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   30412篇
  免费   1498篇
  国内免费   191篇
耳鼻咽喉   427篇
儿科学   532篇
妇产科学   546篇
基础医学   3881篇
口腔科学   744篇
临床医学   2103篇
内科学   8237篇
皮肤病学   527篇
神经病学   2459篇
特种医学   957篇
外科学   4965篇
综合类   122篇
一般理论   2篇
预防医学   1152篇
眼科学   434篇
药学   1924篇
中国医学   46篇
肿瘤学   3043篇
  2022年   241篇
  2021年   521篇
  2020年   291篇
  2019年   359篇
  2018年   513篇
  2017年   414篇
  2016年   493篇
  2015年   523篇
  2014年   706篇
  2013年   899篇
  2012年   1435篇
  2011年   1559篇
  2010年   867篇
  2009年   794篇
  2008年   1443篇
  2007年   1583篇
  2006年   1535篇
  2005年   1459篇
  2004年   1492篇
  2003年   1475篇
  2002年   1501篇
  2001年   984篇
  2000年   982篇
  1999年   870篇
  1998年   407篇
  1997年   314篇
  1996年   295篇
  1995年   275篇
  1994年   236篇
  1993年   200篇
  1992年   642篇
  1991年   669篇
  1990年   571篇
  1989年   577篇
  1988年   556篇
  1987年   510篇
  1986年   448篇
  1985年   451篇
  1984年   335篇
  1983年   253篇
  1982年   120篇
  1979年   247篇
  1978年   139篇
  1977年   145篇
  1974年   133篇
  1973年   127篇
  1972年   144篇
  1971年   128篇
  1969年   138篇
  1967年   129篇
排序方式: 共有10000条查询结果,搜索用时 78 毫秒
51.
To determine the clinical significance of regional left ventricular asynergy in patients with impending myocardial infarction, we recorded two-dimensional echocardiograms (2DE) serially and performed coronary angiography immediately after the hospital admission in nine patients with initial impending infarction and their last anginal attacks were within 48 hours. Left ventricular asynergy on the first 2DE was observed in six of nine patients during symptom-free periods (Group A: LV asynergy group). Five of the six patients had significant coronary artery lesions (greater than or equal to 75% stenosis) in at least one major coronary artery. Intracoronary filling defects were detected in four of the five patients. Another three patients without asynergy (Group B) had significant fixed stenosis. Coronary artery spasm was observed in two patients during coronary angiography, but no patient had intracoronary filling defects. Intracoronary nitroglycerin (0.1-0.3 mg) reduced the severity of coronary artery narrowing in two patients. In addition, urokinase (240,000-480,000 IU) via the corresponding vessel (PTCR) in the remaining seven patients resulted in reduction in the severity of coronary artery stenosis in four patients, but not in the remaining three patients. Left ventricular wall movement in the asynergy group improved rapidly and no asynergy was observed by the seventh hospital day in five of the six patients. Successful PTCR treatment resulted in improvement of left ventricular wall movement. No asynergy was found in the non-asynergy group throughout their hospitalizations. These findings indicated that abnormal left ventricular wall movement is found in patients with impending myocardial infarction, even during symptom-free periods, but the wall movement gradually improves. The 2DE observations are useful for estimating the clinical status and for planning precise therapy for impending myocardial infarction.  相似文献   
52.
T Hijikata  H Saito  T Yohro 《The Prostate》1986,8(3):277-291
Gross anatomy and the light and electron microscopic characteristics of the musk shrew (Suncus murinus, Insectivora) prostate are described. The prostate is a pair of compound tubuloalveolar glands with one main excretory duct for each gland. Each gland is divided into ventral and dorsal lobes. The tubuloalveoli are larger in diameter and the secretory cells are lower in the ventral than in the dorsal lobes. Probable spontaneous release of secretory granules and accumulation of secretory material in secretory lumina are only observed in the ventral lobes. Secretory material is often crystallized in the secretory lumina. The epithelium of excretory ducts consists of mucous-type secretory cells and the boundary between this epithelium and the glandular epithelium is complex. The glandular epithelium consists of secretory and clear cells. This report illustrates that the structure of the prostate of musk shrew is unique among mammals.  相似文献   
53.
54.
55.
Endothelin, a 21-amino acid peptide produced by vascular endothelial cells, caused a sustained constriction of isolated large cerebral arteries of cats in a dose-dependent manner. The increased tone of the tissue did not return to the resting level after repeated washings. No vasodilator response was evoked by endothelin in the presence of an active tone. The contractile response of cerebral arteries was not inhibited by rubbing of the endothelium, cold storage denervation or indomethacin. In contrast, nicardipine or diltiazem antagonized the endothelin-induced contraction non-competitively. No contraction was evoked by endothelin in a Ca2+-free solution while the addition of Ca2+ ions in the presence of endothelin in a Ca2+-free solution caused a sustained contraction. Ca2+-induced contraction in the Ca2+-free solution containing endothelin was also inhibited by nicardipine. Therefore, endothelin causes a direct contraction of the smooth muscles of cat cerebral arteries, probably by activating the influx of Ca2+ ions through L-type Ca2+ channels of smooth muscles.  相似文献   
56.
It is well known that long-term infection with Clonorchis sinensis often causes bile duct cancer, usually. It occurs in the intrahepatic bile duct. We encountered a rare case of clonorchiasis complicated with duodenal papillary cancer. The patient was a woman from China. Although clonorchiasis is rarely found in Japan, the promotion of international exchange may increase the number of visitors from endemic areas. Thus we must pay sufficient attention to this disease. Also, we reported that the microplate ELISA technique was useful in the diagnosis of clonorchiasis with high accuracy in this case.  相似文献   
57.
Cholesteryl ester transfer protein (CETP) greatly affects the metabolism of all lipoprotein classes including low-density lipoprotein (LDL) and high-density lipoprotein (HDL), both known to constitute powerful risk factors for coronary artery disease (CAD). We now report the successful first cloning and characterization of single-chain antibody fragments specific for CETP. A recombinant phage display library was generated using spleen mRNA isolated from BALB/c mice that had been immunized with highly purified CETP. Screening of the library yielded two single-chain antibody fragments with high affinity for CETP, termed 1CL8 and 1CL10, displaying respective KD values of 4.36 x 10(-9) M and 4.64 x 10(-9) M as determined by affinity sensor technology. Amino acid sequence comparison indicated the complementarity-determining regions of the respective heavy chains to be responsible for CETP high affinity binding. Fragment 1CL8 was successfully employed in clinical chemical quantification systems that uncovered an association in humans between plasma CETP concentration and total body fat mass (r=0.50, p<0.002). Because of the demonstrated superb CETP capturing capacity, combined with high binding affinity to CETP, ready access and unlimited supply, 1CL8 and 1CL10 are expected to prove powerful tools for studies on the role of CETP in atherogenesis.  相似文献   
58.
Endoscopic submucosal dissection (ESD) for colorectal cancer is not widely accepted because of its technical difficulty and the risk of perforation. In addition, the risk of peritonitis cannot be completely eliminated even if a perforation is closed successfully. Reported here are two cases of early colon cancer in which the patients sustained iatrogenic perforations of the ascending colon during conventional endoscopic mucosal resection and of the sigmoid colon during ESD, respectively, requiring abdominal decompression with an 18 G Medicut needle. Both of these perforations were successfully treated by endoscopic clipping. In conclusion, conservative medical management may be possible in patients who have undergone successful closure of colonic perforations using endoscopic clipping. In order to perform immediate endoscopic closure, abdominal decompression has been useful to decrease patient discomfort and colonic lumen collapse. Now, CO2 insufflation is being used effectively for the prevention of pneumoperitoneum.  相似文献   
59.
BACKGROUND: An association between Brugada syndrome and neurally mediated syncope has been described. Although mutations in SCN5A have been identified in Brugada syndrome, the genetic link between Brugada syndrome and neurally mediated syncope has not been determined. OBJECTIVES: The purpose of the study was to clinically and genetically characterize a man with recurrent syncope that originally was diagnosed as neurally mediated syncope at age 8 years but subsequently manifested as Brugada syndrome at age 17 years. METHODS: The proband underwent clinical examination, which included head-up tilt test, sodium channel provocation test, and electrophysiologic study. Genetic screening of SCN5A was performed for the proband and his family members. The biophysical properties of a mutant SCN5A channel in a heterologous expression system were studied using whole-cell, patch clamp technique. RESULTS: The proband showed positive head-up tilt test, coved-type ST elevation recorded from the third intercostal space, and positive pilsicainide provocation test. Ventricular fibrillation was inducible at programmed electrical stimulation, consistent with characteristics of both Brugada syndrome and neurally mediated syncope. A novel nonsense SCN5A mutation (Q55X) was identified in the proband, his mother, and his asymptomatic brother. The heterologously expressed mutant channel was nonfunctional. CONCLUSION: We genetically determined an SCN5A mutation in a patient showing the combined phenotype of neurally mediated syncope and Brugada syndrome. Neurally mediated syncope and Brugada syndrome may share, at least in part, a common pathophysiologic mechanism.  相似文献   
60.
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