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   19994篇
  免费   1780篇
  国内免费   30篇
耳鼻咽喉   104篇
儿科学   635篇
妇产科学   542篇
基础医学   2898篇
口腔科学   290篇
临床医学   2596篇
内科学   3891篇
皮肤病学   441篇
神经病学   1925篇
特种医学   783篇
外科学   2525篇
综合类   611篇
一般理论   15篇
预防医学   1674篇
眼科学   263篇
药学   1291篇
中国医学   15篇
肿瘤学   1305篇
  2021年   308篇
  2020年   215篇
  2019年   321篇
  2018年   370篇
  2017年   300篇
  2016年   283篇
  2015年   313篇
  2014年   454篇
  2013年   670篇
  2012年   937篇
  2011年   903篇
  2010年   518篇
  2009年   501篇
  2008年   869篇
  2007年   899篇
  2006年   906篇
  2005年   820篇
  2004年   838篇
  2003年   793篇
  2002年   678篇
  2001年   684篇
  2000年   719篇
  1999年   627篇
  1998年   242篇
  1997年   204篇
  1996年   217篇
  1995年   201篇
  1994年   191篇
  1993年   182篇
  1992年   468篇
  1991年   451篇
  1990年   419篇
  1989年   380篇
  1988年   362篇
  1987年   403篇
  1986年   365篇
  1985年   371篇
  1984年   294篇
  1983年   254篇
  1982年   164篇
  1981年   165篇
  1980年   135篇
  1979年   243篇
  1978年   201篇
  1977年   144篇
  1975年   116篇
  1974年   166篇
  1973年   162篇
  1972年   153篇
  1971年   133篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
Choice of a childbirth method after cesarean   总被引:1,自引:0,他引:1  
Concern about the rising cesarean-section rate and the high percentage of elective repeat cesareans led to an exploratory, retrospective examination of women's decision-making about a childbirth method after cesarean. Fifty women who had delivered by a repeat cesarean (RC) or vaginal birth after cesarean (VBAC) participated in a telephone interview. Three questions were addressed: (1) who made the decision for a birth method; (2) what factors were associated with the choice of method; and (3) was the choice of method associated with the actual method of delivery? The majority of women (90%) perceived that they were the primary decision-maker for a birth method, and choice of birth method was positively associated with actual method of delivery. The major reason for VBAC choice was to experience a vaginal birth, whereas the primary reason for RC choice was to avoid an unsuccessful labor. Other factors associated with choice of a birth method were: sources of information and support, beliefs, previous cesarean experience and locus of control. These findings have important implications for enhancing women's health-care decision-making, as well as for reducing the rate of repeat-cesarean deliveries.  相似文献   
32.
33.
OBJECTIVE: To investigate peripheral nasal pathology as a contributor to olfactory impairment in DS. STUDY DESIGN: Twenty DS and 16 non-DS subjects were recruited. Nasal history and symptoms were assessed by self-report or informant. Olfactory threshold, odor identification, and nasal endoscopy were assessed on each subject. RESULTS: DS subjects were impaired on olfactory threshold (P<0.0001) and odor identification (P<0.001). Although DS subjects tended toward upper-respiratory infections, sleep-disordered breathing, and nasal itching, differences were not significant (P=0.07, 0.06, and 0.058, respectively). There were no significant differences on self-reported nasal history or symptoms. Endoscopy showed equivalent health in DS and control subjects. CONCLUSION: This DS population shows olfactory impairment. However, nasal health is comparable in DS subjects and controls. Nasal dysfunction is unlikely to contribute to olfactory impairment in DS. SIGNIFICANCE: Olfactory deficits in DS appear to be secondary to central, rather than rhinologic, pathology. EBM rating: B-2b.  相似文献   
34.
The relation of dizziness to functional decline   总被引:2,自引:0,他引:2  
OBJECTIVE: to assess the effect of dizziness on the probability that an older person will die or become functionally disabled within 2 years. Dizziness is a common symptom for which the prognosis is uncertain. This report compares the prognoses for dizzy and not-dizzy older people in order to assist clinicians who diagnose and treat these patients. DESIGN: a prospective study of a representative sample of elderly (70+) non-institutionalized Americans. Elderly subjects (n = 3,798) in the Longitudinal Study of Aging (LSOA) were asked questions about the presence of dizziness, medical conditions, and functional disability in 1984. The cohort was reinterviewed about functional disability in 1986. OUTCOME MEASURE: transition from functional ability to disability after 2 years. RESULTS: Bivariate analyses showed that dizziness predicts functional decline but not mortality. Multivariate models revealed that age, race, sensory impairment, vascular disease, and other morbidity are independent predictors of becoming disabled. Controlling for these potential confounders, dizziness does not predict an increased probability of becoming disabled. CONCLUSION: Elderly people who are dizzy should be evaluated for the presence of these related conditions.  相似文献   
35.
The current study evaluated psychosocial variables that may contribute to the experience of headache in college adults. One hundred ninety-nine participants, 103 women and 96 men, completed head pain logs for 4 weeks after completing measures assessing psychosocial variables. Multiple regression analyses indicated that level of emotional functioning, perception of stress, and gender were predictive of future headache frequency, intensity, and duration. Family history and health habits did not predict headache activity. These findings are consistent with research investigating psychosocial variables and headache activity.  相似文献   
36.
Summary Thirty-one patients with stage IIIB or IV non-small cell lung cancer (NSCLC) were treated with intravenous 10-EdAM on a weekly basis. The starting dose was 80 mg/m2, with subsequent doses adjusted depending on evidence of toxicity. There were 20 men and 11 women with a median age of 58 years (range, 33–75). Response was evaluated in 30 patients, 5 with evaluable but not measurable tumors and 25 with measurable indicator lesions. There were no complete remissions; 3 patients achieved partial remission. Nine patients had a minor response, 6 showed no change, and 12 had progressive disease. Median survival for all 31 patients was 43 weeks (range, 12–65&#x002B;). During the first 3-week period, the 10-EdAM dose was reduced or withheld in 19 patients (because of stomatitis in 12, SGPT elevation in 3, skin rash in 2, and granulocytopenia in 2), escalated in 11 patients, and unchanged in 1 patient. A mean of 34–88 mg/m2of 10-EdAM (median, 50) was given per week during the first 5-week period. Myelotoxicity was infrequent and there was no significant nephrotoxicity. Considering the modest side effects of this treatment and the conservative dose-modification schedule which mandated substantial dose reductions, we conclude that 10-EdAM is a promising antitumor agent for NSCLC.  相似文献   
37.
38.
We describe a simple, rapid, and semiautomated method of MR analysis based on mathematical modeling of MR pixel intensity histograms. The method is shown to be accurate and reliable for regional analysis of brain, central, and subarachnoid CSF volumes. Application of the method to five young and six older subjects revealed significant age-related changes in regional brain volumes whereas no difference was found for traced central CSF volumes or subarachnoid CSF volumes. We conclude that this is a simple method that can be applied to further studies of quantification of brain structure in healthy aging and brain disease.  相似文献   
39.
40.
OBJECTIVE: To compare the immunogenicity of four Haemophilus influenzae type b (Hib) conjugate vaccines in different populations of 17- to 19-month-old children in the United States. DESIGN: Four immunogenicity trials with sera were assayed in one laboratory. Trials 1 and 2 each compared one vaccine in two regions, and trials 3 and 4 were randomized comparisons of multiple vaccines within a region. SUBJECTS: A convenience sample of 313 healthy children recruited from pediatric practices in Minneapolis, Minn., Dallas and Houston, Tex., and Sellersville, Pa. MEASUREMENTS AND RESULTS: Children with prevaccination antibody greater than 0.15 microgram/ml showed higher antibody responses to vaccination than children with less than or equal to 0.15 microgram/ml (p less than 0.001). Among the former, there were no significant differences in antibody response to vaccination with the different conjugates within any of the trials. Among children with less than or equal to 0.15 microgram/ml of antibody before vaccination, there were no significant differences in the geometric mean antibody responses of children in trial 1 vaccinated with polyribosylribitol phosphate-diphtheria toxoid (PRP-D) in Dallas or in Minneapolis, or of children in trial 3 in Dallas randomly assigned to receive Hib oligosaccharide-CRM197 (HbOC) or PRP-D. In contrast, in trial 2, children given PRP-tetanus toxoid (PRP-T) in Pennsylvania had a significantly higher geometric mean antibody response than children given PRP-T in Houston (13.5 vs 3.0 micrograms/ml; p = 0.005). In trial 4 in Minneapolis, the geometric mean antibody response was highest in children randomly assigned to receive PRP-outer membrane protein (OMP) (9.3 micrograms/ml), followed by PRP-D (5.0 micrograms/ml) and HbOC (2.3 micrograms/ml) (PRP-OMP vs HbOC; p = 0.005). In all four trials, IgG1 responses predominated compared with IgG2 responses. CONCLUSIONS: All four conjugate vaccines are immunogenic in children 17 to 19 months of age. However, the magnitude of the anticapsular antibody response varied by vaccine type, the level of antibody in prevaccination sera, and geographic location.  相似文献   
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