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251.
结合风险感知影响因子的研究,通过对风险的概念性剖析,将客观与主观性概念相整合提出了一个相对简单,但具有较强应用性的方法并应用于风险感知的定量化研究中.模型是通过定量的方式表达出人们的风险厌恶和风险接受等心理上的风险特征.该方法整合了个体风险效率Reff和相对感知影响因子(PAF)的权重平均值,模型的核心理念是基于心理测量范式方法.在模型中给每一个PAF分配1个相关权重以代表其影响力大小.权重值的量化过程通过目标一组的方式(如专家、大众)或者心理测量范式的方法进行.对可选择性的PAF生成过程与权重值的计算方法进行了详细阐述.同时,利用专家工作组的数据进行了真实性检验.检验结果表明:模型能够应用于标准化与技术性的个体风险感知定量分析,如用于改善并加强专家与大众之间的风险沟通,减小他们之间的风险感知差异等;另外,该方法能够解释风险感知水平的差异是如何形成的,但并不能解释为什么形成了这样的差异.该结构化的计算模型的建立过程既没有过多地考虑社会-文化因子,也没有考虑历史背景,因为这两个影响因子的影响是十分微弱的. 相似文献
252.
Rapid degradation of carbon tetrachloride by commercial micro-scale zinc powder assisted by citric acid 总被引:1,自引:0,他引:1
Xianchao Gao Feng Yang Yeqing Lan J.-D. Mao Xinyan Duan 《Environmental Chemistry Letters》2011,9(3):431-438
We developed an effective method for degradation of carbon tetrachloride (CT) in contaminated water. Zinc metal as a reducing
agent for CT in aqueous solutions has been previously studied in some detail, but the rapid corrosion of zinc surface usually
reduces its efficiency in removing CT. We assumed that citric acid could enhance the degradation of CT by zinc powder due
to the elimination of a passivation layer of Zn(II) (hydr)oxides on the surface of zinc powder through chelating of organic
ligands with Zn(II) produced from the reaction and keeping the exposure of active sites to targets. Here the influence of
citric acid on the decomposing of CT by commercial micro-scale zinc powder was investigated in a pH range of 3.5–7.5 at 25°C
in batch experiments. Reaction mixtures were analysed by gas chromatography/headspace analysis, and Cl− concentration was determined by turbidimetry. The results demonstrate that the degradation of CT by zinc metal alone is very
weak, but the addition of citric acid can assist zinc powder to decompose CT more completely and rapidly at all pHs. Degradation
of CT took place mainly in the first 10 min of reaction, coupled with 75–95% of CT removal. Maximum dechlorination percentage
(82.4%) of CT was obtained at pH 5.5. In that case, chloroform and dichloromethane, as main intermediates, were found at low
levels during the whole reaction, suggesting that CT may be sequentially and multiply degraded so quickly that methane is
yielded before the intermediates can be desorbed and released to aqueous solution. When compared with the current methods
of nano-scale zinc and bimetallic systems, the application of commercial micro-scale zinc particles assisted by organic ligands
is of environmental significance since it allows decontamination of aqueous chlorinated organic compounds at low cost and
with high efficiency. 相似文献
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254.
应急预案是迅速、有序、有效地开展应急救援行动的保障。提出了石油化工企业应急预案的框架结构,并对预案编制过程中的难点进行了分析。 相似文献
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258.
介绍了如何综合利用数据库、GPS、GIS、GSM网络MS技术、数据传输等多项技术,设计、开发GPS安全实时巡检系统,实践表明,GPS安全实时巡检系统在天然气管道巡检、信息系统管理、安全管理等方面取得了较好的成效. 相似文献
259.
Phthalates are widely used in industry and consumer products. Di-(2-ethylhexyl) phthalate (DEHP) and di-n-butylphthalate (DBP) show the greatest potency of reproductive toxicants among phthalates. The purposes of this study are to examine the migration level of phthalate from PVC films by simulating food handling and to reveal the body burden of phthalate for Taiwanese. In order to estimate a worst-case of phthalate migration, food was covered with polyvinyl chloride (PVC) films and then microwave heated. Results show that DEHP level in food increased significantly after heating for 3 min. Under the heating condition, the calculated intake of phthalate and the percentage of the tolerable daily intake (TDI, based on body weight of 60 kg) from eating one 400-g meal were 1705.6 microg and 92.2% for DEHP. Determination of urinary metabolites from 60 subjects reveals more than 90% of samples were detectable for mono-methyl phthalate (MMP), mono-butyl phthalate (MBP) and mono-ethylhexyl phthalate (MEHP). Notably, the median value of estimated daily intake of DEHP had reached 91.6% of TDI established by the European Union Scientific Committee for Toxicity, Ecotoxicity and the Environment (CSTEE) (1998). Thirty-seven percent of the study population exceeded the TDI and 85% exceeded the reference dose (RfD) of the US EPA. We conclude that the body burden of DEHP for Taiwanese reflects the intensives use of plastic materials in the region. The regulation of PVC for food preparation is necessary. 相似文献
260.
南沙港网箱养殖水域沉积环境质量评价 总被引:1,自引:0,他引:1
2007-01至2007-11分4个航次对宁波南沙港网箱养殖区沉积物环境质量状况进行了现场调查,利用MOM—B系统的三个子集参数对沉积环境质量进行了评价。结果表明:子集1得出2007-01的平均分数小于0.5,而-2007—04、2007—07以及2007—11的平均分数均大于0.5;子集2得出4个季节沉积物的pH和氧化还原电位变化范围分别为7.15—8.33和-197.5m~-105my;子集3得出4个航次得到的平均分数介于4和10之间;综合3个子集的结果来看,南沙港网箱养殖区沉积物环境质量状况冬季为2级,春季、夏季和秋季均属于4级严重污染状态。 相似文献