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   2304篇
  免费   105篇
  国内免费   18篇
耳鼻咽喉   124篇
儿科学   92篇
妇产科学   94篇
基础医学   106篇
口腔科学   62篇
临床医学   169篇
内科学   605篇
皮肤病学   55篇
神经病学   88篇
特种医学   106篇
外科学   545篇
综合类   40篇
预防医学   48篇
眼科学   74篇
药学   67篇
中国医学   2篇
肿瘤学   150篇
  2024年   1篇
  2023年   11篇
  2022年   18篇
  2021年   50篇
  2020年   41篇
  2019年   38篇
  2018年   54篇
  2017年   51篇
  2016年   77篇
  2015年   74篇
  2014年   103篇
  2013年   139篇
  2012年   195篇
  2011年   165篇
  2010年   92篇
  2009年   87篇
  2008年   187篇
  2007年   208篇
  2006年   165篇
  2005年   169篇
  2004年   136篇
  2003年   112篇
  2002年   97篇
  2001年   33篇
  2000年   21篇
  1999年   14篇
  1998年   15篇
  1997年   10篇
  1996年   13篇
  1995年   8篇
  1994年   6篇
  1993年   4篇
  1992年   8篇
  1991年   4篇
  1990年   4篇
  1989年   1篇
  1988年   1篇
  1986年   2篇
  1985年   1篇
  1984年   5篇
  1982年   2篇
  1981年   1篇
  1980年   2篇
  1974年   1篇
  1971年   1篇
排序方式: 共有2427条查询结果,搜索用时 15 毫秒
131.
In 1923, Masson1 described an unusual papillary endothelial proliferation that he named as "hemangioendotheliome vegetant intravasculaire". In 1976, Clearkin and Enzinger2 coined the term intravascular papillary endothelial hyperplasia (IPEH) that is now in use. This term refers to the presence of endothelium lined papillary projections within a vascular space. Characteristically, the papillary structures are composed of a single layer of swollen or plump endothelial cells without cellular pleomorphism, mitotic activity or necrosis.  相似文献   
132.
AIMS: To evaluate the ocular axial length as a risk factor for development of central retinal vein occlusion (CRVO) and branch retinal vein occlusion (BRVO). METHODS: Ocular axial lengths were measured, by A-scan ultrasonography, in 17 patients with CRVO and 41 patients with BRVO and compared with those of contralateral unaffected eyes and 66 age matched controls. RESULTS: In 17 patients with CRVO the mean axial length of affected eyes was 22.25 (SD 0.19) mm and of unaffected eyes was 22.61 (0.13) mm. In 41 patients with BRVO the mean axial length of affected eyes was 22.89 (0.11) mm and of unaffected eyes was 22.99 (0.12) mm. CONCLUSION: These findings confirm that the axial lengths in CRVO and BRVO were significantly shorter than in the controls. This significant difference may be a risk factor in the development of CRVO and BRVO.  相似文献   
133.
The value of serum Bcl-2 levels in advanced lung cancer patients   总被引:2,自引:0,他引:2  
Overexpression of the Bcl-2 protein was associated with a favorable prognostic factor for survival in lung cancer patients, especially nonsmall cell lung carcinoma. The present study was conducted to investigate the value of serum Bcl-2 levels in advanced lung cancer patients. Fifty patients with advanced lung carcinoma pathologically verified and 18 healthy controls were investigated. Serum samples were obtained on the first admission before the chemotherapeutic treatment were given. Serum Bcl-2 levels were determined by using anti-Bcl-2 monoclonal coating antibody. The baseline serum Bcl-2 levels were significantly higher in patients with lung cancer than in the control group (p<0.001). Serum Bcl-2 levels were elevated in 48 (96%) advanced lung cancer patients. None of the prognostic parameters analyzed, such as age of patient, gender, histology, stage of disease, erythrocyte sedimentation rate, serum albumin, hemoglobin, CEA, NSE, LDH, performance of patient, weight loss, and response to chemotherapy, was significantly correlated with Bcl-2 serum concentrations. The serum Bcl-2 concentrations were not changed with cisplatin-based cytotoxic chemotherapy regardless of response (p=0.76). No prognostic value of serum Bcl-2 was determined. In conclusion, the results of the present study, which is the first study to determine serum Bcl-2 levels in lung cancer, suggest that decreased apoptosis occurred due to the effect of serum Bcl-2 elevation in lung cancer patients. Serum Bcl-2 level was of diagnostic but not prognostic value in lung cancer patients. However, more studies are needed to define the role of Bcl-2 in the diagnosis and prognosis of lung cancer.  相似文献   
134.
135.
BACKGROUND: The aims of this study were to determine the presence of trefoil factor family-3 (TFF3) expression in biliary epithelial cells (BECs) of chronic graft-versus-host disease (cGVHD) of the liver after allogeneic hematopoietic cell transplantation, to compare such expression in chronic liver diseases (CLD) with/without predominantly biliary disease, and to assess the effect of bile duct injury on the degree of TFF3 expression in BECs of cGVHD. METHODS: A total of 82 paraffin-embedded liver biopsy samples were reviewed. These samples were basically divided into two distinct groups according to the presence of ductal injury: group 1 with CLD and predominantly biliary disease (n=26: 17 cGVHD and 9 primary biliary cirrhosis [PBC]) and group 2 with CLD and predominantly parenchymal liver disease (n=56: 20 steatohepatitis and 36 chronic viral hepatitis). Group 2 was used as the controls. Immunohistochemistry was performed using a polyclonal anti-TFF3 antibody. Real-time quantitative PCR was used for the detection of TFF3 mRNA expression. RESULTS: Positive TFF3 immunohistochemical staining and the presence of TFF3 messenger RNA gene expression was demonstrably higher in group 1 than that in group 2 (P<0.0001 and P<0.05, respectively). No significant difference in terms of positive TFF3 stained BECs between GVHD and PBC samples was observed (P>0.05). The extent of TFF3 expression in GVHD samples with severe ductal injury were significantly more common than that of GVHD samples with mild/moderate ductal injury (P<0.0001). CONCLUSIONS: The expression of TFF3 in cGVHD of the liver is increased in response to bile duct damage and repair. Such expression seems to be related the severity of ductal injury.  相似文献   
136.
BACKGROUND: Smear-negative pulmonary tuberculosis (SNPTB) constitutes a major problem in countries with a moderate or high TB prevalence. The value of high-resolution computed tomography (HRCT), chest x-ray and other clinical findings in determining activity of SNPTB were investigated. METHODS: The study population consisted of 85 patients with suspected SNPTB, of whom 52 were confirmed as active pulmonary TB according to either culture positivity for Mycobacteriun tuberculosis or demonstration of caseous granulomatous inflammation. The remaining 33 patients accepted inactive TB sequel. RESULTS: Cough and expectoration were significantly frequent in inactive group whereas chest pain was detected higher in active patients. Sensitivity, specificity, positive predictive value, negative predictive value and diagnostic accuracy of HRCT in detecting disease activity were 88, 88, 92, 83 and 88%, respectively. Centrilobular nodules, other non-calcified nodules, consolidation and cavity were significantly higher on HRCT in active group. Chest x-ray scores that were graded 1 to 3 showed a linear trend for the disease activity. CONCLUSIONS: HRCT has good diagnostic value in detecting activity of SNPTB, and some clinical findings may help in predicting the activity.  相似文献   
137.
138.
To investigate the effect of cyclosporine A (Cyc A) on the development of fibroadenomas, 30 renal transplant patients and 20 chronic renal failure patients on dialysis were breast examined with ultrasonography and/or mammography. Of the renal transplant patients, 17 were receiving Cyc A-based combination therapy for immunosuppression. All patients were female with the age range of 29.7+/-9.2 years in the transplant group and 33.95+/-9.91 in the dialysis group. Eight of the 17 patients receiving Cyc A had fibroadenomas, 5 of them having bilateral lesions. None of the other patients, those on dialysis and on non-Cyc A combination therapy had fibroadenomas. A significant difference for fibroadenoma incidence in patients receiving Cyc A combination immunosuppression was found.  相似文献   
139.
AIM: To delineate whether coronary arteriovenous malformations have different properties than classical discrete coronary artery fistulae. METHODS: Group 1 included 17 patients with discrete coronary fistula that represents a coronary artery fistula draining into any cardiac chamber. Group 2 included six patients with coronary arteriovenous malformations representing extensive coronary artery malformation. Cardiopulmonary bypass was used in 12 of the Group 1 patients and 5 in Group 2. RESULTS: There was no operative mortality in either group. Following a hemodynamically nonsignificant residual fistulous communication, which was detected by repeat coronary angiography in Group 2; we changed our surgical technique of suture ligation on beating heart. Then we preferred pulmonary arteriotomy and sutured the orifice of coronary arteriovenous malformations from within the chamber. CONCLUSIONS: Coronary arteriovenous malformations have different morphology and also complex progression properties when compared with discrete coronary artery fistulae. Surgical repair of coronary arteriovenous malformation should be done by suturing the multiple drainage holes inside the draining chamber. Suture ligation of coronary arteriovenous malformation is difficult due to the fragile vessel.  相似文献   
140.
A 20-year-old pregnant woman was admitted to our department with symptoms of deep venous thrombosis in the left lower extremity and excessive lumbar pain. Low-molecular-weight heparin was administered. She recovered with this treatement, however, severe lumbar pain continued. A lumbar magnetic resonance imageg showed dilated epidural veins compressing the roots and acute thrombosis of the inferior vena cava extending to renal veins. During the same period she had acute deep venous thrombosis in her right leg. An urgent venous thrombectomy was performed. Sciatica and deep venous thrombosis resolved after the operation. Low-molecular-weight heparin was administered until the end of her pregnancy.  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