全文获取类型
收费全文 | 88093篇 |
免费 | 8010篇 |
国内免费 | 6202篇 |
专业分类
耳鼻咽喉 | 587篇 |
儿科学 | 990篇 |
妇产科学 | 1095篇 |
基础医学 | 10784篇 |
口腔科学 | 1559篇 |
临床医学 | 11693篇 |
内科学 | 13266篇 |
皮肤病学 | 989篇 |
神经病学 | 4571篇 |
特种医学 | 3029篇 |
外国民族医学 | 44篇 |
外科学 | 9073篇 |
综合类 | 15235篇 |
现状与发展 | 21篇 |
一般理论 | 8篇 |
预防医学 | 5743篇 |
眼科学 | 2302篇 |
药学 | 9122篇 |
97篇 | |
中国医学 | 4917篇 |
肿瘤学 | 7180篇 |
出版年
2024年 | 300篇 |
2023年 | 1496篇 |
2022年 | 3595篇 |
2021年 | 4538篇 |
2020年 | 3296篇 |
2019年 | 2940篇 |
2018年 | 3007篇 |
2017年 | 2579篇 |
2016年 | 2562篇 |
2015年 | 3847篇 |
2014年 | 4755篇 |
2013年 | 4181篇 |
2012年 | 6141篇 |
2011年 | 7086篇 |
2010年 | 4300篇 |
2009年 | 3372篇 |
2008年 | 4560篇 |
2007年 | 4631篇 |
2006年 | 4706篇 |
2005年 | 4378篇 |
2004年 | 2967篇 |
2003年 | 2908篇 |
2002年 | 2461篇 |
2001年 | 2172篇 |
2000年 | 2264篇 |
1999年 | 2363篇 |
1998年 | 1490篇 |
1997年 | 1540篇 |
1996年 | 1163篇 |
1995年 | 1064篇 |
1994年 | 906篇 |
1993年 | 562篇 |
1992年 | 732篇 |
1991年 | 622篇 |
1990年 | 529篇 |
1989年 | 461篇 |
1988年 | 398篇 |
1987年 | 347篇 |
1986年 | 301篇 |
1985年 | 215篇 |
1984年 | 137篇 |
1983年 | 95篇 |
1982年 | 56篇 |
1981年 | 66篇 |
1980年 | 46篇 |
1979年 | 69篇 |
1977年 | 16篇 |
1973年 | 11篇 |
1972年 | 10篇 |
1971年 | 9篇 |
排序方式: 共有10000条查询结果,搜索用时 13 毫秒
81.
本文综述常用抗偏头痛药物的药理学特点及临床应用。新药舒马坦具有理想的选择性抗偏头痛活性,布托啡烷等的经鼻喷雾用药系统为以前不能接受治疗的偏头痛患者提供一种新的给药途径,这些新的或正在 研究中的疗法将给临床医师提供治疗偏头痛患者更广泛的选择手段。 相似文献
82.
S McShane L Glaser E R Greer J Houtz M F Tong M C Diamond 《Experimental neurology》1988,99(2):353-361
Previous studies on human cortical area 39 suggested that neuron:glial ratios differed between the sexes. These findings were the inspiration for the present investigation which dealt with neuronal and glial counts in area 39 in the male and female rat cerebral cortex. Transverse, celloidin or frozen sections, were cut from male and female brains (respectively) from 90-day-old Long-Evans rats. Neurons and glia were counted on enlarged photographs of stained sections, including area 39, with 35-mm Kodak Panatomic-X film using a Zeiss photomicroscope (X400). Five-by-three-inch prints were taped together in sequence to yield a 640X enlarged "montage" of area 39. Five cell types were differentiated with reference to a standard: neurons, astrocytes, oligodendrocytes, "dark astrocytes," and unidentified glia. The data were analyzed with a two-way analysis of variance (ANOVA: five cell types by two hemispheres). Student's t test and a paired t test were used when appropriate. The neuron:glial ratios in the male rats were consistently higher than those in the females in both hemispheres. The male right side had 12% (P less than 0.05) more neurons than the left; the female had 13% (P less than 0.05) more neurons on the left than the right. Similar, but not identical, asymmetrical patterns were seen with the glial cells. 相似文献
83.
84.
Contribution of redox-active iron and copper to oxidative damage in Alzheimer disease 总被引:1,自引:0,他引:1
Castellani RJ Honda K Zhu X Cash AD Nunomura A Perry G Smith MA 《Ageing research reviews》2004,3(3):319-326
Metal-catalyzed hydroxyl radicals are potent mediators of cellular injury, affecting every category of macromolecule, and are central to the oxidative injury hypothesis of Alzheimer disease (AD) pathogenesis. Studies on redox-competent copper and iron indicate that redox activity in AD resides exclusively within the neuronal cytosol and that chelation with deferoxamine, DTPA, or, more recently, iodochlorhydroxyquin, removes this activity. We have also found that while proteins that accumulate in AD possess metal-binding sites, metal-associated cellular redox activity is primarily dependent on metals associated with nucleic acid, specifically cytoplasmic RNA. These findings indicate aberrations in iron homeostasis that, we suspect, arise primarily from heme, since heme oxygenase-1, an enzyme that catalyzes the conversion of heme to iron and biliverdin, is increased in AD, and mitochondria, since mitochondria turnover, mitochondrial DNA, and cytochrome C oxidative activity are all increased in AD. These findings, as well as studies demonstrating a reduction in microtubule density in AD neurons, suggest that mitochondrial dysfunction, acting in concert with cytoskeletal pathology, serves to increase redox-active heavy metals and initiates a cascade of abnormal events culminating in AD pathology. 相似文献
85.
G M Clark Y C Tong J F Patrick P M Seligman P A Crosby J A Kuzma D K Money 《Journal of medical engineering & technology》1984,8(1):3-8
A multi-channel cochlear implant hearing prosthesis providing 22 separate channels of stimulation has been developed. The electronics for the implantable receiver-stimulator have been incorporated on a single chip, using digital circuits and employing CMOS technology. The chip is enclosed in a titanium capsule with platinum/ceramic electrode feed-throughs. A pocket-sized speech processor and directional microphone extract the following speech parameters: signal amplitude, fundamental frequency and formant frequency. The fundamental frequency is coded as electric pulse rate, and formant frequency by electrode position. The speech processor has been realized using hybrid circuits and CMOS gate arrays. The multi-channel prosthesis has undergone a clinical trial on four postlingually deaf patients with profound-total hearing losses. The speech perception results indicate that they were able to obtain open-set speech recognition scores for phonetically balanced words, CID sentences and spondees. In all cases the tests showed significant improvements when using the cochlear prosthesis combined with lipreading compared to lipreading alone. 相似文献
86.
Alan Ma Sunita Gurnasinghani Edwin P. Kirk Conor McClenaghan Gautam K. Singh Dorothy K. Grange Chetan Pandit Yung Zhu Tony Roscioli George Elakis Michael Buckley Bhavesh Mehta Philip Roberts Jonathan Mervis Andrew Biggin Colin G. Nichols 《American journal of medical genetics. Part A》2019,179(8):1585-1590
Cantú syndrome (CS), characterized by hypertrichosis, distinctive facial features, and complex cardiovascular abnormalities, is caused by pathogenic variants in ABCC9 and KCNJ8 genes. These genes encode gain‐of‐function mutations in the regulatory (SUR2) and pore‐forming (Kir6.1) subunits of KATP channels, respectively, suggesting that channel‐blocking sulfonylureas could be a viable therapy. Here we report a neonate with CS, carrying a heterozygous ABCC9 variant (c.3347G>A, p.Arg1116His), born prematurely at 32 weeks gestation. Initial echocardiogram revealed a large patent ductus arteriosus (PDA), and high pulmonary pressures with enlarged right ventricle. He initially received surfactant and continuous positive airway pressure ventilation and was invasively ventilated for 4 weeks, until PDA ligation. After surgery, he still had ongoing bilevel positive airway pressure (BiPAP) requirement, but was subsequently weaned to nocturnal BiPAP. He was treated for pulmonary hypertension with Sildenafil, but failed to make further clinical improvement. A therapeutic glibenclamide trial was commenced in week 11 (initial dose of 0.05 mg–1 kg–1 day–1 in two divided doses). After 1 week of treatment, he began to tolerate time off BiPAP when awake, and edema improved. Glibenclamide was well tolerated, and the dose was slowly increased to 0.15 mg?1 kg?1day?1 over the next 12 weeks. Mild transient hypoglycemia was observed, but there was no cardiovascular dysfunction. Confirmation of therapeutic benefit will require studies of more CS patients but, based on this limited experience, consideration should be given to glibenclamide as CS therapy, although problems associated with prematurity, and complications of hypoglycemia, might limit outcome in critically ill neonates with CS. 相似文献
87.
卵巢宫内膜样腺癌的病理组织学及组织化学分析 总被引:1,自引:0,他引:1
本文通过对24肺卵巢宫内膜样腺癌的巨检,镜及组织化学染色等结果分析,提出按该瘤所含组织成分,将其分为单纯型及混合型两大类。单纯型中分化程度不同又再分成Ⅰ,Ⅱ,ⅢⅣ级。混合型中根据所含成分又再分为腺棘癌,腺鳞癌,透明细胞腺癌型,含粘液腺癌型及含浆液腺癌型。讨论了该瘤的临床表现,发病率,组织来源,病理特征,诊断步骤及各类型与预后之间的关系。 相似文献
88.
人FascDNA的克隆及其在大肠杆菌中表达的研究 总被引:1,自引:1,他引:1
为获得高质量及充足的Fas蛋白,采用PCR技术调整Fas基因的开放阅读框架,使之与生物素化蛋白基因阅读框架一致;缺失了FascDNA基因的起始密码子并增加一个大肠杆菌偏性终止密码子,构建FascDNA和生物素化融合原核表达质粒PinPoint-Fas。将重组质粒转入大肠杆菌HB101,经500mmolIPTG在37℃条件下诱导4h,SDS-PAGE及Western印迹检测融合蛋白在大肠杆菌得以高效表达,表达量为细菌总蛋白的13.8%。用亲和层析树脂对生物素化融合蛋白进行亲和层析纯化,得到Fas重组的蛋白,且表达的Fas融合蛋白具有抗体结合活性。此蛋白的表达成功将解决Fas膜蛋白不易提取的难题,为深入研究Fas提供了良好材料来源 相似文献
89.
90.
利用光镜、电镜、免疫组化和形态学定量技术动态研究维生素A对大鼠四氯化碳肝纤维化的抑制作用。结果表明,维生素A可减少四氯化碳中毒大鼠肝内纤维连接蛋白和Ⅰ、Ⅲ型胶原沉积,抑制贮脂细胞向成纤维细胞转化,并可明显地减轻肝纤维化程度。本文还对维生素A抑制肝纤维化的机理及意义作了初步探讨。 相似文献