全文获取类型
收费全文 | 53439篇 |
免费 | 4208篇 |
国内免费 | 2401篇 |
专业分类
耳鼻咽喉 | 326篇 |
儿科学 | 820篇 |
妇产科学 | 1286篇 |
基础医学 | 12213篇 |
口腔科学 | 936篇 |
临床医学 | 3866篇 |
内科学 | 8543篇 |
皮肤病学 | 776篇 |
神经病学 | 2520篇 |
特种医学 | 1675篇 |
外国民族医学 | 9篇 |
外科学 | 2553篇 |
综合类 | 7539篇 |
现状与发展 | 11篇 |
预防医学 | 3656篇 |
眼科学 | 503篇 |
药学 | 5079篇 |
4篇 | |
中国医学 | 964篇 |
肿瘤学 | 6769篇 |
出版年
2024年 | 43篇 |
2023年 | 523篇 |
2022年 | 770篇 |
2021年 | 1457篇 |
2020年 | 1384篇 |
2019年 | 1331篇 |
2018年 | 1341篇 |
2017年 | 1561篇 |
2016年 | 1789篇 |
2015年 | 2119篇 |
2014年 | 2923篇 |
2013年 | 3704篇 |
2012年 | 2905篇 |
2011年 | 3381篇 |
2010年 | 2827篇 |
2009年 | 2884篇 |
2008年 | 2981篇 |
2007年 | 3016篇 |
2006年 | 2951篇 |
2005年 | 2585篇 |
2004年 | 2391篇 |
2003年 | 2001篇 |
2002年 | 1726篇 |
2001年 | 1565篇 |
2000年 | 1302篇 |
1999年 | 1067篇 |
1998年 | 954篇 |
1997年 | 851篇 |
1996年 | 750篇 |
1995年 | 702篇 |
1994年 | 692篇 |
1993年 | 472篇 |
1992年 | 486篇 |
1991年 | 393篇 |
1990年 | 346篇 |
1989年 | 295篇 |
1988年 | 248篇 |
1987年 | 159篇 |
1986年 | 177篇 |
1985年 | 219篇 |
1984年 | 173篇 |
1983年 | 69篇 |
1982年 | 93篇 |
1981年 | 97篇 |
1980年 | 93篇 |
1979年 | 76篇 |
1978年 | 61篇 |
1977年 | 34篇 |
1976年 | 40篇 |
1975年 | 9篇 |
排序方式: 共有10000条查询结果,搜索用时 218 毫秒
51.
G. V. Petrova V. A. Adarichev A. A. Krivenko G. S. Dymshits A. L. Markel' G. S. Yakobson 《Bulletin of experimental biology and medicine》1997,124(2):773-775
Sensitivity of normotensive Wistar rats and NISAG rats (with hereditary arterial hypertension) to heat stress is compared
at the organism and cell levels. High temperature sensitivity of NISAG rats correlates with a low content of the main heat
shock protein HSP70. This relationship can serve as a biochemical marker of predisposition to arterial hypertension.
Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 124, No. 8, pp. 171–173, August, 1997 相似文献
52.
Xu Dai-gen He Han-zhen Zhang Guo-gao B. Gansewendt H. Peter H. M. Bolt 《华中科技大学学报(医学英德文版)》1993,13(2):100-104
Monohalogenated methanes (methyl chloride, methyl bromide and methyl iodide) are mutagenic and carcinogenic. The possible mechanism of these effects, DNA methylation, was studied. DNA adducts from orgnas of F344 rats exposed to these chemicals were separated and identified with high performance liquid chromatography (HPLC) and gaschro-matography/massspectrometry (GC/ MS). DNA adducts, 7-methylguanine (7-MeG) and O6-Methylguanine(08-MeG), incorporation of14C into de novo synthesis of nucleobases could be observed in enzymatic DNA hydrolysates by HPLC and determination of the radioactivity in the fractions. The formation of DNA add,ue,ts in the studied organs was only quantitatively different. The formation of O6-MeG was further pioved by analysing the acidic hydrolysates using HPLC with non-radioactive O6MeG as internal standard. 7-MeG and 3-MeA were identified with GC/MS analysis. 相似文献
53.
中国汉坦病毒H82O5株G2糖蛋白基因的克隆及在真核细胞中的瞬时表达 总被引:2,自引:1,他引:1
从感染病毒乳鼠脑组织提取总RNA,采用RT-PCR和分子克隆技术将扩增到的G2糖蛋白基因插入含CMV启动子的pcDNA3.1/His质粒载体中,通过脂质体介导转染COS-7细胞,用SDS-PAGE、Western-blot及IFIA方法分别测定表达产物的相对分子量及特异性。结果证明获得正向插入的G2-pcDNA3.1/His重组表达质粒,表达产物的相对分子量为56ku,与理论预期大小一致,并且可与汉坦病毒H8205株的腹水抗体起特异反应。表明构建的G2-pcDNA3.1/His重组质粒所表达的蛋白为中国汉坦病毒株特有,能在哺乳动物细胞中表达并具有抗原性,重组质粒可应用于汉坦病毒的DNA疫苗研究。 相似文献
54.
采用淋巴细胞分离液分离外周血中的有核细胞,经细胞裂解液处理,上清提取RNA,沉淀提取DNA,用分离液分离所得红细胞沉淀制备血红蛋白溶液。经对抽提物质量进行评价,发现3种提取物质量均高。本法能从少量外周血中同时分离DNA、RNA及血红蛋白,高效易操作,值得推广。 相似文献
55.
目的探讨p16基因突变在白血病发生中的作用及基因突变的机制。方法利用点突变检测仪、水平和垂直板电泳对p16基因的外显子1、外显子2的PCR扩增产物作缺失和点突变分析。结果在白血病35例临床标本中有22例发生缺失突变,6例发生点突变,突变率约80%。在22例缺失突变病例中,有10例为不完全缺失突变即有低于外显子509bp的扩增产物。结论p16基因含有“GC”DNA重复顺序,易发生DNA重组及易位和重排。在白血病发生中起重要作用 相似文献
56.
肿瘤坏死因子β基因多态性在中国汉族SLE病人中的分布特点及与不同人种的比较研究 总被引:2,自引:0,他引:2
目的 :探讨中国江苏地区汉族人群TNFβ基因多态性在SLE病人中分布特点 ,并与不同人种进行比较研究。 方法 :收集江苏地区 16 8名无血缘关系健康个体及 6 6例SLE病人的静脉血提取DNA ,应用聚合酶链反应限制性片段长度多态性(PCR RFLP) ,分析TNFβ基因的多态性。 结果 :中国汉族SLE病人与白种SLE病人TNFβ基因频率差异无统计学意义 ;中国汉族健康个体TNFβ 1等位基因频率明显高于白种健康个体 ;SLE病人TNFβ 2基因频率较正常人明显升高 (SLE病人 6 7 4% ,正常人 5 5 1% ,P <0 0 5 ,R =1 6 8) ;中国汉族SLE病人与白种SLE病人TNFβ基因频率差异无统计学意义。 结论 :TNFβ等位基因频率在正常人分布具有种族差异 ,但在SLE病人分布无种族差异。 相似文献
57.
D J Bowen 《Journal of clinical pathology》2002,55(1):1-18
This review focuses on selected areas that should interest both the scientist and the clinician alike: polymorphisms within the factor VIII and factor IX genes, their linkage, and their ethnic variation; a general assessment of mutations within both genes and a detailed inspection of the molecular pathology of certain mutations to illustrate the diverse cause–effect relations that exist; a summary of current knowledge on molecular aspects of inhibitor production; and an introduction to the new areas of factor VIII and factor IX catabolism. An appendix defining various terms encountered in the molecular genetics of the haemophilias is included, together with an appendix providing accession numbers and locus identification links for accessing gene and sequence information in the international nucleic acid databases. 相似文献
58.
BACKGROUND: The responses of mice to the mite allergen Der p 1 have been used to study the mechanisms of allergic sensitization and the development of new types of immunotherapy. Many of the studies require a knowledge of the T cell epitopes, and because Der p 1 is polymorphic, the effect of natural amino acid substitution in the allergen. The intranasal administration of peptides containing T cell epitopes can induce a mucosal tolerance but it is not known if the major activity is limited to stimulatory peptides and if, as found for autoimmunity, some epitopes are not inhibitory. OBJECTIVE: To determine and compare the sequences of Der p 1 which contain stimulatory epitopes for the high responding H-2(b) and H-2(q) mice and the sequences which induce tolerance by intranasal administration of peptides. METHODS: T cell responses of mice immunized with Der p 1 were measured by in vitro T cell stimulation assays so an extensive study of epitope recognition and intranasal tolerance could be made. Synthetic peptides were used to examine the stimulatory and inhibitory ability of all Der p 1 sequences and to map the major H-2(b) epitope in detail. This included the effect of the common polymorphic amino acid 124 substitution found within this epitope. RESULTS: Three and two regions, respectively, were found to contain stimulatory T cell epitopes for H-2(b) and H-2(q) mice. The peptides in these regions were also the most active at inducing intranasal tolerance for the responding haplotype. The correspondence between inhibitory and stimulatory peptides was maintained for the fine mapping of the major H-2(b) epitope. This was found about a core region of 118-126 which was overlapping but separate to a consensus sequence for the binding of endogeneous peptides. Peptides with alanine at the naturally polymorphic residue 124 stimulated and inhibited responses to Der p 1 more effectively, while peptides with the valine 124 variant were immunogenic but poorly cross-reactive. CONCLUSIONS: The intranasal administration of peptides representing each of five epitopes recognized by two strains of mice were able to induce mucosal tolerance and the major tolerizing activity was limited to these epitopes. The position of the core major epitope for C57 mice, which differs from a previously predicted epitope, and its specificity for the natural alanine 124 variant is described. 相似文献
59.
目的应用基因芯片研究三氧化二砷(As2O3)处理前后K562细胞基因表达的变化.方法提取As2O3处理前后K562细胞的总RNA,纯化为mRNA后再反转录为cDNA.cDNA经限制性内切酶Sau3AI切割后,cDNA片段分别用Cy3和Cy5标记,与自制的包含348个基因片段的胎盘库芯片杂交.结果杂交结果经扫描和软件分析,发现了11个差异表达的基因片段,其中有3个基因片段与细胞凋亡密切相关.结论我们构建的胎盘库基因芯片可以成功地用于研究药物作用前后基因表达的变化. 相似文献
60.
CpG DNA预防小鼠哮喘模型的形成 总被引:9,自引:1,他引:8
目的 研究含胞嘧啶鸟嘌呤核苷酸的免疫刺激元件 (CpGDNA)能否预防卵蛋白致敏小鼠哮喘模型的形成。方法 将 18只BALB/c小鼠均分为 3组 ,其中卵蛋白致敏哮喘组 (OVA组 )和CpG预防组 (CpG组 )皮下注射卵蛋白致敏制作哮喘模型 ,然后用卵蛋白激发 2次 ;阴性对照组 (NS组 )皮下注射生理盐水 ,然后生理盐水激发 2次。CpG组在致敏前腹腔注射CpGDNA 10 0 μg/ 10 0 μL ,其他两组不作干预。 3组分别在第 2次激发后 2 4h测外周血OVA特异性IgE、IgG1、IgG2a,并处死小鼠测肺泡灌洗液 (BALF)中的细胞总数及嗜酸性粒细胞 (EOS)计数 ,肺组织病理切片观察形态学改变 ,并测定脾细胞培养上清液中OVA特异性IFN γ。结果 CpG组BALF中细胞总数和嗜酸性粒细胞明显低于OVA组 ,P <0 .0 5 ;CpG组肺组织炎症反应较OVA组明显减轻 ;CpG组脾细胞培养上清液中OVA特异性IFN γ的浓度明显高于OVA组 ,P <0 .0 5 ;CpG组外周血OVA特异性IgE和IgG1均低于OVA组 ,P <0 .0 5 ;CpG组IgG2a较OVA组为高 ,P <0 .0 5。结论 CpGDNA能预防卵蛋白致敏小鼠哮喘模型的形成 相似文献