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   14522篇
  免费   1865篇
  国内免费   231篇
耳鼻咽喉   98篇
儿科学   363篇
妇产科学   132篇
基础医学   2301篇
口腔科学   331篇
临床医学   1261篇
内科学   3791篇
皮肤病学   255篇
神经病学   646篇
特种医学   329篇
外国民族医学   3篇
外科学   1234篇
综合类   2241篇
预防医学   539篇
眼科学   157篇
药学   1384篇
中国医学   1048篇
肿瘤学   505篇
  2024年   6篇
  2023年   322篇
  2022年   722篇
  2021年   864篇
  2020年   979篇
  2019年   528篇
  2018年   498篇
  2017年   657篇
  2016年   558篇
  2015年   623篇
  2014年   1190篇
  2013年   1106篇
  2012年   840篇
  2011年   977篇
  2010年   759篇
  2009年   707篇
  2008年   770篇
  2007年   733篇
  2006年   628篇
  2005年   524篇
  2004年   459篇
  2003年   379篇
  2002年   297篇
  2001年   268篇
  2000年   236篇
  1999年   175篇
  1998年   129篇
  1997年   125篇
  1996年   112篇
  1995年   107篇
  1994年   81篇
  1993年   68篇
  1992年   49篇
  1991年   28篇
  1990年   19篇
  1989年   10篇
  1988年   16篇
  1987年   12篇
  1986年   9篇
  1985年   8篇
  1984年   12篇
  1983年   4篇
  1982年   7篇
  1981年   2篇
  1980年   3篇
  1979年   3篇
  1978年   2篇
  1976年   2篇
  1973年   2篇
  1971年   1篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
1.
2.
IntroductionInflammatory myofibroblastic tumors (IMFTs) are neoplastic lesions that are either benign or have low-grade malignancy potential. Although the etiopathogenesis is not entirely clear, many factors play a role in their development, including trauma, autoimmune disorders, and infectious and inflammatory processes. However, IMFTs caused by Actinomyces spp. infection are rare, with a limited number of cases reported in the literature.Presentation of caseA 30-year-old woman was admitted to our clinic with abdominal pain and a palpable abdominal mass. Contrast-enhanced computed tomography revealed a tumoral lesion (11 × 10 × 7 cm) in the right colon. A right hemicolectomy and ileocolic anastomosis were performed, during which almost complete obstruction of the lumen by the 7.5 × 7.0 × 5.0 cm tumor was observed. Histopathology and immunohistochemical findings revealed that the tumor was consistent with an IMFT that developed from an Actinomyces infection. The patient was then placed on amoxicillin and doxycycline therapy.ConclusionThis case demonstrates that the development of IMFT secondary to actinomycosis is difficult to predict in the preoperative period. Once an exact diagnosis is confirmed by histopathologic examination, affected patients should receive prolonged antibiotherapy.  相似文献   
3.
目的 探讨饮用不同浓度的葡聚糖硫酸钠(dextran sulfate sodium, DSS)对于建立小鼠炎症性肠病(inflammatory bowel disease, IBD)模型及其致病相关免疫因子表达的影响。方法 雄性C57BL/6J小鼠随机分为对照组和不同浓度的DSS饮用组(3%、5%、7%)。观察小鼠的大便性状,体重和生存时间。饮用后的第6天处死各组小鼠,观察结肠大体形态并评分;取病变处进行石蜡包埋病理切片,苏木素伊红染色并进行病理组织学评分;定量PCR检测各组脾细胞免疫因子表达情况。结果 饮用3%、5%、7%浓度DSS的小鼠在第6天均有不同程度溃疡形成,成模率随着DSS浓度提升而增加,但是小鼠死亡率也相应增加。定量PCR结果表明促炎因子(TNF-α、IFN-γ和IL-17A)的表达水平与DSS浓度成正相关,而抑炎因子(IL-4和IL-10)以及调节性T细胞相关的转录因子Foxp3的表达水平与DSS浓度成负相关关系。结论 给予小鼠5%浓度的DSS溶液饮用有助于高效经济地建立小鼠IBD模型,为进一步研究IBD的发病机理、生物学特性、干预因素等打下了重要基础。  相似文献   
4.
The purpose of this study was to examine the toxicological effects of nickel chloride (NiCl2; 300, 600, and 900 mg kg?1 diet) on the cytokine mRNA expression and protein levels in the intestinal mucosa and cecal tonsil, and on the ileac and cecal tonsil T cells in broilers by the methods of qRT‐PCR, flow cytometry and ELISA for 42 days. Results showed that the IL‐2, IL‐6, IL‐10, IL‐17, IFN‐γ, and TNF‐α (LITAF) cytokine mRNA expression and protein levels were lower (P < 0.05 or P < 0.01) and the percentages of T‐cell subsets were also lower in the 300, 600, and 900 mg kg?1 groups than in the control group. It was concluded that dietary NiCl2 in excess of 300 mg kg?1 could reduce cytokine mRNA expression and protein levels in the intestinal mucosa and cecal tonsil, and the percentages of ileac and cecal tonsil T‐cell subsets. Decreasing in cytokine mRNA expression and protein levels of intestinal mucosa and cecal tonsil induced by NiCl2 was closely related to the reduction of T‐cell population. Thus, the abnormal expression of these cytokines impacts the intestinal mucosal immune function by the pathways of reducing of lymphocyte population and activation. Also, this study first proved that NiCl2 at higher levels has the toxicological effects on intestinal mucosal immunity. © 2014 Wiley Periodicals, Inc. Environ Toxicol 30: 1309–1321, 2015.  相似文献   
5.
Both Gram‐positive and Gram‐negative pathogens or pathogen‐derived components, such as staphylococcal enterotoxins (SEs) and endotoxin (LPS) exposure, activate MyD88‐mediated pro‐inflammatory cellular immunity for host defense. However, dysregulated MyD88‐mediated signaling triggers exaggerated immune response that often leads to toxic shock and death. Previously, we reported a small molecule compound 1 mimicking BB‐loop structure of MyD88 was capable of inhibiting pro‐inflammatory response to SEB exposure in mice. In this study, we designed a dimeric structure compound 4210 covalently linked with compound 1 by a non‐polar cyclohexane linker which strongly inhibited the production of pro‐inflammatory cytokines in human primary cells to SEB (IC50 1–50 μm ) or LPS extracted from Francisella tularensis, Escherichia coli, or Burkholderia mallei (IC50 10–200 μm ). Consistent with cytokine inhibition, in a ligand‐induced cell‐based reporter assay, compound 4210 inhibited Burkholderia mallei or LPS‐induced MyD88‐mediated NF‐kB‐dependent expression of reporter activity (IC50 10–30 μm ). Furthermore, results from a newly expressed MyD88 revealed that 4210 inhibited MyD88 dimer formation which is critical for pro‐inflammatory signaling. Importantly, a single administration of compound 4210 in mice showed complete protection from lethal toxin challenge. Collectively, these results demonstrated that compound 4210 inhibits toxin‐induced inflated pro‐inflammatory immune signaling, thus displays a potential bacterial toxin therapeutic.  相似文献   
6.
7.
8.
A 9‐year‐old girl developed influenza A H1N1 pdm09‐associated myocarditis and pericarditis 2 days after starting zanamivir therapy. The virus was detected in the respiratory tract but not in the serum or pericardial effusion. The virus sampled from the respiratory tract had normal susceptibility to neuraminidase inhibitors. Although no differences in interferon‐γ, interleukin (IL)‐1β, and tumor necrosis factor‐α were observed between the plasma and pericardial effusion, some inflammatory cytokines or chemokines (IL‐6 and IL‐8) and vascular endothelial growth factor were remarkably elevated in the pericardial effusion compared with the plasma. This suggested that the influenza virus, after infecting the respiratory tract, affected the myocardium, causing myocarditis to gradually develop, which might have been followed by an autoreactive pericarditis causing increased pericardial effusion. Therefore, influenza‐associated myocarditis should be considered when influenza patients have respiratory and cardiac involvement, even during treatment with a neuraminidase inhibitor.  相似文献   
9.
雌激素抑制大鼠肝癌肺转移机制研究   总被引:1,自引:0,他引:1  
王永仓  许戈良  赵旭辉  魏忠  樊平  戴寅  谢钊  刘巧玉 《安徽医学》2015,36(12):1439-1441
目的探讨雌激素对大鼠肝癌肺转移形成的影响及其可能的机制。方法将雌性大鼠随机分为切除卵巢组、对照组、假手术组和去卵巢后加雌激素组,建立大鼠肝癌模型。诱癌20周后观察肿瘤发生、肺转移的情况;免疫组织化学法检测4组成瘤大鼠肝癌组织中雌激素受体α(ERα)、磷酸化雌激素受体α(P-ERα)、肝细胞生长因子(HGF)和白介素6(IL-6)的表达;半定量逆转录聚合酶链反应法检测 ERα、HGF 及 IL-6的 mRNA 水平。结果切除卵巢组大鼠肝癌肺转移发生率明显高于其他3组(P <0.05);大鼠肝癌肺转移发生率越高,肝癌组织中 HGF、IL-6的蛋白及分子水平表达越高(P <0.05),而 ERα的蛋白及分子水平表达越低(P <0.05)。结论雌激素可能通过下调 HGF 和 IL-6的表达来抑制肝癌肺转移的发生。  相似文献   
10.
目的:探讨痰热清能否减轻合并COPD肺癌患者术后炎性反应和肺损伤的程度。方法:选择39例合并COPD肺癌患者(痰热瘀肺型),随机分为被试组18例和对照组21例。所有患者行胸腔镜辅助下小切口手术。对照组用西医常规治疗,被试组加用痰热清注射液。在术前1天(T1)、术后第1天(T2)、第3天(T3)、第7天(T4)采集血清标本,测定两组血清中TNF-α、IL-6、IL-8和IL-10的浓度。结果:在T1、T2时间,两组患者体内TNF-α、IL-6、IL-8和IL-10水平比较无显著性差异(P>0.05);在T3时间,被试组患者体内TNF-α、IL-6和IL-8水平低于对照组,差异具有统计学意义(P<0.05),被试组患者体内IL-10水平高于对照组,差异具有统计学意义(P<0.05);在T4时间,被试组患者体内TNF-α、IL-6和IL-8水平低于对照组,差异具有统计学意义(P<0.05);两组患者在T3、T4时间TNF-α、IL-6、IL-8水平逐渐下降,与T2时间水平比较及相互比较,差异具有统计学意义(P<0.05)。结论:痰热清注射液能减少合并COPD肺癌围手术期间炎性细胞因子的释放,增加抗炎因子生成,从而减轻炎性反应程度,减轻肺脏损伤,保护肺功能。  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