全文获取类型
收费全文 | 723篇 |
免费 | 52篇 |
出版年
2024年 | 1篇 |
2023年 | 25篇 |
2022年 | 10篇 |
2021年 | 23篇 |
2020年 | 22篇 |
2019年 | 17篇 |
2018年 | 38篇 |
2017年 | 36篇 |
2016年 | 44篇 |
2015年 | 34篇 |
2014年 | 48篇 |
2013年 | 107篇 |
2012年 | 53篇 |
2011年 | 54篇 |
2010年 | 50篇 |
2009年 | 40篇 |
2008年 | 23篇 |
2007年 | 22篇 |
2006年 | 26篇 |
2005年 | 15篇 |
2004年 | 16篇 |
2003年 | 7篇 |
2002年 | 7篇 |
2001年 | 8篇 |
2000年 | 7篇 |
1999年 | 11篇 |
1998年 | 2篇 |
1997年 | 3篇 |
1996年 | 5篇 |
1994年 | 1篇 |
1993年 | 1篇 |
1992年 | 6篇 |
1991年 | 2篇 |
1990年 | 2篇 |
1989年 | 1篇 |
1985年 | 1篇 |
1984年 | 1篇 |
1980年 | 2篇 |
1976年 | 2篇 |
1972年 | 1篇 |
1971年 | 1篇 |
排序方式: 共有775条查询结果,搜索用时 15 毫秒
771.
We investigated the reactions of substituted aryl radicals and aryl cations derived from arenediazonium ions and their ability to cause cleavage of supercoiled DNA and their tendency toward free radical or cation formation in the presence and absent of copper (I) chloride. It was found that the substituted arenediazonium salts can cleave supercoiled DNA to the open circular form II DNA and linear form III DNA. Results methodical studies indicate that both carbon-centered radicals and aryl cations participate in the cleavage pathways. 相似文献
772.
773.
Dicle Çevik Suat Erdogan Riza Serttas Yüksel Kan Hasan Kırmızıbekmez 《化学与生物多样性》2023,20(1):e202200589
Cytotoxic activity-guided fractionation studies on Glycyrrhiza echinata roots led to the isolation of eight compounds ( 1 – 8 ). Chemical structures of the isolates were identified by NMR and MS analysis. Among the tested molecules, retrochalcones namely echinatin ( 3 ) (IC50=23.45–41.83 μM), licochalcone B ( 4 ) (IC50=36.04–39.53 μM) and tetrahydroxylmethoxychalcone ( 5 ) (IC50=7.09–80.81 μM) were the most active ones against PC3, MCF7 and HepG2 cells. Moreover, 5 exhibited selectivity on prostate cancer cells (SI: 5.19). Hoechst staining and Annexin V/PI binding assays as well as cell cycle analysis on the compounds 3 (23 μM) and 5 (5 and 7 μM) demonstrated that these retrochalcones induced apoptosis and significantly suppressed cell cycle in G1 and G2/M phases. Furthermore, 3 and 5 showed antimigratory effects on PC3 cells by wound healing assay. The results indicated that tested retrochalcones most particularly 5 could be potential anticancer drug candidates that prevent proliferation and migration of cancer cells. 相似文献
774.
775.
Experimental assessment of the hydrolysis rate coefficients for both domestic sewage and a number of industrial wastewaters was performed with emphasis on two different hydrolysis mechanisms associated with the readily and slowly hydrolyzable COD fractions. The adopted dual hydrolysis model was justified on the basis of significantly different rate constants. The hydrolysis rate of particulate COD occurred at such a slow rate that would significantly interfere with endogenous decay. © Rapid Science Ltd. 1998 相似文献