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   1872篇
  免费   111篇
  国内免费   12篇
耳鼻咽喉   25篇
儿科学   28篇
妇产科学   25篇
基础医学   267篇
口腔科学   28篇
临床医学   149篇
内科学   535篇
皮肤病学   37篇
神经病学   125篇
特种医学   95篇
外科学   181篇
综合类   8篇
预防医学   44篇
眼科学   59篇
药学   151篇
中国医学   4篇
肿瘤学   234篇
  2024年   3篇
  2023年   13篇
  2022年   28篇
  2021年   47篇
  2020年   37篇
  2019年   36篇
  2018年   54篇
  2017年   49篇
  2016年   54篇
  2015年   57篇
  2014年   77篇
  2013年   76篇
  2012年   132篇
  2011年   147篇
  2010年   78篇
  2009年   71篇
  2008年   108篇
  2007年   130篇
  2006年   172篇
  2005年   119篇
  2004年   123篇
  2003年   100篇
  2002年   104篇
  2001年   17篇
  2000年   11篇
  1999年   20篇
  1998年   16篇
  1997年   12篇
  1996年   15篇
  1995年   9篇
  1994年   7篇
  1993年   5篇
  1992年   10篇
  1991年   7篇
  1990年   5篇
  1989年   6篇
  1988年   5篇
  1987年   3篇
  1986年   7篇
  1985年   4篇
  1984年   3篇
  1983年   3篇
  1982年   2篇
  1977年   2篇
  1975年   1篇
  1974年   3篇
  1973年   1篇
  1972年   1篇
  1969年   2篇
  1968年   1篇
排序方式: 共有1995条查询结果,搜索用时 15 毫秒
61.
62.
Cyclin‐dependent kinase 12 (CDK12), one of the key factors associated with DNA damage response pathways, is located on chromosome 17 proximal to Erb‐B2 receptor tyrosine kinase 2 (ERBB2). In this report, CDK12 and ERBB2 coamplification was detected by targeted next‐generation sequencing in two urothelial carcinomas. The staining intensity of the CDK12 and human epidermal growth factor receptor‐2 proteins was associated with the prognosis of each urothelial carcinoma case. Our results suggest that CDK12 coamplification with ERBB2 might be associated with tumor aggressiveness and contribution to cancer pathogenesis. Therapies targeting CDK12 should be developed for these patients.  相似文献   
63.
64.
65.
Background: Previous comparative studies suggest that the requirement for Nodal in epiblast and hypoblast development is unique to mammalians. Expression of anterior visceral endoderm (AVE) genes in the visceral endoderm and of their orthologs in the hypoblast may be unique to mammalians and avians, and is absent in the reptilian hypoblast. Axis formation in reptiles is signaled by the formation of the posterior marginal epiblast (PME), which expresses a series of primitive streak genes. To assess the phylogenetic origin of Nodal and AVE gene expression and axis formation in amniotes, we examined marker gene expression in gray short‐tailed opossum, a metatherian. Results: Nodal was expressed in neither epiblast nor hypoblast of opossum embryos. No AVE genes were expressed in the opossum hypoblast. Attainment of polarity in the embryonic disk was signaled by Nodal, Wnt3a, Fgf8, and Bra expression in the PME at 8.5 days post‐coitus. Conclusions: Nodal expression in epiblast or hypoblast may be unique to eutherians. AVE gene expression in visceral endoderm and hypoblast may have been independently acquired in eutherian and avian lineages. PME formation appears to be the event that signals axis formation in reptilian and metatherian embryos, and thus may be an ancestral characteristic of basal amniotes. Developmental Dynamics 245:1176–1188, 2016. © 2016 Wiley Periodicals, Inc.  相似文献   
66.
The purpose of this study was to describe Japanese hospital nurses' perceptions of the nursing practice environment and examine its association with nurse‐reported ability to provide quality nursing care, quality of patient care, and ward morale. A cross‐sectional survey design was used including 223 nurses working in 12 acute inpatient wards in a large Japanese teaching hospital. Nurses rated their work environment favorably overall using the Japanese version of the Practice Environment Scale of the Nursing Work Index. Subscale scores indicated high perceptions of physician relations and quality of nursing management, but lower scores for staffing and resources. Ward nurse managers generally rated the practice environment more positively than staff nurses except for staffing and resources. Regression analyses found the practice environment was a significant predictor of quality of patient care and ward morale, whereas perceived ability to provide quality nursing care was most strongly associated with years of clinical experience. These findings support interventions to improve the nursing practice environment, particularly staffing and resource adequacy, to enhance quality of care and ward morale in Japan.  相似文献   
67.
Electrophysiologic studies were performed in 16 patients 11 to 45 years old (mean 33 years) with idiopathic sustained (lasting more than 5 min) ventricular tachycardia (VT) originating from the left ventricle. Endocardial mapping during VT showed that the earliest site of activation was at the apical inferior portion of the left ventricle in 14 patients whose QRS morphology during VT showed a right bundle branch block pattern and left-axis deviation, but at the apical anterosuperior portion of the left ventricle in two patients whose QRS morphology during VT showed a right bundle branch block and right-axis deviation. Single programmed ventricular stimulation induced VT in 13 patients, and rapid ventricular pacing induced VT in the remaining three patients. Rapid ventricular pacing terminated VT in all patients. The relationship between the coupling interval and the echo interval was inverse in all eight patients with a wide VT inducible zone. Entrainment was recognized in three of six patients. The initiation of VT by constant pacing depended on the number of pacing beats but not the duration of pacing in all four patients tested. Intravenous verapamil terminated the VT in 13 of 14 patients. Long-term oral verapamil was also effective in all five patients who required long-term oral therapy for their symptoms associated with VT. In conclusion (1) idiopathic left ventricular tachycardia has unique electrocardiographic, electrophysiologic, and electropharmacological properties, (2) the electrophysiologic characteristics suggest that the mechanism is reentry, and (3) verapamil is effective in both the short- and long-term treatment of VT.  相似文献   
68.
69.
Bleeding after gastric endoscopic submucosal dissection (ESD) remains problematic, especially in patients receiving antithrombotic therapy. Therefore, this study aimed to identify the risk factors. In this retrospective study, patients (n = 1,207) who underwent gastric ESD while receiving antithrombotic therapy were enrolled at Osaka Medical and Pharmaceutical University Hospital and 18 other referral hospitals in Japan. Risks of post-ESD bleeding were calculated using multivariable logistic regression. The dataset was divided into a derivation cohort and a validation cohort. We created a prediction model using the derivation cohort. The accuracy of the model was evaluated using the validation cohort. Post-ESD bleeding occurred in 142 (11.8%) participants. Multivariable analysis yielded an odds ratio of 2.33 for aspirin, 4.90 for P2Y12 receptor antagonist, 1.79 for cilostazol, 0.95 for other antithrombotic agents, 6.53 for warfarin, 5.65 for dabigatran, 7.84 for apixaban, 10.45 for edoxaban, 6.02 for rivaroxaban, and 1.46 for heparin bridging. The created prediction model was called safe ESD management using the risk analysis of post-bleeding in patients with antithrombotic therapy (SAMURAI). This model had good predictability, with a C-statistic of 0.77. In conclusion, use of the SAMURAI model will allow proactive management of post-ESD bleeding risk in patients receiving antithrombotic therapy.  相似文献   
70.
Background: Ishihara pseudoisochromatic plates are one of the best screening tools for red‐green colour vision deficiencies. Although a majority of persons with normal colour vision read all plates correctly, a significant proportion makes mistakes. The purpose of this study was to obtain results for normal trichromats reading the Ishihara plates and analyse the misreading responses to seek clinical implications. Methods: A sample of 249 (161 female) was tested with the Ishihara pseudoisochromatic plates. The number and nature of errors were recorded and typical errors, those that observers with abnormal colour vision were expected to make, were distinguished from other kinds of error. Results: Out of 249 normal trichromats, 111 individuals (45 per cent) misread at least one plate. Females made up to six total errors and males up to five total errors. When only typical errors were counted, all the normal trichromats made two or fewer errors. There was no significant gender difference for either total or typical errors. Conclusion: It is suggested that clinicians count only typical errors when administering the Ishihara test. Using a criterion of no more than two typical errors for a diagnosis of normal colour vision could improve the specificity and sensitivity of the test.  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