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   924篇
  免费   26篇
  2023年   3篇
  2022年   3篇
  2021年   14篇
  2020年   6篇
  2019年   9篇
  2018年   15篇
  2017年   6篇
  2016年   17篇
  2015年   33篇
  2014年   40篇
  2013年   61篇
  2012年   75篇
  2011年   54篇
  2010年   33篇
  2009年   30篇
  2008年   34篇
  2007年   57篇
  2006年   49篇
  2005年   44篇
  2004年   40篇
  2003年   47篇
  2002年   31篇
  2001年   17篇
  2000年   16篇
  1999年   14篇
  1998年   9篇
  1997年   9篇
  1996年   5篇
  1995年   10篇
  1994年   10篇
  1993年   6篇
  1992年   17篇
  1991年   10篇
  1990年   7篇
  1989年   17篇
  1988年   9篇
  1987年   13篇
  1986年   7篇
  1985年   13篇
  1984年   12篇
  1983年   7篇
  1982年   4篇
  1981年   4篇
  1980年   3篇
  1979年   4篇
  1978年   5篇
  1977年   4篇
  1974年   5篇
  1964年   5篇
  1961年   1篇
排序方式: 共有950条查询结果,搜索用时 140 毫秒
21.
Curcumin, a dietary polyphenol, has shown a potential to act on the symptoms of neurodegenerative disorders, including Alzheimer’s and Parkinson’s diseases, as a consequence of its antioxidant, anti-inflammatory and anti-protein aggregation properties. Unfortunately, curcumin undergoes rapid degradation at physiological pH into ferulic acid, vanillin and dehydrozingerone, making it an unlikely drug candidate. Here, we evaluated the ability of some curcumin by-products: dehydrozingerone (1), its O-methyl derivative (2), zingerone (3), and their biphenyl analogues (4–6) to interact with α-synuclein (AS), using CD and fluorescence spectroscopy. In addition, the antioxidant properties and the cytoprotective effects in rat pheochromocytoma (PC12) cells prior to intoxication with H2O2, MPP+ and MnCl2 were examined while the Congo red assay was used to evaluate the ability of these compounds to prevent aggregation of AS. We found that the biphenyl zingerone analogue (6) interacts with high affinity with AS and also displays the best antioxidant properties while the biphenyl analogues of dehydrozingerone (4) and of O-methyl-dehydrozingerone (5) are able to partially inhibit the aggregation process of AS, suggesting the potential role of a hydroxylated biphenyl scaffold in the design of AS aggregation inhibitors.  相似文献   
22.

Background

Optimized preventive strategies are needed to reach the objective of eliminating pediatric AIDS. This study aimed to define the determinants of residual HIV transmission in the context of maternal antiretroviral therapy (ART) administration to pregnant women, to assess infant safety of this strategy, and to evaluate its impact on maternal disease.

Methodology/Principal Findings

A total of 311 HIV-infected pregnant women were enrolled in Malawi in an observational study and received a nevirapine-based regimen from week 25 of gestation until 6 months after delivery (end of breastfeeding period) if their CD4+ count was > 350/mm3 at baseline (n = 147), or indefinitely if they met the criteria for treatment (n. 164). Mother/child pairs were followed until 2 years after delivery. The Kaplan-Meier method was used to estimate HIV transmission, maternal disease progression, and survival at 24 months. The rate of HIV infant infection was 3.2% [95% confidence intervals (CI) 1.0-5.4]. Six of the 8 transmissions occurred among mothers with baseline CD4+ count > 350/mm3. HIV-free survival of children was 85.8% (95% CI 81.4-90.1). Children born to mothers with baseline CD4+ count < 350/mm3 were at increased risk of death (hazard ratio 2.6, 95% CI 1.1-6.1). Among women who had stopped treatment the risk of progression to CD4+ count < 350/mm3 was 20.6% (95% CI 9.2-31.9) by 18 months of drug discontinuation.

Conclusions

HIV transmission in this cohort was rare however, it occurred in a significative proportion among women with high CD4+ counts. Strategies to improve treatment adherence should be implemented to further reduce HIV transmission. Mortality in the uninfected exposed children was the major determinant of HIV-free survival and was associated to maternal disease stage. Given the considerable proportion of women reaching the criteria for treatment within 18 months of drug discontinuation, life-long ART administration to HIV-infected women should be considered.  相似文献   
23.
24.

Objective

To estimate the lifetime cost utility of two antiretroviral regimens (once-daily atazanavir plus ritonavir [ATV+r] versus twice-daily lopinavir/ritonavir [LPV/r]) in Italian human immunodeficiency virus (HIV)-infected patients naïve to treatment.

Design

With this observational retrospective study we collected the clinical data of a cohort of HIV-infected patients receiving first-line treatment with LPV/r or ATV+r.

Methodology

A Markov microsimulation model including direct costs and health outcomes of first- and second-line highly active retroviral therapy was developed from a third-party (Italian National Healthcare Service) payer’s perspective. Health and monetary outcomes associated with the long-term use of ATV+r and LPV/r regimens were evaluated on the basis of eight health states, incidence of diarrhoea and hyperbilirubinemia, AIDS events, opportunistic infections, coronary heart disease events and, for the first time in an economic evaluation, chronic kidney disease (CKD) events. In order to account for possible deviations between real-life data and randomised controlled trial results, a second control arm (ATV+r 2) was created with differential transition probabilities taken from the literature.

Results

The average survival was 24.061 years for patients receiving LPV/r, 24.081 and 24.084 for those receiving ATV+r 1 and 2 respectively. The mean quality-adjusted life-years (QALYs) were higher for the patients receiving LPV/r than those receiving ATV+r (13.322 vs. 13.060 and 13.261 for ATV+r 1 and 2). The cost-utility values were 15,310.56 for LPV/r, 15,902.99 and 15,524.85 for ATV+r 1 and 2.

Conclusions

Using real-life data, the model produced significantly different results compared with other studies. With the innovative addition of an evaluation of CKD events, the model showed a cost-utility value advantage for twice-daily LPV/r over once-daily ATV+r, thus providing evidence for its continued use in the treatment of HIV.  相似文献   
25.

Background

An integrated strategy of intervention against tsetse flies was implemented in the Upper West Region of Ghana (9.62°–11.00° N, 1.40°–2.76° W), covering an area of ≈18,000 km2 within the framework of the Pan-African Tsetse and Trypanosomosis Eradication Campaign. Two species were targeted: Glossina tachinoides and Glossina palpalis gambiensis.

Methodology/Principal Findings

The objectives were to test the potentiality of the sequential aerosol technique (SAT) to eliminate riverine tsetse species in a challenging subsection (dense tree canopy and high tsetse densities) of the total sprayed area (6,745 km2) and the subsequent efficacy of an integrated strategy including ground spraying (≈100 km2), insecticide treated targets (20,000) and insecticide treated cattle (45,000) in sustaining the results of tsetse suppression in the whole intervention area. The aerial application of low-dosage deltamethrin aerosols (0.33–0.35 g a.i/ha) was conducted along the three main rivers using five custom designed fixed-wings Turbo thrush aircraft. The impact of SAT on tsetse densities was monitored using 30 biconical traps deployed from two weeks before until two weeks after the operations. Results of the SAT monitoring indicated an overall reduction rate of 98% (from a pre-intervention mean apparent density per trap per day (ADT) of 16.7 to 0.3 at the end of the fourth and last cycle). One year after the SAT operations, a second survey using 200 biconical traps set in 20 sites during 3 weeks was conducted throughout the intervention area to measure the impact of the integrated control strategy. Both target species were still detected, albeit at very low densities (ADT of 0.27 inside sprayed blocks and 0.10 outside sprayed blocks).

Conclusions/Significance

The SAT operations failed to achieve elimination in the monitored section, but the subsequent integrated strategy maintained high levels of suppression throughout the intervention area, which will contribute to improving animal health, increasing animal production and fostering food security.  相似文献   
26.
27.
28.
Summary

The A. notes some new localities of Latium in which he has found several plants interesting for their rarity, but chiefly for their phytogeographical features in reference to the stations in which these species were found. The following plants are for Latium as new: Bifora radians M. B., Cuscuta pentagona Eng., Lippia nodiflora Rich., Galinsoga parviflora Cav., Lapsana hirta Ten.  相似文献   
29.
Phytochemistry Reviews - Phytoalimurgy is a term that derives from Greek and Latin by combination of the words φυτόν, which meaning plant, and alimenta urgentia, indicating...  相似文献   
30.
Most cases of medulloblastoma (MB) occur in young children. While the overall survival rate can be relatively high, current treatments combining surgery, chemo‐ and radiotherapy are very destructive for patient development and quality of life. Moreover, aggressive forms and recurrences of MB cannot be controlled by classical therapies. Therefore, new therapeutic approaches yielding good efficacy and low toxicity for healthy tissues are required to improve patient outcome. Cancer cells sustain their proliferation by optimizing their nutrient uptake capacities. The L‐type amino acid transporter 1 (LAT1) is an essential amino acid carrier overexpressed in aggressive human cancers that was described as a potential therapeutic target. In this study, we investigated the therapeutic potential of JPH203, a LAT1‐specific pharmacological inhibitor, on two independent MB cell lines belonging to subgroups 3 (HD‐MB03) and Shh (DAOY). We show that while displaying low toxicity towards normal cerebral cells, JPH203 disrupts AA homeostasis, mTORC1 activity, proliferation and survival in MB cells. Moreover, we demonstrate that a long‐term treatment with JPH203 does not lead to resistance in MB cells. Therefore, this study suggests that targeting LAT1 with JPH203 is a promising therapeutic approach for MB treatment.  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