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排序方式: 共有229条查询结果,搜索用时 15 毫秒
221.
根瘤菌菌体及胞外多糖红外光谱特征 总被引:2,自引:0,他引:2
记录并分析了根瘤菌4个新类群菌株的菌体与胞外多糖的红外光谱,表明它们在特定光谱区显示特征吸收峰.根瘤菌菌体光谱特征在鉴定上具有一定意义;胞外多糖的结构为β-配糖键连接,其光谱特征与数值分类结果关系不明显 相似文献
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223.
Rodrigo T. de Paula Adley Bergson G. de Abreu Antônio A. Neves Antônio A. da Silva 《Journal of environmental science and health. Part. B》2016,51(2):90-95
This study evaluated the mobility and persistence of atrazine and ametryn in red–yellow latosols using polyvinyl chloride columns with a diameter of 100 mm and a height of 15 cm. The assays simulated 60-mm rainfall events at 10-day intervals for 70 days. The persistence and leaching were evaluated for these two herbicides. The analytes obtained from the samples were quantified by gas chromatography using flame ionization detection. Compared with ametryn, atrazine showed a greater potential to reach depths below 15 cm over 30 days of simulated rain. Ametryn, however, showed greater persistence in soil at 70 days after application. The persistence of atrazine and ametryn in soil under sunlight was 10 and 144 days respectively. Atrazine was more susceptible to sunlight than ametryn because sunlight favored atrazine degradation in hydroxyatrazine. The results indicate that in red–yellow latosol, atrazine has a high leaching potential in short term, but that ametryn is more persistent and has a high leaching potential in long term. 相似文献
224.
采用溶胶-凝胶法制备了La2O3-Ti O2光催化剂;运用XRD,UV-Vis DRS,BET技术对光催化剂进行了表征;并以太阳光为光源,研究了不同制备条件及光反应条件下La2O3-Ti O2对罗丹明B的降解效果。实验结果表明:最佳制备条件为镧掺杂量(硝酸镧与钛酸丁酯的质量比)0.9%、焙烧温度500℃、焙烧时间2 h;该条件下制备的光催化剂为中孔结构(平均孔径3.867 nm),禁带宽度小(2.07 e V),Ti O2为锐钛矿相;在光催化剂投加量为2 g/L、溶液p H为3的最佳光反应条件下反应4 h,La2O3-Ti O2对罗丹明B的降解率达99.7%,远高于N-Ti O2的42.0%;重复使用5次的La2O3-Ti O2光催化剂仍对罗丹明B保持较高的降解率(98.5%)。 相似文献
225.
不同垃圾渗滤液组合处理工艺中DOM的变化特征 总被引:1,自引:0,他引:1
为了快速表征垃圾渗滤液处理过程中有机物的特性变化,分别采用紫外光谱和三维荧光光谱对2种垃圾渗滤液处理工艺不同单元溶解性有机物(DOM)的变化进行了系统分析。结果表明,二级RO和厌氧+好氧+MBR+NF+RO工艺对渗滤液COD和NH3-N的去除率分别为98.7%、99.0%和98.8%、98.6%。随着处理过程的进行,2个处理工艺中DOM的SUVA254、E253/E203分别由0.74、0.33和0.46、0.12下降至0.015、0.014和0.010、0.012,有机物的芳香性和不饱和性下降,脂肪链芳香烃化合物开始增加。不同处理阶段渗透液DOM三维荧光光谱表明,随着处理过程的进行,类富里酸和类蛋白物质的含量逐渐下降,芳构化程度开始降低。其中二级RO系统对渗滤液中类富里酸物质的去除效果较好,而厌氧-好氧-MBR-NF-RO工艺中,类酪氨酸物质主要通过微生物降解去除,NF和RO膜对类富里酸和类腐殖酸物质的截留效果较好。 相似文献
226.
K.M.S. Sundaram 《Journal of environmental science and health. Part. B》2013,48(4):523-544
Abstract Foliar deposits, volatilization and persistence of azadirachtin‐A (AZ‐A) were investigated after application of four spray mixes prepared from a wettable powder (WP) and three emulsifiable concentrate (EC) formulations of neem. They were applied at the dosage rate of 50 g AI in 4 L/ha onto potted spruce seedlings in a laboratory spray chamber. Droplet‐size spectra and deposits were assessed using Kromekote® card/glass plate collection units. Foliar residues [dislodgeable residues (DR), penetrated residues (PR) and total residues (TR)] of AZ‐A and their volatilization were measured by HPLC at different intervals of time up to 60 h after treatment. Differences in the droplet‐size spectra and deposit levels were observed among the four spray mixes due to the influence of additives present in them. Dissipation half‐lives (DT50) of the DR, PR and TR in the foliage were low (range, 19.5 to 38.9 h) and varied according to the residue type and the spray mix used. The DT50 values of the DR were consistently lower (range, 19.5 to 31.9 h) than those of the PR (range, 30.5 to 38.9 h) due to preferential loss of the surface residues. The low DT50 values observed for the DR and TR in the foliage sprayed with the WP spray mix were attributed to the particulate nature of the deposit. AZ‐A volatilized appreciably from the DR rather than from the PR. The variations found in the amounts of AZ‐A volatilized (42 to 58%) and unaccountable (38 to 46%) from the initial TR values in spruce foliage, after 60 h, were attributed to the physical form of the deposits on the target surface and the influences of additives present in the different spray mixes. 相似文献
227.
The nitroaromatic compounds 2,4,6-trinitrotoluene (TNT), 2,4-dinitrotoluene (DNT) and 2,4-dinitroanisole (DNAN) are potential environmental contaminants and their transformations under a variety of environmental conditions are consequently of great interest. One possible method to safely degrade these nitrocompounds is alkaline hydrolysis. A mechanism of the initial stages of this reaction was investigated computationally. Simulations of UV-VIS and NMR spectra for this mechanism were also produced. The results obtained were compared to available experimental data on the alkaline hydrolysis of TNT and suggest that the formation of Meisenheimer complexes and an anion of TNT are potential first-step intermediates in the reaction path. As the reaction proceeds, computational results indicate that polynegative complexes dominate the degradation pathway, followed by cycles of carbon chain opening and breaking. A second possible pathway was identified that leads to polymeric products through Janovsky complex formation. Results from this study indicate that the order of increasing resistance to alkaline hydrolysis is TNT, DNT and DNAN. 相似文献
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通过建立"腐蚀环境综合试验仓"、"温度、湿度、日照、淋雨综合试验仓"、"高原环境试验仓"三个大型试验仓,构建成可模拟我国不同地域大气环境,可针对大尺寸工程构件,系统开展环境适应性评价的实验装置. 相似文献