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:      
  示例: 沙坡头地区,人工植被区,变化  检索词用空格隔开表示必须包含全部检索词,用“,”隔开表示只需满足任一检索词即可!
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   32029篇
  免费   767篇
  国内免费   45篇
耳鼻咽喉   396篇
儿科学   2235篇
妇产科学   676篇
基础医学   3446篇
口腔科学   560篇
临床医学   1851篇
内科学   5939篇
皮肤病学   1159篇
神经病学   1575篇
特种医学   1102篇
外科学   4762篇
综合类   1015篇
一般理论   10篇
预防医学   1486篇
眼科学   1599篇
药学   2594篇
  3篇
中国医学   170篇
肿瘤学   2263篇
  2024年   178篇
  2023年   201篇
  2022年   490篇
  2021年   934篇
  2020年   533篇
  2019年   649篇
  2018年   827篇
  2017年   556篇
  2016年   823篇
  2015年   761篇
  2014年   1161篇
  2013年   1410篇
  2012年   1994篇
  2011年   2102篇
  2010年   1134篇
  2009年   933篇
  2008年   1569篇
  2007年   1671篇
  2006年   1456篇
  2005年   1355篇
  2004年   1242篇
  2003年   1099篇
  2002年   948篇
  2001年   757篇
  2000年   713篇
  1999年   624篇
  1998年   269篇
  1997年   206篇
  1996年   163篇
  1995年   154篇
  1994年   131篇
  1993年   148篇
  1992年   360篇
  1991年   395篇
  1990年   353篇
  1989年   365篇
  1988年   312篇
  1987年   282篇
  1986年   269篇
  1985年   284篇
  1984年   220篇
  1983年   182篇
  1979年   241篇
  1978年   158篇
  1977年   148篇
  1976年   135篇
  1975年   163篇
  1974年   154篇
  1973年   176篇
  1972年   138篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
Yersinia enterocolitica is an enteric bacterium and infections by this organism are mostly foodborne. It has been implicated to cause enterocolitis, terminal ilitis. diarrhoea, mesenteric lymphadenitis and arthritis in man. Due to paucity of information regarding histopathological and specially ultrastructural alterations in tissues affected, this study was planned with mice as the experimental model. Nine pathogenic Y.enterocoliticaisolates were used to infect 80 albino mice by oral and intraperitoneal route. Pathological alterations were studied by light and electron microscopy. Histopathological examination of intestines showed severe edema, purulent enteritis, goblet cell hyperplasia infiltration of mononuclear cells, thickening of mucosa and necrosis of the tips of villi. Liver showed congestion, hepatocellular degeneration and necrosis, atrophy of hepatocytes and microabcesses. The lungs revealed congestion, edema, haemorrhage and purulent ronchopneumonia, while kidneys showed mild necrotic changes and bacterial emboli in glomeruli. Ultrastructural changes were indicative of mitochondrial degeneration and their loss in kidneys, membranous degeneration with formation of myelin figures in lungs and disorganization, disruption and bleb formation of microvilli in intestines. Y.enterocolitica caused significant histopathological and ultrastructural alterations in experimentally infected mice. Variation in pathogenicity of different strains of Y.enterocolitica was also observed.  相似文献   
72.
73.
The polymeric immunoglobulin receptor (pIgR) has been proposed as a therapeutic target, but its potential depends on the efficiency of uptake and trafficking of the receptor ligand. Mouse monoclonal antibodies (Mabs) directed against pIgR, selected for strong binding to secretory component (SC) and secretory IgA (sIgA), were tested in a transcytosis assay in 16HBEo--cells (human bronchial epithelial cell line) transfected with human pIgR. Intracellular trafficking was followed by confocal microscopy. Mabs fell into two classes. For two Mabs, transcytosis from basolateral to apical surface is rapid, unidirectional, and little Mab is retained in the cell. For three Mabs, basolateral to apical transcytosis occurs to a significantly lesser extent, reverse transcytosis is permitted, and some of the Mab is retained in the perinuclear region even after 24 h. When tested for their ability to recognize and immunoprecipitate pIgR with systematic truncations and deletions of the five immunoglobulin (Ig)-like domains, all Mabs bound to the fifth Ig-like domain, but three of them also bound to the C-terminal region of pIgR near the plasma membrane. Different binding sites probably account for the different trafficking of these Mabs and may predict differential therapeutic utility.  相似文献   
74.
Case records of the patients with major affective disorders (ICD-10 criteria), seen over a 5 year period in a busy clinic in North India were examined for Seasonal Affective Disorder (SAD) as per DSM-III-R criteria. In addition, seasonality of episodes of all affective disorders was also studied. Around 5.67% of the cases (n=44) retrospectively met the DSM-III-R criteria of SAD and predominant pattern was that of summer depression (n=18). There was also a consistent pattern of seasonal mania either in conjunction with seasonal depression (n=18) or in form of seasonal recurrent mania (n=11). None of the cases of depression showed any atypical vegetative features. In cases not meeting criteria for SAD (n=731), there was a trend for peaks for depressive episodes in winter followed by a smaller peak in summer months while manic episodes had peaks towards rainy and winter months. As compared to seasonal patterns of affective disorders in temperate zones, there was a general trend for opposite patterns of seasonality in SAD as well as in non-SAD. The findings are discussed in context of the climatic conditions of North India.  相似文献   
75.
76.
77.
78.
There is evidence that the faulty cognitions underlying an individual's playing behavior maintains and supports their gambling behavior. Sixty undergraduate students completed the South Oaks Gambling Screen (SOGS), a measure to assess pathological gambling, and a questionnaire ascertaining the type and frequency of their gambling activities. Sixteen Loto 6/49 tickets were presented to participants and ranked according to their perceived likelihood of being the winning ticket. The numbers on the tickets were categorized as: long sequences (e.g., 1-2-3-4-5-6), patterns and series in a pseudo-psychological order (e.g., 16-21-26-31-36-41), unbalanced (e.g., six numbers from 1-24 or 25-49), and those appearing to be random (e.g., 11-14-20-29-37-43). Verbal protocols of ticket selections were ranked into eight heuristics. Results revealed that for the entire sample the greatest percentage of tickets chosen for the first four selections were "random" tickets. Further, the most commonly cited reason for selecting and changing a lottery ticket was perceived randomness. The results are discussed with reference to the cognitions used when purchasing lottery tickets.  相似文献   
79.
A case report of the hornification of the nose is presented. It was present since birth, which increased with the advancing age. There were dark pigmented spots all over the body and both the conjunctiva:. Histopathology revealed the nose mass to be a horn like structure and the skin biopsy revealed it to be xeroderma. No case sofar in the literature is available of the hornification of the nose.  相似文献   
80.
Verma KS  Jain AK  Nagar A  Gupta SR 《Planta medica》1986,52(4):315-317
Macrocarposide has been isolated for the first time as a natural product from the heartwood of PTEROCARPUS MACROCARPUS along with some known compounds. Based on its spectral and chemical evidence, it has been assigned the structure dalbergioidin-6- C-glucoside ( 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