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   2549篇
  免费   199篇
  国内免费   10篇
耳鼻咽喉   6篇
儿科学   84篇
妇产科学   220篇
基础医学   346篇
口腔科学   43篇
临床医学   294篇
内科学   436篇
皮肤病学   101篇
神经病学   144篇
特种医学   145篇
外科学   354篇
综合类   43篇
一般理论   3篇
预防医学   278篇
眼科学   24篇
药学   167篇
肿瘤学   70篇
  2021年   21篇
  2020年   21篇
  2019年   23篇
  2018年   29篇
  2017年   30篇
  2016年   25篇
  2015年   30篇
  2014年   56篇
  2013年   94篇
  2012年   123篇
  2011年   137篇
  2010年   62篇
  2009年   81篇
  2008年   106篇
  2007年   105篇
  2006年   114篇
  2005年   91篇
  2004年   92篇
  2003年   84篇
  2002年   51篇
  2001年   87篇
  2000年   74篇
  1999年   66篇
  1998年   58篇
  1997年   48篇
  1996年   57篇
  1995年   43篇
  1994年   40篇
  1993年   24篇
  1992年   58篇
  1991年   63篇
  1990年   46篇
  1989年   61篇
  1988年   66篇
  1987年   55篇
  1986年   58篇
  1985年   53篇
  1984年   45篇
  1983年   31篇
  1982年   20篇
  1981年   18篇
  1980年   17篇
  1979年   17篇
  1978年   29篇
  1977年   20篇
  1976年   19篇
  1975年   22篇
  1974年   27篇
  1973年   19篇
  1966年   19篇
排序方式: 共有2758条查询结果,搜索用时 10 毫秒
61.
Background: American Indians and Alaska Natives (AI/ANs) experience significant disparities in health status and access to care. Furthermore, only limited data are available on substance use, mental health disorders, and treatment needs for this population. Addressing such disparities and developing culturally relevant, effective interventions for AI/AN communities require participatory research. Objectives and Methods: The Western States Node of the National Institute on Drug Abuse Clinical Trials Network partnered with two American Indian substance abuse treatment programs: an urban health center and a reservation-based program to assess client characteristics, drug use patterns, and treatment needs. Data collected by staff members at the respective programs from urban (n = 74) and reservation (n = 121) clients were compared. Additional sub-analysis examined patients reporting regular opioid use and mood disorders. Results: Findings indicate that urban clients were more likely to report employment problems, polysubstance use, and a history of abuse. Reservation-based clients reported having more severe medical problems and a greater prevalence of psychiatric problems. Clients who were regular opioid users were more likely to report having a chronic medical condition, suicidal thoughts, suicide attempts, polysubstance abuse, and IV drug use. Clients who reported a history of depression had twice as many lifetime hospitalizations and more than five times as many days with medical problems. Conclusions: Findings from this project provide information about the patterns of substance abuse and the importance of comprehensive assessments of trauma and comorbid conditions. Results point to the need for integrative coordinated care and auxiliary services for AI/AN clients seeking treatment for substance use disorders.  相似文献   
62.

Background

More data on the risk factors and outcomes after Staphylococcus aureus infections in liver transplantation are needed.

Methods

Liver recipients with S. aureus infections (cases) were retrospectively identified and compared to gender-, age-, and transplant type-matched (1:2) non-S. aureus-infected controls. Risk factors associated with S. aureus infections were identified by conditional logistic regression analysis.

Results

We evaluated 51 patients (median age 52?years). First S. aureus infections developed at a median time of 29?days after transplantation, with 52.94% of them in the first month; 88.24% were nosocomial, 41.18% were polymicrobial, and 47.06% were caused by methicillin-resistant S. aureus (MRSA). Surgical site infections represented 58.82% and bacteremia 23.53%. By univariate analysis, patients with S. aureus infections were intubated more frequently (odds ratio [OR] 26.92, 95% confidence interval [CI] 3.23?C3,504.15, p?=?0.0006), had a central line (OR 11.69, 95% CI 1.42?C95.9, p?=?0.02), or recent surgery (OR 26.92, 95% CI 3.23?C3,504.15, p?=?0.0006) compared with controls. By multivariate analysis, subjects who underwent surgery within 2?weeks prior to infection had a 26.9 times higher risk of developing S. aureus infection (95% CI 3.23?C3,504.15, p?=?0.0006); these results were adjusted for matched criteria. S. aureus infections did not affect graft or patient survival, but the study was not powered for such outcomes.

Conclusion

Only recent surgical procedure was found to be a significant independent risk factor for S. aureus infections after liver transplantation.  相似文献   
63.
64.

Background

Onchocerciasis has been implicated in the pathogenesis of epilepsy. The debate on a potential causal relationship between Onchocerca volvulus and epilepsy has taken a new direction in the light of the most recent epidemic of nodding syndrome.

Objective

To document MRI changes in people with different types of epilepsy and investigate whether there is an association with O. volvulus infection.

Methods

In a prospective study in southern Tanzania, an area endemic for O. volvulus with a high prevalence of epilepsy and nodding syndrome, we performed MRI on 32 people with epilepsy, 12 of which suffered from nodding syndrome. Polymerase chain reaction (PCR) of O. volvulus was performed in skin and CSF.

Results

The most frequent abnormalities seen on MRI was atrophy (twelve patients (37.5%)) followed by intraparenchymal pathologies such as changes in the hippocampus (nine patients (28.1%)), gliotic lesions (six patients (18.8%)) and subcortical signal abnormalities (three patients (9.4%)). There was an overall trend towards an association of intraparenchymal cerebral pathologies and infection with O. volvulus based on skin PCR (Fisher''s Exact Test p=0.067) which was most pronounced in children and adolescents with nodding syndrome compared to those with other types of epilepsy (Fisher''s Exact Test, p=0.083). Contrary to skin PCR results, PCR of CSF was negative in all patients.

Conclusion

The observed trend towards an association of intraparenchymal cerebral pathological results on MRI and a positive skin PCR for O. volvulus despite negative PCR of CSF is intriguing and deserves further attention.  相似文献   
65.
A non‐synonymous, single nucleotide polymorphism (SNP) in the gene coding for steroid 5‐α‐reductase type 2 (SRD5A2) is associated with reduced conversion of testosterone to dihydrotestosterone (DHT). Because SRD5A2 participates in the regulation of testosterone and cortisol metabolism, hormones shown to be dysregulated in patients with PTSD, we examined whether the V89L variant (rs523349) influences risk for post‐traumatic stress disorder (PTSD). Study participants (N = 1,443) were traumatized African‐American patients of low socioeconomic status with high rates of lifetime trauma exposure recruited from the primary care clinics of a large, urban hospital. PTSD symptoms were measured with the post‐traumatic stress symptom scale (PSS). Subjects were genotyped for the V89L variant (rs523349) of SRD5A2. We initially found a significant sex‐dependent effect of genotype in male but not female subjects on symptoms. Associations with PTSD symptoms were confirmed using a separate internal replication sample with identical methods of data analysis, followed by pooled analysis of the combined samples (N = 1,443, sex × genotype interaction P < 0.002; males: n = 536, P < 0.001). These data support the hypothesis that functional variation within SRD5A2 influences, in a sex‐specific way, the severity of post‐traumatic stress symptoms and risk for diagnosis of PTSD. © 2013 Wiley Periodicals, Inc.  相似文献   
66.
This systematic review was conducted to determine the effects of self-help interactive computer-based interventions (ICBIs) for sexual health promotion. We searched 40 databases for randomized controlled trials (RCTs) of computer-based interventions, defining 'interactive' as programmes that require contributions from users to produce personally relevant material. We conducted searches and analysed data using Cochrane Collaboration methods. Results of RCTs were pooled using a random-effects model with standardized mean differences for continuous outcomes and odds ratios (ORs) for binary outcomes, with heterogeneity assessed using the I(2) statistic. We identified 15 RCTs of ICBIs (3917 participants). Comparing ICBIs to minimal interventions, there were significant effects on sexual health knowledge (standardized mean difference [SMD] 0.72, 95% confidence interval [CI] 0.27-1.18); safer sex self-efficacy (SMD 0.17, 95% CI 0.05-0.29); safer-sex intentions (SMD 0.16, 95% CI 0.02-0.30); and sexual behaviour (OR 1.75, 95% CI 1.18-2.59). ICBIs had a greater impact on sexual health knowledge than face-to-face interventions did (SMD 0.36, 95% CI 0.13-0.58). ICBIs are effective tools for learning about sexual health, and show promising effects on self-efficacy, intention and sexual behaviour. More data are needed to analyse biological outcomes and cost-effectiveness.  相似文献   
67.
68.
The mechanisms that underlie the selection of an inhibitory GABAergic axon's postsynaptic targets and the formation of the first contacts are currently unknown. To determine whether expression of GABAA receptors (GABAARs) themselves – the essential functional postsynaptic components of GABAergic synapses – can be sufficient to initiate formation of synaptic contacts, a novel co‐culture system was devised. In this system, the presynaptic GABAergic axons originated from embryonic rat basal ganglia medium spiny neurones, whereas their most prevalent postsynaptic targets, i.e. α1/β2/γ2‐GABAARs, were expressed constitutively in a stably transfected human embryonic kidney 293 (HEK293) cell line. The first synapse‐like contacts in these co‐cultures were detected by colocalization of presynaptic and postsynaptic markers within 2 h. The number of contacts reached a plateau at 24 h. These contacts were stable, as assessed by live cell imaging; they were active, as determined by uptake of a fluorescently labelled synaptotagmin vesicle‐luminal domain‐specific antibody; and they supported spontaneous and action potential‐driven postsynaptic GABAergic currents. Ultrastructural analysis confirmed the presence of characteristics typical of active synapses. Synapse formation was not observed with control or N‐methyl‐d ‐aspartate receptor‐expressing HEK293 cells. A prominent increase in synapse formation and strength was observed when neuroligin‐2 was co‐expressed with GABAARs, suggesting a cooperative relationship between these proteins. Thus, in addition to fulfilling an essential functional role, postsynaptic GABAARs can promote the adhesion of inhibitory axons and the development of functional synapses.  相似文献   
69.
OBJECTIVE: The aim of the present cross-sectional study was to explore patient- and physician-specific determinants of physician empathy (PE) and to analyse the influence of PE on patient-reported long-term outcomes in German cancer patients. METHODS: A postal survey was administered to 710 cancer patients, who had been inpatients at the University Hospital Cologne (response rate 49.5%). PE was measured with the German translation of the consultation and relational empathy (CARE) measure, and patient-reported long-term outcomes were assessed using the major (ICD-10) depression inventory (MDI) and the EORTC quality of life (Qol) questionnaire QLQ-C30. Hypotheses were tested by structural equation modelling. RESULTS: PE had (a) a moderate indirect effect on "depression" and a smaller indirect effect on "socio-emotional-cognitive Qol" by affecting "desire for more information from the physician regarding findings and treatment options" and (b) a moderate indirect effect on "socio-emotional-cognitive Qol" and a smaller effect on "depression" via "desire for more information about health promotion". The determinant with the greatest importance was "patient-perceived general busyness of hospital staff": it had a strong negative influence on PE, indirectly influencing "desire for more information from the physician regarding findings and treatment options" and also patients' "depression". CONCLUSION: PE seems to be an important pre-requisite for information giving by physicians and through this pathway having a preventive effect on depression and improving Qol. Conversely, physicians' stress negatively influences these relationships. PRACTICE IMPLICATIONS: The research findings suggest that reducing physicians' stress at the organizational and individual may be required to enhance patient-physician communication. Empathy, as an outcome-relevant professional competence needs to be assessed and developed more intensively in medical students and physicians.  相似文献   
70.
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