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   12868篇
  免费   1135篇
  国内免费   180篇
耳鼻咽喉   21篇
儿科学   842篇
妇产科学   39篇
基础医学   1801篇
口腔科学   191篇
临床医学   574篇
内科学   937篇
皮肤病学   152篇
神经病学   391篇
特种医学   146篇
外科学   193篇
综合类   1029篇
一般理论   1篇
预防医学   4901篇
眼科学   25篇
药学   1791篇
  6篇
中国医学   877篇
肿瘤学   266篇
  2024年   37篇
  2023年   210篇
  2022年   680篇
  2021年   1046篇
  2020年   584篇
  2019年   549篇
  2018年   509篇
  2017年   464篇
  2016年   476篇
  2015年   531篇
  2014年   758篇
  2013年   1097篇
  2012年   673篇
  2011年   770篇
  2010年   573篇
  2009年   525篇
  2008年   553篇
  2007年   552篇
  2006年   364篇
  2005年   400篇
  2004年   346篇
  2003年   309篇
  2002年   235篇
  2001年   226篇
  2000年   167篇
  1999年   158篇
  1998年   167篇
  1997年   116篇
  1996年   127篇
  1995年   115篇
  1994年   110篇
  1993年   76篇
  1992年   81篇
  1991年   48篇
  1990年   57篇
  1989年   48篇
  1988年   58篇
  1987年   36篇
  1986年   36篇
  1985年   49篇
  1984年   38篇
  1983年   33篇
  1982年   39篇
  1981年   30篇
  1980年   22篇
  1979年   21篇
  1978年   27篇
  1977年   13篇
  1976年   16篇
  1975年   9篇
排序方式: 共有10000条查询结果,搜索用时 93 毫秒
1.
BackgroundVoices for Food was a longitudinal community, food pantry–based intervention informed by the social ecological model, and designed to improve food security, dietary intake, and quality among clients, which was carried out in 24 rural food pantries across 6 Midwestern states.ObjectiveOur objective was to evaluate changes in adult food security, dietary intake, and quality from baseline (2014) to follow-up (2016), and to assess the role of adult food security on dietary outcomes.DesignA multistate, longitudinal, quasi-experimental intervention with matched treatment and comparison design was used to evaluate treatment vs comparison group changes over time and changes in both groups over time.Participants/settingAdult food pantry clients (n = 617) completed a demographic food security survey, and up to three 24-hour dietary recalls at baseline (n = 590) and follow-up (n = 160).InterventionCommunity coaching served as the experimental component, which only “treatment” communities received, and a food council guide and food pantry toolkit were provided to both “treatment” and matched “comparison” communities.Main outcome measuresChange in adult food security status, mean usual intakes of nutrients and food groups, and Healthy Eating Index-2010 scores were the main outcome measures.Statistical analyses performedLinear mixed models estimated changes in outcomes by intervention group and by adult food security status over time.ResultsImprovements in adult food security score (–0.7 ± 0.3; P = .01), Healthy Eating Index-2010 total score (4.2 ± 1.1; P < .0001), and empty calories component score (3.4 ± 0.5; P <.0001) from baseline to follow-up were observed in treatment and comparison groups, but no statistically significant changes were found for adult food security status, dietary quality, and usual intakes of nutrients and food groups between the 2 groups over time. The intervention effect on dietary quality and usual intake changes over time by adult food security status were also not observed.ConclusionsFood pantry clients in treatment and comparison groups had higher food security and dietary quality at the follow-up evaluation of the Voices for Food intervention trial compared with baseline, despite the lack of difference among the groups as a result of the experimental coaching component.  相似文献   
2.
In forensic medicine, although various alcohols have been reported as indicators of decomposition in collected blood, no studies have examined short-chain fatty acids as indicators. In this study, the blood n-butyric acid concentration was quantified, and the association between n-butyric acid and decomposition was investigated to determine whether the detection of n-butyric acid could be a new indicator of decomposition. Among the forensic autopsies performed from 2016 to 2018 in our laboratory, the cases were divided into decomposed (n = 20) and non-decomposed (n = 20) groups based on macroscopic findings. Blood samples collected at the time of autopsy were derivatized with 3-nitrophenylhydrazine hydrochloride after solid-phase extraction. The n-butyric acid concentration was measured using liquid chromatography–tandem mass spectrometry. In addition, ethanol and n-propanol were measured using a gas chromatography-flame ionization detector. There was a significant difference (p < 0.01) in the concentrations of n-butyric acid between the decomposed and non-decomposed groups (0.343 ± 0.259 [0.030–0.973] and 0.003 ± 0.002 [0.001–0.007] mg/mL, respectively). In the decomposed group, n-butyric acid was detected at high concentrations, even in cases where n-propanol was low. These results suggest that n-butyric acid is more likely to be an indicator of blood decomposition than n-propanol.  相似文献   
3.
4.
5.
6.
7.
8.
9.
Pancreatic ductal adenocarcinoma (PDAC) is predicted to become the second leading cause of cancer-related mortality within the next decade, with limited effective treatment options and a dismal long-term prognosis for patients. Genomic profiling has not yet manifested clinical benefits for diagnosis, treatment or prognosis in PDAC, due to the lack of available tissues for sequencing and the confounding effects of low tumour cellularity in many biopsy specimens. Increasing focus is now turning to the use of minimally invasive liquid biopsies to enhance the characterisation of actionable PDAC tumour genomes. Circulating tumour DNA (ctDNA) is the most comprehensively studied liquid biopsy analyte in blood and can provide insight into the molecular profile and biological characteristics of individual PDAC tumours, in real-time and in advance of traditional imaging modalities. This can pave the way for identification of new therapeutic targets, novel risk variants and markers of tumour response, to supplement diagnostic screening and provide enhanced scrutiny in treatment stratification. In the roadmap towards the application of precision medicine for clinical management in PDAC, ctDNA analyses may serve a leading role in streamlining candidate biomarkers for clinical integration. In this review, we highlight recent developments in the use of ctDNA-based liquid biopsies for PDAC and provide new insights into the technical, analytical and biological challenges that must be overcome for this potential to be realised.  相似文献   
10.
BackgroundChildren with IgE-mediated cow's milk allergy (IgE-CMA) with gastrointestinal symptoms tolerate yogurt at 100%. Yogurt tolerance in children with IgE-CMA with urticaria and anaphylaxis was 7%.MethodsWe enrolled children with IgE-CMA with cutaneous, respiratory, gastrointestinal and anaphylactic symptoms. All performed prick by prick (PbP) and oral food challenge (OFC) with yogurt. Some children performed also an OFC with CM mixed with wheat flour and baked, baked liquid CM, parmesan.Results34 children were enrolled, 31/34 (91%) with systemic adverse reaction after ingestion of CM (systemic CMA), 3/34 (9%) with isolated contact urticaria (ICU CMA). PbP with yogurt was negative only in one patient. OFC with yogurt was passed (that is, the OFC was negative) by 20/31 (64%) of the children with systemic CMA. 10/11 (91%) of the patients who failed OFC (that is, the OFC was positive) with yogurt were positive to SPT with casein vs. 8/20 (40%) of the patients who passed it (p = 0.018). None of the 19 children who passed OFC with yogurt failed all OFC with processed CM forms other than yogurt that tested vs. 4/8 among those who failed OFC with yogurt (p = 0.006). The rub test with yogurt was negative in 1/3 (33%) of the patients with ICU CMA.ConclusionsThe results of our study are placed alongside others already present in the literature and concerning other methods of processing CM proteins and help to reduce the dietary restrictions of the majority of children with systemic IgE-CMA.  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