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   10273篇
  免费   815篇
  国内免费   150篇
耳鼻咽喉   67篇
儿科学   449篇
妇产科学   309篇
基础医学   1446篇
口腔科学   204篇
临床医学   1023篇
内科学   2404篇
皮肤病学   149篇
神经病学   695篇
特种医学   358篇
外科学   1382篇
综合类   192篇
一般理论   10篇
预防医学   638篇
眼科学   274篇
药学   696篇
中国医学   98篇
肿瘤学   844篇
  2023年   54篇
  2022年   41篇
  2021年   181篇
  2020年   130篇
  2019年   233篇
  2018年   254篇
  2017年   191篇
  2016年   198篇
  2015年   250篇
  2014年   311篇
  2013年   407篇
  2012年   657篇
  2011年   666篇
  2010年   379篇
  2009年   356篇
  2008年   624篇
  2007年   638篇
  2006年   626篇
  2005年   581篇
  2004年   524篇
  2003年   449篇
  2002年   409篇
  2001年   397篇
  2000年   393篇
  1999年   317篇
  1998年   123篇
  1997年   88篇
  1996年   92篇
  1995年   78篇
  1994年   59篇
  1993年   75篇
  1992年   180篇
  1991年   156篇
  1990年   144篇
  1989年   148篇
  1988年   133篇
  1987年   122篇
  1986年   114篇
  1985年   96篇
  1984年   65篇
  1983年   47篇
  1982年   40篇
  1981年   30篇
  1980年   25篇
  1979年   34篇
  1978年   17篇
  1977年   20篇
  1976年   14篇
  1974年   14篇
  1972年   11篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
Purpose

To examine cross-sectional associations between food insecurity and 12-month eating disorders, mood disorders, and anxiety disorders among U.S. adults.

Methods

This study used data collected between 2001 and 2003 from 2914 participants in the National Comorbidity Survey-Replication, a nationally representative sample of U.S. adults (mean age = 44.9 years; 53.4% female). Twelve-month food insecurity was assessed with a modified version of the Short Form U.S. Household Food Security Scale. Twelve-month DSM-IV diagnoses of mental disorders were based on the World Health Organization Composite International Diagnostic Interview. Modified Poisson regression models were conducted, adjusting for age, sex, race/ethnicity, education, and income-to-poverty ratio.

Results

Food insecurity was experienced by 11.1% of participants. Food insecurity was associated with greater prevalence of bulimic-spectrum eating disorders (prevalence ratio [PR] = 3.81; 95% confidence interval [CI] 2.26–6.42), mood disorders (PR = 2.53; 95% CI 1.96–3.29), and anxiety disorders (PR = 1.69; 95% CI 1.39–2.07).

Conclusion

Results indicate that food insecurity is associated with a range of internalizing mental disorders, though these findings should be confirmed with contemporary data to reflect DSM-5 diagnostic updates and the economic effects of the COVID-19 pandemic. Findings from this study emphasize the need to expand food insecurity interventions and improve access to mental health services for food-insecure populations.

  相似文献   
2.
IntroductionThe coronavirus disease 2019 (COVID-19) pandemic was expected to have a negative impact on organ donation. With the differences in health care systems and lockdown policies in various regions, the pandemic's effect on organ donation and transplant service may vary. Most of the deceased donor organ referrals in our hospital came from non–intensive care units (ICUs). The objective of this study is to report our experience and quantify the effects of the COVID-19 pandemic on deceased donor organ donation in our center.MethodsThis was a retrospective observational study comparing the deceased donor organ donation activity during the period January 23 to November 30, 2020 with the same period in 2018 in Queen Elizabeth Hospital, Hong Kong.ResultsThere was a 26.9% reduction in deceased donor organ donor referral in 2020 compared with 2018. No significant difference in the proportion of referrals from ICU or non-ICU areas between the 2 time periods was observed. The brain death confirmation rate was significantly higher in 2020 (40.8% vs 20.2%, P = .003). Nine patients had family consent for organ donation in 2020 (vs 7 patients in the same period in 2018). There were no significant differences in consent rate and number of recovered organs between the 2 periods.ConclusionsWith effective measures to limit the spread of COVID-19 in a community, it is possible to support the needs of both patients with COVID-19 and deceased donor organ donation services.  相似文献   
3.
4.
BACKGROUND Nonalcoholic fatty liver disease(NAFLD)and type-2 diabetes mellitus(T2DM)have an intricate bidirectional relationship.Individuals with T2DM,not only have a higher prevalence of non-alcoholic steatosis,but also carry a higher risk of progression to nonalcoholic steatohepatitis.Experts still differ in their recommendations of screening for NAFLD among patients with T2DM.AIM To study the prevalence of NAFLD and advanced fibrosis among our patient population with T2DM.METHODS During the study period(November 2018 to January 2020),59 adult patients with T2DM and 26 non-diabetic control group individuals were recruited prospectively.Patients with known significant liver disease and alcohol use were excluded.Demographic data and lab parameters were recorded.Liver elastography was performed in all patients.RESULTS In the study group comprised of patients with T2DM and normal alanine aminotransferase levels(mean 17.8±7 U/L),81%had hepatic steatosis as diagnosed by elastography.Advanced hepatic fibrosis(stage F3 or F4)was present in 12%of patients with T2DM as compared to none in the control group.Patients with T2DM also had higher number of individuals with grade 3 steatosis[45.8%vs 11.5%,(P<0.00001)and metabolic syndrome(84.7%vs 11.5%,P<0.00001)].CONCLUSION A significant number of patients with T2DM,despite having normal transaminase levels,have NAFLD,grade 3 steatosis and advanced hepatic fibrosis as measured by liver elastography.  相似文献   
5.
BackgroundThe COVID-19 pandemic has strained the healthcare systems across the world but its impact on acute stroke care is just being elucidated. We hypothesized a major global impact of COVID-19 not only on stroke volumes but also on various aspects of thrombectomy systems.AimsWe conducted a convenience electronic survey with a 21-item questionnaire aimed to identify the changes in stroke admission volumes and thrombectomy treatment practices seen during a specified time period of the COVID-19 pandemic.MethodsThe survey was designed using Qualtrics software and sent to stroke and neuro-interventional physicians around the world who are part of the Global Executive Committee (GEC) of Mission Thrombectomy 2020, a global coalition under the aegis of Society of Vascular and Interventional Neurology, between April 5th and May 15th, 2020.ResultsThere were 113 responses to the survey across 25 countries with a response rate of 31% among the GEC members. Globally there was a median 33% decrease in stroke admissions and a 25% decrease in mechanical thrombectomy (MT) procedures during the COVID-19 pandemic period until May 15th, 2020 compared to pre-pandemic months. The intubation policy for MT procedures during the pandemic was highly variable across participating centers: 44% preferred intubating all patients, including 25% of centers that changed their policy to preferred-intubation (PI) from preferred non-intubation (PNI). On the other hand, 56% centers preferred not intubating patients undergoing MT, which included 27% centers that changed their policy from PI to PNI. There was no significant difference in rate of COVID-19 infection between PI versus PNI centers (p=0.60) or if intubation policy was changed in either direction (p=1.00). Low-volume (<10 stroke/month) compared with high-volume stroke centers (>20 strokes/month) were less likely to have neurointerventional suite specific written personal protective equipment protocols (74% vs 88%) and if present, these centers were more likely to report them to be inadequate (58% vs 92%).ConclusionOur data provides a comprehensive snapshot of the impact on acute stroke care observed worldwide during the pandemic. Overall, respondents reported decreased stroke admissions as well as decreased cases of MT with no clear preponderance in intubation policy during MT.Data access statementThe corresponding author will consider requests for sharing survey data. The study was exempt from institutional review board approval as it did not involve patient level data.  相似文献   
6.
7.
8.
The World Health Organization (WHO) recently produced guidelines advising a treat‐all policy for HCV to encourage widespread treatment scale‐up for achieving HCV elimination. We modelled the prevention impact achieved (HCV infections averted [IA]) from initiating this policy compared with treating different subgroups at country, regional and global levels. We assessed what country‐level factors affect impact. A dynamic, deterministic HCV transmission model was calibrated to data from global systematic reviews and UN data sets to simulate country‐level HCV epidemics with ongoing levels of treatment. For each country, the model projected the prevention impact (in HCV IA per treatment undertaken) of initiating four treatment strategies; either selected randomly (treat‐all) or targeted among people who inject drugs (PWID), people aged ≥35, or those with cirrhosis. The IA was assessed over 20 years. Linear regression was used to identify associations between IA per treatment and demographic factors. Eighty‐eight countries (85% of the global population) were modelled. Globally, the model estimated 0.35 (95% credibility interval [95%CrI]: 0.16‐0.61) IA over 20 years for every randomly allocated treatment, 0.30 (95%CrI: 0.12‐0.53) from treating those aged ≥35 and 0.28 (95%CrI: 0.12‐0.49) for those with cirrhosis. Globally, treating PWID achieved 1.27 (95%CrI: 0.68‐2.04) IA per treatment. The IA per randomly allocated treatment was positively associated with a country's population growth rate and negatively associated with higher HCV prevalence among PWID. In conclusion, appreciable prevention benefits could be achieved from WHO’s treat‐all strategy, although greater benefits per treatment can be achieved through targeting PWID. Higher impact will be achieved in countries with high population growth.  相似文献   
9.
A pathological feature in atherosclerosis is the dysfunction and death of vascular endothelial cells (EC). Oxidized low‐density lipoprotein (LDL), known to accumulate in the atherosclerotic arterial walls, impairs endothelium‐dependent relaxation and causes EC apoptosis. A major bioactive ingredient of the oxidized LDL is lysophosphatidylcholine (LPC), which at higher concentrations causes apoptosis and necrosis in various EC. There is hitherto no report on LPC‐induced cytotoxicity in brain EC. In this work, we found that LPC caused cytosolic Ca2+ overload, mitochondrial membrane potential decrease, p38 activation, caspase 3 activation and eventually apoptotic death in mouse cerebral bEND.3 EC. In contrast to reported reactive oxygen species (ROS) generation by LPC in other EC, LPC did not trigger ROS formation in bEND.3 cells. Pharmacological inhibition of p38 alleviated LPC‐inflicted cell death. We examined whether heparin could be cytoprotective: although it could not suppress LPC‐triggered Ca2+ signal, p38 activation and mitochondrial membrane potential drop, it did suppress LPC‐induced caspase 3 activation and alleviate LPC‐inflicted cytotoxicity. Our data suggest LPC apoptotic death mechanisms in bEND.3 might involve mitochondrial membrane potential decrease and p38 activation. Heparin is protective against LPC cytotoxicity and might intervene steps between mitochondrial membrane potential drop/p38 activation and caspase 3 activation.  相似文献   
10.
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