全文获取类型
收费全文 | 14625篇 |
免费 | 1561篇 |
国内免费 | 2792篇 |
专业分类
18978篇 |
出版年
2024年 | 65篇 |
2023年 | 301篇 |
2022年 | 556篇 |
2021年 | 767篇 |
2020年 | 575篇 |
2019年 | 783篇 |
2018年 | 692篇 |
2017年 | 574篇 |
2016年 | 703篇 |
2015年 | 982篇 |
2014年 | 1172篇 |
2013年 | 1215篇 |
2012年 | 1448篇 |
2011年 | 1332篇 |
2010年 | 889篇 |
2009年 | 828篇 |
2008年 | 937篇 |
2007年 | 836篇 |
2006年 | 755篇 |
2005年 | 621篇 |
2004年 | 530篇 |
2003年 | 460篇 |
2002年 | 411篇 |
2001年 | 268篇 |
2000年 | 212篇 |
1999年 | 178篇 |
1998年 | 135篇 |
1997年 | 102篇 |
1996年 | 80篇 |
1995年 | 49篇 |
1994年 | 56篇 |
1993年 | 38篇 |
1992年 | 52篇 |
1991年 | 46篇 |
1990年 | 56篇 |
1989年 | 38篇 |
1988年 | 20篇 |
1987年 | 20篇 |
1986年 | 30篇 |
1985年 | 19篇 |
1984年 | 19篇 |
1983年 | 21篇 |
1982年 | 13篇 |
1981年 | 14篇 |
1980年 | 8篇 |
1979年 | 18篇 |
1978年 | 6篇 |
1977年 | 9篇 |
1976年 | 9篇 |
1975年 | 7篇 |
排序方式: 共有10000条查询结果,搜索用时 7 毫秒
1.
2.
3.
4.
Correlation between bilayer destabilization and activity enhancement by diacylglycerols in reconstituted Ca-ATPase vesicles 总被引:1,自引:0,他引:1
Using the reconstituted Ca-ATPase vesicles as a model system, we demonstrated that the presence of 1,2-dioleoyl-sn-glycerol (diolein) in the membrane introduces a pronounced enhancement in the Ca-transport function of Ca-ATPase, while the 1,2-dipalmitoyl-sn-glycerol (dipalmitin) does not. We also found by both 31P NMR and freeze-fraction electron microscopy that diolein destabilized lipid bilayers to a greater extent than did dipalmitin. We conclude that the tendency of diacylglycerols to destabilize the phospholipid bilayer is related to their capacity to enhance the activity of the membrane calcium pump. 相似文献
5.
6.
7.
QIAN‐WAN MENG YI‐BO LUO 《Botanical journal of the Linnean Society. Linnean Society of London》2008,158(4):689-695
A new species, Galearis huanglongensis Q.W.Meng & Y.B.Luo, is described and illustrated. It is similar to Galearis cyclochila (Franch. & Sav.) Soó and Galearis diantha (Schltr.) P.F.Hunt, but differs in having a short spur, two elliptical lateral stigma lobes and distinctly separated bursicles. This new species is known only from the type locality, the Huanglong Valley, Songpan County, western Sichuan, China, growing amongst mosses under alpine shrubs at an elevation of about 3000 m. Based on two years of observations of its population size, the species was categorized as critically endangered CR (B1a, B2a) according to the World Conservation Union (IUCN) Red List Categories and Criteria, Version 3.1. The micromorphology of pollinia and seeds was observed by scanning electron microscopy and compared with that of G. cyclochila and G. diantha. The results supported G. huanglongensis Q.W.Meng & Y.B.Luo as a new species. © 2008 The Linnean Society of London, Botanical Journal of the Linnean Society, 2008, 158 , 689–695. 相似文献
8.
Yang Su-Rong Sun Huan-Xin Hu Zhen-Zhen Wang Si-Heng Sun Hui Xue Yin-Jia Ye Chen-Bo 《Sleep and biological rhythms》2017,15(1):57-65
Sleep and Biological Rhythms - Chronic sleep deprivation (SD) is an overwhelming problem in young students. Firstly, we investigated whether different levels of pre-training SD had effects on... 相似文献
9.
<正>Nanozymes, nanomaterials with enzyme-like characteristics,are emerging as novel artificial enzymes (Gao et al., 2007;Manea et al., 2004; Yan, 2018). They are superior to natural enzymes in many ways, such as higher stability, lower cost in preparation, and better robustness toward harsh environments (Wei and Wang, 2013). Various nanomaterials (e.g., 相似文献
10.
A neutral cholesterol esterase has been purified to homogeneity from the cytosolic fraction of rat liver. The 105,000 x g supernatant fraction of rat liver was applied to a DEAE-cellulose column to isolate a partially purified fraction of hepatic cholesterol esterase. Immunoblot analysis of the partially purified liver fraction with the anti-porcine pancreatic cholesterol esterase IgG demonstrated a single band with a molecular weight of 67,000. The hepatic protein was then isolated by immunoaffinity chromatography technique using a column constructed with antibodies prepared against the pancreatic cholesterol esterase. Characterization of the hepatic cholesterol esterase revealed that the hepatic enzyme shared antigenic epitopes with the pancreatic cholesterol esterase and was similarly activated by addition of bile salt such as taurocholate. Moreover, amino-terminal sequencing analysis of the hepatic cholesterol esterase showed an identical sequence with the pancreatic enzyme. Taken together, these results showed that the cholesterol esterases in the liver and the pancreas are very similar and possibly identical proteins. 相似文献