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   790篇
  免费   64篇
  国内免费   2篇
耳鼻咽喉   6篇
儿科学   19篇
妇产科学   17篇
基础医学   146篇
口腔科学   32篇
临床医学   63篇
内科学   145篇
皮肤病学   23篇
神经病学   89篇
特种医学   18篇
外科学   70篇
综合类   3篇
预防医学   48篇
眼科学   30篇
药学   59篇
中国医学   6篇
肿瘤学   82篇
  2024年   3篇
  2023年   9篇
  2022年   16篇
  2021年   40篇
  2020年   22篇
  2019年   25篇
  2018年   33篇
  2017年   28篇
  2016年   22篇
  2015年   35篇
  2014年   26篇
  2013年   57篇
  2012年   44篇
  2011年   76篇
  2010年   28篇
  2009年   33篇
  2008年   42篇
  2007年   47篇
  2006年   40篇
  2005年   41篇
  2004年   33篇
  2003年   42篇
  2002年   30篇
  2001年   4篇
  2000年   7篇
  1999年   4篇
  1998年   8篇
  1997年   5篇
  1996年   5篇
  1995年   3篇
  1994年   2篇
  1992年   2篇
  1991年   2篇
  1987年   2篇
  1983年   2篇
  1981年   1篇
  1979年   2篇
  1976年   1篇
  1974年   1篇
  1973年   2篇
  1972年   4篇
  1971年   2篇
  1970年   6篇
  1969年   2篇
  1968年   2篇
  1967年   2篇
  1966年   5篇
  1961年   1篇
  1959年   1篇
  1956年   1篇
排序方式: 共有856条查询结果,搜索用时 843 毫秒
81.
82.
We hypothesized that the brain-protective effect of hyperbaric oxygen (HBO) preconditioning in a transient global cerebral ischemia rat model is mediated by the inhibition of early apoptosis. One hundred ten male Sprague-Dawley (SD) rats (300-350 g body weight) were allocated to the sham group and three other groups with 10 min of four-vessel occlusion, untreated or preconditioned with either 3 or 5 hyperbaric oxygenations. HBO preconditioning improved neurobehavioral scores and reduced mortality, decreased ischemic cell change, reduced the number of early apoptotic cells and hampered a conversion of early to late apoptotic alterations. HBO preconditioning reduced the immunoreactivity of phosphorylated p38 in vulnerable neurons and increased the expression of brain derived neurotrophic factor (BDNF) in early stage post-ischemia. However, preconditioning with 3 HBO treatments proved less beneficial than with 5 HBO treatments. We conclude that HBO preconditioning may be neuroprotective by reducing early apoptosis and inhibition of the conversion of early to late apoptosis, possibly through an increase in brain BDNF level and the suppression of p38 activation.  相似文献   
83.
Pharmaceutical Research - The quality testing and approval procedure for most pharmaceutical products is a streamlined process with standardized procedures for the determination of critical quality...  相似文献   
84.
85.
The ansacarbamitocins are a new family of maytansinoids that are unusually substituted with a glucose subunit and two carbamate functional groups and exhibit modest activity against some agricultural fungal disease organisms. Ansacarbamitocins A-F ( 1- 6) all consist of the same macrocyclic core as the ansamitocins, with variation occurring on the glucose unit, while ansacarbamitocins A1 and B1 ( 7, 8) additionally lack the epoxide group on C-4 and C-5.  相似文献   
86.
The purpose of this study was to evaluate coil corrosion and the long-term outcome after peripheral vascular embolization therapy performed with tungsten coils. We studied 14 patients who received tungsten coils on an average of 26 months prior to follow-up. The protocol included plain radiography and contrast-enhanced magnetic resonance angiography to investigate corrosion of tungsten coils and recanalization of the embolized vessels. Whole blood, hair, and urine tungsten levels were assayed when available. Corrosion of tungsten coils was detected in 9 of 14 patients by plain radiography. No evidence of recanalization of the embolized vessel and no adverse clinical effects of tungsten resorption were detected. Blood levels of tungsten were elevated in 6 of 14 patients and urine levels of tungsten were elevated in all 12 patients tested. Tungsten coil corrosion and elevated tungsten levels in blood, hair, and urine were found in most patients, although no adverse clinical effects of tungsten resorption were detected. Since the overall effect of high tungsten blood levels remains unclear, its use as an implant should be avoided.  相似文献   
87.
88.
The efficacy and tolerance of a capsicum plaster in non-specific low back pain was investigated in a double-blind, randomised, placebo-controlled multicentre parallel group study. A total of 320 patients were randomly assigned to two groups of n=160 subjects treated by the active or the placebo plaster. The main outcome measures used were a compound pain subscore of the Arhus low back rating scale (continuous variable), and a response criterion of a reduction in pain subscore=30% from baseline to final assessment (secondary, non-continuous variable). In addition, the partial pain scores, disability and mobility restriction subscores, the total score of the Arhus low back rating scale, the global evaluation of efficacy by investigator and patient, adverse events, a patient questionnaire on use of the plaster, and an evaluation of tolerance by investigator and patient were obtained. After 3 weeks treatment with capsicum and placebo plaster respectively, the compound pain subscore was reduced by 42% (capsicum) and 31% (placebo) from values on entry. Responder rate was 67% versus 49% (p=0.002). The investigators rated efficacy as "excellent" or "good" by 74% and 36%; the patient's efficacy rating "symptomfree" or "improved" reached 82% and 50%. Adverse local drug reactions were found in 12 patients (7.5%) on capsicum and 5 (3.1%) on placebo. No systemic side-effects were observed. The superiority of the treatment of chronic non-specific low back pain with capsicum plaster compared to placebo was clinically relevant and highly statistically significant. The capsicum plaster offers a genuine alternative in the treatment of non-specific low back pain.  相似文献   
89.
Periannular extension of infective endocarditis   总被引:5,自引:0,他引:5  
OBJECTIVES: This prospective study was designed to assess the current clinical course, risk factors, microbiologic profile and echocardiographic findings of patients with left-sided endocarditis and perivalvular complications. BACKGROUND: Periannular complications worsen the prognosis of patients with endocarditis. The relation between these complications and the clinical and microbiologic data has not been clearly defined. METHODS: In this clinical cohort study, 211 patients with left-sided endocarditis, according to the Duke criteria, were prospectively recruited. All patients underwent conventional and transesophageal echocardiography. The mean follow-up interval was 151 days. RESULTS: Perivalvular complications were detected in 78 patients (37%). The incidence of periannular extension of infection in native and prosthetic valves was 29% and 55%, respectively. The presence of prosthesis (relative risk [RR] 1.88, 95% confidence interval [CI] 1.35 to 2.64) and previous endocarditis (RR 1.78, 95% CI 1.16 to 2.7) were the only pre-existing heart conditions associated with perivalvular complications. Aortic infection (RR 1.8, 95% CI 1.23 to 2.66) and the development of atrioventricular (AV) block (RR 2.55, 95% CI 1.91 to 3.41) were related with the existence of these complications. Coagulase-negative staphylococci were very common in patients with perivalvular complications (RR 1.77, 95% CI 1.21 to 2.59), and small vegetations were more frequent in these patients (RR l.45, 95% CI 0.95 to 2.22). An operation was more frequently performed in patients with perivalvular complications, but mortality was similar in patients with and without these complications. CONCLUSIONS: Aortic infection, prosthetic endocarditis, new AV block and coagulase-negative staphylococci were independent risk factors of periannular complications. The period between symptom onset and diagnosis, the incidence of pericardial effusion and persistent signs of infection were similar between patients with and without perivalvular complications. Patients with perivalvular complications did not demonstrate a difference in the presence or size of vegetations or the frequency of embolism. An operation was more frequently performed in these patients, but mortality was similar in both groups.  相似文献   
90.

The pathogenesis of chronic rhinosinusitis (CRS) remains unclear to date. The tissue remodeling in nasal polyps may be the result of inflammatory mediators and may involve epithelial–mesenchymal transition (EMT) and EMT-associated features such as cell motility in nasal epithelial cells (NECs). We determined whether NEC in nasal polyps of CRS already display features of EMT in vivo or respond with EMT to growth factor stimulation in vitro. Nasal polyp tissues expressed both epithelial and mesenchymal markers. Primary NEC from inferior turbinates and nasal polyps responded to the EMT-inducing agents transforming growth factor (TGF)-β1 and epidermal growth factor (EGF) with different expression patterns of EMT markers (E-cadherin, N-cadherin, Snail, Slug, Twist), however, only NEC from nasal polyps were susceptible to TGF-β1 and EGF-dependent cell migration. Our data suggest that a partial EMT is associated with the pathogenesis of nasal polyps in CRS patients. Furthermore, we show for the first time that epithelial cells from both nasal polyps and inferior turbinates were able to undergo an EMT-like process following exposure to TGF-β1 or EGF in vitro but that only NEC from nasal polyps responded with enhanced cell motility. Our data suggest that NEC from CRS patients have undergo partial EMT and that this process may be involved in the pathogenesis of CRS.

  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