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   1873篇
  免费   91篇
  国内免费   10篇
耳鼻咽喉   16篇
儿科学   77篇
妇产科学   214篇
基础医学   234篇
口腔科学   18篇
临床医学   121篇
内科学   347篇
皮肤病学   18篇
神经病学   81篇
特种医学   69篇
外科学   280篇
综合类   43篇
一般理论   1篇
预防医学   71篇
眼科学   73篇
药学   91篇
中国医学   3篇
肿瘤学   217篇
  2022年   19篇
  2021年   23篇
  2020年   24篇
  2019年   40篇
  2018年   38篇
  2017年   38篇
  2016年   48篇
  2015年   60篇
  2014年   53篇
  2013年   74篇
  2012年   104篇
  2011年   101篇
  2010年   59篇
  2009年   55篇
  2008年   79篇
  2007年   78篇
  2006年   74篇
  2005年   75篇
  2004年   69篇
  2003年   48篇
  2002年   50篇
  2001年   53篇
  2000年   59篇
  1999年   71篇
  1998年   30篇
  1997年   30篇
  1996年   25篇
  1995年   10篇
  1994年   18篇
  1993年   33篇
  1992年   28篇
  1991年   38篇
  1990年   34篇
  1989年   40篇
  1988年   20篇
  1987年   18篇
  1986年   19篇
  1985年   24篇
  1982年   11篇
  1981年   13篇
  1979年   21篇
  1977年   9篇
  1974年   13篇
  1973年   12篇
  1972年   16篇
  1970年   9篇
  1969年   9篇
  1968年   9篇
  1967年   9篇
  1966年   11篇
排序方式: 共有1974条查询结果,搜索用时 0 毫秒
31.
Purpose:To describe and validate the eye health program protocol of Dongria tribal community, a particularly vulnerable tribal group (PVTG) in Rayagada district, Odisha, India.Methods:The program would consist of three segments. At people’s residences, trained community health workers (CHWs) will measure the vision and collect demographic data. In addition, vision technicians (VTs) will refract using a hand-held device and prescribe spectacles to people who improve to >6/12, N8. Others would be referred to the vision center (VC). At VC, the VT will perform a slit-lamp examination and re-refract. They would refer people with vision ≤6/12 to the secondary center (SC). At SC, referred people will receive a comprehensive eye examination and treatment. The ophthalmologist will assign the cause of blindness and visual impairment for people with visual acuity <6/12. The entire process was rehearsed in a pilot study.Results:The target population is approximately 10,000 people residing in 101 hutments on the hills of Rayagada district. The pilot study included 126 people. The mean age was 44 ± 18 years; 70% of the people were illiterate, and in this cohort, 97.6% (n = 123) had never worn spectacles. In the pilot study, 41% of the people had cataract, and 12% had pterygium. The agreements between optometrist versus VTs and between optometrist versus CHWs were good (k = ~0.8–1.0) in all eye conditions except for strabismus (k = ~0.56–0.65)Conclusion:The pilot study confirms the program modality, and when completed, it would help in the planning and resource allocation of Odisha PVTG eye care.  相似文献   
32.
33.
34.
35.
Beta defensins (BD) are cysteine rich, cationic antimicrobial peptides (AMP) produced mainly by epithelial and myeloid cells such as neutrophils. In birds, the neutrophil equivalent heterophils produce avian beta defensins (AvBD) of which AvBD2 is the major isoform. Heterophils recognize pathogens or their derived products through a series of pattern recognition receptors called toll-like receptors (TLR) leading to their antimicrobial activities. This work is the first report of TLR modulation of AvBD2 expression in chickens. To measure the effect of TLR activation on AvBD2 production, the heterophils were cultured with different TLR agonists for 6 h. Modulation of AvBD2 levels by TLR activation was measured using direct MALDI mass spectrometry without stable isotopic labeling or chromatographic separation. Chemical modification of the conditioned media was performed using reduction/alkylation with dithiothreitol/iodoacetamide to distinguish TLR treated AvBD2 (reduced/alkylated) from controls (non-reduced). Changes in corrected ion intensity ratios were assumed to reflect AvBD2 modulation in heterophils upon activation with different TLR agonists. In general, TLR agonists increased AvBD2 production with LPS showing the greatest induction and CpG-ODN showing little or no effect. These data show that the direct MALDI-MS coupled with reduction/alkylation may provide a rapid relative quantitative approach to the measurement of agonist-induced differential expression of AvBD2.  相似文献   
36.
37.
38.
39.
AIM: Magnetic resonance imaging (MRI) based colonography represents a new imaging tool which has mainly been investigated for polyp screening. To evaluate this approach for patients with inflammatory bowel disease (IBD), we compared MRI based colonography with conventional colonoscopy for assessing the presence and extent of colonic inflammation. PATIENTS AND METHODS: In 22 consecutive patients with suspected or known IBD, MRI colonography was performed immediately before conventional colonoscopy. After bowel cleansing, a T1 positive contrast agent was applied rectally. In addition to T2 weighted sequences, T1 weighted two dimensional and three dimensional Flash acquisitions as well as volume rendered virtual endoscopy were performed. All images were evaluated with regard to typical MRI features of inflammation. The results were compared with colonoscopy findings. RESULTS: Distension and image quality was assessed as good to fair in 97.4% of all colonic segments. Only four of 154 segments were considered non-diagnostic. With colonoscopy serving as the gold standard, the sensitivity for correctly identifying inflammation on a per segment analysis of the colon was 31.6% for Crohn's disease (CD) and 58.8% for ulcerative colitis (UC). In CD, in most cases mild inflammation was not diagnosed by MRI while in UC even severe inflammation was not always depicted by MRI. Virtual endoscopy did not add any relevant information. CONCLUSION: MRI based colonography is not suitable for adequately assessing the extent of colonic inflammation in patients with IBD. Only severe colonic inflammation in patients with CD can be sufficiently visualised.  相似文献   
40.
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