全文获取类型
收费全文 | 987篇 |
免费 | 67篇 |
出版年
2021年 | 12篇 |
2017年 | 11篇 |
2016年 | 8篇 |
2015年 | 21篇 |
2014年 | 32篇 |
2013年 | 28篇 |
2012年 | 41篇 |
2011年 | 38篇 |
2010年 | 44篇 |
2009年 | 30篇 |
2008年 | 33篇 |
2007年 | 29篇 |
2006年 | 40篇 |
2005年 | 27篇 |
2004年 | 39篇 |
2003年 | 27篇 |
2002年 | 31篇 |
2001年 | 28篇 |
2000年 | 30篇 |
1999年 | 28篇 |
1998年 | 14篇 |
1997年 | 11篇 |
1996年 | 12篇 |
1995年 | 14篇 |
1994年 | 11篇 |
1993年 | 12篇 |
1992年 | 26篇 |
1991年 | 25篇 |
1990年 | 14篇 |
1989年 | 15篇 |
1988年 | 13篇 |
1987年 | 11篇 |
1986年 | 20篇 |
1985年 | 11篇 |
1984年 | 12篇 |
1982年 | 12篇 |
1981年 | 10篇 |
1980年 | 8篇 |
1979年 | 23篇 |
1978年 | 21篇 |
1977年 | 18篇 |
1975年 | 12篇 |
1974年 | 15篇 |
1973年 | 12篇 |
1972年 | 6篇 |
1971年 | 8篇 |
1970年 | 9篇 |
1969年 | 9篇 |
1968年 | 6篇 |
1967年 | 6篇 |
排序方式: 共有1054条查询结果,搜索用时 15 毫秒
1.
B M Austen C J Evans D G Smyth 《Biochemical and biophysical research communications》1979,91(4):1211-1217
Peptide fragments derived from the NH2-terminus of corticotropin were found to exhibit widely differing degrees of stability to degradation by aminopeptidase M. Corticotropin itself was 135 times more stable than its NH2-terminal pentapeptide, and similar differences in stability were observed with peptides derived from the B-chain of bovine insulin. Enkephalin linked covalently to the A-chain of bovine insulin was at least 100 times more stable than the pentapeptide. The results demonstrate that the molecular size of a peptide is one factor that determines its NH2-terminal stability. 相似文献
2.
3.
Aimée Watt Smyth 《BMJ (Clinical research ed.)》1907,2(2439):849-850
4.
5.
Michael J. Smyth 《BMJ (Clinical research ed.)》1938,1(4028):646-647
6.
Specific processing of the thyrotropin-releasing prohormone in rat brain and spinal cord 总被引:1,自引:0,他引:1
Thyrotropin-releasing hormone (TRH) and TRH extended peptides were extracted from rat hypothalamus and spinal cord and resolved by gel exclusion chromatography under dissociating conditions. Peptides related to TRH were detected by trypsin digestion and radioimmunoassay with an antibody to TRH or an antibody raised against the pentapeptide Glp-His-Pro-Gly-Lys. In addition to the tripeptide hormone a series of C-terminally extended forms of TRH was shown to occur in both tissues; no N-terminally extended peptides were detected. The structure of the TRH-related peptides was confirmed by chromatographic identification of the N-terminal pentapeptide sequence released by trypsin. The TRH extended peptides, which accounted for 15-20% of the total TRH, were present in three groups of different molecular size corresponding to predicted fragments of the TRH prohormone. One of the peptides in the spinal cord was identified by chromatographic comparison with a synthetic 16-residue peptide representing residues 154-169 of the prohormone. In the spinal cord the TRH extended peptides differed in their relative concentrations from the corresponding peptides in the hypothalamus, possibly reflecting differences in processing. The finding of extended forms of TRH in which the extension occurs only on the C-terminal side of the hormone sequence shows that the prohormone undergoes highly specific processing. 相似文献
7.
Acute intermittent porphyria caused by a C→T mutation that produces a stop codon in the porphobilinogen deaminase gene 总被引:5,自引:1,他引:4
G. A. Scobie D. H. Llewellyn A. J. Urquhart S. J. Smyth N. A. Kalsheker P. R. Harrison G. H. Elder 《Human genetics》1990,85(6):631-634
Summary A mutation of the porphobilinogen (PBG) deaminase gene that produces the cross-reacting immunological material (CRIM)-negative type of acute intermittent porphyria (AIP) has been identified in one of 43 unrelated patients with this form of the disorder. The mutation is a CT transition that abolishes a PstI recognition site in exon 9 of the gene and converts a codon for glutamine to a stop codon. 相似文献
8.
Douglas A. Smyth 《Journal of Plant Growth Regulation》1992,11(2):125-128
Methylxanthine treatment of rice seeds (Oryza sativa L. cv. Lemont) was used to determine the relative efficiencies of caffeine (1,3,7-trimethylxanthine), theobromine (3,7-dimethylxanthine), and theophylline (1,3-dimethylxanthine) as growth regulators in a plant not producing these compounds. Caffeine inhibited growth more effectively than the dimethylxanthines. Treatment with 2.5 mM caffeine inhibited shoot elongation by half after 6 days of growth, and inhibited root elongation by 90% compared to control plants germinated in water. Although caffeine treatment inhibited growth of roots more than shoots, caffeine accumulation was similar in both organs. Apparently, shoots have a more effective mechanism than roots for maintaining growth in the presence of caffeine. 相似文献
9.
J F Templeton V P Kumar D Bose D D Smyth R S Kim F S LaBella 《Canadian journal of physiology and pharmacology》1988,66(11):1420-1424
The synthesis of the glucoside, 3 beta-[(beta-D-glucopyranosyl)oxy]-14-hydroxy-14 beta-pregn-4-en-20-one, a 14 beta-hydroxyprogesterone glucoside (14 beta-OHP-glu), is described. This compound has an IC50 of 1 microM in a [3H]ouabain binding assay, and is about 10 times more potent than the aglycone. Like 14 beta-hydroxyprogesterone, the glucoside enhances contractility of isolated cardiac muscle. 14 beta-OHP-glu or ouabain, when infused at comparable doses into the renal artery of the anesthetized rat, markedly increases urine volume. Whereas ouabain significantly enhances urinary potassium excretion with little or no effect on sodium excretion, 14 beta-OHP-glu promotes a marked natriuresis with no significant effect on potassium excretion. 相似文献
10.
Lack of inhibition by atrial natriuretic factor on cyclic AMP levels in single nephron segments and the glomerulus 总被引:1,自引:0,他引:1
S Umemura D D Smyth W A Pettinger 《Biochemical and biophysical research communications》1985,127(3):943-949
Recently an inhibitory effect of atrial natriuretic factor (ANF) on the adenylate cyclase system has been reported in vascular tissue. In seeking similar affects in renal tissue, we studied the effect of ANF on cyclic AMP levels in single nephron segments and in glomeruli from the rat. Individual nephron segments or glomeruli were incubated in the presence of a phosphodiesterase inhibitor, with or without parathyroid hormone (PTH) or arginine vasopressin (AVP) and varying concentrations of ANF at 37 degrees C for 2 min. The capacity for alpha 2-adrenoceptor inhibition of adenylate cyclase was demonstrated in the proximal convoluted tubule, cortical collecting tubule and in glomeruli. Nevertheless, ANF could not inhibit cAMP formation in any of these nephron segments nor in the glomerulus. Thus, unlike the vasculature, ANF has no inhibitory effect on cAMP formation in these renal tissues. 相似文献