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   36061篇
  免费   2676篇
  国内免费   312篇
耳鼻咽喉   552篇
儿科学   518篇
妇产科学   301篇
基础医学   2731篇
口腔科学   473篇
临床医学   1585篇
内科学   2172篇
皮肤病学   445篇
神经病学   2154篇
特种医学   757篇
外国民族医学   1篇
外科学   1810篇
综合类   1115篇
现状与发展   4篇
一般理论   1篇
预防医学   577篇
眼科学   22111篇
药学   968篇
  2篇
中国医学   52篇
肿瘤学   720篇
  2023年   1263篇
  2022年   2566篇
  2021年   2857篇
  2020年   2294篇
  2019年   1762篇
  2018年   2136篇
  2017年   1784篇
  2016年   1754篇
  2015年   1972篇
  2014年   3250篇
  2013年   3399篇
  2012年   1464篇
  2011年   1029篇
  2010年   1943篇
  2009年   1510篇
  2008年   681篇
  2007年   734篇
  2006年   536篇
  2005年   422篇
  2004年   312篇
  2003年   344篇
  2002年   339篇
  2001年   394篇
  2000年   271篇
  1999年   425篇
  1998年   261篇
  1997年   294篇
  1996年   291篇
  1995年   281篇
  1994年   157篇
  1993年   139篇
  1992年   91篇
  1991年   87篇
  1990年   60篇
  1989年   72篇
  1988年   77篇
  1987年   48篇
  1985年   101篇
  1984年   196篇
  1983年   253篇
  1982年   182篇
  1981年   179篇
  1980年   140篇
  1979年   147篇
  1978年   138篇
  1977年   42篇
  1976年   75篇
  1975年   73篇
  1974年   65篇
  1973年   51篇
排序方式: 共有10000条查询结果,搜索用时 901 毫秒
71.
72.
73.
《The ocular surface》2020,18(4):926-935
PurposeTo visualize and quantify vascular networks in individuals with ocular surface squamous neoplasia (OSSN) through optical coherence tomography angiography (OCTA).MethodCross-sectional study of OSSN patients. Vascular networks were measured by OCTA in the epithelium and sub-epithelial space in the tumors, adjacent tissue, and in the contralateral eye. Vessel area density (VAD, percent of blood vessels within 2.14 mm2), was calculated for each location. Total tumor density (TTD, percent of blood vessels within the entire tumor) was calculated. VAD was assessed separately for corneal and conjunctival locations and compared.ResultsFifteen patients with OSSN were included. The mean age was 61 ± 12 years and the majority were male (80%). The mean tumor area, volume, depth, and TTD were 28.0 ± 9.0 mm2 (range, 10.9–39.7), 9.1 ± 4.1 mm3 (range, 3.4–18.8), 334 ± 125 μm (range, 177–571), and 33.2% ± 11.0% (range, 18.7–58.8), respectively. The VAD was highest within the tumor (28.9% ± 8.7%) followed by the adjacent sub-epithelial tissue and the tissue underneath the conjunctival component of tumor. These densities were higher than the VAD in the tissues of the non-involved eye (all P < 0.05). The VAD within conjunctival component of tumor was significantly higher than those with corneal component (29.8% ± 9.5% vs. 21.1% ± 5.5%, p = 0.006). The VAD under conjunctival tumor was also significantly higher than under corneal component (24.1% ± 7.8% vs. 17.0% ± 6.1%, p = 0.024).ConclusionsOCTA imaging allowed for visualization and quantification of vessel structure and density within, under, and surrounding OSSN.  相似文献   
74.
Graefe's Archive for Clinical and Experimental Ophthalmology - To estimate the impact of delayed care during the coronavirus disease 2019 (COVID-19) pandemic on the outcomes of patients with...  相似文献   
75.
76.
77.
78.
79.
Specificity, antibody isotype distribution and levels, of natural autoantibodies (NAAb) may be potential informative parameters for immune mediated natural disease resistance, immune modulation, and maintenance of physiological homeostasis. In a previous study we detected IgM and IgG antibodies to liver antigens in plasma from 1 year old chickens. Auto-immune profiles directed towards liver antigens differed between chicken lines divergently selected for specific antibody responses to sheep red blood cells. In the present study we measured the presence and typed levels and antibody isotypes (IgG and IgM) of NAAb binding the ‘auto-antigen’ complex chicken liver cell lysate (CLL) in plasma samples obtained from chickens at 5 weeks and at 1-year of age, respectively, by quantitative western blotting.Extensive staining patterns of plasma antibodies binding CLL were found for both isotypes and at both ages in all birds. At both ages, IgM and IgG bound similar numbers of CLL antigens, which remained almost constant for IgM, whereas the number of IgG stained bands in time was enhanced. Significant differences of binding patterns of NAAb (stained antigen fragments of CLL and staining intensity) were detected between the three different chicken lines at both ages and between both ages, and lines could be clustered on the basis of their auto-antibody profile. The present results indicate that analysis of the plasma NAAb repertoire of poultry like in mammals could provide a way of distinguishing differences of immune competence (as reflected by the selection criterion of antibody responses) between individuals and lines, and could provide tools to select individual birds for health and other traits. The age-dependency of the auto-immune profile suggest that such profiles may also reflect immune maturation, which should be taken into account when relating an auto-immune profile with other traits.  相似文献   
80.
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