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   15456篇
  免费   1085篇
  国内免费   581篇
耳鼻咽喉   525篇
儿科学   276篇
妇产科学   90篇
基础医学   1554篇
口腔科学   486篇
临床医学   1535篇
内科学   3724篇
皮肤病学   702篇
神经病学   1263篇
特种医学   419篇
外国民族医学   2篇
外科学   1670篇
综合类   1757篇
现状与发展   1篇
一般理论   1篇
预防医学   609篇
眼科学   739篇
药学   991篇
  20篇
中国医学   348篇
肿瘤学   410篇
  2024年   53篇
  2023年   363篇
  2022年   506篇
  2021年   754篇
  2020年   684篇
  2019年   563篇
  2018年   573篇
  2017年   605篇
  2016年   545篇
  2015年   588篇
  2014年   1042篇
  2013年   1218篇
  2012年   963篇
  2011年   947篇
  2010年   769篇
  2009年   718篇
  2008年   698篇
  2007年   695篇
  2006年   567篇
  2005年   521篇
  2004年   454篇
  2003年   356篇
  2002年   310篇
  2001年   267篇
  2000年   207篇
  1999年   160篇
  1998年   180篇
  1997年   162篇
  1996年   134篇
  1995年   130篇
  1994年   112篇
  1993年   99篇
  1992年   94篇
  1991年   98篇
  1990年   87篇
  1989年   71篇
  1988年   77篇
  1987年   73篇
  1986年   55篇
  1985年   93篇
  1984年   89篇
  1983年   72篇
  1982年   80篇
  1981年   58篇
  1980年   58篇
  1979年   34篇
  1978年   34篇
  1977年   25篇
  1976年   32篇
  1973年   12篇
排序方式: 共有10000条查询结果,搜索用时 468 毫秒
81.
采用一种改进的方法,从100g猪心室肌中提取心肌肌球蛋白370mg,并进一步分离和纯化其亚基成分,分别得到肌球蛋白轻链24mg和重链210mg,核酸含量<1%,不含有肌动蛋白、原肌球蛋白、肌钙蛋白及其它杂蛋白;SDSPAGE显示,猪心肌球蛋白重链为200~220KD一条带,肌球蛋白轻链则为27kd、21.4kd、19kd三条带;纯化猪心肌球蛋白的Ca2+激活ATP酶活性为0.24μmolPi/(mg·min),但其分离后的亚基则无此活性。  相似文献   
82.
Binswanger’s disease is pathologically characterized by a combination of diffuse cerebrovascular white matter lesions and lacunar infarcts in the basal ganglia and white matter. Although a blood-brain barrier (BBB) dysfunction has been implicated in the pathogenesis of these white matter (WM) lesions, few authors have addressed this problem. In the present study, we describe BBB dysfunction and its regional differences in the brains of Binswanger’s disease patients. Twelve brains from Binswanger’s disease patients (group III) were examined and compared with those from five patients with non-neurological disease (group I) and five cortical infarct patients without significant WM lesions (group II). Immunohistochemistry was performed for glial fibrillary acidic protein and vimentin as astroglial cell markers, and for immunoglobulins, complements and fibrinogen as extravasated serum protein markers. The grading scores for IgG extravasation were significantly higher in group III as compared to group I, in both the periventricular WM and the subcortical WM (P < 0.01). In group III, the scores in the periventricular WM and subcortical WM were significantly higher than in the subcortical U fibers and cerebral cortex (P < 0.01 for the periventricular WM; P < 0.001 for the subcortical WM), respectively. Clasmatodendritic astroglia, which had swollen cell bodies and large cytoplasmic vacuoles with disintegrated processes, incorporated the serum components IgG, IgM, C3d, C1q and fibrinogen, both in the periventricular WM and subcortical WM in 5 out of 12 (42%) Binswanger’s disease brains. These results indicate that WM lesions in Binswanger’s disease are accompanied by BBB dysfunction, although it remains uncertain whether BBB dysfunction is secondary to either chronic cerebral ischemia or arterial hypertension. Received: 25 April 1997 / Revised, accepted: 21 July 1997  相似文献   
83.
κ及λ轻链测定在多发性骨髓瘤诊断中的应用   总被引:2,自引:0,他引:2  
齐为民  郭力 《医学争鸣》1998,19(4):418-420
目的:寻求准确,可靠的免疫球蛋白及κ和λ轻链测定方法,提高多发性骨髓瘤分型和鉴别诊断水平。  相似文献   
84.
Summary In order to avoid invasive procedures (transfrontal, transcallosal) in the surgical treatment of colloid cysts the stereotactic aspiration technique was introduced by Bosch, RÄhn and Backlund in 1978. The viscosity of the intracystic colloid and the displacement of the cyst away from the aspiration needle are possible reasons for unsuccessful aspiration. GT-guided stereotactic endoscopic technique gives the opportunity to fenestrate the cyst wall under direct visual control.After CT-guided stereotactic puncture of the right lateral ventricle with the foramen of Monro as target a steerable endoscope is introduced and the foramen of Monro is passed. The wall of the cyst is fenestrated and coagulated by means of monopolar (or laser) coagulation.Using this technique we have treated four patients with colloid cysts. Immediately postoperatively all of them were relieved of their complaints and have been symptomfree for a mean follow up period of twelve months. Studies of cerebrospinal fluid flow patterns, performed prior to and every six months after the endoscopic intervention, confirmed a remarkable reduction of foraminal obstruction.  相似文献   
85.
86.
We previously reported the hyperosmolarity response (a decrease of the ocular standing potential by hyperosmolarity) as a new clinical test of the retinal pigment epithelium (RPE) activity. In the present study a hypertonic solution (Fructmanit, 1.4 × 103 m0sm/1) was intravenously injected for 20 min in proportion to a subject's total blood volume (TBV). At the injection speed of 5, 10, and 15% of the subjects' TBV per hour the mean amplitude of the hyperosmolarity response in normal subjects was 19.7, 30.1 and 36.4% respectively. The amplitude of the hyperosmolarity response depends on the logarithm of the dose of the hypertonic solution within the range of the dose tested.We previously found that hyperosmolarity suppresses the light rise. The present study investigated this suppressive effect in a quantitative manner. The light rise (a full-field illumination of 1.2 × 103 cdl/m2) was dose-dependently suppressed by Fructmanit. The mean of the light rise to dark trough ratio in normal subjects was 1.81 with no osmotic stress, and 1.64, 1.41 and 1.29 respectively at the injection speeds of 5, 10, and 15%. The suppression of the light rise by hyperosmolarity is compatible with the view that the hyperosmolarity response and the light rise share the basal membrane of the RPE as the main site of their generation.  相似文献   
87.
While conventional magnetic resonance imaging (MRI) measures signal primarily from the hydrogen nuclei of water, magnetization transfer (MT) MRI indirectly detects macromolecular associated hydrogen nuclei via their magnetic interaction with the observable water. In the normal adult CNS, white matter exhibits the largest MT effect due to the macromolecular content of the highly structured and lipid rich myelin. Pathologies which alter the structural integrity and the relative macromolecular-water composition, such as multiple sclerosis (MS), therefore show abnormal MT. Conventional MRI, which has a high MS lesion detection sensitivity but poor specificity in terms of differentiating the pathological state of a plaque, can thus be supplemented by MT to provide more specific information on the extent of demyelination and axonal loss. In this paper we review the basic concepts of MT imaging and its role in MS lesion characterization.Financial support was provided by the Medical Research Council of Canada, Fonds de la Recherche en Santé du Québec, and the Killam Foundation.  相似文献   
88.
目的:临床观察纵隔镜检查在胸部疑难疾病诊断中的作用。方法:使用德国STORZ公司生产的纵隔镜,对17例临床不能确诊的影像学检查发现的纵隔肿物或淋巴结施行标准的经颈纵隔镜检查术。结果:本组均获得了明确的病理诊断,其中良性病变88.2%(15/17),包括结节病9例,淋巴结结核5例,巨大淋巴结增生症1例,而2例恶性肿物均为肺小细胞未分化癌。结论:纵隔镜对原因不明的纵隔肿物或结节的诊断有着重要意义,可使一些结节病或淋巴结结核的患者得到及时正确的诊断,使这部分患者避免了盲目的试验性放、化疗或开胸探查所带来的痛苦。  相似文献   
89.
内镜下卢戈液染色诊断早期食管癌   总被引:3,自引:0,他引:3  
目的:研究内镜下卢戈液染色诊断早期食管癌的临床可行性。方法:168例患者经内镜下喷洒卢戈氏液对食管粘膜染色后观察,并取不染区组织进行病理检查。结果:168例患者中有123例食管粘膜呈不规则片状不染或着色不良,经病理检查发现食管鳞癌16例,腺癌4例,各种程度的不典型增生52例,不同程度的炎症51例。正常着色者25例,深染者14例与散在小点状着色不良者6例中病理结果为轻度慢性炎症35例,未见明显异常者10例。结论:内镜下卢戈液染色是提高食管癌及癌前病变检出率的有效方法。  相似文献   
90.
Seven cases of carcinoma mimicking angiosarcoma occurring in skin (3 cases), breast (3) and lung (1) are described. The cutaneous, pulmonary and one of the breast carcinomas were poorly differentiated and squamous in type; the other two breast tumours were poorly differentiated ductal carcinomas with focal squamous differentiation. Histologically, the pseudoangiosarcomatous pattern was due to complex anastomosing channels and spaces lined by neoplastic cells. The spaces contained hyaluronic acid. The neoplastic cells exhibited cytokeratin positivity but yielded negative results with the endothelial cell markers, factor VIII-related antigen and CD 34 (QB-END/10). Two breast tumours showed binding of UEA-1. Ultrastructurally, unequivocal epithelial differentiation was demonstrated in six of the cases. Pathogenetically, these tumours appeared to be variants of acantholytic squamous cell carcinoma. Recognition of this unusual form of carcinoma is important, as an incorrect diagnosis of angiosarcoma may lead to inappropriate treatment and prognostication.  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