全文获取类型
收费全文 | 13727篇 |
免费 | 700篇 |
国内免费 | 8篇 |
专业分类
14435篇 |
出版年
2023年 | 27篇 |
2022年 | 65篇 |
2021年 | 113篇 |
2020年 | 58篇 |
2019年 | 85篇 |
2018年 | 139篇 |
2017年 | 146篇 |
2016年 | 245篇 |
2015年 | 375篇 |
2014年 | 432篇 |
2013年 | 1138篇 |
2012年 | 764篇 |
2011年 | 826篇 |
2010年 | 481篇 |
2009年 | 462篇 |
2008年 | 778篇 |
2007年 | 864篇 |
2006年 | 853篇 |
2005年 | 889篇 |
2004年 | 972篇 |
2003年 | 907篇 |
2002年 | 856篇 |
2001年 | 140篇 |
2000年 | 99篇 |
1999年 | 144篇 |
1998年 | 220篇 |
1997年 | 206篇 |
1996年 | 169篇 |
1995年 | 145篇 |
1994年 | 114篇 |
1993年 | 153篇 |
1992年 | 126篇 |
1991年 | 91篇 |
1990年 | 90篇 |
1989年 | 88篇 |
1988年 | 85篇 |
1987年 | 64篇 |
1986年 | 74篇 |
1985年 | 88篇 |
1984年 | 100篇 |
1983年 | 87篇 |
1982年 | 106篇 |
1981年 | 95篇 |
1980年 | 83篇 |
1979年 | 41篇 |
1978年 | 47篇 |
1977年 | 43篇 |
1976年 | 51篇 |
1974年 | 36篇 |
1973年 | 33篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
131.
132.
Hiroshi Yamamoto Hiroshi Okamoto 《Biochemical and biophysical research communications》1980,95(1):474-481
Picolinamide, 2-pyridinecarboxylic acid amide, was found to be a strong inhibitor of poly (ADP-ribose) synthetase of nuclei from rat pancreatic islet cells. Another experiment using isolated pancreatic islets of rats showed that picolinamide protects against streptozotocin-induced depression of proinsulin synthesis as well as against streptozotocin-induced reduction of NAD content. The protection by picolinamide against the NAD depression was considered to be due to the blockage of an increased degradation of NAD mediated by a streptozotocin-induced increase in poly (ADP-ribose) synthetase activity. A possible mechanism of streptozotocin diabetes and its prevention is discussed. 相似文献
133.
Elisabetta Colletti Laura Frontali Claudio Palleschi Micheline Wesolowski Hiroshi Fukuhara 《Molecular & general genetics : MGG》1979,175(1):1-4
Summary In S. cerevisiae four isoacceptor mitochondrial tRNAs for serine have been separated by reversed phase chromatography. At least two of these species are products of different genes. In this work the deletion mapping technique has been used to locate two genes for tRNAser. The gene for tRNAser previously localized in the oli I region of the mitochondrial genome has been found to code for tRNA
ser
2
, and another gene coding for tRNA
ser
1
has been detected in the region where most of other tRNA genes are found. Results of fine mapping experiments allowed to localize this gene in the proximity of the gene for tRNAarg. 相似文献
134.
The dry weight and glucosamine content of the alkali-insoluble"rigid wall" of Chlorella ellipsoidea were measured in synchronouslygrowing and dividing cells. The content of glucosamine, the major component of the rigidwall, was measured by the Elson-Morgan and the ninhydrin reactions.The results revealed, in agreement with previous observations,that the amount of the rigid wall, measured in terms of wholedry weight or glucosamine content, remains almost constant duringthe growing phase and increases only in the reproduction phase. (Received February 19, 1979; ) 相似文献
135.
Changes in the pattern of soluble proteins that accumulatedat the growth phase, interphase and late-aggregation phase ofthe cellular slime mold Dictyostelium discoideum were studiedby two-dimensional polyacrylamide gel electrophoresis. Amongthe 300 proteins detected during the early development, themost soluble do not change during the growth and aggregationphases, but about 90 proteins show changes in their relativeintensities on staining. During the transition from growth tothe interphase, the predominant changes were the disappearanceof 16 spots, the decrease in 30 spots, the appearance of 13new spots, and the increase in 14 spots. In contrast, from theinterphase to the late-aggregation phase, there were remarkableprogressive increases in 13 spots, an overall increase in 6spots, a decrease in 16 spots, the appearance of 8 new spotsand the disappearance of 4 spots. (Received July 13, 1979; ) 相似文献
136.
137.
Protein I of Neisseria gonorrhoeae outer membrane is a porin 总被引:2,自引:1,他引:1
138.
Hiroshi Hitokoto Satoshi Morozumi Tomoaki Wauke Senzo Sakai Hiroshi Kurata 《Mycopathologia》1981,73(1):33-38
A total of 604 samples of about 7 different types of beans was examined to determine their mycological profiles, and suitability for use as solid substrates for mycotoxin production.All of the samples were collected from bean jam makers in Tokyo by the official food examiners.Genera Penicillium and Aspergillus were predominant, and genus Wallemia was also found commonly in all types of beans.Mycotoxin-producing Aspergillus strains were isolated from 52 samples of beans, approximately 9% of the total. The highest incidence of toxigenic Aspergillus (14.1%) was found in kidney beans. Red beans and peas inoculated with Aspergillus ochraceus were found to produce about 7 to 8 times more toxin than was obtained in a liquid medium, and red beans inoculated with A. versicolor produced more toxin than was obtained in yeast extract sucrose broth. Green peas inoculated with Fusarium graminearum produced about 8 times more T-2 toxin than was obtained in 1% peptone containing Czapek solution under comparable culture conditions. 相似文献
139.
The liberation of 2,4-dinitrophenolate ion from 2,4-dinitrophenyl sulfate (DNPS) in aqueous organic solvent with 0.1 N sodium hydroxide was accelerated upon addition of an equimolar amount of Oxime-I (10-hydroxy-11-hydroxyimino[20]-paracyclophane) to the sulfate ester. Oxime-I was found to undergo covalent participation at the oxime group to afford oxime O-sulfonate. The rate acceleration with Oxime-I was larger than that with β-CD (cycloheptaamylose). The catalytic efficiency of Oxime-I has been ascribed primarily to the tighter inclusion of the substrate ester into the more hydrophobic Oxime-I cavity provided by the effective apolar paracyclophane skeleton, as well as to the greater nucleophilicity of the oxime group than of the hydroxyl group in β-CD. Consequently, Oxime-I may be considered as a conventional model for arylsulfatases and sulfotransferases, providing the effective binding process for the substrate. 相似文献
140.
The relationship between temperature and 2,6-dichlorophenolindophenol(DPIP) photoreduction activity in chloroplast fragments isolatedfrom spinach grown at different temperatures was investigatedin the temperature range from 25 to 25?C. Two break points in the slope of the Arrhenius plot of the Hillreaction were observed at 9 and 11?C in chloroplast fragmentsisolated from spinach grown at low temperatures (010?C).These breaks were not affected by an uncoupler. In chloroplastfragments from spinach grown in a higher temperature range (1030?C),only one break point was observed at 9?C. The other breakpoint at around 10?C appeared after treatment with detergent.Both break points were completely abolished by fixing the chloroplastfragments with glutaraldehyde. The break at around 10?C in chloroplast fragments isolated fromspinach grown at lower temperature was interpreted as due toacclimation rather than chilling sensitivity. (Received September 6, 1977; ) 相似文献