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   7659篇
  免费   274篇
  国内免费   48篇
耳鼻咽喉   56篇
儿科学   164篇
妇产科学   86篇
基础医学   1068篇
口腔科学   260篇
临床医学   384篇
内科学   1808篇
皮肤病学   160篇
神经病学   587篇
特种医学   334篇
外科学   1378篇
综合类   20篇
一般理论   1篇
预防医学   185篇
眼科学   70篇
药学   482篇
中国医学   15篇
肿瘤学   923篇
  2023年   37篇
  2022年   56篇
  2021年   117篇
  2020年   49篇
  2019年   63篇
  2018年   103篇
  2017年   81篇
  2016年   127篇
  2015年   141篇
  2014年   186篇
  2013年   221篇
  2012年   381篇
  2011年   412篇
  2010年   230篇
  2009年   212篇
  2008年   418篇
  2007年   495篇
  2006年   465篇
  2005年   566篇
  2004年   562篇
  2003年   566篇
  2002年   531篇
  2001年   92篇
  2000年   63篇
  1999年   103篇
  1998年   158篇
  1997年   142篇
  1996年   127篇
  1995年   115篇
  1994年   122篇
  1993年   102篇
  1992年   85篇
  1991年   80篇
  1990年   79篇
  1989年   56篇
  1988年   76篇
  1987年   61篇
  1986年   41篇
  1985年   50篇
  1984年   41篇
  1983年   27篇
  1982年   38篇
  1981年   45篇
  1980年   41篇
  1979年   20篇
  1978年   31篇
  1977年   19篇
  1976年   27篇
  1975年   15篇
  1972年   12篇
排序方式: 共有7981条查询结果,搜索用时 15 毫秒
991.
Passage of a colon ‘cast’ after anoabdominal rectal resection   总被引:1,自引:1,他引:1  
The authors report a case of the passage of a total colonic J-pouch "cast" per anus after anoabdominal rectal resection and colonic J-pouch-anal anastomosis. This occurred without development of cuff abscess and was not due to occlusion of the inferior mesenteric artery. This was successfully treated, with preservation of anal function, with resection of the colonic J-pouch by transanal approach.  相似文献   
992.
OBJECTIVE: Ghrelin is an acylated peptide, whose octanoyl modification is essential for its biological activities. Previous studies demonstrated that fasting plasma ghrelin levels were high in anorectic patients, suggesting ghrelin may play an important role in the pathophysiology of anorexia nervosa. However, antibodies used in previous work to measure ghrelin concentrations in human blood do not distinguish between the active form of ghrelin (active ghrelin) and desacyl ghrelin with no biological activities. Therefore, we studied plasma levels of active ghrelin during oral glucose tolerance test (OGTT) in anorectic patients, using a radioimmunoassay (RIA) specific for active ghrelin. METHODS: Active ghrelin response to OGTT was evaluated in five female anorectic patients and seven age-matched control females. All subjects were given a 75 g/225 ml glucose solution orally after overnight fasting. For RIA of active ghrelin, 1 N hydrogen chloride was added to the samples at final concentration of 0.1 N immediately after separation of plasma. RESULTS: Plasma basal levels of active ghrelin were significantly higher in anorectic patients than in controls (52.1+/-10.5 vs 21.2+/-3.1 fmol/ml, P<0.01). They were significantly decreased during OGTT in anorectic patients and in controls, reaching a nadir of 49.0+/-7.7% and 57.3+/-4.5% of the basal levels, respectively. CONCLUSION: These results suggest that hyperghrelinemia in anorectic patients is caused at least partly by increased secretion of active ghrelin and that glucose ingestion suppresses active ghrelin release in these patients.  相似文献   
993.
In goldfish, plasma gonadotropin levels increase during spawning in both males and females (GTH surge). A female-typical GTH surge induces ovulation (ovulatory surge), and a male-typical surge triggers milt production in response to sex pheromones released from ovulatory females. This study examined whether the male-typical GTH surge occurs in adult females that are implanted with 11-ketotestosterone (KT), which induces male-typical sexual behavior in adult female goldfish. When KT-implanted females were exposed to ovulatory females, a GTH surge occurred without ovulation. No GTH surge was observed when KT-females were exposed to nonovulatory females. The GTH secretion in KT-females was further characterized by exposure to 17α,20β-dihydroxy-4-pregnen-3-one (17,20-P), a female sex pheromone that induces the GTH surge in males. Exposure to waterborne 17,20-P caused an elevation of GTH levels in KT-females as well as in males. The elevation of GTH levels induced by 17,20-P exposure was abolished when the KT-females were rendered anosmic. Unlike the female-typical ovulatory GTH surge that occurs in synchrony with photoperiod and peaks in the dark phase of the day, the 17,20-P-induced surge did not show a peak in the dark phase. These results indicate that the GTH surge in KT-females is a male-typical surge. Together with a previous study showing KT-induced behavioral masculinization (N. E. Stacey and M. Kobayashi, 1996,Horm. Behav.30,434–445), this adult gonochoristic species was shown to possess sexual plasticity of brain function in behavior and GTH secretion in response to sex steroid.  相似文献   
994.
995.
Summary In a previous paper, it was stated that open lung biopsy for determination of operative indications could be recommended if pulmonary vascular resistance (PVR) were higher than 8 units · m2 in patients with ventricular septal defect (VSD) and/or patent ductus arteriosus (PDA) with severe pulmonary hypertension. In the present study, oxygen inhalation or Tolazoline administration tests with or without occlusion of ductus arteriosus were performed during cardiac catheterization in 47 patients with VSD and/or PDA with severe pulmonary hypertension. The results obtained were compared with the operability based on our histopathological diagnostic criteria. There was no correlation between the oxygen, Tolazoline, or ductus occlusion hemodynamics and the baseline hemodynamics for better prediction of the biopsy results. It was concluded that open lung biopsy should be performed for the determination of operative indication when patients with VSD and/or PDA have a PVR higher than 8 units.m2, and if the PVR is greater than 4 units.m2 with the oxygen inhalation test or 7 units.m2 with the Tolazoline test.  相似文献   
996.
High dose-dobutamine (DOB) has been previously used as a pharmacological stress test to evaluate wall motion abnormalities. As a result, recent stress echocardiography with low-dose DOB has been reported to be valuable for investigating stunned myocardium after thrombolysis. However, echocardiography requires an operator's skill and experience to evaluate wall motion abnormalities which are subjectively determined by the observer. In contrast, ultrafast computed tomography (UFCT) does not necessarily require extreme technical skill and experience. To evaluate the feasibility of stress UFCT with low-dose DOB, we scanned 10 normal subjects along the short-axis by 8-slice-multicine mode. After scanning at rest for baseline, we scanned during the administration of 4 and 8 m?g/kg/min of DOB, respectively, for 5 min. Ejection fraction, contraction, and thickening were higher during 8 m?g/kg/min of DOB than during 4 m?g/kg/min of DOB and baseline, while the above values were higher during 4 m?g/kg/min of DOB than during baseline (p < 0.01). It was possible to detect changes of cardiac function and wall motion due to low-dose DOB by UFCT. We therefore conclude that UFCT is a reliable modality for evaluating cardiac function and wall motion for low-dose DOB stress test because of its excellent spatial and contrast resolution.  相似文献   
997.
Summary Twins with pulmonary atresia, intact ventricular septum, and hypoplastic right ventricle associated with underdeveloped and discontinuous left pulmonary artery are described. Operations to connect the left pulmonary artery to the main pulmonary trunk, with subsequent biventricular repair assisted by bidirectional cavopulmonary anastomosis and atrial fenestration were performed. Follow-up catheterization proved spontaneous closure of the fenestration in one patient. Both patients have been in a satisfactory condition for 3 years since operation.  相似文献   
998.
Objectives: The aim of the present study was to investigate the factors that contribute to the progression of synovial chondromatosis in the temporomandibular joint (TMJ).

Methods: The authors investigated the expression of CD105 and CD90 in specimens from 17 patients with synovial chondromatosis in the TMJ, using immunohistochemical staining, and expression of CD105 and CD90 in cartilaginous nodules was scored semiquantitatively.

Results: The expression of CD105 and CD90 was found in almost all the cases. In particular, the expression of CD90 in cartilaginous nodules significantly decreased with the progression of synovial chondromatosis.

Discussion: The factors that determine progression of synovial chondromatosis are not fully understood. The results of this study suggest that CD90 may play an important role in the progression of synovial chondromatosis in the TMJ.  相似文献   

999.
BACKGROUND: The relationship of changes in blood glucose concentrations after admission to left ventricular (LV) dysfunction in patients with recanalized anterior acute myocardial infarction (AMI) remains unclear. METHODS AND RESULTS: Blood glucose concentrations were measured on admission and 24 h after symptom onset in 210 patients with recanalized anterior AMI within 6 h of symptom onset. Of them, 142 had hyperglycemia on admission, defined as a blood glucose >or=8.9 mmol/L, and 68 patients did not. Among the patients with admission hyperglycemia, 49 had persistent hyperglycemia, defined as a blood glucose >or=8.9 mmol/L 24 h after onset, and 93 did not. The incidences of myocardial blush grade of 0/1 after recanalization indicating impaired myocardial perfusion (71%), and peak creatine kinase concentration (5,631+/-2,855 mU/ml) were higher and predischarge LV function (43+/-11%) was lower in patients with persistent hyperglycemia than in those without (p<0.01). Multivariate analysis showed that persistent hyperglycemia was independently associated with LV dysfunction, defined as a predischarge LV ejection fraction 相似文献   
1000.
No association of familial adenomatous polyposis (FAP) and hereditary spherocytosis (HS) has been reported, both of which are inherited in an autosomal dominant manner. We present the first reported case of FAP with spherocytosis and construct the family pedigree. In the patient's pedigree, both FAP and spherocytosis were inherited in an autosomal dominant trait. In the 34-year-old Japanese proband's leukocytes, we found no abnormal chromosomal band, and a germline mutation of the APC gene was not detected. All possible genes reported to be linked to HS were located far from chromosome 5q on which the APC gene is located. Although it is unknown if erythrocyte membrane disorder is an additional phenotype of FAP, to the best of our knowledge, this is the first documentation of FAP associated with spherocytosis. Received: July 11, 2001 / Accepted: November 2, 2001 Reprint requests to: K. Hirata  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