastewater. Translated from Techniques and Equipment for Environmental Pollution Control, 2005, 6(2): 40–44 [译自: 环境污染治理技术与设备]  相似文献   
90.
对多环芳烃(PAHS)4种理化参数(K;W、Sw。X Vv。)与 LCO的相关关系进行了研究,建立了 4种一元线性回归方程。结果表明,4种参数的相关系数分别为:0.刀66、08083、09488、0.9570,经r检验,后两种属高度显著相关.用所建立的一元线性回归方程对7种PAHS的LC。进行估算,估算值与实测值相比,平均相对误差分别为58.84%、32.23%、1761%、198%,用l和V*.H对LClj进行估算的估算精度也较高。经比较,提出用(。估算P*比对麦穗鱼*CO的新方法。  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