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   381188篇
  免费   23050篇
  国内免费   721篇
耳鼻咽喉   5230篇
儿科学   12463篇
妇产科学   12249篇
基础医学   58521篇
口腔科学   9407篇
临床医学   32219篇
内科学   73937篇
皮肤病学   7605篇
神经病学   28796篇
特种医学   15192篇
外国民族医学   96篇
外科学   58660篇
综合类   8348篇
现状与发展   1篇
一般理论   244篇
预防医学   26027篇
眼科学   8303篇
药学   26648篇
中国医学   974篇
肿瘤学   20039篇
  2021年   3778篇
  2019年   3691篇
  2018年   5329篇
  2017年   3850篇
  2016年   4494篇
  2015年   5200篇
  2014年   6774篇
  2013年   10606篇
  2012年   13783篇
  2011年   14250篇
  2010年   9318篇
  2009年   8402篇
  2008年   12963篇
  2007年   13986篇
  2006年   13784篇
  2005年   13289篇
  2004年   12894篇
  2003年   12046篇
  2002年   11672篇
  2001年   15564篇
  2000年   15899篇
  1999年   13540篇
  1998年   4120篇
  1997年   3723篇
  1996年   3441篇
  1995年   3349篇
  1994年   2981篇
  1993年   2933篇
  1992年   9802篇
  1991年   9882篇
  1990年   9627篇
  1989年   9401篇
  1988年   8436篇
  1987年   8178篇
  1986年   7779篇
  1985年   7498篇
  1984年   5463篇
  1983年   4795篇
  1982年   2956篇
  1979年   5052篇
  1978年   3608篇
  1977年   3095篇
  1976年   2804篇
  1975年   3215篇
  1974年   3763篇
  1973年   3710篇
  1972年   3464篇
  1971年   3248篇
  1970年   3091篇
  1969年   2810篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
92.
The purpose of this study was to provide, in a large number of patients, comprehensive Doppler echocardiographic assessment of normal St Jude Medical mitral valve prosthesis function using Doppler-derived hemodynamic variables, including the mitral valve prosthesis-to-left ventricular outflow tract time-velocity integral ratio and prosthesis performance index. The pressure half-time was less than 130 milliseconds in all patients, and all but one patient had either a peak early mitral diastolic velocity of 2 m/s or less or a mitral valve prosthesis-to-left ventricular outflow tract time-velocity integral ratio of less than 2.2. There was a significant (P < .001) negative correlation between the prosthesis performance index and prosthesis size. This negative correlation suggests that there is more efficient use of the in vitro geometric orifice area with smaller prostheses.  相似文献   
93.
94.
95.
Failure of genetically selected miniature swine to model NIDDM   总被引:2,自引:0,他引:2  
Ten young adult miniature swine from a line reported to be genetically selected for glucose intolerance and eight normal controls were obtained from Colorado State University. They were consecutively exposed to 4 mo of a high-fiber, low-fat standard swine diet; 4 mo of a high-sucrose, high-fat, low-fiber diabetogenic diet; and 4 mo of excess diabetogenic diet for obesification. Results of oral glucose tolerance and intravenous insulin tolerance tests conducted at the end of each regimen were compared. Hyperglycemia was not observed in any animals after any manipulation. Insulin sensitivity was also not influenced by diet. We conclude that F7 low-K miniature swine from this colony fail to model human non-insulin-dependent diabetes.  相似文献   
96.
Relatives of 22 schizotypal probands were evaluated for lifetime psychiatric diagnoses. Forty-four (N = 44) of the 97 available relatives were interviewed directly using the Diagnostic Interview Schedule. The rates of psychiatric diagnoses were compared with those of sixty-six (N = 66) of 140 relatives of 30 depressed patients. Family history of mental illness was ascertained by the informant method on the remainder of relatives of both proband groups. The rate of depression found in the relatives of schizotypal patients was 52% in those directly interviewed and 25.7% when informants' reports on unavailable relatives are pooled with direct interview data. These rates were not significantly higher than those found for the relatives of depressed probands (34.8% by direct interview and 21% including reports from informants). The high rates of depression in the relatives of schizotypal probands may indicate that schizotypal personality is associated with affective disorder and not only with schizophrenia. However, the high rates may be due to the presence of depressive character traits in relatives, which inflate the rates of dysthymic disorder and other chronic depressive disorders in the relatives of borderline patients.  相似文献   
97.
Results of an examination of 39 patients are described and critically assessed. An analysis of the resolving power of the method of ultrasonic angiography in pathological formations of major vessels of the neck is given.  相似文献   
98.
99.
OBJECTIVES: The aim was to assess the natural course of oral lichen lesions (OLL) among unselected, non-consulting individuals. SUBJECTS AND METHODS: A cohort of 327 subjects with OLL, confirmed in 1973-1974 during a population-based survey in two Swedish municipalities, was followed through January 2002 via record linkages with nationwide and essentially complete registers. A sample of 80 drawn from the 194 surviving subjects who still resided in the area in 1993-1995 was invited for interview and oral re-examination. RESULTS: At the end of follow-up, one case of oral cancer was detected, while 0.4 were expected. The overall mortality among subjects with OLL was not significantly different from that in the 15,817 OLL-free subjects who participated in the initial population based survey in 1973-1974. The lesion had disappeared in 14 (39%) of 36 re-examined subjects with white OLLs in 1973-1974, and four (11%) had transformed into red types. In the corresponding group of 19 with red forms initially, five (26%) had become lesion free and four (21%) had switched to white types. Although the cohort size does not permit firm conclusions regarding oral cancer risk, the natural course over up to 30 years appears to be benign in the great majority.  相似文献   
100.
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