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   631篇
  免费   37篇
  2023年   6篇
  2022年   8篇
  2021年   10篇
  2020年   12篇
  2019年   12篇
  2018年   18篇
  2017年   16篇
  2016年   26篇
  2015年   16篇
  2014年   29篇
  2013年   36篇
  2012年   35篇
  2011年   38篇
  2010年   22篇
  2009年   20篇
  2008年   27篇
  2007年   40篇
  2006年   32篇
  2005年   40篇
  2004年   24篇
  2003年   26篇
  2002年   20篇
  2001年   12篇
  2000年   23篇
  1999年   10篇
  1998年   10篇
  1997年   3篇
  1996年   3篇
  1995年   8篇
  1993年   4篇
  1992年   5篇
  1991年   9篇
  1990年   10篇
  1989年   7篇
  1988年   4篇
  1987年   5篇
  1986年   2篇
  1985年   4篇
  1984年   4篇
  1983年   5篇
  1982年   4篇
  1981年   3篇
  1980年   2篇
  1978年   5篇
  1975年   1篇
  1974年   2篇
  1973年   3篇
  1972年   1篇
  1971年   1篇
  1967年   1篇
排序方式: 共有668条查询结果,搜索用时 15 毫秒
11.
The development of stem cell technology in combination with advances in biomaterials has opened new ways of producing engineered tissue substitutes. In this study, we investigated whether the therapeutic potential of an acellular porous scaffold made of type I collagen can be improved by the addition of a powerful trophic agent in the form of mesenchymal stromal cells conditioned medium (MSC‐CM) in order to be used as an acellular scaffold for skin wound healing treatment. Our experiments showed that MSC‐CM sustained the adherence of keratinocytes and fibroblasts as well as the proliferation of keratinocytes. Moreover, MSC‐CM had chemoattractant properties for keratinocytes and endothelial cells, attributable to the content of trophic and pro‐angiogenic factors. Also, for the dermal fibroblasts cultured on collagen scaffold in the presence of MSC‐CM versus serum control, the ratio between collagen III and I mRNAs increased by 2‐fold. Furthermore, the gene expression for α‐smooth muscle actin, tissue inhibitor of metalloproteinase‐1 and 2 and matrix metalloproteinase‐14 was significantly increased by approximately 2‐fold. In conclusion, factors existing in MSC‐CM improve the colonization of collagen 3D scaffolds, by sustaining the adherence and proliferation of keratinocytes and by inducing a pro‐healing phenotype in fibroblasts.  相似文献   
12.
The reversible phosphorylation of proteins mediates cellular signals in eukaryotic cells. RNA interference inhibits the expression of genes and proteins in a sequence-specific manner and provides a tool to study the functions of target molecules. The effect of RNA interference on protein phosphatase isoforms in HEK-293 cells was examined. Protein phosphatase 1 delta (PP1δ) sequence-specific double-stranded RNA (dsRNA) inhibited mRNA and protein expression of the PP18. This RNA interference did not affect the expression of α and γ1 isoforms of PP1. Transfection of antisense RNA specific for PP1δ also suppressed the expression of PP1δ. It was further demonstrated by an in vitro RNA cleavage assay that extracts of HEK-293 cells catalyzed the processing of dsRNA. This cell line had much stronger mRNA expression of Dicer, an RNase III-like enzyme, than did human osteoblastic MG63 cells. The present results show that RNA interference is a useful tool to distinguish between PP1 isoforms.  相似文献   
13.
In this study, the findings of three water mite species of the family Hygrobatidae collected from different streams in Turkey were evaluated. Hygrobates (s. str.) anatolicus Esen & Pešić, sp. n. is described as new for science. Hygrobates (Rivobates) diversiporus Sokolow, 1927 and Atractides (s. str.) nikooae Pešić, 2004, which were illustrated and thoroughly discussed, are new records for the Turkish fauna.  相似文献   
14.
15.
Methionine can be reversibly oxidized to methionine sulfoxide (MetO) under physiological conditions. Organisms evolved two distinct methionine sulfoxide reductase families (MSRA & MSRB) to repair oxidized methionine residues. We found that 5 MSRB genes exist in the soybean genome, including GmMSRB1 and two segmentally duplicated gene pairs (GmMSRB2 and GmMSRB5, GmMSRB3 and GmMSRB4). GmMSRB2 and GmMSRB4 proteins showed MSRB activity toward protein-based MetO with either DTT or thioredoxin (TRX) as reductants, whereas GmMSRB1 was active only with DTT. GmMSRB2 had a typical MSRB mechanism with Cys121 and Cys 68 as catalytic and resolving residues, respectively. Surprisingly, this enzyme also possessed the MSRB activity toward free Met-R-O with kinetic parameters similar to those reported for fRMSR from Escherichia coli, an enzyme specific for free Met-R-O. Overexpression of GmMSRB2 or GmMSRB4 in the yeast cytosol supported the growth of the triple MSRA/MSRB/fRMSR (Δ3MSRs) mutant on MetO and protected cells against H2O2-induced stress. Taken together, our data reveal an unexpected diversity of MSRBs in plants and indicate that, in contrast to mammals that cannot reduce free Met-R-O and microorganisms that use fRMSR for this purpose, plants evolved MSRBs for the reduction of both free and protein-based MetO.  相似文献   
16.
17.
Isovaleric acidemia (IVA) is a rare autosomal recessive disorder caused by a deficiency of isovaleryl-CoA dehydrogenase encoded by IVD gene. In this case study we report the first Saudi IVA patients from a consanguineous family with a novel transversion (p.G362V) and briefly discuss likely phenotype–genotype correlation of the disease in the Saudi population. We explored the functional consequences of the mutation by using various bioinformatics prediction algorithms and discussed the likely mechanism of the disease caused by the mutation.  相似文献   
18.
4-Amino-N-(4-sulfamoylphenyl)benzamide was synthesized by reduction of 4-nitro-N-(4-sulfamoylphenyl)benzamide and used to synthesize novel acridine sulfonamide compounds, by a coupling reaction with cyclic-1,3-diketones and aromatic aldehydes. The new compounds were investigated as inhibitors of the metalloenzyme carbonic anhydrase (CA, EC 4.2.1.1), and more precisely the cytosolic isoforms hCA I, II and VII. hCA I was inhibited in the micromolar range by the new compounds (KIs of 0.16–9.64 μM) whereas hCA II and VII showed higher affinity for these compounds, with KIs in the range of 15–96 nM for hCA II, and of 4–498 nM for hCA VII. The structure–activity relationships for the inhibition of these isoforms with the acridine–sulfonamides reported here were also elucidated.  相似文献   
19.
A series of hydroxy and phenolic compounds have been assayed for the inhibition of two physiologically relevant carbonic anhydrase (CA, EC 4.2.1.1) isozymes, the cytosolic human isozymes I and II. The investigated molecules showed inhibition constants in the range of 1.07–4003 and 0.09–31.5?μM at the hCA I and hCA II enzymes, respectively. In order to investigate the binding mechanisms of these inhibitors, in silico studies were also applied. Molecular docking scores of the studied compounds are compared using three different scoring algorithms, namely Glide/SP, Glide/XP and Glide/IFD. In addition, different ADME (absorption, distribution, metabolism and excretion) analysis was performed. All the examined compounds were found within the acceptable range of pharmacokinetic profiles.  相似文献   
20.
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