全文获取类型
收费全文 | 1024篇 |
免费 | 33篇 |
国内免费 | 1篇 |
专业分类
1058篇 |
出版年
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 | 26篇 |
2016年 | 41篇 |
2015年 | 38篇 |
2014年 | 60篇 |
2013年 | 67篇 |
2012年 | 88篇 |
2011年 | 85篇 |
2010年 | 60篇 |
2009年 | 49篇 |
2008年 | 72篇 |
2007年 | 48篇 |
2006年 | 62篇 |
2005年 | 60篇 |
2004年 | 59篇 |
2003年 | 65篇 |
2002年 | 41篇 |
2001年 | 7篇 |
2000年 | 5篇 |
1999年 | 5篇 |
1998年 | 8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1058条查询结果,搜索用时 15 毫秒
101.
Ogeturk M Kus I Kavakli A Oner J Kukner A Sarsilmaz M 《Cell biochemistry and function》2005,23(2):85-92
The aim of this study was to investigate possible protective effects of melatonin on carbon tetrachloride (CCl4)-induced renal damage in rats. A total of 24 animals were divided into three equal groups: the control rats received pure olive oil subcutaneously, rats in the second group were injected with CCl4 (0.5 ml kg-1, s.c. in olive oil) and rats in the third group were injected with CCl4 (0.5 ml kg-1) plus melatonin (25 mg kg-1, s.c. in 10% ethanol) every other day for 1 month. At the end of the experimental period, the animals were sacrificed and blood samples were collected. The kidneys were removed and weighed. Urea and creatinine levels were determined in blood samples. Histopathological examination of the kidney was performed using light microscopic methods. Administration of CCl4 significantly increased relative kidney weight (g per 100 g body weight) and decreased serum urea levels compared to controls (p<0.01). Melatonin treatment significantly (p<0.01) reduced relative kidney weight, and it produced a statistically equal (p=0.268) relative weight with the kidneys of control rats. CCl4 administration alone also caused histopathologically prominent damage in the kidney compared to the control group. Glomerular and tubular degeneration, interstitial mononuclear cell infiltration and fibrosis, vascular congestion around the tubules, and interstitial haemorrhage in perivascular areas were observed in the renal cortex and cortico-medullary border. However, the affect of CCl4 on the medulla was limited. Melatonin provided protection against CCl4-induced renal toxicity as was evident by histopathological evaluation. In view of the present findings, it is suggested that melatonin protects kidneys against CCl4 toxicity. 相似文献
102.
Ahmet?E.?KideysEmail author Nuray?Soydemir Elif?Eker Vladimir?Vladymyrov Dmitry?Soloviev Frederic?Melin 《Hydrobiologia》2005,543(1):159-168
Phytoplankton abundance, biomass and species composition of the Caspian Sea were evaluated by using samples collected from the Iranian (southern Caspian Sea) and southern Kazakhstan (eastern Caspian Sea) surface waters in March 2001. A total of 45 taxa were found in the samples (20 diatoms, 17 dinoflagellates and 8 others). Abundance and biomass of diatoms were high at the eastern stations, while dinoflagellates were dominant in terms of both biomass and abundance in the southern region. Average abundance and biomass were 40 000 ± 35 000 cell l−1 and 580 ± 690 μg l−1. The mean biomass value found here for the Middle and southern Caspian Sea in March are difficult to compare with the past due to limited information, but seems higher than previously registered values. Higher chlorophyll values were also apparent from the SeaWIFS images in 2001 compared to those in 1998. This is suggested to be due to decreased grazing of phytoplankton by zooplankton which is voraciously preyed by the recent invasive ctenophore Mnemiopsis leidyi. 相似文献
103.
104.
Protective agent, erdosteine, against cisplatin-induced hepatic oxidant injury in rats 总被引:5,自引:0,他引:5
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
105.
106.
Plant-based microarray data at the European Bioinformatics Institute. Introducing AtMIAMExpress, a submission tool for Arabidopsis gene expression data to ArrayExpress 下载免费PDF全文
Mukherjee G Abeygunawardena N Parkinson H Contrino S Durinck S Farne A Holloway E Lilja P Moreau Y Oezcimen A Rayner T Sharma A Brazma A Sarkans U Shojatalab M 《Plant physiology》2005,139(2):632-636
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
107.
108.
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
109.
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
110.
Semra?Mirici ?skender?Parmaks?z Sebahattin??zcanEmail author Cengiz?Sancak Serkan?Uranbey Ercüment?O.?Sar?han Ahmet?Gümü?cü Bilal?Gürbüz Ne?et?Arslan 《Plant Cell, Tissue and Organ Culture》2005,80(3):239-246
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