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   11870篇
  免费   1113篇
  国内免费   164篇
耳鼻咽喉   17篇
儿科学   894篇
妇产科学   143篇
基础医学   2058篇
口腔科学   167篇
临床医学   625篇
内科学   1189篇
皮肤病学   179篇
神经病学   559篇
特种医学   89篇
外国民族医学   1篇
外科学   286篇
综合类   977篇
一般理论   1篇
预防医学   4101篇
眼科学   27篇
药学   1196篇
  5篇
中国医学   320篇
肿瘤学   313篇
  2023年   173篇
  2022年   195篇
  2021年   635篇
  2020年   540篇
  2019年   511篇
  2018年   469篇
  2017年   452篇
  2016年   441篇
  2015年   518篇
  2014年   730篇
  2013年   1070篇
  2012年   645篇
  2011年   752篇
  2010年   528篇
  2009年   495篇
  2008年   517篇
  2007年   531篇
  2006年   391篇
  2005年   378篇
  2004年   346篇
  2003年   323篇
  2002年   271篇
  2001年   235篇
  2000年   217篇
  1999年   187篇
  1998年   168篇
  1997年   137篇
  1996年   143篇
  1995年   126篇
  1994年   114篇
  1993年   89篇
  1992年   85篇
  1991年   59篇
  1990年   63篇
  1989年   52篇
  1988年   56篇
  1987年   43篇
  1986年   41篇
  1985年   69篇
  1984年   48篇
  1983年   47篇
  1982年   50篇
  1981年   32篇
  1980年   38篇
  1979年   27篇
  1978年   33篇
  1977年   20篇
  1976年   20篇
  1975年   11篇
  1973年   12篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
儿童食物过敏发生率逐年增加,成为一个受到社会各界关注的重要健康问题。近期研究发现维生素D从胎儿时期即可影响人体免疫系统的调节作用,母体低水平的维生素D会增加子代过敏性疾病的风险。但目前国内外关于母体维生素D营养状态与子代食物过敏相关研究较少,为此本文就母体维生素D营养状态与子代食物过敏发生相关性进行综述。  相似文献   
3.
王燕  郗轶楠  张娜  孙星  翟琪 《安徽医药》2022,26(11):2313-2317
目的观察加味补中益气汤联合戊酸雌二醇 /雌二醇环丙孕酮片治疗女性肾阴虚肝郁型更年期综合征的临床疗效及对病人血清促卵泡激素( FSH)、黄体生成激素( LH)表达的影响。方法按随机数字表法将 2019年 4月至 2021年 1月唐山市人民医院收治的 198例女性肾阴虚肝郁型更年期综合征病人分入观察组与对照组(各 99例)。对照组给予戊酸雌二醇 /雌二醇环丙孕酮片治疗,观察组在对照组治疗基础上联合加味补中益气汤治疗。比较两组病人临床疗效、中医证候评分,应用女性绝经期自测表( Kupperman改良评分)评估病人治疗前后临床症状改善情况,检测血清 FSH、LH水平及不良反应情况。结果治疗后,与对照组( 70.70%)相比,观察组总有效率( 90.90%)更高( P<0.05)。治疗后两组月经紊乱、潮热汗出、急躁易怒、阴道干涩、腰膝酸软、舌质暗红苔薄等各项中医证候评分均降低,且观察组低于对照组( P<0.05)。治疗后两组 Kupperman积分均降低,且观察组低于对照组( P<0.05);治疗后两组血清 FSH、LH水平降低,雌二醇(E2)水平升高,且观察组血清 FSH、LH水平低于对照组, E2水平高于对照组( P<0.05);与对照组( 13.13%)相比,观察组不良反应发生率( 4.04%)更低( P<0.05)。结论加味补中益气汤联合戊酸雌二醇 /雌二醇环丙孕酮片治疗女性肾阴虚肝郁型更年期综合征疗效显著,可降低中医证候评分,缓解病人病情严重程度,降低血清 FSH、LH水平,升高 E2水平,改善生殖内分泌系统功能,且不良反应少,安全可靠。  相似文献   
4.
美国心脏协会在Circulation杂志上发布了2021年促进心血管健康膳食指南。在这一最新的膳食指南中提出控制能量平衡、保持健康体质量、增加水果蔬菜的摄入、偏向选择全谷物食品、减少精加工食品的摄入、避免摄入超加工食品、合理使用植物油、尽量减少含糖食物、选择低盐饮食、合理控制饮酒等建议,对保护心血管系统具有重要的意义。本文针对这一最新的膳食指南进行解读,并结合东方饮食习惯以及近年来中国人群膳食习惯的改变,提出切合中国人群的健康膳食建议。  相似文献   
5.
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   
6.
The fractional uptake of ingested aluminium and aluminium compounds (aluminium citrate, aluminium nitrate, aluminium chloride, aluminium sulphate, aluminium hydroxide, aluminium oxide, aluminium metal, powdered aluminium pot electrolyte, acidic sodium aluminium phosphate (SALP), basic sodium aluminium phosphate (Kasal), sodium aluminium silicate and FD&C red 40 aluminium lake) from the gastro-intestinal tract of adult female rats was measured. This was determined by comparing retained body burden of 26Al at seven days post-admistration of an i.v. injection of 26Al-labelled aluminium citrate with that retained following the gastric admistration of 26Al-labelled test compounds as either solutions or suspended solid. The calculated percentage uptake of 26Al for all the aluminium solutions was similar: aluminium citrate 0.08%, aluminium chloride 0.05%, aluminium nitrate 0.05% and aluminium sulphate 0.21%. The uptake of 26Al administered as insoluble particulates was lower: 0.03% for aluminium hydroxide; 0.02% for aluminium oxide; 0.04% for powdered pot electrolyte; 0.12% for sodium aluminium silicate; and 0.09% for FD&C red 40 aluminium lake. For aluminium metal, SALP and Kasal the amount of 26Al present in the rats was insufficient to determine uptake and was less than 0.03%. The results produced for aluminium citrate, aluminium hydroxide and aluminium sulphate are close to those published for man.  相似文献   
7.
目的分析血清及组织促卵泡激素(FSH)和C3含量与卵巢囊肿(OC)大鼠病情严重程度的相关性。方法选择40只无特定病原体级雌性Wistar大鼠,按照随机数字表法分为OC模型组和对照组,每组各20只。OC模型组采用单侧卵巢一次性注射芥子油建立OC模型,对照组注射等量0.9%氯化钠溶液。分别于建模前1 d和建模后4周检测2组大鼠体重、卵巢重量以及OC大小;于建模前1 d和建模后1、2、4周采用酶联免疫吸附试验(ELISA)试剂盒检测大鼠血清及囊肿组织中FSH和补体C3含量,并进一步分析血清及组织FSH和补体C3含量与卵巢囊肿大鼠病情严重程度的相关性。结果建模前1 d,2组大鼠体重、卵巢重量以及卵巢囊肿大小差异均无统计学意义(P>0.05);建模后4周,与对照组相比,OC模型组大鼠卵巢重量和卵巢囊肿大小均显著增加(P<0.05),2组大鼠体重比较差异无统计学意义(P>0.05)。建模前1 d、建模后1周、建模后2周,2组大鼠血清及组织中FSH水平差异无统计学意义(P>0.05),建模后4周,OC模型组大鼠血清及组织中FSH水平均显著高于对照组,差异有统计学意义(P<0.05)。建模前1 d、建模后1周,2组大鼠血清及组织中补体C3水平差异无统计学意义(P>0.05),建模后2、4周,OC模型组大鼠血清及组织中补体C3水平均显著高于对照组,差异有统计学意义(P<0.05)。相关性分析结果显示,卵巢囊肿大鼠血清及组织中FSH和C3水平与其病情严重程度均呈显著正相关(P<0.05)。结论卵巢囊肿大鼠的发病与其血清及组织FSH和补体C3含量的变化密切相关,二者与该疾病病情严重程度具有显著正相关性,因此对其进展及预后评估具有重要价值。  相似文献   
8.
9.
Background/objectiveObstructive sleep apnea (OSA) is independently associated with dyslipidemia, a surrogate marker of atherosclerosis. Low-density lipoprotein (LDL)-cholesterol is accepted as a major independent risk factor for cardiovascular disease. However, non-high-density lipoprotein (HDL)-cholesterol is a better marker of atherogenic dyslipidemia and recommended as a target of lipid lowering therapy. We aimed to assess the prevalence of atherogenic dyslipidemia, and relationship between OSA severity and serum LDL-cholesterol and non-HDL cholesterol levels in OSA patients.MethodsWe retrospectively evaluated treatment naïve 2361 subjects admitted to the sleep laboratory of a university hospital for polysomnography. All subjects’ lipid profile including total cholesterol, LDL-cholesterol, HDL-cholesterol, triglycerides, and non-HDL-cholesterol were measured.ResultsOut of 2361 patients (mean age 49.6 ± 11.9 years; 68.9% male, apnea-hypopnea index 36.6 ± 28.4/h), 185 (7.8%) had no OSA and 2176 (92.2%) had OSA. Atherogenic dyslipidemia prevalence was high (57–66%) in OSA patients, and especially increased in severe OSA compared to other groups (p < 0.05). Though total and LDL-cholesterol did not differ between those with and without OSA, non-HDL-cholesterol (p = 0.020), and triglycerides (p = 0.001) were higher and HDL-cholesterol levels (p = 0.018) were lower in OSA patients than non-OSA. Non-HDL-cholesterol was significantly correlated with OSA severity (p < 0.001) and hypoxia parameters (p < 0.01), whereas LDL-cholesterol showed no correlation.ConclusionsAtherogenic dyslipidemia is highly prevalent and non-HDL-cholesterol levels are significantly increased, predominantly in severe OSA patients. Non-HDL-cholesterol but not LDL-cholesterol, is significantly correlated with OSA severity and hypoxia parameters. Therefore, it could be better to use non-HDL-cholesterol, which is a guideline recommended target of lipid therapy, as a marker of atherosclerotic cardiovascular risk in OSA patients.  相似文献   
10.
BackgroundIn 2021, the National Salt and Sugar Reduction Initiative (NSSRI) released voluntary sugar reduction targets for packaged foods and drinks in the United States.ObjectiveThe objectives of this study were to describe trends in added sugar intake from NSSRI foods and beverages among children and youth and estimate possible reductions if industry were to meet the targets.DesignThis study consisted of cross-sectional and trend analyses of demographic and 24-hour dietary recall data from eight survey cycles (2003-2004 to 2017-2018) of the National Health and Nutrition Examination Survey.Participants/settingThe study sample included 23,248 children and youth (aged 2 to 19 years).Main outcome measuresThe main outcome measure was the percent of daily calories from added sugar for foods and beverages in NSSRI categories.Statistical analyses performedFoods and beverages reported by participants were mapped to one of the NSSRI’s categories or coded as a non-NSSRI item. Trends over time in added sugar intake were assessed using regression models. To assess possible reductions in added sugar intake if industry were to meet the targets, sales-weighted mean percent reductions for 2023 and 2026 targets were applied to NSSRI items in the 2017-2018 National Health and Nutrition Examination Suvey data. Results were examined overall and by demographic characteristics.ResultsFrom 2003-2004 to 2017-2018, added sugar intake from NSSRI foods and beverages declined, but consumption remained high. During 2017-2018, NSSRI categories accounted for 70% of US child and youth added sugar intake. If industry met the NSSRI targets, US children and youth would consume 7% (2023 targets) to 21% (2026 targets) less added sugar.ConclusionsAlthough added sugar intake from NSSRI foods and drinks has declined over the past decade, added sugar intake from all sources remains high and consumption of added sugar from certain NSSRI categories has remained steady over time. If met, the NSSRI targets are expected to result in meaningful reductions in added sugar intake for US children and youth.  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