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   2162660篇
  免费   151588篇
  国内免费   2864篇
耳鼻咽喉   29536篇
儿科学   70383篇
妇产科学   59056篇
基础医学   314946篇
口腔科学   60380篇
临床医学   197425篇
内科学   414561篇
皮肤病学   47903篇
神经病学   169114篇
特种医学   82262篇
外国民族医学   461篇
外科学   315855篇
综合类   44646篇
现状与发展   3篇
一般理论   781篇
预防医学   167118篇
眼科学   49337篇
药学   165388篇
  12篇
中国医学   4530篇
肿瘤学   123415篇
  2018年   22623篇
  2017年   17511篇
  2016年   19502篇
  2015年   22165篇
  2014年   30643篇
  2013年   45944篇
  2012年   62690篇
  2011年   66571篇
  2010年   38976篇
  2009年   37134篇
  2008年   62581篇
  2007年   66949篇
  2006年   67218篇
  2005年   64970篇
  2004年   62332篇
  2003年   59910篇
  2002年   57920篇
  2001年   104419篇
  2000年   106839篇
  1999年   89665篇
  1998年   23944篇
  1997年   21465篇
  1996年   21657篇
  1995年   20350篇
  1994年   18845篇
  1993年   17700篇
  1992年   69536篇
  1991年   67585篇
  1990年   66036篇
  1989年   63843篇
  1988年   58459篇
  1987年   57045篇
  1986年   54199篇
  1985年   51053篇
  1984年   38057篇
  1983年   32748篇
  1982年   18784篇
  1981年   16725篇
  1979年   35318篇
  1978年   24969篇
  1977年   21554篇
  1976年   19450篇
  1975年   21437篇
  1974年   25623篇
  1973年   25011篇
  1972年   23820篇
  1971年   22298篇
  1970年   20826篇
  1969年   19869篇
  1968年   18170篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
22.
In cases of suspected violations of rules, regulations or the law by armed forces personnel, investigations are invariably mandatory. Military investigations differ from well-researched civilian criminal investigations. Differing from civilian police detectives, most military investigators – as disciplinary supervisors and military police personnel – have a number of tasks to accomplish, which include leading in combat and ensuring military readiness. Military investigations can lead to substantive negative or positive consequences for military readiness, including mental health, unit cohesion and subjective legal certainty. This impact on unit cohesion and mental health is influenced by any prior history of distress or trauma; military investigations are often preceded by contravention of internal disciplinary acts, complaints and traumatic events. This study explores factors in the differing military and legal systems of Germany and the United Kingdom (UK) that might help military personnel to successfully conduct investigations while ensuring deployment readiness and maintaining human rights.  相似文献   
23.
Objectives: To compare indicators relating to aging and health among veterans and non-veterans, and identify factors associated with subjective wellbeing (SWB) of older New Zealand veterans.

Methods: Self-reported data were obtained from participants in a longitudinal cohort study of New Zealand older adults. Responses from 352 veterans and 1500 non-veterans (age range of 55–86 and gender matched) were selected as a comparison group on indicators related to health and aging. The association of these indicators with veterans’ SWB were assessed using hierarchical regression.

Results: Apart from being older, smoking more, and having more chronic conditions, veterans did not differ from non-veterans on indicators of health and wellbeing. Mental health, physical health, purpose in life, housing satisfaction, and capabilities (choice and freedom) accounted for a significant amount of variance in veterans’ SWB.

Conclusion: Our results suggest that older veterans do not differ greatly on indices of health and aging from their non-veteran peers. Results support previous findings that lower mental and physical health is associated with lower SWB for veterans. Building upon prior findings, the current results demonstrate that interventions focusing on enhancing a sense of purpose in life, supporting one's capability to achieve, and strengthening social and physical environment through social connectedness, may serve as protective factors for SWB in veterans.  相似文献   

24.
25.
Nephrolithiasis is a common pathology encountered in the primary care and emergency department (ED) setting. In 2009 alone, there were over one million ED visits related to nephrolithiasis Higa et al. (2017) [1]. Emergent treatment options range from non-invasive pain control and patient education to lithotripsy and other invasive urologic procedures depending on stone location and related pathology. Urethral calculi are estimated to represent 0.3% of all urinary stone diseases Verit et al. (2006) [2]. There are very few case reports documenting distal urethral stone removal in the ED. Here we present a case of distal urethral stone impaction and the removal of this stone by ED providers, leading to expedited care and prevention of consultation and possible admission.  相似文献   
26.

Background and aims

There is controversy on the potentially benign nature of metabolically healthy obesity (MHO), i.e., obese persons with few or no metabolic abnormalities. So far, associations between MHO and coronary artery calcification (CAC), a measure of subclinical atherosclerosis, have mainly been studied cross-sectionally in Asian populations. We assessed cross-sectional and longitudinal MHO CAC associations in a Caucasian population.

Methods and results

In the Heinz Nixdorf Recall Study, a population-based cohort study in Germany, CAC was assessed by electron-beam tomography at baseline and at 5-year follow-up. For cross-sectional and longitudinal analyses, we included 1585 participants free of coronary heart disease at baseline, with CAC measurements at baseline and at follow-up, and with either normal weight (BMI 18.5–24.9 kg/m2) or obesity (BMI ≥30.0 kg/m2) at baseline. We used four definitions of MHO. In our main analysis, we defined obese persons as metabolically healthy if they met ≤1 of the NCEP ATP III criteria for the definition of the metabolic syndrome – waist circumference was not taken into account because of collinearity with BMI.Persons with MHO had a higher prevalence of CAC than metabolically healthy normal weight (MHNW) persons (prevalence ratio = 1.59 (95% confidence interval 1.38–1.84) for the main analysis). Persons with MHO had slightly larger odds of CAC progression than persons with MHNW (odds ratios ranged from 1.17 (0.69–1.99) to 1.48 (1.02–2.13) depending on MHO definition and statistical approach).

Conclusion

Our analyses on MHO CAC associations add to the evidence that MHO is not a purely benign health condition.  相似文献   
27.

Objective

To compare perioperative and long-term outcomes in patients undergoing hemiarch and aggressive arch replacement for acute type A aortic dissection (ATAAD).

Methods

From 1996 to 2017, we compared outcomes of hemiarch (n = 322) versus aggressive arch replacements (zones 2 and 3 arch replacement with implantation of 2-4 arch branches, n = 150) in ATAAD. Indications for aggressive arch were arch aneurysm >4 cm or intimal tear in the aortic arch that was not resectable by hemiarch replacement, or dissection of arch branches with malperfusion.

Results

Patients in the aggressive arch group were significantly younger (mean age: 57 vs 61 years old) and had significantly longer hypothermic circulatory arrest, cardiopulmonary bypass, and aortic crossclamp times. There were no significant differences in perioperative outcomes between hemiarch and aggressive arch groups, including 30-day mortality (5.3% vs 7.3%, P = .38) and postoperative stroke rate (7% vs 7%, P = .96). Over 15 years, Kaplan–Meier survival was similar between hemiarch and aggressive arch groups (log-rank P = .55, 10-year survival 70% vs 72%). Given death as a competing factor, incidence rates of reoperation over 15 years (2.1% vs 2.0% per year, P = 1) and 10-year cumulative incidence of reoperation (14% vs 12%, P = .89) for arch and distal aorta pathology were similar between the 2 groups.

Conclusions

Both hemiarch and aggressive arch replacement are appropriate approaches for select patients with ATAAD. Aggressive arch replacement should be considered for an arch aneurysm >4 cm or an intimal tear at the arch unable to be resected by hemiarch replacement, or dissection of the arch branches with malperfusion.  相似文献   
28.
29.

Background

Pulmonary hypertension (PH) is a comorbidity associated with interstitial lung disease (ILD). The purpose of this study was to evaluate the influence of PH on intrahospital mortality in lung transplantation (LT) for ILD.

Methods

We conducted a retrospective cohort study of 66 patients who underwent LT for ILD at the 12 de Octubre University Hospital (Madrid, Spain) from October 2008 to June 2014. PH was defined as mean pulmonary arterial pressure (mPAP) ≥25 mmHg on right-sided heart catheterization and intrahospital mortality as any death taken place after the transplantation of patients not being discharged.

Results

We retrospectively analyzed data of 66 patients; they were stratified by the presence or absence of PH before LT. Twenty-seven patients (41%) had PH. The PH group had a lower diffusing capacity of carbon monoxide (DLCO), carbon monoxide transfer coefficient (KCO), and 6-minute walk distance test (6MWT) and a higher total lung capacity (TLC), modified medical research council dyspnea scale (mMRC), and lung allocation score (LAS) than the non-PH group. Patients with PH more often underwent double lung transplantation (DLT; 59%) than single lung transplantation (SLT).Intrahospital mortality was 13% (9/66). No significant differences were observed in Kaplan-Meier survival curves for the PH and non-PH groups with a median survival time of 46 days versus 33 days (IQR 26–74; log-rank P = .056); however, the postoperative length of stay in the hospital was greater in the PH group.

Conclusions

In our cohort, pulmonary hypertension was not related to early mortality in lung transplantation recipients for interstitial lung diseases.  相似文献   
30.

Background and purpose

Evidence of pre-operative resting state functional magnetic resonance (RS-fMRI) validation by correlating it with clinical pre-operative status in brain tumor patients is scarce. Our aim was to validate the functional relevance of RS-fMRI by investigating the association between RS-fMRI and pre-operative motor and language function performance in patients with brain tumor.

Materials and methods

Sixty-nine patients with brain tumors were prospectively recruited. Patients with tumors near precentral gyrus (n?=?49) underwent assessment for apparent (paresis) and subtle (finger tapping) deficits. Patients with left frontal tumors in the vicinity of the inferior frontal gyrus (n?=?29) underwent assessment for gross (aphasia) and mild language (phonological verbal fluency) deficits. RS-fMRI results were extracted by spatial independent component analysis (ICA).

Results

Motor group: paretic patients showed significantly (P?=?0.01) decreased BOLD signal in ipsilesional precentral gyrus when compared to contralesional one. Significantly (P?<?0.01) lower BOLD signal was also observed in ipsilesional precentral gyrus of paretics when compared with the non-paretics. In asymptomatic patients, a strong positive correlation (r?=?0.68, P?<?0.01) between ipsilesional motor cortex BOLD signal and contralesional finger tapping performance was observed. Language group: patients with aphasia showed significantly (P?=?0.01) decreased RS-fMRI BOLD signal in left BA 44 when compared with non- aphasics. In asymptomatic patients, a strong positive correlation (r?=?0.72, P?<?0.01) between BA 44 BOLD signal and phonological fluency performance was observed.

Conclusions

Our results showed that RS-fMRI BOLD signal of motor and language networks were significantly affected by the tumors implying the usefulness of the method for assessment of the underlying functions in brain tumors patients.  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