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   1074823篇
  免费   71748篇
  国内免费   1366篇
耳鼻咽喉   15015篇
儿科学   34621篇
妇产科学   28623篇
基础医学   153401篇
口腔科学   29555篇
临床医学   94910篇
内科学   203643篇
皮肤病学   24391篇
神经病学   81453篇
特种医学   42964篇
外国民族医学   201篇
外科学   163096篇
综合类   21702篇
现状与发展   1篇
一般理论   263篇
预防医学   74601篇
眼科学   24535篇
药学   86106篇
  7篇
中国医学   2805篇
肿瘤学   66044篇
  2019年   7756篇
  2018年   11293篇
  2017年   8906篇
  2016年   10094篇
  2015年   11263篇
  2014年   15267篇
  2013年   22200篇
  2012年   30545篇
  2011年   32289篇
  2010年   18953篇
  2009年   17814篇
  2008年   29949篇
  2007年   32069篇
  2006年   32701篇
  2005年   31031篇
  2004年   29720篇
  2003年   28550篇
  2002年   27529篇
  2001年   60026篇
  2000年   61477篇
  1999年   50927篇
  1998年   12446篇
  1997年   11000篇
  1996年   11014篇
  1995年   10323篇
  1994年   9341篇
  1993年   8859篇
  1992年   37788篇
  1991年   36273篇
  1990年   35747篇
  1989年   34289篇
  1988年   30867篇
  1987年   29989篇
  1986年   28217篇
  1985年   26448篇
  1984年   19185篇
  1983年   16114篇
  1982年   8823篇
  1979年   17029篇
  1978年   11404篇
  1977年   10229篇
  1976年   8837篇
  1975年   10068篇
  1974年   11651篇
  1973年   11273篇
  1972年   10754篇
  1971年   10092篇
  1970年   9252篇
  1969年   8939篇
  1968年   7919篇
排序方式: 共有10000条查询结果,搜索用时 7 毫秒
941.
Simultaneous immunoelectron microscopic localization of human chorionic gonadotropin (HCG) and human placental lactogen (HPL) was examined on the same ultrathin section of human chorionic villi by means of the double labeling technique. Using specific rabbit antisera against HCG and HPL followed by goat anti-rabbit IgG-coated colloidal gold of different sizes (15 nm and 5 nm), immunoreactions of HCG were concentrated on middle-sized secretory granules of 200-300 nm and large dense bodies of 500-1000 nm, while those of HPL were exclusively located on small secretory granules of 80-180 nm. The present experiment provides direct evidence for our previous data that HCG and HPL seem to be stored in different granular components in the syncytiotrophoblast.  相似文献   
942.
The formation of lens alpha-neoprotein molecules which are built by the association of A and B subunit chains of alpha-crystallin but have a different quaternary structure than the native protein is a posttranslational process that progresses through the life span. Alpha-neoproteins occur regularly in all mature mammalian lenses tested. The mechanisms that have been identified for the formation of alpha neoproteins are imbalance in the biosynthesis of A- to B-chains, which leads to a ratio of less than 2A-chains to 1B-chain, and derivation of the chains after their initial association into native alpha-crystallin. In terms of quantity of neoproteins, no significant differences have been found between lenses with developing cataracts and normal control lenses of corresponding age. The possibility that there are structural differences between alpha-neoproteins in normal and cataractous lenses of the same age, as well as potential differences among alpha-neoproteins isolated from normal lenses of different ages, are presently under investigation.  相似文献   
943.
A new member, species C, of the Anopheles quadrimaculatus complex was recently found in collections from the northwest coast of Florida. This new species cannot be differentiated from the other 2 species with available taxonomic keys. Evidence for this taxon as a sibling species includes data on hybrid sterility and distorted sex ratios in the progeny of crosses to species A and B, chromosomal differences, and diagnostic allozymes.  相似文献   
944.
Progressive peripheral cone dysfunction   总被引:1,自引:0,他引:1  
A 22-year-old man had a three-year history of progressive day blindness, most notably peripherally, and denied difficulty with central vision or color vision. Visual function studies demonstrated a diffuse dysfunction of the photopic system and normal scotopic function. The central cone function, however, was essentially normal. Visual acuity was 20/20 in each eye, results on AO-HRR and Ishihara color plate testing were normal, color naming visual fields demonstrated color discrimination in the central 10 degrees, and foveal adaptation was normal.  相似文献   
945.
946.
947.
Intestinal thermophilic Campylobacter species produce stable patterns when subjected to bacterial restriction endonuclease DNA analysis (BRENDA); this technique is therefore of considerable value in epidemiological studies. BRENDA was used to examine thermophilic Campylobacter species from humans, wild and domestic animals. One hundred and ninety-four (61%) of 316 isolates of Campylobacter jejuni from humans had BRENDA patterns which could be matched to those of animal isolates. Poultry appear to be a major source of infection for C. jejuni in humans with nearly half (49.7%) of the human isolates giving patterns which were indistinguishable from those isolated from poultry. A total of 60 BRENDA types were identified from 316 human isolates and 11 of these had the same pattern as those isolated from poultry. One of the three Campylobacter coli BRENDA types recovered from poultry was indistinguishable from a human isolate type. Pigs appear to be only a minor source of C. coli infection for humans in New Zealand. Rats were found to be infected with strains of C. jejuni with BRENDA patterns indistinguishable from those infecting humans, poultry and a horse. None of the 102 isolates of Campylobacter species from wild birds gave BRENDA patterns similar to those of isolates from humans.  相似文献   
948.
On the basis of a series of 500 patients the authors describe the development of silicone oil surgery, the surgical technique, and present-day indications for it, as well as the results that can be achieved with this procedure. The postoperative problems (cataract, glaucoma, and keratopathy) are analyzed and guidelines presented for reducing the complication rate.  相似文献   
949.
950.
Ocular manifestations of childhood leukemia   总被引:1,自引:0,他引:1  
  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