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   7899篇
  免费   480篇
  国内免费   52篇
耳鼻咽喉   68篇
儿科学   206篇
妇产科学   108篇
基础医学   1163篇
口腔科学   135篇
临床医学   582篇
内科学   1714篇
皮肤病学   435篇
神经病学   541篇
特种医学   405篇
外科学   1203篇
综合类   163篇
一般理论   4篇
预防医学   389篇
眼科学   273篇
药学   388篇
中国医学   28篇
肿瘤学   626篇
  2023年   62篇
  2022年   114篇
  2021年   205篇
  2020年   139篇
  2019年   177篇
  2018年   198篇
  2017年   167篇
  2016年   218篇
  2015年   240篇
  2014年   335篇
  2013年   318篇
  2012年   561篇
  2011年   520篇
  2010年   300篇
  2009年   278篇
  2008年   392篇
  2007年   379篇
  2006年   341篇
  2005年   393篇
  2004年   337篇
  2003年   277篇
  2002年   305篇
  2001年   246篇
  2000年   230篇
  1999年   192篇
  1998年   93篇
  1997年   78篇
  1996年   85篇
  1995年   75篇
  1994年   67篇
  1993年   41篇
  1992年   86篇
  1991年   95篇
  1990年   81篇
  1989年   109篇
  1988年   119篇
  1987年   91篇
  1986年   70篇
  1985年   67篇
  1984年   48篇
  1983年   43篇
  1982年   18篇
  1981年   19篇
  1980年   18篇
  1979年   32篇
  1978年   19篇
  1977年   23篇
  1976年   13篇
  1975年   12篇
  1974年   15篇
排序方式: 共有8431条查询结果,搜索用时 0 毫秒
21.
22.
A 4 month-old boy who had double-inlet left ventricle, severe subaortic stenosis, hypoplastic ascending aorta and coarctation of the aorta revealed severe respiratory failure. An urgent Norwood operation was done. The procedure consisted of enlargement of the ascending aorta and main pulmonary artery and a systemic-pulmonary shunt using 5 mm PTFE tube. Postoperative course was uneventful.  相似文献   
23.
This study describes the effects of Norplant on haemostatic function after 5 years of use in 97 women. There was a decrease in vitamin-K dependent Factors II, V, VII and reduction in fibrinolytic activity at 2 and 4 years of use. Increased platelet numbers and accelerated platelet aggregation were found throughout the 5 years of Norplant use, whilst raised alpha 2-Macroglobulin (a2-M) and antithrombin III (ATIII) antigen level were observed for up to 4 years of use. Prolonged Norplant use does not appear to activate the coagulation system and does not enhance a state of hypercoagulation.  相似文献   
24.
Recently, metastasis to N3 lymph nodes group was regarded as distant metastasis by the new TNM staging system due to poor overall survival. However, the 5-year overall survival rate of patients with metastasis to N3 groups was 34.5% after curative surgery. Moreover, in patients with metastasis to lymph node subgroups of #12, #13, #14, the overall 5-year survival rate increased upto 47.2% after curative resection and adjuvant chemotherapy. This was similar to that of the patients with metastasis to N1 and N2 lymph nodes groups. But in these highly tumor burden states, no survival benefit was found with the addition of immunotherapy to chemotherapy as we achieved in stage II and III. Therefore, we suggest that, at least, metastasis to #12, #13, #14 lymph nodes subgroups should not be categorized as a distant metastasis. And in these situations, active curative radical surgery with extended lymphadenectomy and adjuvant chemotherapy are recommended.  相似文献   
25.
26.
Signals generated from muscles other than the muscle(s) of interest (cross talk) can confound the interpretation of surface electromyograms (EMGs). In this study, the amount of cross talk in surface EMGs of human hamstring muscles was estimated using a protocol in which the quadriceps femoris was electrically stimulated via the femoral nerve. EMGs were recorded from the vastus lateralis and the medial and lateral hamstring muscle groups. The amplitude of the EMG response of the vastus lateralis to electrical stimulation was adjusted to match that of its maximum voluntary effort (MVE) under isometric conditions. Subsequent power density spectrum analysis showed that the median frequencies of the signals generated by electrical stimulation and MVE were not significantly different. In conventional bipolar recordings, cross talk in lateral hamstring EMGs averaged 17.1% MVE and in medial hamstring EMGs 11.3% MVE (average-rectified values). The double differential technique significantly reduced cross talk to 7.6% MVE for the lateral hamstrings, and to 4.2% MVE for the medial hamstrings. The double differential technique appears to be more selective than the bipolar technique when recording EMGs from muscles with highly active neighbors and thus should be used in such situations. Software simulations of the double differential technique also appear to be more selective than the bipolar technique and may be used when the number of amplifiers available is limited.  相似文献   
27.
28.
Reiman  TH; Heiken  JP; Totty  WG; Lee  JK 《Radiology》1988,169(2):564-566
Limited-field-of-view radio-frequency receiver antennas provide improved near-field sensitivity for magnetic resonance imaging by decreasing the antenna volume. The Helmholtz-type surface coil, consisting of two flat rings, is an organ-encompassing antenna that takes advantage of this principle to yield an improved signal-to-noise ratio (S/N). The coil was tested in a group of 50 patients and 16 healthy volunteers. Images obtained with the Helmholtz coil demonstrated quantitatively superior S/N of 2.2-fold or greater than that of comparison body coil images, as well as qualitatively superior anatomic resolution.  相似文献   
29.
Surgical results of total anomalous pulmonary venous connection (TAPVC) has been improved in recent years, however, late development of pulmonary venous obstruction was our concern in its total correction in early infancy. In the cardiac type of TAPVC, in which the pulmonary veins were connected to the right lateral wall, prosthetic patch is conventionally used in diversion of pulmonary venous flow into left atrium. It seemed favorable to repair this subset without using prosthesis. A 3-month-old female with TAPVCIIb according to Darling's classification underwent total correction on September 22th, 1988. Two pedicled flaps were developed using the right atrial wall and the atrial septum to create a pulmonary venous channel to divert arterial blood into left atrium and absorbable sutures were used throughout. Right atrium was entered through a vertical incision in its body and all the pulmonary veins were found in a recess in the lateral wall of the right atrium. Atrial septal defect in the cranial aspect of the fossa ovalis was enlarged by cutting the primum tissue along the right limbus and its caudal margin so as to form a pedicled flap attached to the left limbic tissue. Then the flap was sutured along the limbus to create a roof of the fossa ovalis. The second flap was made in the middle of the lateral atrial wall and was used to create a tunnel from the recess to the atrial septal defect. The defect in the right atrial wall was closed directly and no prosthetic patch was used. Postoperative course was uneventful and echocardiogram showed wide pulmonary venous channel draining into the left atrium.  相似文献   
30.
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