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   26174篇
  免费   1449篇
  国内免费   63篇
耳鼻咽喉   409篇
儿科学   1108篇
妇产科学   871篇
基础医学   4240篇
口腔科学   582篇
临床医学   2146篇
内科学   5202篇
皮肤病学   533篇
神经病学   2579篇
特种医学   1099篇
外国民族医学   14篇
外科学   3768篇
综合类   121篇
一般理论   3篇
预防医学   1365篇
眼科学   499篇
药学   1365篇
中国医学   19篇
肿瘤学   1763篇
  2022年   172篇
  2021年   358篇
  2020年   237篇
  2019年   324篇
  2018年   415篇
  2017年   348篇
  2016年   487篇
  2015年   473篇
  2014年   640篇
  2013年   823篇
  2012年   1183篇
  2011年   1256篇
  2010年   624篇
  2009年   677篇
  2008年   1150篇
  2007年   1236篇
  2006年   1155篇
  2005年   1183篇
  2004年   982篇
  2003年   978篇
  2002年   901篇
  2001年   904篇
  2000年   932篇
  1999年   787篇
  1998年   355篇
  1997年   274篇
  1996年   232篇
  1995年   209篇
  1994年   188篇
  1993年   185篇
  1992年   482篇
  1991年   507篇
  1990年   490篇
  1989年   408篇
  1988年   390篇
  1987年   404篇
  1986年   393篇
  1985年   391篇
  1984年   273篇
  1983年   217篇
  1982年   139篇
  1981年   145篇
  1979年   262篇
  1978年   184篇
  1977年   157篇
  1976年   153篇
  1975年   165篇
  1974年   192篇
  1973年   167篇
  1972年   154篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
51.
A series of substituted indolyldihydropyridazinones and related compounds 1-18 were synthesized and evaluated for positive inotropic activity. In rats, most of these indole derivatives produced a dose-related increase in myocardial contractility with little effect on heart rate and blood pressure. Compound 13, 4,5-dihydro-5-methyl-6-(2-pyridin-4-yl-1H-indol-5-yl)pyrazin-3(2H) -one (BM 50.0430), was further investigated in cats. The increase in contractility in this animal model was not mediated via stimulation of beta-adrenergic receptors. After oral administration of 1 mg/kg to conscious dogs, compound 13 and pimobendan were still active after 6.5 h. However, the cardiotonic effect of 13 was at least 2-fold that of pimobendan after this period of time. The structural requirements necessary for optimal cardiotonic activity within this novel class of indole derivatives are a heterocyclic aromatic ring in position 2, a hydrogen or a methyl group in position 3, and a dihydropyridazinone ring system in position 5 of the indole.  相似文献   
52.
Ciclesonide is an onsite-activated inhaled corticosteroid (ICS) for the treatment of asthma. This study compared the efficacy, safety and effect on quality of life (QOL) of ciclesonide 160 microg (ex-actuator; nominal dose 200 microg) vs. budesonide 400 microg (nominal dose) in children with asthma. Six hundred and twenty-one children (aged 6-11 yr) with asthma were randomized to receive ciclesonide 160 microg (ex-actuator) once daily (via hydrofluoroalkane metered-dose inhaler and AeroChamber Plus spacer) or budesonide 400 microg once daily (via Turbohaler) both given in the evening for 12 wk. The primary efficacy end-point was change in forced expiratory volume in 1 s (FEV1). Additional measurements included change in daily peak expiratory flow (PEF), change in asthma symptom score sum, change in use of rescue medication, paediatric and caregiver asthma QOL questionnaire [PAQLQ(S) and PACQLQ, respectively] scores, change in body height assessed by stadiometry, change in 24-h urinary cortisol adjusted for creatinine and adverse events. Both ciclesonide and budesonide increased FEV1, morning PEF and PAQLQ(S) and PACQLQ scores, and improved asthma symptom score sums and the need for rescue medication after 12 wk vs. baseline. The non-inferiority of ciclesonide vs. budesonide was demonstrated for the change in FEV1 (95% confidence interval: -75, 10 ml, p = 0.0009, one-sided non-inferiority, per-protocol). In addition, ciclesonide and budesonide showed similar efficacy in improving asthma symptoms, morning PEF, use of rescue medication and QOL. Ciclesonide was superior to budesonide with regard to increases in body height (p = 0.003, two-sided). The effect on the hypothalamic-pituitary-adrenal axis was significantly different in favor of ciclesonide treatment (p < 0.001, one-sided). Both ciclesonide and budesonide were well tolerated. Ciclesonide 160 microg once daily and budesonide 400 microg once daily were effective in children with asthma. In addition, in children treated with ciclesonide there was significantly less reduction in body height and suppression of 24-h urinary cortisol excretion compared with children treated with budesonide after 12 wk.  相似文献   
53.
54.
55.
A patient with group B streptococcal endocarditis and large vegetations resembling mitral valve myxoma is described. Group B streptococcal endocarditis and the differential diagnosis of vegetations and cardiac tumors are briefly reviewed.  相似文献   
56.
Metastatic bone disease from occult carcinoma: a profile   总被引:3,自引:0,他引:3  
Summary To assess the general profile of metastatic bone disease from occult primary carcinoma, the records of 172 patients with skeletal metastases seen between 1965 and 1985 were reviewed. In 51 patients (30%), the origin of the primary could not be identified when bone metastases were first diagnosed. This group were predominantly male with a high incidence of spinal metastases, cord compression and pathological fractures, and a significantly shorter (P<0.1) survival compared with bony metastases when the primary was known. The site of the primary was established in 33 patients (65%), mostly at autopsy. Lung carcinoma was by far the most common primary tumour in 52% of the cases, while it accounted for only 7% of those with a diagnosed primary. We believe that the onset of bony metastases from an occult source must initially raise the possibility of lung carcinoma. If the primary remains undetected, it appears justifiable to assume it to be in the lung, since the probability of a missed lung tumour being responsible for the metastases is high.
Résumé Les auteurs ont revu les observations de 172 malades porteurs de métastases osseuses, vus entre 1965 et 1985, afin d'apprécier l'aspect général des métastases provenant d'un cancer primitif méconnu. Chez 51 malades (30%) l'origine du cancer primitif n'avait pu être découverte lors du diagnostic de métastase osseuse. Ce groupe était à prédominance masculine, comportant un nombre élevé d'atteintes vertébrales, de compressions médullaires et de fractures pathologiques, et un taux de survie significativement plus court (P<0,1) comparativement à celui des métastases d'un cancer primitif connu. La localisation du cancer primitif a été découverte dans 33 cas (65%), la plupart du temps à l'autopsie. Le cancer du poumon était le plus fréquemment en cause (52%), alors qu'il n'était responsable que de 7% des cas quand le cancer primitif était connu. Il semble que l'apparition de métastases osseuses d'origine inconnue doive faire évoquer d'emblée la possibilité d'un cancer du poumon. Si le cancer primitif ne peut être découvert il est vraisemblable qu'il siège au niveau du poumon, la probabilité d'un cancer du poumon méconnu, responsable des métastases, étant élevée.


Presented in part at the International Symposium on Bone Metastases, Rome, Italy, June 1986  相似文献   
57.
58.
59.
Targeting proteins that are overexpressed in atherosclerotic plaques may open novel diagnostic applications. The C domain of tenascin-C is absent from normal adult tissues but can be inserted during tumor progression or tissue repair into the molecule by alternative splicing. We tested the ability of the human antibody G11, specific to this antigen, to reveal murine atherosclerotic plaques ex vivo. The antibody directed against the extra domain B of fibronectin (L19) was used as a reference. METHODS: We intravenously injected (125)I-labeled G11 or L19 antibodies into apolipoprotein E-deficient (ApoE(-/-)) mice and harvested the aortae 4 or 24 h later. En face analyses of distal aortae and longitudinal sections of the aortic arch were performed to compare antibody uptake using autoradiography with plaque staining using oil red O. Plaque macrophages were detected by immunohistochemistry (anti-CD68 staining). Biodistribution of injected antibodies was investigated in aortae and blood at 4 and 24 h. RESULTS: En face analyses revealed a significant correlation between radiolabeled G11 and fat-stained areas, increasing from 4 to 24 h, with a correlation coefficient of 0.92 (P < 0.0001) and an average signal-to-noise ratio of 104:1 at 24 h. Plaque imaging using L19 showed similar results (r = 0.86; P < 0.0001; signal-to-noise ratio, 72:1 at 24 h). Uptake of radiolabeled antibodies in histologic sections colocalized with fat staining and activated macrophages in aortic plaques. Biodistribution analyses confirmed specific accumulation in aortic plaques as well as rapid blood pool clearance of the antibodies 24 h after injection. Immunofluorescence analyses revealed increased expression of tenascin and fibronectin isoforms in macrophage-rich plaques. CONCLUSION: The antibody G11, specific to the C domain of tenascin-C, visualizes murine atherosclerotic plaques ex vivo. In conjunction with the increased expression of the C domain of tenascin-C in macrophage-rich plaques, the colocalization of G11 uptake with activated macrophages, and the favorable target-to-blood ratio at 24 h, this antibody may be useful for molecular imaging of advanced atherosclerotic plaques in the intact organism.  相似文献   
60.
Waldenstrom's macroglobulinemia (WM) is an uncommon low-grade lymphoma. Cognitive impairment due to central nervous system infiltration by lymphoplasmocytoid cells (Bing-Neel syndrome) has been rarely reported. We describe a 54-year-old man who was referred to a memory disorder clinic with a 9-month history of clinically obvious nonfluent aphasia and WM. He underwent extensive neuropsychological testing, clinical examination and structural and functional brain imaging. The diagnosis of the diffuse form of the Bing-Neel syndrome was supported by abnormal lymphoid cells found in the cerebrospinal fluid. Structural and functional brain imaging revealed impairment of brain areas due to white matter changes and subsequent functional deficits mimicking the neuropsychological syndrome encountered in progressive nonfluent aphasia. The diffuse form of Bing-Neel syndrome and neurological deficits are assumed to be the result of leptomeningeal infiltration by malignant cells and/or neoplastic vascular obstruction.  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