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   3227篇
  免费   124篇
  国内免费   325篇
耳鼻咽喉   15篇
儿科学   32篇
妇产科学   23篇
基础医学   438篇
口腔科学   34篇
临床医学   187篇
内科学   656篇
皮肤病学   19篇
神经病学   193篇
特种医学   54篇
外国民族医学   1篇
外科学   282篇
综合类   544篇
现状与发展   13篇
预防医学   156篇
眼科学   110篇
药学   439篇
  2篇
中国医学   145篇
肿瘤学   333篇
  2024年   21篇
  2023年   76篇
  2022年   45篇
  2021年   37篇
  2020年   17篇
  2019年   17篇
  2018年   12篇
  2017年   7篇
  2016年   20篇
  2015年   29篇
  2014年   51篇
  2013年   39篇
  2012年   618篇
  2011年   625篇
  2010年   120篇
  2009年   40篇
  2008年   314篇
  2007年   332篇
  2006年   286篇
  2005年   207篇
  2004年   194篇
  2003年   158篇
  2002年   125篇
  2001年   64篇
  2000年   71篇
  1999年   55篇
  1998年   26篇
  1997年   13篇
  1996年   7篇
  1995年   4篇
  1994年   10篇
  1993年   4篇
  1992年   3篇
  1991年   3篇
  1990年   2篇
  1989年   2篇
  1987年   4篇
  1986年   3篇
  1985年   1篇
  1984年   4篇
  1983年   1篇
  1982年   5篇
  1981年   1篇
  1980年   1篇
  1963年   1篇
  1957年   1篇
排序方式: 共有3676条查询结果,搜索用时 31 毫秒
71.
AIM: To investigate the expression of chondroitin sulphate proteoglycans (CSPGs) in rat liver tissues of hepatocellular carcinoma (HCC).METHODS: Thirty male Sprague Dawley rats were randomly divided into two groups: control group (n = 10) and HCC model group (n = 20). Rats in the HCC model groups were intragastrically administrated with 0.2% (w/v) N-diethylnitrosamine (DEN) every 5 d for 16 wk, whereas 0.9% (w/v) normal saline was administered to rats in the control group. After 16 wk from the initiation of experiment, all rats were killed and livers were collected and fixed in 4% (w/v) paraformaldehyde. All tissues were embedded in paraffin and sectioned. Histological staining (hematoxylin and eosin and Toluidine blue) was performed to demonstrate the onset of HCC and the content of sulphated glycosaminoglycan (sGAG). Immunohistochemical staining was performed to investigate the expression of chondroitin sulphate (CS)/dermatan sulphate (DS)-GAG, heparan sulphate (HS)-GAG, keratan sulphate (KS)-GAG in liver tissues. Furthermore, expression and distribution of CSPG family members, including aggrecan, versican, biglycan and decorin in liver tissues, were also immunohistochemically determined.RESULTS: After 16 wk administration of DEN, malignant nodules were observed on the surface of livers from the HCC model group, and their hepatic lobule structures appeared largely disrupted under microscope. Toluidine blue staining demonstrated that there was an significant increase in sGAG content in HCC tissues when compared with that in the normal liver tissues from the control group [0.37 ± 0.05 integrated optical density per stained area (IOD/area) and 0.21 ± 0.01 IOD/area, P < 0.05]. Immunohistochemical studies demonstrated that this increased sGAG in HCC tissues was induced by an elevated expression of CS/DS (0.28 ± 0.02 IOD/area and 0.18 ± 0.02 IOD/area, P < 0.05) and HS (0.30 ± 0.03 IOD/area and 0.17 ± 0.02 IOD/area, P < 0.01) but not KS GAGs in HCC tissues. Further studies thereby were performed to investigate the expression and distribution of several CSPG components in HCC tissues, including aggrecan, versican, biglycan and decorin. Interestingly, there was a distinct distribution pattern for these CSPG components between HCC tissues and the normal tissues. Positive staining of aggrecan, biglycan and decorin was localized in hepatic membrane and/or pericellular matrix in normal liver tissues; however, their expression was mainly observed in the cytoplasm, cell membranes in hepatoma cells and/or pericellular matrix within HCC tissues. Semi-quantitative analysis indicated that there was a higher level of expression of aggrecan (0.43 ± 0.01 and 0.35 ± 0.03, P < 0.05), biglycan (0.32 ± 0.01 and 0.25 ± 0.01, P < 0.001) and decorin (0.29 ± 0.01 and 0.26 ± 0.01, P < 0.05) in HCC tissues compared with that in the normal liver tissues. Very weak versican positive staining was observed in hepatocytes near central vein in normal liver tissues; however there was an intensive versican distribution in fibrosis septa between the hepatoma nodules. Semi-quantitative analysis indicated that the positive rate of versican in hepatoma tissues from the HCC model group was much higher than that in the control group (33.61% and 21.28%, P < 0.05). There was no positive staining in lumican and keratocan, two major KSPGs, in either normal or HCC liver tissues.CONCLUSION: CSPGs play important roles in the onset and progression of HCC, and may provide potential therapeutic targets and clinical biomarkers for this prevalent tumor in humans.  相似文献   
72.
Identification of the Slow Conduction Zone in a Macroreentry. Background: Although idiopathic left ventricular tachycardia (ILVT) has been shown to possess a slow conduction zone (SCZ), the details of the electrophysiological and anatomic aspects are still not well understood. Objective: We hypothesized that the SCZ can be identified using a 3‐dimensional electroanatomic (EA) mapping system. Methods : Ten patients with ILVT were mapped using a 3‐dimensional electroanatomic (EA) mapping system. After a 3‐dimensional endocardial geometry of the left ventricular was created, the conduction system with left Purkinje potential (PP) and the SCZ with diastolic potential (DP) in LV were mapped during sinus rhythm (SR) and ventricular tachycardia (VT) and were tagged as special landmarks in the geometry. The electrophysiological and anatomic aspects of it were investigated. Results: EA mapping during SR and VT was successfully performed in 7 patients, during VT in 3 patients. The SCZ with DPs located at the inferoposterior septum was found in 7 patients during SR and all patients during VT. The length of the SCZ was 25.2 ± 2.3 mm with conduction velocity 0.08 ± 0.01 m/s. No differences in these parameters were found between patients during SR and VT (P > 0.05). An area with PP was found within the posterior septum. A crossover junction area with DP and PP was found in 7 patients during SR and VT. This area with DP and PP during SR coincided or were in proximity to such area during VT and radiofrequency ablation targeting the site within the area abolished VT in all patients. Conclusion: The ILVT substrate within the junction area of the SCZ and the posterior fascicular can be identified and can be used to guide the ablation of ILVT. (J Cardiovasc Electrophysiol, Vol. 23, pp. 840‐845, August 2012)  相似文献   
73.
74.
75.
76.
77.
BackgroundKupffer cells and related cytokines are thought to play a critical role in liver fibrosis; however, the role played by Kupffer cells in hepatitis B virus-related fibrogenesis is unknown.MethodsPrimary rat Kupffer cells were cultured with different titres of hepatitis B virus particles and the concentrations of transforming growth factor (TGF)-β1, interleukin (IL)-1, IL-6 and tumour necrosis factor (TNF)-α in the culture supernatant were measured every 24 h for 7 days. The mRNA and protein levels of these cytokines in Kupffer cells were also analysed using quantitative real-time polymerase chain reaction and western blotting, respectively.ResultsKupffer cells maintained normal morphology and function throughout the 7-day exposure to hepatitis B virus. The concentration of TGF-β1 secreted by hepatitis B virus-stimulated Kupffer cells (6 log IU/ml hepatitis B virus) increased 5.38- and 7.75-fold by Days 3 and 7, respectively (p < 0.01). Western blotting showed that TGF-β1 expression in Kupffer cells exposed to high titres of hepatitis B virus increased 1.80- and 2.42-fold by Days 3 and 7, respectively (p < 0.01). In contrast, Kupffer cell expression and secretion of pro-inflammatory cytokines (IL-6, IL-1 and TNF-α) was unchanged throughout the experiment.ConclusionHepatitis B virus preferentially stimulates Kupffer cells to produce the pro-fibrogenic/anti-inflammatory cytokine TGF-β1 rather than the pro-inflammatory cytokines IL-6, IL-1 and TNF-α. This may partly explain why overt liver fibrosis still presents in cases of chronic hepatitis B virus infection with minimal (or no) necro-inflammation.  相似文献   
78.
79.
正摘要目的本研究目的是在3 T MR上,采用最具可重复性兴趣区(ROI)的方法,阐明直肠癌组织病理学类型与扩散参数之间的相关性。方法113例病人行扩散峰度成像  相似文献   
80.
Clinical diagnosis and treatment of intraorbital wooden foreign bodies   总被引:1,自引:0,他引:1  
Purpose: The intraorbital wooden foreign body is often misdiagnosed or missed on computed tomography (CT) scan, due to the invisible or unclear images. The residual foreign bodies often occur during surgical removal. The clinical manifestations, imaging features and treatment of intraorbital wooden foreign bodies were discussed in this study. Method: We retrospectively analyzed 14 cases of intraorbital wooden foreign bodies managed at our hospital between January 2007 and May 2015. All patients underwent orbital CT examination before surgery, and surgery was performed under general anesthesia with orbital wound debridement and suture, as well as exploration and removal of wooden foreign bodies. Results: At first, 11 cases underwent removal of foreign bodies, including 1 case with incomplete removal and then receiving a secondary surgery. Foreign bodies were not found in three cases with preoperative misdiagnosis and orbital MRI found residual foreign bodies in the orbit. Operations were performed via primary wound approach in eight cases, conjunctival approach in two cases, and anterior orbitotomy in four cases. Postoperatively, one case was complicated with eye injuries, three cases with ocular muscle injuries, eight cases with visual loss, and eight cases with orbital abscess. The length of foreign bodies ranged from 1.8 cm to 11.0 cm. The maximum of four foreign bodies were removed at the same time. Conclusion: Because the imaging of orbital wooden foreign bodies is complex and varied, MRI should be combined when they are invisible on CT scan. At the same time injuries trajectory and clinical manifestations of patients should be taken into account. Surgical exploration should be extensive and thorough, and foreign bodies and orbital abscess must be cleared.  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