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   715922篇
  免费   49376篇
  国内免费   1357篇
耳鼻咽喉   9238篇
儿科学   23420篇
妇产科学   17753篇
基础医学   111767篇
口腔科学   20383篇
临床医学   64489篇
内科学   136682篇
皮肤病学   16348篇
神经病学   50154篇
特种医学   26317篇
外国民族医学   76篇
外科学   106103篇
综合类   14875篇
现状与发展   2篇
一般理论   160篇
预防医学   51738篇
眼科学   16513篇
药学   54563篇
  3篇
中国医学   2364篇
肿瘤学   43707篇
  2021年   5633篇
  2018年   8065篇
  2017年   6253篇
  2016年   7009篇
  2015年   7717篇
  2014年   10472篇
  2013年   15644篇
  2012年   20981篇
  2011年   22012篇
  2010年   12974篇
  2009年   12177篇
  2008年   20436篇
  2007年   21941篇
  2006年   22375篇
  2005年   20909篇
  2004年   20433篇
  2003年   19391篇
  2002年   18936篇
  2001年   36615篇
  2000年   37208篇
  1999年   30710篇
  1998年   8013篇
  1997年   6772篇
  1996年   7062篇
  1995年   6691篇
  1994年   6174篇
  1993年   5678篇
  1992年   23199篇
  1991年   23157篇
  1990年   22520篇
  1989年   22285篇
  1988年   20242篇
  1987年   19609篇
  1986年   18642篇
  1985年   17488篇
  1984年   12820篇
  1983年   10813篇
  1982年   5968篇
  1979年   11619篇
  1978年   8178篇
  1977年   6880篇
  1976年   6642篇
  1975年   7322篇
  1974年   8544篇
  1973年   8193篇
  1972年   7701篇
  1971年   7170篇
  1970年   6917篇
  1969年   6344篇
  1968年   5820篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
41.
This study was performed to evaluate the surgical strategy in patients with calvarial tumours, in order to design and modify a robot-assisted trepanation system. A total of 75 patients underwent craniectomy for the treatment of calvarial tumours during the 10-year period from 1993 to 2002. The patients' complaints, the size, location and histology of the tumour, and the various cranioplasty techniques used were analysed retrospectively. In a second procedure several craniectomies at typical locations according to the study's results were performed in a laboratory setting using a hexapod robotic tool, constructed at the Helmholtz-Institute, RWTH Aachen University, and plastic model heads. The workflow was documented and the reproducibility and the accuracy of the procedure were registered. A total of 83 surgical procedures were performed on 75 patients. The majority (87 %) of lesions treated surgically were located in the frontal, temporal and anterior parts of the parietal region. Histological examination revealed benign lesions in 66 % of the patients and dural involvement in 46 %. According to these results craniectomies were performed using the robotic system. Mean positioning accuracy of the robotic system while milling was 0.24 mm, with a standard deviation of 0.04 mm, and maximum error under 1 mm. Craniectomies leaving a 1-mm layer of the tabula interna intact to ensure a healthy dura were performed in several regions successfully. The majority of calvarial tumours, requiring surgical treatment in our patients, were located in cosmetically relevant areas in which drilling can be carried out with the robotic trepanation system. Consequently, the surgical approach had to be planned carefully in order to achieve a good cosmetic outcome.  相似文献   
42.
For many parents stopping life-sustaining medical treatment on their dying infant is psychologically impossible. Dostoevsky's insights into human behavior, particularly the fact that individuals do not want the anxiety and guilt associated with responsibility for making difficult decisions, might change the way physicians approach parents for permission to withdraw life-prolonging medical interventions on dying infants.  相似文献   
43.
A series of 1-alkyl-3,4-dihydroisoquinolines and the related 4-alkyl-1,2-dihydro-benzo[f]isoquinolines was synthesized using reactions of dialkylbenzylcarbinols and their naphthyl analogs with alkylcyanides. Experiments showed that 1-alkyl-6,7-dimethoxy-3,4-dihydroisoquinolines typically produce a hypotensive action, while the benzo-annelated structures usually exhibit a hypertensive effects. The most active compound decreases the arterial pressure in cats by 52 Torr and the effect lasts for about 4 hours. __________ Translated from Khimiko-Farmatsevticheskii Zhurnal, Vol. 40, No. 3, pp. 15–17, March, 2006.  相似文献   
44.
45.
46.
47.
OBJECTIVES: To reveal the frequency and the clinical characteristics of dystrophic calcification that occurs in children with juvenile dermatomyositis, multi-center analysis was constructed. METHOD: Fifty children with JDM were enrolled, and 14 of them (28.0%) were complicated with calcinosis. Clinical symptoms and laboratory tests at onset, initial therapy and disease course were compared in children with and without calcinosis. RESULTS: The mean age of the onset of calcinosis was 4.78 +/- 3.33 years, and it was younger than those of children without calcinosis (8.66 +/- 3.85 years) (P = 0.0017). No differences of clinical manifestation except Gower's sign were observed. The frequency of positive anti-nuclear antibody was 7.1% in children with calcinosis and 52.9% without calcinosis (P = 0.0112). The initial therapy of methylprednisolon pulses gave no effects on prognosis of calcium deposition. The calcinosis appeared in 1.56 +/- 1.91 year after the onset of the disease. The various types of calcium deposition including large tumorous clumps, subcutaneous plaques or nodules, sheet-type calcification were deserved. They appeared over knee joints (64.3%), elbow joint (64.3%), and hip processes (50.0%). Calcinosis affecting the subcutaneous tissues frequently resulted in painful superficial ulceration of the overlying skin (42.9%), local infection (50.0%), and limitation of joint movement (14.3%). Although aluminum phosphate was effective in 2 children among 7, no other effective treatment was recommended. In 5 cases, surgical removal of tumorous clumps was operated. Thus, juvenile dermatomyositis is frequently complicated with calcinosis. This type of calcinosis was found to be unlikely to resolve completely, and resulted in severe disability in children.  相似文献   
48.
OBJECTIVE: To study the effect of high-frequency (100 Hz) repetitive conditioning electrical stimulation (CES, 10 min) on human somatosensory evoked potentials (SEPs) to evaluate if short-term cortical plasticity could be induced. METHODS: Painful electrical stimulations were applied to thumb (D1) and little finger (D5) fingertips, respectively. The 124-channel EEG was recorded from 10 healthy male volunteers. Peak stages around 34, 45, 212, 331 ms were analyzed with focal maximum amplitude (FA) and area magnitude (AM) of scalp field potential, topography, and equivalent current dipole source localisation, comparing before and after two-level CES (high- vs. low-level) applied to the He-Gu acupoint. RESULTS: After a high-level CES, the positive FA and AM of the current efflux showed a significant increase at the early phase 34 ms, and significantly decreased at 45 ms in D1 SEPs. The negative FA and AM of the current influx were significantly increased at late phase 350 ms of the D5 SEPs. Only 36 ms, the z-axis position of dipole was significantly changed from (x: -15.9 mm, y: 29.6 mm, z: 43.9 mm) to (x: -12.9 mm, y: 29.4mm, z: 51.5mm) for the D5 SEPs. CONCLUSIONS: The high-level CES significantly attenuated the subsequent cortical activation (45 ms peak for D1 stimulation). Both low- and high-level CES significantly enhanced the late activities (226, 350 ms) in D5 stimulation. This may be explained by pain sensation change at the level of subcortical cingulate cortex induced by the site-dependent post-effect of CES. SIGNIFICANCE: This study showed cortical plasticity induced by conditioning somatosensory stimulation.  相似文献   
49.
50.
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