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   1522篇
  免费   93篇
  国内免费   10篇
耳鼻咽喉   2篇
儿科学   64篇
妇产科学   19篇
基础医学   196篇
口腔科学   19篇
临床医学   185篇
内科学   282篇
皮肤病学   35篇
神经病学   118篇
特种医学   74篇
外科学   299篇
综合类   20篇
一般理论   1篇
预防医学   81篇
眼科学   62篇
药学   89篇
肿瘤学   79篇
  2024年   4篇
  2023年   29篇
  2022年   34篇
  2021年   56篇
  2020年   39篇
  2019年   51篇
  2018年   48篇
  2017年   34篇
  2016年   51篇
  2015年   73篇
  2014年   78篇
  2013年   110篇
  2012年   151篇
  2011年   164篇
  2010年   78篇
  2009年   68篇
  2008年   111篇
  2007年   64篇
  2006年   85篇
  2005年   80篇
  2004年   63篇
  2003年   59篇
  2002年   33篇
  2001年   8篇
  2000年   8篇
  1999年   9篇
  1998年   6篇
  1997年   5篇
  1996年   3篇
  1995年   2篇
  1993年   1篇
  1991年   1篇
  1988年   1篇
  1986年   2篇
  1982年   3篇
  1975年   1篇
  1963年   1篇
  1956年   1篇
  1955年   1篇
  1949年   2篇
  1948年   1篇
  1947年   1篇
  1946年   2篇
  1944年   1篇
  1940年   1篇
  1903年   1篇
排序方式: 共有1625条查询结果,搜索用时 0 毫秒
1.
2.
3.
We evaluated nucleic acid amplification testing (NAAT) for Zika virus on whole-blood specimens compared with NAAT on serum and urine specimens among asymptomatic pregnant women during the 2015–2016 Puerto Rico Zika outbreak. Using NAAT, more infections were detected in serum and urine than in whole blood specimens.  相似文献   
4.
BackgroundInjury to kidney podocytes often results in chronic glomerular disease and consecutive nephron malfunction. For most glomerular diseases, targeted therapies are lacking. Thus, it is important to identify novel signaling pathways contributing to glomerular disease. Neurotrophic tyrosine kinase receptor 3 (TrkC) is expressed in podocytes and the protein transmits signals to the podocyte actin cytoskeleton.MethodsNephron-specific TrkC knockout (TrkC-KO) and nephron-specific TrkC-overexpressing (TrkC-OE) mice were generated to dissect the role of TrkC in nephron development and maintenance.ResultsBoth TrkC-KO and TrkC-OE mice exhibited enlarged glomeruli, mesangial proliferation, basement membrane thickening, albuminuria, podocyte loss, and aspects of FSGS during aging. Igf1 receptor (Igf1R)–associated gene expression was dysregulated in TrkC-KO mouse glomeruli. Phosphoproteins associated with insulin, erb-b2 receptor tyrosine kinase (Erbb), and Toll-like receptor signaling were enriched in lysates of podocytes treated with the TrkC ligand neurotrophin-3 (Nt-3). Activation of TrkC by Nt-3 resulted in phosphorylation of the Igf1R on activating tyrosine residues in podocytes. Igf1R phosphorylation was increased in TrkC-OE mouse kidneys while it was decreased in TrkC-KO kidneys. Furthermore, TrkC expression was elevated in glomerular tissue of patients with diabetic kidney disease compared with control glomerular tissue.ConclusionsOur results show that TrkC is essential for maintaining glomerular integrity. Furthermore, TrkC modulates Igf-related signaling in podocytes.  相似文献   
5.
Recombinant Sendai virus vectors (SeVV) have become an attractive tool for basic virological as well as for gene transfer studies. However, to (i) reduce the cellular injury induced by basic recombinant SeV vectors (encoding all six SeV genes as being present in SeV wild-type (wt) genomes) and to (ii) improve SeV vector safety, deletions of viral genes are necessary for the construction of superior SeVV generations. As a strong expression system recombinant replication-incompetent adenoviruses, coding for SeV proteins hemagglutinin-neuraminidase (HN), fusion (F), or matrix (M), were generated and successfully employed for the propagation of single gene deleted (DeltaHN, DeltaF, DeltaM) recombinant SeVV. Further investigations of the propagation procedures required for single gene deleted recombinant SeVV demonstrated (i) modifications of the cell culture medium composition as well as (ii) incubation with vitamin E as crucial steps for the enhancement of SeVV-DeltaHN, -DeltaF, or -DeltaM viral particle yield. Such optimized propagation procedures even led to a successful propagation of HN-deleted viral particles (SeVV-DeltaHN), which has not been reported before.  相似文献   
6.
Background The anti-inflammatory drug etanercept may be an effective therapeutic agent in diabetic retinopathy. In order to further evaluate its potential, the pharmacokinetics and safety of this drug after intravitreal delivery were investigated.Methods After intravitreal administration of etanercept in rabbits, clinical examination, electroretinography (ERG), visually evoked potentials (VEP) and histology were evaluated. The pharmacokinetics and distribution of etanercept were analyzed using fluorescence-coupled protein at 0, 2, 4, and 8 weeks after injection in vitreous, retina, and choroid.Results No adverse effects and signs of toxicity were found. Etanercept showed peak concentrations after 4 weeks in the retina and choroid.Conclusions Intravitreally delivered etanercept is safe and results in high concentrations in the retina and choroid over a long period of time.  相似文献   
7.
8.
Let's Remember Corky, Fine, Polly Delson, Shaker Heights, Ohio, 1981. Paperback, unpaged, $4.75.

The Tenth Good Thing about Barney, Viorst, Judith, Hartford, Atheneum, 1971. Paperback, 20 pages, illustrated by Erik Blegvad.

Jasper Enters the Hospital, 16½ mins., The Day of Jasper's Operation, 13½ mins., Wellness: It's Not Magic, 15 mins., Video Cassettes‐ 16 mm. Available from: Kids Corner, 2027 North Tejon Street, Colorado Springs, Colorado 80907, (303) 475–2499.

First Do No Harm, produced by Pierce Atkins Corporation, 45 mins., S400 (purchase), S45 (daily rental). Distributed by Children's Hospital National Medical Center, 111 Michigan Avenue, N.W., Washington, D.C. 20010.

Pediatric Diagnostic Procedures With Guidelines for Preparing Children for Clinical Tests, Droske, Susan C. and Francis, Sally A. Toronto, John Wiley and Sons Inc., 1981.

The Children's Medical Series ‐ a series of eight videotapes with Susan Linn and her puppets.  相似文献   
9.
Vaping of synthetic cannabinoids via e‐cigarettes is growing in popularity. In the present study, we tentatively identified 12 by‐products found in a pure sample of the synthetic cannabinoid Cumyl‐5F‐PINACA (1‐(5‐fluoropentyl)‐N‐(2‐phenylpropan‐2‐yl)‐1H‐indazole‐3‐carboxamide), a prevalent new psychoactive substance (NPS) in e‐liquids, via high‐resolution mass spectrometry fragmentation experiments (HRMS/MS). Furthermore, we developed a procedure to reproducibly extract this synthetic cannabinoid and related by‐products from an e‐liquid matrix via chloroform and water. The extracts were submitted to flash chromatography (F‐LC) to isolate the by‐products from the main component. The chromatographic impurity signature was subsequently assessed by ultra‐high‐performance liquid chromatography coupled to mass spectrometry (UHPLC–MS) and evaluated by automated integration. The complete sample preparation sequence (F‐LC + UHPLC–MS) was validated by comparing the semi‐quantitative signal integrals of the chromatographic impurity signatures of five self‐made e‐liquids with varying concentrations of Cumyl‐5F‐PINACA [0.1, 0.2, 0.5, 0.7 and 1.0% (w/w)], giving an average relative standard deviation of 6.2% for triplicate measurements of preparations of the same concentration and 10.5% between the measurements of the five preparations with different concentrations. Lastly, the chromatographic signatures of 14 e‐liquid samples containing Cumyl‐5F‐PINACA from police seizures and Internet test purchases were evaluated via hierarchical cluster analysis for potential links. For the e‐liquid samples originating from test purchases, it was found that the date of purchase, the identity of the online shop, and the brand name are the critical factors for clustering of samples.  相似文献   
10.
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