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   26952篇
  免费   1335篇
  国内免费   253篇
耳鼻咽喉   225篇
儿科学   529篇
妇产科学   632篇
基础医学   2852篇
口腔科学   562篇
临床医学   2347篇
内科学   7806篇
皮肤病学   572篇
神经病学   2381篇
特种医学   935篇
外科学   4352篇
综合类   63篇
一般理论   5篇
预防医学   1018篇
眼科学   346篇
药学   1427篇
中国医学   46篇
肿瘤学   2442篇
  2024年   27篇
  2023年   226篇
  2022年   463篇
  2021年   781篇
  2020年   497篇
  2019年   644篇
  2018年   769篇
  2017年   591篇
  2016年   731篇
  2015年   796篇
  2014年   1015篇
  2013年   1394篇
  2012年   2174篇
  2011年   2112篇
  2010年   1241篇
  2009年   1111篇
  2008年   1935篇
  2007年   1826篇
  2006年   1666篇
  2005年   1682篇
  2004年   1541篇
  2003年   1364篇
  2002年   1260篇
  2001年   180篇
  2000年   125篇
  1999年   174篇
  1998年   222篇
  1997年   205篇
  1996年   158篇
  1995年   187篇
  1994年   152篇
  1993年   141篇
  1992年   97篇
  1991年   84篇
  1990年   102篇
  1989年   65篇
  1988年   52篇
  1987年   53篇
  1986年   67篇
  1985年   65篇
  1984年   68篇
  1983年   45篇
  1982年   55篇
  1981年   38篇
  1980年   48篇
  1979年   38篇
  1977年   22篇
  1975年   24篇
  1974年   34篇
  1973年   22篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
61.
BACKGROUND: We have noted an unexpectedly high incidence of prostate cancer in our heart transplant recipients (HTR). METHODS: We conducted a retrospective review of patients after heart transplantation to investigate the prevalence, treatment, and outcome of prostate cancer diagnosed after systematic screening (study group). We compared them with case-matched HTR (control). RESULTS: Among 702 recipients, 15 patients had elevated prostate-specific antigen (PSA) levels. Fourteen cases of prostate cancer were diagnosed and treated. The median time between transplantation and prostate cancer diagnosis was 73 months. No patient was diagnosed in a locally advanced (>T2) or metastatic stage. Eleven patients (78.6%) received curative treatment. During follow-up (median, 44 months), 1 patient died from prostate cancer. The survival rate between the study and control groups did not differ. CONCLUSION: Routine PSA testing is recommended as a screening test for prostate cancer in patients after heart transplantation. We believe this could also result in detection of early stages of prostate cancer, thus allowing curative treatment, and achieving similar survival to other case-matched HTR with no prostate cancer.  相似文献   
62.
Embryonic remnants of incomplete septation may complicate occlusiondevice implantation in secundum atrial septal defects (sASD)even if stiff devices such as the Amplatzer Occluder are used. A 35-year-old woman was referred to our center for evaluationof a sASD.  相似文献   
63.
Bisphosphonate-related osteonecrosis of the jaws (BRONJ) is mainly observed in patients with multiple myeloma and bone metastasis from solid tumors receiving iv bisphosphonate therapy. The reported incidence of BRONJ is significantly higher with the iv preparations zoledronic acid and pamidronate while the risk appears to be minimal for patients receiving oral bisphosphonates. Currently available published incidence data for BRONJ are based on retrospective studies and estimates of cumulative incidence range from 0.8 to 12%. The mandible is more commonly affected than the maxilla (2:1 ratio), and 60–70% of cases are preceded by a dental surgical procedure. The signs and symptoms that may occur before the appearance of clinical evident osteonecrosis include changes in the health of periodontal tissues, non-healing mucosal ulcers, loose teeth and unexplained soft-tissue infection. Although the definitive role of bisphosphonates remains to be elucidated, the inhibition of physiologic bone remodeling and angiogenesis by these potent drugs impairs the regenerative capacity of the bone causing the development of BRONJ. Tooth extraction as a precipitating event is a common observation. The significant benefits that bisphosphonates offer to patients clearly surpass the risk of potential side effects; however, any patient for whom prolonged bisphosphonate therapy is indicated, should be provided with preventive dental care in order to minimize the risk of developing this severe condition. This article provides an update review of current knowledge about clinical, pathological and management aspects of BRONJ.  相似文献   
64.
Malignant myoepitheliomas are rare tumors of salivary glands. Most occur in the parotid gland; few other sites of origin are described. Malignant myoepithelioma of the rhinopharynx has only been reported twice. Because the lesion is so rare, there are no specific indications for its treatment. We present a third case of malignant myoepithelioma in the rhinopharynx and discuss its diagnostic and therapeutic aspects.  相似文献   
65.
Brain activation maps of blood oxygenation level dependent (BOLD) signals during functional magnetic resonance imaging (fMRI) are sensitive to unwanted contributions from large vessels. Most BOLD-fMRI studies are based on a stimulus-correlated modulation of the MRI signal amplitude that is sensitive to desired microvascular effects and unwanted macrovascular effects. Aiming to suppress macrovascular effects in activation patterns, this BOLD-fMRI study evaluates brain activation during a verbal working memory task (2-back) in healthy volunteers (n=18) using the amplitude and phase components of the MRI signal. The use of the first time point as a phase reference allowed us to eliminate phase wrapping artifacts and increase the statistical power of 'phase' activation, and this information was used to filter out voxels with significant macrovascular (i.e., draining and pial veins) contribution in 'amplitude' activation patterns. Across subjects, the task produced large modulations of the relative phase in the occipital, dorsolateral prefrontal, and parietal cortices, suggesting a common distribution of draining veins in these regions across subjects, and in the rostral frontal cortex, probably associated to stimulus-correlated motion of the head. The phase filtering method partially suppressed BOLD responses in the superior and lateral prefrontal, parietal, and occipital cortices; therefore the commonly reported brain activation in these cortices during working memory tasks may include significant macrovascular contributions. This study suggests that the phase information embedded in the MRI signal can be used to suppress unwanted macrovascular contributions in fMRI studies.  相似文献   
66.
Objective: Endothelial dysfunction represents a critical early component of organ injury following cardiopulmonary bypass. Recent studies demonstrate that the treatment with atorvastatin is associated with a significant improvement of endothelial function independently of its efficacy on cholesterol levels. Therefore, we investigated the effects of preoperative atorvastatin treatment on endothelium function after coronary surgery. Methods: Forty patients undergoing coronary surgery were randomized to treatment with atorvastatin (20 mg/die; N = 20) or placebo (N = 20) 3 weeks before surgery. Twenty normal patients served as control group. The flow-mediated dilations (FMD) of the brachial artery after both reactive hyperemia (endothelium dependent) and nitroglycerin administration (endothelium independent) were evaluated at baseline, at 48 h, and 5 days postoperatively. Results: At baseline, the endothelium-dependent FMD was significantly attenuated in coronary versus normal patients (normal 10.3 ± 1.8% vs coronary 4.1 ± 1.6%, p < 0.01). At 48 h postoperatively all patients exhibited a reduced FMD compared with baseline values: the endothelium-dependent dilatation showed a drop of 60.1 + 15% in the patients of the placebo group compared with 45.8 + 16.6% (p < 0.05) those in the atorvastatin group. At the univariate analysis, no significant correlation was found between serum levels of either total cholesterol or HDL cholesterol and FMD. The nitroglycerin-induced dilation was not significantly influenced by extracorporeal circulation as well as by atorvastatin treatment. Conclusions: The endothelial dysfunction following cardiopulmonary bypass is improved by the treatment with atorvastatin, by a mechanism unrelated to the drug efficacy of controlling serum cholesterol levels.  相似文献   
67.
68.
We describe a patient with neonatal Marfan syndrome presenting with massive ascending and descending thoracic aortic aneurysm. Because of rapidly progressive respiratory distress due to tracheobronchial compression, emergency replacement of the descending thoracic aorta with a 12-mm PTFE vascular prosthesis was undertaken at 1 month of age. The postoperative course was complicated by bilateral tension pneumothorax contributing to irreversible respiratory failure. The unique clinico-pathological features and the relevant surgical implications of the case are discussed. (J Card Surg 1994;9:109–114)  相似文献   
69.
Summary: IgAN is the commonest primary glomerulonephritis in all parts of the world; the different incidence reported in different geographical areas is mainly due to different biopsy policies, even though genetic factors, still unclarified, may be acting. Progression to ESRF occurs in IgAN at a variable rate (average renal survival at 10 years is 80–87%), and many studies, reviewed in this paper, have sought to identify clinical and histological features which are predictive of the outcome. A functional impairment at presentation and a severe proteinuria are the most powerful clinical indicators of unfavourable prognosis, while both glomerular and interstitial sclerosis are the most reliable histological indicators. The fact that these prognostic indicators are not always reliable in predicting the outcome for a single patient, probably due to the pathophysiology of the progressive damage in this disease, is stressed.  相似文献   
70.
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