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   13395篇
  免费   596篇
  国内免费   61篇
耳鼻咽喉   148篇
儿科学   190篇
妇产科学   113篇
基础医学   1668篇
口腔科学   289篇
临床医学   813篇
内科学   3241篇
皮肤病学   413篇
神经病学   1067篇
特种医学   560篇
外科学   2468篇
综合类   49篇
一般理论   1篇
预防医学   496篇
眼科学   244篇
药学   1036篇
中国医学   41篇
肿瘤学   1215篇
  2023年   54篇
  2022年   133篇
  2021年   221篇
  2020年   116篇
  2019年   176篇
  2018年   197篇
  2017年   172篇
  2016年   220篇
  2015年   203篇
  2014年   255篇
  2013年   388篇
  2012年   528篇
  2011年   627篇
  2010年   340篇
  2009年   330篇
  2008年   509篇
  2007年   618篇
  2006年   605篇
  2005年   607篇
  2004年   597篇
  2003年   604篇
  2002年   631篇
  2001年   451篇
  2000年   469篇
  1999年   443篇
  1998年   192篇
  1997年   170篇
  1996年   145篇
  1995年   130篇
  1994年   112篇
  1993年   103篇
  1992年   367篇
  1991年   322篇
  1990年   329篇
  1989年   303篇
  1988年   296篇
  1987年   295篇
  1986年   281篇
  1985年   226篇
  1984年   152篇
  1983年   152篇
  1982年   60篇
  1981年   61篇
  1979年   120篇
  1978年   60篇
  1977年   63篇
  1974年   55篇
  1973年   61篇
  1972年   66篇
  1970年   50篇
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
31.
Small bowel transplantation (SBT) is associated with a high incidence of infectious complications because of ischemia/reperfusion (I/R) mucosal injury concomitant with potent immunosuppression. In this study, we evaluated whether the cavitary two-layer method (cTLM) could reduce I/R injury and allow early mucosal restoration, particularly after prolonged preservation and transplantation. Canine heterotopic segmental SBT was performed immediately without preservation (group 1), after 24-h preservation in UW solution (group 2) or by the cTLM (group 3). The graft samples were taken 1 h after reperfusion and on days 1, 4 and 7. We assessed graft mucosa with detailed microscopic and electromicroscopic analyses. In Group 3, histological injury and cell apoptosis after transplantation were significantly alleviated and rapidly recovered to a similar level of group 1. The mucosal restoration was morphologically completed within 4 days. In contrast, in group 2, more pronounced mucosal injury and delayed recovery were noted. Crypt cell proliferation activity was well maintained in groups 1 and 3 throughout the experimental period. Our ultrastructural analysis suggested that mitochondrial integrity achieved by the cTLM was a basal mechanism under the prompt mucosal restoration. The cTLM could reduce I/R injury, facilitate mucosal regeneration and restore the nearly normal structure early after SBT.  相似文献   
32.
33.
Forty-six patients in the postoperative period of proximal gastric vagotomy (PGV) for duodenal ulcer (DU) were studied comparatively to verify whether the dividing of the gastroepiploic nerves (Rosati's maneuver) can reduce or not the occurrence of recurrent ulcer as it was proposed. Twenty-one patients who underwent PGV associated with Rosati's maneuver (PGV-R) were compared to 25 after standard PGV (PGV-S), according to several criteria: (1) clinical evaluation; (2) pre and postoperative basal and pentagastrin-stimulated gastric acidity; (3) postoperative basal and pentagastrin-stimulated serum pepsinogen; (4) postoperative basal and sham feeding-stimulated serum gastrin; (5) postoperative endoscopy; (6) endoscopic Congo red test. Both groups were similar (P greater than 0.05) as to age, sex, levels of preoperative gastric acidity and had a 24.4 month average follow-up (12 to 58 months). There has been no significant difference between the techniques studied as to clinical, secretory, morphological or hormonal gastric tests, although PGV-R proved more effective in reducing basal gastric acidity than PGV-S (P less than 0.05). We concluded that Rosati's maneuver does not improve the results obtained with PGV, although it provided greater reduction of basal gastric acidity than PGV-S.  相似文献   
34.
Introduction: One of the causes of pain during insertion of the colonoscope is stretching of the mesenterium by loop formation. The degree of pain differs according to the type of loop formation. Our aims were to study the accuracy of the colonoscopist’s assessment of the presence and type of loop formation and to study the degree of pain in relation to the type of loop by administering the visual analog scale (VAS). Methods: Two hundred and fifty‐seven consecutive patients were enrolled. All procedures were performed by two experienced colonoscopists who were blind to magnetic endoscope imaging view. After the colonoscopy, the colonoscopist was asked to assess the presence and type of loop formation. The degree of pain was assessed using the VAS. Results: The accuracy of estimating N loop, alpha loop, absence of loop formation and U loop was each over 70%. The accuracy of estimating gamma and splenic loop was significantly lower than the accuracy of estimating U loop. Colonoscopy was significantly more painful in women than in men. The degree of pain was significantly higher upon formation of reverse alpha loop and gamma and splenic loop than upon formation of N loop and U loop. Conclusions: Upon formation of reverse alpha loop or gamma and splenic loop, patients experienced more pain and it was difficult for the endoscopists to assess these loops. As women had severe pain compared with men, the use of a pediatric colonoscope or higher dosage of sedation in women should be considered.  相似文献   
35.
We reported a case of X-linked lymphoproliferative syndrome (XLP) with multiple nodular lesions in the brain and lungs. A 21-year-old man was admitted because of one month history of low grade fever, headache, nausea, and amnesia. He developed agammaglobulinemia following Epstein-Barr virus infection at 3-year-old, and thereafter was administered 7.5g of immunoglobulin every 3 weeks with a diagnosis of XLP. Physical examination was unremarkable on admission. Neurological examination revealed disorientation of time, and bilateral gaze-evoked nystagmus. Neuropsychological tests demonstrated impairment of recent memory and calculation. Pleocytosis (83/microl) and increase of protein (1269 mg/dl) and IgG (141 mg/dl) in the CSF were observed. Brain MRI showed multiple nodular lesions with high intense signal on T2-weighted images and Gd-DTPA enhancement on T1-weighted images. Chest CT showed multiple nodular lesions in the bilateral lungs. The needle lung biopsy was performed, which showed infiltration of lymphocytes around the vessels. An immunohistochemical study showed that the infiltrating cells were mainly CD8 positive T lymphocytes. B lymphocyte and plasma cells were not seen. The histological findings excluded intravascular malignant lymphoma and lymphomatoid granulomatosis. Therefore we diagnosed lymphoid vasculitis. The patient developed pancytopenia caused by hemophagocytic syndrome 48 days after admission and was treated with 1 g of methylprednisolone per day for 3 days and a tapered dose of steroid (500 mg to 125 mg of methylprednisolone and 60 mg to 10mg of predonisolone) for 21 days, which resulted in the improvement of clinical features (hemophagocytic syndrome and central nervous system symptoms) and the abnormal CSF findings. The multple nodular lesions in the brain and the lungs shrank 1 month after treatment and disappeared 11 months later. There are few reports concerning lymphoid vasculitis with XLP, and no effective treatment has been described. Our case suggests that steroid therapy may be useful for the treatment of lymphoid vasculitis in XLP.  相似文献   
36.
Objective: We assessed the current role of preoperative and intraoperative autologous blood donation in pediatric open-heart surgery. Methods: Group 1 consisted of 51 patients between 5 and 10 years old who underwent preoperative autologous blood donation. Group 2 consisted of 50 age-matched patients without preoperative donation as controls. Intraoperative donation was conducted in both groups prior to cardiopulmonary bypass. We evaluated perioperative blood cell count, blood loss, and the need for homologous blood products. Results: No serious complications occurred in preoperative or intraoperative donation. Total preoperative donation storage was 17.5±3.4 mL/kg. Intraoperative donation was 21.7 ±6.1 mL/kg in Group 1 and 12.8±4.0 mL/kg in Group 2 (p<0.001). On admission, serum hemoglobin was lower in Group 1 (12.2±1.0 g/dL versus 13.6±1.6 g/dL, p<0.001) but returned postoperatively to the preoperative value. It hovered at a depressed level in Group 2 (12.2±1.4 versus 10.2±1.1 g/dL, p<0.001). The homologous blood requirement was significantly less in Group 1 than in Group 2 (0% versus 10%, p<0.05). Postoperative platelet counts showed similar curves, and blood loss was not statistically significantly different between groups. Conclusion: Preoperative and intraoperative donations are safe and continue to contribute uniquely to blood conservation, providing important options in comprehensive blood conservation programs in current pediatric open-heart surgery.  相似文献   
37.
Some chordomas have a very poor prognosis because of their aggressive growth nature, but the efficacy of repeat operations for these cases has not been well documented. This report concerns 3 patients with aggressive chordoma of the clivus, who underwent operations 6 to 12 times over a period of 8 to 17 years because of symptomatic regrowth. Overall mean interval between repeat operations was 18 months with a range from 5 to 57 months and survival times were 9 to19 years after the first surgery. Main symptoms before each operation were diplopia and visual disturbance. Repeat palliative operations by intentional extradural debulking of the tumour to decompress offending neural structures, as well as maximal removal of the tumour, using appropriate skull base approaches, can mitigate progressive symptoms, and may result in better quality and some prolongation of life, although our patients gradually deteriorated neurologically throughout the clinical course.  相似文献   
38.
A 52-year-old woman who had had 6 months of chemotherapy using mitomycin C and cisplatin for cervical cancer presented with hemolytic uremic syndrome. Conventional plasmapheresis using whole-plasma fraction was ineffective. However, plasmapheresis using the cryosupernatant fraction dramatically improved symptoms of hemolytic anemia and thrombocytopenia in this case. The activity of factor VIII in the cryosupernatant fraction of plasma as a replacement fluid decreased after removal of cryoprecipitate, indicating effective removal of von Willebrand factor. The pathogenesis of her hemolytic uremic syndrome may have been associated with von Willebrand factor multimers contained in the cryoprecipitate of plasma. Similar use of the cryosupernatant fraction of plasma could not be found in other reports of cases of hemolytic uremic syndrome. Plasmapheresis using the cryosupernatant fraction of plasma may improve refractory hemolytic uremic syndrome.  相似文献   
39.
A rare case of solitary bronchial papilloma was reported. A 57-year-old male was admitted to our hospital because of an abnormal shadow on chest X-ray film which was discovered on regular health check up. Bronchoscopic examination revealed a polypoid tumor which obstructed the left B4 bronchus. Serum concentration of CEA was elevated up to 14 ng/ml by Z-GEL method. Left upper lobectomy was performed. On macroscopic examination of the excised specimen, the tumor arose in B4 bronchus and was yellowish white in color and was cauliflower-like in shape sized 3.5 X 1.5 cm. Histopathologically, the tumor consisted of papillary proliferation of stratified squamous epithelium with ciliated columnar epithelial covering. Findings suggestive of inflammation or malignancy were not observed.  相似文献   
40.
Summary In an effort to achieve a simple and less invasive method for the treatment of chronic subdural haematoma, replacement of the haematoma with oxygen by percutaneous subdural tapping was employed in 36 patients. This study was conducted on 23 haematomas in 20 patients, whose computed tomography (CT) scans immediately following the treatment were available for evaluation, with particular regard to distinguishing between their findings and those seen with tension pneumocephalus. The CT features werde divided into two patterns according to the location of oxygen; a convexity type (19 haematomas) and an interhemispheric type (4 haematomas). Analysis of the CT appearances revealed the oxygen was exclusively confined to the haematoma cavity, distinguishing it from the findings in tension pneumocephalus. This observation indicates the safety of replacement of the haematoma with oxygen when combined with our percutaneuous subdural tapping technique which prevents lesions of the inner haematoma membrane.  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