全文获取类型
收费全文 | 317篇 |
免费 | 32篇 |
专业分类
349篇 |
出版年
2023年 | 6篇 |
2021年 | 6篇 |
2020年 | 4篇 |
2019年 | 4篇 |
2018年 | 6篇 |
2016年 | 7篇 |
2015年 | 12篇 |
2014年 | 12篇 |
2013年 | 15篇 |
2012年 | 21篇 |
2011年 | 9篇 |
2010年 | 7篇 |
2009年 | 5篇 |
2008年 | 7篇 |
2007年 | 13篇 |
2006年 | 8篇 |
2005年 | 16篇 |
2004年 | 13篇 |
2003年 | 8篇 |
2002年 | 17篇 |
2001年 | 15篇 |
2000年 | 16篇 |
1999年 | 6篇 |
1998年 | 7篇 |
1997年 | 5篇 |
1996年 | 3篇 |
1995年 | 3篇 |
1994年 | 3篇 |
1993年 | 4篇 |
1992年 | 4篇 |
1991年 | 3篇 |
1990年 | 4篇 |
1989年 | 3篇 |
1988年 | 8篇 |
1987年 | 7篇 |
1986年 | 4篇 |
1985年 | 12篇 |
1984年 | 3篇 |
1983年 | 7篇 |
1982年 | 3篇 |
1980年 | 2篇 |
1975年 | 2篇 |
1973年 | 2篇 |
1972年 | 2篇 |
1969年 | 2篇 |
1968年 | 2篇 |
1967年 | 2篇 |
1966年 | 4篇 |
1965年 | 2篇 |
1964年 | 2篇 |
排序方式: 共有349条查询结果,搜索用时 0 毫秒
341.
342.
Two new fluorescent crosslinking amino acids named oxodesmosine and isooxodesmosine were isolated from bovine aorta elastin. These amino acids have unique structure, both N-substituted dihydrooxopyridine skeletons. 相似文献
343.
Two leucyl-tRNA synthetases (EC 6.1.1.4) have been purified to near homogeneity, the one from mitochondria and the other from cytoplasm of Tetrahymena pyriformis. Both enzymes were found to be structurally unrelated, single polypeptides with molecular weights of approximately 100,000 as determined by gel permeation, sucrose gradient centrifugation, and sodium dodecyl sulfate-polyacrylamide-gel electrophoresis. These enzymes behaved differently in elution profiles through hydroxyapatite- and diethylaminoethyl cellulose-column chromatography and isoelectric focusing. The two enzymes also showed some differences in responses to various salts for charging and in pH optima and temperature sensitivity, but no significant difference was found in their affinities (Km) for ATP and leucine. These enzymes recognized different leucyl-tRNA isoaccepting species as revealed by reversed-phase column chromatography. The mitochondrial enzyme can charge six isoaccepting leucyl-tRNA species, while the cytoplasmic enzyme can recognize only four species. 相似文献
344.
Serum thrombocytopoietic activity was measured by radioisotope bioassay in several groups of patients with disturbed thrombocytopoiesis. More or less serum activity was demonstrated in nearly all groups of patients with thrombocytopenia or elevated platelet count. The test system used proved to be more sensitive than counting circulating platelets. 相似文献
345.
346.
A peptide derived from rat urinary prokallikrein by trypsin treatment comprised 7 amino acids, the sequence (Ala-Pro-Pro-Val-Gln-Ser-Arg) of which was identical with that of the N-terminal region in prokallikrein. Thus, with trypsin treatment, rat urinary prokallikrein is converted to the active form with the release of the N-terminal propeptide consisting of 7 amino acids. An Arg-1-Val+1 bond in the prokallikrein was found to be the site of proteolytic cleavage of the propeptide. 相似文献
347.
M Ogata M Iwasaki S Kubo I Nakasono H Suyama K Kinoshita S Ikeda S Momida M Ichimaru 《Human heredity》1990,40(5):253-256
The serum Gc, Hp and alpha 2HS phenotypes were examined in 64 subjects known to have the human T-lymphotropic leukemia virus type I (HTLV-I) infection and in 60 uninfected subjects. There were no significant differences in the distributions of Gc, Hp and alpha 2HS phenotype and allele frequencies between any grouping of HTLV-I-infected subjects and the controls. No association between the Gc, Hp and alpha 2HS genotypes and susceptibility to adult T-cell leukemia was found. 相似文献
348.
We report a more efficient and well-defined algorithm for predicting a secondary structure of single-stranded nucleic acid from a primary nucleotide sequence. Using this algorithm, one- and two-dimensional bonding-probability maps of 5S rRNA of thermus thermophilus HB8 were calculated. These maps well express the stability of the secondary structure. 相似文献
349.
Summary We present a phenomenological theory expressing the constraints operating on the (G+C) contents of the three codon positions, i.e., first, second, and third bases of codons, by using the smallest number of constraint parameters having clear physical and genetic meaning. Theoretical curves displaying base composition at each of the three codon sites are given. The agreement between the theoretical curves and the data points of 1277 genes is quite good irrespective of the species from which the DNAs originated; the curves might be universal ones and the constraint parameters might have general biological meanings in relation to the DNA/RNA and protein functions. 相似文献