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   94篇
  免费   7篇
  2023年   2篇
  2022年   3篇
  2021年   1篇
  2020年   3篇
  2019年   3篇
  2018年   2篇
  2017年   5篇
  2016年   2篇
  2015年   6篇
  2014年   7篇
  2013年   10篇
  2012年   16篇
  2011年   9篇
  2010年   7篇
  2009年   4篇
  2008年   3篇
  2007年   5篇
  2006年   4篇
  2005年   1篇
  2004年   1篇
  2003年   2篇
  2002年   2篇
  2000年   1篇
  1999年   1篇
  1992年   1篇
排序方式: 共有101条查询结果,搜索用时 335 毫秒
61.
Juveniles of milkfish, Chanos chanos (Forsskal), were fed two independent supra dietary levels of vitamins C (500 and 1500 mg kg(-1) feed, T1 and T2) and E (50 and 150 mg kg(-1), T3 and T4). Milkfish fed diets with supra (in addition to the vitamins present in the control diet) and normal levels (T5 containing 90 and 1.2mg of vitamins C and E, respectively, kg(-1) of feed) of vitamins were immunized (ip) with formalin-killed Vibrio vulnificus (FKVV). Priming and booster antibody responses to the injected bacterin were significantly (P<0.05) better in the milkfish juveniles fed supra dietary levels. Survival response of the experimental fish fed supra dietary levels of vitamins (T1, T2 and T3) was significantly (P<0.01) better than that of the control set. Protective response against virulent bacterial challenge of the vaccinated fish fed vitamin-supplemented diets (T2 and T3) was better than the control (T5) and T1 and T4. Memory factor reflecting immunological memory was superior in the fish fed vitamin-supplemented diets. Diets supplemented with either 1500 mg of Vitamin C or 50mg of Vitamin E kg(-1) produced the best antibody responses, final survival and protective response upon challenge. No conclusive inferences could be drawn on the growth responses from the experiment.  相似文献   
62.
Globalization and women empowerment have led to stressful life among Indian women. This stress impairs women’s hormonal makeup and menstrual cycle, leading to infertility. National Family Health Survey-3 (NFHS-3) reports a decline in fertility status in India, indicating a rise in various infertility treatments involving hormonal interventions. No studies are available from India on the risk association link between maternal hormonal treatments and ASD. Hence, this study explores the association of maternal hormonal interventions with risk for ASD. Parents of 942 children (471 ASD and 471 controls) across 9 cities in India participated in the questionnaire-based study. The questionnaire was pilot tested and validated for its content and reliability as a psychometric instrument. Data collection was done at 70 centres through direct interaction with parents and with the help of trained staff. Statistical analysis of data was carried out using SAS 9.1.3. Out of the 471 ASD cases analysed, 58 mothers had undergone hormonal interventions (12.3%) while there were only 22 mothers among controls who underwent hormonal interventions (4.6%). According to logistic regression analysis maternal hormonal intervention (OR=2.24) was a significant risk factor for ASD.  相似文献   
63.
Good quality medical research generally requires not only an expertise in the chosen medical field of interest but also a sound knowledge of statistical methodology. The number of medical research articles which have been published in Indian medical journals has increased quite substantially in the past decade. The aim of this study was to collate all evidence on study design quality and statistical analyses used in selected leading Indian medical journals. Ten (10) leading Indian medical journals were selected based on impact factors and all original research articles published in 2003 (N = 588) and 2013 (N = 774) were categorized and reviewed. A validated checklist on study design, statistical analyses, results presentation, and interpretation was used for review and evaluation of the articles. Main outcomes considered in the present study were – study design types and their frequencies, error/defects proportion in study design, statistical analyses, and implementation of CONSORT checklist in RCT (randomized clinical trials). From 2003 to 2013: The proportion of erroneous statistical analyses did not decrease (χ2=0.592, Φ=0.027, p=0.4418), 25% (80/320) in 2003 compared to 22.6% (111/490) in 2013. Compared with 2003, significant improvement was seen in 2013; the proportion of papers using statistical tests increased significantly (χ2=26.96, Φ=0.16, p<0.0001) from 42.5% (250/588) to 56.7 % (439/774). The overall proportion of errors in study design decreased significantly (χ2=16.783, Φ=0.12 p<0.0001), 41.3% (243/588) compared to 30.6% (237/774). In 2013, randomized clinical trials designs has remained very low (7.3%, 43/588) with majority showing some errors (41 papers, 95.3%). Majority of the published studies were retrospective in nature both in 2003 [79.1% (465/588)] and in 2013 [78.2% (605/774)]. Major decreases in error proportions were observed in both results presentation (χ2=24.477, Φ=0.17, p<0.0001), 82.2% (263/320) compared to 66.3% (325/490) and interpretation (χ2=25.616, Φ=0.173, p<0.0001), 32.5% (104/320) compared to 17.1% (84/490), though some serious ones were still present. Indian medical research seems to have made no major progress regarding using correct statistical analyses, but error/defects in study designs have decreased significantly. Randomized clinical trials are quite rarely published and have high proportion of methodological problems.  相似文献   
64.
65.
Analogous to observations in RNA viruses such as human immunodeficiency virus, genetic variation associated with intrahost dengue virus (DENV) populations has been postulated to influence viral fitness and disease pathogenesis. Previous attempts to investigate intrahost genetic variation in DENV characterized only a few viral genes or a limited number of full-length genomes. We developed a whole-genome amplification approach coupled with deep sequencing to capture intrahost diversity across the entire coding region of DENV-2. Using this approach, we sequenced DENV-2 genomes from the serum of 22 Nicaraguan individuals with secondary DENV infection and captured ~75% of the DENV genome in each sample (range, 40 to 98%). We identified and quantified variants using a highly sensitive and specific method and determined that the extent of diversity was considerably lower than previous estimates. Significant differences in intrahost diversity were detected between genes and also between antigenically distinct domains of the Envelope gene. Interestingly, a strong association was discerned between the extent of intrahost diversity in a few genes and viral clade identity. Additionally, the abundance of viral variants within a host, as well as the impact of viral mutations on amino acid encoding and predicted protein function, determined whether intrahost variants were observed at the interhost level in circulating Nicaraguan DENV-2 populations, strongly suggestive of purifying selection across transmission events. Our data illustrate the value of high-coverage genome-wide analysis of intrahost diversity for high-resolution mapping of the relationship between intrahost diversity and clinical, epidemiological, and virological parameters of viral infection.  相似文献   
66.
Four lytic bacteriophages designated as φVh1, φVh2, φVh3, and φVh4 were isolated from commercial shrimp hatcheries, possessing broad spectrum of infectivity against luminescent Vibrio harveyi isolates, considering their potential as biocontrol agent of luminescent bacterial disease in shrimp hatcheries, and were characterized by electron microscopy, genomic analysis, restriction enzyme analysis (REA), and pulsed-field gel electrophoresis (PFGE). Three phages φVh1, φVh2, and φVh4 had an icosahedral head of 60-115 nm size with a long, noncontractile tail of 130-329 × 1-17 nm, belonged to the family Siphoviridae. φVh3 had an icosahedral head (72 ± 5 nm) with a short tail (27 × 12 nm) and belonged to Podoviridae. REA with DraI and PFGE of genomic DNA digested with ScaI and XbaI and cluster analysis of their banding patterns indicated that φVh3 was distinct from the other three siphophages. PFGE-based genome mean size of the four bacteriophages φVh1, φVh2, φVh3, and φVh4 was estimated to be about 85, 58, 64, and 107 kb, respectively. These phages had the property of generalized transduction as demonstrated by transduction with plasmid pHSG 396 with frequencies ranging from 4.1 × 10(-7) to 2 × 10(-9) per plaque-forming unit, suggesting a potential ecological role in gene transfer among aquatic vibrios.  相似文献   
67.
A fungal strain, Aspergillus terreus strain GA2, isolated from an agricultural field cultivating sweet sorghum, produced feruloyl esterase using maize bran. In order to obtain maximum yields of feruloyl esterase, the solid state fermentation (SSF) conditions for enzyme production were standardized. Effective feruloyl esterase production was observed with maize bran as substrate followed by wheat bran, coconut husk, and rice husk among the tested agro-waste crop residues. Optimum particle size of 0.71- 0.3 mm and moisture content of 80% favored enzyme production. Moreover, optimum feruloyl esterase production was observed at pH 6.0 and a temperature of 30 degrees C. Supplementation of potato starch (0.6%) as the carbon source and casein (1%) as the nitrogen source favored enzyme production. Furthermore, the culture produced the enzyme after 7 days of incubation when the C:N ratio was 5. Optimization of the SSF conditions revealed that maximum enzyme activity (1,162 U/gds) was observed after 7 days in a production medium of 80% moisture content and pH 6.0 containing 16 g maize bran [25% (w/v)] of particle size of 0.71-0.3 mm, 0.6% potato starch, 3.0% casein, and 64 ml of formulated basal salt solution. Overall, the enzyme production was enhanced by 3.2-fold as compared with un-optimized conditions.  相似文献   
68.

Introduction

Health research is one mechanism to improve population-level health and should generally match the health needs of populations. However, there have been limited data to assess the trends in national-level cardiovascular research output, even as cardiovascular disease [CVD] has become the leading cause of morbidity and mortality worldwide.

Materials and Methods

We performed a time trends analysis of cardiovascular research publications (1999–2008) downloaded from Web of Knowledge using a iteratively-tested cardiovascular bibliometric filter with >90% precision and recall. We evaluated cardiovascular research publications, five-year running actual citation indices [ACIs], and degree of international collaboration measured through the ratio of the fractional count of addresses from one country against all addresses for each publication.

Results and Discussion

Global cardiovascular publication volume increased from 40 661 publications in 1999 to 55 284 publications in 2008, which represents a 36% increase. The proportion of cardiovascular publications from high-income, Organization for Economic Cooperation and Development [OECD] countries declined from 93% to 84% of the total share over the study period. High-income, OECD countries generally had higher fractional counts, which suggest less international collaboration, than lower income countries from 1999–2008. There was an inverse relationship between cardiovascular publications and age-standardized CVD morbidity and mortality rates, but a direct, curvilinear relationship between cardiovascular publications and Human Development Index from 1999–2008.

Conclusions

Cardiovascular health research output has increased substantially in the past decade, with a greater share of citations being published from low- and middle-income countries. However, low- and middle-income countries with the higher burdens of cardiovascular disease continue to have lower research output than high-income countries, and thus require targeted research investments to improve cardiovascular health.  相似文献   
69.

Background

Proteases have been shown to degrade airway mucin proteins and to damage the epithelium impairing mucociliary clearance. There are increased proteases in the COPD airway but changes in protease-antiprotease balance and mucin degradation have not been investigated during the course of a COPD exacerbation. We hypothesized that increased protease levels would lead to mucin degradation in acute COPD exacerbations.

Methods

We measured neutrophil elastase (NE) and alpha 1 protease inhibitor (A1-PI) levels using immunoblotting, and conducted protease inhibitor studies, zymograms, elastin substrate assays and cigarette smoke condensate experiments to evaluate the stability of the gel-forming mucins, MUC5AC and MUC5B, before and 5–6 weeks after an acute pulmonary exacerbation of COPD (n = 9 subjects).

Results

Unexpectedly, mucin concentration and mucin stability were highest at the start of the exacerbation and restored to baseline after 6 weeks. Consistent with these data, immunoblots and zymograms confirmed decreased NE concentration and activity and increased A1-PI at the start of the exacerbation. After recovery there was an increase in NE activity and a decrease in A1-PI levels. In vitro, protease inhibitor studies demonstrated that serine proteases played a key role in mucin degradation. Mucin stability was further enhanced upon treating with cigarette smoke condensate (CSC).

Conclusion

There appears to be rapid consumption of secreted proteases due to an increase in antiproteases, at the start of a COPD exacerbation. This leads to increased mucin gel stability which may be important in trapping and clearing infectious and inflammatory mediators, but this may also contribute acutely to mucus retention.  相似文献   
70.
Abstract

Nonstructural protein 5B (NS5B), the RNA-dependent RNA polymerase of Hepatitis C Virus (HCV), plays a key role in viral amplification and is an attractive and most explored target for discovery of new therapeutic agents for Hepatitis C. Though safe and effective, NS5B inhibitors were launched in 2013 (Sovaldi) and 2014 (Harvoni, Viekira Pak), the high price tags of these medications limit their use among poor people in developing countries. Hence, still there exists a need for cost-effective and short duration anti-HCV agents especially those targeting niche patient population who were non-respondent to earlier therapies or with comorbid conditions. The present study describes the discovery of novel non-nucleoside (NNI) inhibitors of NS5B using a series of rational drug design techniques such as virtual screening, scaffold matching and molecular docking. 2D and 3D structure based virtual screening technique identified 300 hit compounds. Top 20 hits were screened out from identified hits using molecular docking technique. Four molecules, that are representative of 20 hits were evaluated for binding affinity under in vitro conditions using surface plasmon resonance-based assay and the results emphasized that compound with CoCoCo ID: 412075 could exhibit good binding response toward NS5B and could be a potential candidate as NS5B inhibitor.

Communicated by Ramaswamy H. Sarma  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