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   348675篇
  免费   31544篇
  国内免费   24423篇
耳鼻咽喉   3157篇
儿科学   4062篇
妇产科学   5191篇
基础医学   41942篇
口腔科学   5882篇
临床医学   49067篇
内科学   52537篇
皮肤病学   3430篇
神经病学   19343篇
特种医学   12744篇
外国民族医学   218篇
外科学   34656篇
综合类   55347篇
现状与发展   82篇
一般理论   24篇
预防医学   22163篇
眼科学   10160篇
药学   35831篇
  370篇
中国医学   19090篇
肿瘤学   29346篇
  2024年   1059篇
  2023年   5291篇
  2022年   13713篇
  2021年   17249篇
  2020年   12842篇
  2019年   11451篇
  2018年   12077篇
  2017年   10639篇
  2016年   10009篇
  2015年   15378篇
  2014年   19199篇
  2013年   16759篇
  2012年   24889篇
  2011年   28071篇
  2010年   17648篇
  2009年   13713篇
  2008年   18646篇
  2007年   18696篇
  2006年   18631篇
  2005年   18038篇
  2004年   11716篇
  2003年   10777篇
  2002年   9240篇
  2001年   8169篇
  2000年   8788篇
  1999年   9395篇
  1998年   5692篇
  1997年   5704篇
  1996年   4470篇
  1995年   4036篇
  1994年   3314篇
  1993年   2149篇
  1992年   2895篇
  1991年   2455篇
  1990年   2149篇
  1989年   1899篇
  1988年   1587篇
  1987年   1379篇
  1986年   1121篇
  1985年   933篇
  1984年   537篇
  1983年   380篇
  1982年   248篇
  1981年   252篇
  1980年   195篇
  1979年   229篇
  1978年   87篇
  1977年   91篇
  1974年   107篇
  1973年   90篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
92.
93.
Malaria, one of the most striking, re-emerging infectious diseases caused by the genus Plasmodium, places a huge burden on global healthcare systems. A major challenge in the control and eradication of malaria is the continuous emergence of increasingly widespread drug-resistant malaria, creating an urgent need to develop novel antimalarial agents. Chalcone derivatives are ubiquitous in nature and have become indispensable units in medicinal chemistry applications due to their diverse biological profiles. Many chalcone derivatives demonstrate potential in vitro and in vivo antimalarial activity, so chalcone could be a useful template for the development of novel antimalarial agents. This review covers the recent development of chalcone hybrids as antimalarial agents. The critical aspects of the design and structure–activity relationship of these compounds are also discussed.  相似文献   
94.
BACKGROUND. The identification and treatment of individuals with tuberculosis (TB) is a global public health priority. Accurate diagnosis of pulmonary active TB (ATB) disease remains challenging and relies on extensive medical evaluation and detection of Mycobacterium tuberculosis (Mtb) in the patient’s sputum. Further, the response to treatment is monitored by sputum culture conversion, which takes several weeks for results. Here, we sought to identify blood-based host biomarkers associated with ATB and hypothesized that immune activation markers on Mtb-specific CD4+ T cells would be associated with Mtb load in vivo and could thus provide a gauge of Mtb infection.METHODS. Using polychromatic flow cytometry, we evaluated the expression of immune activation markers on Mtb-specific CD4+ T cells from individuals with asymptomatic latent Mtb infection (LTBI) and ATB as well as from ATB patients undergoing anti-TB treatment.RESULTS. Frequencies of Mtb-specific IFN-γ+CD4+ T cells that expressed immune activation markers CD38 and HLA-DR as well as intracellular proliferation marker Ki-67 were substantially higher in subjects with ATB compared with those with LTBI. These markers accurately classified ATB and LTBI status, with cutoff values of 18%, 60%, and 5% for CD38+IFN-γ+, HLA-DR+IFN-γ+, and Ki-67+IFN-γ+, respectively, with 100% specificity and greater than 96% sensitivity. These markers also distinguished individuals with untreated ATB from those who had successfully completed anti-TB treatment and correlated with decreasing mycobacterial loads during treatment.CONCLUSION. We have identified host blood-based biomarkers on Mtb-specific CD4+ T cells that discriminate between ATB and LTBI and provide a set of tools for monitoring treatment response and cure.TRIAL REGISTRATION. Registration is not required for observational studies.FUNDING. This study was funded by Emory University, the NIH, and the Yerkes National Primate Center.  相似文献   
95.
Microglia, the innate immune cells of the CNS, perform critical inflammatory and noninflammatory functions that maintain normal neural function. For example, microglia clear misfolded proteins, elaborate trophic factors, and regulate and terminate toxic inflammation. In Alzheimer’s disease (AD), however, beneficial microglial functions become impaired, accelerating synaptic and neuronal loss. Better understanding of the molecular mechanisms that contribute to microglial dysfunction is an important objective for identifying potential strategies to delay progression to AD. The inflammatory cyclooxygenase/prostaglandin E2 (COX/PGE2) pathway has been implicated in preclinical AD development, both in human epidemiology studies and in transgenic rodent models of AD. Here, we evaluated murine models that recapitulate microglial responses to Aβ peptides and determined that microglia-specific deletion of the gene encoding the PGE2 receptor EP2 restores microglial chemotaxis and Aβ clearance, suppresses toxic inflammation, increases cytoprotective insulin-like growth factor 1 (IGF1) signaling, and prevents synaptic injury and memory deficits. Our findings indicate that EP2 signaling suppresses beneficial microglia functions that falter during AD development and suggest that inhibition of the COX/PGE2/EP2 immune pathway has potential as a strategy to restore healthy microglial function and prevent progression to AD.  相似文献   
96.
97.
98.
苏州科技城医院坐落于苏州高新区太湖之滨,由苏州高新区政府投资新建,是一所集医疗、科研、康复、预防于一体的三级综合性公立医院。医院占地面积140亩,总建筑面积180000m~2,总投资额16亿,设计床位1200张。医院于2013年9月29日奠基,2014年12月28日主体封顶,2016年4月正式投入使用,比预定日期提前了将近1年!  相似文献   
99.
Objective To observe the clinical characteristics and prognosis of patients with rapidly progressive glomerulonephritis (RPGN) caused by lupus nephritis, antineutrophil cytoplasmic antibodies (ANCA)-associated vasculitis, or primary glomerulonephritis who were treated with peritoneal dialysis (PD) and then withdrew PD because of renal recovery. Methods Data of the above patients were retrospectively analyzed. The patients were diagnosed as RPGN and received PD therapy in Kidney Disease Center, the First Affiliated Hospital, College of Medicine, Zhejiang University from February 2009 to August 2018. The patients were divided into early withdrawal group (PD time≤183 days, n=24) and late withdrawal group (PD time>183 day, n=24). The differences of clinical characteristics between the two groups were compared. The cumulative incidence of adverse events in both groups was analyzed using Kaplan-Meier curves. Cox proportional hazards model was used to analyze the risk factors influencing the prognosis of patients. Results Forty-eight RPGN patients were included. The median time of maintaining PD was 178(76, 378) days. Compared with the late withdrawal group, the patients in early withdrawal group had lower levels of urine volume, serum albumin and parathyroid hormone, and lower rates of gross hematuria and hypertension at the beginning of PD, and received higher rates of methylprednisolone impulse, combined immunosuppressive agents, and hemodialysis or continuous renal replacement therapy (all P<0.05). At the time of PD withdrawal, the levels of serum creatinine, serum calcium, serum albumin and parathyroid hormone in the early withdrawal group were significantly lower than those in the late withdrawal group (all P<0.05). The Kaplan-Meier curves showed that there was no significant difference in the cumulative survival of patients in both groups (log-rank test χ2=3.485, P=0.062). Cox regression analysis revealed serum creatinine≥209 μmol/L at the time of PD withdrawal was an independent risk factor for poor prognosis (HR=5.253,95%CI 1.757-15.702, P=0.003). Conclusions PD can be used for RPGN patients caused by lupus nephritis, ANCA-associated vasculitis and primary nephritis. Serum creatinine≥209 μmol/L at the time of PD withdrawal is an independent risk factor for poor prognosis.  相似文献   
100.
Acid-suppressive drugs, including histamine-2 receptor antagonists (H2RAs) and proton pump inhibitors (PPIs), are common medications used for treating upper gastrointestinal tract disorders. However, acid-suppressive drugs have been reported to increase the risk of pneumonia in numerous disease populations. However, the relationship between acid-suppressive drugs and stroke-associated pneumonia (SAP) remains controversial.The purpose of this study was to investigate the association between acid-suppressive drug usage and pneumonia among patients with stroke by using a nationwide data set.A population-based cohort study was conducted using a data set from the Taiwanese National Health Insurance Research Database. Data on patients with new-onset stroke from 2010 to 2011 were collected. Patients with and without acid-suppressive drug usage were followed up to identify the occurrence of any type of pneumonia. We estimated the adjusted hazard ratios (HRs) by using the Cox proportional hazards model.The study cohort comprised 7965 patients with new-onset stroke. The incidence of pneumonia was 6.9% (552/7965) and more than 40% (225/552) of patients developed pneumonia within 3 months after an acute stroke. Acid-suppressive drug usage was an independent risk factor of pneumonia. The adjusted HR for the risk of pneumonia in patients with new-onset stroke using acid-suppressive drugs was 1.44 (95% confidence interval [CI] = 1.18–1.75, P < 0.01). Only PPI usage increased risk of chronic SAP (adjusted HR = 1.46, 95% CI = 1.04–2.05).Acid-suppressive drug usage was associated with a slightly increased risk of SAP. Physicians should exercise caution when prescribing acid-suppressive drugs to patients with stroke, particularly at the chronic stage.  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