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   177705篇
  免费   16635篇
  国内免费   10876篇
耳鼻咽喉   2110篇
儿科学   2615篇
妇产科学   1574篇
基础医学   15217篇
口腔科学   3501篇
临床医学   20477篇
内科学   19461篇
皮肤病学   2566篇
神经病学   5985篇
特种医学   8024篇
外国民族医学   21篇
外科学   16918篇
综合类   39513篇
现状与发展   51篇
一般理论   7篇
预防医学   17006篇
眼科学   3644篇
药学   21047篇
  229篇
中国医学   14089篇
肿瘤学   11161篇
  2024年   674篇
  2023年   2238篇
  2022年   5709篇
  2021年   7318篇
  2020年   5886篇
  2019年   4137篇
  2018年   4490篇
  2017年   5210篇
  2016年   4552篇
  2015年   7495篇
  2014年   9546篇
  2013年   10973篇
  2012年   15956篇
  2011年   16897篇
  2010年   13325篇
  2009年   11929篇
  2008年   12821篇
  2007年   12481篇
  2006年   11393篇
  2005年   9322篇
  2004年   6717篇
  2003年   6216篇
  2002年   4883篇
  2001年   3846篇
  2000年   2931篇
  1999年   1811篇
  1998年   933篇
  1997年   792篇
  1996年   692篇
  1995年   618篇
  1994年   605篇
  1993年   396篇
  1992年   411篇
  1991年   379篇
  1990年   308篇
  1989年   272篇
  1988年   188篇
  1987年   216篇
  1986年   164篇
  1985年   112篇
  1984年   69篇
  1983年   48篇
  1982年   45篇
  1981年   27篇
  1980年   28篇
  1979年   16篇
  1965年   10篇
  1964年   10篇
  1962年   10篇
  1957年   12篇
排序方式: 共有10000条查询结果,搜索用时 11 毫秒
101.
宣肺清热颗粒剂稳定性研究   总被引:1,自引:0,他引:1  
目的:研究宣肺清热颗粒剂中橙皮甙热稳定性变化,为该颗粒剂有效期的确定、制剂生产、贮存条什提供实验参考依据。方法:采用加速实验法对橙皮甙热稳定性进行研究,用甲醇超声提取样品,HPLC进行含量测定。根据Arrhenius公式处理数据。结果:Arrhenius公式得室温下的速度常数K298=3.38×10-5/h,得出常温下该颗粒剂以橙皮甙为指标的有效期为3.6年。结论:宣肺清热颗粒剂稳定性好,初步符合中药稳定性要求。  相似文献   
102.
Familial hypercholesterolemia is a disorder of lipoprotein metabolism characterized by elevated cholesterol, low-density lipoprotein cholesterol, xanthomas and early onset atherosclerosis. Tendinitis and arthritis have been reported in patients with familial hypercholesterolemia. A report is presented of a 9-year-old girl with an acute arthritic attack who was diagnosed as homozygote familial hypercholesterolemia with hypercholesterolemic arthritis.  相似文献   
103.
The effects of vagal and sympathetic nerves on the transmembranepotentials of cardiac cells of toad were observed by means of microelectrodetechnique.The vagal nerve was stimulated there would be an increase in restingpotential and acceleration in repolarization of action potential(AP).However,ifatropine was used before stimulation the above-mentioned phenomena woulddisappear.When the sympathetic nerve was stimulated the AP amplitudeincreased,but resting potential(RP)remained the same.The increase of APresulted from the increases of overshoot.When the sympathetic nerve wasstimulated although the heart rate increased and the duration of AP wasshortened,the plateau phase of AP was prolonged.These results suggest that theeffects of vagal and sympathetic nerves on the transmembrane potential of cardiacventricular cells are coordinated and the normal characteritics of transmembranepotential are maintained by both the vagal and sympathetic nerves.  相似文献   
104.
Symmetry主动脉吻合器对大隐静脉移植物的损伤   总被引:1,自引:0,他引:1  
目的 观察使用Symmetry主动脉吻合器时对大隐静脉移植物内皮有无损伤。 方法 对 10例使用Symmetry主动脉吻合器行冠状动脉旁路移植术患者进行自身对照研究。在主动脉吻合器使用前和使用后 ,切取自体大隐静脉片断 ,进行Ⅷ因子免疫组化染色 ,对照血管内皮损伤情况。结果 血管内皮细胞均匀着色 ,为深褐色颗粒 ,损伤处褐色颗粒排列中断。吻合器组内皮损伤处平均为 2 .5 5处 ,对照组为 2 .0处。结论 Symmetry主动脉吻合器对静脉内皮细胞无明显的机械损伤  相似文献   
105.
106.
Excretion of 1,2,4-benzenetriol in the urine of workers exposed to benzene   总被引:5,自引:0,他引:5  
Urine samples were collected from 152 workers (64 men, 88 women) who had been exposed to benzene, 53 workers (men only) exposed to a mixture of benzene and toluene, and 213 non-exposed controls (113 men, 100 women). The samples were analysed for 1,2,4-benzentriol (a minor metabolite of benzene) by high performance liquid chromatography. The time weighted average solvent exposure of each worker was monitored by diffusive sampling technique. The urinary concentration of 1,2,4-benzentriol related linearly to the intensity of exposure to benzene both in men and women among workers exposed to benzene, and was suppressed by toluene co-exposure among male workers exposed to a mixture of benzene and toluene. A cross sectional balance study in men at the end of the shift of a workday showed that only 0.47% of benzene absorbed will be excreted into urine as 1,2,4-benzenetriol, in close agreement with previous results in rabbits fed benzene. The concentration of 1,2,4-benzenetriol in urine was more closely related to the concentration of quinol than that of catechol. The fact that phenol and quinol, but not catechol, are precursors of 1,2,4-benzentriol in urine was further confirmed by the intraperitoneal injection of the three phenolic compounds to rats followed by urine analysis for 1,2,4-benzenetriol.  相似文献   
107.
108.
This paper reports 50 cases of gastrointestinal tumors treated by photodynamic therapy. The dose of HpD was 5 mg/kg. Fourty-eight to 72 hours after HpD injection, laser (wavelength 630 nm, power density 100-250 J/cm2), transmitted through a quartz fiber, was given. The criteria of therapeutic effectiveness were: complete remission (CR), significant remission (SR), minor remission (MR) and no remission (NR). All patients received endoscopic examination 4 weeks after treatment. No severe complication was observed. Thirty-eight of 50 cases gave CR, SR or MR (76%). The factors effecting treatment are discussed.  相似文献   
109.
The recent discovery of a novel family of precursor processing endoproteases has greatly accelerated progress in understanding the complex mechanisms underlying the maturation of prohormones, neuropeptides, and many other precursor-derived proteins. At least six members of this family have been found thus far in mammalian species, several having alternatively spliced isoforms, and related enzymes have been identified in many invertebrates, including molluscs, insects, nematodes, and coelenterates. The proprotein convertases are all dependent on calcium for activity and all possess highly conserved subtilisin-like domains with the characteristic catalytic triad of this serine protease (ordered Asp, His, and Ser along the polypeptide chain). Two members of this family, PC2(SPC2) and PC1/PC3(SPC3), appear to play a preeminent role in neuroendocrine precursor processing. Both convertases are expressed only in the brain and in the extended neuroendocrine system, while another important family member—furin/PACE (SPC1)—is expressed more ubiquitously, in almost all tissues, and at high levels in liver. SPC2 and SPC3 exhibit acidic pH optima and other properties which enhance their activity in the acidic, calcium-enriched environment of the dense-core secretory granules of the regulated pathway in neuroendocrine cells, while furin has a neutral pH optimum and is localized predominantly to the trans Golgi network where it is retained by a C-terminal transmembrane domain. Furin processes a wide variety of precursors in the constitutive pathway, such as those of growth factors, receptors, coagulation factors, and viral glycoproteins. Recent findings on the processing of proopiomelanocortin, proinsulin, proglucagon, and several other neuroendocrine precursors by SPC2 and SPC3 are discussed, along with information on the structure, properties, evolution, developmental expression, and regulation or the convertases. An inherited defect in the fat/fat mouse which affects the processing of proinsulin, and probably also many other prohormones, due to a point mutation in carboxypeptidase E has recently been identified and has begun to provide new insights into the functional integration of the individual processing steps.  相似文献   
110.
This study made a histological comparison (light microscope and transmission electron microscope) between vascularized bone graft (VBG) and non-vascularized bone graft (NVBG) in mandible of dog.The study showed:the healing process of VBG was the same as that of bone fracture.The "creeping substitution" process of NVBG was imbued with the inflammation induced by dead bone.There was no significat difference on the bone union between VBG and NVBG perhaps for the recipient region was better vascularized.  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