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   296061篇
  免费   17219篇
  国内免费   414篇
耳鼻咽喉   4205篇
儿科学   10283篇
妇产科学   10243篇
基础医学   44945篇
口腔科学   7496篇
临床医学   24147篇
内科学   55749篇
皮肤病学   6309篇
神经病学   20992篇
特种医学   11610篇
外国民族医学   43篇
外科学   46650篇
综合类   7765篇
现状与发展   1篇
一般理论   160篇
预防医学   19893篇
眼科学   6943篇
药学   20865篇
中国医学   787篇
肿瘤学   14608篇
  2018年   3611篇
  2017年   2650篇
  2016年   3069篇
  2015年   3486篇
  2014年   4569篇
  2013年   7198篇
  2012年   9051篇
  2011年   9437篇
  2010年   6120篇
  2009年   5542篇
  2008年   8659篇
  2007年   9507篇
  2006年   9348篇
  2005年   8944篇
  2004年   8654篇
  2003年   8157篇
  2002年   7753篇
  2001年   13318篇
  2000年   13646篇
  1999年   11415篇
  1998年   3022篇
  1997年   2788篇
  1996年   2633篇
  1995年   2544篇
  1994年   2342篇
  1992年   8312篇
  1991年   8449篇
  1990年   8259篇
  1989年   8075篇
  1988年   7313篇
  1987年   7071篇
  1986年   6719篇
  1985年   6514篇
  1984年   4760篇
  1983年   4118篇
  1982年   2469篇
  1979年   4427篇
  1978年   3228篇
  1977年   2731篇
  1976年   2503篇
  1975年   2833篇
  1974年   3352篇
  1973年   3362篇
  1972年   3118篇
  1971年   2948篇
  1970年   2838篇
  1969年   2581篇
  1968年   2538篇
  1967年   2373篇
  1966年   2264篇
排序方式: 共有10000条查询结果,搜索用时 18 毫秒
71.
Thirty-one full-term newborn babies were investigated in order to establish reference values for ionized calcium. Only children fulfilling certain optimality criteria (with best possible maternal and infant conditions and uncomplicated pregnancy and delivery) were included. All infants were breast fed. Capillary blood for analysis of ionized calcium was collected by heel puncture on day 1 (6-36 h post partum, p.p.), day 3 (60-84 h p.p.) and day 5 (108-132 h p.p.). Ionized calcium was measured with a semi-automatic electrode system ICA 1 (Radiometer A/S, Copenhagen, Denmark). The reference ranges (mean +/- 2 SD) for days 1, 3 and 5 were 1.05-1.37, 1.10-1.42 and 1.20-1.48 mmol/l, respectively. The mean ionized calcium concentration on day 1 was significantly lower than on days 3 and 5. Reference values are also given for total calcium, magnesium and phosphate. We emphasize that it is impossible to calculate ionized calcium from total calcium or vice versa.  相似文献   
72.
73.
74.
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   
75.
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   
76.
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   
77.
78.
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   
79.
80.
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