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   823篇
  免费   46篇
  国内免费   39篇
耳鼻咽喉   1篇
儿科学   46篇
妇产科学   13篇
基础医学   68篇
口腔科学   26篇
临床医学   94篇
内科学   238篇
皮肤病学   6篇
神经病学   20篇
特种医学   166篇
外科学   76篇
综合类   20篇
预防医学   22篇
眼科学   7篇
药学   76篇
肿瘤学   29篇
  2021年   4篇
  2020年   3篇
  2019年   3篇
  2018年   11篇
  2017年   8篇
  2016年   4篇
  2015年   9篇
  2014年   19篇
  2013年   15篇
  2012年   14篇
  2011年   13篇
  2010年   23篇
  2009年   31篇
  2008年   14篇
  2007年   42篇
  2006年   19篇
  2005年   17篇
  2004年   19篇
  2003年   13篇
  2002年   23篇
  2001年   19篇
  2000年   11篇
  1999年   26篇
  1998年   54篇
  1997年   45篇
  1996年   42篇
  1995年   29篇
  1994年   27篇
  1993年   39篇
  1992年   19篇
  1991年   22篇
  1990年   13篇
  1989年   29篇
  1988年   25篇
  1987年   27篇
  1986年   15篇
  1985年   24篇
  1984年   15篇
  1983年   18篇
  1982年   15篇
  1981年   16篇
  1980年   21篇
  1979年   5篇
  1978年   10篇
  1977年   9篇
  1976年   8篇
  1975年   6篇
  1974年   2篇
  1973年   4篇
  1939年   2篇
排序方式: 共有908条查询结果,搜索用时 19 毫秒
51.
52.

Background

In support of professional practice, asynchronous communication between the patient and the provider is implemented separately or in combination with Internet-based self-management interventions. This interaction occurs primarily through electronic messaging or discussion boards. There is little evidence as to whether it is a useful tool for chronically ill patients to support their self-management and increase the effectiveness of interventions.

Objective

The aim of our study was to review the use and usability of patient-provider asynchronous communication for chronically ill patients and the effects of such communication on health behavior, health outcomes, and patient satisfaction.

Methods

A literature search was performed using PubMed and Embase. The quality of the articles was appraised according to the National Institute for Health and Clinical Excellence (NICE) criteria. The use and usability of the asynchronous communication was analyzed by examining the frequency of use and the number of users of the interventions with asynchronous communication, as well as of separate electronic messaging. The effectiveness of asynchronous communication was analyzed by examining effects on health behavior, health outcomes, and patient satisfaction.

Results

Patients’ knowledge concerning their chronic condition increased and they seemed to appreciate being able to communicate asynchronously with their providers. They not only had specific questions but also wanted to communicate about feeling ill. A decrease in visits to the physician was shown in two studies (P=.07, P=.07). Increases in self-management/self-efficacy for patients with back pain, dyspnea, and heart failure were found. Positive health outcomes were shown in 12 studies, where the clinical outcomes for diabetic patients (HbA1c level) and for asthmatic patients (forced expiratory volume [FEV]) improved. Physical symptoms improved in five studies. Five studies generated a variety of positive psychosocial outcomes.

Conclusions

The effect of asynchronous communication is not shown unequivocally in these studies. Patients seem to be interested in using email. Patients are willing to participate and are taking the initiative to discuss health issues with their providers. Additional testing of the effects of asynchronous communication on self-management in chronically ill patients is needed.  相似文献   
53.
There is much debate relating to possible abnormalities in respiratory control mechanisms in infants considered at increased risk for sudden infant death syndrome (SIDS). The P0.1 occlusion technique was used to assess the central respiratory response to hyperoxic hypercapnia during quiet sleep in 21 normal infants, 13 siblings of SIDS victims, and 17 infants with apparent life threatening events. The slope of P0.1 plotted against carbon dioxide concentration increased exponentially with age, independent of body weight in each group. Birth weight has a significant effect on slope with a lower weight predisposing to a lower slope. Siblings as a group had a significantly lower slope at any given age than normal infants, whereas the infants who had had apparent life threatening events were not significantly different from the controls. As intragroup variation in both siblings and control groups greatly exceeded the significant intergroup differences observed, the technique cannot identify individual infants as belonging to one or other group.  相似文献   
54.
Matrix metalloproteinases (MMP) and their inhibitors (TIMP) are central factors in the control of extracellular matrix turnover. They are important in normal physiology and also during a range of pathological states. Only recently has their role in cardiovascular disease been explored and their analysis through measurements in blood been studied. We have systematically identified clinical articles relevant to coronary artery disease from the last 10 years using MEDLINE. In this review we outline the structure, function and regulation of metalloproteinases and their key roles in angiogenesis, stable and unstable coronary artery disease. Metalloproteinases and their inhibitors are fundamental mediators of change in aging and atherosclerosis, the cell membrane, and in myocardial and vascular tissue. Defining their overall importance and understanding their complex interrelationships with pressure, thrombosis and local neural and hormonal tone will require detailed clinical study. The modulation of MMP and TIMP activity using drugs that affect the expression and function of these proteins will provide us with new ways to treat these serious and disabling diseases, and we explore potential mechanisms and treatments.  相似文献   
55.
BACKGROUND AND METHODS: Loop diuretic therapy is an essential part of chronic systolic heart failure (CH)F management, yet response to treatment can be variable. We analysed diuretic responsiveness in 39 stable patients with CHF in the community over 2 years. We measured serum ACE as a marker of adherence to ACE inhibitor therapy and urinary furosemide as a marker of diuretic adherence and action. Patients' clinical outcome was stable and not hospitalized (Group 0); alive but hospitalized (Group 1); or dead during follow up (Group 2). RESULTS: Prescribed furosemide dose was variable (range 20-370 mg generally once daily) and progressive dose increments were common. Failed furosemide adherence (defined as < 10% of a dose excreted in 24 h urine where normal average excretion = 50% of an oral dose) during static prescribed dosing was infrequent relative to all days of therapy; yet was equally common across all outcome groups. Furosemide non-adherence appeared to be independent of non-adherence with ACE inhibitor (as marked by serum ACE activity > 20 U l(-1)) treatment. Furosemide responsiveness (mm of sodium excreted per mg furosemide in urine) showed no relationship to prescribed dose and paradoxically tended to rise in patients with higher basal aldosterone concentrations. Furosemide responsiveness fell by outcome class despite increased dose. Within-patient responsiveness remained relatively constant although highly variable between individuals. CONCLUSIONS: Furosemide responsiveness varied greatly between individuals but was constant within an individual. Non-adherence with furosemide was less common among those who died and appeared to occur at different time points from non-adherence with ACE inhibitor treatment, which was slightly more common in all outcome groups. Patients who died were prescribed higher furosemide doses and had greater furosemide excretion yet had similar sodium excretion. The main factor in response to chronic furosemide therapy was intrarenal diuretic resistance. Gross non-adherence was less important.  相似文献   
56.
The alpha2 adrenergic receptor (α2-AR) antagonist yohimbine is a widely used tool for the study of anxiogenesis and stress-induced drug-seeking behavior. We previously demonstrated that yohimbine paradoxically depresses excitatory transmission in the bed nucleus of the stria terminalis (BNST), a region critical to the integration of stress and reward pathways, and produces an impairment of extinction of cocaine-conditioned place preference (cocaine-CPP) independent of α2-AR signaling. Recent studies show yohimbine-induced drug-seeking behavior is attenuated by orexin receptor 1 (OX1R) antagonists. Moreover, yohimbine-induced cocaine-seeking behavior is BNST-dependent. Here, we investigated yohimbine-orexin interactions. Our results demonstrate yohimbine-induced depression of excitatory transmission in the BNST is unaffected by alpha1-AR and corticotropin-releasing factor receptor-1 (CRFR1) antagonists, but is (1) blocked by OxR antagonists and (2) absent in brain slices from orexin knockout mice. Although the actions of yohimbine were not mimicked by the norepinephrine transporter blocker reboxetine, they were by exogenously applied orexin A. We find that, as with yohimbine, orexin A depression of excitatory transmission in BNST is OX1R–dependent. Finally, we find these ex vivo effects are paralleled in vivo, as yohimbine-induced impairment of cocaine-CPP extinction is blocked by a systemically administered OX1R antagonist. These data highlight a new mechanism for orexin on excitatory anxiety circuits and demonstrate that some of the actions of yohimbine may be directly dependent upon orexin signaling and independent of norepinephrine and CRF in the BNST.  相似文献   
57.
A variety of community-based epidemiological studies have suggested that 30-50% of patients with heart failure symptoms appear to have preserved left ventricular (LV) systolic function when assessed by echocardiography or similar techniques suggesting 'diastolic heart failure' (DHF) as its cause. The prognosis of these patients is characterised by morbidity and mortality similar to, but less overt than, patients with systolic dysfunction. However, rates of readmission for symptom control are broadly similar in patients with DHF or in those with systolic impairment. Thus, there are many similarities in the portrayal of both systolic and DHF but equally; there are also many key differences. Certainly, while there are several successful therapies for patients with systolic heart failure, the management of patients with DHF is poorly defined. In this review, the gaps in current knowledge and practice, which is creating this therapeutic void will be addressed.  相似文献   
58.
Ten years ago research showed that pro-smoking images were prevalent in British youth magazines, whereas there was little coverage of smoking and health. Since then there has been a great expansion in the number of youth magazines, and particularly those aimed at young men. Titles such as FHM and Loaded, which did not exist at the time of the previous research, are now market leaders. New qualitative and quantitative research has therefore been conducted to examine the prevalence and impact of smoking images in this revitalised youth style magazines market. This paper presents the findings of the qualitative element of this research, which examined British first year students' perceptions of the pro-smoking imagery found in the magazines and explored the relationship between this and their own smoking images and identities. The research found that: (a) this imagery was perceived to be, on the whole, attractive, sociable and reassuring; (b) that it supported young people's perceptions of smoking and reinforced their smoker identities; and (c) that it has the potential to be more powerful than advertising imagery.  相似文献   
59.
Serial polygraphic sleep studies were carried out in 86 index infants (33 'symptomatic', 24 siblings of infants with the sudden infant death syndrome (SIDS), 29 'near-miss' for SIDS) and 11 healthy controls. Brief (greater than or equal to 3 less than 6 sec) or prolonged (greater than or equal to 6 sec) obstructive apnoea was observed only in index caes, and coincided with symptoms due to associated illnesses (usually respiratory). Their prevalence was comparable in 'symptomatic' and 'near-miss' groups--39% and 35% respectively. Prolonged (greater than or equal to 20 sec) central apnoea was seen only in pre-term 'near-miss' infants. Dips in transcutaneous oxygen tension greater than or equal to 15 mmHg occurred during sleep in 17% of 'symptomatic' infants and 19% of 'near-miss' cases, usually in association with obstructive or central apnoea. Diminution or disappearance of these abnormalities following clinical recovery from 'minor' illnesses suggested that they were the result of such illnesses.  相似文献   
60.
报道25个N-甲基-N-(α-取代萘甲基)取代苄胺类化合物的合成及抗真菌活性。抑菌测试结果表明,目标化合物对于8种试验菌种均有不同程度的抑菌活性,化合物6,7,8,10,11和21等活性为naftifine的4~20倍,化合物8,10,11和21等活性为butenafine的2~10倍,化合物8,9,10,11和21等对Sporotrichumschenckii及Aspergillusfumigatus的活性为clotrimazole的8~15倍,化合物7,8,9和21等对Cryptoccocusneoformans亦表现出较高活性,MIC为0.31~1.25μg·ml-1。  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