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   5389篇
  免费   415篇
  国内免费   25篇
耳鼻咽喉   40篇
儿科学   259篇
妇产科学   137篇
基础医学   641篇
口腔科学   60篇
临床医学   1046篇
内科学   936篇
皮肤病学   81篇
神经病学   352篇
特种医学   180篇
外科学   508篇
综合类   173篇
一般理论   4篇
预防医学   718篇
眼科学   47篇
药学   329篇
中国医学   1篇
肿瘤学   317篇
  2023年   25篇
  2022年   39篇
  2021年   104篇
  2020年   68篇
  2019年   112篇
  2018年   115篇
  2017年   102篇
  2016年   108篇
  2015年   117篇
  2014年   152篇
  2013年   293篇
  2012年   409篇
  2011年   384篇
  2010年   234篇
  2009年   189篇
  2008年   382篇
  2007年   381篇
  2006年   382篇
  2005年   391篇
  2004年   377篇
  2003年   346篇
  2002年   357篇
  2001年   41篇
  2000年   39篇
  1999年   46篇
  1998年   68篇
  1997年   46篇
  1996年   44篇
  1995年   46篇
  1994年   32篇
  1993年   23篇
  1992年   23篇
  1991年   29篇
  1990年   23篇
  1989年   32篇
  1988年   18篇
  1987年   22篇
  1986年   11篇
  1985年   20篇
  1984年   20篇
  1983年   24篇
  1982年   16篇
  1981年   19篇
  1980年   9篇
  1979年   10篇
  1978年   11篇
  1975年   9篇
  1973年   9篇
  1972年   11篇
  1971年   9篇
排序方式: 共有5829条查询结果,搜索用时 15 毫秒
91.
The purpose of this study was to determine if there are gender differences in stress-induced pressure natriuresis and to examine the effects of adiposity on these differences. The subjects were 151 boys and 141 girls 15 to 18 years of age who underwent a 5-hour stress protocol (2-hour prestress, 1-hour stress, 2-hour poststress) after being brought into similar levels of sodium balance. The gender-by-condition interaction was significant for systolic and diastolic blood pressure (P=0.001 for both), and the effect of condition was significant for sodium excretion (P=0.001). Systolic blood pressure was higher for boys throughout the protocol (P=0.001 for each) and correlated with body mass index at each condition (range in r=0.28 to 0.35; P<0.001 for each). Hemodynamically, in boys body mass index was correlated with cardiac output during stress (r=0.23; P=0.006), which was correlated with systolic blood pressure (r=0.21; P=0.01). With respect to natriuresis, body mass index was inversely correlated with sodium excretion during stress (r=-0.22; P=0.008) and positively correlated with angiotensin II in a subsample of boys (n=89: r=0.31; P=0.003). The inverse correlation between angiotensin II and sodium excretion during stress approached significance (r=-0.17; P<0.06). Similar results were not observed for girls. In conclusion, gender differences in stress-induced pressure natriuresis appear to be related to the influence of adiposity on both blood pressure and natriuresis.  相似文献   
92.
93.

Objectives

The objective was to develop a patient decision aid (DA) to promote shared decision making (SDM) for stable, alert patients who present to the emergency department (ED) with syncope.

Methods

Using input from patients, clinicians, and experts in the field of syncope, health care design, and SDM, we created a prototype of a paper‐based DA to engage patients in the disposition decision (admission vs. discharge) after an unremarkable ED evaluation for syncope. In phase 1, we conducted one‐on‐one semistructured exploratory interviews with 10 emergency physicians and 10 ED syncope patients. In phase 2, we conducted one‐on‐one directed interviews with 15 emergency care clinicians, five cardiologists, and 12 ED syncope patients to get detailed feedback on DA content and design. We iteratively modified the aid using feedback from each interviewee until clarity and usability had been optimized.

Results

The 11 × 17‐inch, paper‐based DA, titled SynDA, includes four sections: 1) explanation of syncope, 2) explanation of future risks, 3) personalized 30‐day risk estimate, and 4) disposition options. The personalized risk estimate is calculated using a recently published syncope risk‐stratification tool. This risk estimate is stated in natural frequency and graphically displayed using a 100‐person color‐coded pictogram. Patient‐oriented questions are included to stimulate dialogue between patient and clinician. At the end of the development process, patient and physician participants expressed satisfaction with the clarity and usability of the DA.

Conclusions

We iteratively developed an evidence‐based DA to facilitate SDM for alert syncope patients after an unremarkable ED evaluation. Further testing is required to determine its effects on patient care. This DA has the potential to improve care for syncope patients and promote patient‐centered care in emergency medicine.
  相似文献   
94.

Purpose

To compare targeted imaging of vascular endothelial growth factor (VEGF) receptors vs. αvβ3 integrins in a mouse hindlimb ischemia model of peripheral artery disease.

Procedures

Male wild-type (WT) C57BL/6 mice (8- to 10-week old) (n?=?24) underwent left femoral artery ligation. The right leg served as control. Five days later, mice were injected with either VEGF receptor targeting [99mTc]DOTA-PEG-scVEGF ([99mTc]scV) (n?=?8) or with αvβ3-targeting tracer [99mTc]HYNIC-cycloRGD ([99mTc]RGD) (n?=?8) and underwent single photon emission computed tomography (SPECT) x-ray computed tomography imaging. To assess non-specific [99mTc]scV uptake, six additional mice received a mixture of [99mTc]scV and 30-fold excess of targeting protein, scVEGF. Tracer uptake as %ID was measured using volumetric regions encompassing the hindlimb muscles and as %ID/g from harvested limb muscles. Double and triple immunofluorescent analysis on tissue sections established localization of αvβ3, VEGFR-1, VEGFR-2, as well as certain cell lineage markers.

Results

Tracer uptake, as %ID/g, was higher in ligated limbs of mice injected with [99mTc]scV compared to ligated hindlimbs in mice injected with [99mTc]RGD (p?=?0.02). The ratio of tracer uptake for ligated/control hindlimb was borderline higher for [99mTc]scV than for [99mTc]RGD (p?=?0.06). Immunofluorescent analysis showed higher prevalence of VEGFR-1, VEGFR-2, and αvβ3, in damaged vs. undamaged hindlimb tissue, but with little co-localization of these markers. Double immunofluorescent staining showed partial co-localization of VEGFR-1, VEGFR-2, and αvβ3, with endothelial cell marker FVIII, but not with CD31. Immunostaining for VEGFR-1 and VEGFR-2 additionally co-localized with lineage markers for endothelial progenitor cell and monocytes/macrophages, with a more diverse pattern of co-localization for VEGFR-2.

Conclusion

In a mouse hindlimb ischemia model of peripheral artery disease, [99mTc]scV SPECT tracer-targeting VEGF receptors showed a more robust signal than [99mTc]RGD tracer-targeting αvβ3. Immunofluorescent analysis suggests that uptake of [99mTc]scV and [99mTc]RGD in damaged tissue is due to non-overlapping cell populations and reflects different dynamic processes and that enhanced uptake of [99mTc]scV may be due to the presence of VEGF receptors on additional cell types.
  相似文献   
95.
96.
97.
Abstract

This study explores the experiences of adult children as they transition their functionally and/or cognitively declining aging parents from independent living to supervised housing. A qualitative grounded theory approach was used to chronicle the experiences of adult children as their caregiving responsibilities intensified and their parents' health declined. Purposive, snowball sampling was used to enlist adult children (n = 16) who were in the process of transitioning an aging parent from an independent living situation to one providing assistance with everyday care and tasks. Semi-structured telephone interviews were conducted and designed to follow a pattern of increased frailty of the parent(s) and escalating involvement of the adult child. Two major themes emerged from the data: Changing places and everlasting love. Adult children began to intervene when cognitive or physical declines compromised the safety and well-being of the older adult and began to assume responsibility for day-to-day needs. As disabilities intensified, adult children relied on siblings, friends, social services, and health care providers to assist in planning and implementing caregiving responsibilities. Deep respect and abiding love of the aging parent(s) sustained the adult child throughout the caregiving experience.  相似文献   
98.

Context

To meet the growing need for palliative care in low-resource countries, palliative care programs should be evidence based and contextually appropriate. This study was conducted to synthesize the current evidence to guide future programmatic and research efforts.

Objectives

This systematic review evaluated palliative care outcome measures, outcomes, and interventions in low-resource countries.

Methods

After title searches, abstracts and full-text articles were screened for inclusion. Data were extracted to report on intervention models, outcome measures used, and intervention outcomes.

Results

Eighteen papers were reviewed, reporting on interventions conducted across nine low-resource countries. These interventions evaluated home-based palliative care models; a community-managed model; palliative care integrated with hospitals, hospices, or HIV clinics; and models focused on patients' self-management. Three studies were randomized controlled trials. Other studies used nonrandomized trials, cohort studies, mixed methods, pre-post test evaluation, cost-accounting evaluation, and cross-sectional surveys. Thirteen studies measured physical outcomes, 10 using multidimensional instruments. Nine studies measured psychological outcomes, eight using multidimensional instruments. Nine studies measured social outcomes, seven using multidimensional instruments. Nine studies measured outcomes across multiple domains. Across outcomes evaluated, results were reported in the direction of benefit associated with palliative care interventions.

Conclusion

Many palliative care intervention models exist to serve patients in low-resource countries. Yet, limited high-quality evidence from low-resource countries is available to document intervention outcomes. Rigorous experimental studies and greater measurement of multidimensional aspects of palliative care are needed to advance the science of palliative care in low-resource settings.  相似文献   
99.

Background

Injury is second only to cardiovascular disease in terms of acute care costs in North America. One key to improving injury care efficiency is to generate knowledge on the determinants of resource use. Socio-economic status (SES) is a documented risk factor for injury severity and mortality but its impact on length of stay (LOS) for injury admissions is unknown. This study aimed to examine the relationship between SES and LOS following injury.This multicenter retrospective cohort study was based on adults discharged alive from any trauma center (2007–2012; 57 hospitals; 65,486 patients) in a Canadian integrated provincial trauma system. SES was determined using ecological indices of material and social deprivation. Mean differences in LOS adjusted for age, gender, comorbidities, and injury severity were generated using multivariate linear regression.

Results

Mean LOS was 13.5 days. Patients in the highest quintile of material/social deprivation had a mean LOS 0.5 days (95 % CI 0.1-0.9)/1.4 days (1.1-1.8) longer than those in the lowest quintile. Patients in the highest quintiles of both social and material deprivation had a mean LOS 2.6 days (1.8-3.5) longer than those in the lowest quintiles.

Conclusions

Results suggest that patients admitted for traumatic injury who suffer from high social and/or material deprivation have longer acute care LOS in a universal-access health care system. The reasons behind observed differences need to be further explored but may indicate that discharge planning should take patient SES into consideration.
  相似文献   
100.
OBJECTIVES: This study was designed to evaluate the cost-effectiveness of screening patients with a B-type natriuretic peptide (BNP) blood test to identify those with depressed left ventricular systolic function. BACKGROUND: Asymptomatic patients with depressed ejection fraction (EF) may have less progression to heart failure if they can be identified and treated. METHODS: We used a decision model to estimate economic and health outcomes for different screening strategies using BNP and echocardiography to detect left ventricular EF <40% for men and women age 60 years. We used published data from community cohorts (gender-specific BNP test characteristics, prevalence of depressed EF) and randomized trials (benefit from treatment). RESULTS: Screening 1,000 asymptomatic patients with BNP followed by echocardiography in those with an abnormal test increased the lifetime cost of care (176,000 US dollars for men, 101,000 US dollars for women) and improved outcome (7.9 quality-adjusted life years [QALYs] for men, 1.3 QALYs for women), resulting in a cost per QALY of 22,300 US dollars for men and 77,700 US dollars for women. For populations with a prevalence of depressed EF of at least 1%, screening with BNP followed by echocardiography increased outcome at a cost < 50,000 US dollars per QALY gained. Screening would not be attractive if a diagnosis of left ventricular dysfunction led to significant decreases in quality of life or income. CONCLUSIONS: Screening populations with a 1% prevalence of reduced EF (men at age 60 years) with BNP followed by echocardiography should provide a health benefit at a cost that is comparable to or less than other accepted health interventions.  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