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   5336篇
  免费   362篇
  国内免费   39篇
耳鼻咽喉   46篇
儿科学   105篇
妇产科学   73篇
基础医学   604篇
口腔科学   65篇
临床医学   511篇
内科学   1428篇
皮肤病学   96篇
神经病学   707篇
特种医学   174篇
外科学   923篇
综合类   6篇
一般理论   1篇
预防医学   234篇
眼科学   58篇
药学   407篇
中国医学   8篇
肿瘤学   291篇
  2024年   4篇
  2023年   49篇
  2022年   116篇
  2021年   209篇
  2020年   105篇
  2019年   165篇
  2018年   198篇
  2017年   137篇
  2016年   165篇
  2015年   162篇
  2014年   232篇
  2013年   281篇
  2012年   406篇
  2011年   396篇
  2010年   235篇
  2009年   232篇
  2008年   352篇
  2007年   340篇
  2006年   328篇
  2005年   346篇
  2004年   326篇
  2003年   275篇
  2002年   228篇
  2001年   32篇
  2000年   31篇
  1999年   32篇
  1998年   63篇
  1997年   32篇
  1996年   38篇
  1995年   26篇
  1994年   39篇
  1993年   19篇
  1992年   8篇
  1991年   12篇
  1990年   7篇
  1989年   20篇
  1988年   13篇
  1987年   10篇
  1986年   8篇
  1985年   7篇
  1984年   8篇
  1983年   10篇
  1982年   6篇
  1980年   4篇
  1979年   4篇
  1976年   4篇
  1975年   2篇
  1974年   2篇
  1970年   3篇
  1968年   3篇
排序方式: 共有5737条查询结果,搜索用时 31 毫秒
101.
OBJECTIVE: Acylated ghrelin, a gastric peptide, possesses a potent GH- but also significant ACTH/cortisol-releasing activity mediated by the activation of GH secretagogue receptors (GHS-R) at the hypothalamus-pituitary level. The physiological role of ghrelin in the control of somatotroph and corticotroph function is, however, largely unclear. Glucagon is known to induce a clear increase of GH, ACTH and cortisol levels in humans, at least after intramuscular administration. In fact, glucagon is considered to be a classical alternative to insulin-induced hypoglycaemia (ITT) for the combined evaluation of the function of GH and the hypothalamus-pituitary-adrenal (HPA) axis. We aimed to clarify whether ghrelin mediate the GH and corticotroph responses to intramuscular glucagon or ITT, which has recently been reported able to induce a surprising ghrelin decrease. SUBJECTS: To this aim we enrolled six normal young male subjects [age (mean +/- SD): 29.0 +/- 8.0 years, body mass index (BMI) 21.9 +/- 2.5 kg/m(2)]. DESIGN AND MEASUREMENTS: In all the subjects we studied ghrelin, GH, ACTH, cortisol and glucose levels after glucagon (GLU; 0.017 mg/kg intramuscularly), ITT (0.1 IU/kg insulin intravenously) or saline administration. RESULTS: Saline infusion was not followed by any significant variation in ghrelin, GH and glucose levels while ACTH and cortisol showed the expected spontaneous morning trend toward a decrease. GLU administration increased (P < 0.01) circulating GH, ACTH and cortisol as well as insulin and glucose levels. ITT induced an obvious increase (P < 0.01) of GH, ACTH and cortisol levels. The ITT-induced increases in GH and ACTH, but not cortisol, levels were higher (P < 0.01) than those after GLU. Circulating ghrelin levels were not modified by GLU. On the other hand, ghrelin levels underwent a transient reduction (P < 0.01) after insulin-induced hypoglycaemia. CONCLUSIONS: Ghrelin does not mediate the GH and ACTH responses to glucagon or to the ITT. In fact, ghrelin levels are not modified at all by glucagon and transiently decrease during the ITT. These findings support the assumption that ghrelin does not play a major role in the physiological control of somatotroph and corticotroph function.  相似文献   
102.
BACKGROUND/AIMS: The identification of metabolic and environmental predictors of excess body fat is still far from being achieved. The aim of this study was to evaluate whether respiratory quotient in non-obese women is a predictor of body weight changes after a 6-year follow-up period. METHODS: Forty-three non-obese healthy women participated in the study. Their baseline general characteristics were: age 40.5 +/- 12.8 years; height 159 +/- 7 cm; weight 61.8 +/- 10.1 kg, and body mass index (BMI) 24.4 +/- 3.8 kg/m2. At baseline basal metabolic rate and respiratory quotient were determined by indirect calorimetry, while weight and BMI were recorded at the first observation and after the 3- and 6-year follow-ups. RESULTS: At the first observation basal metabolic rate was 5,360 +/- 713 kJ/day and respiratory quotient 0.850 +/- 0.052. After 6 years, with weight changes equal to 1.4 +/- 4.5 kg, baseline respiratory quotient was a significant predictor (p < 0.05) of changes in body weight or BMI together with baseline BMI. CONCLUSIONS: This follow-up study confirms that a high respiratory quotient (measured on free diet) predisposes to weight gain, especially in women with the highest baseline respiratory quotient (above the 90th percentile of the distribution for this variable).  相似文献   
103.

Introduction and objectives

The PARIS score allows combined stratification of ischemic and hemorrhagic risk in patients with ischemic heart disease treated with coronary stenting and dual antiplatelet therapy (DAPT). Its usefulness in patients with acute coronary syndrome (ACS) treated with ticagrelor or prasugrel is unknown. We investigated this issue in an international registry.

Methods

Retrospective multicenter study with voluntary participation of 11 centers in 6 European countries. We studied 4310 patients with ACS discharged with DAPT with ticagrelor or prasugrel. Ischemic events were defined as stent thrombosis or spontaneous myocardial infarction, and hemorrhagic events as BARC (Bleeding Academic Research Consortium) type 3 or 5 bleeding. Discrimination and calibration were calculated for both PARIS scores (PARISischemic and PARIShemorrhagic). The ischemic-hemorrhagic net benefit was obtained by the difference between the predicted probabilities of ischemic and bleeding events.

Results

During a period of 17.2 ± 8.3 months, there were 80 ischemic events (1.9% per year) and 66 bleeding events (1.6% per year). PARISischemic and PARIShemorrhagic scores were associated with a risk of ischemic events (sHR, 1.27; 95%CI, 1.16-1.39) and bleeding events (sHR, 1.14; 95%CI, 1.01-1.30), respectively. The discrimination for ischemic events was modest (C index = 0.64) and was suboptimal for hemorrhagic events (C index = 0.56), whereas calibration was acceptable for both. The ischemic-hemorrhagic net benefit was negative (more hemorrhagic events) in patients at high hemorrhagic risk, and was positive (more ischemic events) in patients at high ischemic risk.

Conclusions

In patients with ACS treated with DAPT with ticagrelor or prasugrel, the PARIS model helps to properly evaluate the ischemic-hemorrhagic risk.  相似文献   
104.
Right ventricular (RV) evaluation represents one of the major clinical tasks in the follow-up of repaired tetralogy of Fallot patients (rToF) with pulmonary valve regurgitation, as both severe RV dilatation and dysfunction are key factors in defining the need of pulmonary valve replacement. The aim of our study was to report the diagnostic accuracy of echocardiography in the identification of rToF patients with severely dilated and/or depressed RV as compared to cardiac magnetic resonance (CMR). Among our patients with rToF, a subgroup of 95 (17.6?±?6.8 years; 60% male), who underwent right ventricular qualitative and quantitative evaluation with CMR following echocardiographic suspicion of severe dilation/dysfunction, were included in the analysis. When comparing echocardiographic RV functional parameters to CMR findings, we found no association between CMR-ejection fraction (EF) and either tricuspid annulus plane systolic excursion (TAPSe) nor tissue Doppler systolic tricuspid excursion velocity (all p?=?ns). In contrast RVFAC was strongly associated with CMR-EF (r?=?0.44; p?<?0.01) as well as to longitudinal components of RV mechanics including tissue Doppler s′ (r?=?0.40; p?<?0.01) and TAPSE (r?=?0.36; p?<?0.01). When comparing echocardiographic and CMR structural parameters of the RV, we found that CMR RV volume was strongly related to echocardiographic measurements of RV end diastolic area (from the 4 chamber apical view) and with proximal parasternal short axis right ventricle outflow-dimension. Accordingly a regression model was derived from multiple regression analysis, which allows a more accurate estimate of CMR RV volume from echocardiography (r2?=?0.59, p?<?0.001). Our study demonstrates a significant, although imperfect, correlation between echocardiographic and CMR RV functional and geometrical parameters. Combining echocardiographic measures of RV inflow and RV outflow, we deliver a simple formula to estimate CMR-RV volume, improving the echocardiographic accuracy in RV volume quantification.  相似文献   
105.
It has been suggested that initiatives to eradicate specific communicable diseases need to be informed by eradication investment cases to assess the feasibility, costs, and consequences of eradication compared with elimination or control.A methodological challenge of eradication investment cases is how to account for the ethical importance of the benefits, burdens, and distributions thereof that are salient in people’s experiences of the diseases and related interventions but are not assessed in traditional approaches to health and economic evaluation.We have offered a method of ethical analysis grounded in theories of social justice. We have described the method and its philosophical rationale and illustrated its use in application to eradication investment cases for lymphatic filariasis and onchocerciasis, 2 neglected tropical diseases that are candidates for eradication.The eradication of smallpox was a signature success of global public health in the 20th century, but it is an open and contentious question whether global eradication as opposed to regional elimination or control is warranted for other potentially eradicable infectious diseases.1–4 The box on page 630 provides our definitions of eradication, elimination, and control, as explained by Dowdle.4

Definitions of Eradication, Elimination, and Control

Eradication—the permanent reduction to zero of the worldwide incidence of infection caused by a specific agent as a result of deliberate efforts so that intervention measures are no longer needed.
Elimination—the reduction to zero of the incidence of infection caused by a specific agent in a defined geographical area as a result of deliberate efforts; continued measures to prevent reestablishment of transmission are required.
Control—the reduction of disease incidence, prevalence, morbidity, or mortality to a locally acceptable level as a result of deliberate efforts; continued intervention measures are required to maintain the reduction.
Open in a separate windowSource. Dowdle.4Global eradication efforts require vast resource commitments that must be locked in over long time frames, thereby imposing opportunity costs that require justification. For example, donors invested $10.0 billion in the Global Polio Eradication Initiative from 1988 through 2012, and the Global Polio Eradication Initiative’s 2013 to 2018 strategic plan calls for an additional $5.5 billion, totaling $15.5 billion over 30 years.5 The Global Polio Eradication Initiative has prepared an economic case estimating net benefits to date at $27.0 billion and arguing that completion of the eradication initiative would be more cost effective than are available alternatives.6 Ideally, with so much at stake, deliberations about coordinated global approaches to eradicable infectious diseases should be informed by prospective comparative assessment of the feasibility, costs, and consequences of control, elimination, and eradication. The same point of principle applies to other large-scale, long-term, and resource-intensive health programs, substituting the relevant scenarios for comparison.The eradication investment case (EIC) framework is a method for making such assessments to apply them to eradicable infectious diseases.7–11 Although traditional health and economic assessments are core components of EICs, leading architects of the EIC framework contend that EICs should also include “a narrative of the moral value of launching an eradication program” to “capture the value of intangible benefits and ensure consideration of benefits that are difficult to quantify.”9(p143) EICs lacking such ethical analyses may critically overvalue or undervalue eradication scenarios compared with elimination or control by failing to identify ethically important kinds of benefits, burdens, and distributions thereof. The need for such prospective ethical analysis is not unique to assessing disease eradication programs and arguably should be part of assessing and justifying other kinds of health programs.How can EICs account for the ethical importance of the benefits, burdens, and distributions thereof that are salient in people’s experience of particular diseases and disease-related interventions but not assessed in traditional health and economic evaluations? We have proposed a method of ethical analysis grounded in social justice to help EICs respond to this challenge in hopes that it may also prove useful as an approach to prospective ethical assessment for health programs concerned with noneradicable infectious diseases and noninfectious diseases. We have illustrated the proposed method through its application to lymphatic filariasis and onchocerciasis, 2 neglected tropical diseases considered amenable to eradication and for which EICs are currently being assembled.7  相似文献   
106.
107.
108.

Aim

We assessed the hepatic safety of novel oral anticoagulants (NOACs) analyzing the publicly available US-FDA adverse event reporting system (FAERS).

Methods

We extracted reports of drug-induced liver injury (DILI) associated with NOACs, including acute liver failure (ALF) events. Based on US marketing authorizations, we performed disproportionality analyses, calculating reporting odds ratios (RORs) with 95% confidence interval (CI), also to test for event- and drug-related competition bias, and case-by-case evaluation for concomitant medications.

Results

DILI reports represented 3.7% (n = 146) and 1.7% (n = 222) of all reports for rivaroxaban and dabigatran, respectively. No statistically significant association was found for dabigatran, in primary and secondary analyses. Disproportionality signals emerged for rivaroxaban in primary analysis (ALF: n = 25, ROR = 2.08, 95% CI 1.34, 3.08). In a large proportion of DILI reports concomitant hepatotoxic and/or interacting drugs were recorded: 42% and 37% (rivaroxaban and dabigatran, respectively), especially statins, paracetamol and amiodarone. Among ALF reports, fatal outcome occurred in 49% of cases (44% and 51%, rivaroxaban and dabigatran, respectively), whereas rapid onset of the event (<1 week) was detected in 46% of patients (47% and 44%, respectively).

Conclusions

The disproportionality signal for rivaroxaban calls for further comparative population-based studies to characterize and quantify the actual DILI risk of NOACs, taking into account drug- and patient-related risk factors. As DILI is unpredictable, our findings strengthen the role of (a) timely pharmacovigilance to detect post-marketing signals of DILI through FAERS and other data sources, (b) clinicians to assess early, on a case-by-case basis, the potential responsibility of NOACs when they diagnose a liver injury.  相似文献   
109.
There is concern that egg intake may increase blood glucose in patients with type 2 diabetes mellitus (T2DM). However, we have previously shown that eggs reduce inflammation in patients at risk for T2DM, including obese subjects and those with metabolic syndrome. Thus, we hypothesized that egg intake would not alter plasma glucose in T2DM patients when compared to oatmeal intake. Our primary endpoints for this clinical intervention were plasma glucose and the inflammatory markers tumor necrosis factor (TNF)-α and interleukin 6 (IL-6). As secondary endpoints, we evaluated additional parameters of glucose metabolism, dyslipidemias, oxidative stress and inflammation. Twenty-nine subjects, 35–65 years with glycosylated hemoglobin (HbA1c) values <9% were recruited and randomly allocated to consume isocaloric breakfasts containing either one egg/day or 40 g of oatmeal with 472 mL of lactose-free milk/day for five weeks. Following a three-week washout period, subjects were assigned to the alternate breakfast. At the end of each period, we measured all primary and secondary endpoints. Subjects completed four-day dietary recalls and one exercise questionnaire for each breakfast period. There were no significant differences in plasma glucose, our primary endpoint, plasma lipids, lipoprotein size or subfraction concentrations, insulin, HbA1c, apolipoprotein B, oxidized LDL or C-reactive protein. However, after adjusting for gender, age and body mass index, aspartate amino-transferase (AST) (p < 0.05) and tumor necrosis factor (TNF)-α (p < 0.01), one of our primary endpoints were significantly reduced during the egg period. These results suggest that compared to an oatmeal-based breakfast, eggs do not have any detrimental effects on lipoprotein or glucose metabolism in T2DM. In contrast, eggs reduce AST and TNF-α in this population characterized by chronic low-grade inflammation.  相似文献   
110.
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