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   46143篇
  免费   2178篇
  国内免费   383篇
耳鼻咽喉   489篇
儿科学   998篇
妇产科学   511篇
基础医学   6078篇
口腔科学   763篇
临床医学   2734篇
内科学   11894篇
皮肤病学   1068篇
神经病学   3478篇
特种医学   1870篇
外科学   8005篇
综合类   182篇
一般理论   6篇
预防医学   1166篇
眼科学   1016篇
药学   2949篇
中国医学   172篇
肿瘤学   5325篇
  2023年   216篇
  2022年   414篇
  2021年   930篇
  2020年   511篇
  2019年   683篇
  2018年   940篇
  2017年   741篇
  2016年   939篇
  2015年   1010篇
  2014年   1296篇
  2013年   1641篇
  2012年   2653篇
  2011年   2972篇
  2010年   1678篇
  2009年   1553篇
  2008年   2796篇
  2007年   3005篇
  2006年   3039篇
  2005年   3031篇
  2004年   3170篇
  2003年   3190篇
  2002年   3169篇
  2001年   604篇
  2000年   507篇
  1999年   661篇
  1998年   781篇
  1997年   673篇
  1996年   620篇
  1995年   523篇
  1994年   470篇
  1993年   507篇
  1992年   365篇
  1991年   335篇
  1990年   300篇
  1989年   286篇
  1988年   300篇
  1987年   225篇
  1986年   183篇
  1985年   193篇
  1984年   182篇
  1983年   158篇
  1982年   126篇
  1981年   165篇
  1980年   130篇
  1979年   105篇
  1978年   108篇
  1977年   85篇
  1976年   68篇
  1975年   56篇
  1974年   50篇
排序方式: 共有10000条查询结果,搜索用时 296 毫秒
991.
Clinical efficacy and safety of the therapeutic tool which directly removes LDL particles from circulation (LDL apheresis) have already been established in the treatment for refractory hypercholesterolemia in patients with familial hypercholesterolemia (FH). Two clinical studies with event-based assessment have demonstrated remarkably beneficial outcomes of long-term LDL apheresis using dextran sulfate cellulose columns plus adjunctive cholesterol-lowering drug therapy in the prevention of cardiovascular events in heterozygous FH with coronary artery disease. The results of several studies with angiographic and ultrasound-based assessment indicate a possible role for LDL apheresis in restructuring and stabilization of atherosclerotic lesions. These clinical improvements caused by LDL apheresis in heterozygous FH support the efficacy and importance of aggressive cholesterol-lowering therapy for secondary prevention of atherosclerotic cardiovascular disease in hypercholesterolemic patients.  相似文献   
992.
To determine the characteristic radiologic findings of inflammatory pseudotumor of the liver, various imagings of ten patients (11 lesions) with proven diagnoses of inflammatory pseudotumor were reviewed. Radiologic examinations, i.e., computed tomography (CT; 11 lesions), ultrasonography (11 lesions), magnetic resonance imaging (MRI; 6 lesions), angiography (10 lesions), CT during arterio-portography (CTAP; 3 lesions), and gallium-67 scans (9 lesions) were analyzed for their utility in diagnosis. No inflammatory pseudotumor showed a fibrous capsule around the lesion. Ten of the 11 lesions were poorly demarcated on most of the imagings, and all 11 lesions showed delayed and/or prolonged enhancement on CT or MRI. Arterio-portal shunting was observed in 4 lesions after contrast material administration on CT or angiography. Central lesions with suspiciously high fibrotic tissue content were demonstrated in 5 lesions on CT or MRI. Major vessels coursing in the lesions were demonstrated in 4 lesions by CT, MRI, and CTAP. Inflammatory pseudotumor of the liver should be included in the differential diagnosis in patients with hepatic masses, even if the patients are asymptomatic. If radiologic examinations suggest inflammatory pseudotumor, percutaneous biopsies should be performed so that unnecessary surgery can be avoided.  相似文献   
993.
Annals of Nuclear Medicine - Semi-quantitative positron emission tomography (PET) values, such as the maximum standardized uptake value (SUVmax), are widely used to identify malignant lesions and...  相似文献   
994.
Annals of Nuclear Medicine - Amyloid positron emission tomography (PET) can reliably detect senile plaques and fluorinated ligands are approved for clinical use. However, the clinical impact of...  相似文献   
995.
996.
Annals of Nuclear Medicine - Although previous studies have investigated age and gender effects on striatal subregional dopamine transporter (DaT) binding, these studies were mostly based on a...  相似文献   
997.
998.
OBJECTIVES: We examined whether the adenosine triphosphate (ATP)-sensitive potassium (K(ATP)) channel openers (KCOs) block myocardial hypertrophy and whether the 70-kDa S6 kinase (p70S6K) or extracellular signal-regulated kinase (ERK)-dependent pathway is involved. BACKGROUND: Long-term inhibition of nitric oxide (NO) synthesis induces cardiac hypertrophy independent of blood pressure, by increasing protein synthesis in vivo. The KCOs attenuate calcium overload and confer cardioprotection against ischemic stress, thereby preventing myocardial remodeling. METHODS: Twelve Wistar-Kyoto rat groups underwent eight weeks of the drug treatment in combination with the NO synthase inhibitor N(omega)-nitro-L-arginine methyl ester (L-NAME), the inactive isomer D(omega)-nitro-L-arginine methyl ester, KCOs (nicorandil, 3 and 10 mg/kg per day, or JTV-506, 0.3 mg/kg per day), or the K(ATP) channel blocker glibenclamide. The L-NAME was also used with hydralazine, the p70S6K inhibitor rapamycin, or the mitogen-activated protein kinase inhibitor PD98059. Finally, the left ventricular weight (LVW) to body weight (BW) ratio was quantified, followed by histologic examination and kinase assay. RESULTS: The L-NAME increased blood pressure and LVW/BW, as compared with the control agent. The KCOs and hydralazine equally cancelled the increase in blood pressure, whereas only KCOs blocked the increase in LVW/BW and myocardial hypertrophy induced by L-NAME. The L-NAME group showed both p70S6K and ERK activation in the myocardium (2.3-fold and 2.0-fold increases, respectively), as compared with the control group, which was not reversed by hydralazine. Selective inhibition of either p70S6K or ERK blocked myocardial hypertrophy. The KCOs prevented the increase in activity only of p70S6K. Glibenclamide reversed the effect of nicorandil in the presence of L-NAME. CONCLUSIONS: The KCOs modulate p70S6K, not ERK, to attenuate myocardial hypertrophy induced by long-term inhibition of NO synthesis in vivo.  相似文献   
999.
Miyashita N  Fukano H  Okimoto N  Hara H  Yoshida K  Niki Y  Matsushima T 《Chest》2002,121(6):1776-1781
STUDY OBJECTIVE: To investigate the clinical presentation of community-acquired Chlamydia pneumoniae pneumonia in adults. DESIGN: Prospective study. SETTING: Kawasaki Medical School Hospital, Kawasaki Medical School Kawasaki Hospital, and Kurashiki Daiichi Hospital in Japan. PARTICIPANTS: Forty patients with community-acquired pneumonia with C pneumoniae as the only pathogen identified admitted to three hospitals between April 1996 and March 2001 and their clinical presentations were compared to patients with Streptococcus pneumoniae and Mycoplasma pneumoniae pneumonia. MEASUREMENTS: The diagnosis of C pneumoniae infection was based on isolation and serologic testing of antibodies by the microimmunofluorescence test. RESULTS: The clinical presentations, except for shortness of breath, were similar for the three major etiologic agents. The mean temperature of C pneumoniae patients on hospital admission was 37.9 degrees C, which was lower than that of patients with S pneumoniae and M pneumoniae. The mean WBC count on hospital admission was lower in the patients with C pneumoniae (mean, 9,100/microL) than in those with S pneumoniae pneumonia but higher than in those with M pneumoniae pneumonia. No patients required respiratory support or admission to an ICU, and no deaths occurred among the C pneumoniae pneumonia patients. CONCLUSIONS: Our results indicate that C pneumoniae pneumonia as a single etiologic agent is mild and that the underlying conditions and clinical symptoms closely resemble those of S pneumoniae pneumonia. However, the physical examinations, laboratory findings, and prognostic factors of the C pneumoniae patients resembled those of patients with M pneumoniae pneumonia.  相似文献   
1000.
The discovery of the gene for cystic fibrosis (CF), the cystic fibrosis transmembrane conductance regulator (CFTR), brought about a new era in the study of this disease. Identification of the molecular target has yielded a flood of data that add to our understanding of the pathogenesis, diagnosis and treatment of CF. The CFTR protein is a cAMP-regulated Cl(-) channel with multiple functions in epithelial cells. In the exocrine pancreas the CFTR plays a key role in the apical Cl(-), HCO(3)(-), and water transport in duct cells. The severe loss of functions, caused by mutations of the CFTR gene, leads to pathological lesions of the pancreas. Over 1200 CFTR mutations and polymorphisms have been identified and their diversity may explain the high level of heterogeneity in the CF phenotype. Mutation analyses of the CFTR gene have revealed a spectrum of CFTR-related diseases that do not fit the classical CF picture but are associated with dysfunction of CFTR, such as chronic pancreatitis.  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