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   20514篇
  免费   1352篇
  国内免费   560篇
耳鼻咽喉   28篇
儿科学   516篇
妇产科学   338篇
基础医学   1174篇
口腔科学   144篇
临床医学   2127篇
内科学   6483篇
皮肤病学   73篇
神经病学   1058篇
特种医学   367篇
外科学   887篇
综合类   3328篇
现状与发展   2篇
预防医学   1956篇
眼科学   213篇
药学   2463篇
  16篇
中国医学   1006篇
肿瘤学   247篇
  2024年   66篇
  2023年   324篇
  2022年   666篇
  2021年   980篇
  2020年   704篇
  2019年   590篇
  2018年   559篇
  2017年   586篇
  2016年   687篇
  2015年   742篇
  2014年   1345篇
  2013年   1471篇
  2012年   1346篇
  2011年   1397篇
  2010年   1140篇
  2009年   1033篇
  2008年   1028篇
  2007年   870篇
  2006年   752篇
  2005年   680篇
  2004年   557篇
  2003年   463篇
  2002年   355篇
  2001年   376篇
  2000年   285篇
  1999年   241篇
  1998年   204篇
  1997年   202篇
  1996年   177篇
  1995年   174篇
  1994年   175篇
  1993年   145篇
  1992年   131篇
  1991年   133篇
  1990年   134篇
  1989年   119篇
  1988年   125篇
  1987年   108篇
  1986年   105篇
  1985年   148篇
  1984年   136篇
  1983年   78篇
  1982年   112篇
  1981年   89篇
  1980年   111篇
  1979年   79篇
  1978年   71篇
  1977年   74篇
  1976年   61篇
  1973年   59篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
101.
102.
103.
Abstract

For seven weeks, 37 overweight adults followed a hypocaloric diet based on Orthodox Fasting (OF). A hypocaloric, time restricted eating (TRE) plan (eating between 08:00 to 16:00?h, water fasting from 16:00 to 08:00?h) was followed by 23 Body Mass Index (BMI)-matched participants. Anthropometric, glycaemic and inflammation markers and serum lipids were assessed before and after the diets. Both OF and TRE groups demonstrated reductions in BMI (28.54?±?5.45 vs 27.20?±?5.10?kg/m2, p?<?0.001 and 26.40?±?4.11 vs 25.81?±?3.78?kg/m2 p?=?0.001, respectively). Following the intervention, the OF group presented lower concentrations of total and low-density lipoprotein-cholesterol, compared with the pre-fasting values (178.40?±?34.14 vs 197.17?±?34.30?mg/dl, p?<?0.001 and 105.89?±?28.08 vs 122.37?±?29.70?mg/dl, p?<?0.001, respectively). Neither group manifested significant differences in glycaemic and inflammatory parameters. Our findings suggest that OF has superior lipid lowering effects than the TRE pattern.  相似文献   
104.
摘 要:目的:探讨通过调节体质预防老年人常见病的对策。 方法:选择天津市某社区参加免费健康体检的65岁以上 老年人,对其进行中医体质辨识,并收集相关临床检测指标,对所有数据进行统计学分析。结果:女性腹型肥胖发生率为 86.4%,明显高于男性的54.3%。参加体检的老年人中偏颇体质占58.9%。不同性别的老年人疾病患病率只在血脂异常方面存 在明显差异。腹型肥胖老年人的血脂异常患病率明显高于正常体型老年人。腹型肥胖老年人气虚质比例明显高于正常体型老 年人, 而正常体型老年人中平和质的比例明显高于腹型肥胖老年人。结论:老年女性及老年腹型肥胖者是血脂异常预防的 重点人群。可针对性开展对老年女性及腹型肥胖老年人的中医体质调摄。  相似文献   
105.
Trypanosoma cruzi (epimastigotes), Crithidia fasciculata and Leishmania mexicana (promastigotes) were grown in a brain-heart-tryptose medium supplemented with heat-inactivated fetal calf serum. T. cruzi and C. fasciculata utilized glucose completely during the log phase of growth, whereas L. mexicana used significant amounts of the carbohydrate only at the end of the log phase and at the beginning of the stationary phase. In all cases glucose consumption resulted in excretion of succinate, and much smaller amounts of acetate. C. fasciculata and L. mexicana produced very small amounts of pyruvate. C. fasciculata produced ethanol, which was taken up again and metabolysed after glucose was exhausted. Lactate and malate were not produced. The cells were disrupted by sonic disintegration, and the activities of some key enzymes of carbohydrate and amino acid catabolism were assayed in the whole homogenates. Phosphoenolpyruvate carboxykinase was present in the three organisms; L. mexicana presented the highest specific activity. The activity of this enzyme was maximal during glucose consumption, and slightly decreased after glucose was exhausted. This suggests that the role played by the enzyme is glycolytic and not gluconeogenic; the latter is the case in most higher organisms. Hexokinase and pyruvate kinase presented their highest levels in C. fasciculata and T. cruzi during glucose consumption. L. mexicana, which was in active glycolysis during the whole experimental period, presented the highest specific activities of both enzymes. Citrate synthase, on the other hand, increased in C. fasciculata and, to a lesser extent, in T. cruzi, after glucose was exhausted; the enzyme could not be detected in L. mexicana. The NAD-linked glutamate dehydrogenase increased considerably in C. fasciculata and T. cruzi after glucose was exhausted, suggesting a catabolic role for the enzyme. This increase coincided with an increase in NH3 production by both organisms after glucose consumption. The NADP-linked glutamate dehydrogenase, on the other hand, presented a maximum about the time when glucose was exhausted, and then decreased again, which suggests a catabolic role for the enzyme. Both glutamate dehydrogenases had low activities in L. mexicana; this fits in well with the low NH3 production throughout the culture of this organism. The results are in good agreement with current ideas on the mechanism of aerobic glucose fermentation by trypanosomatids, and suggest that, under the experimental conditions used, both T. cruzi and C. fasciculata used glucose perferentially over amino acids for growth.  相似文献   
106.
BACKGROUNDS: Hemangiomas are highly prevalent in newborns and infants and can lead to severe complications. However, the pathogenesis of hemangiomas is still unknown. This study was designed to examine the potential of human monocytes to differentiate into hemangioma endothelial cells. METHODS: Purified monocytes from adult human peripheral blood were cultured under a conditional culture environment supplemented with basic fibroblast growth factor and vascular endothelial growth factor. Cells cultured for 2 weeks were subjected to histological and immunochemical examinations in order to determine the expression of specific markers for hemangioma endothelial cells. RESULTS: Monocytes cultured for 2 weeks in angiogenic medium expressed human erythrocyte-type glucose transporter protein, FcgammaRII, and several other endothelial markers, all of which are deemed specific markers for hemangioma endothelial cells. However, neither CD133 nor alpha smooth muscle actin was detected in our monocyte culture. CONCLUSION: Our data suggested that monocytes are capable of differentiating into hemangioma endothelial cells under the angiogenic stimulation from microenvironment of proliferative hemangioma.  相似文献   
107.
低血流心肌缺血诱导GLUT4基因表达   总被引:1,自引:0,他引:1  
目的:探讨低血流心肌缺血促进葡萄糖摄取增加的机制。方法:采用Northrn印迹法观察缺血心肌葡萄转运子4(GLUT4)mRNA的表达,并利用蛋白质印迹法分析心肌GLUT4多肽的表达,结果:局部心肌低血流缺血后,心肌GLUT4mRNA和GLUT4多肽表达明显增加;同时伴随缺血心肌葡萄糖摄取明显增多。结论:心肌缺血能刺激GLUT4 mRNA和GLUT4多肽表达,使GLUT4数增加,进而促进心肌葡萄糖摄取增多,使缺血心肌能量需求得以平衡,有助于缺血心肌功能的恢复,提示低血流缺 刺激心肌GLUT4表达是一个重要的代偿性保护机制。  相似文献   
108.
目的:观察大鼠心脏两种负荷状况时环化鸟苷一磷酸(cGMP)对心肌细胞摄取葡萄糖的影响。方法:应用cGMP类似物8-BrcGMP、一氧化氮合酶(NOS)抑制剂L-NAME和NO供体SNAP灌注Wistar大鼠心脏,并用放免法测定组织内cGMP浓度。根据2-^3H标记率计算葡萄糖摄取量。结果:低负荷状况时8-BrcGMP使冠脉血流增加,细胞内糖原浓度升高。高负荷状况时8-BrcGMP使心排出量减少,心肌细胞对葡萄糖摄取减少和使糖原浓度降低。L-NAME降低心肌细胞cGMP逍度,并刺激葡萄糖摄取,而SNAP作用则相反。结论:心肌细胞内cGMP浓度升高,可抑制葡萄糖摄取;而NOS抑制剂L-NAME则能降低cGMP浓度,使心肌细胞葡萄糖摄取增加,糖原分解减少,使缺血心肌功能受到保护。  相似文献   
109.
胰岛素与低血流缺血刺激犬心肌GLUT4基因表达呈相加作用   总被引:1,自引:1,他引:0  
目的:观察胰岛素与低血糖缺血刺激心肌葡萄糖转运子4(GLUT4)基因是否呈相加作用。方法:采用North-ernblot法分析心肌GLUT4mRNA,采用免疫印迹法分析心肌GLUT4基因表达。结果:输注胰岛素使局部低血流心肌GLUT4mRNA和GLUT4基因表达增加2.3-2.5倍,同时伴随心肌葡萄糖摄取明显增多达4倍.结论:胰岛素与低血流缺血刺激心肌致GLUT4mRNA和GLUT4表达呈相加作用,其结果使GLUT4数量明显增加,进而使心肌葡萄糖摄取量增加,此机制在缺血心肌能量代谢过程中起着重要的代谢性调节作用。  相似文献   
110.
[目的 ]研究大豆胚轴甲醇提取物对糖尿病大鼠血糖、血脂及过氧化脂质代谢的影响 .[方法 ]甲醇提取大豆胚轴中的异黄酮类和皂甙 ,以薄层色谱法、高效液相色谱法检测其组成 .给GK/Jcl糖尿病大鼠长期食用添加 10 0 g/kg大豆胚轴甲醇提取物的饲料 ,观察和测定相应生物化学指标 .[结果 ]长期食用大豆胚轴甲醇提取物的糖尿病大鼠的血糖水平下降 ,血清过氧化脂质降低 ,高密度脂蛋白胆固醇增高 ,血清总胆固醇和甘油三脂却无明显变化 .[结论 ]大豆胚轴甲醇提取物具有显著的降低血糖、改善糖耐量、降低脂质过氧化和升高高密度脂蛋白胆固醇的作用  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