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   3064篇
  免费   186篇
  国内免费   2篇
  2021年   21篇
  2019年   21篇
  2018年   41篇
  2017年   30篇
  2016年   44篇
  2015年   62篇
  2014年   81篇
  2013年   173篇
  2012年   152篇
  2011年   158篇
  2010年   94篇
  2009年   75篇
  2008年   132篇
  2007年   159篇
  2006年   115篇
  2005年   131篇
  2004年   146篇
  2003年   128篇
  2002年   122篇
  2001年   102篇
  2000年   119篇
  1999年   106篇
  1998年   31篇
  1997年   35篇
  1996年   31篇
  1995年   29篇
  1994年   26篇
  1993年   26篇
  1992年   77篇
  1991年   63篇
  1990年   65篇
  1989年   60篇
  1988年   73篇
  1987年   50篇
  1986年   59篇
  1985年   49篇
  1984年   34篇
  1983年   44篇
  1982年   25篇
  1981年   18篇
  1980年   18篇
  1979年   27篇
  1978年   25篇
  1977年   17篇
  1976年   14篇
  1975年   13篇
  1974年   21篇
  1973年   13篇
  1971年   13篇
  1970年   14篇
排序方式: 共有3252条查询结果,搜索用时 703 毫秒
51.
Fibroblast growth factor in the human placenta   总被引:5,自引:0,他引:5  
Fibroblast growth factor (FGF) has been purified 333,000-fold from human placenta by a combination of salt precipitation, cation-exchange chromatography, and Heparin-Sepharose affinity chromatography. Molecular weight (15-16 kDaltons), amino acid composition, bioactivity and immunological crossreactivity with bovine pituitary FGF indicate that the mitogens from the two species are closely related molecules.  相似文献   
52.
Macromolecules purified from Lentinus edodes mycelia cultureenhanced adventitious root formation in Azukia epicotyl cuttings.Partial purification by sequential column chromatographies gavematerial composed of 71% polysaccharides and 29% proteins. Thesugar moiety consisted of mainly xylose, glucose and arabinose,the sum of their contents being more than 76% of the total carbohydrates.The protein moiety consisted of mainly glycine and serine, whichaccounted for more than 40% of the total amino acid residues. (Received June 9, 1984; Accepted November 12, 1984)  相似文献   
53.
DNA cleavage analyses with EcoRI, HindIII and BamHI were carried out to investigate genome types of recent Ad 4 isolates obtained from acute respiratory disease (8 strains), and ocular disease (11 strains) in Japan. DNA cleavage patterns of all 19 isolates studied were identical regardless of whether they were recovered from respiratory tract or conjunctiva, but were distinct from that of the prototype strain.  相似文献   
54.
For radioimmunoassay of the catechol estrogens, four hapten-bovine serum albumin (BSA) conjugates were prepared from 6-oxo-2-hydroxyestradiol 6-(O-carboxymethyl)oxime, 2-hydroxyestradiol 17-hemisuccinate, 6-oxo-4-hydroxyestradiol 6-(O-carboxymethyl)oxime and 4-hydroxyestradiol 17-hemisuccinate by coupling with BSA, employing the mixed anhydride method. The antisera elicited in rabbits by immunization with these antigens showed high affinity and specificity for 2-hydroxyestradiol or 4-hydroxyestradiol with cross-reactivities to a few structurally related estrogens. The specificity of antisera obtained is discussed in relation to the site of attachment of the hapten to BSA.  相似文献   
55.
Mechanisms controlling pigment movements in the melanophore of the blue damselfish, Chrysiptera cyanea, were studied. Histological observations revealed that the melanophore had three-dimensionally developed processes to envelop overlying small iridophores, and thus participated in the construction of a simple dermal chromatophore unit. Nervous stimulation, catecholamines and melatonin brought about melanosome aggregation in the melanophore. The actions of the nervous stimulation and catecholamines were antagonized by alpha adrenolytic agents. A beta adrenergic agonist, metaproterenol, adenosine and adenine nucleotides, and alpha-MSH acted as pigment-dispersing agents. These results indicate that the melanophore of the present material is controlled quite orthodoxly by adrenergic nerves and endocrines, notwithstanding the fact that it has quite a unique morphology among fish species, and that its motile rate is remarkably high.  相似文献   
56.
Adenovirus type 8 (Ad 8) has been the major and important causative agent of epidemic keratoconjunctivitis (EKC). By enzymatic cleavage analysis with five endonucleases, PstI, HindIII, BamHI, SalI and SstI, 27 out of 149 Ad 8 isolates recovered from patients with EKC during the period from July, 1980 to July, 1981 in Kaohsiung, Taiwan, were studied. By cleavage patterns, 27 Ad 8 isolates in Kaohsiung were classified into four subtypes which were found to be different from the subtypes (Ad 8A, Ad 8B) prevalent in Sapporo (1).  相似文献   
57.
58.
Large amounts of cysteine proteinase inhibitors were found in bovine colostrum. One had a molecular weight of 90,000, and the other a molecular weight of 10,500. The concentrations of both these inhibitors were highest the day after parturition, and were about one-tenth as much on day 7. The lower molecular weight inhibitor was purified by acid treatment, ammonium sulfate fractionation, gel filtration on Sephadex G-50, CM-Sephadex chromatography and rechromatography on Sephadex G-50. The purified preparation gave a single band on SDS-polyacrylamide gel electrophoresis. This inhibitor contained one tryptophanyl residue and one cystinyl residue, and did not contain a free thiol group. Values obtained for its isoelectric point (pI) were 10.0 and 10.3. This material strongly inhibited cathepsin B, cathepsin H, and papain. the higher molecular weight inhibitor was partially purified. It had a pI of 4.2 and inhibited papain, cathepsin H, and cathepsin B.  相似文献   
59.
A mouse hybridoma cell line producing monoclonal antibody, F10, was established from mice hyperimmunized with cells bearing adult T cell leukemia (ATL) virus (ATLV). F10 antibody reacted with an ATLV structural polypeptide ( gp21 ) with a m.w. of 21,000 that was glycosylated on cell surfaces. The gp21 was expressed on cell surfaces of all ATL-associated antigen (ATLA)-positive human cell lines but not on ATLA-negative cell lines nor peripheral blood leukocytes stimulated with mitogens. The gp21 was also detected with anti-ATLA-positive human serum, and the binding of F10 antibody to ATLA-positive cell surfaces was significantly blocked by pretreatment with anti-ATLA-positive human sera. Double immunofluorescence staining with F10 antibody and anti-ATLA-positive human serum caused co-capping on cell surfaces, which suggests that gp21 co-exists with other ATLV antigens expressed on cell surfaces. Immunoprecipitation studies also suggested that the gp21 is a minor component of the ATLV envelope.  相似文献   
60.
Changes in the activity of serum gamma-glutamyl transpeptidase (gamma-GTP) and the percentage of the gamma-GTP fraction in healthy young men given a high carbohydrate diet (480-636 g/day, 80% of the total energy) for 21 days were examined. Serum total gamma-GTP activity showed no significant change in four healthy young volunteers who received high carbohydrate diet for 21 days. However, the percentage of the gamma-GTP (1) fraction increased significantly (P less than 0.01) from the basal level of 55.6 +/- 4.0% to 67.6 +/- 0.9% on day 10, and then decreased to 58.4 +/- 1.4% on day 21. When the experimental diet was replaced by usual diet, the percentage of the gamma-GTP (1) fraction returned to the same level as before the experiment. It is concluded from the results that the nutrient intake affects the percentage of gamma-GTP (1), but not the total serum gamma-GTP activity.  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