全文获取类型
收费全文 | 73552篇 |
免费 | 3440篇 |
国内免费 | 6504篇 |
出版年
2023年 | 864篇 |
2022年 | 1030篇 |
2021年 | 1627篇 |
2020年 | 1669篇 |
2019年 | 2099篇 |
2018年 | 1864篇 |
2017年 | 1682篇 |
2016年 | 1742篇 |
2015年 | 1933篇 |
2014年 | 3305篇 |
2013年 | 5216篇 |
2012年 | 2738篇 |
2011年 | 3453篇 |
2010年 | 2722篇 |
2009年 | 3521篇 |
2008年 | 3846篇 |
2007年 | 3957篇 |
2006年 | 3705篇 |
2005年 | 3497篇 |
2004年 | 3039篇 |
2003年 | 2896篇 |
2002年 | 2541篇 |
2001年 | 2072篇 |
2000年 | 1771篇 |
1999年 | 1656篇 |
1998年 | 1569篇 |
1997年 | 1393篇 |
1996年 | 1378篇 |
1995年 | 1298篇 |
1994年 | 1280篇 |
1993年 | 1035篇 |
1992年 | 945篇 |
1991年 | 813篇 |
1990年 | 725篇 |
1989年 | 640篇 |
1988年 | 609篇 |
1987年 | 602篇 |
1986年 | 425篇 |
1985年 | 753篇 |
1984年 | 1022篇 |
1983年 | 680篇 |
1982年 | 780篇 |
1981年 | 599篇 |
1980年 | 535篇 |
1979年 | 463篇 |
1978年 | 295篇 |
1977年 | 281篇 |
1976年 | 239篇 |
1974年 | 189篇 |
1973年 | 180篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
101.
A possibly physiologically significant inhibition of yeast enolase by fluoride occurs in the absence of inorganic phosphate. The inhibition increases with time, is strongly dependent on fluoride concentration and requires substrate and “catalytic” Mg2+. The inhibition increases more slowly in the presence of product (phosphoenolpyruvate) than substrate (2-phosphoglycerate). The dependence on fluoride concentration and the spans of substrate analogue displacement titrations suggest the inhibition is produced by two moles of fluoride per active site. 相似文献
102.
103.
Shiro Tabata Takeshi Ide Yasuyoshi Umemura Kenzo Torri 《Biochimica et Biophysica Acta (BBA)/General Subjects》1984,797(2):231-238
α-Glucosidases or maltases (EC 3.2.1.20) were purified to electrophoretic homogeneity from a respective strain of Sacchromyces cerevisiae which carries a single MAL gene, either MALα, MALβ or MALγ, using gluconate-Sepharose affinity chromography and isoelectrofocusing. Of these maltases, two types of maltase were obtained from the MALγ strain, the pI values of which were 5.6 and 5.9. From the MALα and MALβ strain was obtained only one type of maltase with the pI at 5.6 which was identical to one of the maltases from the MALγ strain. These four maltases possessed the same properties, except for pI. They were monomers with molecular weights of between 66 000 and 67 000. With regard to the substrate specificity, they hydrolyzed maltose and sucrose exclusively but not α-methulglucoside nor maltooligosaccharide. They did not differ in immunological properties. 相似文献
104.
105.
106.
《Bioorganic & medicinal chemistry letters》2020,30(16):127289
The present research project details synthesis of new hybrid methanofullerenes based on acetylene and triazole esters of malonic acid containing 5Z,9Z-dienoic acids and fullerene C60 under Bingel-Hirsch conditions, including study of the cytotoxic activity with respect to Jurkat, K562, U937 and HL60 tumor cell lines. Hybrid methanofullerenes containing acetylenic fragments, unlike triazole substituents, were found to exhibit higher cytotoxicity, but are characterized by lower selectivity of action in relation to healthy cells. 相似文献
107.
108.
Robert J. Pryce 《Phytochemistry》1973,12(7):1745-1754
Allogibberic acid (I) has been identified as the compound responsible for the inhibition of flowering, increase in frond multiplication rate and decrease in frond size produced in Lemna perpusilla 6746 by autoclaved, unbuffered aqueous solutions of gibberellic acid (VII). 13-Deoxyallogibberic acid (IV), a product of autoclaving aq. GA7 (VIII) solutions, also inhibits flowering in L. perpusilla and is about 10 times more active than allogibberic acid. 相似文献
109.
110.