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   993篇
  免费   33篇
  国内免费   1篇
  1027篇
  2023年   15篇
  2022年   10篇
  2021年   24篇
  2020年   11篇
  2019年   10篇
  2018年   22篇
  2017年   25篇
  2016年   40篇
  2015年   36篇
  2014年   59篇
  2013年   67篇
  2012年   85篇
  2011年   81篇
  2010年   60篇
  2009年   49篇
  2008年   69篇
  2007年   46篇
  2006年   58篇
  2005年   58篇
  2004年   58篇
  2003年   64篇
  2002年   40篇
  2001年   6篇
  2000年   6篇
  1999年   2篇
  1998年   6篇
  1997年   3篇
  1996年   3篇
  1994年   5篇
  1993年   1篇
  1992年   2篇
  1991年   2篇
  1989年   1篇
  1984年   1篇
  1979年   1篇
  1977年   1篇
排序方式: 共有1027条查询结果,搜索用时 15 毫秒
101.
102.
Cisplatin, one of the most active cytotoxic agents against cancer, has several toxicities. Hepatotoxicity is one of them occurred during high doses treatment. The aim of this study was to determine the effects of erdosteine against cisplatin-induced liver injury through tissue oxidant/antioxidant parameters and light microscopic evaluation. The rats were randomly divided into three groups: control (n=5), cisplatin (10 mg/kg, n=6) and cisplatin+erdosteine (50 mg/kg/day oral erdosteine, n=8) groups. The rats were sacrificed at the 5th day of cisplatin treatment. The liver tissues were examined with light microscopy and oxidant/antioxidant biochemical parameters. The malondialdehyde (MDA) and nitric oxide (NO) levels were increased in the cisplatin group in comparison with the control and cisplatin+erdosteine groups (p<0.05). There was no significant difference in MDA and NO levels between control and cisplatin+erdosteine groups. The activities of superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GSH-Px) were higher in cisplatin+erdosteine group than cisplatin group (p<0.05). However, the CAT and GSH-Px activities were significantly lower in cisplatin group than in control group (p<0.05). The light microscopic examination revealed that cytoplasmic changes especially around cells of central vein were observed in cisplatin group. Hepatocellular vacuolization was seen in these cells. In the cisplatin plus erdosteine group, a decrease in cytoplasmic changes with the hepatocytes and sinusoidal dilatations around cells of central vein were noticed in as compared to cisplatin group. In the light of microscopic and biochemical results, it was concluded that cisplatin-induced liver damage in high dose and erdosteine prevented this toxic side effect by the way of its antioxidant and radical scavenging effects. (Mol Cell Biochem 278: 79–84, 2005)  相似文献   
103.
104.
ArrayExpress is a public microarray repository founded on the Minimum Information About a Microarray Experiment (MIAME) principles that stores MIAME-compliant gene expression data. Plant-based data sets represent approximately one-quarter of the experiments in ArrayExpress. The majority are based on Arabidopsis (Arabidopsis thaliana); however, there are other data sets based on Triticum aestivum, Hordeum vulgare, and Populus subsp. AtMIAMExpress is an open-source Web-based software application for the submission of Arabidopsis-based microarray data to ArrayExpress. AtMIAMExpress exports data in MAGE-ML format for upload to any MAGE-ML-compliant application, such as J-Express and ArrayExpress. It was designed as a tool for users with minimal bioinformatics expertise, has comprehensive help and user support, and represents a simple solution to meeting the MIAME guidelines for the Arabidopsis community. Plant data are queryable both in ArrayExpress and in the Data Warehouse databases, which support queries based on gene-centric and sample-centric annotation. The AtMIAMExpress submission tool is available at http://www.ebi.ac.uk/at-miamexpress/. The software is open source and is available from http://sourceforge.net/projects/miamexpress/. For information, contact miamexpress@ebi.ac.uk.  相似文献   
105.
106.
Identification and sequence analysis of chicken Toll-like receptors   总被引:11,自引:2,他引:9  
Toll-like receptors (TLRs) play an important role in the recognition of microbial components. Only chicken TLR2 and -4 have been reported in the literature. The objectives of this study were to identify new chicken TLRs and to evaluate evolutionary significance of these receptors. Searching chicken genomic databases and DNA sequencing revealed five new TLRs, TLR1 (type 1 and 2), -3, -5, and -7. No chicken orthologues of mammalian TLR8, -9, or -10 were found. As in mammals, all chicken TLRs (chTLRs) share identical protein secondary structure that consists of several leucine-rich domains, a transmembrane domain, and Toll/Interleukin-1 receptor domain(s). Phylogenetic analyses indicate that the identified chTLR genes are the orthologues of TLRs in mammals. Analyses of the number of synonymous substitutions per synonymous site and nonsynonymous substitutions per nonsynonymous site indicate that the nucleotide sequences coding for the leucine-rich repeats of chicken TLR1 type 1 and type 2 were significantly under positive Darwinian selection. In contrast, the sequences of other TLRs were under purifying selection. These results support the hypothesis that one of the major evolutionary strategies of the innate immune system is to recognize a few highly conserved microbial components with several conserved TLRs. The results also indicate that the sequence changes in the ligand-binding domains of TLR1 in chickens provide adaptive advantages during evolution.Nucleotide sequence data reported are available in GenBank database under the accession numbers AY633573–AY633577  相似文献   
107.
The leafy parts of thyme and its essential oil have been used in foods for its flavour, aroma and preservation for many years. In the present study the genotoxic potential of major compounds of thyme oil, i.e. thymol, carvacrol, and gamma-terpinene and of the methanolic extracts of thyme, were investigated in human lymphocytes by single-cell gel electrophoresis. Also, the effects of these substances on the induction of DNA damage by 2-amino-3-methylimidazo[4,5-f]-quinoline (IQ) and mitomycin C (MMC) were evaluated. No increase in DNA strand breakage was observed at thymol and gamma-terpinene concentrations below 0.1 mM, but at the higher concentration of 0.2 mM significant increases in DNA damage were seen. Thymol and gamma-terpinene significantly reduced the DNA strand breakage induced by IQ and MMC at the lower concentrations studied. Carvacrol, which is an isomer of thymol, seemed to protect lymphocytes from the genotoxic effects of IQ and MMC at non-toxic concentrations below 0.05 mM, but at the higher concentration of 0.1 mM carvacrol itself induced DNA damage. Also the constituents of the n-hexane and ethyl acetate fractions prepared from the concentrated aqueous methanolic extracts of Thymus spicata protected lymphocytes against IQ- and MMC-induced DNA damage in a concentration-dependent manner.  相似文献   
108.
Sternbergia fischeriana is an endangered geophyte and therefore in vitro micropropagation of this plant will have great importance for germplasm conservation and commercial production. Bulb scale and immature embryo explants of S. fischeriana were cultured on different nutrient media supplemented with various concentrations of plant growth regulators. Immature embryos produced higher number of bulblets than bulb scales. Large numbers of bulblets were regenerated (over 80 bulblets/explants) from immature embryos on Murashige and Skoog (MS) medium supplemented with 4 mg l–1 6-benzylaminopurine (BA) and 0.25 mg l–1 -naphthaleneacetic (NAA) or 2 mg l–12,4-dichlorophenoxyacetic acid (2,4-D) after 14 months of culture initiation. Regenerated bulblets were kept at 5 °C for 5 weeks and then transplanted to a potting mixture.  相似文献   
109.
Biochemical specialization within Arabidopsis RNA silencing pathways   总被引:1,自引:0,他引:1  
Qi Y  Denli AM  Hannon GJ 《Molecular cell》2005,19(3):421-428
In plants, the RNA silencing machinery responds to numerous inputs, including viral infection, microRNAs, and endogenous siRNAs that may act both in trans and in cis. Additionally, the full spectrum of silencing outcomes has been demonstrated in plants, ranging from mRNA degradation to repression at the level of protein synthesis to chromatin remodeling. Genetic studies in Arabidopsis have indicated that individual response pathways are functionally compartmentalized. However, to date, no biochemical systems have been available to investigate the roles of specific proteins within silencing pathways or the effects of selected mutations on the biochemical activity of those components. Here, we describe the generation of Arabidopsis extracts that reproduce many aspects of RNA silencing reactions in vitro. We find that specific members of the Dicer and Argonaute families have distinct biochemical activities, which provides insight into their roles within RNA silencing pathways in Arabidopsis.  相似文献   
110.
Echinococcosis, also known as hydatid disease or hydatidosis, is a zoonotic illness caused by the larval form of Echinococcus spp. It is highly prevalent in areas where the parasite is endemic such as the Mediterranean region. However, occurrence of echinococcosis and cancer together is rare. We treated and followed approximately 1200 patients with different hematologic neoplastic diseases between 1985 and 2003, and only one of these individuals had concomitant acute leukemia and liver hydatidosis. This report describes the case of a 19-year-old man who had both primary refractoriness of acute leukemia (AML-M4) and liver hydatidosis. Management is discussed. The patient had cystic echinococcosis (CE) of the liver that was classified as CE1 according to the system established by the World Health Organization's Informal Working Group on Echinococcosis. The patient underwent 3 months of treatment with agents that targeted the leukemia (daunorubicin, idarubicin, cytarabine, fludarabine) and its complications (amphotericin B, amphotericin B lipid complex, liposomal amphotericin B). Throughout this period, the size and the contents of the cyst did not change, Echinococcus titers remained unchanged, and the cyst classification remained CE1.  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