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   23548篇
  免费   1604篇
  国内免费   83篇
耳鼻咽喉   257篇
儿科学   1556篇
妇产科学   449篇
基础医学   3287篇
口腔科学   499篇
临床医学   2629篇
内科学   4560篇
皮肤病学   422篇
神经病学   1980篇
特种医学   761篇
外国民族医学   18篇
外科学   3284篇
综合类   492篇
一般理论   25篇
预防医学   1854篇
眼科学   341篇
药学   1317篇
中国医学   45篇
肿瘤学   1459篇
  2023年   110篇
  2022年   145篇
  2021年   312篇
  2020年   249篇
  2019年   419篇
  2018年   665篇
  2017年   509篇
  2016年   532篇
  2015年   455篇
  2014年   612篇
  2013年   818篇
  2012年   1471篇
  2011年   3151篇
  2010年   1414篇
  2009年   936篇
  2008年   1213篇
  2007年   1250篇
  2006年   1086篇
  2005年   1126篇
  2004年   992篇
  2003年   916篇
  2002年   795篇
  2001年   510篇
  2000年   534篇
  1999年   463篇
  1998年   243篇
  1997年   203篇
  1996年   195篇
  1995年   188篇
  1994年   161篇
  1993年   141篇
  1992年   294篇
  1991年   283篇
  1990年   245篇
  1989年   258篇
  1988年   200篇
  1987年   197篇
  1986年   190篇
  1985年   181篇
  1984年   153篇
  1983年   119篇
  1982年   79篇
  1981年   69篇
  1979年   97篇
  1978年   62篇
  1976年   66篇
  1975年   67篇
  1974年   74篇
  1973年   62篇
  1972年   75篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
32.
Cardiac ultrasound and upper gastrointestinal endoscopy are relatively old technologies. With the introduction of new ultrasound probes and by incorporating ultrasound technology into conventional endoscopes, ‘new tricks’ in cardiac imaging were discovered. Posterior structures of the heart are now able to be imaged clearly by the ultrasound probe from the oesophagus. Consequently, better resolution of cardiac anatomy allows more accurate diagnosis of cardiac pathologies which is not possible using conventional transthoracic (TT) approach. Over a period of two years, 1200 cases of transoesophageal echocardiography (TOE) were undertaken in our institution. The major indications were diseases of the aorta (10%), source of cardioembolism (28%), assessment of native and prosthetic valve function (20%), suspected endocarditis and its complication (17%), pre and post percutaneous transluminal mitral valvotomy (PTMV [13%], congenital heart disease (2%) and others (10%). The greatest impact with TOE is in the diagnosis of aortic dissection and transection, TOE is superior to conventional TT approach in detecting potential source of embolism, valvular vegetations and its complication, native and prosthetic valve dysfunction and LA thrombus prior to PTMV. Observations by TOE such as spontaneous echo contrast (SEC) in the left atrium open new challenges for further research in its role in the pathogenesis of LA thrombus and its association with cardioembolic event. Other areas of interest include; reclassification of distal aortic dissection and the use of TOE in intra-operative work.  相似文献   
33.
A case of a giant right atrial diverticulum associated with neonatal supraventricular tachycardia is reported. The electrocardiogram in sinus rhythm showed pre-excitation that may have been caused by the right atrial diverticulum adhering to the right ventricle.  相似文献   
34.
35.
Symptoms of pancreatic cancer   总被引:3,自引:1,他引:2  
We describe the symptoms, physical findings, treatment interventions, risk factors, and length of survival in persons with pancreatic cancer referred to a palliative care service (PCS) in a tertiary care facility. Data were collected prospectively over a 2-yr period using a standard clinical assessment tool in 39 patients with unresectable pancreatic cancer. Common symptoms include pain (82%), anorexia (64%), early satiety (62%), xerostomia and sleep problems (both 54%), and weight loss (51%). Analyzed retrospectively, 82% had at least one known risk factor for the development of pancreatic cancer. Twenty-five people presented to the PCS within 1 mo of diagnosis; in this group, length of survival was analyzed according to the presence of specific symptoms, and a significant inverse relationship between the presence of dyspnea and length of survival was found. As there is no effective treatment for surgically unresectable pancreatic cancer, palliation of common symptoms should be the primary emphasis of therapy.  相似文献   
36.
We introduce an image processing method which reduces white noise and random artifacts in sets of high resolution, time resolved images. At each pixel, the processing consists of: (1) the isolation of a time intensity curve (TIC), (2) Fourier transformation of each TIC, (3) application of a threshold to remove low intensity coefficients, (4) inverse transformation to generate noise reduced TICS which are recombined to form images with improved signal-to-noise ratio (SNR). Noise filtering by Fourier thresholding is demonstrated on a set of cardiac images, resulting in a reduction of the noise energy by approximately 90%.  相似文献   
37.
Respiratory syncytial virus (RSV) infection has been shown to induce human mononuclear leukocyte (MNL) production of net interleukin-1 (IL-1)-inhibitor activity. In the current studies of IL-1-inhibitor effects, RSV-exposed cells were compared with autologous MNL that were sham-exposed or exposed to inactivated RSV or influenza virus (which induces net IL-1 activity and commonly elicits effective homotypic immunity). Exposure of MNL to influenza virus or inactivated RSV resulted in increased expression of human leukocyte antigen-DR, the IL-2 receptor, and the transferrin receptor and increased progression through the cell cycle by 3 days. In contrast, exposure to infectious RSV resulted in decreased marker expression and cell cycle arrest, with abrogation of proliferation in response to the virus or other stimuli. These data raise the possibility that a contributing mechanism for recurrence of RSV infection is early suppression of the clonal expansion of virus-specific lymphocytes due to net IL-1-inhibitor activity.  相似文献   
38.
Summary Sections of formalin-fixed, paraffin-blocked tissue from 116 primary transitional cell carcinomas were stained immunohistochemically using a polyclonal antibody against the c-erbB-2 oncoprotein. Positive staining of cell membranes, known to correlate with gene amplification, was seen in 22 (19%) of the 116, with variable staining from tumour to tumour and within tumours themselves. Consistent with its mooted value as a prognosticator in bladder cancer, the c-erbB-2 oncoprotein was detected in 13 (of 40) grade III and 9 of the 26 muscle-invasive tumours examined compared to 1 (of 25) grade I and 6 (of 66) mucosa only (pTa) lesions. These results support further examination of c-erbB-2 expression in bladder cancer.  相似文献   
39.
40.
Background Significant tumor downstaging has been achieved in patients with localized gastric or gastroesophageal adenocarcinoma by induction chemotherapy and preoperative chemoradiotherapy (CTX–CTXRT). However, the influence of CTX–CTXRT on operative morbidity and mortality has not yet been clarified. The aim of the present study was to document the frequency and nature of morbidity and mortality after surgery combined with CTX–CTXRT, and identify factors predictive of postoperative complications in patients with localized gastric or gastroesophageal adenocarcinoma. Methods A prospectively collected database on 71 consecutive patients who underwent CTX–CTXRT at M.D. Anderson Cancer Center between January 1997 and August 2004 was reviewed. Postoperative morbidity and mortality were investigated, and risk factors for overall complications were identified by multivariate logistic regression analysis. Results Overall morbidity and mortality rates were 38.0% (27 patients) and 2.8% (2 patients), respectively. Age greater than 60 years [relative risk 11.3 (95% confidence interval 2.50–50.6)] and body mass index (BMI) of 26 kg/m2 or above [relative risk 4.08 (95% confidence interval 1.08–15.4)] were significant risk factors for overall complications. Conclusions CTX–CTXRT can be performed safely with an acceptable operative morbidity and a low operative mortality rate in patients with gastric or gastroesophageal cancer, with careful consideration of added risk associated with age and obesity.  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