首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   8323篇
  免费   903篇
  国内免费   2篇
  2023年   44篇
  2021年   199篇
  2020年   113篇
  2019年   136篇
  2018年   172篇
  2017年   166篇
  2016年   241篇
  2015年   381篇
  2014年   427篇
  2013年   481篇
  2012年   640篇
  2011年   652篇
  2010年   409篇
  2009年   334篇
  2008年   479篇
  2007年   472篇
  2006年   403篇
  2005年   402篇
  2004年   408篇
  2003年   350篇
  2002年   316篇
  2001年   134篇
  2000年   106篇
  1999年   121篇
  1998年   86篇
  1997年   74篇
  1996年   51篇
  1995年   56篇
  1994年   46篇
  1993年   34篇
  1992年   85篇
  1991年   89篇
  1990年   56篇
  1989年   64篇
  1988年   44篇
  1987年   46篇
  1986年   48篇
  1985年   57篇
  1984年   63篇
  1983年   49篇
  1982年   34篇
  1981年   31篇
  1980年   31篇
  1979年   34篇
  1978年   36篇
  1977年   38篇
  1976年   33篇
  1974年   31篇
  1972年   35篇
  1971年   28篇
排序方式: 共有9228条查询结果,搜索用时 643 毫秒
71.
Phenol oxidase activity of activated A1 and A2 (A3) electrophoretic components from 19 lozenge mutant and three lozenge double mutant strains was compared to that of wild type flies. Melanin production by the activated A components with tyrosine as substrate was compared to activity in the same acrylamide gels with dopa as substrate. Melanin production decreased, first in the A1 band and then in the A2 (A3) band, with increased morphological expression of the mutant genes. No melanin bands were obtained with either substrate in five of the more severely affected mutants. A possible correlation between phenol oxidase activity and quinone production necessary for normal development of eyes, female accessory sex organs, and claws is discussed.Supported by PHS grant AM-08331-05.  相似文献   
72.
73.
74.
A man presented with the sudden onset of pernicious anaemia at the age of 21. He had been treated for hypothyroidism since the age of 6. His father and only paternal aunt were also found to have pernicious anaemia. Gastric and thyroid antibody studies showed one or more antibodies to be present in all three subjects, as well as in the patient''s mother.  相似文献   
75.
It is possible to stabilize foot-and-mouth disease antiserum by either freeze-drying in bottles or air-drying on paper for periods of 7 months.  相似文献   
76.
Results of the use of ampicillin, penicillin G and symptomatic therapy in the treatment of acute otitis media in 142 children were compared. Antibiotic therapy conveyed significant benefit. No major differences were observed between penicillin and ampicillin, except in the age group under 3 years where ampicillin was associated with the best results. Ampicillin appears to be the drug of choice. Its superiority over symptomatic therapy was statistically significant. Long-term sequelae were not observed in any of the three treatment groups. The relative merits of erythromycin and ampicillin require further study.  相似文献   
77.
The cystine-containing peptides of horse growth hormone were isolated and their amino acid sequences determined. Four unique half-cystine residues occur in two peptides, one containing 11 and the other, at the C-terminus of the protein, 15 amino acids. These sequences are compared with published data on growth hormones from other species.  相似文献   
78.
79.
80.
Sites of synthesis of plasma proteins in the foetal rat   总被引:4,自引:4,他引:0       下载免费PDF全文
1. The foetal rat of 16 or more days incorporates 14C-labelled amino acids into all the demonstrable plasma protein fractions in vivo. 2. Slices of foetal rat liver incubated in vitro incorporate 14C-labelled amino acids into the main plasma protein fractions, including the foetal-specific `post-albumin'. 3. Slices of placenta are unable to incorporate 14C-labelled amino acids into plasma proteins in vitro. 4. Liver slices from maternal rats incubated in vitro incorporate 14C-labelled amino acids into plasma proteins. The presence of post-albumin cannot be demonstrated after incubation. 5. Liver slices from foetal rats, but not from adult rats, contain demonstrable amounts of haemoglobin into which 14C-labelled amino acids are incorporated.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号