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   214641篇
  免费   17645篇
  国内免费   6852篇
耳鼻咽喉   1250篇
儿科学   7591篇
妇产科学   1541篇
基础医学   18934篇
口腔科学   3599篇
临床医学   22750篇
内科学   54432篇
皮肤病学   2709篇
神经病学   25708篇
特种医学   6215篇
外国民族医学   4篇
外科学   16454篇
综合类   29837篇
现状与发展   31篇
一般理论   9篇
预防医学   17055篇
眼科学   2332篇
药学   14958篇
  184篇
中国医学   9906篇
肿瘤学   3639篇
  2024年   222篇
  2023年   4330篇
  2022年   5822篇
  2021年   10880篇
  2020年   10926篇
  2019年   8304篇
  2018年   8225篇
  2017年   8166篇
  2016年   8492篇
  2015年   8205篇
  2014年   15559篇
  2013年   17010篇
  2012年   12726篇
  2011年   13761篇
  2010年   10828篇
  2009年   10414篇
  2008年   10427篇
  2007年   10087篇
  2006年   8985篇
  2005年   7413篇
  2004年   6306篇
  2003年   5420篇
  2002年   4561篇
  2001年   3939篇
  2000年   3264篇
  1999年   2716篇
  1998年   2438篇
  1997年   2088篇
  1996年   1858篇
  1995年   1926篇
  1994年   1773篇
  1993年   1512篇
  1992年   1452篇
  1991年   1277篇
  1990年   1011篇
  1989年   858篇
  1988年   804篇
  1987年   732篇
  1986年   633篇
  1985年   736篇
  1984年   617篇
  1983年   379篇
  1982年   446篇
  1981年   374篇
  1980年   282篇
  1979年   247篇
  1978年   184篇
  1977年   164篇
  1976年   135篇
  1975年   49篇
排序方式: 共有10000条查询结果,搜索用时 125 毫秒
31.
Recently, sedentary behavior recommendations have been included in the public health guidelines of multiple countries, pointing to new opportunities for prevention of chronic disease as well as a potential strategy for initiating long-term behavior change.ObjectiveTo propose an evidence-informed approach to physical activity counseling that starts with a focus on reducing sedentary time.MethodsWe put forward a case for addressing changes in sedentary behavior in clinical practice using a narrative review. We also propose a new approach for the assessment and counselling of patients with respect to movement behaviors.ResultsThere is evidence to support a stepwise approach to physical activity counseling that starts with targeting sedentary behavior, particularly in those who are highly sedentary, or those who have chronic disease, or physical impairments.ConclusionsOur approach encourages clinicians to consider sedentary behavior counseling as a critical first step to physical activity counseling. For many patients, this initial step of reducing sedentary behavior could build a pathway to an active lifestyle.Practical ImplicationsA shift from long periods of sedentary time to daily routines incorporating more light intensity physical activity could result in meaningful health improvements. Importantly, this approach may be more feasible for highly inactive patients.  相似文献   
32.
33.
34.
35.
Circadian rhythms are 24-hour natural rhythms regulated by the suprachiasmatic nucleus, also known as the "master clock". The retino-hypothalamic tract entrains suprachiasmatic nucleus with photic information to synchronise endogenous circadian rhythms with the Earth’s light-dark cycle. However, despite the robustness of circadian rhythms, an unhealthy lifestyle and chronic photic disturbances cause circadian rhythm disruption in the suprachiasmatic nucleus’s TTFL loops via affecting glutamate and γ-aminobutyric acid-mediated neurotransmission in the suprachiasmatic nucleus. Recently, considerable evidence has been shown correlating CRd with the incidence of Alzheimer's disease. The present review aims to identify the existence and signalling of endocannabinoids in CRd induced Alzheimer's disease through retino-hypothalamic tract- suprachiasmatic nucleus-cortex. Immunohistochemistry has confirmed the expression of cannabinoid receptor 1 in the suprachiasmatic nucleus to modulate the circadian phases of the master clock. Literature also suggests that cannabinoids may alter activity of suprachiasmatic nucleus by influencing the activity of their major neurotransmitter γ-aminobutyric acid or by interacting indirectly with the suprachiasmatic nucleus’s two other major inputs i.e., the geniculo-hypothalamic tract-mediated release of neuropeptide Y and serotonergic inputs from the dorsal raphe nuclei. Besides, the expression of cannabinoid receptor 2 ameliorates cognitive deficits via reduction of tauopathy and microglial activation. In conclusion, endocannabinoids may be identified as a putative target for correcting CRd and decelerating Alzheimer’s disease.  相似文献   
36.
BackgroundRecent studies have described the use of telehealth for pediatric surgical care during the COVID-19 pandemic. We aimed to evaluate equity in telehealth use by comparing rates of utilization and satisfaction with pediatric surgical telemedicine among Hispanic patients.MethodsWe conducted a retrospective cohort study of patients seen by a surgical subspecialty provider in the outpatient setting at a quaternary pediatric hospital between April 1 and June 30, 2020. Patients evaluated in the same three-month period in 2019 were analyzed as a historic control. Differences in Family Experience Survey (FES) responses based on race and ethnicity and preferred language of care were assessed using univariable and multivariable generalized linear modeling.ResultsThe pandemic cohort included fewer patients of Hispanic ethnicity and fewer Spanish-speakers. After controlling for visit type, comparison of Spanish-speaking and English-speaking patients revealed that Spanish-speaking families had significantly lower scores for FES items that evaluated healthcare provider explaining (IRR 0.74, 95% CI: 0.61–0.90), listening (IRR 0.76, 95% CI: 0.63–0.92), and time spent with the family (IRR 0.73, 95% CI: 0.60–0.89). There were no differences in FES responses based on insurance status or degree of medical complexity.ConclusionsTelehealth services were less commonly used among Hispanic and Spanish-speaking patients. Language may differentially affect family satisfaction with healthcare and telehealth solutions. Strategies to mitigate these inequities are needed and may include strengthening interpreter services and providing language-concordant care.Level of evidenceLevel IV.  相似文献   
37.
IntroductionThe risk of mortality in patients with COVID-19 was found to be significantly higher in patients who experienced thromboembolic events. Thus, several guidelines recommend using prophylactic anticoagulants in all COVID-19 hospitalized patients. However, there is uncertainty about the appropriate dosing regimen and safety of anticoagulation in critically ill patients with COVID-19. Thus, this study aims to compare the effectiveness and safety of standard versus escalated dose pharmacological venous thromboembolism (VTE) prophylaxis in critically ill patients with COVID-19.MethodsA two-center retrospective cohort study including critically ill patients aged ≥ 18-years with confirmed COVID-19 admitted to the intensive care unit (ICU) at two tertiary hospitals in Saudi Arabia from March 1st, 2020, until January 31st, 2021. Patients who received either Enoxaparin 40 mg daily or Unfractionated heparin 5000 Units three times daily were grouped under the “standard dose VTE prophylaxis and patients who received higher than the standard dose but not as treatment dose were grouped under ”escalated VTE prophylaxis dose“. The primary outcome was the occurance of thrombotic events, and the secondary outcomes were bleeding, mortality, and other ICU-related complications.ResultsA total of 758 patients were screened; 565 patients were included in the study. We matched 352 patients using propensity score matching (1:1). In patients who received escalated dose pharmacological VTE prophylaxis, any case of thrombosis and VTE were similar between the two groups (OR 1.22;95 %CI 0.52–2.86; P = 0.64 and OR 0.75; 95% CI 0.16–3.38; P = 0.70 respectively). However, the odds of minor bleeding was higher in patients who received escalated VTE prophylaxis dose (OR 3.39; 95% CI 1.08–10.61; P = 0.04). There was no difference in the 30-day mortality nor in-hospital mortality between the two groups (HR 1.17;95 %CI0.79–1.73; P = 0.43 and HR 1.08;95 %CI 0.76–1.53; P = 0.83, respectively).ConclusionEscalated-dose pharmacological VTE prophylaxis in critically ill patients with COVID-19 was not associated with thrombosis, or mortality benefits but led to an increased risk of minor bleeding. This study supports previous evidence regarding the optimal dosing VTE pharmacological prophylaxis regimen for critically ill patients with COVID-19.  相似文献   
38.
39.
40.
ObjectivesPreclinical and clinical studies indicate a role for MLC901 (NeuroAiD II) in Alzheimer's disease (AD). The primary aim was to investigate its safety as add-on therapy to standard treatment and the secondary aims its effect on cognition and slowing disease progression.DesignRandomized double-blind placebo-controlled delayed-start study.Setting and ParticipantPatients with mild to moderate probable AD by NINCDS-ADRDA criteria, stable on acetylcholinesterase inhibitors or memantine (n = 125), were randomized to receive MLC901 (early starters) or placebo (delayed starters) for 6 months, followed by a further 6 months when all patients received MLC901, in a delayed-start design (clinical trial registration: ClinicalTrials.gov, NCT03038035).MethodsThe primary outcome measure was occurrence of serious adverse events (SAEs) at 6 months. Secondary outcomes included the Alzheimer's Disease Assessment Scale–Cognitive subscale (ADAS-Cog) and other assessment scales.ResultsThere was no significant difference in the risk of SAEs between early and delayed starters at month (M) 6 (22.6% vs 27.0%, risk difference ?4.4%, 90% CI –16.9% to 8.3%). Similarly, there was no significant difference in the risk of adverse events and the occurrence of stroke or vascular events between early and delayed starters throughout the 12-month study period. Early starters did not differ significantly on ADAS-Cog from delayed starters at M6 [mean difference (MD) ?1.0, 95% CI –3.3 to 1.3] and M12 (MD –2.35, 95% CI –5.45 to 0.74) on intention-to-treat analysis. Other cognitive assessment scales did not show significant differences.Conclusions and ImplicationsThis study of 125 persons with dementia found no evidence of a significant increase in adverse events between MLC901 and placebo, thus providing support for further studies on both efficacy and safety. Analyses suggest the potential of MLC901 in slowing down AD progression, but this requires further confirmation in larger and longer studies using biomarkers for AD.  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