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   2500篇
  免费   188篇
  国内免费   17篇
耳鼻咽喉   70篇
儿科学   73篇
妇产科学   10篇
基础医学   292篇
口腔科学   65篇
临床医学   188篇
内科学   707篇
皮肤病学   45篇
神经病学   233篇
特种医学   98篇
外科学   428篇
综合类   8篇
预防医学   81篇
眼科学   27篇
药学   136篇
中国医学   4篇
肿瘤学   240篇
  2024年   6篇
  2023年   46篇
  2022年   89篇
  2021年   151篇
  2020年   64篇
  2019年   102篇
  2018年   95篇
  2017年   94篇
  2016年   85篇
  2015年   98篇
  2014年   100篇
  2013年   126篇
  2012年   170篇
  2011年   172篇
  2010年   107篇
  2009年   77篇
  2008年   128篇
  2007年   119篇
  2006年   116篇
  2005年   95篇
  2004年   85篇
  2003年   84篇
  2002年   62篇
  2001年   29篇
  2000年   34篇
  1999年   44篇
  1998年   12篇
  1997年   17篇
  1996年   12篇
  1995年   8篇
  1994年   7篇
  1993年   7篇
  1992年   27篇
  1991年   20篇
  1990年   17篇
  1989年   12篇
  1988年   24篇
  1987年   26篇
  1986年   16篇
  1985年   14篇
  1984年   18篇
  1983年   11篇
  1982年   5篇
  1981年   5篇
  1980年   6篇
  1979年   7篇
  1977年   7篇
  1971年   5篇
  1970年   6篇
  1967年   5篇
排序方式: 共有2705条查询结果,搜索用时 15 毫秒
1.
2.

Background

There were few studies assessed the postoperative sarcopenia in patients with cancers. The objective of present study was to assess whether postoperative development of sarcopenia could predict a poor prognosis in patients with adenocarcinoma of esophagogastric junction, (AEG) and upper gastric cancer (UGC).

Methods

Patients with AEG and UGC who were judged as non-sarcopenic before surgery were reassessed the presence of postoperative development of sarcopenia 6 months after surgery. Patients were divided into the development group or non-development group, and clinicopathological factors and prognosis between these two groups were analyzed.

Results

The 5-year overall survival rates were significantly poorer in the development group than non-development group (68.0% vs. 92.6%, P?=?0.0118). Multivariate analyses showed that postoperative development of sarcopenia was an independent prognostic factor for poor overall survival (P?=?0.0237).

Conclusions

Postoperative development of sarcopenia was associated with a poor prognosis in patients with AEG and UGC.  相似文献   
3.
To elucidate the effects of teeth on muscle fibers in the tongue during the developmental process, we examined the expression of muscle contractile proteins and the genes for those proteins in normal mice and microphthalmic (mi/mi) mice with impaired tooth eruption. The mice were observed during the growth period, including weaning, which is when feeding movements undergo major changes. Expression of the myosin heavy chain (MyHC)-2a protein, whose contraction speed is relatively slow, disappeared after weaning in normal mice, while it remained in high concentrations even after weaning in mi/mi mice. The presence of MyHC-2a after weaning in mice with no tooth eruption was attributed to a compensation for lack of proper masticatory function and sucking-like movements, as MyHC-2a is necessary for these movements.  相似文献   
4.
An aggressive pancreatectomy was performed on a 53 year old Japanese man with advanced cancer of the pancreas. The tumor originated from the body of the pancreas and invaded the stomach, duodenum, left kidney, transverse colon and common hepatic artery. An unexpected cancer was also found in the head of the pancreas during the operation. Therefore, total pancreatectomy, total gastrectomy, left adrenonephrectomy, resection of the left transverse colon and dissection of the regional lymph nodes were performed. Resection of the common hepatic artery was also performed, followed by an end-to-end anastomosis between the common hepatic artery and celiac trunk. The postoperative course was uneventful and the patient was doing well until nine months after the operation when multiple metastatic lesions were noted in the liver. He died 391 days after the operation from hepatic failure.  相似文献   
5.
BACKGROUND: Based on epidemiological studies of prevalence, sensitization as well as pollen survey, it is presumed that airborne Japanese cedar pollen (JCP) and cypress (JCyP) have increased progressively for past 40 years. However, because of their large yearly variations, accurate objective and scientific study is required to confirm if it is true or not. METHODS: We analyzed the time trends of JCP and JCy separately in 11 districts throughout Japan where have records of continuous past survey from 1986 to 2005, by regression analysis using net pollen count and their 3 and 5 running means. RESULTS: When significant slope of regression line (regression coefficient) is assumed as p < 0.05 and R2 (coefficient of determination) >0.4, significant increase in airborne pollen was revealed in the use of 5 point running mean (6 districts of total 11 in JCP and 5 in JCyP) but not net count or 3 point running mean because of correction of statistic error due to large yearly variations. This study suggested that our method used for analysis of a recent increase in airborne JCP and JCyP was useful and scientific.  相似文献   
6.
Two hybridomas secreting two monoclonal antibodies IgG1 B1.4 and IgG2a B1.6 were obtained by immunizing BALB/c mice with human bladder cancer cell line EJ-1. In immunohistochemical staining of cryopreserved tissues, B1.4 reacted with 0 of 9 grade 1 TCC, 6 of 11 grade 2, all of 6 grade 3 and five metastatic specimens. The antigen recognized by B1.4 was not expressed by normal urothelial cells but were expressed by vascular endothelial cells and muscle of tunica media. The target antigen of B1.6 was expressed by normal urothelial cells and all grade of TCC. In this study, it was demonstrated that poorly differentiated bladder cancer and metastatic specimens of bladder cancer express a vascular carbohydrate antigen. Taking the escape mechanism of immune surveillance, into consideration, it is possible that the antigen recognized by B1.4 is an indicator of metastatic potential of bladder cancer.  相似文献   
7.
MR appearance of parasymphyseal insufficiency fractures of the os pubis   总被引:1,自引:0,他引:1  
Objective. To clarify the MRI features of parasymphyseal insufficiency fractures of the os pubis. Design and patients. MRI was performed in four postmenopausal women with parasymphyseal insufficiency fractures. The diagnosis was confirmed with plain films in every patient. T1-weighted and T2-weighted images were obtained in four patients using a 1.5-T unit. Postcontrast T1-weighted imaging was also done in three patients. Results and conclusions. MRI of pubic parasymphyseal insufficiency fracture characteristically demonstrates a hyperintense mass lesion with a hypointense rim on T2-weighted imaging, showing peripheral and septal enhancement after contrast administration. It is important to have this entity in mind in patients with osteoporosis, especially in patients with a history of pelvic irradiation for malignant disease, so as not to misinterpret it as a chondroid tumor or bone metastasis.  相似文献   
8.
The effect of prostaglandin E1 (PGE1) on platelets is mediated through the PGE1 receptor and the consequent maintenance of the platelet's discoid shape. The effects of PGE1 and dibutyryl cAMP (dbcAMP) on the deformability of human platelets were studied. Deformability tests based upon the micropipette aspiration on the platelets were performed by using pipettes with radii (Rp) of 0.26-0.36 gm. The time course of the extension length (Dp, in μg) of the platelets in response to aspiration with a negative pressure (ΔP) of 5 cm H2 O (ΔP × Rp = 0.15 dynes/cm) was analyzed. PGE1 treatment (0.1 μM) resulted in a decrease of platelet deformability as compared with results obtained for apparently non-activated, control platelets. The deformation index, i.e., Dp/Rp (PGE1 -treated) / Dp/Rp (control), was significantly reduced to 0.90 ± 0.04. DbcAMP treatment also significantly decreased the deformability of platelets and this decrease was dbcAMP dose dependent. In contrast, colchicine- or cytochalasin D-treated platelets increased deformability. PGE1 -treated platelets had a higher [cAMP]i than controls. Platelets treated with PGE1 or dbcAMP showed a reduced [Ca2+]i increment induced by thrombin as compared to non-treated controls. These results indicate that PGE1 and dbcAMP treatment of platelets is accompanied by an enhancement of platelet resistance to deformation. The increased [cAMP]i and low [Ca2+]i after PGE1 treatment may limit the rearrangement of cytoskeleton and thus enhance platelet resistance to deformation.  相似文献   
9.
For the evaluation of myocardial perfusion in patients with left bundle branch block (LBBB), we performed exercise stress (Ex)-redistribution (RD) myocardial tomography with thallium-201 (201Tl) in 23 patients with LBBB and without coronary artery disease (CAD). Myocardial images in patients with LBBB were compared with those of 9 patients with CAD who showed Ex induced transient septal defect. Bull'-eye maps (201Tl distribution maps at Ex and RD and 201Tl washout rate [WOR] map) were made from myocardial tomograms. In 23 patients with LBBB, 15 patients (65%) developed myocardial perfusion abnormality. In 10 (67%) of these 15 patients, transient perfusion defect appeared in the entire septum (diffuse type). On the other hand in 5 patients (33%), localized fixed perfusion defect developed at the boundary between septum and anterior wall (focal type). In focal type, every patient had other disease such as hypertension, aortic stenosis or sick sinus syndrome. While in patients with diffuse type, other diseases were observed in 30% (p less than 0.05) and they were limited to hypertension or diabetes mellitus. These facts suggested that mechanisms of perfusion abnormalities might be different between these two groups. We compared the perfusion abnormality between LBBB diffuse type and CAD. The extent of the defects was not different between two groups. Although apex was included within the defect in 89% of CAD population, apical defect was observed in only 20% of diffuse type (p less than 0.05). Minimal 201Tl WOR and 201Tl uptake ratio of septum to lateral wall indicated that exercise induced septal defect was slighter in diffuse type than CAD.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   
10.
Aquaporins (AQPs) confer a high water permeability on cell membranes and play important parts in secretory and absorptive epithelia in kidney and other organs. Here we investigate whether AQPs are expressed in the sensory epithelia of the inner ear, where a precise volume regulation is crucial. By use of specific antibodies it was found that the inner ear contains AQP1 and 4 while being devoid of detectable levels of AQP2, 3 or 5. Immunofluorescence and postembedding immunogold labelling revealed a strictly non-epithelial distribution of AQP1, confirming previous data. In contrast, AQP4 protein and mRNA (visualized by in situ hybridization) were concentrated in select types of supporting cell, including Hensen's cells and inner sulcus cells. Immunogold particles signalling AQP4 were confined to the basolateral plasma membrane of Hensen's cells and to the basal plasma membrane of Claudius cells and inner sulcus cells. AQP4 was also found in supporting cells of the vestibular end organs, but was absent from transitional epithelial cells and dark cells. Strong labelling for AQP4 and AQP4-mRNA was associated with the central part of the cochlear and vestibular nerves. Hair cells were consistently unlabelled. Our findings indicate that AQP4 may facilitate osmotically driven water fluxes in the sensory epithelia of the inner ear and thus contribute to the volume and ion homeostasis at these sites.  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