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   9543篇
  免费   899篇
  国内免费   456篇
耳鼻咽喉   84篇
儿科学   178篇
妇产科学   123篇
基础医学   1220篇
口腔科学   127篇
临床医学   1220篇
内科学   1740篇
皮肤病学   123篇
神经病学   500篇
特种医学   567篇
外国民族医学   1篇
外科学   811篇
综合类   1004篇
现状与发展   4篇
一般理论   1篇
预防医学   582篇
眼科学   421篇
药学   1047篇
  6篇
中国医学   384篇
肿瘤学   755篇
  2024年   26篇
  2023年   138篇
  2022年   316篇
  2021年   390篇
  2020年   311篇
  2019年   269篇
  2018年   269篇
  2017年   243篇
  2016年   228篇
  2015年   401篇
  2014年   416篇
  2013年   460篇
  2012年   603篇
  2011年   623篇
  2010年   431篇
  2009年   303篇
  2008年   440篇
  2007年   412篇
  2006年   414篇
  2005年   402篇
  2004年   312篇
  2003年   279篇
  2002年   266篇
  2001年   250篇
  2000年   229篇
  1999年   250篇
  1998年   165篇
  1997年   184篇
  1996年   200篇
  1995年   167篇
  1994年   118篇
  1993年   112篇
  1992年   132篇
  1991年   118篇
  1990年   109篇
  1989年   141篇
  1988年   106篇
  1987年   101篇
  1986年   96篇
  1985年   83篇
  1984年   47篇
  1983年   42篇
  1982年   30篇
  1981年   38篇
  1980年   36篇
  1979年   38篇
  1978年   34篇
  1977年   24篇
  1976年   18篇
  1975年   24篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
91.
采用密度梯度离心技术对40例孕妇外用血中胎儿细胞进行富集,并用PCR技术扩增了Y染色体特异重复序列,以产前基因诊断胎儿性别,结果38例胎儿性别诊断准确,证明此技术可作为无创伤性方法用于X连锁遗传病的产前诊断.  相似文献   
92.
The aims of this study were to assess the role played by alveolar macrophages, tumor necrosis factor alpha (TNF-alpha), and interleukin-1 alpha (IL-1 alpha) in pulmonary immunity against Pseudomonas aeruginosa in animals that have been immunized via the gut-associated lymphoid tissue. Following intra-Peyer's patch immunization and subsequent intratracheal challenge with live bacteria, significantly enhanced bacterial clearance from the lungs correlated with an increase in bronchoalveolar neutrophils, increased recruitment and phagocytic activity of alveolar macrophages, and accelerated production of TNF-alpha in the bronchoalveolar space, while levels of IL-1 alpha remained low. Administration of recombinant TNF-alpha in physiological concentrations did not affect the proliferation of P. aeruginosa in vitro, but when given intratracheally to rats at the time of infection, recombinant TNF-alpha significantly increased bacterial clearance from the lungs. In these animals, phagocytic activity of bronchoalveolar neutrophils was enhanced, while the recruitment of alveolar macrophages and neutrophils remained unchanged. In acutely infected nonimmune animals, bronchoalveolar concentrations of soluble IL-1 alpha and TNF-alpha increased until the time of death. Levels of prostaglandin E2 and thromboxane B2 were similar in each experimental group. These results indicate that infection in immune animals enhanced both recruitment and phagocytic activity of alveolar macrophages as well as induced an accelerated production of TNF-alpha. In immune challenged animals, this cytokine enhanced the phagocytic activity of neutrophils and improved bacterial clearance from the lung. Levels of soluble IL-1 alpha and TNF-alpha in nonimmune rats increased consistently following infection until the time of death, thus implicating these cytokines in the pathogenesis of acute P. aeruginosa pneumonia.  相似文献   
93.
陶伟  韩卉  邓雪飞  陈方宏  庞刚  刘斌  赵红 《解剖学杂志》2007,30(3):347-350,F0003
目的:通过对上矢状窦(SSS)旁大脑桥静脉的显微解剖、影像学观察及其对照研究,为各种纵裂间手术入路中桥静脉的保护提供基础。方法:分别对30例(60侧)上矢状窦和颈内静脉内灌注蓝色乳胶的成人头颅湿标本、40侧DSA静脉相和16侧CTV进行显微解剖和影像学观察。结果:上矢状窦前部和后部分别有一缺乏桥静脉注入段,显微解剖、DSA和CTV观察上矢状窦旁桥静脉的数量分别为11.2支、8.9支和7.0支,DSA和CTV观察发现桥静脉注入上矢状窦处常显示不清。结论:熟悉和比较上矢状窦旁桥静脉的解剖学和影像学特征有利于各种纵裂间手术入路和手术过程中桥静脉的保护。  相似文献   
94.
在大鼠盲肠结扎加穿孔造成的腹膜炎败血症休克模型上发现,心肌肌膜Na^+-K^+-ATP酶活性呈双时相变化。早期休克时,Na^+-K^+-ATP酶活性比对照组高48%,晚期休克时比对照组低42%。心肌肌膜哇巴因结合位点数目和磷酸化位点数目也呈早期增加,晚期降低双时相变化。离体心脏灌流发现,败血症休克大鼠心脏的功能也呈早期增强,晚期减弱的双时相变化,而心脏对灌流硅厶因的反应性料早期增加,晚期降低。  相似文献   
95.
对铀作业者199例及无毒物接触史的正常人101例行甲襞微循环检测。结果,铀作业人员甲襞微循环有改变,其加权积分值大于对照组。主要表现在管袢数减少(P<0.01)、管径增粗(P<0.01)、毛细血管运动增加(P<0.01)、乳丛增多(P<0.01)。通过对铀致微循环改变的机理试以分析,提出这种微循环改变是铀中毒的病理表现,亦是铀中毒的重要发病环节;提示铀中毒治疗中应注重改善微循环。  相似文献   
96.
Summary The anatomic constraints imposed on a total artificial heart (TAH) require specific anatomic studies. A thoracic anatomic study was performed with a scanning device equipped with three-dimensional (3-D) reconstruction software on 15 male patients, between the ages of 41 to 63 years (52 ± 6 years). All were candidates for heart transplantation. The 3-D reconstructions of the cardiovascular structures obtained from surgical anatomy data specific to TAH implantation allowed a volumetric measurement of these structures. A modeling diagram of these structures permitted reproducible quantitative measurements of the 35 geometrical parameters which characterized shape, orientation, and position of these structures within the thorax. Most of the measured parameters were characterized by low variability (coefficient of variation from 10 to 25%).
Modélisation tridimensionnelle de l'anatomie du cur et des gros vaisseaux
Résumé Les contraintes anatomiques imposées au cur artificiel total (CAT) nécessitent des études anatomiques spécifiques. Une étude anatomique thoracique a été réalisée avec un scanner doté d'un logiciel de reconstruction tridimensionnelle (3-D) chez 15 patients, tous de sexe masculin, agés de 41 à 63 ans (52 ± 6 ans), et candidats à une transplantation cardiaque. Les reconstructions 3-D des structures cardio-vasculaires réalisées selon les données de l'anatomie chirurgicale propre à l'implantation du CAT ont permis la mesure volumétrique de ces structures. Un schéma de modélisation de ces structures a permis des mesures quantitatives reproductibles de 35 paramètres géométriques caractéristiques de la forme, de l'orientation, de la position de ces structures dans le thorax. Les résultats de ces mesures ont pu être exprimés en termes statistiques. La plupart des paramètres mesurés étaient caractérisés par une faible variabilité (coefficients de variations de 10 à 25%).
  相似文献   
97.
Antigens of virulent and attenuated Rickettsia tsutsugamushi.   总被引:1,自引:0,他引:1  
We studied the antigens present in L929 mouse fibroblast or rabbit testicular cells, which had been infected or not with a prototype strain of Rickettsia tsutsugamushi, the causal agent of scrub typhus, and its attenuated variant. Immunoblotting revealed four antigens, designated 1, 1a, 2 and 3, which appeared to be specifically associated with infection with this organism. Antigens 1 and 1a had similar mol. wt of about 60 kD and antigen 2 and 3 had mol. wts of 45 kD and 28 kD respectively. Whereas antigen 1a, 2 and 3 were common to infection with either the virulent or the attenuated strains of the organism, antigen 1 was only detected in cells infected with the virulent strain and was reactive only with the antiserum raised against cells infected with that strain. In addition, two antigens were also detected by crossed immunoelectrophoresis, one of which was similarly associated with infection with the virulent strain as antigen 1, while the other was common to infection with either of the strains. It seems that the antigenic cross reaction between the two strains may account, in part at least, for the protection of mice against infection with the virulent strain afforded by the attenuated strain, while the loss or modification of antigen 1 might be associated with attenuation of the organism with respect to its virulence to mice.  相似文献   
98.
99.
The persistence of Cytomegalovirus (CMV) with alteration of cell surface expression in certain tissues may initiate the tissue destruction that leads to the clinical manifestations of Sjogren's Syndrome. Salivary gland and lacrimal gland ductal cells are immunologically attacked due to CMV antigenic expression. The destruction of these ducts leads to xerostomia and keratonconjunctivitis sicca, the hallmarks of Sjogren's Syndrome.  相似文献   
100.
Pseudoangiomatous stromal hyperplasia (PASH) is an uncommon lesion usually found in premenopausal women. Histologically, it is characterized by complex, anatomosing, empty slit-like spaces in a dense collagenous stroma. These pseudoangiomatous spaces are lined by monomorphic spindle cells of myofibroblastic differentiation. Cytological features of PASH are rarely discussed and reported, and may pose diagnostic challenge to surgical pathologists. Two cases of PASH are reported with emphasis on the FNAC features and cytologic differentiation from other benign fibroepithelial lesions.  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