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   124237篇
  免费   8453篇
  国内免费   450篇
耳鼻咽喉   1633篇
儿科学   3293篇
妇产科学   2070篇
基础医学   15971篇
口腔科学   2368篇
临床医学   12530篇
内科学   26296篇
皮肤病学   1914篇
神经病学   11954篇
特种医学   4268篇
外国民族医学   4篇
外科学   18004篇
综合类   1882篇
现状与发展   1篇
一般理论   167篇
预防医学   11088篇
眼科学   2908篇
药学   8698篇
  2篇
中国医学   172篇
肿瘤学   7917篇
  2023年   473篇
  2022年   703篇
  2021年   2072篇
  2020年   1230篇
  2019年   2018篇
  2018年   2322篇
  2017年   1787篇
  2016年   1961篇
  2015年   2413篇
  2014年   3441篇
  2013年   5332篇
  2012年   7759篇
  2011年   8287篇
  2010年   4692篇
  2009年   4511篇
  2008年   7968篇
  2007年   8515篇
  2006年   8354篇
  2005年   8638篇
  2004年   8169篇
  2003年   8000篇
  2002年   7572篇
  2001年   1182篇
  2000年   927篇
  1999年   1231篇
  1998年   1704篇
  1997年   1426篇
  1996年   1161篇
  1995年   1147篇
  1994年   942篇
  1993年   960篇
  1992年   756篇
  1991年   706篇
  1990年   671篇
  1989年   625篇
  1988年   575篇
  1987年   543篇
  1986年   545篇
  1985年   662篇
  1984年   831篇
  1983年   830篇
  1982年   1162篇
  1981年   1052篇
  1980年   951篇
  1979年   464篇
  1978年   575篇
  1977年   547篇
  1976年   449篇
  1975年   408篇
  1974年   365篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
81.
(1) The estrous cycle in the rat may be used to study recurrent changes in motor behaviors and motivation which are strongly related to cyclic hormonal and CNS changes. (2) The peak in motivated behaviors occurs during a sharply defined period on the night between proestrus and estrus and is evident in facilitated wheel-running, lordosis, and intracranial self-stimulation. (3) Behaviors without a clearly motivated character do not show an estrous cyclicity. (4) The estrous cyclic variation in intracranial self-stimulation was observed at a specific locus — the pars campacta of the substantia nigra. (5) A neurochemical link between sexually motivated behavior, wheel running and intracranial self-stimulation is suggested. This link is in part dopaminergic but is probably also activated by many other systems.  相似文献   
82.
Summary An infant girl is described who had cor triatriatum and partial anomalous pulmonary venous connection of the left pulmonary veins to the coronary sinus, the first report of this combination of lesions. The infant also had a Dandy-Walker malformation and multiple facial and intrathoracic hemangiomas. The cardiac diagnosis was made by two-dimensional echocardiography. Cardiac catheterization and angiography confirmed the findings and also demonstrated a persistent left superior vena cava draining to the coronary sinus. The infant underwent successful surgical repair. Partial anomalous pulmonary venous connection and left superior vena cava not infrequently are associated with cor triatriatum. Although two-dimensional echocardiography is sensitive for the detection of cor triatriatum, preoperative cardiac catheterization is necessary to identify unequivocally systemic and pulmonary venous connections.  相似文献   
83.
BACKGROUND: Endothelin, a peptide with strong vasoconstrictive and mitogenic properties, has been found to increase after cardiac transplantation. We therefore assessed the association between its precursor peptide, big endothelin-1, and intimal hyperplasia and coronary flow reserve after heart transplantation. METHODS: Thirty-five patients without hemodynamically significant coronary artery disease after heart transplantation were investigated: Average peak flow velocity in the left anterior descending artery (LAD) was assessed by intracoronary Doppler at baseline as well as after injection of adenosine; coronary flow reserve was calculated as a ratio of both and was corrected for patient age and baseline average peak flow velocity. Lumen, intima + media and total vessel area were measured by intracoronary ultrasound. The plasma concentration of big endothelin-1 in venous blood was determined by radioimmunoassay. RESULTS: Patients with elevated big endothelin-1 levels (>2 fmol/ml) tended to have a decreased corrected coronary flow reserve (2.60 +/- 0.9 vs 3.21 +/- 1.0, p = 0.078). They also had a significantly larger intima + media area (5.82 +/- 2.9 vs 2.37 +/- 2.9 mm(2), p = 0.004) and total vessel area (18.36 +/- 5.8 vs 12.81 +/- 4.8 mm(2), p = 0.012) than those with normal plasma concentrations. CONCLUSIONS: Our study suggests an association between elevated big endothelin-1 plasma levels and the development of intimal hyperplasia and reduction of coronary flow reserve after cardiac transplantation.  相似文献   
84.
85.
Patients at Boston's Children's Hospital diagnosed as having cerebral palsy were filmed walking. These films were digitized and translated into measurements associated with leg motion. In this paper we use the gait measurements of 128 such patients to illustrate that the kth nearest neighbour clustering procedure results in a gait typology for patients with cerebral palsy. The procedure identifies four subpopulations from the sample data; the membership of a patient within this typology is mostly determined by the patient's motor control. The developed typology differs from the present diagnostic system which classifies a cerebral palsy patient as either quadriplegic, diaplegic or hemiplegic.  相似文献   
86.
A 35-year-old man discovered a 1-cm nodule at the upper pole of the left testicle after blunt focal trauma. While the pain, tenderness, and location suggested hematoma or appendiceal torsion, the demonstration by ultrasound of the size, cystic nature, and extraparenchymal location was consistent with the rarely documented cyst of the tunica albuginea.  相似文献   
87.
88.
89.
90.
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