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   51691篇
  免费   3516篇
  国内免费   966篇
耳鼻咽喉   398篇
儿科学   1324篇
妇产科学   1386篇
基础医学   5958篇
口腔科学   912篇
临床医学   4471篇
内科学   12326篇
皮肤病学   862篇
神经病学   4925篇
特种医学   1910篇
外国民族医学   2篇
外科学   6796篇
综合类   2082篇
现状与发展   1篇
一般理论   1篇
预防医学   2688篇
眼科学   612篇
药学   4337篇
  8篇
中国医学   962篇
肿瘤学   4212篇
  2023年   477篇
  2022年   890篇
  2021年   1933篇
  2020年   1221篇
  2019年   1377篇
  2018年   1528篇
  2017年   1258篇
  2016年   1334篇
  2015年   1654篇
  2014年   2134篇
  2013年   2626篇
  2012年   3485篇
  2011年   3515篇
  2010年   2074篇
  2009年   1854篇
  2008年   2803篇
  2007年   2794篇
  2006年   2603篇
  2005年   2407篇
  2004年   2162篇
  2003年   1876篇
  2002年   1659篇
  2001年   1443篇
  2000年   1365篇
  1999年   1268篇
  1998年   475篇
  1997年   345篇
  1996年   369篇
  1995年   281篇
  1994年   258篇
  1993年   219篇
  1992年   693篇
  1991年   575篇
  1990年   543篇
  1989年   563篇
  1988年   464篇
  1987年   429篇
  1986年   410篇
  1985年   321篇
  1984年   268篇
  1983年   219篇
  1982年   124篇
  1979年   216篇
  1978年   130篇
  1977年   112篇
  1974年   124篇
  1973年   128篇
  1972年   122篇
  1971年   111篇
  1969年   106篇
排序方式: 共有10000条查询结果,搜索用时 406 毫秒
91.
BACKGROUND: In maintenance haemodialysis patients, daily food intake is changeable; however, its relationship with nutritional status is unexplored. This study aimed to evaluate the isolated, long-term effect of daily nutrient intake on nutritional status in haemodialysis patients. METHODS: We performed a prospective 1-year controlled study in 27 chronic haemodialysis patients, without recognized risk factors for malnutrition. Each day for 1 week, four times in the year, we measured protein nitrogen appearance, and assessed dietary protein (DPI) and energy (DEI) intake from dietary diaries. We compared the nutritional outcome of patients spontaneously reducing nutrient intake below the threshold of 0.8 g/kg body weight/day for DPI and 25 kcal/kg body weight/day for DEI during the week (LOW, n = 8), with controls at adequate nutrient intake (CON, n = 19). An interventional 6-month study was then carried out in LOW to verify the cause-effect relationship. RESULTS: All patients showed a day-by-day reduction of whole nutrient intake during interdialytic period, which was mostly relevant in the third interdialytic day (L3). During the 1-year study, even in the presence of adequate dialysis dose and normal inflammatory indexes, body weight (68.0 +/- 5.5 to 65.8 +/- 5.9 kg), serum albumin (3.96 +/- 0.07 to 3.66 +/- 0.06 g/dl) and creatinine (9.2 +/- 1.1 to 8.1 +/- 0.7 mg/dl) significantly decreased in LOW but not in CON. Diaries evidenced in LOW a reduced number of meals at L3 that was explained by the fear of excessive interdialytic weight gain. During the interventional study, daily DPI and DEI increased at L3; this was associated with a significant increment of body weight, and serum albumin and creatinine levels. CONCLUSIONS: In maintenance haemodialysis patients the persistent, marked reduction of daily nutrient intake, even if limited to a single day of the week, is an independent determinant of reversible impairment of nutritional status.  相似文献   
92.
Ultrafiltration and solute transport during 60-min peritoneal dialyses of normal rabbits with intraperitoneal administration of phosphatidylcholine were compared to control values. The ultrafiltration rate of 0.27 mL/Kg/min did not increase when phosphatidylcholine was added. This agent had no effect on the ultrafiltration coefficient, sodium mass transport or solute clearances. Previously reported beneficial results with this agent could be due to repletion of a deficiency or an effect of the organic solvent. More studies of safety and efficacy of phosphatidylcholine are warranted before widespread clinical use.  相似文献   
93.
Sir, We are writing to provide some clarifications on the EditorialComment by Drüeke et al. [1]. We would have been happyto provide these very same clarifications had we been fairlyinvited to do so before the publication of the article. First of all, we would like to  相似文献   
94.
95.
96.
黄华  邸颖 《中国疗养医学》2007,16(3):130-131
目的分析对比不同时期军队疗养员消化性溃疡(PU)的患病情况。方法采用相同的病史采集和问卷调查法,以胃镜检查资料为确诊手段,对1990年和2005年两个年度的疗养员进行消化性溃疡流行病学调查。结果1990年军队疗养员消化性溃疡的患病率为158/1168人(13.53%);2005年为56/1239人(4.52%),二者相比有显著性差异P〈0.01。结论由于保健意识、生活方式和药物治疗的干预,十五年间,军队疗养员消化性溃疡的发病率显著下降。  相似文献   
97.
Global migration from several plastics (phthalate-plasticized PVC, polyurethane, polyether-polyamide copolymer and silicone rubber) into olive oil, used as a liquid simulant for fatty foods, was compared with global migration into isooctane, which has been proposed as a new fatty-food simulant. The results showed that the isooctane test (involving contact for 2 hr at 40 degrees C) is not suitable as a substitute for the olive oil test (contact for 10 days at 40 degrees C) for some types of commercial plastic materials.  相似文献   
98.
Circulating prolactin (PRL) levels, dopamine (DA) content, in vitro basal and stimulus-evoked endogenous DA release from arcuate-periventricular nuclei median-eminence fragments were studied in young (4 months) and old (24-25 months) male rats of Sprague-Dawley strain. Serum PRL levels did not differ in young and aged animals. In addition DA tissue content, basal and K+- or d-amphetamine evoked endogenous DA release did not show age-related differences. These results suggest that in male rats of the Sprague-Dawley strain the activity of tuberoinfundibular dopaminergic (TIDA) neurons does not change during senescence, unlike what happens in other strains of rats.  相似文献   
99.
100.
Right isomerism is characterized by the combination of an obstructed pulmonary outflow tract and a total anomalous pulmonary venous connection (TAPVC), which is obstructed in nearly half of the patients. Fourteen patients less than 2 years of age with right isomerism have been seen in our unit. Thirteen of them underwent palliation consisting of a systemic-pulmonary shunt (10 patients) or a combination of shunt and TAPVC repair (3). There were 7 hospital deaths (54%). The presence of obstructed pulmonary venous drainage was the major risk factor in the surgical treatment of these complex cardiac anomalies (p less than .02). Guidelines for the palliative management of right isomerism are suggested.  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