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   55022篇
  免费   7797篇
  国内免费   129篇
耳鼻咽喉   954篇
儿科学   1928篇
妇产科学   1608篇
基础医学   4847篇
口腔科学   1547篇
临床医学   9894篇
内科学   12701篇
皮肤病学   733篇
神经病学   4419篇
特种医学   1043篇
外国民族医学   1篇
外科学   5320篇
综合类   382篇
现状与发展   2篇
一般理论   49篇
预防医学   8823篇
眼科学   665篇
药学   2561篇
中国医学   44篇
肿瘤学   5427篇
  2024年   183篇
  2023年   1339篇
  2022年   799篇
  2021年   1491篇
  2020年   1762篇
  2019年   1329篇
  2018年   2162篇
  2017年   1959篇
  2016年   2229篇
  2015年   2268篇
  2014年   3225篇
  2013年   4164篇
  2012年   3663篇
  2011年   3757篇
  2010年   2763篇
  2009年   3015篇
  2008年   3338篇
  2007年   3150篇
  2006年   3391篇
  2005年   2979篇
  2004年   2705篇
  2003年   2359篇
  2002年   2249篇
  2001年   505篇
  2000年   435篇
  1999年   516篇
  1998年   747篇
  1997年   578篇
  1996年   487篇
  1995年   395篇
  1994年   365篇
  1993年   316篇
  1992年   238篇
  1991年   202篇
  1990年   198篇
  1989年   184篇
  1988年   154篇
  1987年   131篇
  1986年   141篇
  1985年   136篇
  1984年   142篇
  1983年   116篇
  1982年   107篇
  1981年   110篇
  1980年   86篇
  1979年   53篇
  1978年   45篇
  1977年   55篇
  1976年   34篇
  1975年   40篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
91.
There have been few reports of relative rates of provision of dental health services in rural and urban settings, a comparative measure of access to care in these populations. One part of a statewide survey of active North Carolina general dentists (n=959, response rate=47%) was designed to quantify provision of prosthetic services. To determine contrasting rural and urban rates, responses were analyzed according to dentists'self-report of practice city size using analysis of covariance with percent of insured patients in the practice as the covariate. Mean per-patient-visit rates for crowns, fixed partial dentures, removable partial dentures, and extractions, as well as the distributions of treatment following tooth extraction, differed by city size, with practitioners in the smallest cities reporting treatment distributions reflecting more frequent loss of teeth and less frequent replacement. These differences in patterns of prosthetic care echo the limited existing information describing oral health status, provider supply, and receipt of care, all of which suggest that differential levels of access to care exist and lead to differences in oral health outcomes.  相似文献   
92.
Alexithymia was measured in non-treatment seeking, community-dwelling Holocaust survivors using the Toronto Alexithymia Scale—Twenty Item Version (TAS-20). Scores of survivors with (n = 30) and without (n = 26) posttraumatic stress disorder (PTSD) were compared, and associations among alexithymia, severity of trauma, and severity of PTSD symptoms were determined. Survivors with PTSD had significantly higher scores on the TAS-20 compared to survivors without PTSD. TAS-20 scores were significantly associated with severity of PTSD symptoms, but not with severity of trauma. This study adds to our knowledge of the relationship between alexithymia and trauma by demonstrating that this characteristic is related to the presence of posttraumatic symptoms and not simply exposure to trauma.  相似文献   
93.
31P, 1H and lactate spectroscopic imaging was used to evaluate the effects of hypothermia on focal cerebral ischemia produced by middle cerebral artery occlusion. The effects on high energy phosphate metabolism, pH, lactate and NAA were investigated in 24 spontaneously hypertensive rats subjected to either permanent or transient ischemia. Under either normothermic (37.5°C) or hypothermic (32°C) conditions, with permanent 6-h occlusion, there was little difference between groups in either the NMR measurements or the volume of infarction. In animals that underwent 3 h of ischemia followed by 12 h of reperfusion, the ischemic changes in lactate, pH, NAA, and high-energy phosphate returned toward control values, and there was a protective effect of hypothermia (infarct volume of 211 ± 26 and 40 ± 14 mm3 in normothermic and hypothermic groups, respectively). Thus, hypothermia did not ameliorate the changes in lactate, pH, NAA, or high energy phosphate levels occurring during ischemia, however, during reperfusion there was an improvement in both the recovery of these metabolites and pathological outcome in hypothermic compared with normothermic animals.  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.
Because attitudes concerning a topic can diminish the effectiveness of educational materials, previously identified attitudes concerning calcium intake were explored through focus group interviews during the developmental stages of calcium education materials. Although four focus groups of six to seven participants were planned, each of the four groups consisted of two to six women. All focus groups followed the same format, lasting for 60–90 min; questions progressed from the general to more specific. The focus groups revealed several attitudinal barriers toward dietary behavioural change, including lack of prior interest in the topic and lack of time. Attitudes about dairy calcium included the belief that dairy foods were high in fat and should be avoided, and the belief that dairy foods would cause stomach upsets. Also, neither younger nor older women felt that osteoporosis was a problem their age group needed to address. Readability scales were not necessarily predictive of preference. This study shows that focus group interviews make a valuable contribution to planning and evaluating nutrition education materials.  相似文献   
96.
Long-term outcome of completion gastrectomy for nonmalignant disease   总被引:1,自引:1,他引:0  
Between 1989 and 1995 we performed completion gastrectomy for non-malignant disease in 21 patients (11 men and 10 women, mean age 48.4 years). These patients had undergone a total of 48 prior gastric operations. Indications for completion gastrectomy in this group were anastomotic ulceration with stricture in eight patients, alkaline reflux gastritis and/or esophagitis in eight, postsurgical gastroparesis in two, gastroesophageal necrosis in two, and gastrocutaneous fistula in one. Major preoperative symptoms included nausea and vomiting in 16 cases, abdominal pain in 15, dysphagia in 14, heartburn in seven, and weight loss in five. Following completion gastrectomy, five patients (24%) had serious complications and there was one postoperative death (5%). Five patients were lost to follow-up. For the remaining 15 patients, mean follow-up has been 30 months with a range of 1 to 70 months. These patients were all interviewed and eight (53%) report significant improvement, two (13%) report moderate improvement, and four (27%) report no improvement; one patient (7%) has had worsening of symptoms since undergoing completion gastrectomy. The average body weight index was essentially unchanged after completion gastrectomy. We conclude that completion gastrectomy with Roux-en-Y esophagojejunostomy results in a favorable outcome in the majority of selected patients with diseases of the foregut who are unresponsive to less radical treatment. Presented at the Thirty-Seventh Annual Meeting of The Society for Surgery of the Alimentary Tract, San Francisco, Calif., May 19–22, 1996.  相似文献   
97.
This article suggests that the United States educational system needs significant changes. The goal of the article is to present a basic educational philosophy that would facilitate this reform. Specifically, education should be viewed as not only a means to an end that teaches basic skills for employment, but also as a process that enhances social development and self-actualization. Recommendations are offered to achieve this important goal.  相似文献   
98.
In this longitudinal study of a random sample of North Carolinians over the age of 65 and living in their homes, 325 blacks and 280 whites were examined and interviewed 18 months after baseline examinations. Coronal caries incidence was greater among whites than blacks. The increment due to teeth becoming root fragments were similar for both races; however, there were more newly crowned teeth among whites. Newly crowned surfaces were not used as part of the caries increment in logistic regression models to investigate potential risk predictors. For blacks, caries development over the 18-month period was associated with a higher lactobacillus score and more coronal caries at baseline, more previously filled coronal surfaces, and lack of active membership in clubs or other groups. For whites, having no self-reported tooth sensitivity, having a lower socioeconomic index score, taking antihistamine medications at baseline, and having the perception of more problems after the age of 40 than before were all associated with the development of coronal caries.  相似文献   
99.
Appendicitis is the commonest acute surgical emergency of childhood, and occurs in approximately 2–4 per 1000 infants. It is usually seen in infants older than 5 years but can occur at any age. Atypical clinical findings are seen in 30–50% of children, especially the younger ones, and often leads to a delayed diagnosis. Preoperative clinical assessment alone has yielded an accuracy ranging between 70 and 90% but is associated with a normal appendectomy rate of 13–25%. Preoperative imaging using the graded compression US technique and/or different helical CT techniques has been able to reduce this rate to 3–7% without an increase in perforation rate. An extensive review of the literature revealed several papers examining the accuracy of different imaging modalities and strategies of acute appendicitis in children. The reported sensitivity of US varied between 87 and 95%, vs 95–97% for helical CT, while the specificity ranged between 85 and 98% for US and 94 and 97% for helical CT. Only one truly randomised study was found, showing that compared with US alone, a combination of US and helical CT increased the sensitivity from 86 to 99%, while the specificity decreased from 95 to 89%. We conclude that imaging should be performed in all children with suspected appendicitis and that US should be the initial procedure with CT as a complementary tool.  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