全文获取类型
收费全文 | 14501篇 |
免费 | 783篇 |
国内免费 | 8篇 |
出版年
2022年 | 38篇 |
2021年 | 119篇 |
2020年 | 62篇 |
2019年 | 90篇 |
2018年 | 149篇 |
2017年 | 156篇 |
2016年 | 255篇 |
2015年 | 394篇 |
2014年 | 458篇 |
2013年 | 1228篇 |
2012年 | 801篇 |
2011年 | 861篇 |
2010年 | 501篇 |
2009年 | 482篇 |
2008年 | 806篇 |
2007年 | 906篇 |
2006年 | 885篇 |
2005年 | 931篇 |
2004年 | 1015篇 |
2003年 | 941篇 |
2002年 | 885篇 |
2001年 | 168篇 |
2000年 | 137篇 |
1999年 | 178篇 |
1998年 | 230篇 |
1997年 | 213篇 |
1996年 | 185篇 |
1995年 | 154篇 |
1994年 | 117篇 |
1993年 | 161篇 |
1992年 | 139篇 |
1991年 | 105篇 |
1990年 | 106篇 |
1989年 | 102篇 |
1988年 | 103篇 |
1987年 | 80篇 |
1986年 | 83篇 |
1985年 | 91篇 |
1984年 | 106篇 |
1983年 | 90篇 |
1982年 | 109篇 |
1981年 | 103篇 |
1980年 | 92篇 |
1979年 | 48篇 |
1978年 | 57篇 |
1977年 | 51篇 |
1976年 | 56篇 |
1975年 | 28篇 |
1974年 | 39篇 |
1973年 | 40篇 |
排序方式: 共有10000条查询结果,搜索用时 62 毫秒
21.
Tuneyoshi Omori Yuji Inaba Tomiaki Morimoto Yoshio Tanaka Hiroshi Kurogi Minoru Matumoto 《Microbiology and immunology》1967,11(2):133-142
Five strains of bovine diarrhea virus were isolated from Japanese cattle using bovine tissue cultures. These are the first isolations of this virus from Japanese cattle to be reported. Of importance is the finding that the new isolates, which are non-cytopathogenic, induce an exaltation of Newcastle disease virus in bovine testicular cell culture. This finding has provided a laboratory tool whereby the assay of the virus and its neutralizing antibody can readily be performed. 相似文献
22.
Hiroshi Monoi 《生物化学与生物物理学报:生物膜》1982,693(1):159-164
An electrostatic calculation suggests that when an ion is bound near the mouth of a channel penetrating a low-dielectric membrane, a counter ion may form an ion pair with this ion. The tendency towards ion-pair formation is remarkably enhanced at channel mouths by forces (image forces) arising from the charges induced on the boundaries between different dielectrics. The binding constant for the formation of ion-pairs of monovalent ions is estimated under the assumption that local interactions between the counter ion and the channel wall are negligibly small. It is of the order of 1–10 molal?1 or more for the binding of a Cl? (F?) counter ion to an () ion if appropriate conditions are fulfilled. The binding constant depends on the position of the binding site, the dimensions and geometries of the channel and channel mouth, and the state of ion loading of the channel, as well as the ionic species. The present results also indicate that when cation (anion) channels have anionic (cationic) groups as integrant parts of their channel walls, interactions between these charged groups and permeant ions are markedly enhanced by the image forces. 相似文献
23.
Haruhide Kawabe Hiroshi Naganawa Shinichi Kondo Hamao Umezawa Susumu Mitsuhashi 《Microbiology and immunology》1978,22(9):515-521
A clinical isolate of Staphylococcus aureus resistant to gentamicin, kanamycin and 3′,4′-dideoxykanamycin B contained two enzymes capable of inactivating gentamicin, i.e., an aminoglycoside 2″-phosphotransferase and aminoglycoside acetyltransferase. 相似文献
24.
25.
A possible metabolic activation pathway of benzenein vivo is the nonenzymatic oxidation of hydroquinone producedvia the cytochrome P-450-mediate two-step oxidation of benzene. The mechanism of the further oxidation of hydroquinone and the nature of the most reactive intermediate have not yet been clarified, although it is speculated that the intermediate isp-benzoquinone and/orp-benzosemiquinone. The theoretical result of using molecular orbital calculations (ab initio and CNDO/2 methods) indicates that although the mechanism of the nonenzymatic oxidation of hydroquinone cannot yet be determined, the intermediate is thep-benzosemiquinone anion radical. It is also suggested that active-oxygen species such as hydroxyl radical, which accelerates the nonenzymatic oxidation, play an important role in the metabolic pathway in question. 相似文献
26.
Summary An activated carbon column was utilized for the synthesis of disaccharides by use of a reversed hydrolysis activity of an immobilized -galactosidase column in order to shift the equilibrium to the direction of condensation. The yields of lactulose and allo-lactulose from galactose and fructose, and N-acetyl lactosamine and N-acetyl allolactosamine from galactose and N-acetyl glucosamine, were 11.3% and 10.0%, respectively. 相似文献
27.
Summary
E.
coli cells harbouring plasmid pBR322 which confers ampicillin resistance were immobilized on cotton cloth. The resulting film was used as an inoculum in daily repeated batch culture in ampicillin-free medium. During two months, the film was able to produce cultures which, at the late log phase, showed little sensitivity to 10 mg/ml ampicillin. Thus such a bacterial film can effectively be used as an inoculum for the production of recombinant DNA products by means of pBR322 or its derivatives in the absence of ampicillin. 相似文献
28.
Biosynthesis of Purine Alkaloids in Camellia Plants 总被引:2,自引:0,他引:2
The metabolism of [8-14C]adenine and [8-14C]hypoxanthine infour species of Camellia plants was investigated in relationto the synthesis of purine alkaloids, caffeine and theobromine.Young leaves of C. sinensis had the ability to synthesize caffeine,but in C. irrawadiensis, these labelled precursors were incorporatedinto theobromine, not caffeine. No synthesis of purine alkaloidscould be detected in C. japonica and C. sasanqua leaves. Conventional"salvage" and degradation pathways of purines were present inall species of Camellia plants examined.
1 Present address: Research Center, Mitsubishi Chemical IndustriesLtd., 1000 Kamisida-cho, Midori-ku, Yokohama, 227 Japan. (Received September 29, 1986; Accepted January 22, 1987) 相似文献
29.
Koichi Suzuki Shinobu Imajoh Yasufumi Emori Hiroshi Kawasaki Yasufumi Minami Shigeo Ohno 《FEBS letters》1987,220(2):271-277
The structures of calcium-activated neutral protease (CANP) and its endogenous inhibitor elucidated recently have revealed novel features with respect to their structure-function relationship and enzyme activity regulation. The protease is regarded as a proenzyme which can be activated at the cell membrane in the presence of Ca2+ and phospholipid, and presumably regulates the functions of proteins, especially membrane-associated proteins, by limited proteolysis. Protein kinase C is hydrolysed and activated by CANP at the cell membrane to a cofactor-independent form. These results are reviewed and the possible involvement of CANP in signal transduction is discussed. 相似文献
30.