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141.
废印刷电路板的静电分选实验研究 总被引:1,自引:0,他引:1
金属与非金属材料的分离是回收利用废印刷电路板的关键环节。对废印刷电路板物料的静电分选进行了实验研究。实验以电压、辊筒转速、电晕电极与辊筒之间的距离、静电极位置、电晕电极位置、电晕电极数量等为考察因素,研究各因素对电选效果的影响规律。结果表明,影响金属与非金属材料分离的主要因素是电压、辊筒转速和电晕电极与辊筒之间的距离,对于-0.9 0.45mm的破碎物料,当电压为24kV,辊筒转速为15Hz(54.6r/min),电晕电极与辊筒之间的距离为5.2cm时,得到最大静电分选综合效率67.37%。 相似文献
142.
143.
Gao Xing Wang Jie Li Chenxi Shen Weining Song Zhaoying Nie Chengjing Zhang Xueru 《Environmental science and pollution research international》2021,28(24):31043-31058
Environmental Science and Pollution Research - Simulating changes in the value of ecosystem services caused by land use changes in large cities under multiple scenarios is of great significance for... 相似文献
144.
The feasibility of the rapid degradation of hexachlorobenzene (HCB) by micron-size silver (Ag)/iron (Fe) particles was investigated.Ag/Fe particles with different ratios (0,0.05%,0.09%,0.20%,and 0.45%) were prepared by electroless silver plating on 300 mesh Fe powder,and were used to degrade HCB at different pH values and temperatures.The dechlorination ability of Fe greatly increased with small Ag addition,whereas too much added Ag would cover the Fe surface and reduce the effective reaction surface,thereby decreasing the extent of dechlorination.The optimal Ag/Fe ratio was 0.09%.Tafel polarization curves showed that HCB was rapidly degraded at neutral or acidic pH,whereas low pH levels severely intensified H2 production,which consumed the reducing electrons needed for the HCB degradation.HCB degradation was more sensitive to temperature than pH.The rate constant of HCB dechlorination was 0.452 min-1 at 85℃,50 times higher than that at 31℃.HCB was degraded in a successive dechlorination pathway,yielding the main products 1,2,4,5-tetrachlorobenzene and 1,2,4-trichlorobenzene within 2 hr. 相似文献
145.
The optical beam deflection method was applied to study the effects of acid solution on both a terrestial and aquatic plants Egeria and Cerastium, which are common aquatic plant and terrestial weed respectively. A probe beam from a He-Ne laser was passed through a vicinity of a leaf of the plants, which were put in culture dishes filled with acid solutions. Deflection signals of the probe beam were monitored and compared for acid solutions with different pH values. The results of Egria showed that the deflection signals changed dramatically when pH values of acid solutions were 2.0 and 3.0, while little at pH of 4.0 and 5.0. For Cerastium when pH were below 3.0, deflection signals changed greatly with time at the begining. After a certain period of time, deflection signals changed little with time. When pH value was above 4.0, deflection signals of Cerastium were still changing with time even after 20 hours. The results suggested that the damage threshold of pH was between 3.0 and 4.0 for both the land and aquatic plants. 相似文献
146.
147.
Kai Liu Fangbai Li Qingwen Tian Chengrong Nie Yibing M Zhenlong Zhu Liping Fang Yuanying Huang Siwen Liu 《环境科学学报(英文版)》2021,33(6):27-39
Paddy soil and irrigation water are commonly contaminated with hexavalent chromium [Cr(VI)] near urban industrial areas, thereby threatening the safety of agricultural products and human health. In this study, we develop a porous and high specific area bone char (BC) to support nanoscale zero-valent iron (nZVI) and apply it to remediate Cr(VI) pollution in water and paddy soil under anaerobic conditions. The batch experiments reveal that BC/nZVI exhibits a higher removal capacity of 516.7 mg/(g?nZVI) for Cr(VI) than nZVI when normalized to the actual nZVI content, which is 2.8 times that of nZVI; moreover, the highest nZVI utilization is the nZVI loading of 15% (BC/nZVI15). The Cr(VI) removal efficiency of BC/nZVI15 decreases with increasing pH (4 – 10). Coexisting ions (phosphate and carbonate) and humic acid can inhibit the removal of Cr(VI) with BC/nZVI15. Additionally, BC exhibits a strong advantage in promoting Cr(VI) removal by nZVI compared to the widely used biochar and activated carbon. Our results demonstrate that reduction and coprecipitation are the dominant Cr(VI) removal mechanisms. Furthermore, BC/nZVI15 shows a significantly higher reduction and removal efficiency as well as a strong anti-interference ability for Cr(VI) in paddy soil, as compared to nZVI. These findings provide a new effective material for remediating Cr(VI) pollution from water and soil. 相似文献
148.
通过对2009年11月12日在四川省广元市三堆镇马口村举行的自然灾害应急演练进行初步的分析研究,总结出了从前期准备、正式实施到演练评估的农村社区自然灾害应急演练基本流程和方法。在马口村自然灾害应急演练的前期准备阶段,根据当地实际情况选择了滑坡、泥石流为演练的自然灾害背景,制定了3级响应演练模式,并细化了各级响应的启动标准。在演练的正式实施阶段,采用了参与式的演练方案设计方法,充分调动了当地群众的积极性。演练结束后在现场发放调查问卷,对演练进行了多方面、多角度的评估,演练基本达到了预定目标。 相似文献
149.
昆明市东川区农业旱灾风险区识别研究 总被引:3,自引:0,他引:3
昆明市东川区是云南省农业旱灾危害较为严重的区域之一。利用2000-2007年东川区各乡镇历史灾情等数据资料,应用风险分析理论、效用理论、因子-成份分析方法等理论方法,在分别研究致灾风险度、承灾体易损性及地域人群对农业旱灾心理反响等基础上,构建了东川区农业旱灾风险评价模型。初步揭示出东川区农业旱灾风险度呈现出自南向北、自西向东逐渐增强的空间态势;识别出极高风险区、高风险区、中风险区和低风险区等4个农业旱灾风险区;发现东川区各地农业旱灾综合风险度、致灾风险度、承灾体易损度以及地域人群对旱灾的心理响应值等指数之间普遍存在着明显的正相关。 相似文献
150.
Toxic metal (Pb, Cd, As and Hg) and organochlorine residue levels in hake (Merluccius merluccius) from the Marmara Sea, Turkey 总被引:1,自引:0,他引:1
Toxic metals (Pb, Cd, As and Hg) and organochlorine residue levels were measured in hake (Merluccius merluccius) from the Marmara Sea. Biota samples were collected by a trawling cruise of the R/V ARAR in August and December 2009. The concentrations of toxic metals varied between Pb, 3.23-14.4; Cd, <0.01-2.14; Hg, 0.01-0.18 and As, 0.01-0.21 [Formula: see text]g g(-1) dry wt. Pb levels in the Marmara Sea were found to be higher than the critical limits set by the both Turkish Ministry of Environment for Aquatic Products (1 μg g(-1) wet wt.) and European countries (2.0 μg g(-1), UNEP 1985). In contrast, As and Hg levels were found to be lower than the critical limits for two periods. Cd contents of fish from the Marmara Sea were also comparable to or slightly lower than contents of fish from the Southern Black Sea Shelf. The results of organochlorine residues ranged between total HCH, <0.05 and 99 ng g(-1); endrin, <0.001 and 381 ng g(-1); alpha-endosulphan, <0.05 and 90 ng g(-1); beta-endosulphan, <0.05 and 15.3 ng g(-1); o,p DDE, 3.5 and 52.4 ng g(-1); p,p DDE, 7.4 and 139 ng g(-1); o,p DDD, 1.5 and 90.2 ng g(-1) and p,p DDD, 2.7 and 86 ng g(-1) wet weight. The rivers for the distribution of organochlorine levels in the Marmara Sea ordered from highest to lowest as Dil R. > Susurluk R. > Biga R. > G?nen R. The high levels of o,p and p,p DDE, and o,p and p,p DDD compounds, which are metabolites of DDT, indicate its illegal use. Toxic metal and organochlorine residue levels of fish are significantly higher than levels from the Mediterranean Sea. 相似文献