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   1780篇
  免费   114篇
  国内免费   10篇
耳鼻咽喉   16篇
儿科学   45篇
妇产科学   21篇
基础医学   175篇
口腔科学   117篇
临床医学   96篇
内科学   474篇
皮肤病学   23篇
神经病学   100篇
特种医学   113篇
外科学   301篇
综合类   5篇
一般理论   1篇
预防医学   63篇
眼科学   87篇
药学   73篇
肿瘤学   194篇
  2023年   15篇
  2022年   24篇
  2021年   51篇
  2020年   32篇
  2019年   48篇
  2018年   71篇
  2017年   40篇
  2016年   42篇
  2015年   58篇
  2014年   81篇
  2013年   68篇
  2012年   118篇
  2011年   116篇
  2010年   65篇
  2009年   80篇
  2008年   106篇
  2007年   106篇
  2006年   103篇
  2005年   102篇
  2004年   107篇
  2003年   103篇
  2002年   105篇
  2001年   21篇
  2000年   13篇
  1999年   21篇
  1998年   17篇
  1997年   19篇
  1996年   16篇
  1995年   16篇
  1994年   19篇
  1993年   8篇
  1992年   8篇
  1991年   7篇
  1990年   6篇
  1989年   6篇
  1988年   4篇
  1987年   3篇
  1986年   5篇
  1984年   10篇
  1983年   11篇
  1982年   7篇
  1981年   3篇
  1980年   3篇
  1979年   4篇
  1977年   5篇
  1976年   3篇
  1965年   2篇
  1961年   2篇
  1908年   2篇
  1907年   2篇
排序方式: 共有1904条查询结果,搜索用时 46 毫秒
71.
72.
73.
74.
MR angiography of the carotid arteries: parameters affecting image quality   总被引:1,自引:0,他引:1  
RATIONALE AND OBJECTIVES: This study was performed to evaluate the relationship between dose levels of contrast medium and image quality in magnetic resonance (MR) angiography of the carotid arteries with fluoroscopically monitored, manually triggered, elliptically ordered image acquisitions. MATERIALS AND METHODS: Twenty-five patients with clinical indications for angiography of the carotid arteries were examined with MR at 1.5 T by using a fluoroscopically monitored, manually triggered, elliptically ordered pulse sequence with the administration of one of three different volumes of gadolinium-based contrast medium. The signal intensities of the vessel lumen and the surrounding tissues were measured in single partitions at the origin of the common carotid artery, the carotid bifurcation, and the intracranial internal carotid arteries. The contrast-to-noise ratio in these regions of interest also was measured. Maximum intensity projection image quality was appraised for blurring, artifacts, venous enhancement, background suppression, and contrast medium distribution. RESULTS: No artifacts or venous enhancement was observed. The position of the fluoroscopic section affected the distribution of contrast medium along the vessel, as evidenced by the difference between the contrast-to-noise ratio at the origin of the common carotid artery and the ratio at the carotid bifurcation and the intracranial internal carotid arteries (P < .01). The contrast medium dose administered was strongly correlated with image quality (r = 0.90). CONCLUSION: Contrast medium dose is related to image quality in MR angiography of the carotid arteries performed with elliptical ordering, fluoroscopic monitoring, and manual triggering.  相似文献   
75.
BACKGROUND: Giant myomas of the uterus are uncommon, particularly in developed countries. CASE: This report illustrates a case of a woman with a bilobated giant myoma of the uterus weighed in total 27.7 kg. The patient had an abdominal distension first noted 18 months before and the personal history evidenced difficulties in walking and tiredness. Abdominal hysterectomy and bilateral salpingo-oophorectomy were carried out. CONCLUSIONS: The knowledge of the different clinical manifestation of these myomas may allow to face that with adequate perioperative care, in order to assure a carefully and successfully surgery, although sometimes a benign pathology may be not easy to suspect in a first time.  相似文献   
76.
77.
Background: After open or laparoscopic Roux-en-Y gastric bypass (RYGBP) for morbid obesity, the bypassed stomach and duodenum are not readily available for radiological and endoscopic evaluation. Furthermore, little is known about the long-term physiologic and histologic changes that occur in the bypassed GI segments following these procedures. Many alternative radiological and endoscopic techniques have been described to access the distal gastric pouch and the duodenum after RYGBP. Apart from percutaneous gastrografin? studies, all these techniques require the insertion of a gastrostomy tube in the distal stomach. Methods: a new diagnostic method to access the bypassed segments by virtual CT gastroscopy (VG) was used in 5 morbidly obese patients who underwent laparoscopic RYGBP (LRYGBP). Results: All patients tolerated the procedure well, which appears safe and suitable for an outpatient setting.The virtual images offered an excellent intraluminal view of the stomach and duodenum. Conclusions: VG holds promise as the method of choice in the follow-up of LRYGB patients, having the potential to detect inflammatory changes and cancer in the excluded segments early.  相似文献   
78.
Study ObjectiveTo investigate whether diabetes, hypertension (HTN), and obesity can be considered risk factors for endometrial polyps (EPs) independently of age and menopausal status.DesignRetrospective analysis (Canadian Task Force classification III).SettingDepartment of Obstetrics and Gynecology of the University of Foggia, Italy.PatientsA total of 353 Caucasian women undergoing office hysteroscopy to assess abnormal uterine bleeding, infertility, cervical polyps, and abnormal sonographic patterns.InterventionsDemographic characteristics and data on diabetes, HTN, and menopausal status were collected and anthropometric parameters were analyzed. Vaginoscopic hysteroscopy was performed with a 5-mm continuous-flow operative office hysteroscope. When present, EPs were treated during the same procedure by means of 5-Fr scissors or electrode.Measurements and Main ResultsIn 134 (38%) of 353 cases, EPs were found. Univariable and multivariable analysis were performed to verify the presence of a statistically significant association among age, menopause, HTN, obesity, diabetes (independent variables), and the presence of EPs. Univariable logistic analysis showed a statistically significant association among age, menopause, HTN, obesity, and the presence of EPs. However, when multivariable logistic regression was performed, all the independent variables, except age, lost statistical significance (OR 1.05, 95% CI 1.02–1.07, p <.001).ConclusionAlthough it appears that EP is a disorder of aging, the significance of diabetes, HTN, and obesity, as well as menopause, on the development of EPs should be reconsidered.  相似文献   
79.
80.
Gastric carcinoma is one of the most frequent malignancies in the world and its clinical behavior especially depends on the metastatic potential of the tumor.In particular,lymphatic metastasis is one of the main predictors of tumor recurrence and survival,and current pathological staging systems reflect the concept that lymphatic spread is the most relevant prognostic factor in patients undergoing curative resection.This is compounded by the observation that two-thirds of gastric cancer in the Western world...  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