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   128918篇
  免费   11266篇
  国内免费   6718篇
耳鼻咽喉   1224篇
儿科学   1960篇
妇产科学   2930篇
基础医学   13464篇
口腔科学   2681篇
临床医学   16035篇
内科学   20174篇
皮肤病学   1590篇
神经病学   6397篇
特种医学   4197篇
外国民族医学   40篇
外科学   13342篇
综合类   19334篇
现状与发展   20篇
一般理论   18篇
预防医学   9433篇
眼科学   3446篇
药学   13513篇
  115篇
中国医学   6562篇
肿瘤学   10427篇
  2024年   347篇
  2023年   1717篇
  2022年   4017篇
  2021年   5453篇
  2020年   4056篇
  2019年   3706篇
  2018年   3943篇
  2017年   3705篇
  2016年   3309篇
  2015年   5235篇
  2014年   6736篇
  2013年   6949篇
  2012年   10125篇
  2011年   10871篇
  2010年   7486篇
  2009年   6153篇
  2008年   7784篇
  2007年   7778篇
  2006年   7319篇
  2005年   6701篇
  2004年   4839篇
  2003年   4401篇
  2002年   3650篇
  2001年   3096篇
  2000年   2854篇
  1999年   2650篇
  1998年   1319篇
  1997年   1230篇
  1996年   995篇
  1995年   955篇
  1994年   892篇
  1993年   510篇
  1992年   891篇
  1991年   802篇
  1990年   673篇
  1989年   572篇
  1988年   528篇
  1987年   450篇
  1986年   357篇
  1985年   284篇
  1984年   184篇
  1983年   167篇
  1982年   95篇
  1981年   93篇
  1979年   140篇
  1978年   111篇
  1977年   83篇
  1974年   94篇
  1973年   72篇
  1972年   87篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
3.
4.
5.
From 1955 to 1984, radical neck dissection (RND) had been done in 300 salivary carcinoma patients, 114 of which had regional lymph node metastasis, with a 38% metastatic rate. Respective 3, 5, 10, 15, 20 year survival rates were 76, 64, 47, 35, 35% in a 3 to 20 years follow-up study in 283 patients (94.33%). The following four points are concluded: 1. The metastatic rate is determined not only on tumor staging, but more to its typing (pathologic behaviour). 2. Elective RND gave a better prognosis than therapeutic and negative metastasis has a better survival chance than positive where the low level metastasis is the worst. 3. According to pathologic typing, Elective RND is indicated for undifferentiated adenocarcinoma, high malignant mucoepidermoid carcinoma, squamous cell carcinoma, adenocarcinoma and papillary cystic adenocarcinoma, therapeutic RND for malignant pleomorphic adenoma, acinic cell carcinoma and mucoepidermoid carcinoma. 4. Unilateral RND is indicated for all but sublingual and buccal tumors.  相似文献   
6.
While balloon valvuloplasty has been widely used for the treatment of congenital valvular pulmonary stenosis (PS) in children and adults, its use in elderly patients is less common. An 80-year-old woman with congenital valvular PS received valvuloplasty with double-balloon technique. Right ventricle systolic pressure and pulmonary valve systolic pressure gradient decreased from 95 to 44 mm Hg and from 75 to 35 mm Hg, respectively. Follow-up Doppler echocardiography 2 months later showed further decrease in the transvalvular systolic pressure gradient to 29 mm Hg. The patient had symptomatic relief, and no major complication was noted. Balloon pulmonary valvuloplasty can be an effective treatment for elderly patients with congenital valvular PS.  相似文献   
7.
X-linked hyper-immunoglobulin M (IgM) syndrome (XHIGM) is a rare genetic primary immunodeficiency disease caused by mutations of the CD40 ligand (CD40L) gene with normal or elevated levels of IgM and markedly decreased serum IgG, IgA, and IgE. Liver disease may occur as a clinical manifestation in XHIGM. This complication appears to increase with age. We report an 18-year-old male patient who had recurrent episodes of acalculous cholecystitis (AC) and sclerosing cholangitis (SC). The diagnosis of XHIGM was confirmed by the finding of CD40L expression < 1% of normal and a tyrosine 169 asparaginase (t526a) mutation in exon 5 (the tumor necrosis factor domain) of the CD40L gene. The patient had direct hyperbilirubinemia (direct bilirubin 5.5 mg/dL, total bilirubin 8.7 mg/dL), cholestasis (alkaline phosphatase 1133 U/L, gamma-glutamyl transferase 1019 U/L) and elevated transaminases (aspartate aminotransferase 70 U/L, alanine aminotransferase 101 U/L). Findings on abdominal ultrasound and abdominal computed tomography were compatible with AC. After the fourth episode of cholecystitis, cholecystectomy and liver biopsy were performed. Operative cholangiography revealed poor opacification of the hepatic duct and proximal common bile duct; the upstream intrahepatic bile ducts were not visualized. The biopsy specimen showed marked fibrosis of the portal areas. Enterococcus species was cultured from the bile. Children or adolescents with recurrent AC and SC should be evaluated for an underlying immunodeficiency syndrome such as XHIGM.  相似文献   
8.
BACKGROUND AND PURPOSE: This report describes the results of matched-unrelated-donor transplant for leukemia or myelodysplasia in the first 23 recipient children at a single medical center in Taiwan. METHODS: Between August 1994 and February 2003, 23 consecutive children with leukemia or myelodysplasia underwent matched-unrelated-donor bone marrow transplantation (BMT). The preparative regimen consisted of fractionated total body irradiation and cyclophosphamide in 6 patients; busulfan in combination with etoposide and cyclophosphamide in 4 patients who received cranial irradiation before transplantation; and busulfan and cyclophosphamide in 13 patients. RESULTS: Engraftment was achieved in 91.3% of cases. Acute graft-versus-host disease (GVHD) occurred in 18 of 21 patients who engrafted (85.7%). Event-free survival for all patients was 24.46 +/- 9.24%. The 12 children with standard-risk disease had better event-free survival than the 11 children with high-risk disease (46.88 +/- 15.03% vs 0%, p < or = 0.001). CONCLUSIONS: The major obstacles to successful matched-unrelated-donor BMT are acute GVHD, relapse and infection. Early transplantation and patient selection, prophylactic and therapeutic maneuvers for GVHD, as well as appropriate donor selection and virus prophylaxis may improve the results.  相似文献   
9.
In primary visual cortex of hooded rats, pyramidal cells in layer V may be classified as long, medium, or short, on the basis of the layer in which the apical dendrite terminates. The present study determines which of these types of pyramidal cells project to the superior colliculus. Two different strategies were used to label corticotectal cells with horseradish peroxidase (HRP). In the first set of experiments, a large number of corticotectal cells were labeled by retrograde transport following injection of HRP into the superior colliculus. In the second set of experiments, single unit recording was used to identify corticotectal cells physiologically by antidromic activation from the superior colliculus. These cells were then impaled and labeled by intracellular iontophoresis of HRP. The results from both techniques suggest that only long pyramidal cells send an axon to the superior colliculus. These cells are distinguished by an apical dendrite that extends into layer I. We conclude that in hooded rats corticotectal cells in primary visual cortex are the long pyramids in layer V.  相似文献   
10.
An unusual, elongated, refractile cell morphology was observed in keratinocytes cultured from three patients with non-lethalis forms of junctional epidermolysis bullosa (JEB). To determine whether these changes might be related to altered cell adhesion, keratinocyte strains established from one patient were examined for adhesive, structural, and functional characteristics. JEB keratinocytes expressed keratin tonofilaments, as determined by staining with AE1 monoclonal antibodies and direct observation of tonofilaments by electron microscopy. JEB keratinocytes showed diminished cell-substratum adhesions, judged by interference reflection microscopy. Areas of diminished cell-substratum adhesion corresponded to F-actin-rich cell adhesions (focal adhesions) and not to cellular areas that abundantly express hemidesmosomal antigens. Analysis of cell-substratum adhesion by electron microscopy revealed extensive areas of cell-substratum separation in JEB keratinocytes that were not present in normal keratinocytes maintained in serum-free medium. Normal keratinocytes displayed numerous regions of focal contact between the ventral plasma membrane and the culture substratum, but these structures were not seen in JEB keratinocytes. Bundled actin filaments (stress fibers) were greatly diminished in expected regions of cell-substratum adhesion in JEB keratinocytes and, instead, displayed disorganized individual filaments. The growth rate of JEB keratinocytes was quite slow in culture, with a population doubling time of 2.7 d versus 1.5 d for normal keratinocytes under identical conditions. JEB keratinocytes also displayed a reduced ability to aggregate into colonies upon exposure to medium with increased extracellular calcium. JEB keratinocytes thus display adhesive, structural, and functional abnormalities that suggest this cell type may be central to the pathogenesis of junctional epidermolysis bullosa. Study of affected keratinocytes could be important to characterize associated molecular pathologies.  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