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   21532篇
  免费   2404篇
  国内免费   30篇
耳鼻咽喉   167篇
儿科学   623篇
妇产科学   537篇
基础医学   2660篇
口腔科学   426篇
临床医学   2220篇
内科学   4132篇
皮肤病学   199篇
神经病学   2068篇
特种医学   850篇
外科学   2893篇
综合类   374篇
一般理论   14篇
预防医学   3714篇
眼科学   286篇
药学   1192篇
中国医学   5篇
肿瘤学   1606篇
  2022年   153篇
  2021年   287篇
  2020年   252篇
  2019年   293篇
  2018年   392篇
  2017年   333篇
  2016年   361篇
  2015年   368篇
  2014年   475篇
  2013年   821篇
  2012年   883篇
  2011年   958篇
  2010年   599篇
  2009年   673篇
  2008年   872篇
  2007年   923篇
  2006年   906篇
  2005年   958篇
  2004年   883篇
  2003年   811篇
  2002年   843篇
  2001年   712篇
  2000年   700篇
  1999年   730篇
  1998年   407篇
  1997年   407篇
  1996年   424篇
  1995年   313篇
  1994年   250篇
  1993年   302篇
  1992年   447篇
  1991年   429篇
  1990年   423篇
  1989年   456篇
  1988年   372篇
  1987年   370篇
  1986年   366篇
  1985年   329篇
  1984年   263篇
  1983年   222篇
  1982年   180篇
  1981年   159篇
  1979年   220篇
  1978年   182篇
  1977年   149篇
  1976年   154篇
  1974年   181篇
  1973年   140篇
  1972年   154篇
  1971年   141篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
91.
This study describes changes observed during a 2-year period in participants enrolled in The Solution Method, a developmental skills training program for adult weight management. This Intervention is the adult application of a model of treatment previously used only in the management of pediatric obesity (The Shapedown Program). Developmental skills training integrates understandings and methods from developmental, family systems, biomedical, genetic, and behavioral theories of the etiology of obesity. Twenty-two subjects (mean age=43.4±8.5 years and mean body mass index=33.1+5.3) completed a group intervention based on this method, which was conducted by a registered dietitian and a mental health professional. Questionnaire responses indicated the extent to which their weight was a medical and/ or psychosocial risk. Subjects attended 2-hour weekly sessions for an average of 18 weeks during which they were trained in six developmental skills: strong nurturing, effective limits, body pride, good health, balanced eating, and mastery living. Data, which were collected at the beginning of treatment and at 3, 6, 12, and 24 months, included weight, blood pressure, 7-day exercise recalls, and responses to depression and functioning (psychosocial, vocational, and economic) questionnaires. Participants’ weights decreased throughout the 2-year period of the study: mean weight change was −4.2 kg (3 months), −6.0 kg (6 months), −7.0 kg (12 months), and −7.9 kg (24 months). In addition, compared with baseline values, systolic and diastolic blood pressure, exercise, and depression improved throughout the study period. These improvements were statistically significant at 24 months for weight (p<.01), systolic blood pressure (p<.02), diastolic blood pressure (p<.001), and exercise (p<.001); the results were not statistically significant for depression. Most participants reported improvement in a broad range of aspects of functioning. We conclude that this application of developmental skills training for adult weight management may produce significant long-term beneficial effects. J Am Diet Assoc. 1997;97:1133–1138.  相似文献   
92.
Objective To determine whether reduced serum or plasma protein and micronutrient levels are common in children infected with the human immunodeficiency virus (HIV) and whether these levels are different in children with growth retardation compared to those with normal growth.

Subjects Children were separated into three groups: (a) HIV-infected with growth retardation (HIV+Gr); (b) HIV-infected with normal growth (HIV+); (c) HIV-uninfected with normal growth (HIV-). All children were afebrile and free of acute infection at the time of study. During a 24-hour stay in the Pediatric Clinical Research Unit, blood was drawn for analysis of total protein, albumin, zinc, selenium, and vitamin A levels; growth measurements were obtained; and dietary intake was assessed by 24-hour weighed food intake and 24-hour dietary recall.

Statistical analysis Mean differences between groups were assessed by analysis of variance, and differences in the frequency of nutrient deficiency were determined by χ2 analysis.

Results Thirty-eight children between 2 and 11 years of age were studied: 10 HIV+Gr, 18 HIV+, and 10 HIV-. No statistically significantly differences were noted in mean levels of albumin, prealbumin, zinc, and selenium. Mean serum level of vitamin A was significantly higher in the HIV+Gr group than in the other two groups. There were no significant differences between groups in the frequency of deficiency for any nutrient studied. Mean energy and nutrient intake was similar among groups.

Applications/conclusions Abnormal serum or plasma protein or micronutrient levels were uncommon in this cohort of HIV-infected children, even in children with growth retardation. Routine monitoring of the level of proteins and micronutrients studied is unnecessary in the absence of specific clinical indicators of deficiency. J Am Diet Assoc. 1997-97:1377-1381.  相似文献   

93.
Background: Morbid obesity is a serious disease that afflicts over five million Americans, threatening their health with such co-morbidities as diabetes, arthritis, pulmonary failure and stroke. Surgery is the only effective therapy, providing long-term control of weight, diabetes, pulmonary failure, and hypertension for as long as 14 years. Because the operation presents a major expense, this study examined whether X-ray examination of the gut could be omitted safely as a cost-saving measure. Methods: The records of 814 consecutive morbidly obese patients who underwent gastric bypass were reviewed to determine: (1) whether these individuals had undergone an upper gastro-intestinal (GI) series, and (2) if these studies influenced therapy or caused cancellation or postponement of surgery. Results: Of the 814 patients, 657 (80.7%) underwent a preoperative GI radiography. Of these examinations, 393 (59.8%) were normal, with the following abnormalities in the remaining 264: hiatal hernia, 164; esophageal reflux, 39; Schatzki's ring, 18; small bowel diverticula, four; renal stones, four; malrotation, three; gall stones, two; pyloric ulcer, one; possible pelvic mass, one; calcified leiomyoma, one; and dysphagial lusoria, one. None of these findings resulted in cancellation or a delay in surgery. Conclusions: The upper GI series can be safely omitted from the routine preoperative evaluation of patients undergoing gastric bypass. At a cost of $741.00 per examination, this change represents significant potential savings. Similar evaluations of other routine preoperative tests may well provide a better basis for the evaluation of these complex patients.  相似文献   
94.
Objective The effects of a computer-assisted instruction (CAI) tutorial program on learning clinical reasoning skills were compared in undergraduate dietetics students.Design A drill-and-practice program to control for time on task, a tutorial program, and a simulation program, as the test vehicle, were developed. The tutorial and simulation programs presented data on a patient with cardiovascular disease.Setting Subjects were tested in 30 undergraduate dietetics programs.Subjects Participants were 413 undergraduate diet therapy students enrolled in a coordinated program in dietetics (CPD) or a didactic program in dietetics (DPD).Intervention After completion of lectures on cardiovascular disease, subjects were given the drill-and-practice program plus a simulation test (group 1), the tutorial plus a simulation test (group 2), or the simulation test only (group 3).Main outcome measures Scores on the simulation test were compared. Variables included type of CAI, dietetics program, year in school, computer experience, and experience using a medical chart. Mastery of objectives related to lower- and higher-level clinical reasoning skills introduced in the tutorial program was compared.Statistical analysis One-way analysis of variance and Student-Newman Keuls tests were conducted to determine any differences among the three groups. Reliability was determined using the Kuder-Richardson Formula 20.Results The reliability coefficient of the simulation test was 0.93. Group 2 scored higher on the simulation test than group 1 or group 3. As a group, the CPD students scored higher than the DPD students. When CPD and DPD students were divided into the three experimental groups, there was no significant difference between the CPD and DPD student simulation scores. Group 2 mastered all objectives for lower-level reasoning skills and the higher-level decision-making objective better than groups 1 and 3.Applications/conclusions A computer tutorial program enhanced clinical reasoning skills in undergraduate dietetics students. This type of program could be used to supplement many topics taught in diet therapy and provide DPD students with experiential learning before their clinical intern practicums. J Am Diet Assoc. 1995; 95:868–873.  相似文献   
95.
96.
In 1987, die Department of Health in the UK set up a working party to identify reasons contributing to a shortfall in donor organs. One recommendation was reimbursement to the District Health Authorities for costs incurred in providing the donor organs. The figure chosen was not to be seen as an incentive to donate organs, merely as an appropriate compensation for the costs incurred. There would be no direct payment to doctors, trustees or relatives of the donor. With the development of the competitive health care environment in the United Kingdom, the reimbursement of donating hospital costs is being considered with these data.  相似文献   
97.
98.
STUDY OBJECTIVE--A chemical spill from an oil refinery exposed the local community to more than 40,000 lb of highly toxic and corrosive hydrofluoric acid. A community based symptom prevalence study found an association between exposure and physical symptoms: the psychological impact of the disaster and its potential effect on the reporting of physical symptoms is examined here. DESIGN--The study used a population based survey design consisting of two phases: phase I, the exposure phase, and, phase II, the symptom prevalence phase. SUBJECTS--In phase I, information indicative of exposure was collected on 10,811 individuals in a door to door survey of a geographically defined area. In phase II, symptom prevalence information was gathered through in-person interviews with 2509 subjects selected from the phase I census in a sampling scheme that balanced across the exposure categories with regard to age, gender, and predisposition. The refusal rate in both phases was < 5%. MEASUREMENT AND MAIN RESULTS--Stepwise logistic regression analyses were used to assess the relative predictive importance of psychological variables and hydrofluoric acid exposure in explaining the reported physical symptoms two years after the disaster. The findings show a linear relationship between the level of hydrofluoric acid exposure and the degree of psychological stress two years after the accident. High exposure had a long term (more than two years) impact on physical health for some self reported symptoms, even after controlling for the psychological impact. Some physical symptom reports, however, were better explained by psychological status than by exposure to hydrofluoric acid. The physical symptoms for which exposure was the major predictor were those for which the biological plausibility of a relationship with hydrofluoric acid exposure was direct. CONCLUSIONS--Measures of psychological status should be included in symptom studies of health sequelae to man-made disasters so that the physical effects of exposure can be more accurately assessed.  相似文献   
99.
100.
Epiderrnolysis bullosa (EB), a heterogeneous group of rare, inherited disorders, is manifested by recurrent blistering of the skin induced by the slightest trauma. Little information exists regarding the nutrition management of patients with EB. This study presents information on growth, identifies potential nutrition problems, and provides guidelines for nutrition management of persons with EB. Eighty patients attending a dermatology clinic for EB patients are described. Severity of disease ranged from mild blistering of the knees, elbows, and feet to extensive blistering and scarring of the skin and entire gastrointestinal tract. Of the 18 children with EB simplex, which is a mild form of the disease, 4 (22%) were at nutritional risk. None of the 13 adults with EB simplex were underweight and 8 (62%) were overweight. Of the patients with the more severe forms of EB, 27 of the 35 (77%) children with dystrophic EB and 4 of the 7 (57%) children with junctional EB were at risk for malnutrition. Of the 7 adults with dystrophic EB, 6 (86%) were underweight. Common nutrition problems included protein-energy malnutrition, chewing and swallowing problems, constipation, anemia, and vitamin/mineral deficiencies. When nutrition care protocols address these problems, growth, development, and nutritional status can improve. For those with severe nutrition problems, gastrostomy feeding or similar nutrition therapies should be considered. J Am Diet Assoc. 1995; 95:575-579.  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