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   4155篇
  免费   156篇
  国内免费   134篇
耳鼻咽喉   33篇
儿科学   83篇
妇产科学   60篇
基础医学   999篇
口腔科学   50篇
临床医学   304篇
内科学   700篇
皮肤病学   67篇
神经病学   319篇
特种医学   53篇
外科学   392篇
综合类   531篇
预防医学   239篇
眼科学   35篇
药学   310篇
中国医学   103篇
肿瘤学   167篇
  2023年   32篇
  2022年   78篇
  2021年   122篇
  2020年   101篇
  2019年   64篇
  2018年   72篇
  2017年   95篇
  2016年   125篇
  2015年   121篇
  2014年   223篇
  2013年   255篇
  2012年   205篇
  2011年   272篇
  2010年   239篇
  2009年   254篇
  2008年   260篇
  2007年   270篇
  2006年   279篇
  2005年   226篇
  2004年   208篇
  2003年   201篇
  2002年   122篇
  2001年   108篇
  2000年   85篇
  1999年   93篇
  1998年   56篇
  1997年   80篇
  1996年   56篇
  1995年   46篇
  1994年   37篇
  1993年   24篇
  1992年   13篇
  1991年   14篇
  1990年   5篇
  1989年   3篇
  1988年   1篇
排序方式: 共有4445条查询结果,搜索用时 15 毫秒
1.
2.
目的 探讨滤泡辅助性T(Tfh)细胞和半乳糖缺乏的IgA1(Gd-IgA1)在儿童过敏性紫癜(HSP)发病机制中的作用及两者之间的相关性。方法 选取初发HSP患儿36例,根据是否发生紫癜性肾炎(HSPN)分为HSPN组(11例)和非HSPN组(25例)。另选取15例门诊体检儿童作为健康对照组。采用流式细胞术检测外周血中Tfh细胞(CD4+CXCR5+ICOS+)比例。采用ELISA法检测外周血中IL-21、IL-6、血清IgA1、血清Gd-IgA1表达水平。采用Pearson相关分析法分析HSP组患儿血清Gd-IgA1浓度与Tfh细胞比例及其相关因子的相关性。结果 HSPN和非HSPN组患儿外周血Tfh细胞比例及IL-21、IL-6表达水平较健康对照组升高(P < 0.05),HSPN组上述指标较非HSPN组亦明显上升(P < 0.05)。HSPN和非HSPN组患儿血清中IgA1、Gd-IgA1表达水平较健康对照组升高(P < 0.05),HSPN组患儿血清IgA1和Gd-IgA1水平较非HSPN组亦明显升高(P < 0.05)。HSP组患儿血清Gd-IgA1水平与Tfh细胞比例及IL-21、IL-6水平均呈显著正相关关系(P < 0.05)。结论 Tfh细胞及其相关细胞因子和血清Gd-IgA1共同参与HSP/HSPN的发生。Tfh细胞可能介导了Gd-IgA1生成增加。  相似文献   
3.
Neutrophils constitute the major population of infiltrating leukocytes after stroke including intracerebral hemorrhage (ICH), and these cells may exhibit pro-inflammatory and anti-inflammatory phenotypes depending on the external stimuli. Here we constructed an experimental system to evaluate how the properties of neutrophils were influenced by the injured brain tissues. HL60 cells differentiated into neutrophils were added to the culture medium of neonatal rat cortico-striatal slices maintained at liquid–air interface. Thrombin was applied to the cultures to mimic the pathogenic events associated with ICH. HL60 cells responded to thrombin by increasing mRNA expression of pro-inflammatory IL-1β and anti-inflammatory IL-10 with a different time course. Co-presence of cortico-striatal slice cultures significantly enhanced IL-1β mRNA expression, whereas attenuated IL-10 mRNA expression, in HL60 cells. Toll-like receptor 4 (TLR4) agonist lipopolysaccharide synergistically enhanced IL-1β mRNA expression with thrombin, and TLR4 inhibitor TAK-242 abolished thrombin-induced IL-1β mRNA expression in the presence of slice cultures. On the other hand, thrombin-induced cell death in cortico-striatal cultures was attenuated by the presence of HL60 cells. This experimental system may provide a unique platform to elucidate complex cell-to-tissue interactions during ICH pathogenesis.  相似文献   
4.
COVID-19 emerges as a pandemic disease with high mortality. Development of effective prevention and treatment is an urgent need. We reviewed TH17 responses in patients with SARS-CoV-2 and proposed an FDA approved JAK2 inhibitor Fedratinib for reducing mortality of patients with TH17 type immune profiles.  相似文献   
5.
BackgroundAs an ongoing worldwide health issue, Coronavirus disease 2019 (COVID–19) has been causing serious complications, including pneumonia, acute respiratory distress syndrome (ARDS), and multi-organ failure. However, there is no decisive treatment approach available for this disorder, which is primarily attributed to the large amount of inflammatory cytokine production. We aimed to identify the effects of Nano-curcumin on the modulation of inflammatory cytokines in COVID-19 patients.MethodForty COVID-19 patients and 40 healthy controls were recruited and evaluated for inflammatory cytokine expression and secretion. Subsequently, COVID-19 patients were divided into two groups: 20 patients receiving Nano-curcumin and 20 patients as the placebo group. The mRNA expression and cytokine secretion levels of IL-1β, IL-6, TNF-α and IL‐18 were assessed by Real‐time PCR and ELISA, respectively.ResultOur primary results indicated that the mRNA expression and cytokine secretion of IL-1β, IL-6, TNF-α, and IL-18 were increased significantly in COVID-19 patients compared with healthy control group. After treatment with Nano-curcumin, a significant decrease in IL-6 expression and secretion in serum and in supernatant (P = 0.0003, 0.0038, and 0.0001, respectively) and IL-1β gene expression and secretion level in serum and supernatant (P = 0.0017, 0.0082, and 0.0041, respectively) was observed. However, IL-18 mRNA expression and TNF-α concentration were not influenced by Nano-curcumin.ConclusionNano-curcumin, as an anti-inflammatory herbal based agent, may be able to modulate the increased rate of inflammatory cytokines especially IL-1β and IL-6 mRNA expression and cytokine secretion in COVID-19 patients, which may cause an improvement in clinical manifestation and overall recovery.  相似文献   
6.
7.
When living organisms become sick as a result of a bacterial infection, a suite of brain-mediated responses occur, including fever, anorexia and sleepiness. Systemic administration of lipopolysaccharide (LPS), a common constituent of bacterial cell walls, increases body temperature and non-rapid eye movement (NREM) sleep in animals and induces the production of pro-inflammatory prostaglandins (PGs). PGE2 is the principal mediator of fever, and both PGE2 and PGD2 regulate sleep–wake behavior. The extent to which PGE2 and PGD2 are involved in the effect of LPS on NREM sleep remains to be clarified. Therefore, we examined LPS-induced changes in body temperature and NREM sleep in mice with nervous system-specific knockouts (KO) for the PGE2 receptors type EP3 or EP4, in mice with total body KO of microsomal PGE synthase-1 or the PGD2 receptor type DP, and in mice treated with the cyclooxygenase (COX) inhibitor meloxicam. We observed that LPS-induced NREM sleep was slightly attenuated in mice lacking EP4 receptors in the nervous system, but was not affected in any of the other KO mice or in mice pretreated with the COX inhibitor. These results suggest that the effect of LPS on NREM sleep is partially dependent on PGs and is likely mediated mainly by other pro-inflammatory substances. In addition, our data show that the main effect of LPS on body temperature is hypothermia in the absence of nervous system EP3 receptors or in the presence of a COX inhibitor.  相似文献   
8.

Background

Inflammation and infections have been associated with prostate cancer progression. We assessed whether elevated serum cytokines or T. vaginalis seropositivity at the time of diagnosis was associated with higher grade or lethal prostate cancer.

Patients and Methods

Men with localized or metastatic prostate cancer were included in this study. Cytokine serum levels including interleukin (IL)-1α, IL-1β, IL-2, IL-6, IL-8, monocyte chemotactic protein 1 (CCL-2), tumor necrosis factor α, and growth-regulated oncogene α (CXCL-1) using a multiplex enzyme-linked immunosorbent assay and T. vaginalis serology were measured in blood samples at diagnosis.

Results

A total of 324 patients were identified at time of localized disease and 118 at time of metastatic disease. Of the 189 patients with localized disease and clinical follow-up data (median, 73 months), 28 developed lethal disease. There was no association between circulating cytokine levels above median concentrations nor T. vaginalis seropositivity and risk of intermediate- to high-risk or lethal prostate cancer.

Conclusion

Higher levels of serum cytokine levels and T. vaginalis seropositivity at diagnosis are not associated with high-grade or lethal prostate cancer and do not aid risk stratification of localized prostate cancer.  相似文献   
9.
Coronavirus disease has unarguably been the largest pandemic of recent times. Over 150 million cases have occurred worldwide, and more than 3 million have succumbed to the disease. Cardiac manifestations can have varied presentations from an asymptomatic troponin rise to fulminant myocarditis. The pathogenesis of myocardial damage could be direct or indirect, including inflammation, coronary spasm, plaque rupture, and cytokine storm. Thromboembolism is also an important feature of cardiovascular affliction with both arterial and venous systems being affected. Hence, anticoagulation has also been a matter of debate. Fulminant myocarditis is the most severe form and can lead to circulatory shock with a high mortality. Management of cardiac patients with coronavirus disease 2019(COVID-19) infection is not considerably different from non-COVID-19 cardiovascular disease, but interaction between cardiovascular drugs and antiCOVID-19 therapy requires careful attention. More recently, vaccines have emerged as a ray of hope for the disease. But simultaneously, there have been reports of thromboembolism following vaccination. In this review, we discuss the various aspects of coronavirus disease affecting of heart and its management.  相似文献   
10.
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