全文获取类型
收费全文 | 2498篇 |
免费 | 194篇 |
国内免费 | 1000篇 |
专业分类
安全科学 | 188篇 |
废物处理 | 123篇 |
环保管理 | 202篇 |
综合类 | 1604篇 |
基础理论 | 422篇 |
污染及防治 | 748篇 |
评价与监测 | 143篇 |
社会与环境 | 147篇 |
灾害及防治 | 115篇 |
出版年
2024年 | 5篇 |
2023年 | 59篇 |
2022年 | 179篇 |
2021年 | 160篇 |
2020年 | 144篇 |
2019年 | 126篇 |
2018年 | 118篇 |
2017年 | 156篇 |
2016年 | 129篇 |
2015年 | 168篇 |
2014年 | 243篇 |
2013年 | 258篇 |
2012年 | 221篇 |
2011年 | 206篇 |
2010年 | 164篇 |
2009年 | 144篇 |
2008年 | 174篇 |
2007年 | 142篇 |
2006年 | 120篇 |
2005年 | 83篇 |
2004年 | 60篇 |
2003年 | 94篇 |
2002年 | 90篇 |
2001年 | 75篇 |
2000年 | 44篇 |
1999年 | 55篇 |
1998年 | 39篇 |
1997年 | 42篇 |
1996年 | 51篇 |
1995年 | 28篇 |
1994年 | 17篇 |
1993年 | 16篇 |
1992年 | 21篇 |
1991年 | 17篇 |
1990年 | 7篇 |
1989年 | 13篇 |
1988年 | 11篇 |
1987年 | 2篇 |
1986年 | 5篇 |
1985年 | 2篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1982年 | 1篇 |
1981年 | 1篇 |
排序方式: 共有3692条查询结果,搜索用时 328 毫秒
991.
Contributions of deposited particles to pine needle polycyclic aromatic hydrocarbons 总被引:4,自引:0,他引:4
Yang P Chen J Wang Z Qiao X Cai X Tian F Ge L 《Journal of environmental monitoring : JEM》2007,9(11):1248-1253
The contributions of deposited particles (P) to polycyclic aromatic hydrocarbon (PAH) levels in pine (Cedrus deodar) needles sampled from the Dalian region were evaluated by washing off the particles from pine needle surfaces. P values ranged from 4.4 +/- 2.2% for fluorene to 69.9 +/- 4.0% for indeno(1,2,3-cd)pyrene, and positively correlated with the logarithm of octanol-air partition coefficients (log K OA) of each PAH significantly. P and the total levels of 14 PAHs under study ( summation PAHs), that ranged from 490 to 3241 ng g(-1) dw (dry weight) with median value of 1521 ng g(-1) dw, were high for traffic areas, and low for residential or park areas, implying the significant contributions of PAHs in both gas and particle phases emitted by vehicles. However, PAH profiles in pine needles were not significantly altered by the washing, due to the low fractions (2-5%) of the 5- and 6-ring PAHs in summation PAHs. The high wind speed and frequently alternating wind directions in the Dalian spring could quicken the depuration processes of pine needle PAHs. Thus, the local meteorological conditions and source variations should be taken into account when using pine needles to implicate seasonal variations of atmospheric semi-volatile organic compounds. 相似文献
992.
In this work, the formation of the inclusion complex of bisphenol Z (1,1-bis(4-hydroxyphenyl)cyclohexane, abbreviated as BPCH) with beta-cyclodextrin (beta-CD) has been studied, 1:1 inclusion complex can be obtained, the formation constant of the beta-CD/BPCH complex is 5.94x10(3)M(-1). The photodegradation behavior of BPCH was investigated under monochromatic UV irradiation (lambda=254 nm). The photodegradation rate constant of BPCH in aqueous solutions with beta-CD showed a 9.0-fold increase, and simultaneously the mineralization of BPCH can be enhanced by beta-CD. The influence factors on photodegradation of BPCH were also studied and described in details, such as concentration of beta-CD, initial concentration of BPCH, organic solvent and pH. The photodegradation of BPCH in the presence of beta-CD includes the direct photolysis and the photooxidation of BPCH during the photochemical process. Some predominant photodegradation products are 4-(2,4,5-trihydroxy-phenyl)-4-(4-hydroxyphenyl) butanoic acid, 5,5-bis(4-hydroxyphenyl)pentanoic acid, meta-hydroxylated BPCH, ortho-hydroxylated BPCH and 4-(1-(4-hydroxyphenyl)pentyl)phenol respectively. The enhancement of photodegradation of BPCH mainly results from moderate inclusion depth of BPCH molecule in the beta-CD cavity. This kind of inclusion structure allows BPCH molecule sufficient proximity to secondary hydroxyl groups of the beta-CD cavity, and these hydroxyl groups could be activated and converted to hydroxyl radicals under UV irradiation, which can enhance the photooxidation of BPCH. 相似文献
993.
The role of ammonia on mercury leaching from coal fly ash 总被引:1,自引:0,他引:1
The Federal Clean Air Interstate Rule issued in March 2005 will result in many power plants employing ammonia-based technologies to control NO(x) emission. The Clean Air Mercury Rule, issued at the same time, will encourage many power plants to use various technologies to remove mercury from flue gas, generating fly ashes that contain elevated concentrations of mercury. Ammonia forms relatively strong complexes with mercury compared to most other cationic elements and, therefore, may change the leaching characteristics of mercury. Understanding the impact of ammonia on the leaching of mercury from fly ash is critical in predicting the potential environmental impact of future fly ash. Batch methods were used to investigate the ammonia impact on mercury leaching from fly ash under different pH conditions. The results indicated that mercury leaching without external ammonia addition is not significant. However, ammonia addition increased mercury leaching in the alkaline pH range, due to the formation of less adsorbable mercury-ammonia complexes. Washed ash released more mercury than the raw ash if the ammonia concentration is the same, mainly due to the dissolution of some ash components during washing which exposed more mercury on ash surface. Mercury adsorption data indicated that more than 90% of available mercury was adsorbed by fly ash even in the presence of 1000 mg l(-1) ammonia addition. 相似文献
994.
基于2000~2018年中国31个省(自治区、直辖市)的面板数据,构建包含非对称价格效应的面板协整与面板误差修正模型,分体系对我国公路交通直接能源回弹效应的长期和短期影响进行实证研究。结果表明:长期中,公路客运交通与公路货运交通直接能源回弹效应分别为21%和62%;短期中,公路客运交通直接能源回弹效应为24%,而公路货运交通则出现了超级节能效应。公路货运交通对燃料价格的变动相较于公路客运交通更加敏感,因此公路货运交通直接能源回弹效应程度要大于公路客运交通。从直接能源回弹效应程度看,控制公路交通部门能源消费量仍应当以提高能源效率为主要手段,同时采取税收等相应的辅助措施来抑制能源回弹效应的负面影响。 相似文献
995.
采用频率为20kHz的超声波处理二甲苯、丙稀腈、苯酚溶液。实验结果表明,在二甲苯初始质量浓度为27.6mg/L、H2O2质量浓度为1.68g/L、溶液温度为25℃、声强为141.32W/cm^2、辐射全程时间为60min的条件下,二甲苯降解率可达99.20%;在丙烯腈初始质量浓度为100.0mg/L、通氧量为15mL/rain、溶液温度为28℃、声强为141.32W/cm^2、辐射全程时间为30rain的条件下,丙烯腈降解率可达98.20%;在苯酚初始质量浓度为20.0mg/L、H202质量浓度为1.50g/L、FeSO4质量浓度为0.22g/L、溶液温度为28℃、声强为48.92W/cm^2、辐射全程时间为40rain的条件下,苯酚降解率可达99.81%。 相似文献
996.
997.
上海市城区非渗透性地面径流的污染特性研究 总被引:27,自引:16,他引:11
通过2003~2005年连续3 a对上海市城区非渗透性地表径流的采样与检测,获得了19个采样点56组径流水样污染物(COD、BOD5、SS、NH+4-N、TP、TN)浓度随降雨历时的变化过程线.据此分析了径流污染物浓度的变化规律及其与降雨特性之间的关系,计算了地表径流水质的事件平均浓度,分析了事件平均浓度的分布规律及其与降雨特性参数之间的相关关系.研究表明,上海市区非渗透性地面径流事件平均浓度中值(mg/L)为:COD 205,BOD5 68,SS 185,NH+4-N 3.14,TP 0.40,TN 7.23,大大高于法国巴黎同类研究的结果;BOD5与COD的比值约为0.37,明显高于发达国家相关监测的结果.结果表明,上海市城区地表径流污染严重,即使实现了理想的分流制也难以控制面源污染对城市水环境的危害. 相似文献
998.
999.
1000.
Ji-Quan Shi Ziqiu Xue Sevket Durucan 《International Journal of Greenhouse Gas Control》2007,1(4):473-480
This paper reports on an integrated laboratory and numerical simulation study of ultrasonic P-wave velocity response to supercritical CO2 displacement of pore water in Tako sandstone. The analysis of dynamic velocity data recorded using an array of piezoelectric transducers mounted on a core sample showed that the P-wave velocities at different positions displayed a similar trend in time, i.e., an initial sharp fall followed by a more gradual decline. Considerable variations observed in the measured P-wave velocity reductions across the sandstone core could largely be attributed to the final state of saturation (e.g. uniform, patchy or in-between) attained by the two-phase fluids. Numerical simulation of the injection test using a simple 1D model was carried out to provide an estimation of the phase saturation changes underlying the measured P-wave velocity reductions. A second order polynomial correlation between the measured ultrasonic P-wave velocity reductions and the estimated CO2 saturation was established. Comparison with the Gassmann velocities showed that the empirically established relationship marks a clear deviation from both the patchy and uniform saturation velocity curves. 相似文献