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   68655篇
  免费   5878篇
  国内免费   2724篇
耳鼻咽喉   692篇
儿科学   1824篇
妇产科学   1351篇
基础医学   6538篇
口腔科学   1162篇
临床医学   7101篇
内科学   6394篇
皮肤病学   800篇
神经病学   2289篇
特种医学   3919篇
外国民族医学   53篇
外科学   9408篇
综合类   11645篇
现状与发展   20篇
预防医学   2074篇
眼科学   607篇
药学   4714篇
  58篇
中国医学   2273篇
肿瘤学   14335篇
  2024年   182篇
  2023年   1054篇
  2022年   2273篇
  2021年   3001篇
  2020年   2433篇
  2019年   2153篇
  2018年   2008篇
  2017年   2265篇
  2016年   2536篇
  2015年   2716篇
  2014年   4228篇
  2013年   4315篇
  2012年   3825篇
  2011年   4267篇
  2010年   3432篇
  2009年   3453篇
  2008年   3406篇
  2007年   3701篇
  2006年   3340篇
  2005年   2958篇
  2004年   2568篇
  2003年   2136篇
  2002年   1977篇
  2001年   1775篇
  2000年   1447篇
  1999年   1324篇
  1998年   1122篇
  1997年   1047篇
  1996年   916篇
  1995年   832篇
  1994年   687篇
  1993年   547篇
  1992年   446篇
  1991年   375篇
  1990年   297篇
  1989年   275篇
  1988年   281篇
  1987年   230篇
  1986年   173篇
  1985年   238篇
  1984年   212篇
  1983年   124篇
  1982年   167篇
  1981年   136篇
  1980年   93篇
  1979年   92篇
  1978年   66篇
  1977年   46篇
  1976年   40篇
  1975年   15篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
Our aim was to develop an accurate multispectral tissue segmentation method based on 3D feature maps. We utilized proton density (PD), T2-weighted fast spin-echo (FSE), and T1-weighted spin-echo images as inputs for segmentation. Phantom constructs, cadaver brains, an animal brain tumor model and both normal human brains and those from patients with either multiple sclerosis (MS) or primary brain tumors were analyzed with this technique. Initially, misregistration, RF inhomogeneity and image noise problems were addressed. Next, a qualified observer identified samples representing the tissues of interest. Finally, k-nearest neighbor algorithm (k-NN) was utilized to create a stack of color-coded segmented images. The inclusion of T1 based images, as a third input, produced significant improvement in the delineation of tissues. In MS, our 3D technique was found to be far superior to that based on any combination of 2D feature maps (P < 0.001). We identified at least two distinctly different classes of lesions within the same MS plaque, representing different stages of the disease process. Further, we obtained the regional distribution of MS lesion burden and followed its changes over time. Neuropsychological aberrations were the clinical counterpart of the structural changes detected in segmentation. We could also delineate the margins of benign brain tumors. In malignant tumors, up to four abnormal tissues were identified: 1) a solid tumor core, 2) a cystic component, 3) edema in the white matter, and 4) areas of necrosis and hemorrhage. Subsequent neurosurgical exploration confirmed the distribution of tissues as predicted by this analysis.  相似文献   
92.
泪腺肿瘤中P53蛋白表达的意义   总被引:4,自引:0,他引:4  
目的了解P53基因在泪腺肿瘤的表达及其临床病理学意义。方法应用免疫组织化学ABC法检测57例泪腺上皮性肿瘤患者和10例正常人泪腺组织中P53蛋白的表达情况,并与病理分级、复发相联系。结果10例正常人泪腺组织中P53表达全部为阴性;恶性肿瘤患者的表达率为48.6%,良性肿瘤中P53达率为18%,二者相比有显著性差异(P<0.025);复发患者阳性率为76.9%,明显高于未复发患为31.8%(P=0.015)。结论P53基因参与了泪腺肿瘤的发生发展并与肿瘤的分化和复发有关。  相似文献   
93.
This article reviews the author's experience with a form of interposed abdominal compression cardiopulmonary resuscitation (IAC-CPR) in the United Kingdom. The development of the technique based upon animal resuscitation, including the use of phasic compression (abdominal pumping) for the resuscitation of rats from 30 minutes of cardiac arrest due to hypothermia, is reviewed. A simple technique for clinical use is described. The technique uses a hard-covered book or bean-shaped board applied to the abdomen below the umbilicus and compressed alternately with cardiac massage while respiration is assisted. Anecdotal clinical results suggest that further controlled clinical investigation is warranted.  相似文献   
94.
95.
总结我院12年来的12例肺血管瘤的资料,结合文献讨论了肺血管瘤的临床特点,如:女性多见,可有呼吸系统症状,X线多表现为孤立性病灶及生长缓慢等。准确诊断较难,手术治疗预后良好。应进一步加深临床对该病的认识。  相似文献   
96.
Temporary closure of the abdominal wall (laparostomy)   总被引:2,自引:0,他引:2  
The definitive closure of the abdominal wall, i.e., a closure of the fascial layer and skin may not be favorable in the treatment of numerous surgical conditions, e.g., peritonitis, trauma, or mesenteric ischemia. In these cases, the abdominal wall is temporarily closed, and a laparostomy is created to facilitate re-exploration or to prevent abdominal compartment syndrome. Regarding the technique and material used for the temporary closure, no prospective randomized data exists, but mesh materials are commonly used. They provide drainage of infectious material, permit visual control of the underlying viscera, facilitate access to the abdominal wall, preserve the fascial margin, enable healing by secondary intention, and allow mobilization of the patient. In the case of decreasing intra-abdominal pressure, meshes can be trimmed to centralize the rectus muscle and to facilitate definitive closure. Non-absorbable meshes have been frequently reported to cause enteric fistulae and persistent infection necessitating mesh explantation. While these infectious complications appear to occur less frequently with the use of absorbable materials, these meshes will finally lead to an incisional hernia, requiring repair with non-absorbable mesh after a period of 6–12 months. Nevertheless, in the complex situation requiring a temporary abdominal wall closure, use of absorbable mesh material is common and represents the state of the art. Electronic Publication  相似文献   
97.
Department of Biology, Medico-Biological Faculty, and Applied Research Laboratory of Ecology, Toxicology, and Metabolism of Medicinal Preparations, attached to the Department of Biochemistry, Medico-Biological Faculty, N. I. Pirogov Second Moscow Medical Institute. Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 112, No. 10, pp. 418–419, October, 1991.  相似文献   
98.
Pulmonary Function in Survivors of Wilms' Tumor   总被引:1,自引:0,他引:1  
The respiratory status of 47 patients surviving childhood Wilms' tumor was studied. The group that had receivedflnnk irradiation (which impinges on the lower lung) (n - 17) had a sisnijGantly lower mean percent predicted for forced expiratory volume in one second, residual volume, and total lung capaci(v when compared to those who had received no irradiation (n - 23). Those patients who had received whole-lung irradiation (n - 3) had sisnijicantly lower transfn. foctor for carbon monoxide and gas transfer per unit lung volume whm compared to the nonirradiated group (n - 23). There was no sipiftiant dimue in the prevalence of respiratory symptoms between the three groups. Patients receiving any form of radiotherapy for Wilms' tumor may have abnormulities o f pulmonary function and should have pulmonary function tests performed as part o f their long-tmn follow-up.  相似文献   
99.
神经导航辅助显微手术治疗脑功能区肿瘤   总被引:6,自引:2,他引:4  
目的探讨神经导航系统辅助下脑重要功能区肿瘤显微手术的治疗效果和应用价值。方法1999年12月~2002年6月应用StealthStation神经导航系统辅助切除邻近脑重要功能区肿瘤10例,对神经导航系统术中应用的优越性、精确性等进行分析。结果本组平均注册误差为(2.8±0.9)mm,肿瘤和重要解剖功能结构定位准确,肿瘤全切除率77.8%。术后神经功能未受明显影响,无手术并发症及死亡。结论神经导航系统对于切除邻近脑重要功能区肿瘤具有定位准确,动态示踪和实时导航,侵袭性小,安全、可靠等特点,有助于提高肿瘤全切率及降低手术并发症。  相似文献   
100.
李凤仙  魏文 《癌症》1994,13(3):206-210
用逐步递增药物浓度和软琼脂细胞克隆技术,药物连续作用14个月后获得氮芥(HN2)抗药性人早幼粒白血病HL60细胞亚系,抗件达5~7倍(HL60/NH26),在无HN2培养液中5倍以上抗性维持10个月以上,抗性细胞亚系的生物学特性除倍增时间稍长和克隆形成率略低外其生长曲线,细胞周期细胞DNA指数,形态学,组织化学和染色体分析均与亲代细胞相似。  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