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   1774篇
  免费   100篇
  国内免费   15篇
耳鼻咽喉   8篇
儿科学   36篇
妇产科学   78篇
基础医学   182篇
口腔科学   31篇
临床医学   143篇
内科学   471篇
皮肤病学   29篇
神经病学   179篇
特种医学   44篇
外科学   231篇
综合类   4篇
预防医学   89篇
眼科学   16篇
药学   200篇
中国医学   7篇
肿瘤学   141篇
  2024年   2篇
  2023年   16篇
  2022年   37篇
  2021年   57篇
  2020年   33篇
  2019年   48篇
  2018年   54篇
  2017年   45篇
  2016年   49篇
  2015年   69篇
  2014年   73篇
  2013年   89篇
  2012年   148篇
  2011年   144篇
  2010年   75篇
  2009年   63篇
  2008年   107篇
  2007年   115篇
  2006年   108篇
  2005年   113篇
  2004年   78篇
  2003年   103篇
  2002年   79篇
  2001年   18篇
  2000年   20篇
  1999年   19篇
  1998年   17篇
  1997年   8篇
  1996年   11篇
  1995年   9篇
  1994年   4篇
  1993年   4篇
  1992年   15篇
  1991年   10篇
  1990年   4篇
  1989年   3篇
  1988年   8篇
  1987年   10篇
  1986年   6篇
  1985年   8篇
  1984年   3篇
  1983年   5篇
  1982年   1篇
  1964年   1篇
排序方式: 共有1889条查询结果,搜索用时 15 毫秒
31.
Cancer cells undergo genetic changes allowing their adaptation to environmental changes, thereby obtaining an advantage during the long metastatic route, disseminated of several changes in the surrounding environment. In particular, plasticity in cell motility, mainly due to epigenetic regulation of cancer cells by environmental insults, engage adaptive strategies aimed essentially to survive in hostile milieu, thereby escaping adverse sites. This review is focused on tumor microenvironment as a collection of structural and cellular elements promoting plasticity and adaptive programs. We analyze the role of extracellular matrix stiffness, hypoxia, nutrient deprivation, acidity, as well as different cell populations of tumor microenvironment.  相似文献   
32.
ObjectiveThe purpose of the present research was to compare the residual microbial load in Solo System microfiber mops with silver and in normal microfiber mops without silver to see whether those with the silver prevent bacterial proliferation and spread more effectively during normal cleaning operations.MethodsMops with and without silver were experimentally contaminated with suspension of Staphylococcus aureus ATCC 6538. The bioburden was evaluated by a filtering procedure according to UNI EN 1174 after contamination, after washing and after different times of impregnation in an alcohol-base detergent.Results and discussionThe results obtained lead to the conclusion that silver microfiber mop was significantly more effective in reducing bacterial load despite initial high level contamination (106-107 CFU/50 cm2). Indeed, after low temperature washing, the bacterial load was already completely eliminated while the mop without silver still presented relatively high levels of the microorganism (approximately 102 CFU/50 cm2) even after being soaked for 8 hours in a detergent/disinfectant.  相似文献   
33.

Background  

Thromboelastography is a technique that surveys the properties of viscoelastic blood clot. The purpose of this paper was to evaluate the hypercoagulability state and the effect of antithrombotic prophylaxis on thromboelastogram (TEG) results in bariatric surgery.  相似文献   
34.
AIMS: Treatment delay is a powerful predictor of survival in ST-elevation myocardial infarction (STEMI) patients undergoing primary percutaneous coronary intervention (PCI). We investigated effectiveness of pre-hospital diagnosis of STEMI with direct referral to PCI, alongside more conventional referral strategies. METHODS AND RESULTS: From January 2003 to December 2004, 658 STEMI patients were referred for primary PCI at our intervention laboratory. Three predefined referral routes were compared: (1) for patients within 90 min drive of the PCI centre, pre-hospital diagnosis and direct transportation (n=166), (2) diagnosis at the interventional hospital emergency department (n=316), (3) diagnosis at local hospitals before transportation (n = 176). Pre-hospital diagnosis was associated with more than 45 min reduction in treatment delay (P = 0.001). No significant difference in in-hospital mortality was apparent in the overall study population. In the cardiogenic shock subgroup (n = 80), pre-hospital diagnosis was associated with a two-thirds reduction in in-hospital mortality (P = 0.019); mortality was only 6.2% in shock patients who underwent PCI in < 2 h. CONCLUSION: This study shows that pre-hospital diagnosis can provide a reduction in primary PCI treatment delay, and suggests the hypothesis that this referral strategy might provide survival benefits to patients with cardiogenic shock.  相似文献   
35.
Introduction: Amyotrophic Lateral Sclerosis (ALS) is a progressive, incurable neurodegenerative disease that targets motoneurons. Cell-based therapies have generated widespread interest as a potential therapeutic approach but no conclusive results have yet been reported either from pre-clinical or clinical studies.

Areas covered: This is an integrated review of pre-clinical and clinical studies focused on the development of cell-based therapies for ALS. We analyze the biology of stem cell treatments and results obtained from pre-clinical models of ALS and examine the methods and the results obtained to date from clinical trials. We discuss scientific, clinical, and ethical issues and propose some directions for future studies.

Expert opinion: While data from individual studies are encouraging, stem-cell-based therapies do not yet represent a satisfactory, reliable clinical option. The field will critically benefit from the introduction of well-designed, randomized and reproducible, powered clinical trials. Comparative studies addressing key issues such as the nature, properties, and number of donor cells, the delivery mode and the selection of proper patient populations that may benefit the most from cell-based therapies are now of the essence. Multidisciplinary networks of experts should be established to empower effective translation of research into the clinic.  相似文献   

36.
Intramyocardial dissecting hematoma is an uncommon complication of myocardial infarction potentially leading to cardiac rupture. The aim of the present study was to investigate coronary reperfusion results, left ventricular (LV) function recovery and remodeling and clinical outcomes in patients with anterior STEMI complicated by intramyocardial hematoma. We prospectively studied 87 patients (mean age 59?±?10 years; 88% male) with anterior STEMI (42 with intramyocardial hematoma) in order to evaluate coronary reperfusion results, LV remodeling (≥15% increase in end-systolic volume) and clinical outcomes (cardiac death, non-fatal reinfarction, and hospitalization for congestive heart failure) at 24 months. Thrombolysis in myocardial infarction (TIMI) flow score and myocardial blush grade (MBG) were assessed both pre- and post-percutaneous coronary intervention (PCI) and speckle-tracking echocardiography was performed post PCI and at 6-month follow-up. Patients with hematoma had lower post-PCI TIMI score and MBG, higher heart rate, worse LV ejection fraction and longitudinal or rotational function than their counterparts. LV remodeling occurred in 33 (78.6%) patients with hematoma and 11 (24.4%) patients without (p?<?0.001). Independent predictors of LV remodeling were heart rate (p?=?0.018), MBG (p?=?0.036) and presence of hematoma (p?<?0.001). Hematoma (log-rank test, χ2?=?9.849; p?=?0.002) and LV remodeling (log-rank test, χ2?=?13.770; p?<?0.001) were associated to a higher rate of adverse events. Cox analysis identified LV remodeling as the only independent predictor of adverse events (hazard ratio?=?3.912; 95% confidence interval, 1.429–10.714; p?=?0.008). Intramyocardial dissecting hematoma complicating anterior STEMI is an independent determinant of LV remodeling and is associated to poor prognosis.  相似文献   
37.

Objective

To investigate whether oldest-old age (≥85y) is an independent predictor of exclusion from stroke rehabilitation.

Design

Retrospective cohort study.

Setting

Stroke unit (SU) of a tertiary hospital.

Participants

Elderly patients (N=1055; aged 65–74y, n=230; aged 75–84y, n=432; aged ≥85y, n=393) who, between 2009 and 2012, were admitted to the SU with acute stroke and evaluated by a multiprofessional team for access to rehabilitation. The study excluded patients for whom rehabilitation was unnecessary or inappropriate.

Interventions

Not applicable.

Main Outcome Measures

Access to an early mobilization (EM) protocol during SU stay and subsequent access to postacute rehabilitation after SU discharge. Analyses were adjusted for prestroke and stroke-related characteristics.

Results

32.2% of patients were excluded from EM. Multivariable-adjusted odds ratios (ORs) of EM exclusion were 1.30 (95% confidence interval [CI], .76–2.21) for ages 75 to 84 years and 2.07 (95% CI, 1.19–3.59) for ages ≥85 years compared with ages 65 to 74 years. Of 656 patients admitted to EM and who, at SU discharge, had not yet fully recovered their prestroke functional status, 18.4% were excluded from postacute rehabilitation. For patients able to walk unassisted at SU discharge, the probability of exclusion did not change across age groups. For patients unable to walk unassisted at SU discharge, ORs of exclusion from postacute rehabilitation were 3.74 (95% CI, 1.26–11.13) for ages 75 to 84 years and 9.15 (95% CI, 3.05–27.46) for ages ≥85 years compared with ages 65 to 74 years.

Conclusions

Oldest-old age is an independent predictor of exclusion from stroke rehabilitation.  相似文献   
38.
39.
Background Botulin toxin (BTX) has been proposed as a potential obesity treatment.Methods In a pilot study, the short-term efficacy and safety of BTX was assessed in eight subjects (four men, four women; median age, 46 years; range, 35–57 years) with severe obesity (median body mass index [BMI], 47.1 kg/m2; range 38.2–56.7 kg/m2) and multiple dietary treatment failures. In a single endoscopic session, 500 UI of BTX-A was injected in the gastric antral region.Results No clinically significant side effects were observed. In all patients, despite their not being on a specific diet, a reduction of body weight was observed at 1 month (median baseline weight, 124.4 kg vs 121.8 kg at 1 month; P < 0.05). Two treatment-unrelated dropouts were observed. At 4 months, three of the six patients had a further weight loss. The treatment effect was apparently independent of changes in hunger or satiety, or of changes in fasting and postprandial plasma ghrelin and serum leptin, thus suggesting a different pharmacological mechanism.Conclusions BTX-A treatment appears to be safe and well tolerated by obese patients, while its short-term efficacy varied widely.  相似文献   
40.
Somatic mutations of genes codifying for key regulatory proteins are the cause of different types of hormone-secreting adenomas. Natriuretic peptides (NP) are the strongest inhibitors of aldosterone secretion but aldosterone-secreting adenomas (aldosteronomas) are resistant to this inhibition and have reduced binding sites for NPs. The objective of this study was to sequence the entire coding region of the NP receptor type A (NPRA, codified by the Npr1 gene) to find loss-of-function somatic mutations. Total RNA was extracted from eight aldosteronomas and cDNA was synthesized. NPRA mRNA expression was evaluated by Northern blot analysis and compared with beta-actin mRNA as the housekeeping gene. Twelve primer couples were designed on the basis of the Npr1 gene organization to amplify, by PCR, all 22 coding exons of the gene. The two strands of amplified DNAs were purified and directly sequenced by automated capillary sequencer. NPRA mRNA expression did not differ among aldosteronomas. Npr1 open reading frame sequences obtained from eight aldosteronomas did not contain any mutation. The coding sequences of all 22 exons were identical in all samples and identical to published sequences. In the 3'-untranslated region (3'-UTR) a new length difference 3C/4C polymorphism was found at position 15 129 (three adenomas were 3C/4C and two were 3C/3C). Such a 3C/4C polymorphism was present in genomic DNA from 80 control subjects (25, 4C/4C; 40, 3C/4C; 15, 3C/3C). Mutations in the coding exons of the Npr1 gene do not appear to be a common cause of aldosteronomas. Moreover, the exons of Npr1 encoding for the translated portion of mRNA do not appear to be prone to polymorphisms. The polymorphism identified in the 3'-UTR might affect mRNA stability resulting in lower receptor synthesis, but it is not likely to confer a predisposition to the development of aldosteronomas.  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