全文获取类型
收费全文 | 2625篇 |
免费 | 145篇 |
国内免费 | 58篇 |
出版年
2023年 | 36篇 |
2022年 | 20篇 |
2021年 | 30篇 |
2020年 | 50篇 |
2019年 | 68篇 |
2018年 | 52篇 |
2017年 | 45篇 |
2016年 | 50篇 |
2015年 | 50篇 |
2014年 | 106篇 |
2013年 | 124篇 |
2012年 | 76篇 |
2011年 | 87篇 |
2010年 | 69篇 |
2009年 | 91篇 |
2008年 | 96篇 |
2007年 | 119篇 |
2006年 | 88篇 |
2005年 | 102篇 |
2004年 | 99篇 |
2003年 | 87篇 |
2002年 | 71篇 |
2001年 | 91篇 |
2000年 | 83篇 |
1999年 | 66篇 |
1998年 | 52篇 |
1997年 | 35篇 |
1996年 | 37篇 |
1995年 | 39篇 |
1994年 | 50篇 |
1993年 | 52篇 |
1992年 | 32篇 |
1991年 | 31篇 |
1990年 | 29篇 |
1989年 | 24篇 |
1988年 | 36篇 |
1987年 | 32篇 |
1986年 | 24篇 |
1985年 | 33篇 |
1984年 | 43篇 |
1983年 | 56篇 |
1982年 | 64篇 |
1981年 | 51篇 |
1980年 | 43篇 |
1979年 | 35篇 |
1978年 | 33篇 |
1977年 | 25篇 |
1976年 | 30篇 |
1974年 | 26篇 |
1973年 | 20篇 |
排序方式: 共有2828条查询结果,搜索用时 15 毫秒
51.
52.
The asymptotic information in censored survival data 总被引:2,自引:0,他引:2
53.
54.
Isoelectric focusing following by electrophoresis of proteins for visualizing their titration curves by zymogram and immunofixation 总被引:1,自引:0,他引:1
After isoelectric focusing followed by electrophoresis at right angles in the same gel slab, it is possible to visualize the titration curve of proteins by zymograms or immunofixation even of an unpurified sample. This information can be very useful for the selection of the proper purification strategy by charge-dependent methods, e.g. ion-exchange chromatography, zone and disc electrophoresis and isotachophoresis. The titration curve also gives information on the stability of the protein as a function of the prevailing pH of the medium, in the pH 3-10 range. A region of instability is found for most proteins in acidic conditions, below pH 4.5, while most proteins are stable in the alkaline pH region, at least up to pH 10. The best method for developing zymograms and immunoprints appears to pH 10. The best method for developing zymograms and immunoprints appears to be the 'sandwich technique', by which a thin agarose slab, cast on an hydrophilic polyester sheet, and impregnated with appropriate reagents, is left in contact with a polyacrylamide gel thin layer used to generate the titration curves. 相似文献
55.
56.
A note on estimation for gamma and stable processes 总被引:1,自引:0,他引:1
57.
Osamu Gotoh Jun-Ichi Hayashi Hiromichi Yonekawa Yusaku Tagashira 《Journal of molecular evolution》1979,14(4):301-310
Summary We have developed a theory to estimate the degree of sequence divergence between related DNAs from the comparison of restriction endonuclease recognition sites. Two major improvements have been made upon a similar method reported by Upholt (1977). First, the most probable value is calculated by the collective use of all available data. This reduces intrinsic statistical error and extends the analyzable range of sequence divergence. Second, all variables are redefined so that they have strict mathematical implications. This corrects a serious error arising from the misinterpretation of the meaning of the fraction of conserved cleavage sites. With this refined method, sequence divergence between rat and mouse mitochondrial DNAs (mtDNAs) was calculated to be about 25% substitutions/nucleotide, which is in good agreement with the DNA-DNA hybridization data obtained by Jakovcic et al. (1975). It was also estimated that the three types of rat mtDNAs differ from one another by 0.3 ~1% of total base pairs. These values are 2 ~5 times smaller than those obtained with the conventional method. 相似文献
58.
Maternal and neonatal disposition of pethidine in childbirth--a study using quantitative gas chromatography-mass spectrometry 总被引:1,自引:0,他引:1
J Caldwell L A Wakile L J Notarianni R L Smith G J Correy B A Lieberman R W Beard M D Finnie W Snedden 《Life sciences》1978,22(7):589-596
An assay for pethidine using gas chromatography-mass spectrometry with single ion monitoring has been developed for its analysis in the blood of neonates whose mothers received pethidine during childbirth. Concentrations were determined from the height of the peak at m/e 218 derived from pethidine compared with that at m/e 234 derived from the internal standard lignocaine. Results from 10 mothers and their babies show the time-related passage of pethidine across the placenta. The elimination half-life of the drug from neonatal blood was 22.7h compared with 3h in the adult. 相似文献
59.
Toshiaki Shinohara Michael W. Thomas Ellen G. Gilliam Virginia P. Wray Earl F. Walborg 《Archives of biochemistry and biophysics》1982,219(2):411-421
Novikoff hepatocellular carcinoma cells possess cell-surface glycoproteins that bind the lectin, concanavalin A. A subset of Con A-binding plasma membrane glycoproteins was solubilized by addition of n-butanol to a suspension of Novikoff cells. Glycoproteins solubilized into the n-butanol-saturated aqueous phase of the two-phase mixture were purified by sequential chromatography on DEAE-cellulose and Sepharose-conjugated concanavalin A. Glycoproteins specifically bound to the Sepharose-conjugated Con A exhibited apparent Mr = 72,000 to 125,000. The plasma membrane localization of these components was inferred by their isolation from cells surface labeled with NaIO4/ NaB3H4. A xenoantiserum, raised against glycoproteins specifically bound to Sepharose-conjugated concanavalin A was employed to identify reactive components in nonionic detergent extracts of Novikoff tumor cells or rat hepatocytes surface labeled using lactoperoxidase-catalyzed iodination (125I). Major reactive peptides in extracts of Novikoff cells exhibited apparent Mr = 74,000, 82, 000, 110,000, and 135,000, while those in extracts of hepatocytes possessed apparent Mr = 98,000 and 105,000. The reactivity of the antiserum with extracts of 125I-labeled Novikoff cells was abolished by absorption of the antiserum with hepatocytes, indicating that the qualitative differences observed may result from structural modification of one or more cell-surface glycoproteins, rather than the expression of new or inappropriate glycoproteins. This antiserum will provide a useful probe to investigate alterations in the expression or structure of glycoproteins that occur as a consequence of malignant transformation or adaptation of malignant cells to growth in the ascitic form. 相似文献
60.
Radial estimates and the test for sphericity 总被引:1,自引:0,他引:1