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   687304篇
  免费   312438篇
  国内免费   60274篇
耳鼻咽喉   5865篇
儿科学   9740篇
妇产科学   6877篇
基础医学   136031篇
口腔科学   9722篇
临床医学   119919篇
内科学   151425篇
皮肤病学   9407篇
神经病学   41358篇
特种医学   24595篇
外国民族医学   260篇
外科学   81518篇
综合类   136516篇
现状与发展   102篇
一般理论   49篇
预防医学   73739篇
眼科学   27172篇
药学   103346篇
  620篇
中国医学   72053篇
肿瘤学   49702篇
  2024年   7641篇
  2023年   10562篇
  2022年   20183篇
  2021年   24649篇
  2020年   23439篇
  2019年   26288篇
  2018年   26457篇
  2017年   26837篇
  2016年   24414篇
  2015年   31292篇
  2014年   35629篇
  2013年   34077篇
  2012年   45466篇
  2011年   50778篇
  2010年   41471篇
  2009年   44882篇
  2008年   36837篇
  2007年   33683篇
  2006年   32018篇
  2005年   30659篇
  2004年   24798篇
  2003年   23473篇
  2002年   21186篇
  2001年   21320篇
  2000年   16398篇
  1999年   21196篇
  1998年   19298篇
  1997年   18887篇
  1996年   18740篇
  1995年   18645篇
  1994年   17806篇
  1993年   15444篇
  1992年   15161篇
  1991年   14137篇
  1990年   12870篇
  1989年   12442篇
  1988年   11695篇
  1987年   11021篇
  1986年   10329篇
  1985年   9165篇
  1984年   6918篇
  1983年   6826篇
  1982年   7752篇
  1981年   7274篇
  1980年   6901篇
  1979年   6780篇
  1978年   5889篇
  1977年   6168篇
  1976年   5774篇
  1975年   5511篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
61.
Wir berichten über den ersten Fall von polyzystischer lipomembran?ser Osteodysplasie oder “brain, bone and fat disease” in Deutschland. Die nach dem Erstbeschreibern auch als Morbus J?rvi-Hakola-Nasu bezeichnete Erkrankung ist bisher vor allem in Japan und in Finnland beschrieben worden. Einzelne F?lle wurden aus Schweden, Norwegen, Italien, Südafrika, Belgien und den USA berichtet. Im deutschsprachigen Raum ist bisher ein Fall aus ? ver?ffentlicht worden.  相似文献   
62.
63.
64.
65.
Galanin-like immunoreactivity has been visualized in nerve fibers in the islets of Langerhans, suggesting an involvement of galanin in the neural regulation of islet function. In this study, we investigated the effects of galanin on basal and stimulated insulin and glucagon secretion by infusing the peptide at three different dose rates in rats. We also studied the direct effect of galanin on insulin secretion from freshly isolated rat islets. At 320 pmol/kg/min, but not at 20 or 80 pmol/kg/min, galanin lowered basal plasma insulin levels. In contrast, basal plasma glucagon levels were lowered by galanin already at 20 and 80 pmol/kg/min. Furthermore, galanin inhibited both glucose- and arginine-induced insulin release at all three dose levels, whereas arginine-induced glucagon release was not affected by galanin. Glucose-stimulated insulin secretion from isolated rat islets was dose-dependently suppressed by galanin (10-6-10-8M). Therefore, it is concluded that galanin in rats inhibits insulin secretion, both in vivo and in vitro, and that at lower dose levels, the peptide also inhibits basal glucagon release.  相似文献   
66.
J S Li 《中华外科杂志》1989,27(10):629-33, 640
Serum aminogram changes were prospectively studied in 95 patients with enteric fistula and intraabdominal infection who was under total parenteral nutrition (TPN) therapy with Anfuming 14s. In patients with sepsis and starvation, the aminogram showed remarkably low total free amino acids before TPN therapy. In 81 survivors, free amino acids increased gradually to normal in 2 weeks after use of TPN and in 14 dead cases increased rapidly to a significantly higher peak at terminal stage. Both in survivors and nonsurvivors, phenylalanine level remained high during the study. In response to infection, proline was also elevated but to a lesser degree; the ratio of branched chain amino acid (BCAA) to aromatic amino acid (AAA) was lower than normal and the decrease of arginine was parallel to the severity of infection. We conclude that the ideal amino acids preparation for the starvated and septic patients should be high in BCAA and arginine but low in phenylalanine, administration of inappropriate exogenous amino acids in decompensated metabolic septic patients may bring about more harm than benefit, and in septic patients that the levels of serum phenylalanine and proline are elevated persistently along with the decrease of arginine level is a useful prognostic indication.  相似文献   
67.
1. Postmortem neurochemical investigations revealed interhemispheric asymmetry in the mediofrontal region of human brain. Significantly higher right hemisphere serotonin metabolite (5HIAA) content as well as increased maximal imipramine binding (IB) were found in the right hemisphere than in the left side.

2. IB did not show a gender difference in the mediofrontal area. However, women had higher IB in the right orbital frontal cortex than did men.

3. In vivo pharmaco-EEG results tend to support the postmortem neurochemical data. Intravenous chlorimipramine resulted in an asymmetric topographic distribution of the P300 auditory evoked potential, peak amplitudes were shifted to the right hemisphere.  相似文献   

68.
69.
70.
The neuroprotective effects of dizocilipine maleate (MK-801), a noncompetitive antagonist of the N-methyl-D-aspartate (NMDA) receptor/channel, were tested in the 4-vessel occlusion rat model of forebrain ischemia. Adult Wistar rats, treated intraperitoneally with MK-801 or saline using several different treatment paradigms were subjected to 5 (n = 208) or 15 (n = 62) min of severe, transient forebrain ischemia. In saline-treated animals, 15 min of ischemia (n = 13) produced extensive and consistent loss of pyramidal neurons in the CA1 zone of hippocampus. The degree and distribution of cell loss were not reduced by single dose preischemic administration of MK-801 at 1 (n = 7), 2.5 (n = 4), or 5 mg/kg (n = 8). In other animals subjected to 15 min of forebrain ischemia, multiple doses of MK-801 (5, 2.5, and 2.5 mg/kg) given immediately and at approximately 8 and 20 hr after cerebral reperfusion (n = 5) did not alter CA1 injury compared to saline-treated controls (n = 5). Five minutes of forebrain ischemia in saline-treated animals, (n = 82) resulted in significantly fewer (p less than 0.001) dead CA1 pyramidal cells and a greater variance compared to animals subjected to 15 min of ischemia. Power analysis of the preliminary saline-treated animals subjected to 5 min of ischemia (n = 22) indicated that 60 animals per group were necessary to detect a 15% difference between MK-801 and vehicle-treated groups. Multidose treatment with MK-801 (1 mg/kg) given 1 hr prior to 5 min of ischemia (n = 60) and again at approximately 8 and 16 hr after recirculation failed to attenuate hippocampal injury.(ABSTRACT TRUNCATED AT 250 WORDS)  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