全文获取类型
收费全文 | 3035篇 |
免费 | 359篇 |
国内免费 | 929篇 |
专业分类
安全科学 | 480篇 |
废物处理 | 100篇 |
环保管理 | 217篇 |
综合类 | 2531篇 |
基础理论 | 375篇 |
污染及防治 | 312篇 |
评价与监测 | 254篇 |
社会与环境 | 32篇 |
灾害及防治 | 22篇 |
出版年
2024年 | 44篇 |
2023年 | 106篇 |
2022年 | 156篇 |
2021年 | 186篇 |
2020年 | 154篇 |
2019年 | 155篇 |
2018年 | 115篇 |
2017年 | 117篇 |
2016年 | 125篇 |
2015年 | 156篇 |
2014年 | 334篇 |
2013年 | 219篇 |
2012年 | 197篇 |
2011年 | 241篇 |
2010年 | 168篇 |
2009年 | 182篇 |
2008年 | 199篇 |
2007年 | 219篇 |
2006年 | 166篇 |
2005年 | 156篇 |
2004年 | 109篇 |
2003年 | 98篇 |
2002年 | 77篇 |
2001年 | 75篇 |
2000年 | 57篇 |
1999年 | 51篇 |
1998年 | 70篇 |
1997年 | 60篇 |
1996年 | 61篇 |
1995年 | 47篇 |
1994年 | 46篇 |
1993年 | 36篇 |
1992年 | 39篇 |
1991年 | 35篇 |
1990年 | 40篇 |
1989年 | 25篇 |
1988年 | 1篇 |
1987年 | 1篇 |
排序方式: 共有4323条查询结果,搜索用时 296 毫秒
241.
242.
243.
通风条件下甲醛浓度的检测和预测模型的建立 总被引:1,自引:0,他引:1
随着室内装修日益普遍和高档化,甲醛污染越来越严重,通风成为公认的保障人体舒适度和提高室内空气品质的可行性控制方法.在过渡季节进行通风实验,比较不同风世时甲醛浓度的降低效果及其变化规律.将甲醛浓度变化趋势分为两个主要阶段(速降阶段和渐变阶段),从而确定了同时满足卫生及节能要求的最佳换气次数(ACH)为1.5 h-1.并且建立了不同ACH条件下甲醛浓度的预测模型. 相似文献
244.
"矿井工作"的德语说法字面意思是"不见天日的工作"。在今天的德国煤矿行业里,工人们仍旧沿用以前的打招呼的方式:"祝你平安出井"。从遗留下来的这些词句可以判断,以前的德国矿井工作同样是危险行业,但是今天,"祝你平安出井"可以单纯地被当作打招呼的方式了。在德国北部伊本布伦煤矿里,《国际先驱导报》记者进行了 相似文献
245.
不久前,挪威能源集团成功地开发出海洋渗透能。研究人员在水箱的一边装上盐水,另外一边装的是淡水。中间用单向渗透薄膜隔开。由于两边的水所含的盐分不同,淡水要流到另外一边盐水浓度高的水箱,这一过程中所产生的海水渗透压力可用来发电。挪威能源集团计划投产1300万欧元,在江河入海口建一个海洋渗透能发电厂进行试验。这种新能源十分环保,不排放CO2,没有垃圾产生,不受天气状况的影响,是一种取之不尽、用之不竭的绿色能源。 相似文献
246.
Sludge concentration dynamic distribution and its impact on the performance of UNITANK 总被引:2,自引:0,他引:2
UNITANK is a biological wastewater treatment process that combines the advantages of traditional activated sludge process and sequencing batch reactor, which is divided into Tank A, B and C. In this study, the sludge distribution and its impact on performance of UNITANK were carried out in Liede Wastewater Plant (WWTP) of Guangzhou, China. Results showed that there was a strong affiliation between Tank A and B of the system in sludge concentration distribution. The initial sludge concentration in Tank A could present the sludge distribution of the whole system. The sludge distribution was mainly influenced by hydraulic condition. Unsteady sludge distribution had an impact on variations of substrates in reactors, especially in decisive reactor, and this could lead to failure of system. Settler could partially remove substrates such as COD and NO3-N, but there was adventure of sludge deterioration. The rational initial sludge concentration in Tank A should be 4000-6000 mg/L MLSS. 相似文献
247.
Bottled water may not be safer, or healthier, than tap water. The present studies have proved that styrene and some other aromatic compounds leach continuously from polystyrene (PS) bottles used locally for packaging. Water sapmles in contact with PS were extracted by a preconcentration technique called as "purge and trap" and analysed by gas chromatograph-mass spectrometer (GC/MS). Eleven aromatic compounds were identified in these studies. Maximum concentration of styrene in PS bottles was 29.5 μg/L. Apart from styrene, ethyl benzene, toluene and benzene were also quantified but their concentrations were much less than WHO guide line values. All other compounds were in traces. Quality of plastic and storage time were the major factor in leaching of styrene. Concentration of styrene was increased to 69.53 μg/L after one-year storage. In Styrofoam and PS cups studies, hot water was found to be contaminated with styrene and other aromatic compounds. It was observed that temperature played a major role in the leaching of styrene monomer from Styrofoam cups. Paper cups were found to be safe for hot drinks. 相似文献
248.
Akira KONDO Esrom HAMONANGAN Satoshi SODA Akikazu KAGA Yoshio INOUE Masaharu EGUCHI Yuta YASAKA 《环境科学学报(英文版)》2007,19(6):709-713
Total suspended particulate mater (TSP) concentrations were monitored for one year from July 2000 and for one year from April 2003 in Jakarta City. Thirteen elemental TSP components, aluminum (Al), sodium (Na), iron (Fe), lead (Pb), potassium (K), zinc (Zn), titanium (Ti), manganese (Mn), bromine (Br), copper (Cu), chromium (Cr), nickel (Ni), and vanadium (V) were analyzed by a sequential X-ray fluorescence spectrometer. Al, Na, Fe, K, and Pb were major components at most of the sampling locations in 2000. However, only Pb in 2003 dramatically decreased to one tenth. The phase-out of leaded gasoline began on July 1, 2001 in Jakarta City and lead content in gasoline decreased to one tenth, too. The decrease in Pb concentration was a result of the phase-out of leaded gasoline, as lead emissions mainly are exhaust gas from vehicles. 相似文献
249.
近年来,长三角地区灰霾天气持续增多,空气细颗粒物污染问题日益突出。基于2013年1月至2015年5月长三角地区及周边缓冲区内共214个空气质量监测站点PM2.5逐时监测数据,运用普通克里金插值方法,从年、季、月尺度上分析了PM2.5的空间分布格局和时间动态变化。结果表明:(1)2 a来,长三角地区PM2.5浓度空间分布明显呈现整体北部高南部低,局部地区略有突出的分布特征;长三角地区PM2.5浓度年均值为57.08μg/m3;其中,江苏省PM2.5的年均值为三省市最高,为65.84μg/m3;其次为上海市,年均值为53.87μg/m3;浙江省PM2.5的年均值较小,为51.53μg/m3。(2)从季节尺度分析,长三角地区PM2.5浓度变化表现出冬春季高,夏秋季低的变化趋势;这与区域内冬季风向来源、降水稀少、气象扩散条件差有着密切的关系; (3)长三角地区月浓度变化大致呈U形分布; 12月份PM2.5浓度最高; 3月份以后, PM2.5浓度开始呈逐步下降趋势;在5~9月份,区域PM2.5处于"U"字的谷底,其中6月份夏收时期秸秆焚烧、气象等因素导致PM2.5浓度有略微升高;进入10月份后迅速攀升,且11、12月份呈现持续升高态势。 相似文献
250.
Profile of Methane Concentrations in Soil and Atmosphere in Alpine Steppe Ecosystem on Tibetan Plateau 总被引:1,自引:1,他引:0
Pei Zhiyong Ouyang Hua Zhou Caiping Xu Xingliang . The Administrative Center for China’s Agenda Beijing China . Interntional Center for Integrated Mountain Development Kathm a Nepal . Institute of Geographical Sciences Natural Resources Research CAS Beijing 《中国人口.资源与环境(英文版)》2009,7(1):3-10
The methane concentration profile from -1.5m depth in soil to 32m height in air was measured in alpine steppe located in the permafrost area. Methane concentrations showed widely variations both in air and in soil during the study period. The mean concentrations in atmosphere were all higher than those in soil, and the highest methane concentration was found in air at the height of 16m with the lowest concentration occurring at the depth of 1.5m in soil. The variations of atmospheric methane concentrations did not show any clear pattern both temporally and spatially, although they exhibited a more steadystable state than those in soil. During the seasonal variations, the methane concentrations at different depths in soil were significantly correlated (R^2〉0.6) with each other comparing to the weak correlations (R^2〈0.2) between the atmospheric concentra- tions at different heights. Mean methane concentrations in soil significantly decreased with depth. This was the compositive influence of the decreasing production rates and the increasing methane oxidation rates, which was caused by the descent soil moisture with depth. Although the methane concentrations at all depths varied widely during the growing season, they showed very distinct temporal variations in the non-growing season. It was indicated from the literatures that methane oxidation rates were positively correlated with soil temperature. The higher methane concentrations in soil during the winter were determined by the lower methane oxidation rates with decreasing soil temperatures, whereas methane production rates had no reaction to the lower temperature. Relations between methane contribution and other environmental factors were not discussed in this paper for lacking of data, which impulse us to carry out further and more detailed studies in this unique area. 相似文献