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   66151篇
  免费   4715篇
  国内免费   2247篇
耳鼻咽喉   430篇
儿科学   1591篇
妇产科学   787篇
基础医学   9659篇
口腔科学   907篇
临床医学   4905篇
内科学   10408篇
皮肤病学   1313篇
神经病学   5084篇
特种医学   929篇
外国民族医学   13篇
外科学   6014篇
综合类   6808篇
现状与发展   11篇
预防医学   5096篇
眼科学   1065篇
药学   10781篇
  8篇
中国医学   3275篇
肿瘤学   4029篇
  2023年   955篇
  2022年   1739篇
  2021年   2168篇
  2020年   1983篇
  2019年   2691篇
  2018年   2618篇
  2017年   2181篇
  2016年   2045篇
  2015年   2253篇
  2014年   3773篇
  2013年   4298篇
  2012年   3596篇
  2011年   4417篇
  2010年   3696篇
  2009年   3077篇
  2008年   2891篇
  2007年   2782篇
  2006年   2371篇
  2005年   2060篇
  2004年   1844篇
  2003年   1696篇
  2002年   1372篇
  2001年   1178篇
  2000年   895篇
  1999年   910篇
  1998年   736篇
  1997年   688篇
  1996年   585篇
  1995年   516篇
  1994年   459篇
  1993年   431篇
  1992年   387篇
  1991年   368篇
  1990年   319篇
  1989年   256篇
  1988年   251篇
  1986年   191篇
  1985年   846篇
  1984年   1071篇
  1983年   851篇
  1982年   978篇
  1981年   906篇
  1980年   694篇
  1979年   657篇
  1978年   461篇
  1977年   375篇
  1976年   430篇
  1975年   331篇
  1974年   208篇
  1973年   206篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
对150例IgA肾病的肾活检标本进行了光镜及透射电镜的形态学观察,[其组织学改变由轻微病变至弥漫性系膜增殖,根据病变的严重程度作者将其分为6个亚型。系膜基质的增生为其突出的超微结构改变,常显示为局灶节段性、球性系膜细胞增殖和显著的系膜基质的增加。电子致密沉着多见于系膜基质及内皮细胞下,这些沉着物的多少与病变的严重程度未见有肯定的联系。  相似文献   
92.
用荧光分光光度法检测了血清单胺氧化酶(MAO)同工酶A(MAO-A)和同工酶B(MAO-B)活性,结果表明血清MAO-B活性急性期甲肝组较正常对照组显著升高,慢性期乙肝极显著升高;二型肝炎组的MAO-A活性升高程度无统计学意义。二型肝炎MAO同工酶活性改变与其它肝功生化指标无明显相关性,表现血清MAO同工酶活性与肝功损害程度不相关。  相似文献   
93.
对我院1992年1月到1994年6月间应用KS—2A型特效癌症治疗仪治疗宫颈病变905例进行疗效分析,总的一次治愈率为97%,治疗宫颈糜烂858例,有效率100%,一次治愈率为97.4%,与冷冻治疗相比差异有显著性(P<0.001).治疗宫颈腺体囊肿34例,治愈率为84.5%.提示:与其它治疗方法相比,KS仅治疗具有治愈率高,副作用少,愈合时问短,操作简单,患者无痛苦等特点,具有推广和普及的价值.  相似文献   
94.
Hu Zhen  et al.   《中国公共卫生学报》1994,13(3):164-166
近些年来对A群多糖脑膜炎菌苗最适免疫剂量进行了一系列现场流行病学及血清学效果的对比研究。首先肯定了我国生产的菌苗与法国Merieux研究所生产的苗苗在人体接种后观察一年内具有同等杀菌抗体反应。以后在严格对比下观察了国内生产的多糖菌苗接种30μg及50μg一年内的血清杀菌抗体反应。结果完全相同;而全身反应则30μg为50μg剂量的五分之一。在我国80年代流脑流行地区内确证了30μg免后人群保护率为99%与国外50μg的保护率(97.2%)相似。国内连续三年在流行地区内对比观察了30μg、与50μg的流行病学预防效果,其人群保护率相似.与国外(Reingold).的报告亦相似。最后结论是本菌苗的最适免疫剂量为30μg.不但其预防效果与50μg相同,而且菌苗反应轻微,经济效益高,有利于在发展中国家推广使用。  相似文献   
95.
Effect of cyclosporin a on proteinuria in patients with Alport's syndrome   总被引:1,自引:0,他引:1  
Eight patients with Alport's syndrome and massive proteinuria (129±60.57 mg/m2 per hour) were treated with cyclosporin A (CyA) for 8 months. The average dose of CyA administered to all patients was 4.21±0.26 mg/kg per day and blood CyA levels of 63.4±4.1 ng/ml were attained. In five patients, proteinuria abated during the 3rd week of treatment. In the remaining three, all of whom had low creatinine clearance (82.0, 46.0 and 43.2 ml/min per 1.73 m2 respectively), proteinuria persisted but at levels lower than before treatment: 32.5±15.9 mg/m2 per hour versus 183.3±29.7 mg/m2 per hour. No permanent decrease in creatinine clearance was observed in any of these patients throughout treatment. In those patients in whom proteinuria abated, it reappeared 2 weeks after discontinuation of CyA treatment. We observed no significant increases in angiotensin II plasma levels in our patients during CyA administration. Although we have shown that CyA will reduce massive proteinuria in patients with Alport's syndrome, we cannot yet recommend its use as a therapeutic measure.  相似文献   
96.
Gingival hyperplasia is a common side-effect of immunosuppression with cyclosporine A. Nifedipine is often used to control hypertension in kidney graft recipients. Analysis of gingival status in 106 children transplanted at our centre, and treated either with azathioprine, cyclosporine A or both, revealed significantly higher degrees of gingival overgrowth in those children receiving a combination of cyclosporine A and nifedipine compared with those children treated with cyclosporine A or nifedipine alone. Seven children undergoing gingivectomy at our centre over the past few years had received this combination. After a change in the antihypertensive regimen, avoiding long-term nifedipine medication, and improved dental care with chlorhexidine gel, we noted a reduction in the degree of gingival hyperplasia. In the majority of patients, nifedipine could be replaced by a single drug, usually hydralazine. We therefore recommend avoiding calcium channel blockers in the long-term management of hypertension in patients receiving cyclosporine.  相似文献   
97.
the feasibility of using chemosensitizers in the circumvention of P-glycoprotein-mediated multidrug resistance has been shown in many studies. We recently reported on the chemosensitizing effect of cyclosporin A (CsA) on doxorubicin in a rat solid tumour model. Using the same experimental design we investigated the side-effects of the combination treatment. During the 35-day experiment doxorubicin treatment caused dose-dependent weight loss, which was enhanced by combination treatment with CsA. The main doxorubicin-related side-effects were myelosuppression (transient leucopenia and thrombopenia) and nephrotoxicity. Damage to the kidney was severe, leading to a nephrotic syndrome and resulting in ascites, pleural effusion, hypercholesterolaemia and hypertriglyceridaemia. These toxicities were enhanced by the addition of the chemosensitizer CsA. Mild doxorubicin-related cardiomyopathy and minimal hepatotoxicity were seen on histological examination. There were no signs of enhanced toxicity of the combination treatment in tissues with known high expression levels of P-glycoprotein, like the liver, adrenal gland and large intestine. CsA had a low toxicity profile, as it only caused a transient rise in bilirubin. In conclusion, the chemosensitizer CsA enhanced the side-effects of the anticancer drug doxorubiein without altering the toxicity pattern. There was no evidence of a therapeutic gain by adding CsA to doxorubicin, compared to single-agent treatment with doxorubicin in 25%–33% higher doses, because of the enhanced toxicity of the combination treatment.Abbreviations CsA cyclosporin A - DOX doxorubicin - MDR multidrug resistance - PBS phosphate-buffered saline This work was supported by the Dr Daniël den Hoed Foundation, Rotterdam, The Netherlands  相似文献   
98.
OBJECTIVES: The purpose of this study was to determine the clinical and biophysical characteristics of a novel SCN5A mutation. BACKGROUND: Brugada syndrome and isolated cardiac conduction defect have been linked to SCN5A mutations. METHODS: Eleven members of a western European family underwent electrophysiologic investigations and mutation analysis of the SCN5A gene. Wild-type and mutant SCN5A channels were expressed in HEK293 cells, and whole cell currents were studied using patch clamp procedures. RESULTS: A novel mutation, R376H, in the first pore segment of SCN5A variably causes Brugada syndrome and/or conduction disease in a single family. Biophysical analysis demonstrated a significant current reduction for the mutant, a pathophysiologic profile consistent with Brugada syndrome and isolated cardiac conduction defect. Among 11 family members, 9 were carriers of the mutation. The proband's initial presentation was a saddleback Brugada ECG, atrial flutter, and diffuse conduction disturbances. He had no inducible ventricular arrhythmias but experienced sudden cardiac death. His brother was affected by atrial flutter and had a clear conduction disorder, but he did not display baseline or evocable ECG signs of Brugada syndrome. He received an implantable cardioverter-defibrillator that delivered one appropriate shock after 1 year of follow-up. The phenotype in the family members was highly variable and ranged from noninducible and inducible asymptomatic carriers of the mutations to isolated conduction disease and to symptomatic Brugada syndrome. CONCLUSIONS: We describe the functional characterization of a novel SCN5A pore mutation, R376H, with variable clinical expression in the same family. Differentiating between electrophysiologic entities (Brugada syndrome-isolated cardiac conduction defect) is more challenging. Recognition of factors modifying the clinical presentation may be important for clinical decision making.  相似文献   
99.
目的 研究皮质类固醇激素调节小鼠哮喘模型树突细胞表面共刺激分子表达的机制,以及肺表面活性蛋白A(SP-A)在其调节中的作用。方法 BALB/c小鼠30只,分为3组:哮喘组,采用卵蛋白(OVA)致敏和激发;对照组,以生理盐水代替OVA;治疗组,每次OVA激发后10min,腹腔注射地塞米松01mg。用免疫组化法检测SP-A在肺内的表达情况。采用Leica DM Snk软件进行图像采集,并用Qwin软件计算小气道内棕色区域面积,取平均值,进行统计分析。分离培养脾脏树突细胞,用流式细胞仪(FACS)检测树突细胞表面共刺激分子CD80的表达变化。结果 哮喘组肺组织表现为嗜酸性细胞及淋巴细胞浸润为主的炎症变化,治疗组和对照组无此变化。哮喘组的SP-A表达明显低于对照组和治疗组(P〈0.01),CD80的表达率明显高于治疗组(P〈0.01);哮喘组小气道内SP-A表达与树突细胞CD80阳性率呈负相关(r=-0.907,P〈0.01)。结论 皮质类固醇对小鼠哮喘模型的肺表面活性蛋白有明显的保护作用,可通过激发肺表面活性蛋白抑制树突细胞表面共刺激分子CD80的表达。  相似文献   
100.
Summary.  Patients with mild or moderate haemophilia A usually have a mild bleeding disorder requiring only occasional treatment with factor VIII (FVIII) concentrates. The frequency of inhibitor development in such patients has been the subject of several recent surveys, which significantly modified our appreciation of this complication. Studies of the anti-FVIII antibodies provided an explanation for the different bleeding phenotypes observed in mild/moderate haemophilia A patients with inhibitors. Antibodies distinguishing between the patient's mutant FVIII and the normal wild-type FVIII were characterized, in addition to antibodies inhibiting completely or only partially FVIII activity. T lymphocytes recognizing FVIII and likely involved in the development of the immune response to FVIII were successfully identified. The FVIII peptides recognized by those FVIII-specific cells bind to many major histocompatibility complex (MHC) class II molecules, which may provide an explanation for the lack of strong association between MHC haplotypes and inhibitor development. Although these studies have advanced our understanding of the conditions leading to inhibitor development, further work is required to determine whether the mode of FVIII administration significantly influences inhibitor development. Further studies of the genetic factors are also required to fully understand the mechanisms leading to inhibitor development in patients with mild/moderate haemophilia A.  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