全文获取类型
收费全文 | 14093篇 |
免费 | 1201篇 |
国内免费 | 10篇 |
出版年
2022年 | 118篇 |
2021年 | 235篇 |
2020年 | 145篇 |
2019年 | 189篇 |
2018年 | 211篇 |
2017年 | 174篇 |
2016年 | 340篇 |
2015年 | 593篇 |
2014年 | 609篇 |
2013年 | 821篇 |
2012年 | 989篇 |
2011年 | 1003篇 |
2010年 | 649篇 |
2009年 | 572篇 |
2008年 | 863篇 |
2007年 | 898篇 |
2006年 | 815篇 |
2005年 | 766篇 |
2004年 | 794篇 |
2003年 | 739篇 |
2002年 | 686篇 |
2001年 | 162篇 |
2000年 | 115篇 |
1999年 | 163篇 |
1998年 | 175篇 |
1997年 | 130篇 |
1996年 | 122篇 |
1995年 | 112篇 |
1994年 | 100篇 |
1993年 | 114篇 |
1992年 | 118篇 |
1991年 | 79篇 |
1990年 | 91篇 |
1989年 | 73篇 |
1988年 | 81篇 |
1987年 | 85篇 |
1986年 | 62篇 |
1985年 | 85篇 |
1984年 | 93篇 |
1983年 | 81篇 |
1982年 | 107篇 |
1981年 | 97篇 |
1980年 | 90篇 |
1979年 | 57篇 |
1978年 | 52篇 |
1977年 | 63篇 |
1976年 | 58篇 |
1975年 | 48篇 |
1974年 | 54篇 |
1973年 | 60篇 |
排序方式: 共有10000条查询结果,搜索用时 62 毫秒
91.
92.
Changes in certain kinetic properties of hepatic microsomal aniline hydroxylase and ethylmorphine demethylase associated with postnatal development and maturation in male rats 总被引:2,自引:2,他引:0 下载免费PDF全文
Theodore E. Gram Anthony M. Guarino David H. Schroeder James R. Gillette 《The Biochemical journal》1969,113(4):681-685
1. Changes in certain kinetic properties (V(max.) and apparent K(m)) of hepatic microsomal mixed-function oxidases have been studied as a function of postnatal development and maturation in male rats. 2. Microsomal cytochrome P-450 content changed only slightly between 1 and 12 weeks of age. 3. Aniline hydroxylase activity (V(max.)) increased abruptly between 1 and 2 weeks of age to greater than adult activities and then returned to a plateau value between 4(1/2) and 12 weeks of age. Ethylmorphine demethylase activity remained low and relatively constant between 1 and 3 weeks of age and then increased markedly ( approximately 100%) between 3 and 4(1/2) weeks. 4. The apparent Michaelis constant (K(m)) for aniline hydroxylation increased almost linearly with time between 1 and 6 weeks of age and tended to reach a plateau value thereafter. The apparent K(m) for ethylmorphine demethylation increased between 1 and 3 weeks of age and then decreased abruptly to a constant value between 6 and 12 weeks. 5. The data indicate that developmental changes in the activity of these microsomal oxidases do not correlate temporally with each other or with changes in microsomal cytochrome P-450 content. 6. The most dramatic changes in enzyme activity were associated with early development (1-3 weeks) and weaning (3-4 weeks). 7. Changes in weight of seminal vesicle, a criterion of sexual maturation in male rats, were most prominent between 6 and 8 weeks of age and thus appeared to be separated in time from the prominent changes in enzyme activity. 相似文献
93.
Anthony J. Hedley Anne M. Scott R. Deans Weir James Crooks 《BMJ (Clinical research ed.)》1970,1(5695):556-558
An automated follow-up register for the detection of iatrogenic thyroid disease has been established as a joint venture between the general practitioners in the north-east of Scotland and the thyroid clinic of Aberdeen General Hospitals.The data-processing operations in the system are handled by an International Computers Limited 4/50 computer. Patients are followed up at predetermined intervals and the system has been designed to process, screen, and store clinical and biochemical follow-up data and report results to the patients, general practitioners, and the hospital records department. 相似文献
94.
A strain ofPseudomonas aeruginosa could be induced to oxidizen-paraffins and to epoxidize-olefins by treating peptone-grown cells with 1,6-hexanediol or by growing them on this substrate. Of some related alcohols and acids investigated, only a few showed weak inducing capacities.Shell Research N.V. 相似文献
95.
1. A sensitive fluorimetric procedure for the assay of d-amino acid oxidase has been developed. 2. The method depends on the formation of a fluorescent derivative, 2-hydroxy-3-methylquinoxaline, on condensation of pyruvate with o-phenylenediamine in acid medium. 3. 2-Hydroxy-3-methylquinoxaline fluoresces strongly in 50% (v/v) sulphuric acid after excitation at 375mmu. A single emission peak is observed at 480mmu. 4. Formation of the quinoxaline is dependent on time, temperature, acidity and relative concentration of reactants. 5. A particulate preparation from mouse kidney required FAD for optimum activity at pH8.5; K(m) was 3.8x10(-3)m; K(FAD) was 1.4x10(-7)m and the reaction was strongly inhibited by p-chloromercuribenzoate and phenylmercuric acetate. 6. Subcellular fractionation on a sucrose density gradient confirmed that the d-amino acid oxidase was localized on small granules. 相似文献
96.
Anthony Green 《BMJ (Clinical research ed.)》1964,2(5418):1200-1201
97.
Anthony F. Gaudy Jr. Richard S. Engelbrecht Ralph D. De Moss 《Applied microbiology》1960,8(5):298-304
98.
99.
Summary From a culture broth ofPseudomonas aeruginosa (KSLA strain 473) grown on heptane as the sole source of carbon, fatty acids could be isolated after a period of decreased
oxygen supply. The corresponding methyl esters—obtained by treatment with diazomethane—were separated by gas-liquid chromatography
and identified by mass spectrometry. Heptylic, valeric and propionic acids were shown to be present in the original culture
broth.
Using the same techniques the formation of caproic acid from hexane was shown to occur, whereas the amount of butyric acid
formed was extremely small and inconsistent.
These results show conclusively that this microbiological oxidation of heptane and hexane proceeds by way of the corresponding
fatty acids, which are further degraded by β-oxidation. The absence of caproic and valeric acids in heptane and hexane oxidation,
respectively, shows that decarboxylation of fatty acids does not occur. 相似文献
100.