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   1638篇
  免费   97篇
  国内免费   12篇
耳鼻咽喉   25篇
儿科学   30篇
妇产科学   31篇
基础医学   193篇
口腔科学   30篇
临床医学   100篇
内科学   383篇
皮肤病学   54篇
神经病学   81篇
特种医学   76篇
外科学   258篇
综合类   3篇
预防医学   141篇
眼科学   24篇
药学   88篇
中国医学   3篇
肿瘤学   227篇
  2023年   14篇
  2022年   45篇
  2021年   52篇
  2020年   28篇
  2019年   38篇
  2018年   69篇
  2017年   45篇
  2016年   56篇
  2015年   41篇
  2014年   57篇
  2013年   60篇
  2012年   101篇
  2011年   113篇
  2010年   58篇
  2009年   51篇
  2008年   75篇
  2007年   95篇
  2006年   84篇
  2005年   101篇
  2004年   59篇
  2003年   69篇
  2002年   55篇
  2001年   34篇
  2000年   26篇
  1999年   20篇
  1997年   10篇
  1996年   8篇
  1995年   12篇
  1994年   12篇
  1993年   8篇
  1992年   16篇
  1991年   10篇
  1990年   14篇
  1989年   14篇
  1988年   22篇
  1987年   19篇
  1986年   9篇
  1985年   10篇
  1983年   8篇
  1979年   7篇
  1977年   6篇
  1975年   9篇
  1974年   9篇
  1973年   7篇
  1972年   6篇
  1971年   9篇
  1970年   7篇
  1969年   9篇
  1967年   6篇
  1966年   13篇
排序方式: 共有1747条查询结果,搜索用时 15 毫秒
1.
2.
3.
We applied a forearm flap combined with a gracilis muscle flap for total reconstruction of the lower lip. The motor nerve of the gracilis muscle was repaired to the buccal branch in the cheek. The patient obtained good sphincter function for eating and speaking, and he could inflate a balloon without air leakage.  相似文献   
4.
Pancreatic metastasis of malignant melanoma is rarely diagnosed while the patient is alive. We report a case of metastatic melanoma of the pancreas in a 35-year-old woman presenting with a solid mass of the pancreas. Her past medical history included a radical hysterectomy 2 years previously for malignant melanoma of the vagina. Twelve months later, lung metastasis was also resected. EUS-guided fine needle aspiration (EUS-FNA) identified that the pancreatic tumor was histologically and immunohistochemically identical to the surgical specimen of her lung neoplasm. Imaging studies including US, CT, and MRI have limited value to distinguish the tumors from primary ductal adenocarcinoma. EUS-FNA can provide tissue diagnosis from pancreatic masses, specifically when other modalities have failed.  相似文献   
5.
6.
Abstract: Suitable evaluation systems are critical for ranking various biomaterials in order to develop a method to design and synthesize nonthrombogenic biomaterials. We have recently developed an in vitro test system to evaluate platelet/biomaterial interactions in whole blood. The system consists of a parallel plate flow cell and epifluorescent video microscopy (EVM). A glass coverslip coated with a polymer was incorporated into the flow cell, and blood was perfused using a syringe pump via a polymer–coated PVC tubing connected to the flow cell. Whole human blood was anticoagulated with heparin (2 U/ml), and the platelets were labeled with the fluorescent dye mepacrine (5 μM). This system permitted real–time and dynamic observations of platelet/biomaterial interactions in whole blood under a defined flow condition. In order to evaluate the feasibility of this system, two different segmented polyether–polyurethanes (SPEUs), PU–PTMG(650) and PU–PTMG(2000), were chosen as test polymers. Surface characteristics verified with electron spectroscopy for chemical analysis (ESCA) and contact angle measurements showed similar results in both SPEUs. Blood was perfused at a wall shear rate of 200 s–1 for 20 min. Excitation light was applied for 2 s at 1 min intervals. The real–time image was then analyzed at each time point for the percentage of surface area of platelet coverage. Plasma β–thromboglobulin (β–TG) levels were also measured before and after each run. PU–PTMG(650) showed a significantly higher number of adhered platelets than PU–PTMG(2000) at each time point. β–TG levels of PU–PTMG(650) were also higher than those of PU–PTMG(2000), which is comparable to the results of EVM. Thus, this EVM system has been proven to be an excellent and highly sensitive in vitro analytical method for evaluating platelet/biomaterial interactions.  相似文献   
7.
AIMS: p27 is a prominent regulator of cell proliferation by universally inhibiting the cell cycle, while Jun activation domain-binding protein 1 (Jab1), a multifunctional cell signaling protein, contributes to carcinoma progression by degrading p27. In this study, we investigated the expression of these proteins in medullary thyroid carcinoma. METHODS: We immunohistochemically examined Jab1 and p27 expression in 64 medullary thyroid carcinomas. RESULTS: Of the 64 cases examined, decreased p27 expression was observed in 38 cases (59.4%). The p27 expression level was inversely linked to tumour size as well as plasma calcitonin level. Jab1 expression level was generally high, and 46 cases (71.9%) were classified as overexpressing Jab1. The incidence was higher than those in papillary and follicular carcinomas, which were previously reported. Jab1 expression level was inversely linked to that of p27, and all five cases with only cytoplasmic but not nuclear staining of p27 overexpressed Jab1. CONCLUSIONS: These findings suggest that (1) decrease in p27 expression may contribute to local tumour growth; (2) Jab1 expression is related to the progression of medullary carcinoma by decreasing the amount of p27 in the cell and accelerating its degradation; and (3) Jab1 may play a more vital role in the pathogenesis of medullary carcinoma than papillary and follicular carcinomas.  相似文献   
8.
By Western blot analysis, the expression level of aquaporin (AQP) 5 in the submandibular gland (SMG) was found to be different among individual rats of the Sprague-Dawley (SD) strain. Such differences were observed for AQP5 but not for AQP1 and consequently the SD strain was divided into two groups, one expressing a high level of AQP5 and the other a low one. The difference in average intensity of expression between the two groups was more than twofold. Immunohistochemical analysis of the SMG demonstrated that the AQP5 protein was localized in the basal and apical/lateral plasma membrane of acinar cells in rats expressing the high level of AQP5. In the rat expressing the low level, however, this channel protein was localized strongly in the apical/lateral plasma membrane, but only very weakly in the basal membrane of the acinar cells. Such a diverse localization of AQP5 was confirmed by Western blotting as well. Breeding between brother and sister was repeated for two times within high expressers and low expressers to obtain the third generation progenies (F2); the AQP5 level of the SMG in the third generation (F2 rats) from high expressers was significantly higher than the F2 from low expressers. Our present study suggests the existence of genetic variation in the expression of a water channel protein, AQP5, in rats.  相似文献   
9.
Bilharzial bladder cancer is one of the most common types of malignancy in both men and women in several developing countries including Egypt. It has several unique clinical, epidemiological, and histological characteristics, suggesting that it is an entity distinct from bladder cancer seen in Western countries. Genetic alterations in bilharzial-related bladder cancer have been studied infrequently, especially in the advanced stages of disease, that is, T3 and T4 classifications. The objective of this study was to extend establishing the baseline cytogenetic profile of this type of malignancy to early T1 and T2 classifications. For this purpose, fluorescence in situ hybridization was applied to interphase nuclei of frozen-stored samples with biotinylated repetitive DNA probes specific for all chromosomes to detect numerical chromosome changes in 35 patients presenting with relatively early-stage pT1 and pT2 disease. Eleven cases had squamous cell carcinoma (SCC) and 24 had transitional cell carcinoma. Six of 24 transitional cell carcinomas had diploid chromosome counts with all the probes. Numerical chromosome aberrations were detected in 18 cases (75%). In 12 cases, a loss of chromosome 9 was observed. In three cases, an additional loss of chromosome 17 was detected. One case demonstrated a loss of chromosome 10, whereas another two cases showed a gain of chromosome 7, next to a loss of chromosome 9. Loss of chromosome Y was observed in nine of the 27 male cases studied (33.3%), in which only one case showed an abnormality whereas four cases were detected next to loss of chromosome 9, and one case showed gain of chromosome 7. Five cases showed loss of chromosome 19 whereas gain of chromosome 4 was detected in two cases. Two of 11 samples of SCC had normal diploid chromosome counts with all the probes used. In four of 11 cases (36.4%) underrepresentation of chromosome 9, compared with the other chromosomes, was detected. An additional loss of chromosome 17 and gain of chromosome 7, next to loss of chromosome 9, was detected in three cases. One case showed loss of chromosome 17 as the only numerical aberration. Loss of the Y chromosome was detected in three cases of which one case had gain of chromosome 7 and one case had loss of chromosome 19. No correlation was found between any of the clinicopathologic parameters examined in this study and the presence or absence of any numerical chromosomal aberrations except for the significant association between schistosomal history and loss of Y chromosome (P=0.007).  相似文献   
10.
A 66-year-old male with osteoclast-like giant cell tumor of the liver that arose in the non-cirrhotlc liver is presented. The liver tests were almost normal, and plasma levels of alpha-fetoprotein and carcinoembryonic antigen were within normal limits. The findings of liver scan by 99mTc phytate, celiac angiography, and CT scans are described for the first time for this rare neoplasm, showing a large, unresectable liver tumor. Histologically, the tumor mainly consisted of osteoclast-like giant cells and mononuclear cells, which were focally arranged in a vaguely trabecular pattern and sarcomatous pattern. By an electromicroscopic study, however, no definitive evidence was obtained whether it arose from epithelial cells or nonepithellal cells. Various clinicopathological features were described and compared with previously reported cases including two cases arising in the liver.  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