全文获取类型
收费全文 | 947篇 |
免费 | 41篇 |
国内免费 | 10篇 |
出版年
2023年 | 9篇 |
2022年 | 13篇 |
2021年 | 25篇 |
2020年 | 22篇 |
2019年 | 26篇 |
2018年 | 27篇 |
2017年 | 28篇 |
2016年 | 42篇 |
2015年 | 49篇 |
2014年 | 61篇 |
2013年 | 82篇 |
2012年 | 77篇 |
2011年 | 82篇 |
2010年 | 56篇 |
2009年 | 44篇 |
2008年 | 49篇 |
2007年 | 27篇 |
2006年 | 35篇 |
2005年 | 37篇 |
2004年 | 22篇 |
2003年 | 23篇 |
2002年 | 17篇 |
2001年 | 8篇 |
2000年 | 4篇 |
1999年 | 5篇 |
1998年 | 10篇 |
1995年 | 4篇 |
1994年 | 5篇 |
1993年 | 6篇 |
1992年 | 10篇 |
1991年 | 3篇 |
1990年 | 4篇 |
1989年 | 5篇 |
1987年 | 4篇 |
1986年 | 4篇 |
1985年 | 4篇 |
1984年 | 6篇 |
1983年 | 3篇 |
1981年 | 3篇 |
1980年 | 3篇 |
1978年 | 3篇 |
1977年 | 3篇 |
1976年 | 3篇 |
1975年 | 7篇 |
1974年 | 3篇 |
1973年 | 5篇 |
1972年 | 3篇 |
1964年 | 3篇 |
1958年 | 3篇 |
1957年 | 2篇 |
排序方式: 共有998条查询结果,搜索用时 46 毫秒
51.
Avinash M. Veerappa Sangeetha Vishweswaraiah Kusuma Lingaiah Megha Murthy Raviraj V. Suresh Dinesh S. Manjegowda Nallur B. Ramachandra 《PloS one》2015,10(4)
Global spectrum of CNVs is required to catalog variations to provide a high-resolution on the dynamics of genome-organization and human migration. In this study, we performed genome-wide genotyping using high-resolution arrays and identified 44,109 CNVs from 1,715 genomes across 12 populations. The study unraveled the force of independent evolutionary dynamics on genome-organizational plasticity across populations. We demonstrated the use of CNV tool to study human migration and identified a second major settlement establishing new migration routes in addition to existing ones. 相似文献
52.
Xiaoyu Jiang Liya Yuan John A. Engelbach Jeremy Cates Carlos J. Perez-Torres Feng Gao Dinesh Thotala Robert E. Drzymala Robert E. Schmidt Keith M. Rich Dennis E. Hallahan Joseph J. H. Ackerman Joel R. Garbow 《PloS one》2015,10(10)
Purpose
To develop a Gamma Knife-based mouse model of late time-to-onset, cerebral radiation necrosis (RN) with serial evaluation by magnetic resonance imaging (MRI) and histology.Methods and Materials
Mice were irradiated with the Leksell Gamma Knife® (GK) PerfexionTM (Elekta AB; Stockholm, Sweden) with total single-hemispheric radiation doses (TRD) of 45- to 60-Gy, delivered in one to three fractions. RN was measured using T2-weighted MR images, while confirmation of tissue damage was assessed histologically by hematoxylin & eosin, trichrome, and PTAH staining.Results
MRI measurements demonstrate that TRD is a more important determinant of both time-to-onset and progression of RN than fractionation. The development of RN is significantly slower in mice irradiated with 45-Gy than 50- or 60-Gy, where RN development is similar. Irradiated mouse brains demonstrate all of the pathologic features observed clinically in patients with confirmed RN. A semi-quantitative (0 to 3) histologic grading system, capturing both the extent and severity of injury, is described and illustrated. Tissue damage, as assessed by a histologic score, correlates well with total necrotic volume measured by MRI (correlation coefficient = 0.948, with p<0.0001), and with post-irradiation time (correlation coefficient = 0.508, with p<0.0001).Conclusions
Following GK irradiation, mice develop late time-to-onset cerebral RN histology mirroring clinical observations. MR imaging provides reliable quantification of the necrotic volume that correlates well with histologic score. This mouse model of RN will provide a platform for mechanism of action studies, the identification of imaging biomarkers of RN, and the development of clinical studies for improved mitigation and neuroprotection. 相似文献53.
Tsuzuki Y Nguyen TK Garud DR Kuberan B Koketsu M 《Bioorganic & medicinal chemistry letters》2010,20(24):7269-7273
Various 4-deoxy-4-fluoro-xylosides were prepared using click chemistry for evaluating their potential utility as inhibitors of glycosaminoglycan biosynthesis. 2,3-Di-O-benzoyl-4-deoxy-4-fluoro-β-D-xylopyranosylazide, obtained from L-arabinopyranose by six steps, was treated with a wide variety of azide-reactive triple bond-containing hydrophobic agents in the presence of Cu(2+) salt/ascorbic acid, a step known as click chemistry. After click chemistry, benzoylated derivatives were deprotected under Zemplén conditions to obtain 4-deoxy-4-fluoro-xyloside derivatives. A mixture of α:β-isomers of twelve derivatives were then separated on a reverse phase C18 column using HPLC and the resulting twenty four 4-deoxy-4-fluoro-xylosides were evaluated for their ability to inhibit glycosaminoglycan biosynthesis in endothelial cells. We identified two xyloside derivatives that selectively inhibit heparan sulfate and chondroitin sulfate/derman sulfate biosynthesis without affecting cell viability. These novel derivatives can potentially be used to define the biological actions of proteoglycans in model organisms and also as therapeutic agents to combat various human diseases in which glycosaminoglycans participate. 相似文献
54.
Sheelendra Pratap Singh Dinesh K. Yadav Preeti Rawat Rakesh Maurya Girish Kumar Jain 《Journal of chromatography. B, Analytical technologies in the biomedical and life sciences》2010,878(3-4):391-397
A new simple, rapid, sensitive and accurate quantitative detection method using liquid chromatography coupled with tandem mass spectrometry (LC–MS/MS) for the measurement of formononetin (FMN) and daidzein (DZN) levels in rat plasma is described. Analytes were separated on a Supelco Discovery C18 (4.6 × 50 mm, 5.0 μm) column with acetonitrile: methanol (50:50, v/v) and 0.1% acetic acid in the ratio of 90:10 (v/v) as a mobile phase. The method was proved to be accurate and precise at linearity range of 5–100 ng/mL with a correlation coefficient (r) of ≥0.996. The intra- and inter-day assay precision ranged from 1.66–6.82% and 1.87–6.75%, respectively; and intra- and inter-day assay accuracy was between 89.98–107.56% and 90.54–105.63%, respectively for both the analytes. The lowest quantitation limit for FMN and DZN was 5.0 ng/mL in 0.1 mL of rat plasma. Practical utility of this new LC–MS/MS method was demonstrated in a pharmacokinetic study in rats following intravenous administration of FMN. 相似文献
55.
56.
Comparative analysis of the grain proteome fraction in barley genotypes with contrasting salinity tolerance during germination 总被引:1,自引:0,他引:1
57.
Chintamani Pranjal Kulshreshtha Anurupa Chakraborty LC Singh Ashwani K Mishra Dinesh Bhatnagar Sunita Saxena 《World journal of surgical oncology》2010,8(1):1-9
Voltage gated potassium channels have been extensively studied in relation to cancer. In this review, we will focus on the role of two potassium channels, Ether à-go-go (Eag), Human ether à-go-go related gene (HERG), in cancer and their potential therapeutic utility in the treatment of cancer. Eag and HERG are expressed in cancers of various organs and have been implicated in cell cycle progression and proliferation of cancer cells. Inhibition of these channels has been shown to reduce proliferation both in vitro and vivo studies identifying potassium channel modulators as putative inhibitors of tumour progression. Eag channels in view of their restricted expression in normal tissue may emerge as novel tumour biomarkers. 相似文献
58.
Service records of 253 mares (1181 mare-years) spanning over 7 consecutive years, from nine organized Thoroughbred stud farms, situated in the subtropical northwestern India were retrospectively analyzed to assess their reproductive performance. The overall per cycle pregnancy rate at Day 16 and overall foaling rates were 50.30% and 68.95%, respectively, and were significantly higher in mares aged 3–7 years than ≥18 years old mares. The late embryonic losses (9.86%) that occurred between Days 16 and 39 post-ovulation contributed more than 50% of the overall detected pregnancy losses (19.11%). The overall percent detected pregnancy losses were lower in mares at ages 3–7 years compared to those at ages ≥18 years (14.78% vs. 46.43%, respectively; P < 0.0001). Chronic barren and habitual aborter mares tended to affect reproductive efficiency of mares. Fifty percent of the mares that experienced ≥2 consecutive abortions or barren years, again stayed aborted or barren in the next seasons, respectively. No effect of numbers of matings per oestrus was observed on overall fertility. Neither the induction of oestrus nor ovulation by exogenous hormonal treatment had any effect on most of the analyzed reproductive parameters. Regarding breeding month or years, the reproductive efficiency did not differ significantly. The incidence of multiple pregnancies was 5.40% and percent late embryonic loses were higher (P = 0.0016) in twin (21.98%) than singleton (8.64%) pregnancies. In conclusion, comparatively lower fertility rates were recorded in Thoroughbred mares bred under Indian subtropical climatic conditions than those reported from temperate regions that might be due to difference in breeding management rather than prevailing environment. 相似文献
59.
Discharge of heavy metals from metal processing industries is known to have adverse effects on the environment. Conventional treatment technologies for removal of heavy metals from aqueous solution are not economical and generate huge quantity of toxic chemical sludge. Biosorption of heavy metals by metabolically inactive non-living biomass of microbial or plant origin is an innovative and alternative technology for removal of these pollutants from aqueous solution. Due to unique chemical composition biomass sequesters metal ions by forming metal complexes from solution and obviates the necessity to maintain special growth-supporting conditions. Biomass of Aspergillus niger, Penicillium chrysogenum, Rhizopus nigricans, Ascophyllum nodosum, Sargassum natans, Chlorella fusca, Oscillatoria anguistissima, Bacillus firmus and Streptomyces sp. have highest metal adsorption capacities ranging from 5 to 641 mg g(-1) mainly for Pb, Zn, Cd, Cr, Cu and Ni. Biomass generated as a by-product of fermentative processes offers great potential for adopting an economical metal-recovery system. The purpose of this paper is to review the available information on various attributes of utilization of microbial and plant derived biomass and explores the possibility of exploiting them for heavy metal remediation. 相似文献
60.
Fröhlich J Koustiane C Kämpfer P Rosselló-Mora R Valens M Berchtold M Kuhnigk T Hertel H Maheshwari DK König H 《Systematic and applied microbiology》2007,30(1):68-74
Wood-eating termites feed on a diet highly deficient in nitrogen. They must complement their diet with the aid of nitrogen-fixing bacteria. Nitrogen fixation in the gut has been demonstrated, but information about nitrogen-fixing bacteria in pure culture is scarce. From the higher termite Nasutitermes nigriceps the symbiotic bacterial strain M3A was isolated, which thrives in the hindgut contents. The Gram-negative strain exhibited similarities to the species of the genus Ensifer (including Sinorhizobium) on the basis of morphological and physiological/biochemical features. The 16S rRNA gene analysis showed the highest sequence similarity of the isolate M3A to Ensifer adhaerens (>99%; ATCC 33499). The DNA-DNA hybridization revealed a similarity of 66% with E. adhaerens (NCIMB12342(T)). In contrast to the type strain the isolate M3A possesses the capacity to nodulate plant roots. This is the first report on the detailed identification of a rhizobia-related strain from the intestinal tract of animals. Strain M3A has been deposited with two culture collections (DSM10169; ATCC BAA-396). 相似文献