全文获取类型
收费全文 | 7970篇 |
免费 | 231篇 |
国内免费 | 1800篇 |
专业分类
安全科学 | 413篇 |
废物处理 | 497篇 |
环保管理 | 668篇 |
综合类 | 3050篇 |
基础理论 | 1571篇 |
环境理论 | 2篇 |
污染及防治 | 2799篇 |
评价与监测 | 427篇 |
社会与环境 | 349篇 |
灾害及防治 | 225篇 |
出版年
2023年 | 80篇 |
2022年 | 304篇 |
2021年 | 219篇 |
2020年 | 152篇 |
2019年 | 182篇 |
2018年 | 267篇 |
2017年 | 283篇 |
2016年 | 309篇 |
2015年 | 334篇 |
2014年 | 409篇 |
2013年 | 766篇 |
2012年 | 455篇 |
2011年 | 608篇 |
2010年 | 417篇 |
2009年 | 437篇 |
2008年 | 524篇 |
2007年 | 469篇 |
2006年 | 411篇 |
2005年 | 295篇 |
2004年 | 289篇 |
2003年 | 327篇 |
2002年 | 259篇 |
2001年 | 368篇 |
2000年 | 287篇 |
1999年 | 183篇 |
1998年 | 144篇 |
1997年 | 163篇 |
1996年 | 117篇 |
1995年 | 127篇 |
1994年 | 105篇 |
1993年 | 102篇 |
1992年 | 86篇 |
1991年 | 84篇 |
1990年 | 54篇 |
1989年 | 43篇 |
1988年 | 27篇 |
1987年 | 25篇 |
1986年 | 24篇 |
1985年 | 20篇 |
1984年 | 24篇 |
1983年 | 26篇 |
1982年 | 26篇 |
1981年 | 18篇 |
1980年 | 12篇 |
1979年 | 14篇 |
1978年 | 12篇 |
1977年 | 8篇 |
1975年 | 13篇 |
1973年 | 9篇 |
1972年 | 10篇 |
排序方式: 共有10000条查询结果,搜索用时 412 毫秒
191.
赵喜萍 《辽宁城乡环境科技》2006,26(1):39-41
根据某污水处理场沉淀池的COD和SS去除率较低的情况,文中着重探讨了问题的产生原因,并针对平流式沉淀池及斜管式沉淀池提出了相应的改进方案,实践证明改进后提高了COD和SS去除率30%,并明显降低了二级生物处理阶段的有机物负荷,节省了大量的暴气量通过改进达到了降低处理场其它环节的负荷和降低污水处理成本的目的。 相似文献
192.
193.
194.
195.
以石家庄市显像管玻壳厂排放的铅尘为研究对象,通过在该玻壳厂周围土壤布点采样,较系统地研究了铅尘在大气和周围土壤中的迁移和转化规律,研究表明,用高斯模式能成功地预测铅尘在大气中的迁移扩散规律,玻壳厂周围土壤表层铅含量较大值出现在当地年主导风向(SSE,N)下风向,铅在土壤中的分布主要集中在0-20cm的耕作层,在20-40cm深度范围内,铅含量呈下降趋势,最大降幅达50%。 相似文献
196.
197.
The application of ultrasonic-electrolysis process for the removal of copper is studied.In the ultrasonic field cavitation acts as jets and agitates the solution and breaks the barrier layer between the cathode surface and the bulk of the solution.Thus increases metal deposition on the cathode surface.The results show that an ultrasonic field is successful for the removal of low copper concentrations in solution. 相似文献
198.
对一种富烯土型三效催化剂的性能进行了考察,结果表明:该催化剂具有较好的三效活性和较好的启燃温度特性,具有较宛的空速适应范围,在空速为84000h^-1时,CO,NOx的转化率仍在90%以上,HC转化率仍在70%以上,该催化剂具有较好的耐老化性能,经实验室快速老化实验,即相当于实车行驶8万km,CO劣化系数,1.09,HC劣化系1.05,NOx劣化系数1.06,该催化剂经桑塔纳轿车整车28工况测试,其交化效果与该车配置的美国Engelherd公司的催化剂相当。 相似文献
199.
Zhang YJ Bryan ND Livens FR Jones MN 《Environmental pollution (Barking, Essex : 1987)》1997,96(3):361-367
The interactions of a range of actinide elements (Th, U, Np, Pu, Am) with humic substances from the Needle's Eye natural analogue site were studied by gel permeation chromatography. Bulk humic substances were isolated by ammonia extraction, followed by dialysis against distilled water and freeze-drying. The gel permeation results suggest that Needle's Eye humic substances can be fractionated into three incompletely resolved fractions with average molecular weights determined by analytical ultracentrifugation around 49 000 for Fraction 1, around 14 700 for Fraction 2 and around 8000 for Fraction 3. Although there are significant differences between the organic matter elution patterns in individual gel permeation experiments, presumably due to differences in column packing, these are much smaller than the differences between metal ions. The uranium that is naturally present in these humic substances is largely bound in the late-eluting fraction. Spikes of the early actinides, including Np and Pu in controlled valency states, have been added to the humic substances, and gel permeation of the spiked humic substances shows that the three humic fractions vary greatly in their effectiveness and selectivity as ligands for early actinides. 相似文献
200.
The perturbant effects of four Triton adjuvants, namely Triton X-15, X-35, X-100, and X-114 (alkyl aryl polyether alcohols), on some of the biochemical determinants of membrane integrity were determined under laboratory conditions. Two of these, Triton X-100 and X-114, are currently being assessed as emulsifiers for use in fenitrothion insecticidal formulations. Lemna minor L. plants were exposed to 40 microM (10-25 microg ml(-1) in 965 microg mg(-1) Dowanol (tripropylene glycol methyl ether) carrier solvent) adjuvant for a treatment time period of two weeks. A decrease in the contents of the total phospholipids and a concomitant increase in the contents of the galactolipids were found. No change was observed in the total lipid content. An unsaturation occurred in the fatty acids of the total lipids, phospholipids, and monogalactosyl diacylglycerides. This accounted for a significant decrease in palmitic and stearic acids and a concomitant increase in oleic, linoleic, and linolenic acids when these are compared with the fatty acids in the nontreated control sets. The fatty-acid profile of the digalactosyl diacylglycerides, however, differed only slightly from controls. Membrane-fatty-acid unsaturation suggests the possibility of a desaturase enzyme's being induced by these adjuvants. 相似文献