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   46502篇
  免费   4237篇
  国内免费   71篇
耳鼻咽喉   525篇
儿科学   1359篇
妇产科学   1073篇
基础医学   6008篇
口腔科学   1085篇
临床医学   5388篇
内科学   8792篇
皮肤病学   698篇
神经病学   4904篇
特种医学   2212篇
外国民族医学   4篇
外科学   6354篇
综合类   768篇
一般理论   34篇
预防医学   4403篇
眼科学   1179篇
药学   3150篇
  2篇
中国医学   53篇
肿瘤学   2819篇
  2021年   587篇
  2019年   556篇
  2018年   653篇
  2017年   557篇
  2016年   561篇
  2015年   657篇
  2014年   882篇
  2013年   1398篇
  2012年   1936篇
  2011年   2051篇
  2010年   1164篇
  2009年   1032篇
  2008年   1833篇
  2007年   2061篇
  2006年   1950篇
  2005年   1839篇
  2004年   1798篇
  2003年   1678篇
  2002年   1710篇
  2001年   1535篇
  2000年   1559篇
  1999年   1377篇
  1998年   581篇
  1997年   564篇
  1996年   545篇
  1995年   496篇
  1994年   432篇
  1993年   385篇
  1992年   1171篇
  1991年   1175篇
  1990年   1108篇
  1989年   1123篇
  1988年   938篇
  1987年   1055篇
  1986年   979篇
  1985年   988篇
  1984年   766篇
  1983年   626篇
  1982年   404篇
  1981年   374篇
  1980年   380篇
  1979年   702篇
  1978年   526篇
  1977年   456篇
  1976年   466篇
  1975年   400篇
  1974年   520篇
  1973年   455篇
  1972年   383篇
  1971年   363篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
A patient with an unusual granulomatous response to infection with Pneumocystis carinii is described. The diagnosis was made by open lung biopsy after two negative bronchoalveolar lavages.  相似文献   
92.
Race/ethnicity and gender differences in the drugs-violence relationship   总被引:1,自引:0,他引:1  
This article examines the drug relatedness of violent events reported by White, Black, and Hispanic male and female street drug users from New York City. The primary purpose is to determine if the drugs-violence relationship varies for these different populations of drug abusers. Drug relatedness is assessed according to a tripartite conceptual model of the general relationship between drugs and violence. Significant race/ethnicity and gender differences were found in regard to the number of violent events manifesting specific drug-related dimensions of violence, the drugs associated with these violent events, and the primary reasons for the occurrence of these events. The implications of these findings are discussed.  相似文献   
93.
BACKGROUND: Patients on hormone replacement therapy (HRT) for osteoporosis prevention rather than menopausal symptom control may be asymptomatic, despite inadequate replacement and low serum oestradiol (E2) levels. In the primary health care setting, therapeutic monitoring of HRT is not carried out routinely so that patients with serum E2 levels inadequate to protect bone may be missed. AIM: To determine the proportion of women on transdermal E2 preparations with serum E2 levels insufficient to protect bone and to assess the value of a questionnaire-derived menopausal symptom score (MSS) for detecting these patients. METHOD: A cross-sectional analysis of 45 patients aged 35-70 years using transdermal E2 preparations obtained from a computer register of 14500 patients in a suburban practice. One blood sample was obtained from each patient at the time the MSS questionnaire was completed. Serum E2 concentration was measured using a fluoroimmunoassay and compared with the MSS. Levels below 150 pmol/l were considered to be insufficient to protect bone. The diagnostic accuracy of the MSS in screening for levels below 150 pmol/l was determined using receiver operating characteristic (ROC) curve analysis. RESULTS: The median (95% CI) serum E2 was 147 pmol/l (126-198 pmol/l) and levels were below 150 pmol/l in 24 out of 45 patients. There was no difference in the MSS (median, 95% CI) between those with serum E2 < 150 pmol/l (8.5, 5.0-17) and > or = 150 pmol/l (9.0, 5.0-14; P = 0.477). The degree of association between the serum E2 and the MSS, using the Spearman rank correlation coefficient, rs (95% CI) was small and not significant (-0.04, -0.34 to 0.26; P = 0.398). ROC curve analysis revealed an area under the curve (95% CI) of 0.51 (0.33-0.68). CONCLUSIONS: More than half the women were inadequately replaced to protect against osteoporosis. Furthermore, the MSS was of no value in screening for those with low serum E2 levels. Serum E2 levels should be monitored in women on HRT for osteoporosis prevention and the E2 dosage adjusted accordingly.  相似文献   
94.
The neuropeptide galanin (GAL) influences leaming and memory processes, perhaps by inhibiting cholinergic function. We recently reported that, in the rat, the nucleus of the horizontal limb of the diagonal band (HDB) exhibits the highest level of GAL mRNA coexpression by basal forebrain (BF) cholinergic neurons and, in the HDB, virtually all GAL mRNA-expressing neurons correspond to the cholinergic cell type. Since GAL gene expression is induced across puberty in many brain regions, we used in situ hybridization histochemistry and quantitative autoradiography to assess GAL gene expression across the rostro-caudal extent of the HDB in prepubertal and adult male rats and to determine whether GAL gene expression is also regulated during maturation in this BF region. Our results show that the number of GAL mRNA-expressing cells per section is significantly reduced in the HDB with adulthood. Post-hoc analysis indicated that these age-associated differences in the number of GAL mRNA-expressing cells per section could be ascribed to the rostral and central subregions of the HDB. Age-related differences in the labeling intensity of GAL mRNA-expressing neurons were also detected in the rostral and central subregions of the HDB. No age-associated differences in GAL gene expression were found in the caudal HDB subregion. These results suggest that: (1) in contrast to other brain regions, GAL gene expression in the cholinergic BF may be negatively regulated by factors concomitant with puberty; and (2) the inhibition of cholinergic function by cosecreted GAL may be enhanced prior to puberty within cholinergic neurons of the rostral and central aspects of the HDB.  相似文献   
95.
Body pain and treatment response in late-life depression.   总被引:2,自引:0,他引:2  
OBJECTIVE: The authors investigated the influence of body pain on 1) time to treatment response and 2) suicidal ideation, in late-life depression. They hypothesized that higher levels of body pain would predict a longer time to and lower likelihood of response, and increased levels of suicidal ideation. METHODS: Subjects (N=187) were older adult outpatients (age > or =69 years), with current episodes of major depression, who were openly treated with paroxetine up to 40 mg daily and weekly interpersonal psychotherapy. Response was defined as 3 consecutive weeks of Hamilton Rating Scale for Depression at < or =10. Body pain was measured with the Bodily Pain Index of the SF-36 quality-of-life assessment. Authors used survival-analysis models on the responder sample to test the effect of body pain on response, after controlling for severity of depression. RESULTS: Overall response rate was 75.4%. Nonresponders reported more severe pain at baseline. After covarying for severity of baseline depression, no effect was found for physical pain on time-to-response or degree of suicidality. Bodily pain remained stable during acute treatment for responders, independent of depression response to combination psychotherapy and antidepressant treatment. CONCLUSIONS: Older adult patients with higher levels of physical pain can still respond to antidepressant treatment; however, reported bodily pain may be associated with a more difficult-to-treat depression.  相似文献   
96.
Severe hypokalemia in thyrotoxic periodic paralysis   总被引:1,自引:0,他引:1  
Thyrotoxic hypokalemic periodic paralysis is an uncommon but sometimes fatal disease in which early recognition and therapy may prevent untoward complications. The case of a 26-year-old Chinese man who presented to the emergency department with rapidly progressive profound weakness and severe hypokalemia (serum potassium, 1.2 mEq/L) is presented. The patient required endotracheal intubation, ventilatory assistance, and intravenous potassium administration. Emergency medical evaluation and management of this entity are discussed.  相似文献   
97.
A technique for transperineal high-dose-rate (HDR) prostate brachytherapy and needle biopsy in a standard 1.5 T MRI scanner is demonstrated. In each of eight procedures (in four patients with intermediate to high risk localized prostate cancer), four MRI-guided transperineal prostate biopsies were obtained followed by placement of 14-15 hollow transperineal catheters for HDR brachytherapy. Mean needle-placement accuracy was 2.1 mm, 95% of needle-placement errors were less than 4.0 mm, and the maximum needle-placement error was 4.4 mm. In addition to guiding the placement of biopsy needles and brachytherapy catheters, MR images were also used for brachytherapy treatment planning and optimization. Because 1.5 T MR images are directly acquired during the interventional procedure, dependence on deformable registration is reduced and online image quality is maximized.  相似文献   
98.
99.
OBJECTIVE: Many patients with haemorrhoids are investigated because of the fear of missing colorectal cancer (CRC). The aim of this study was to determine whether a primarily clinical approach regarding the need for investigation was safe and did not miss patients with CRC. PATIENTS AND METHODS: Data was collected prospectively on 589 consecutive patients with the principle diagnosis of haemorrhoids at first clinic visit. All had clinical assessment including rigid sigmoidoscopy and were treated by phenol injection or banding. They were categorized for (1) no review unless symptoms persisted -'One Stop SOS' (2) outpatient review or (3) investigation. To check for the development of CRC they were contacted by postal questionnaire or telephone interview with a minimum of one year from diagnosis and treatment. All 589 patients were cross-referenced with the Pathology database and the Hospital Information Services System. RESULTS: Four hundred and sixty-nine (80%) answered the questionnaire; 352 patients (60% of the total group) fell in the 'one stop SOS' outpatient category; 95 (16%) patients were followed up to review response to treatment for large haemorrhoids; 105 (18%) were investigated with barium enema (12%), flexible sigmoidoscopy (4%), colonoscopy (1%) and miscellaneous (1%); 37 (6%) patients were either given a haemorrhoidectomy date or referred on with a different diagnosis. No patients selected for 'one-stop' treatment developed CRC. Five (0.8%) patients were diagnosed with CRC after appropriate investigation was instituted for suspicious symptoms. One patient with distal transverse colon cancer had a delayed diagnosis as she was investigated initially by flexible sigmoidoscopy. CONCLUSION: Most patients with the primary diagnosis of symptomatic haemorrhoids do not need investigation.  相似文献   
100.
INTRODUCTION: Barrett's esophagus, a syndrome in which the squamous mucosa that normally lines the distal esophagus is replaced with columnar epithelium, is found in a small percentage of patients presenting with gastroesophageal reflux disease (GERD). The columnar epithelium may be protective, guarding people afflicted with Barrett's esophagus from experiencing symptoms related to acid reflux. The purpose of this study was to investigate whether people with Barrett's esophagus subjectively experience fewer symptoms or symptoms of decreased severity, despite sustaining greater acid exposure, than those with GERD but without Barrett's syndrome. METHODS: We conducted a chart review of patients with GERD. Criteria for inclusion in the study were esophagogastroscopy, motility testing and a 24-hour pH study. Fifty-eight patients (29 men, 29 women) fulfilled these criteria. The diagnosis of GERD was based on an abnormal 24-hour pH study (DeMeester score). Of these 58 patients, 21 (14 men, 7 women) were found to have histologically confirmed Barrett's esophagus. A questionnaire to assess the key symptoms of GERD was administered, with a severity score ranging from 0 to 3 (3 being the most severe) for each symptom. RESULTS: Patients with Barrett's esophagus experienced symptoms significantly less severe (p < 0.01) than those with GERD. Patients with Barrett's esophagus also had a greater degree of acid exposure as identified by higher DeMeester scores (p = 0.056), longer episodes of acid exposure, a greater number of long episodes (> 5 min) of acid exposure (p = 0.033) and an increased percentage of time when their pH was less than 4. Patients with Barrett's esophagus had decreased resting lower esophageal sphincter tone, and number and amplitude of peristaltic contractions. CONCLUSIONS: For patients with Barrett's esophagus, the columnar epithelium may serve a protective function in guarding against symptoms of acid reflux. This has implications for the diagnosis and management of this condition.  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