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   24665篇
  免费   2269篇
  国内免费   2079篇
耳鼻咽喉   170篇
儿科学   249篇
妇产科学   231篇
基础医学   2925篇
口腔科学   394篇
临床医学   3305篇
内科学   3388篇
皮肤病学   165篇
神经病学   1244篇
特种医学   862篇
外国民族医学   18篇
外科学   2836篇
综合类   4361篇
现状与发展   4篇
一般理论   1篇
预防医学   1709篇
眼科学   655篇
药学   2735篇
  23篇
中国医学   1412篇
肿瘤学   2326篇
  2024年   67篇
  2023年   366篇
  2022年   625篇
  2021年   1192篇
  2020年   955篇
  2019年   825篇
  2018年   861篇
  2017年   742篇
  2016年   779篇
  2015年   1129篇
  2014年   1397篇
  2013年   1220篇
  2012年   1719篇
  2011年   1973篇
  2010年   1269篇
  2009年   1016篇
  2008年   1328篇
  2007年   1374篇
  2006年   1282篇
  2005年   1318篇
  2004年   817篇
  2003年   924篇
  2002年   689篇
  2001年   579篇
  2000年   638篇
  1999年   740篇
  1998年   457篇
  1997年   458篇
  1996年   323篇
  1995年   302篇
  1994年   306篇
  1993年   169篇
  1992年   214篇
  1991年   179篇
  1990年   150篇
  1989年   151篇
  1988年   126篇
  1987年   101篇
  1986年   75篇
  1985年   82篇
  1984年   28篇
  1983年   17篇
  1982年   13篇
  1981年   11篇
  1980年   6篇
  1979年   19篇
  1974年   1篇
  1929年   1篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
关于课堂多媒体教学的思考   总被引:10,自引:1,他引:9  
多媒体教学已成为课堂教学的一种常用手段,多媒体教学应从实际需要出发,以提高教学效果为目标;需要教师掌握多种计算机及多媒体知识技能,科学地进行教学设计;教学过程中应发挥多媒体的优势,注重师生交流。对此本文进行了探讨。  相似文献   
102.
Fluoranthene (FA) is frequently among the more abundant componentsdetected in environmental mixtures of polycyclic aromatic hydrocarbons.Several methylated fluoranthenes, although less prevalent thanFA, have also been detected as environmental pollutants. WhileFA is inactive as a tumorigenic agent on mouse skin, it doesinduce lung and liver tumors in newborn mice. Among the fiveisomers of methylfluoranthene, only 2-methylfluoranthene (2-MeFA)and 3-methylfluoranthene (3-MeFA) are active as tumor initiatorson mouse skin. A comparative bioassay was performed to determinethe relative tumorigenic activity of FA, 2-MeFA and 3-MeFA innewborn CD-1 mice. All three compounds were assayed at dosesof 3.46 and 17.3 µmol. The bioassay was terminated whenmice were 1 year old. At a dose of 17.3 µmol, FA and 2-MeFAinduced a similar incidence of lung tumors (65–96%) inboth male and female mice. However, tumor multiplicity in thelung was different between FA and 2-MeFA. At a dose of 17.3µmol, the multiplicity of lung tumors observed for miceadministered 2-MeFA ranged from 3.04 to 3.94 tumors per mouse.In contrast, animals treated with FA developed only an averageof 1.12–2.45 tumors per mouse. 3-MeFA did not induce astatistically significant incidence of lung tumors in eithermale or female mice. All three compounds when administered tonewborn mice did induce a significant incidence of liver tumorsamong male mice. The relative tumorigenic potency observed wasFA 5  相似文献   
103.
OBJECTIVE: To study how blood supply of the esophageal and gastric stumps influences the anastomotic healing after esophagogastrostomy in rabbits. METHODS: Twenty-seven New Zealand rabbits were randomly divided into 3 groups to receive esophagogastrostomy, followed by different procedures. Except for those in group I, all the rabbits were subjected to procedures of reducing the blood supply either of the esophageal or the gastric stump (group II and group III, respectively), followed by single-layer esophagogastric anastomoses using interrupted 5-0 polypropylene sutures. Ten days after operation, all the rats were killed and the anastomotic sites excised for measurement of the inner diameter, tensile strength, and hydroxyproline concentration. RESULTS: Healing of the esophagograstric anastomosis was obtained in all the rabbits but one with anastomotic leakage in group I and one with perforation of the gastric fundus in group III. The anastomotic inner diameters were similar in all the three groups, whereas the tensile strength and hydroxyproline concentration at the anastomoses decreased in group III in comparison with the other two groups (P<0.05) that had similar measurements (P>0.05). CONCLUSIONS: Extended length of the free esophageal stump does not significantly affect anastomotic healing as decrease of blood supply in the gastric stump.  相似文献   
104.
The effect of exogenous vascular endothelium growth factor (VEGF) on wound healing in an ischaemic skin flap model was evaluated in this study. Seventy-two Sprague-Dawley rats were used. Normal incisional wound and H-shaped double flaps were used as the wound models. The study was divided into two parts. In Part I, VEGF protein levels were determined from the incisional and H-shaped ischaemic wounds at 12 and 24 h, postoperatively. In Part II, tensile strength and immunohistochemical stains were examined to determine the level of microvessel density (MVD) at 1 and 2 weeks, postoperatively in simple incisional wounds, ischaemic wounds, and ischaemic wounds following 1 ml (1 microg/ml) exogenous VEGF injections into the subcutaneous tissue. The results showed a significantly higher level of VEGF protein in the ischaemic wounds than the incisional wounds. Tensile strength was statistically higher in the incisional wound group and in the ischaemic flap wounds with VEGF treatment compared to the ischaemic flaps with no treatment at 1 week, postoperatively (p>0.05). MVD data indicated that ischaemic wound repair with VEGF treatment had significantly higher MVD than the normal incisional wounds and ischaemic wounds without treatment. We conclude that exogenous application of VEGF can increase early angiogenesis and tensile strength in the ischaemic wound.  相似文献   
105.
Abstract – Dental injuries are common following facial trauma. This article presents a rare injury: the dislocation of a third molar into the maxillary sinus after complex mandibular and maxillary tuberosity fractures. The possible mechanism and clinical treatment are discussed.  相似文献   
106.
杨美华  令狐昌敏  蔡芳 《护理研究》2007,21(14):1290-1291
静脉输液治疗因其疗效快、刺激性小等优点,在抢救、治疗病人过程中发挥着非常重要的作用,故在护理工作中应用最为广泛[1]。其操作时间受多种因素影响,传统方法操作存在一次排气不成功、微量气泡残留等问题[1,2]。从2005年10月起对输液网进行了改良,并简化了输液流程,经10个月70  相似文献   
107.
本文报告不同种的金银花中微量生物元素的分布规律:不同种的金银花中微量生物元素含量的对数与其元素的原子序数成线性关系,并呈现周期性。  相似文献   
108.
In recent years, with improvement of living standard, changes in dietary structure and technical progress in medical tests, the rate of detecting fatty liver has been rising, hence constant increase in its incidence. Based on the TCM principle for differentiating syndromes, the authors have achieved remarkable curative effects in treating fatty liver. TCM Conception on Fatty Liver There is no fatty liver in the terms of TCM. However, according to its clinical manifestations, the disease may belong to the categories of “abdominal mass”, “mass at hypochondria”, “hypochondriac pain”, “accumulation of phlegm with stasis”. Its etiology and pathogenesis mainly lie in uncontrolled diet or  相似文献   
109.
目的 总结并分析上颌第一恒磨牙根管治疗的临床疗效。方法 对151颗上颌第一桓磨牙患牙进行根管治疗并观察疗效。结果 151例患牙完成根管充填136颗;治愈率为90.07%。共检出四根管32颗,检出率为21.19%。结论 熟悉髓室和根管的解剖形态,正确的根管预备,严密的根管充填,是提高上颌第一恒磨牙根管治疗疗效的必要条件。  相似文献   
110.
目的:探讨蛋白激酶C(PKC)与神经元凋亡的可能机制,方法:采用大鼠全脑缺血模型,观察脑缺血/再灌流后PKC活性,FOS表达及神经元凋亡的变化。结果:脑缺血/再灌流可以导致PKC的移位激活伴FOS表达及神经元凋亡的增加;用蛋白激酶C抑制剂灯盏花可以阻止上述变化。结论:蛋白激酶C的激活可能通过促进FOS表达参与了脑缺血/再灌流诱导的神经元凋亡。  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