全文获取类型
收费全文 | 521篇 |
免费 | 43篇 |
国内免费 | 192篇 |
专业分类
安全科学 | 8篇 |
环保管理 | 6篇 |
综合类 | 365篇 |
基础理论 | 294篇 |
污染及防治 | 59篇 |
评价与监测 | 18篇 |
社会与环境 | 5篇 |
灾害及防治 | 1篇 |
出版年
2024年 | 1篇 |
2023年 | 11篇 |
2022年 | 9篇 |
2021年 | 18篇 |
2020年 | 8篇 |
2019年 | 6篇 |
2018年 | 13篇 |
2017年 | 19篇 |
2016年 | 20篇 |
2015年 | 21篇 |
2014年 | 17篇 |
2013年 | 68篇 |
2012年 | 36篇 |
2011年 | 35篇 |
2010年 | 34篇 |
2009年 | 34篇 |
2008年 | 51篇 |
2007年 | 41篇 |
2006年 | 42篇 |
2005年 | 21篇 |
2004年 | 24篇 |
2003年 | 26篇 |
2002年 | 15篇 |
2001年 | 20篇 |
2000年 | 17篇 |
1999年 | 19篇 |
1998年 | 14篇 |
1997年 | 15篇 |
1996年 | 14篇 |
1995年 | 19篇 |
1994年 | 19篇 |
1993年 | 9篇 |
1992年 | 7篇 |
1991年 | 7篇 |
1990年 | 4篇 |
1989年 | 7篇 |
1988年 | 9篇 |
1987年 | 2篇 |
1986年 | 4篇 |
排序方式: 共有756条查询结果,搜索用时 15 毫秒
51.
1. The HGPRT (Hypoxanthine‐Guanine‐Phospho‐Ribosyl‐Transferase) assay with Chinese Hamster V79 cells was used to measure the mutagenic effects of UV irradiation, potassium dichromate and nickel chloride. The agents were tested separately and in the combinations of UV plus nickel and dichromate plus nickel. 2. UV, Cr(VI) and Ni(II) were confirmed to be mutagenic in the V79 cell assay. The combination of UV(5J/m2) and Ni(II) (0.5 mM) caused a mutation rate 11.2 times above that corresponding to the sum of the individual mutation rates of these agents. The combined action of Cr(VI) (0.1 mM) and Ni(II) (0.5 mM) produced a mutation rate 2.8 fold above that corresponding to the sum of the individual rates of the separate agents. 3. The enhancing effect of nickel chloride on the mutagenicity of UV or Cr(VI) is interpreted by an interference of Ni(II) with the repair of DNA lesions. 相似文献
52.
53.
G. Bronzetti A. Galli P. Boccardo R. Vellosi R. Del Carratore E. Sabbioni 《毒物与环境化学》2013,95(1-2):103-111
The genotoxicity of chromium chloride was investigated in cells of D7 strain of Saccharomyces cerevisiae harvested either from logarithmic or stationary growth phase. A weak induction of mifotic gene conversion and point reverse mutation was obtained when the incubations were performed using phosphate buffer. No genetic effect was observed when the incubations were performed using Tris‐HCl buffer. The experiments with 51Cr radiotracer demonstrated that Cr3+ ion enters the yeast cells and binds to DNA even if the incubation mixture was performed with Tris HCl buffer. This behaviour could be due to the highest concentration of CrCl3 that cause some damages to cytoplasmatic membrane. 相似文献
54.
Jay D. Evans 《Behavioral ecology and sociobiology》1996,39(4):275-284
In many polygynous ant species, established colonies adopt new queens secondarily. Conflicts over queen adoption might arise
between queens and workers of established colonies and the newly mated females seeking adoption into nests. Colony members
are predicted to base adoption decisions on their relatednesses to other participants, on competition between queens for colony
resources, and on the effects that adopted queens have on colony survivorship and productivity. To provide a better understanding
of queen-adoption dynamics in a facultatively polygynous ant, colonies of Myrmica tahoensis were observed in the field for 4 consecutive years and analyzed genetically using highly polymorphic microsatellite DNA markers.
The extreme rarity of newly founded colonies suggests that most newly mated queens that succeed do so by entering established
nests. Queens are closely related on average (rˉ = 0.58), although a sizable minority of queen pairs (29%) are not close relatives. An experiment involving transfers of queens
among nests showed that queens are often accepted by workers to which they are completely unrelated. Average queen numbers
estimated from nest excavations (harmonic mean = 1.4) are broadly similar to effective queen numbers inferred from the genetic
relatedness of colony members, suggesting that reproductive skew is low in this species. Queens appear to have reproductive
lifespans of only 1 or 2 years. As a result, queens transmit a substantial fraction of their genes posthumously (through the
reproduction of related nestmates), in comparison to direct and indirect reproduction while they are alive. Thus queens and
other colony members should often accept new queens when doing so will increase colony survivorship, in some cases even when
the adopted queens are not close relatives.
Received: 20 February 1996/Accepted after revision: 25 May 1996 相似文献
55.
56.
57.
58.
59.
60.