全文获取类型
收费全文 | 60502篇 |
免费 | 4388篇 |
国内免费 | 2137篇 |
专业分类
耳鼻咽喉 | 382篇 |
儿科学 | 1409篇 |
妇产科学 | 740篇 |
基础医学 | 9010篇 |
口腔科学 | 792篇 |
临床医学 | 4606篇 |
内科学 | 9429篇 |
皮肤病学 | 1160篇 |
神经病学 | 4806篇 |
特种医学 | 861篇 |
外国民族医学 | 11篇 |
外科学 | 4442篇 |
综合类 | 6405篇 |
现状与发展 | 10篇 |
预防医学 | 4920篇 |
眼科学 | 997篇 |
药学 | 10345篇 |
8篇 | |
中国医学 | 3069篇 |
肿瘤学 | 3625篇 |
出版年
2023年 | 875篇 |
2022年 | 1498篇 |
2021年 | 1915篇 |
2020年 | 1809篇 |
2019年 | 2394篇 |
2018年 | 2348篇 |
2017年 | 1977篇 |
2016年 | 1900篇 |
2015年 | 2100篇 |
2014年 | 3279篇 |
2013年 | 4016篇 |
2012年 | 3405篇 |
2011年 | 4057篇 |
2010年 | 3383篇 |
2009年 | 2797篇 |
2008年 | 2648篇 |
2007年 | 2482篇 |
2006年 | 2107篇 |
2005年 | 1839篇 |
2004年 | 1638篇 |
2003年 | 1513篇 |
2002年 | 1244篇 |
2001年 | 1091篇 |
2000年 | 835篇 |
1999年 | 849篇 |
1998年 | 698篇 |
1997年 | 649篇 |
1996年 | 556篇 |
1995年 | 489篇 |
1994年 | 437篇 |
1993年 | 409篇 |
1992年 | 371篇 |
1991年 | 348篇 |
1990年 | 307篇 |
1989年 | 247篇 |
1988年 | 244篇 |
1986年 | 185篇 |
1985年 | 806篇 |
1984年 | 1036篇 |
1983年 | 821篇 |
1982年 | 944篇 |
1981年 | 888篇 |
1980年 | 662篇 |
1979年 | 619篇 |
1978年 | 444篇 |
1977年 | 356篇 |
1976年 | 408篇 |
1975年 | 311篇 |
1974年 | 193篇 |
1973年 | 196篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
本文采用俯卧拍背法缓解胆绞痛41例,其中23例经此法治疗后疼痛立即消失(56.1%);15例明显缓解(36.6%);3例缓解不明显(7.3%)。具有操作简便、安全,易被患者接受,值得推广。 相似文献
52.
Prevention of nutritional deficiencies should be attained by the consumption of a good diet. Unfortunately, in the case of iron, this is not always possible, and it is advantageous to fortify food with iron. Milk-based formulas and cereals are the most commonly used iron-fortified products in infancy and early childhood. Bioavailability of iron from cereals is low and more clinical studies on the field are necessary to demonstrate the effectiveness of iron-fortified cereals in infants and children of developing countries. Infections and excessive blood loss in infancy related to the use of fresh, pasteurized or powdered cow milk result in much of the anemia we currently see in industrialized countries. Vitamin A deficiency interacts with iron metabolism and recent intervention studies have shown that anemia in Vitamin A deficient children can be successfully treated with oral supplements. 相似文献
53.
F. D. Knollmann J. C. Bck S. Teltenktter W. Wlodarczyk A. Mühler Th. J. Vogl R. Felix 《Journal of magnetic resonance imaging : JMRI》1997,7(1):191-196
The purpose of our research was to determine the effects of superparamagnetic iron oxide on MR imaging of the portal venous system. Eight piglets were examined in deep anaesthesia and respiratory arrest using a time-of-flight magnetic resonance fast low angle shot, two-dimensional angiography sequence at 1.5T. MR angiograms were acquired precontrast and after intravenous administration of a cumulative dose of 10, 20 and 40 μmol/kg SHU 555A, a superparamagnetic iron oxide contrast agent for MR imaging with a particle size of 60 nm. For each dose, two subsequent sets of scans were obtained and reconstructed by a maximum-intensity-projection algorithm. Hepatic parenchymal and portal venous signal intensities were measured, and portal vein contrast calculated for each set of scans. All examinations were visually rated as to portal vein contrast and homogeneity by two blinded observers. Receiver operating characteristics of both observers were analyzed. The contrast agent reduced hepatic parenchymal signal in a dose-dependent way. After a cumulative dose of 10 μmol iron oxide, hepatic parenchymal signal intensity decreased to 63 ± 6% (average of measurements at 4 and 14 minutes, mean ± standard error of the mean), after 20 μmol to 24 ± 3%, and after 40 μmol to 12 ± 1% of control. Intra-vascular signal in the left main portal vein branch increased to 117 ± 6%, 127 ± 10%, and 133 ± 9% of control, respectively. The contrast-to-noise ratio of the portal vein improved (521 ± 90%, 891 ± 178%, and 995 ± 201% of control in the left portal vein main branch). Intravascular signal intensities increased slightly. The combined effect improved contrast of the portal vein stem and its branches. Receiver operating characteristics analysis documented dose-dependency of contrast medium effects on portal venous contrast and intravascular homogeneity. Visual rating also indicated a positive effect on portal venous contrast. The superparamagnetic iron oxide agent improved portal venous contrast with surrounding hepatic parenchyma in this normal animal model, and could potentially result in more accurate diagnosis of portal venous pathology. 相似文献
54.
L.A. BROWN M. WISELKA A. CAMPBELL J.H. PRINGLE K. NICHOLSON I. LAUDER 《Histopathology》1991,19(3):225-230
A 47-year-old man with persistent severe oropharyngeal ulceration developed a high-grade T-cell lymphoma soon after commencing treatment with cyclosporin A. Using Southern blotting to identify T-cell beta-chain gene rearrangements, evidence of clonal restriction was found both in blood and lymph node DNA samples. Two BamH1 rearranged bands were demonstrated in both samples. In the blood a 16 Kb band predominated, with a weaker 28 kb band. In the lymph node sample this pattern was reversed. The findings suggest that a bi-clonal population of T-lymphocytes or clonal evolution of an existing T-cell monoclone had developed, and that cyclosporin contributed to the emergence of a high-grade T-cell lymphoma. 相似文献
55.
Adultacuteleukemia (AL)isoneofthemostcommonmalignanttumorsofhematology .Withtherecentprogressinchemotherapyandsupportivether apy ,theremissionandsurvivalrateinALhavebeenmarkedlyimproved .However ,drugresistanceandrelapsearestillimportantfactorsaffectinglongsur vivalofthese patients .Theabnormalregulationofcellcycleisanotherfactorthatcannotbeignoredex ceptformultipledrugresistance (MDR) .WedetectcyclinA ,multidrugresistantgene (mdrl) ,topoiso meraseⅡα(TopⅡα)andbcl 2inadultpatientswithA… 相似文献
56.
57.
利用气相色谱—质谱—计算机联用仪分析了云南省腾冲县产珠子参挥发油的成份,从中鉴定了27种化合物,测定了它们的相对含量,其中有10种倍半萜烯和一种倍半萜醇。 相似文献
58.
59.
北京、广州、上海城市居民营养知识、态度、行为的调查 总被引:27,自引:1,他引:26
对北京、广州和上海三大城市随机抽取的965名年龄在20~50岁的城市居民进行有关营养知识、态度和行为(K-A-P)的调查。结果显示,三地区调查对象的营养知识水平不高。营养知识的得分与其自身受教育程度有相关性(r=0.3011,P<0.01)。年龄在35岁以上的对象,营养知识的得分高于年轻人;三地区调查对象对营养知识的获取,合理的膳食模式,卫生的饮食习惯均持有积极、肯定的态度。食物消费频度调查结果表明,米/面、肉/禽、蔬菜、水果、奶及奶制品的消费量较高。此外,89.5%,78.8%和47.8%的调查对象分别选择报纸、电视、广播作为其主要营养信息来源。本次调查为将来的营养宣教的内容和方法提供依据。 相似文献
60.
移植肾组织TGF-β1和MMP-2表达及IV型胶原沉积与慢性移植肾肾病的关系 总被引:1,自引:0,他引:1
目的 探讨移植肾组织中转化生长因子β1(TGF-β1)和基质金属蛋白酶2(MMP-2)的表达及IV型胶原沉积与慢性移植肾肾病(CAN)的关系.方法 对18例CAN患者进行了移植肾切除术.光镜下观察切除的肾组织标本并根据其纤维化的程度进行分期,用免疫组织化学技术和图像分析法检测移植肾组织中TGF-β1和MMP-2表达量及IV型胶原沉积情况,并分析患者血肌酐(Cr)和尿素氮(BUN)的水平与移植肾纤维化程度的关系.结果 随着患者移植肾纤维化程度的加重,血清肌酐、尿素氮及肾组织中TGF-β1、IV型胶原基因表达量均增加,MMP-2表达量于移植肾纤维化早期明显升高,并随移植肾纤维化程度加重而逐渐降低.结论 移植肾组织中TGF-β1表达量增高及IV型胶原沉积可以促进CAN的进程,而MMP-2则可抑制其进展. 相似文献