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   1593篇
  免费   71篇
  2021年   11篇
  2019年   12篇
  2018年   16篇
  2017年   9篇
  2016年   21篇
  2015年   33篇
  2014年   36篇
  2013年   102篇
  2012年   81篇
  2011年   82篇
  2010年   52篇
  2009年   42篇
  2008年   75篇
  2007年   66篇
  2006年   73篇
  2005年   77篇
  2004年   81篇
  2003年   79篇
  2002年   96篇
  2001年   39篇
  2000年   32篇
  1999年   37篇
  1998年   32篇
  1997年   16篇
  1996年   17篇
  1995年   14篇
  1994年   12篇
  1993年   9篇
  1992年   40篇
  1991年   18篇
  1990年   27篇
  1989年   26篇
  1988年   28篇
  1987年   26篇
  1986年   14篇
  1985年   21篇
  1984年   12篇
  1983年   12篇
  1982年   15篇
  1981年   17篇
  1980年   12篇
  1979年   17篇
  1977年   11篇
  1976年   12篇
  1974年   10篇
  1973年   12篇
  1972年   10篇
  1971年   9篇
  1970年   10篇
  1967年   11篇
排序方式: 共有1664条查询结果,搜索用时 31 毫秒
11.
We have studied ouabain-resistant, external sodium-stimulated, lithium efflux (LiNa countertransport) in red blood cells from 21 borderline hypertensives with at least one hypertensive first degree relative (BH-F), 19 borderline hypertensives without family history of essential hypertension (BH-NF), and 35 age-matched normotensive subjects. The data indicate the finding of an increased LiNa countertransport in all BH (F+NF), but with a significant overlap between BH values and control ones: LiNa countertransport is significantly higher only in BH-F but it is normal in BH-NF. Moreover, there is a significant correlation of LiNa countertransport to total peripheral resistance but not to mean blood pressure in all hypertensive patients. It is suggested that in BH the increase of erythrocyte Na flux is mediated by the NaNa exchange diffusion, and its abnormality may be associated to the hereditary trait of essential hypertension rather than the high blood pressure per se, probably resulting in the development of hypertension, through the increased vascular smooth muscle tone.  相似文献   
12.
13.
14.
15.
Human laminin a chain (LAMA) gene: Chromosomal mapping to locus 18p11.3   总被引:1,自引:0,他引:1  
Laminin, an integral component of basement membranes, consists of three subunit polypeptides, A, B1, and B2 chains. We have recently isolated cDNAs corresponding to human laminin A chain. These cDNAs were utilized for chromosomal in situ hybridizations to establish the genomic location of the laminin A chain gene. Metaphase chromosomes of PHA-stimulated human peripheral blood leukocytes were examined by in situ hybridization with 3H-labeled cDNAs, and the chromosomes were identified by R-banding (fluorochrome-photolysis-Giemsa method). The results indicated that the human laminin A chain is at locus 18p11.3. Since human laminin B1 and B2 chain genes have been previously mapped to chromosomes 7 and 1, respectively, the results indicate that genes encoding human laminin chains reside in separate chromosomes.  相似文献   
16.
Identification of alpha 2-macroglobulin as a carrier protein for IL-6   总被引:8,自引:0,他引:8  
In this report we demonstrate that alpha 2-macroglobulin (alpha 2M) is a carrier protein for IL-6. IL-6 was found to bind plasma proteins and an immunoblot analysis revealed that the complex between IL-6 and plasma proteins contains alpha 2M. Furthermore, purified alpha 2M bound IL-6. alpha 2M did not inhibit IL-6 activity or its binding to homologous receptor. IL-6 bound to alpha 2M retained its biologic activity and became resistant to treatment with proteases, although free IL-6 was easily degraded. These findings indicate that alpha 2M plays an important role as a carrier protein for IL-6 in serum and makes IL-6 produced at the local inflammatory site available to lymphocytes, hepatocytes, and hematopoietic stem cells, resulting in the induction of the coordinate systemic host defense reactions, such as immune response, acute phase reaction, and hematopoiesis.  相似文献   
17.
18.
We have identified the cDNAs encoding pheromone biosynthesis activating neuropeptide (PBAN) using PCR technique. The nucleotide sequence showed that the PBAN gene encodes, besides PBAN, diapause hormone and three putative amidated peptides. These four peptides share with PBAN the C-terminal pentapeptide amide which is corresponding to the shortest fragment with pheromonotropic activity. The organization of the PBAN gene is characteristic of several short neuropeptides and has some degree of similarity to that of the gene for the insect neuropeptide FMRFamide. Thus, the PBAN gene products construct a family of structurally related peptides and have various biological functions.  相似文献   
19.
To clarify the roles of metalloproteinases and their inhibitor (TIMP) in diabetic glomerulopathy, we studied the effect of a high glucose concentration on the gene expression of metalloproteinase transin and TIMP as well as collagen type IV and laminin in cultured rat mesangial cells (MCs). In the high glucose group, collagen type IV, laminin, and TIMP mRNA levels were all elevated in a concentration-dependent manner, whereas transin expression was suppressed. Osmotic control of high glucose with mannitol selectively stimulated TIMP expression. We hypothesize that high glucose decreases matrix-degrading activity as well as increases matrix productivity in MCs.  相似文献   
20.
Summary To breed industrially useful strains of a slow-growing, red-pigment-producing strain ofMonascus anka, protoplasts ofM. anka MAK1 (arg) andAspergillus oryzae AOK1 (met, thr) were fused. A mixture of protoplasts prepared from mycelia ofM. anka MAK1 treated with 2% Usukizyme and ofA. oryzae AOK1 treated with 2% Usukizyme and 0.2% NovoZym 234 was incubated with 30% (w/v) polyethylene glycol no. 6000. Heterokaryon fusants complementing the auxotrophies of both mutants were isolated on minimal medium, but segregated into red (MAK1) and white (AOK1) sectors after being cultured on a complete medium. After irradiation with UV light, the fusants gave stable heterozygous diploids that formed long white hyphae. These diploids, which had twice as much DNA in the nucleus as their parents, grew more rapidly than the parent strain YZT1, and produced ethanol earlier than the parents. Production of amylase, protease, and kojic acid by the fusants was intermediate in amount between that of the two parents.  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