全文获取类型
收费全文 | 6343篇 |
免费 | 105篇 |
国内免费 | 444篇 |
专业分类
安全科学 | 167篇 |
废物处理 | 333篇 |
环保管理 | 461篇 |
综合类 | 1440篇 |
基础理论 | 1492篇 |
环境理论 | 5篇 |
污染及防治 | 2137篇 |
评价与监测 | 471篇 |
社会与环境 | 330篇 |
灾害及防治 | 56篇 |
出版年
2023年 | 67篇 |
2022年 | 180篇 |
2021年 | 186篇 |
2020年 | 102篇 |
2019年 | 129篇 |
2018年 | 224篇 |
2017年 | 249篇 |
2016年 | 317篇 |
2015年 | 260篇 |
2014年 | 379篇 |
2013年 | 536篇 |
2012年 | 401篇 |
2011年 | 432篇 |
2010年 | 307篇 |
2009年 | 261篇 |
2008年 | 416篇 |
2007年 | 365篇 |
2006年 | 296篇 |
2005年 | 237篇 |
2004年 | 219篇 |
2003年 | 189篇 |
2002年 | 160篇 |
2001年 | 108篇 |
2000年 | 66篇 |
1999年 | 74篇 |
1998年 | 51篇 |
1997年 | 42篇 |
1996年 | 44篇 |
1995年 | 48篇 |
1994年 | 43篇 |
1993年 | 24篇 |
1992年 | 31篇 |
1991年 | 30篇 |
1990年 | 24篇 |
1989年 | 18篇 |
1988年 | 20篇 |
1987年 | 12篇 |
1986年 | 26篇 |
1985年 | 14篇 |
1984年 | 12篇 |
1983年 | 16篇 |
1982年 | 20篇 |
1981年 | 11篇 |
1980年 | 13篇 |
1972年 | 9篇 |
1966年 | 16篇 |
1965年 | 10篇 |
1957年 | 9篇 |
1956年 | 12篇 |
1954年 | 9篇 |
排序方式: 共有6892条查询结果,搜索用时 421 毫秒
71.
浮选剂污染河段大型底栖无脊椎动物的群落特征及其对水质的评价 总被引:2,自引:0,他引:2
利用大型底栖动物的群落结构及其行为反应对有毒化合物——浮选剂污染河段水质进行评价,并提出了受浮选剂污染的污水生物系统评价标准.结果表明,主要污染物丁基磺药对涡虫(Dugesia gonocephala)的24h LC_51为78ppm.根据受污河段底栖动物群落的变化和涡虫在各断面河水中的行为反应,浮选剂污水生物系统可以划分成α-多污带,β-多污带,α-中污带,β-中污带和寡污带。并对所提出的浮选剂污水生物系统进行了讨论。 相似文献
72.
73.
兰炼烷基化废酸处理工艺选择 总被引:1,自引:1,他引:1
对目前四种烷基化硫酸处理工艺进行了分析比较,认为兰炼应依托现有硫酸装置,采用裂解制硫酸工艺来处理烷基化废酸。 相似文献
74.
76.
The aim of this study was to determine whether there is increased leakage of neuron-specific enolase (NSE) and S-100 protein into amniotic fluid in pregnancies with neural tube defects, since both these proteins are produced by neural tissue, and to compare the value of these substances for detecting such defects with that of the more conventional techniques of alpha-fetoprotein (AFP) and acetylcholinesterase (AChE) gel electrophoresis. Amniotic samples from 25 mid-pregnancies (15–17 weeks' gestation) with neural tube defects (14 with open spina bifida and 11 with anencephaly) and from seven mid-pregnancies with abdominal wall defects were compared with a control material consisting of 80 amniotic fluid samples from 80 consecutive mid-pregnancy amniocenteses, with normal karyotypes and AFP concentrations. All of the above cases of abnormalities were primarily detected through increased AFP levels in the amniotic fluid. Amniotic fluid samples from 13 pregnancies with fetuses with autosomal chromosomal abnormalities and seven amniotic fluid samples contaminated with blood were also included in the investigation. It is concluded from the results that the conventional AFP assay combined with AChE gel electrophoresis is the best method for screening amniotic fluid for neural tube defects and defects of the abdominal wall. Neither NSE nor S-100 assay alone proved to be superior for the detection of these cases in mid-trimester amniotic fluid. The S-100 assay, however, could give additional information in cases where AChE gel electrophoresis is not decisive; for example, in samples contaminated with blood. 相似文献
77.
In this study, the two-stage upflow anaerobic sludge blanket (UASB) system and batch experiments were employed to evaluate
the performance of anaerobic digestion for the treatment of high concentration methanol wastewater. The acid resistance of
granular sludge and methanogenic bacteria and their metabolizing activity were investigated. The results show that the pH
of the first UASB changed from 4.9 to 5.8 and 5.5 to 6.2 for the second reactor. Apparently, these were not the advisable
pH levels that common methanogenic bacteria could accept. The methanogenic bacteria of the system, viz. Methanosarcina barkeri,
had some acid resistance and could still degrade methanol at pH 5.0. If the methanogenic bacteria were trained further, their
acid resistance would be improved somewhat. Granular sludge of the system could protect the methanogenic bacteria within its
body against the impact of the acidic environment and make them degrade methanol at pH 4.5. The performance of granular sludge
was attributed to its structure, bacteria species, and the distribution of bacterium inside the granule.
Translated from Acta Scientiae Circumstantiae, 2004, 24(4): 633–636 [译自: 环境科学学报] 相似文献
78.
79.
80.