全文获取类型
收费全文 | 954篇 |
免费 | 129篇 |
国内免费 | 101篇 |
专业分类
安全科学 | 308篇 |
废物处理 | 19篇 |
环保管理 | 95篇 |
综合类 | 452篇 |
基础理论 | 100篇 |
污染及防治 | 62篇 |
评价与监测 | 112篇 |
社会与环境 | 13篇 |
灾害及防治 | 23篇 |
出版年
2024年 | 3篇 |
2023年 | 19篇 |
2022年 | 37篇 |
2021年 | 45篇 |
2020年 | 52篇 |
2019年 | 47篇 |
2018年 | 26篇 |
2017年 | 39篇 |
2016年 | 35篇 |
2015年 | 47篇 |
2014年 | 58篇 |
2013年 | 71篇 |
2012年 | 77篇 |
2011年 | 73篇 |
2010年 | 50篇 |
2009年 | 50篇 |
2008年 | 60篇 |
2007年 | 68篇 |
2006年 | 52篇 |
2005年 | 48篇 |
2004年 | 30篇 |
2003年 | 34篇 |
2002年 | 25篇 |
2001年 | 21篇 |
2000年 | 12篇 |
1999年 | 13篇 |
1998年 | 19篇 |
1997年 | 11篇 |
1996年 | 14篇 |
1995年 | 10篇 |
1994年 | 8篇 |
1993年 | 4篇 |
1992年 | 3篇 |
1991年 | 3篇 |
1990年 | 4篇 |
1989年 | 3篇 |
1988年 | 5篇 |
1987年 | 1篇 |
1986年 | 1篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1982年 | 2篇 |
1977年 | 1篇 |
1972年 | 1篇 |
排序方式: 共有1184条查询结果,搜索用时 34 毫秒
81.
82.
Summary. We investigated the hypothesis that aggregation signals produced by male webbing clothes moths (WCM), Tineola bisselliella (Hum.) (Lepidoptera: Tineidae), and close-range male attractant signals produced by females have a pheromonal basis, at least
in part. Gas chromatographic-electroantennographic detection (GC-EAD) and GC-mass spectrometric analyses of bioactive methanolic
extracts of male WCM disclosed three candidate pheromone components: hexadecanoic acid methyl ester (16:Ester), (Z)-9-hexadecenoic acid methyl ester (Z9—16:Ester), and octadecanoic acid methyl ester (18:Ester). In bioassay experiments in a large Plexiglas™ arena, a blend of
synthetic 16:Ester plus Z9—16:Ester was attractive to male and virgin (but not mated) female WCM; the 18:Ester was inactive.
GC-EAD analyses of pheromone gland extracts from female WCM revealed (E,Z)-2,13-octadecadienal (E2Z13—18:Ald) and (E,Z)-2,13-octadecadienol (E2Z13—18:OH) as candidate sex pheromone components. In arena bioassay experiments, 1—5 female equivalents of synthetic E2Z13—18:Ald (0.2 ng) and E2Z13—18:OH (0.1 ng) were more attractive to male WCM than were two virgin female WCM. We anticipate that the combination of
aggregation and sex pheromones, male-produced sonic aggregation signals, and habitat-derived semiochemicals will be highly
effective in attracting male and female WCM to commercial traps.
Received 12 January 2001; accepted 8 June 2001. 相似文献
83.
煤与瓦斯突出的物理模拟和数值模拟研究 总被引:1,自引:0,他引:1
利用自行设计的实验装置,通过现场采集具有突出倾向的煤样,分别向实验装置煤样中充入吸附能力较大的CO2和吸附能力较小的N2来模拟不同级别的煤与瓦斯突出现象,物理试验结果表明:瓦斯压力越大,突出强度越大;当瓦斯压力相近时,吸附和解吸能力大的瓦斯突出强度大。通过数值模拟对煤与瓦斯突出进行研究,数值模拟再现了煤矿开采过程中诱发的煤与瓦斯突出全过程,同时验证了煤与瓦斯突出是瓦斯压力、地应力及煤岩体的力学性质综合作用的结果,该验证对进一步深入理解认识煤与瓦斯突出的机理具有重要的理论和实践意义。 相似文献
84.
85.
86.
87.
以序批式动态膜反应器为研究对象,对其处理低碳氮比废水的效果进行了试验研究.试验温度为19 ~ 21℃,MLSS为3~5g/L;好氧阶段溶解氧质量浓度为2 ~4 mg/L,厌氧阶段溶解氧质量浓度为0.2~0.5 mg/L;水力停留时间共12 h,其中好氧阶段8h,厌氧阶段4h.结果表明:当进水COD、TN和NH4+-N质量浓度分别为250~300mg/L、103 ~ 156 mg/L和92~140 mg/L时,反应器对上述污染物表现出较高且稳定的去除效率,COD、TN和NH4+-N平均去除率分别达到76.15%、82.16%和90.13%.同时,反应器系统中污泥的比硝化速率与常规处理装置中的活性污泥相比较高,以NH4+-N的降解量计为0.101 d-1,以NO3--N的积累量计为0.091 d-. 相似文献
88.
89.
During the detection of pipeline leakages, false alarms of leak detection could be markedly reduced if the interference signals resulting from pressure regulating, pump regulating or valve movements could be accurately distinguished. A digital recognition method for interference signals and leakage signals based on a dual-sensor system is proposed in this paper. It is demonstrated that the direction of the signal can be recognized by a cross-correlation calculation between two signals from the dual-sensor, one of which undergoes forward linear interpolation and backward linear interpolation. Based on this theory, the interference signal and the leak signal can be discriminated exactly, and the distance between the two sensors in the dual-sensor system can be considerably reduced without needing to increase the sampling frequency. The monotonicity of the cross-correlation function is demonstrated, and a fast discrimination algorithm based on a binary extreme search method, which decreases the computational load and maintains global optimization, is also proposed. A pre-processing method of the actual signal is proposed to decrease the identity requirement for the two sensors in a dual-sensor system. In the experiment based on artificial signals, the proposed discrimination algorithm could achieve accurate recognition of the abnormal signal, and as such, the theory and application of pipeline leak detection based on dual-sensor systems are extended. 相似文献
90.