全文获取类型
收费全文 | 2214篇 |
免费 | 277篇 |
国内免费 | 393篇 |
专业分类
安全科学 | 745篇 |
废物处理 | 32篇 |
环保管理 | 250篇 |
综合类 | 1315篇 |
基础理论 | 184篇 |
污染及防治 | 177篇 |
评价与监测 | 37篇 |
社会与环境 | 31篇 |
灾害及防治 | 113篇 |
出版年
2024年 | 26篇 |
2023年 | 97篇 |
2022年 | 105篇 |
2021年 | 123篇 |
2020年 | 86篇 |
2019年 | 126篇 |
2018年 | 76篇 |
2017年 | 96篇 |
2016年 | 89篇 |
2015年 | 114篇 |
2014年 | 175篇 |
2013年 | 137篇 |
2012年 | 156篇 |
2011年 | 156篇 |
2010年 | 131篇 |
2009年 | 119篇 |
2008年 | 154篇 |
2007年 | 161篇 |
2006年 | 112篇 |
2005年 | 90篇 |
2004年 | 115篇 |
2003年 | 71篇 |
2002年 | 76篇 |
2001年 | 48篇 |
2000年 | 44篇 |
1999年 | 35篇 |
1998年 | 23篇 |
1997年 | 24篇 |
1996年 | 17篇 |
1995年 | 18篇 |
1994年 | 18篇 |
1993年 | 14篇 |
1992年 | 14篇 |
1991年 | 11篇 |
1990年 | 16篇 |
1989年 | 10篇 |
1987年 | 1篇 |
排序方式: 共有2884条查询结果,搜索用时 250 毫秒
751.
752.
753.
754.
就通风空调工程中具有特殊应用的环形风道的摩擦阻力计算问题进行了分析,根据流体力学原理,提出了采用流量当量直径法和直接利用圆形风道计算图风道的比摩阻2种方法,第2种计算方法与流量当量直径法比较,查表时更直接。 相似文献
755.
失控的化学反应能够造成人员伤亡、财产损失以及环境污染等严重的事故。那么,化学反应的主要危险危害因素是什么?怎样确保安全生产和操作?需要特别说明的是,文中提及的措施虽然原则上可适用于所有企业,但主要是针对中、小型化工企业提出的。 相似文献
756.
757.
由郑州铁路局武汉客运分公司研发的LAJK-1型空调列车安全监控系统(俗称列车"黑匣子"),近日在武汉通地专家鉴定并装车试运行成功.自此,我国空调旅客列车有了保障安全的"黑匣子". 相似文献
758.
759.
Effects of temperature on UV-B-induced DNA damage and photorepair in Arabidopsis thaliana 总被引:2,自引:0,他引:2
DNA damage in the form of cyclobutane pyrimidine dimers(CPDs) and (6-4) photopreducts(6-4PPs) induced by UV-B radiation in Arabidopsis thaliana at different temperatures was investigated using ELISA with specific monoclonal antibodies. CPDs and 6-4PPs increased during 3 h UV-B exposure, but further exposure led to decreases. Contrary to the commonly accepted view that DNA damage induced by UV-B radiation is temperature-independent because of its photochemical nature, we found UV-B-induction of CPDs and 6-4PPs in Arabidopsis to be slower at a low than at a high temperature. Photorepair of CPDs at 24℃ was much faster than that at 0℃ and 12℃,with 50% CPDs removal during 1 h exposure to white light. Photorepair of 6-4PPs at 12℃ was very slow as compared with that at 24℃,and almost no removal of 6-4PPs was detected after 4 h exposure to white light at 0℃. There was evidence to suggest that temperaturedependent DNA damage and photorepair could have important ecological implications. 相似文献
760.
Growth and phosphate uptake kinetics of Microcystis aeruginosa under various environmental conditions 总被引:1,自引:0,他引:1
SHI Xiao-li YANG Liu-yan WANG Feng-ping XIAO Lin JIANG Li-juan KONG Zhi-ming GAO Guang QIN Bo-qiang 《环境科学学报(英文版)》2004,16(2):288-292
Growth and uptake of exogenous phosphate by Microcystis aeruginosa in batch culture under different temperature, photoperiod, and turbulence were studied by the method of phosphate isotope tracer. Relatively high temperature, long photoperiod and strong turbulence increased the cell density of M. aeruginosa in these batch cultures. The initial rapid uptake of phosphate by M. aeruginosa was independent of the temperature, photoperiod, and turbulence. Similarly, maximum exogenous phosphate uptake was not related to these environmental factors. However, elevated temperature and turbulence shortened the time, required to obtain maximum P accumulation. The growth of M. aeruginosa could alleviate the phosphorous leakage. Total amounts of exogenous phosphate uptake to M. aeruginosa and the phosphorus leakage of M. aeruginosa were significantly influenced by the growth state of M. aeruginosa closely correlated with the environmental factors. The maximum volume of exogenous phosphate uptake to M. aeruginosa was 46% of added exogenous phosphate in water with 16 hours of photoperiod. Thus, total amounts of exogenous phosphate uptake to M. aeruginosa were more strongly affected by the photoperiod length than temperature and turbulence. 相似文献