全文获取类型
收费全文 | 12413篇 |
免费 | 494篇 |
国内免费 | 4459篇 |
专业分类
安全科学 | 828篇 |
废物处理 | 799篇 |
环保管理 | 932篇 |
综合类 | 6875篇 |
基础理论 | 2040篇 |
环境理论 | 6篇 |
污染及防治 | 4419篇 |
评价与监测 | 470篇 |
社会与环境 | 433篇 |
灾害及防治 | 564篇 |
出版年
2024年 | 1篇 |
2023年 | 197篇 |
2022年 | 586篇 |
2021年 | 483篇 |
2020年 | 356篇 |
2019年 | 363篇 |
2018年 | 484篇 |
2017年 | 560篇 |
2016年 | 526篇 |
2015年 | 703篇 |
2014年 | 970篇 |
2013年 | 1274篇 |
2012年 | 1022篇 |
2011年 | 1192篇 |
2010年 | 858篇 |
2009年 | 848篇 |
2008年 | 889篇 |
2007年 | 697篇 |
2006年 | 659篇 |
2005年 | 483篇 |
2004年 | 352篇 |
2003年 | 437篇 |
2002年 | 383篇 |
2001年 | 314篇 |
2000年 | 342篇 |
1999年 | 400篇 |
1998年 | 329篇 |
1997年 | 312篇 |
1996年 | 295篇 |
1995年 | 262篇 |
1994年 | 178篇 |
1993年 | 156篇 |
1992年 | 114篇 |
1991年 | 94篇 |
1990年 | 64篇 |
1989年 | 54篇 |
1988年 | 44篇 |
1987年 | 19篇 |
1986年 | 22篇 |
1985年 | 11篇 |
1984年 | 11篇 |
1983年 | 10篇 |
1982年 | 10篇 |
1981年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 533 毫秒
741.
真空紫外光降解苯的研究 总被引:1,自引:0,他引:1
为了考察真空紫外光辐射在气体净化中的应用,以苯作为目标污染物,分别进行了紫外光波长、气体湿度、反应时间、初始浓度以及辐射功率对苯光解率的影响实验。实验结果表明,真空紫外光辐射方法净化气相污染物中的苯效果良好,在一定条件下,浓度为348.2 mg/m3苯污染气体真空紫外光降解率可达到90%。通过在不同条件下苯的降解率以及臭氧浓度变化,初步探讨了苯降解的机理以及降解途径。苯的降解主要是通过氢氧自由基(·OH)的加成以及后续一系列的氧化反应,降解产物为苯酚以及含有羟基的长链烃。 相似文献
742.
743.
744.
745.
在搜集西安市“城中村”现状资料的基础上,重点归纳总结了其房屋抗震设防方面存在的问题。通过简述政府对“城中村”改造建设的指导思想、规划计划、工作思路、组织领导、立项审批等,说明了改造建设后新区的房屋抗震设防情况,并对新区的防震保安工作进行了粗浅的探讨。 相似文献
746.
747.
748.
In November 2005, an explosion occurred at a petrochemical plant of the Jilin Petrochemical Corporation in Jilin Province, China. A nearby water body was seriously polluted with a large spill of toxic substances made up of a mixture of benzene, aniline, and nitrobenzene (NB). To understand the long term impact of NB on public health and ecosystem around the Songhua River, it was necessary to investigate its fate in the environment. In this study, a microcosm was used to mimic the polluted water system and to study the transport and fate of NB in the river water body. The volatility and biodegradation of NB was investigated and a Markov model was applied to predict the fate of NB in the environment. The simulated results matched very well with the results obtained from the microcosm experiment. The model indicated that at room temperature and after around 500 h, there was only residual NB in the water and sediment. Most of the NB (around 82%) evaporated into the air and 18% was degraded by microorganisms. 相似文献
749.
Yao Z Wang Q He K Huo H Ma Y Zhang Q 《Journal of the Air & Waste Management Association (1995)》2007,57(11):1379-1386
On-board emission measurements were performed on 49 light-duty gasoline vehicles in seven cities of China. Vehicle-specific power mode distribution and emission characteristics were analyzed based on the data collected. The results of our study show that there were significant differences in different types of roads. The emission factors and fuel consumption rates on arterial roads and residential roads were approximately 1.4-2 times those on freeways. The carbon monoxide, hydrocarbon, and nitrogen oxides emission factors of Euro II vehicles were on average 86.2, 88.2, and 64.5% lower than those of carburetor vehicles, respectively. The new vehicle emission standards implemented in China had played an important role in reducing individual vehicle emissions. More comprehensive measures need to be considered to reduce the total amount of emissions from vehicles. 相似文献
750.
Dechlorination of octachlorodibenzo-p-dioxin (OCDD) was carried out in ethanol-water (v/v=1:1) solution of NaOH in the presence of Pd/C catalysts with the use of H(2). The substrate was dechlorinated with Pd/C under mild conditions (atmospheric pressure and <100 degrees C) to give a chlorine-free product, dibenzo-p-dioxin (DD), in high yields. After reaction of 3h at 50 degrees C, 95.9% OCDD was degraded to low dechlorinated congeners and the yield of DD was 77.4%. We have also studied the dechlorination selectivity of chlorine atoms on the different substituted positions and postulated the dechlorination pathway of OCDD. For OCDD, the 2-position has higher reactivity than 1-position, but the difference is very small. From the distribution statistics of the intermediates during the reaction, we postulate that the steric effect plays an important role during the reaction and affect the dechlorination pathway of OCDD. 相似文献