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   319篇
  免费   11篇
  2022年   5篇
  2021年   8篇
  2020年   5篇
  2019年   4篇
  2018年   9篇
  2017年   9篇
  2016年   8篇
  2015年   14篇
  2014年   13篇
  2013年   21篇
  2012年   25篇
  2011年   26篇
  2010年   11篇
  2009年   14篇
  2008年   25篇
  2007年   24篇
  2006年   16篇
  2005年   14篇
  2004年   10篇
  2003年   14篇
  2002年   13篇
  2001年   4篇
  2000年   4篇
  1999年   1篇
  1998年   5篇
  1997年   1篇
  1996年   4篇
  1995年   2篇
  1994年   2篇
  1993年   2篇
  1992年   3篇
  1991年   1篇
  1990年   1篇
  1988年   1篇
  1987年   1篇
  1986年   1篇
  1983年   1篇
  1982年   5篇
  1981年   1篇
  1980年   1篇
  1979年   1篇
排序方式: 共有330条查询结果,搜索用时 15 毫秒
121.
122.
A series of 31 resveratrol derivatives was designed, synthesized and evaluated for activation and inhibition of the TRPA1 channel. Most acted as activators and desensitizers of TRPA1 channels like resveratrol or allyl isothiocyanate (AITC). Compound 4z (HUHS029) exhibited higher inhibitory activity than resveratrol with an IC50 value of 16.1 μM. The activity of 4z on TRPA1 was confirmed in TRPA1-expressing HEK293 cells, as well as in rat dorsal root ganglia neurons by a whole cell patch clamp recording. Furthermore, pretreatment with 4z exhibited an analgesic effect on AITC-evoked TRPA1-related pain behavior in vivo.  相似文献   
123.
124.
Rosmarinic acid is the dominant hydroxycinnamic acid ester accumulated in Boraginaceae and Lamiaceae plants. A cytochrome P450 cDNA was isolated by differential display from cultured cells of Lithospermum erythrorhizon, and the gene product was designated CYP98A6 based on the deduced amino acid sequence. After expression in yeast, the P450 was shown to catalyze the 3-hydroxylation of 4-coumaroyl-4'-hydroxyphenyllactic acid, one of the final two steps leading to rosmarinic acid. The expression level of CYP98A6 is dramatically increased by addition of yeast extract or methyl jasmonate to L. erythrorhizon cells, and its expression pattern reflected the elicitor-induced change in rosmarinic acid production, indicating that CYP98A6 plays an important role in regulation of rosmarinic acid biosynthesis.  相似文献   
125.
Abstract Primers to amplify the genes encoding the virulence factors of uropathogenic Escherichia coli , such as pilus associated with pyelonephritis ( pap ), haemolysin ( hly ), aerobactin ( aer ) and cytotoxic necrotizing factor 1 ( cnf 1) genes, were designed. The above primers along with previously reported primers for S fimbriae ( sfa ) and afimbrial adhesin I ( afaI ) genes were combined to develop a multiplex polymerase chain reaction (PCR) for detection of the respective virulence factors and for the identification of uropathogenic E. coli . The multiplex PCR to detect pap, sfa, afa I, hly, aer and cnf 1 genes was highly specific and the sensitivity was found to be about 5 × 103 colony forming units of E. coli per ml. A total of 194 E. coli strains isolated from patients with simple acute cystitis were examined by the multiplex PCR and the results were in complete agreement with that obtained by DNA colony hybridization test. The multiplex PCR developed was, therefore, concluded to be a useful, sensitive and rapid assay system to identify uropathogenic E. coli .  相似文献   
126.
The plant growth-promoting activities of brassinolide and brassinosteroids with different side chains were investigated by means of the Raphanus an  相似文献   
127.
The present clinical trials revealed that 16,16-Dimethyl-trans-δ2-PGE1 methyl ester in the form of vaginal suppositories is highly effective in inducing mid-trimester termination of pregnancies. It also showed that prior treatment with laminaria and metreurynter may enhance the success rate while reducing the incidence and severity of side effects. It is easy and safe to use clinically, with minimal side effects, and in our series, revealed no deleterious effects on ensuing reproductive physiology. However, the definite mechanism involved in the action of this new analogue to cause myometrial contractions is still not completely understood, and requires further intensive investigation.  相似文献   
128.
Summary Some effects of culturing adult rat hepatocytes on each of four different substrates—laminin (LN), collagen type I (C-I), collagen type IV (C-IV), and fibronectin (FN)—have been investigated under defined conditions. No differential effect on the attachment of the cells to the various substrates was noted; however, the spreading of hepatocytes shortly after initial plating was most strikingly enhanced by FN, whereas LN exhibited little or no such enhancement. The two collagen substrates enhanced the spreading of hepatocytes more than did LN, but less than FN. The different substrates had no differential effect on the induction of tyrosine aminotransferase by dexamethasone and glucagon for at least the first 10 d in culture. The longevity of the hepatocytes was not changed significantly by any of the substrates, at least through the 14th d of culture. During the culture periods the hepatocytes at high cell density were maintained as confluent monolayers, regardless of the substrate on which they had been cultured. After 14 d of culture, γ-glutamyltranspeptidase activity was highest in cells cultured on C-IV, and lowest in those on FN. DNA synthesis in cultured hepatocytes at a low cell density was highest in cells cultured on FN, with decreasing levels of this parameter in cells cultured on C-IV, C-I, and LN, respectively. These results demonstrate that specific components of the extracellular matrix modulate both differentiated functions and the replication of hepatocytes cultured in serum-free medium. This work was supported in part by grants (CA-07175, CA-09135, CA-22484) from the National Cancer Institute, Bethesda MD. N. Sawada was supported by a Cancer Research Campaign Grant D (U.K.) from the International Union Against Cancer.  相似文献   
129.
Tetrakis{(alpha,alpha,alpha,alpha-o-pivalamido)phenyl}porphinatoiron(II) with a bifunctional tail possessing an axially coordinated imidazolyl group and a protein attachable succinimidyl(glutamyl) group (FeP-GluSu) has been synthesized. It can efficiently react with the lysine residues of recombinant human serum albumin (rHSA), giving a new albumin-heme conjugate [rHSA(FeP-Glu)]. MALDI-TOFMS showed a distinct molecular ion peak at m/z 70 643, which indicates that three FeP-Glu molecules were covalently linked to the rHSA scaffold. The binding number of FeP-Glu is approximately three (mol/mol) and independent of the mixing ratio. The CD spectrum and Native PAGE revealed that the albumin structure remained unaltered after the covalent bonding of the hemes. This rHSA(FeP-Glu) conjugate can bind and release O2 reversibly under physiological conditions (pH 7.3, 37 degrees C) in the same manner as hemoglobin and myoglobin. The O2-adduct complex had a remarkably long lifetime (tau(1/2): 5 h). The O2-binding affinity [P(1/2)O2: 27 Torr] was identical to that of human red cells. Laser flash photolysis experiments gave the O2- and CO-association rate constants and suggested that there are two different geometries of the imidazole binding to the central ion.  相似文献   
130.
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