全文获取类型
收费全文 | 4609篇 |
免费 | 277篇 |
国内免费 | 2篇 |
出版年
2022年 | 29篇 |
2021年 | 46篇 |
2020年 | 33篇 |
2019年 | 35篇 |
2018年 | 33篇 |
2017年 | 49篇 |
2016年 | 74篇 |
2015年 | 104篇 |
2014年 | 132篇 |
2013年 | 310篇 |
2012年 | 234篇 |
2011年 | 241篇 |
2010年 | 164篇 |
2009年 | 118篇 |
2008年 | 221篇 |
2007年 | 222篇 |
2006年 | 231篇 |
2005年 | 225篇 |
2004年 | 215篇 |
2003年 | 244篇 |
2002年 | 266篇 |
2001年 | 138篇 |
2000年 | 120篇 |
1999年 | 113篇 |
1998年 | 82篇 |
1997年 | 49篇 |
1996年 | 47篇 |
1995年 | 41篇 |
1994年 | 59篇 |
1993年 | 37篇 |
1992年 | 69篇 |
1991年 | 93篇 |
1990年 | 80篇 |
1989年 | 83篇 |
1988年 | 48篇 |
1987年 | 60篇 |
1986年 | 48篇 |
1985年 | 46篇 |
1984年 | 41篇 |
1983年 | 29篇 |
1982年 | 36篇 |
1981年 | 36篇 |
1980年 | 34篇 |
1979年 | 28篇 |
1978年 | 23篇 |
1977年 | 21篇 |
1976年 | 26篇 |
1974年 | 21篇 |
1973年 | 22篇 |
1971年 | 21篇 |
排序方式: 共有4888条查询结果,搜索用时 15 毫秒
61.
Ichiro Oohara Akira Suyama Akiyoshi Wada 《Biochimica et Biophysica Acta (BBA) - Gene Structure and Expression》1983,741(3)
Poly(l-glutamic acid) has been reported to mediate in vitro nucleosome assembly (Stein, A., Whitlock, J.P., Jr. and Bina, M. (1979) Proc. Natl. Acad. Sci. U.S.A. 76, 5000–5004). To study the reaction mechanism, we have reconstituted nucleosome core particles from chicken erythrocyte core DNA and core histones in the presence of poly(l-glutamic acid) and analyzed the assembly products by polyacrylamide gel electrophoresis. Poly(l-glutamic acid), which binds and forms a large complex with core histones, is replaced with core DNA in the reconstitution process. When histone-poly(l-glutamic acid) complex and core DNA are mixed with a histone:DNA ratio of 1.0, the yield of core particles increases by prolonged reconstitution time. Two phases with a distinct time range appear in the process. In the fast phase within 30 min, 60% of the DNA is involved in products containing histones: reconstituted core particles, a larger nucleoprotein complex and aggregation. In the second phase, the remaining DNA and the DNA in the aggregation decrease, and the core particles increase slowly. The yield of core particles is approx. 60% after 24 h. The slow phase is not observed by reconstitution with a histone:DNA ratio of 2.0 in the initial mixture. The reaction scheme of the assembly process derived from these data is given. Based on the in vitro reaction scheme, the possible role of in vivo ‘nucleosome assembly factors’ is also discussed. 相似文献
62.
Raman diagnosis of nucleic acid structure: sugar-puckering and glycosidic conformation in the guanosine moiety. 总被引:6,自引:6,他引:0
下载免费PDF全文
![点击此处可从《Nucleic acids research》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Y Nishimura M Tsuboi T Nakano S Higuchi T Sato T Shida S Uesugi E Ohtsuka M Ikehara 《Nucleic acids research》1983,11(5):1579-1588
Observations of Raman spectra of various nucleic acids indicate that the guanine ring breathing frequency is sensitive to the internal rotation angle around the glycosidic bond and to the conformation of the five-membered ring of the ribose residue that is directly connected with the guanine residue in question. It is found that 682 cm-1 for C2'-endo-anti, at 665 cm-1 for C3'-endo-anti, and at 625 cm-1 for C3'-endo-syn. A DNA octamer d(GpGpApApTpTpCpC) shows, in its aqueous solution, a broad Raman band at 680 cm-1 with a tail at 670 cm-1. This fact suggests that the guanosine residues in this oligomer take primarily C2'-endo-anti conformation but an appreciable amount of fluctuation of the ribose ring structure towards C3'-endo is involved. 相似文献
63.
Metabolism of -methylmalic acid by a soil bacterium 总被引:1,自引:0,他引:1
64.
Harry Brumberger Jeffrey L. Lipton Gary Dorfman Eileen Nakano 《The Biochemical journal》1974,143(2):495-496
Small-angle X-ray scattering measurements on native pig thyroglobulin in phosphate buffer, pH6.9, yield a radius of gyration of 6.4nm (64Å), a particle volume of approx. 1.5×103nm3 (1.5×106Å3), an axial ratio of 2.2:1 (assuming an ellipsoidal shape), and a solvation of 0.63g of solvent/g of protein. 相似文献
65.
66.
Tetsuya Tosa Tadashi Sato Takao Mori Yuhsi Matuo Ichiro Chibata 《Biotechnology and bioengineering》1973,15(1):69-84
Various methods were tried for the immobilization of aspartase, and the preparation having the highest activity was obtained when partially purified aspartase from Escherichia coli was entrapped into polyacrylamide gel Iattice. Enzymatic properties of the immobilized aspartase were investigated and compared with those of the native aspartase. With regard to optimum pH, temperature, concentration of Mn++, kinetic constants and heat stability, no marked difference was observed between the native and immobilized aspartases. By employing an enzyme column packed with the immobilized aspartase, conditions for continuous production of L -aspartic acid from ammonium fumarate were investigated. When a solution of 1M ammonium fumarate (pH 8.5, containing 1mM MnCl2) was passed through the aspartase column at the flow rate of SV = 0.08 at 37°C, the highest rate of reaction was attained. From the column effluents, L-aspartic acid was obtained in a good yield. 相似文献
67.
68.
69.
Effect of dihydroergotamine and propranolol on dibutyryl cyclic 3',5'-AMP-induced lipolysis in isolated rat fat cells 总被引:1,自引:0,他引:1
70.