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   1294篇
  免费   56篇
  国内免费   4篇
耳鼻咽喉   64篇
儿科学   61篇
妇产科学   22篇
基础医学   177篇
口腔科学   36篇
临床医学   139篇
内科学   165篇
皮肤病学   20篇
神经病学   178篇
特种医学   66篇
外科学   202篇
综合类   3篇
预防医学   79篇
眼科学   13篇
药学   81篇
中国医学   5篇
肿瘤学   43篇
  2022年   7篇
  2021年   20篇
  2020年   10篇
  2019年   11篇
  2018年   20篇
  2017年   7篇
  2016年   21篇
  2015年   9篇
  2014年   31篇
  2013年   40篇
  2012年   52篇
  2011年   50篇
  2010年   26篇
  2009年   39篇
  2008年   58篇
  2007年   56篇
  2006年   59篇
  2005年   54篇
  2004年   30篇
  2003年   50篇
  2002年   53篇
  2001年   34篇
  2000年   42篇
  1999年   44篇
  1998年   17篇
  1997年   18篇
  1996年   16篇
  1995年   12篇
  1992年   22篇
  1991年   27篇
  1990年   35篇
  1989年   23篇
  1988年   25篇
  1987年   21篇
  1986年   10篇
  1985年   20篇
  1984年   14篇
  1982年   9篇
  1981年   7篇
  1980年   7篇
  1979年   18篇
  1978年   13篇
  1977年   16篇
  1975年   9篇
  1974年   13篇
  1973年   16篇
  1972年   12篇
  1971年   12篇
  1969年   9篇
  1964年   7篇
排序方式: 共有1354条查询结果,搜索用时 15 毫秒
21.
The value of serum creatine kinase B subunit activity (CK B) in the diagnosis of acute myocardial infarction was studied in 238 consecutive cases. All were admitted to a coronary care unit because of suspected acute myocardial infarction. Serum CK B activity was determined by an immunoinhibition procedure, using a CK M subunit inhibiting antibody (anti-M). For the evaluation of serum CK B, patients were classified into acute myocardial infarction and non-acute myocardial infarction groups. This classification was based on electrocardiographic findings, on quantitative determinations of serum aspartate aminotransferase (AST), alanine aminotransferase (ALT), and total serum creatine kinase (CK) activities, and on qualitative electrophoretic determinations of serum CK and serum lactate dehydrogenase (LD) isoenzymes. The prevalence of acute myocardial infarction in the patient material was 0.47. Serum CK B subunit activity was found to be a highly selective indicator of acute myocardial infarction with a predictive value of a positive test result of 0.97 and a predictive value of a negative test result of 0.99. The serum CK B activity increased above the acute myocardial infarction discrimination limit within 12 hours from onset of symptoms. Two non-acute myocardial infarction patients, who were resuscitated after cardiac arrest, had increased serum CK B values caused by the transient presence of CK isoenzyme BB in serum.  相似文献   
22.
An 18-year-old long-term Norwegian resident of Somali origin was submitted to hospital with bloody diarrhoea, fever, weight loss and abdominal pain. On initial colonoscopy, colitis with segmental appearance was seen. Apart from a single polymerase chain reaction (PCR) from gastric aspirate staining, PCR and culture for acid-fast bacilli revealed negative results from the multiple samples taken including sputum, gastric fluid, stool, urine and intestinal mucosa. On physical examination and CT scan, there was no evidence of ascites, lymph node enlargement or pathologic pulmonary findings. Although the diagnosis was uncertain, tuberculostatic therapy was initiated. As the conformational testing of the PCR and the microbiological work-up remained negative and the patient's condition did not improve, tuberculostatic treatment was stopped and Crohn's disease was stated as the most likely diagnosis. Although the patient improved clinically under therapy with prednisolone, newly appearing fistulas deriving from the ascending colon were noted on follow-up. Thus tuberculostatic treatment was restarted. However, signs of an acute abdomen appeared and laparotomy was performed, thereby revealing a peritoneal spread of nodules. Resection of the ileum and ascending colon was performed. Diagnosis of intestinal tuberculosis with peritoneal spread was made by histology from resected bowel specimens showing caseating granulomas and a positive PCR result. The patient's condition improved after resection of the highly inflamed bowel segments and tuberculostatic therapy. Our case report shows the difficulty of proving intestinal tuberculosis by microbiological testing, macroscopic features on colonoscopy, histology, imaging such as CT scan and by empirical therapy. Therefore, in cases of colonic inflammation, where intestinal tuberculosis is an important differential diagnosis, a more aggressive diagnostic approach such as explorative laparoscopy should be considered.  相似文献   
23.
24.
25.
26.

Purpose

Recently, there has been concern that the Copeland resurfacing humeral head implant (RHHI) leaves the shoulder joint overstuffed. The purpose of this study was in a selected cohort of patients operated with a Copeland RHHI (1) to evaluate the Length of the Gleno-Humeral Offset (LGHO), (2) to assess the patient-reported quality of life and functional outcome measured by Western Ontario Osteoarthritis of the Shoulder Index (WOOS) and (3) to determine the number of revisions in the cohort.

Methods

Pre- and postoperative radiographs were retrieved from 71 of 91 possible patients operated with a Copeland RHHI from 2005 to 2009. The cohort consisted of 30 males and 41 females at a mean age of 61 (38–89) years. One radiologist measured the LGHO and performed double measurements. The WOOS score 1 year after surgery and the number of revisions from all patients operated with a Copeland RHHI in Denmark was requested from the Danish Shoulder Arthroplasty Registry.

Results

The mean LGHO was 4.99 ± 0.53 cm before surgery and 5.39 ± 0.58 cm after surgery, (p < 0.001). 95 % limits of agreement for measurements of LGHO were ± 0.11 cm. One year after surgery, the WOOS score was 67 for the cohort and 64 for all patients operated with a Copeland RHHI in Denmark. 13 of 71 RHHI in the cohort were revised.

Conclusion

The Copeland RHHI causes significantly increased LGHO and leads to overstuffing in the shoulder joint. The WOOS score in the cohort was comparable to that for all other Danish patients operated with a Copeland RHHI.  相似文献   
27.

Background

The arthroscopically assisted Double-TightRope technique has recently been reported to yield good to excellent clinical results in the treatment of acute, high-grade acromioclavicular dislocation. However, the orientation of the transclavicular–transcoracoidal drill holes remains a matter of debate.

Hypothesis

A V-shaped drill hole orientation leads to better clinical and radiologic results and provides a higher vertical and horizontal stability compared to parallel drill hole placement.

Study design

This was a cohort study; level of evidence, 2b.

Methods

Two groups of patients with acute high-grade acromioclavicular joint instability (Rockwood type V) were included in this prospective, non-randomized cohort study. 15 patients (1 female/14 male) with a mean age of 37.7 (18–66) years were treated with a Double-TightRope technique using a V-shaped orientation of the drill holes (group 1). 13 patients (1 female/12 male) with a mean age of 40.9 (21–59) years were treated with a Double-TightRope technique with a parallel drill hole placement (group 2). After 2 years, the final evaluation consisted of a complete physical examination of both shoulders, evaluation of the Subjective Shoulder Value (SSV), Constant Score (CS), Taft Score (TF) and Acromioclavicular Joint Instability Score (ACJI) as well as a radiologic examination including bilateral anteroposterior stress views and bilateral Alexander views.

Results

After a mean follow-up of 2 years, all patients were free of shoulder pain at rest and during daily activities. Range of motion did not differ significantly between both groups (p > 0.05). Patients in group 1 reached on average 92.4 points in the CS, 96.2 % in the SSV, 10.5 points in the TF and 75.9 points in the ACJI. Patients in group 2 scored 90.5 points in the CS, 93.9 % in the SSV, 10.5 points in the TF and 84.5 points in the ACJI (p > 0.05). Radiographically, the coracoclavicular distance was found to be 13.9 mm (group 1) and 13.4 mm (group 2) on the affected side and 9.3 mm (group 1) and 9.4 mm (group 2) on the contralateral side. The distance of neither the affected side nor the contralateral side differed significantly between both groups (p > 0.05). In group 1, eight patients (53 %) and in group 2 four patients (31 %) revealed signs of dynamic posterior instability (p > 0.05). Clavicular drill hole enlargement was found to be equally distributed in group 1, whereas group 2 displayed a cone-shaped form.

Conclusion

The Double-TightRope technique yields good to excellent clinical results in both V-shaped and parallel drill hole placement. Partial recurrent vertical and horizontal instability represents a problem in both techniques. So far, no significant differences regarding clinical or radiologic results have been found. Long-term results are needed to reveal possible advantages in terms of clinical and radiologic acromioclavicular stability.  相似文献   
28.
29.
Extracellular L-glutamate poses a severe excitotoxic threat to neurons and glia when unregulated, therefore low synaptic levels of this neurotransmitter must be maintained via a rapid and robust transport system. A recent study from our laboratory showed a reduced glutamate uptake rate in the striatum of the aged Fischer 344 (F344) rat, yet the mechanism underlying this phenomenon is unknown. The current study utilized in vivo electrochemical recordings, immunoblotting and biotinylation in young (6 months), late-middle aged (18 months) and aged (24 months) F344 rats to elucidate the potential role that glutamate transporters (GLT-1, GLAST, and EAAC1) may play in this mechanism. Here we show that the time necessary to clear glutamate from the late-middle aged and aged striatum is significantly prolonged in comparison to the young striatum. In addition, an analysis of various sub-regions of the striatum revealed a marked dorsoventral gradient in terms of glutamate clearance times in the aged striatum, a phenomenon which was not present in the striatum of the animals of the remaining age groups. We also found that the decreased glutamate clearance time observed in the late-middle aged and aged rats is not due to a decrease in the production of total transporter protein among these three transporters. Rather, a significant reduction in the amount of GLAST expressed on the plasma membrane surface in the aged animals (approximately 55% when compared to young rats) may contribute to this phenomenon. These age-related alterations in extracellular l-glutamate regulation may be key contributors to the increased susceptibility of the aged brain to excitotoxic insults such as stroke and hypoxia.  相似文献   
30.
OBJECTIVE: To identify factors that influence the association between parent and child distress among families of children with cancer and comparison peers. METHODS: Parent and child distress, social support, and family environment were assessed among families of 95 children with cancer (94 mothers, 67 fathers) and 98 comparison peers (97 mothers, 77 fathers). RESULTS: Significant associations were found between parent and child distress. For models examining the impact of fathers' distress on children, several moderators were identified (i.e., family environment, child age and gender, a cancer diagnosis, and treatment severity). Family environment also partially mediated father and child distress. CONCLUSIONS: Children whose parents were distressed were more likely to be distressed themselves. Subgroups of children were particularly vulnerable, indicating a need to identify further mechanisms of risk and resilience and to develop family-based interventions. Support was found for including fathers as independent sources of information in pediatric psychology research and clinical practice.  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