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   568篇
  免费   31篇
  国内免费   7篇
儿科学   15篇
妇产科学   10篇
基础医学   106篇
口腔科学   7篇
临床医学   44篇
内科学   137篇
皮肤病学   19篇
神经病学   58篇
特种医学   1篇
外科学   87篇
综合类   2篇
预防医学   48篇
眼科学   3篇
药学   30篇
中国医学   1篇
肿瘤学   38篇
  2024年   2篇
  2023年   7篇
  2022年   20篇
  2021年   31篇
  2020年   18篇
  2019年   30篇
  2018年   25篇
  2017年   17篇
  2016年   14篇
  2015年   19篇
  2014年   28篇
  2013年   32篇
  2012年   71篇
  2011年   59篇
  2010年   21篇
  2009年   25篇
  2008年   28篇
  2007年   28篇
  2006年   29篇
  2005年   30篇
  2004年   23篇
  2003年   15篇
  2002年   13篇
  2001年   1篇
  2000年   2篇
  1999年   3篇
  1998年   5篇
  1997年   1篇
  1996年   1篇
  1995年   1篇
  1994年   1篇
  1993年   1篇
  1991年   1篇
  1987年   1篇
  1982年   2篇
  1973年   1篇
排序方式: 共有606条查询结果,搜索用时 0 毫秒
51.
Flavonoids are an important group of recognized antioxidants ubiquitous in fruits, vegetables and herbs. There are epidemiological evidences for the stroke-protecting capacity of flavonoids and while the neuroprotective power of complex extracts rich in flavonoids like those of Ginkgo biloba, green tea or lyophilized red wine have been demonstrated in several studies, neuroprotection by individual flavonoids has been poorly studiedin vivo. The neuroprotective capacity of individual flavonoids was studied in PC12 cells in culture and in a model of permanent focal ischemia (permanent Middle Cerebral Artery Occlusion — pMCAO). In thein vivo experiments, flavonoids were administered in lecithin preparations to facilitate the crossing of the blood brain barrier.  相似文献   
52.

Background

Neuroendocrine (NE) tumors commonly afflict patients with multiple endocrine neoplasia type 1 (MEN1). It is thought that patients with MEN1 have improved survival compared with individuals with analogous lesions. The role of metastasectomy of NE tumors in MEN1 patients is not clearly defined.

Methods

A review of MEN1 patients undergoing surgery for NE tumors from 1994 to 2010 at a single tertiary care center was performed. Tumor function, the extent of metastasis, R0 resection, and survival were analyzed.

Results

We identified 30 patients who underwent resection including synchronous and metachronous metastasectomy. Synchronous metastases were identified in 19 patients (63%), whereas 11 (37%) had metachronous disease. R0 resection was achieved in 93% of patients. Estimated 10-year survival is 86.4% (95% confidence interval, 60% to 100%) with no factors predictive of overall survival. The disease-free interval at 1, 5, and 10 years was 89%, 50%, and 19%, respectively, with recurrence occurring at a median of 5.4 years (95% confidence interval, 77.7% to 100%). Synchronous metastasis (P = .0072; hazard ratio [HR], 3.4) and nonfunctioning tumors (P = .014; HR, 3.3) were more likely to recur, whereas age (P = .09; HR, 1.5), gender (P = .49; HR, 1.3), and the site of metastasis (P = .81; HR, 1.1) did not influence recurrence.

Discussion

Patients with MEN1 benefit from resection of metastatic NE disease. Despite a high recurrence rate, survival and disease-free interval is favorable vs patients without MEN1.  相似文献   
53.
54.
The effects of 15?d polydextrose (16.7?g) consumption on energy intake (EI) and appetite feelings were investigated. Overweight adults consumed a polydextrose-bar or a control-bar matched in energy content as a midmorning snack for 15 consecutive days in a single-blind, randomised, crossover design. The two 15-d intervention periods were separated by a 15-d washout period. On the day 1 and the day 15 of each intervention period, energy intake (primary outcome) and appetite feelings (secondary outcome) were assessed. There were not significant main effects of the day, type of bar, or their interaction for EI (at lunchtime test meal, at rest of the day, or at total daily) or subjective feelings (hunger, desire to eat, fullness, and prospective food consumption) during the satiation and satiety periods. The results showed the consumption of polydextrose-bar during 15?d did not significantly affect energy intake and subjective feelings of appetite in overweight adults.  相似文献   
55.
Introduction: Mitochondrial-derived peptides (MDPs) are encoded within the mitochondrial genome. They signal within the cell or are released to act as autocrine/paracrine/endocrine cytoprotective factors playing a key role in the cellular stress response. The first reported and better characterized MDP is humanin (HN), which exerts robust protective effects against a myriad of cytotoxic stimuli in many cell types. These effects have led to the evaluation of HN and its analogs as therapeutic targets for several chronic diseases.

Areas covered: We describe the latest findings on the mechanism of action of HN and discuss the role of HN as therapeutic target for neurodegenerative and cardiovascular diseases, diabetes, male infertility, and cancer. Since HN can be detected in circulation, we also depict its value as a biomarker for these diseases.

Expert opinion: HN analogs and peptide mimetics have been developed over the last decade and show promising results in preclinical models of degenerative diseases. Local administration of gene therapy vectors that overexpress or silence endogenous HN could also hold therapeutic potential. Controversy on the role of HN in cancer progression and chemoresistance should be addressed before the translation of these therapeutic approaches.  相似文献   

56.
Controlled drug delivery aims to achieve an effective drug concentration in the action site for a desired period of time, while minimizing side effects. In this contribution, biodegradable poly(3-hydroxybutyrate) films were evaluated as a reservoir platform for dexamethasone controlled release. These systems were morphological and physicochemically characterized. In vitro release assays were performed for five different percentages of drug in the films and data were fitted by a mathematical model developed and validated by our research group. When the profiles were normalized, a single curve properly fitted all the experimental data. Using this unique curve, the dissolution efficiency (DE), the time to release a given amount of drug (tX%), and the mean dissolution time were calculated. Furthermore, the dissolution rate, the initial dissolution rate (a%) and the intrinsic dissolution rate were determined. The a% mean value was 1.968 × 10?2% released/min, t80% was about 14 days, and the DE was 59.6% at 14 days and 66.5% at 20 days. After 2 days, when approximately 40% of the drug was released, the dissolution rate decreased about 60% respect to the initial value. The poly(3-hydroxybutyrate) platforms behaved as an appropriate system to release and control the dexamethasone delivery, suggesting that they could be an alternative to improve drug therapy.  相似文献   
57.
Zika virus, influenza, and Ebola have called attention to the ways in which infectious disease outbreaks can severely – and at times uniquely – affect the health interests of pregnant women and their offspring. These examples also highlight the critical need to proactively consider pregnant women and their offspring in vaccine research and response efforts to combat emerging and re-emerging infectious diseases. Historically, pregnant women and their offspring have been largely excluded from research agendas and investment strategies for vaccines against epidemic threats, which in turn can lead to exclusion from future vaccine campaigns amidst outbreaks. This state of affairs is profoundly unjust to pregnant women and their offspring, and deeply problematic from the standpoint of public health. To ensure that the needs of pregnant women and their offspring are fairly addressed, new approaches to public health preparedness, vaccine research and development, and vaccine delivery are required. This Guidance offers 22 concrete recommendations that provide a roadmap for the ethically responsible, socially just, and respectful inclusion of the interests of pregnant women in the development and deployment of vaccines against emerging pathogens. The Guidance was developed by the Pregnancy Research Ethics for Vaccines, Epidemics, and New Technologies (PREVENT) Working Group – a multidisciplinary, international team of 17 experts specializing in bioethics, maternal immunization, maternal-fetal medicine, obstetrics, pediatrics, philosophy, public health, and vaccine research and policy – in consultation with a variety of external experts and stakeholders.  相似文献   
58.
59.
Basal forebrain cholinergic neurons are highly dependent on nerve growth factor (NGF) supply for the maintenance of their cholinergic phenotype as well as their cholinergic synaptic integrity. The precursor form of NGF, proNGF, abounds in the CNS and is highly elevated in Alzheimer’s disease. In order to obtain a deeper understanding of the NGF biology in the CNS, we have performed a series of ex vivo and in vivo investigations to elucidate the mechanisms of release, maturation and degradation of this neurotrophin. In this short review, we describe this NGF metabolic pathway, its significance for the maintenance of basal cholinergic neurons, and its dysregulation in Alzheimer’s disease. We are proposing that the conversion of proNGF to mature NGF occurs in the extracellular space by the coordinated action of zymogens, convertases, and endogenous regulators, which are released in the extracellular space in an activity-dependent fashion. We further discuss our findings of a diminished conversion of the NGF precursor molecule to its mature form in Alzheimer’s disease as well as an augmented degradation of mature NGF. These combined effects on NGF metabolism would explain the well-known cholinergic atrophy found in Alzheimer’s disease and would offer new therapeutic opportunities aimed at correcting the NGF dysmetabolism along with Aβ-induced inflammatory responses.  相似文献   
60.
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