全文获取类型
收费全文 | 127814篇 |
免费 | 7211篇 |
国内免费 | 1098篇 |
专业分类
耳鼻咽喉 | 1954篇 |
儿科学 | 1970篇 |
妇产科学 | 1880篇 |
基础医学 | 20307篇 |
口腔科学 | 3102篇 |
临床医学 | 11928篇 |
内科学 | 22879篇 |
皮肤病学 | 3979篇 |
神经病学 | 10329篇 |
特种医学 | 7489篇 |
外科学 | 16665篇 |
综合类 | 552篇 |
现状与发展 | 3篇 |
一般理论 | 27篇 |
预防医学 | 6716篇 |
眼科学 | 3195篇 |
药学 | 11427篇 |
中国医学 | 1460篇 |
肿瘤学 | 10261篇 |
出版年
2023年 | 912篇 |
2022年 | 2716篇 |
2021年 | 4401篇 |
2020年 | 2110篇 |
2019年 | 2949篇 |
2018年 | 3695篇 |
2017年 | 2998篇 |
2016年 | 3916篇 |
2015年 | 5451篇 |
2014年 | 6460篇 |
2013年 | 7520篇 |
2012年 | 11255篇 |
2011年 | 10789篇 |
2010年 | 6198篇 |
2009年 | 5344篇 |
2008年 | 7552篇 |
2007年 | 7159篇 |
2006年 | 6474篇 |
2005年 | 5983篇 |
2004年 | 5218篇 |
2003年 | 4549篇 |
2002年 | 3912篇 |
2001年 | 3045篇 |
2000年 | 2795篇 |
1999年 | 2148篇 |
1998年 | 954篇 |
1997年 | 718篇 |
1996年 | 571篇 |
1995年 | 498篇 |
1994年 | 431篇 |
1993年 | 378篇 |
1992年 | 758篇 |
1991年 | 702篇 |
1990年 | 652篇 |
1989年 | 588篇 |
1988年 | 493篇 |
1987年 | 497篇 |
1986年 | 364篇 |
1985年 | 391篇 |
1984年 | 276篇 |
1983年 | 200篇 |
1982年 | 153篇 |
1981年 | 182篇 |
1980年 | 135篇 |
1979年 | 224篇 |
1978年 | 166篇 |
1977年 | 129篇 |
1976年 | 143篇 |
1975年 | 133篇 |
1974年 | 139篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Bone marrow edema and associated pain in early stage osteonecrosis of the femoral head: prospective study with serial MR images 总被引:31,自引:0,他引:31
PURPOSE: To determine the accuracy of magnetic resonance (MR) cholangiography for demonstration of the biliary tract and detection of biliary complications in patients who have undergone orthotopic liver transplantation. MATERIALS AND METHODS: Breath-hold half-Fourier rapid acquisition with relaxation enhancement MR cholangiography was performed in 25 patients who had undergone orthotopic liver transplantation. MR cholangiograms were prospectively and independently interpreted by two radiologists for depiction of the biliary tract and ductal anastomosis and for complications (eg, biliary dilatation, stricture, stones). MR cholangiographic findings were correlated with findings from direct cholangiography (n = 24) and surgery (n = 1). RESULTS: MR cholangiography completely demonstrated first-order intrahepatic bile ducts in 23 (92%) patients, the donor extrahepatic bile duct in 25 (100%), the recipient extrahepatic bile duct in 17 of 18 (94%), and the anastomosis in 24 (96%). The sensitivity, specificity, accuracy, positive predictive value, and negative predictive value of MR cholangiography for detection of biliary dilatation and stricture were each 100%. Complete interobserver agreement occurred in the detection of biliary dilatation and stricture. The sensitivity, specificity, accuracy, positive predictive value, and negative predictive value of MR cholangiography for detection of stones were 100% for one radiologist and 86%, 100%, 96%, 100%, and 95%, respectively, for the other. Both radiologists agreed on the diagnosis of bile duct stones in six of seven cases (kappa = 0.90). CONCLUSION: MR cholangiography enables accurate depiction of the biliary tract and detection of biliary complications in patients with an orthotopic liver transplant. 相似文献
992.
Kim MJ Park S Kim NK Kim MJ Chung JJ Outwater EK 《Journal of computer assisted tomography》1999,23(1):94-95
We report the transrectal ultrasonographic (TRUS) and endorectal surface coil MR findings for paragonimiasis involving the perirectal space. The patient presented with voiding difficulty. TRUS showed a well demarcated, oval-shaped hyperechoic mass in the perirectal space. On endorectal MR images, the lesion was depicted as a well defined cystic mass with homogeneous intermediate signal intensity on T1-weighted images and heterogeneous hyperintensity on T2-weighted images. Ectopic paragonimiasis can appear as a well defined cystic mass in the peritoneum and should be included in the differential diagnosis of cystic mass in the abdomen and pelvic cavity, including the perirectal space. 相似文献
993.
Choi D Lee KS Suh GY Kim TS Kwon OJ Rhee CH Han J 《Journal of computer assisted tomography》1999,23(1):107-113
PURPOSE: The purpose of this work was to describe the radiologic findings of pulmonary tuberculosis in patients who presented with acute respiratory failure. METHODS: We included patients who had newly diagnosed active pulmonary tuberculosis and who presented with acute respiratory failure. Initial chest radiographic (n = 17) and high-resolution CT (n = 11) findings of each patient were analyzed retrospectively. RESULTS: Of 1,010 patients with active pulmonary tuberculosis, 17 patients (1.7%) presented with acute respiratory failure. Nine (53%) of the 17 patients died. The most common initial chest radiographic findings were small nodular lesions (16/17; 94%), consolidation (13/17; 76%), and ground-glass opacity (12/17; 70%). Eleven (69%) of 16 nodular lesions, 9 of 13 (69%) consolidations, and 10 of 12 (83%) ground-glass opacities were bilateral. On HRCT (n = 11), miliary micronodular lesions were seen in 6 patients (55%), whereas bronchogenic spread of tuberculosis with disseminated centrilobular nodules and tree-in-bud appearance was seen in 5 patients (45%). Diffuse areas of ground-glass attenuation were seen in all six patients with miliary nodules and four of five patients with bronchogenic spread of tuberculosis. CONCLUSION: Patients with pulmonary tuberculosis occasionally present with acute respiratory failure. In this condition, chest radiograph most commonly shows bilateral small nodular lesions mixed with consolidation or ground-glass opacity, whereas HRCT demonstrates findings of miliary or bronchogenic disseminated tuberculosis with diffuse areas of ground-glass attenuation. 相似文献
994.
This retrospective study correlated the mammographic manifestations and averaged nuclear grades using Holland, Van-Nuys, and Lagios classifications in 37 cases of ductal carcinoma in situ (DCIS); microcalcifications alone were seen in 59.4%, microcalcifications with associated mass in 19%, and mass alone in 21.6%. DCIS is more likely to be accompanied by microcalcifications than mass on mammography. Correlation is good between the nuclear grades of DCIS and mammographic manifestations. 相似文献
995.
Qian Z Maynar M Usón-Garallo J Sanchez-Margallo F Lima-Rodriguez MA Lima-Rodrigues JR Kim JK Gonzalez-Roman A Castañeda WR 《Academic radiology》1999,6(5):317-320
RATIONALE AND OBJECTIVES: The purpose of the study was to evaluate a method of producing obstruction of the common bile duct and concomitant biliary duct dilatation in an animal model. MATERIALS AND METHODS: Laparoscopic placement of a double-balloon occlusion device was used to produce common bile duct obstruction and bile duct dilatation in pigs. RESULTS: One week after the procedure, common bile duct obstruction and dilatation of the biliary tree were demonstrated with either percutaneous transhepatic cholangiography or percutaneous cholecystography. CONCLUSION: The use of this method is technically feasible and provides a useful subacute and chronic animal model of common bile duct obstruction and dilatation of the biliary tree for percutaneous interventional training and research purposes. 相似文献
996.
997.
Kim SS Kaihara S Benvenuto MS Kim BS Mooney DJ Vacanti JP 《Journal of pediatric surgery》1999,34(1):124-128
BACKGROUND/PURPOSE: Hepatotrophic factors in the portal blood are critically important for the survival of heterotopically transplanted hepatocytes. Currently, no model exists for the implantation of hepatocytes on biodegradable polymer scaffolds with direct access to the portal blood. This study investigates the use of small intestinal submucosa (SIS) as a small-caliber venous conduit that may be used for the implantation of tissue-engineered liver. METHODS: SIS was prepared from segments of rat jejunum and implanted as a venous conduit between the portal vein and inferior vena cava in 26 heparinized Lewis rats. Venograms were performed periodically, and the grafts were harvested at various time-points and examined by scanning electron microscopy (SEM) and histology. Von Willebrand Factor (vWF) staining was performed to assess endothelialization. RESULTS: Five rats died of technical complications. Seventeen of 21 rats (81%) maintained patent grafts at the time of death up to 8 weeks. Venograms demonstrated patent grafts at 3 and 8 weeks. SEM results showed a smooth luminal surface with endothelial-like cells by 3 weeks. Histology demonstrated a confluent luminal endothelial monolayer, absence of thrombus, and neovascularization in the SIS graft. VWF staining results were positive, confirming the growth of endothelial cells on the luminal surface. In preliminary studies, implantation of hepatocytes seeded on biodegradable polymer tubes into the SIS graft demonstrated clusters of viable cells after 2 days. CONCLUSIONS: Rat SIS can be prepared readily, maintains high patency as a small-caliber venous graft, and may be a useful model for the transplantation of tissue-engineered liver with access to the portal circulation. 相似文献
998.
To avoid a high-risk operation on a moribund neonate with a ruptured hepatic tumor, transumbilical embolization of the bleeding tumor was attempted in a 2-day-old neonate. A 3F microferret catheter was advanced through the right umbilical artery. After identifying the left hepatic artery feeding the bleeding tumor, Gelfoam (Upjohn, Kalamazoo, MI) particles were injected. Bleeding was successfully controlled. The infant was able to tolerate enteral feeding when stable. Seventeen days after embolization, elective left hepatic lobectomy was performed. Histological examination showed a fetal epithelial type hepatoblastoma. The baby is 13 months old now and is receiving chemotherapy. 相似文献
999.
1000.
We report a rare case of thoracic intramedullary schwannoma. The patient, a 37-year-old woman, showed no evidence of neurofibromatosis. The possible etiology and treatment of the tumor are discussed and a review of literature is presented. 相似文献