全文获取类型
收费全文 | 27769篇 |
免费 | 2282篇 |
国内免费 | 1285篇 |
专业分类
耳鼻咽喉 | 133篇 |
儿科学 | 561篇 |
妇产科学 | 656篇 |
基础医学 | 6013篇 |
口腔科学 | 565篇 |
临床医学 | 2259篇 |
内科学 | 4769篇 |
皮肤病学 | 326篇 |
神经病学 | 2153篇 |
特种医学 | 609篇 |
外国民族医学 | 6篇 |
外科学 | 1819篇 |
综合类 | 4202篇 |
现状与发展 | 6篇 |
预防医学 | 1945篇 |
眼科学 | 333篇 |
药学 | 2477篇 |
2篇 | |
中国医学 | 319篇 |
肿瘤学 | 2183篇 |
出版年
2024年 | 26篇 |
2023年 | 255篇 |
2022年 | 533篇 |
2021年 | 773篇 |
2020年 | 751篇 |
2019年 | 748篇 |
2018年 | 849篇 |
2017年 | 886篇 |
2016年 | 1021篇 |
2015年 | 1203篇 |
2014年 | 1776篇 |
2013年 | 2005篇 |
2012年 | 1911篇 |
2011年 | 2084篇 |
2010年 | 1775篇 |
2009年 | 1649篇 |
2008年 | 1700篇 |
2007年 | 1679篇 |
2006年 | 1581篇 |
2005年 | 1278篇 |
2004年 | 1132篇 |
2003年 | 876篇 |
2002年 | 727篇 |
2001年 | 628篇 |
2000年 | 484篇 |
1999年 | 424篇 |
1998年 | 316篇 |
1997年 | 321篇 |
1996年 | 217篇 |
1995年 | 206篇 |
1994年 | 205篇 |
1993年 | 142篇 |
1992年 | 136篇 |
1991年 | 153篇 |
1990年 | 118篇 |
1989年 | 110篇 |
1988年 | 89篇 |
1987年 | 85篇 |
1986年 | 73篇 |
1985年 | 64篇 |
1984年 | 48篇 |
1983年 | 28篇 |
1982年 | 39篇 |
1981年 | 44篇 |
1980年 | 26篇 |
1979年 | 40篇 |
1978年 | 19篇 |
1977年 | 21篇 |
1976年 | 28篇 |
1973年 | 10篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
41.
J. C. W. Mak H. C. M. Leung S. P. Ho F. W. S. Ko A. H. K. Cheung M. S. M. Ip M. M. W. Chan-Yeung 《Clinical and experimental allergy》2006,36(4):440-447
BACKGROUND: Reactive oxygen species may contribute to the pathogenesis of asthma. Functional genetic polymorphisms of antioxidant enzymes, superoxide dismutase (SOD) and catalase are good candidates for asthma susceptibility. OBJECTIVE: To investigate the association of the manganese-containing form of SOD (MnSOD) gene at amino acid position 16 (Val16Ala) and catalase gene in the promoter at A-21T and C-262T polymorphisms and asthma in a Hong Kong Chinese population. METHODS: The association study was conducted in a case-control design in asthma patients (n=251) and healthy controls (n=316) by genotyping. The functional significance was assessed by determining erythrocyte SOD and catalase activity. RESULTS: The Val allele of MnSOD at Val16Ala and the A allele of catalase gene at A-21T were not different between patients and controls, while the C allele of catalase gene at C-262T was found to be significantly different between patients and controls (P=0.033). The less frequent variant of catalase gene (-262T) was found to be protective from the development of asthma in a Hong Kong Chinese non-smoking population (adjusted odds ratio=0.35, 0.15-0.85; P=0.017). Asthma patients had elevated erythrocyte SOD and catalase activities in comparison with healthy controls (P<0.01). However, their activities were not associated with different genotypes within healthy controls or asthma patients. CONCLUSION: This is the first report showing that SOD and catalase functional activities are not associated with their respective genetic polymorphisms but related to the presence of asthma in a Hong Kong Chinese population. 相似文献
42.
TLR4 Asp299Gly、Thr399Ile基因多态性对变应性哮喘的发病及IgE水平的影响 总被引:3,自引:0,他引:3
目的 探讨TLR4 (toll likereceptor 4 )Asp2 99Gly、Thr399Ile基因多态性对变应性哮喘的发病和血浆IgE水平的影响。方法 利用聚合酶链反应 限制性片段长度多态性分析技术 (PCR RFLP) ,对 1 97例变应性哮喘患者和 1 5 6例健康人进行TLR4的Asp2 99Gly、Thr399Ile两位点的基因型检测。同时利用免疫发光法检测血浆IgE的水平。结果 1 97例变应性哮喘患者TLR4基因Asp2 99Gly位点Asp Asp、Asp Gly和Gly Gly的基因型频率为 0 .81 7、0 .1 4 7和 0 .0 36 ,与正常对照组相比差异无统计学意义 (χ2 =0 .0 32 ,P =0 .984 ) ;但变应性哮喘患者Gly Gly、Asp Gly基因型血浆总IgE对数值 ( x±s:2 .6 1 5± 0 .6 0 0 1 ,n =36 )与Asp Asp基因型血浆总IgE对数值 ( x±s:2 .2 4 0± 0 .6 894 ,n =1 6 1 )相比较高 ,差异有统计学意义 (P =0 .0 0 2 )。TLR4基因Thr399Ile位点Thr Thr、Thr Ile和Ile Ile的基因型频率为 0 .970、0 .0 2 0和 0 .0 1 0 ,与正常对照组相比差异无统计学意义 (χ2 =0 .6 2 0 ,P =0 .733) ;变应性哮喘患者Ile Ile、Thr Ile基因型血浆总IgE对数值 ( x±s:2 .4 1 7± 0 .4 4 2 3,n =6 )与Thr Thr基因型血浆总IgE对数值 ( x±s:2 .30 5± 0 .6 94 9,n =1 91 )相比差异无统计学意义 (P =0 .5 71 )。 相似文献
43.
粘病毒抵抗基因-1启动子88位点G/T多态性影响乙型肝炎病毒感染的自然转归 总被引:3,自引:1,他引:2
目的探讨乙型肝炎病毒(HBV)自限感染和慢性感染与粘病毒抵抗基因-1(MxA)启动子的-88位点G/T单核苷酸多态性的关系。方法收集100例抗-HBs和抗-HBc阳性的HBV自限感染者和340例慢性感染者的外周全血,提出基因组DNA;采用竞争分化聚合酶链反应技术为基础的方法进行MxA-88G/T基因分型;采用单因素Odds ratio和x^2检验等方法进行统计学分析。结果MxA-88G/G基因型(低表达型)检出率为50.2%(221/440),T/T基因型(高表达型)检出率为5.5%(24/440),G/T杂合型检出率为44.3%(195/440)。与慢性感染患者相比,自限感染患者携带较低的G/G基因型(41.0%与52.9%,P〈0.05)、G等位基因(62.5%与75.3%,P〈0.01)和较高的T/T基因型(16.0%与2.4%,P〈0.01)、T等位基因(37.5%与24.7%,P〈0.01),而两者之间的G/T杂合型差异无统计学意义。结论MxA-88G/T基因型能在一定程度上影响HBV感染的自然转归,有望成为临床上HBV感染转归的预测指标。 相似文献
44.
45.
46.
胃癌高系家族成员胃蛋白酶原C基因多态性及其诊断意义的探讨 总被引:1,自引:0,他引:1
采用限制性酶切片段长度多态性分析法,检测在胃癌高发区庄河检出的19例胃癌高系家族成员胃蛋白酶原C基因多态性,发现三种常见片段及一种稀有片段。对其中4例携带稀有片段的受检者进行了胃镜追踪观察,2.5年后发现1例早期胃癌。本文对此作了初步探讨。 相似文献
47.
H. Oka T. Yamamoto T. Kawazoe K. Saratani Y. Hikida 《Medical & biological engineering & computing》1988,26(3):260-266
A new impact response method using a fracture of a pencil-lead to produce an excitation pulse is proposed. Impact excitations
(rectangular pulse, triangular pulse and half-sine pulse) are strictly given in physical and mathematical definitions and
complete solutions to the impact excitations are provided for Noyes' model of the human tooth. When a relatively long triangular
pulse is applied to Noyes' model, which can express the physical characteristic of periodontal tissues, a sinusoidal damped
vibration of a single degree-of-freedom model is approximately obtained. The acceleration response is characterised by the
physical parameters (T, δ and Ao) and mechanical elements (m1, c1 and k) of which a single degree-of-freedom model is composed. By means of this method, the values of the parameters and elements
in the cases of healthy maxillary, healthy mandibular and pathological mandibular incisors are obtained. The single degree-of-freedom
model can express the high-frequency spectra of Noyes' model. The pathological tooth is characterised by a longer damped time
constant and a larger acceleration maximum. This impact response method can effectively be applied to clinical diagnosis in
view of the physical parameters and mechanical elements which have been derived. 相似文献
48.
MRI and SPECT findings in amyotrophic lateral sclerosis 总被引:1,自引:0,他引:1
Summary MRI was performed in 21 patients and single photon emission computed tomography (SPECT) withN-isopropyl-p-123I iodoamphetamine in 16 patients, to visualize upper motor neurone lesions in amyotrophic lateral sclerosis. T2-weighted MRI revealed high signal along the course of the pyramidal tract in the internal capsule and cerebral peduncle in 4 of 21 patients. SPECT images were normal in 4 patients, but uptake was reduced in the cerebral cortex that includes the motor area in 11. 相似文献
49.
L. Cheng †‡ T. Enomoto§ T. Hirota† M. Shimizu † N. Takahashi† M. Akahoshi† A. Matsuda† Y. Dake§ S. Doi¶ K. Enomoto A. Yamasaki S. Fukuda X.-Q. Mao J. M. Hopkin M. Tamari† T. Shirakawa † 《Clinical and experimental allergy》2004,34(8):1192-1201
BACKGROUND: A recent report provided evidence that a disintegrin and metalloprotease domain 33 (ADAM33), a member of the ADAM family, is a novel susceptibility gene in asthma linked to bronchial hyper-responsiveness. However, there has been no investigation of the genetic role of ADAM33 variants in nasal allergy. OBJECTIVE: The purpose of this study was to test the association between ADAM33 polymorphisms and Japanese cedar pollinosis (JCPsis), a most common seasonal allergic rhinitis in Japan. METHODS: We conducted a case-control association study among a Japanese population, involving 95 adult individuals with JCPsis and 95 normal healthy controls. A total of 22 single-nucleotide polymorphisms (SNPs) in ADAM33 were genotyped using PCR-based molecular methods. RESULTS: Six SNPs of ADAM33 gene, three in introns (7575G/A, 9073G/A and 12540C/T) and three in the coding region (10918G/C, 12433T/C and 12462C/T), were strongly associated with JCPsis (P = 0.0002-0.022 for absolute allele frequencies) and most of the SNPs were in linkage disequilibrium with each other. A higher frequency of the common alleles of these SNPs was noted for the subjects with JCPsis in comparison with healthy controls. We also identified a haplotype associated with the disease susceptibility. In addition, associations were found between ADAM33 polymorphisms and various cedar pollinosis phenotypes including clinical severity, eosinophil counts in nasal secretion and allergen-specific IgE levels in sera, but not total serum IgE levels. CONCLUSION: These results indicate that polymorphisms in the ADAM33 gene are associated with susceptibility to allergic rhinitis due to Japanese cedar pollen, but the functional relationship still needs clarification. 相似文献
50.
T. Iwanaga †‡ A. McEuen† A. F. Walls† J. B. Clough† T. P. Keith§ S. Rorke† S. J. Barton† S. T. Holgate† J. W. Holloway † 《Clinical and experimental allergy》2004,34(7):1037-1042
BACKGROUND: Mast cell chymase has the potential to be an important mediator of inflammation and remodelling in the asthmatic lung. Previous studies have examined association between promoter polymorphism of the chymase gene (CMA1) and allergic phenotypes but the significance of this polymorphism is unclear. We have examined association of a CMA1 variant in relation to asthma in a large UK Caucasian family cohort. METHODS: A polymorphism of the CMA1 gene promoter (-1903G/A) was genotyped in 341 asthmatic families and in 184 non-asthmatic adults recruited from the UK PCR-RFLP based genotyping. Association with asthma diagnosis, atopy, specific and total IgE, and atopy and asthma severity was examined. RESULTS: Case-control studies did not reveal a significant difference in allele frequency between asthmatics and controls. A significant association was found between CMA1 genotypes and total IgE levels in subjects with self-reported eczema that remained significant after correction for multiple testing (median total serum IgE GG 297 kU/L, GA 144 kU/L, AA 48.4 kU/L, Pc=0.0032). CONCLUSION: These data suggest that CMA1 promoter polymorphism does not contribute to asthma susceptibility or severity but may be involved in regulating IgE levels in patients with eczema. 相似文献