全文获取类型
收费全文 | 142篇 |
免费 | 6篇 |
专业分类
148篇 |
出版年
2023年 | 1篇 |
2021年 | 3篇 |
2019年 | 1篇 |
2018年 | 1篇 |
2017年 | 2篇 |
2016年 | 6篇 |
2015年 | 4篇 |
2014年 | 2篇 |
2013年 | 4篇 |
2012年 | 10篇 |
2011年 | 10篇 |
2010年 | 11篇 |
2009年 | 3篇 |
2008年 | 8篇 |
2007年 | 9篇 |
2006年 | 4篇 |
2005年 | 7篇 |
2004年 | 5篇 |
2003年 | 4篇 |
2002年 | 2篇 |
2001年 | 3篇 |
2000年 | 2篇 |
1999年 | 2篇 |
1998年 | 2篇 |
1997年 | 1篇 |
1996年 | 1篇 |
1994年 | 1篇 |
1993年 | 4篇 |
1992年 | 1篇 |
1991年 | 1篇 |
1990年 | 3篇 |
1989年 | 2篇 |
1987年 | 3篇 |
1986年 | 3篇 |
1984年 | 1篇 |
1983年 | 6篇 |
1982年 | 7篇 |
1981年 | 2篇 |
1980年 | 1篇 |
1979年 | 1篇 |
1973年 | 2篇 |
1972年 | 1篇 |
1969年 | 1篇 |
排序方式: 共有148条查询结果,搜索用时 15 毫秒
41.
Crucitti T Fransen K Maharaj R Tenywa T Massinga Loembé M Murugavel KG Mendonca K Abdellati S Beelaert G Van Damme L 《PloS one》2010,5(10):e13592
Background
Over the last decade several phase III microbicides trials have been conducted in developing countries. However, laboratories in resource constrained settings do not always have the experience, infrastructure, and the capacity to deliver laboratory data meeting the high standards of clinical trials. This paper describes the design and outcomes of a laboratory quality assurance program which was implemented during a phase III clinical trial evaluating the efficacy of the candidate microbicide Cellulose Sulfate 6% (CS) [1].Methodology
In order to assess the effectiveness of CS for HIV and STI prevention, a phase III clinical trial was conducted in 5 sites: 3 in Africa and 2 in India. The trial sponsor identified an International Central Reference Laboratory (ICRL), responsible for the design and management of a quality assurance program, which would guarantee the reliability of laboratory data. The ICRL provided advice on the tests, assessed local laboratories, organized trainings, conducted supervision visits, performed re-tests, and prepared control panels. Local laboratories were provided with control panels for HIV rapid tests and Chlamydia trachomatis/Neisseria gonorrhoeae (CT/NG) amplification technique. Aliquots from respective control panels were tested by local laboratories and were compared with results obtained at the ICRL.Results
Overall, good results were observed. However, discordances between the ICRL and site laboratories were identified for HIV and CT/NG results. One particular site experienced difficulties with HIV rapid testing shortly after study initiation. At all sites, DNA contamination was identified as a cause of invalid CT/NG results. Both problems were timely detected and solved. Through immediate feedback, guidance and repeated training of laboratory staff, additional inaccuracies were prevented.Conclusions
Quality control guidelines when applied in field laboratories ensured the reliability and validity of final study data. It is essential that sponsors provide adequate resources for implementation of such comprehensive technical assessment and monitoring systems.Trial Registration
ClinicalTrials.gov and Current Controlled Trials NCT00153777ISRCTN95638385 相似文献42.
R. Maharaj E. Rumbak W. A. Jones S. M. Robb F. T. Robb D. R. Woods 《Archives of microbiology》1989,152(6):542-549
The nucleotide sequence of a 4 kb fragment containing the Vibrio alginolyticus glnA, ntrB and ntrC genes was determined. The upstream region of the glnA gene contained tandem promoters. The upstream promoter resembled the consensus sequence for Escherichia coli 70 promoters whereas the presumptive downstream promoter showed homology with nitrogen regulated promoters. Four putative NRI binding sites were located between the tandem promoters. The ntrB gene was preceded by a single presumptive NRI binding site. The ntrC gene was located 45 base pairs downstream from the ntrB gene. The V. alginolyticus ntrB and ntrC genes were able to complement ntrB, ntrC deletions in E. coli.Abbreviations bp
base pair(s)
- CAP
catabolite-activating protein
- GS
glutamine synthetase
- kb
kilobase(s)
- ORF
open reading frame
- SD
Shine-Dalgarno 相似文献
43.
Seventy-three patients were studied after ingesting a liquid glucose meal, tagged with 113Indium. Nineteen of these patients were awaiting surgery for their duodenal ulcer, while 54 were studied postoperatively, 25 of whom experienced troublesome postprandial (dumping) symptoms in their daily lives. The radioactive marker emptied significantly faster in the symptomatic patients than in the symptomfree, pre and post-operative groups (initial emptying rate 3.45 ± 0.23, compared with 1.16 ± 0.19 and 1.27 ± 0.15% fall in counts/min respectively; p < 0.01). Initial (20 min) rises in the plasma concentrations of neurotensin-like immunoreactivity measured during the test correlated significantly with the rate of gastric emptying in all patients, being greatest in patients with dumping symptoms. Physiological concentrations of neurotensin have been shown to delay gastric emptying. The excessive rise in plasma neurotensin-like immunoreactivity in patients with dumping symptoms, presumably occuring as a result of the rapid passage of nutrients to the neurotensin-rich ileum, may possibly have a compensatory role in slowing further emptying from the stomach. 相似文献
44.
Background
Studying diversity and distribution patterns of species along elevational gradients and understanding drivers behind these patterns is central to macroecology and conservation biology. A number of studies on biogeographic gradients are available for terrestrial ecosystems, but freshwater ecosystems remain largely neglected. In particular, we know very little about the species richness gradients and their drivers in the Himalaya, a global biodiversity hotspot.Methodology/Principal Findings
We collated taxonomic and distribution data of fish species from 16 freshwater Himalayan rivers and carried out empirical studies on environmental drivers and fish diversity and distribution in the Teesta river (Eastern Himalaya). We examined patterns of fish species richness along the Himalayan elevational gradients (50–3800 m) and sought to understand the drivers behind the emerging patterns. We used generalized linear models (GLM) and generalized additive models (GAM) to examine the richness patterns; GLM was used to investigate relationship between fish species richness and various environmental variables. Regression modelling involved stepwise procedures, including elimination of collinear variables, best model selection, based on the least Akaike’s information criterion (AIC) and the highest percentage of deviance explained (D2). This maiden study on the Himalayan fishes revealed that total and non-endemic fish species richness monotonously decrease with increasing elevation, while endemics peaked around mid elevations (700–1500 m). The best explanatory model (synthetic model) indicated that water discharge is the best predictor of fish species richness patterns in the Himalayan rivers.Conclusions/Significance
This study, carried out along one of the longest bioclimatic elevation gradients of the world, lends support to Rapoport’s elevational rule as opposed to mid domain effect hypothesis. We propose a species-discharge model and contradict species-area model in predicting fish species richness. We suggest that drivers of richness gradients in terrestrial and aquatic ecosystems are likely to be different. These studies are crucial in context of the impacts of unprecedented on-going river regulation on fish diversity and distribution in the Himalaya. 相似文献45.
46.
47.
48.
49.
Differential apoptotic response to ionizing radiation in subpopulations of human white blood cells. 总被引:2,自引:0,他引:2
R C Wilkins D Wilkinson H P Maharaj P V Bellier M B Cybulski J R N McLean 《Mutation research》2002,513(1-2):27-36
The purpose of this paper is to characterize the apoptotic response of various subpopulations of human white blood cells after in vitro exposure to ionizing radiation using the modified neutral comet assay (MNCA). White blood cells, isolated from human whole blood, were fractionated into granulocytes and mononuclear cells which were further separated into B-cells, natural killer (NK) cells, and CD4(+) and CD8(+) T-cells. The separated fractions were exposed to low doses of X-rays and then MNCA was used to measure the apoptotic fraction (AF) at different time points in irradiated and unirradiated aliquots of sorted cultures. The spontaneous AF in unirradiated control cells was the most critical determinant of whether an apoptotic response could be detected in irradiated cells. When cultured in isolation granulocytes and B-cells had the highest background AF, with NK cells having the next highest. CD4(+) and CD8(+) T-cells had a low, stable, spontaneous AF which gave them the highest signal-to-noise ratio. Although B-cells demonstrated the highest radiation-induced apoptotic response to 1Gy of X-rays, CD8(+) T-cells were the most radiation-responsive lymphocytes due to their low spontaneous AF. By generating dose response curves for CD4(+) and CD8(+) T-cells, the sensitivity of the MNCA for detecting apoptosis in these two cell types was also examined. 相似文献
50.
Fatoba Abiodun J. Adeleke Victoria T. Maharaj Leah Okpeku Moses Adeniyi Adebayo A. Adeleke Matthew A. 《International journal of peptide research and therapeutics》2021,27(4):2183-2198
International Journal of Peptide Research and Therapeutics - Enterococcus faecium has emerged as the fourth most commonly isolated nosocomial pathogen due to its resistance to commonly used... 相似文献