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   2161篇
  免费   227篇
  国内免费   9篇
耳鼻咽喉   36篇
儿科学   68篇
妇产科学   39篇
基础医学   352篇
口腔科学   114篇
临床医学   213篇
内科学   373篇
皮肤病学   73篇
神经病学   103篇
特种医学   164篇
外国民族医学   48篇
外科学   219篇
综合类   64篇
预防医学   223篇
眼科学   21篇
药学   77篇
中国医学   1篇
肿瘤学   209篇
  2022年   12篇
  2021年   25篇
  2020年   15篇
  2019年   20篇
  2018年   32篇
  2017年   28篇
  2016年   31篇
  2015年   41篇
  2014年   34篇
  2013年   54篇
  2012年   65篇
  2011年   86篇
  2010年   57篇
  2009年   64篇
  2008年   79篇
  2007年   81篇
  2006年   70篇
  2005年   67篇
  2004年   80篇
  2003年   63篇
  2002年   63篇
  2001年   56篇
  2000年   56篇
  1999年   61篇
  1998年   68篇
  1997年   80篇
  1996年   72篇
  1995年   56篇
  1994年   59篇
  1993年   59篇
  1992年   67篇
  1991年   43篇
  1990年   56篇
  1989年   57篇
  1988年   53篇
  1987年   54篇
  1986年   57篇
  1985年   42篇
  1984年   24篇
  1983年   24篇
  1982年   31篇
  1981年   17篇
  1980年   19篇
  1979年   23篇
  1978年   13篇
  1977年   15篇
  1976年   19篇
  1975年   16篇
  1973年   11篇
  1967年   10篇
排序方式: 共有2397条查询结果,搜索用时 15 毫秒
1.
2.
Between January 1966 and August 1981, 159 patients with previously untreated squamous cell carcinomas of the anterior faucial pillar or retromolar trigone received definitive radiation therapy at The University of Texas M. D. Anderson Hospital and Tumor Institute. All except 11 patients were treated by external radiation including combination of electron beams with high-energy photons or 60Co to doses ranging from 60 Gy to 75 Gy. In the N0 patients, as a rule, only the ipsilateral subdigastric nodes were treated electively to a dose of 50 Gy. The 5-year determinate survival rate for the overall group was 83%. The cumulative recurrence rate showed that 92% of the patients had recurrence by 2 years. Therefore, all patients except those who died with no evidence of local disease less than 2 years after treatment were evaluated for local control. The failure rate for the evaluable patients was 29% for T1 lesions, 30% for T2 lesions, 24% for T3 lesions, and 40% for T4 lesions. After salvage surgery, which consisted of intraoral resection in one-third of the patients and of a composite operation in the other two-thirds, the ultimate failure rate was 0% for T1 lesions, 6% for T2 lesions, 8% for T3 lesions, and 20% for T4 lesions. Whereas stage was a poor indicator for treatment outcome, there was a significantly higher failure rate for infiltrative and/or ulcerated lesions (35%) than for exophytic or superficial lesions (15%). Histologic grade was of no prognostic significance, nor was there any significant difference in the failure rate for lesions originating on the anterior faucial pillar versus that for lesions on the retromolar trigone. Following radiotherapy, 30% of the patients developed some degree of bone exposure but only 5.6% (9 patients) required a segmental mandibular resection. The probability of bone exposure was not dose related and more likely reflected tumor location on the mucoperiosteum. Of the whole group, 16 patients (10%) experienced a neck failure with 8 ultimate failures after salvage surgery. Among the 16 patients who had neck failures, 13 were originally staged N0; 6 of these patients had failures that occurred in the electively treated ipsilateral subdigastric area, but the field was too small to cover the nodes adequately. Aspects of the radiotherapy techniques with combined electron and photon beams that may influence the treatment outcome are discussed.  相似文献   
3.
4.
5.
6.
7.
BACKGROUND. The distribution and correlates of serum levels of total cholesterol were studied in cross-sectional analyses of 7,439 1 to 4 year olds examined through the Arizona Department of Health Services. RESULTS. Mean cholesterol levels increased with age, and levels among 2 year olds approached those seen in adolescents. Racial and ethnic differences in cholesterol levels were observed: mean (age-adjusted) levels were 147 mg/dl among American Indians (n = 622), 153 mg/dl among Hispanics (n = 3165), 154 mg/dl among non-Hispanic whites (n = 3448), and 163 mg/dl among blacks (n = 204). Cholesterol levels were not associated either with obesity, as assessed by relative weight or the Quetelet index, or with breast-feeding during infancy. Very overweight (greater than or equal to 20 kg/m2) 3 and 4 year olds, however, tended to have higher mean levels of cholesterol than did other children. The proportion of children with borderline (170 to 199 mg/dl) or high (greater than or equal to 200 mg/dl) levels of cholesterol varied by race/ethnicity: borderline (high) levels were seen among 14% (3%) of American Indians and 29% (11%) of blacks. The proportions of white and Hispanic children having cholesterol levels between 170 and 199 mg/dl or greater than or equal to 200 mg/dl were midway between those seen among American Indians and blacks. CONCLUSION. Additional information on the interrelationships of lipids and lipoproteins may aid in the identification of children who will be at increased risk for cardiovascular disease in adulthood.  相似文献   
8.
Selachyl alcohol (SA) is a mono-oleyl glyceryl ether. It has certain biologic activities similar to those of the antihypertensive neutral renomedullary lipid (ANRL) derived from the renal papilla and its renomedullary interstitial cells (RIC). These include a vaso-depressor effect following bolus injection and a requirement for hepatic activation for the development of biological activity. In view of this similarity to ANRL, it appeared worthwhile to test the antihypertensive action of SA when given via the GI tract. Accordingly, pure SA was given either by gavage or by tube into the stomach or duodenum of one-kidney, one-clip hypertensive rats (5-10 mg per dose). The role of hepatic activation was demonstrated by comparing the BP response to bolus injection of SA and ANRL with and without the presence of an intact circulation to the liver. Administration of SA via the GI tract resulted in a significant decline in BP without tachycardia or weight loss. In the absence of a circulation to the liver, neither SA nor ANRL was active. SA appears to be an effective antihypertensive agent when given via the GI tract.  相似文献   
9.
10.
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