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   937篇
  免费   68篇
  国内免费   4篇
耳鼻咽喉   3篇
儿科学   56篇
妇产科学   20篇
基础医学   139篇
口腔科学   29篇
临床医学   69篇
内科学   166篇
皮肤病学   30篇
神经病学   44篇
特种医学   147篇
外国民族医学   1篇
外科学   75篇
综合类   64篇
预防医学   50篇
眼科学   9篇
药学   24篇
中国医学   4篇
肿瘤学   79篇
  2021年   12篇
  2020年   7篇
  2019年   9篇
  2018年   14篇
  2017年   17篇
  2016年   17篇
  2015年   15篇
  2014年   22篇
  2013年   35篇
  2012年   37篇
  2011年   27篇
  2010年   59篇
  2009年   48篇
  2008年   35篇
  2007年   30篇
  2006年   22篇
  2005年   15篇
  2004年   13篇
  2003年   11篇
  2002年   15篇
  2001年   20篇
  2000年   18篇
  1999年   18篇
  1998年   37篇
  1997年   38篇
  1996年   37篇
  1995年   37篇
  1994年   24篇
  1993年   21篇
  1992年   13篇
  1991年   11篇
  1990年   11篇
  1989年   20篇
  1988年   26篇
  1987年   20篇
  1986年   20篇
  1985年   15篇
  1984年   21篇
  1983年   19篇
  1982年   18篇
  1981年   14篇
  1980年   16篇
  1979年   8篇
  1978年   11篇
  1976年   8篇
  1975年   6篇
  1974年   5篇
  1972年   4篇
  1971年   4篇
  1967年   5篇
排序方式: 共有1009条查询结果,搜索用时 15 毫秒
11.
Interstitial chromosomal deletions at 22q11.2 and 7q11.23 are detected in the vast majority of patients affected by CATCH 22 syndromes and the Williams-Beuren syndrome, respectively. In a group of 15 Williams- Beuren patients, we have shown previously that a large number of 7q11.23 deletions occur in association with an interchromosomal rearrangement, indicative of an unequal crossing-over event between the two homologous chromosomes 7. In this study, we show that a similar mechanism also underlies the formation of the 22q11.2 deletions associated with CATCH 22. In eight out of 10 families with a proband affected by CATCH 22, we were able to show that a meiotic recombination had occurred at the critical deleted region based on segregation analysis of grandparental haplotypes. The incidences of crossovers observed between the closest informative markers, proximal and distal to the deletion, were compared with the expected recombination frequencies between the markers. A significant number of recombination events occur at the breakpoint of deletions in CATCH 22 patients (P = 2.99x10(-7)). The segregation analysis of haplotypes in three- generation families was also performed on an extended number of Williams-Beuren cases (22 cases in all). The statistically significant occurrence of meiotic crossovers (P = 4.45x10(-9)) further supports the previous findings. Thus, unequal meiotic crossover events appear to play a relevant role in the formation of the two interstitial deletions. The recurrence risk for healthy parents in cases where such meiotic recombinations can be demonstrated is probably negligible. Such a finding is in agreement with the predominantly sporadic occurrence of the 22q11.2 and 7q11. 23 deletions. No parent-of-origin bias was observed in the two groups of patients with regard to the origin of the deletion and to the occurrence of inter- versus intrachromosomal rearrangements.   相似文献   
12.
The present study compared the accuracy of ventilation perfusion scintigraphy (VQS) and CT pulmonary angiography (CTPA) for the diagnosis of pulmonary embolism. This was a prospective observational study of 112 patients with suspected pulmonary embolism (PE) who could be studied with both investigations within 24 h. Results were compared to final diagnosis at completion of 6-month follow up, using receiver operating characteristic (ROC) analysis. Pulmonary embolism was diagnosed in 27 referred patients (24%). The sensitivity and specificity of VQS and CTPA were similar to that reported from the literature. A normal VQ scan had the highest negative predictive value (100%), while a high-probability VQ scan had the highest positive predictive value (92%). There was no overall difference (area under the ROC curve (AUC)) between VQS (AUC (95% CI) = 0.82 (0.75,0.89)) and CTPA (AUC = 0.88 (0.81,0.94)) for the diagnosis of PE. Among patients with abnormal chest X-rays, CTPA (AUC 0.90 (0.83,0.97)) appeared somewhat better than VQS (AUC 0.78 (0.68,0.88)) but this difference did not reach statistical significance. In this instance, CTPA is at least as accurate as VQS and may provide an opportunity to make alternative diagnoses.  相似文献   
13.
14.
15.
16.

Background  

Human immunodeficiency virus infected individuals are prone to malnutrition due to increased energy requirements, enteropathy and increased catabolism. Trace elements such as zinc and selenium have major role in maintaining a healthy immune system. This study was designed to evaluate the nutritional status of Iranian subjects who were newly diagnosed with human immunodeficiency virus infection and to compare serum level of zinc and selenium in these patients with those of the sex and aged match healthy subjects.  相似文献   
17.
Digestive Diseases and Sciences - Evidence is now available in support of using fecal biomarkers to monitor disease activity in inflammatory bowel disease (IBD). Patient adherence is often cited as...  相似文献   
18.
There are five common ways in which a patient may object to a physician's suggestion of a psychiatric referral. The patient may reject the referral because of the social stigma of being a psychiatric patient; because the referral damages his or her self-esteem; because the patient does not understand the role of emotions in physical discomfort; because the patient feels rejected by the referring physician; or because of the effects of psychiatric illness. Following a thorough medical workup, the physician can best discharge his or her responsibility to the patient by paying attention to these possible misunderstandings. The physician can discuss the role of social stigma, offset the blows to the patient's self-esteem, educate the patient about the psychosomatic model of disease, and assure the patient of the physician's continuing interest and involvement.  相似文献   
19.
背景目前已开展了对重性精神病患者进提供连续性服务的研究。目的探讨基层对有抑郁症风险患者提供连续性服务的水平,并与对心力衰竭患者的服务水平进行对比。方法采用抑郁症风险患者与心力衰竭患者对比的探索性研究。采用患者问卷评估服务的持续性,包含如下内容:(1)联系的服务提供者数(个人连续性);(2)诊所内服务提供者之间的合作(团队连续性)(6个项目,分数1~5分);(3)诊所外全科医师与服务提供者之间的合作(跨界连续性)(4个项目,分数1~5分)。结果大多数抑郁症风险患者在过去1年中寻遍整个服务提供界联系了几个服务提供者,曾遇到过高水平团队连续性服务及低水平跨界连续性服务。在诊所中可接触到的不同服务提供者要明显多于心力衰竭患者服务提供者(P<0.01)。抑郁症风险患者的服务提供者之间的合作更好一些,每项平均得分4.3分,心力衰竭患者得分为4.0分(P=0.03)。然而,跨界连续性服务方面正好相反:抑郁症风险患者每项平均得分3.5分,心力衰竭患者得分为4.0分(P=0.01)。结论抑郁症风险患者与心力衰竭患者之间的探索性对比显示:体验服务连续性方面的差距不大。对此还应行进一步分析。  相似文献   
20.
Thirty-four ambulatory medical patients who had used minor tranquilizers for varying lengths of time were interviewed to determine their medical and psychiatric statuses, and to learn their own perspective of their medical care. The population was elderly of lower socioeconomic status, and chronically ill (a significant minority with serious and disabling illness). Depressive equivalents, depression, and anxiety were prominent, but clinical states requiring psychiatric care were not. Slightly less than one-half were alcoholic. Forty-one percent took the medications for target symptoms other than anxiety, and 76% believed these agents were efficacious. Chronic users had significantly more chronic medical illness, and significantly more somatization, anxiety, and fatigue.  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