全文获取类型
收费全文 | 2773篇 |
免费 | 216篇 |
国内免费 | 154篇 |
专业分类
耳鼻咽喉 | 22篇 |
儿科学 | 22篇 |
妇产科学 | 31篇 |
基础医学 | 607篇 |
口腔科学 | 31篇 |
临床医学 | 131篇 |
内科学 | 539篇 |
皮肤病学 | 31篇 |
神经病学 | 198篇 |
特种医学 | 39篇 |
外科学 | 192篇 |
综合类 | 560篇 |
预防医学 | 118篇 |
眼科学 | 13篇 |
药学 | 255篇 |
中国医学 | 79篇 |
肿瘤学 | 275篇 |
出版年
2024年 | 1篇 |
2023年 | 17篇 |
2022年 | 33篇 |
2021年 | 73篇 |
2020年 | 83篇 |
2019年 | 61篇 |
2018年 | 48篇 |
2017年 | 58篇 |
2016年 | 89篇 |
2015年 | 95篇 |
2014年 | 158篇 |
2013年 | 164篇 |
2012年 | 172篇 |
2011年 | 159篇 |
2010年 | 154篇 |
2009年 | 142篇 |
2008年 | 145篇 |
2007年 | 204篇 |
2006年 | 187篇 |
2005年 | 175篇 |
2004年 | 160篇 |
2003年 | 160篇 |
2002年 | 113篇 |
2001年 | 94篇 |
2000年 | 95篇 |
1999年 | 88篇 |
1998年 | 46篇 |
1997年 | 36篇 |
1996年 | 36篇 |
1995年 | 31篇 |
1994年 | 18篇 |
1993年 | 5篇 |
1992年 | 9篇 |
1991年 | 2篇 |
1990年 | 9篇 |
1989年 | 4篇 |
1988年 | 5篇 |
1987年 | 2篇 |
1986年 | 1篇 |
1985年 | 4篇 |
1984年 | 4篇 |
1981年 | 1篇 |
1977年 | 1篇 |
1974年 | 1篇 |
排序方式: 共有3143条查询结果,搜索用时 15 毫秒
41.
目的 探讨细胞黏附分子CD99在人髓母细胞瘤组织中的表达特点及其临床意义。方法 采用免疫组化法检测107例髓母细胞瘤及15例瘤旁正常脑组织标本中CD99的表达。所有病人均随访至死亡或截止至2013年12月,随访时间为12~80个月,利用Kaplan-Meier生存曲线进行生存分析。结果 髓母细胞瘤CD99阳性表达率(57.94%,62/107)明显高于瘤周正常脑组织(0%,0/15;P<0.05)。CD99的表达水平与病人性别、年龄、肿瘤的病理组织学分型和分子亚型均无明显相关性(P>0.05)。CD99的高表达与髓母细胞瘤病人的预后呈显著负相关(P<0.05)。结论 CD99高表达与髓母细胞瘤预后显著相关,可作为预后判断的指标及治疗髓母细胞瘤潜在的新靶点。 相似文献
42.
43.
Gene Expression Ominibus (GEO)是供学者们分享基因表达谱芯片数据、高通量测序数据等的国际化的公共资源平台,其中涵盖了应用炎癌模型获得的大量相关实验数据,比如关于某些炎性因子的表达情况.这些数据为炎癌转化中的调控网络和分子机制的研究提供了帮助,也为肿瘤的防治提供了新思路.研究者针对新的预测基因进行研究时,起源于各种疾病模型或实验处理的GEO数据库为寻找其有关功能提供了有利条件和有力证据. 相似文献
44.
Marta Martínez-Gil José Miguel Quesada María Isabel Ramos-González María Isabel Soriano Ricardo E. de Cristóbal Manuel Espinosa-Urgel 《Research in microbiology》2013,164(5):382-389
The extracellular matrix of bacterial biofilms has at least two key functions: to serve as a structural scaffold for the multicellular community, and to play a protective role against external stress. In this work, we report a compensatory effect whereby Pseudomonas putida reacts to the lack of either of the two main surface proteins involved in biofilm formation, LapA and LapF, by increasing expression and production of a species-specific EPS. Elevated levels of the second messenger molecule cyclic di-GMP alter the balance of extracellular matrix components, and the phenotypes of lapA and lapF mutants under these conditions are indicative of direct interactions taking place between large secreted proteins and exopolysaccharides. Our data suggest the existence of a mechanism by which bacteria would sense alterations in the composition of the extracellular matrix, leading to changes in expression of the different elements. 相似文献
45.
《Connective tissue research》2013,54(1):63-75
Little is known about patterns of gene expression from cells populating the connective tissues. This study investigated the possible variance of gene expression profile between human osteoblasts (HO) and human fibroblasts (HF) in vitro, using DNA microarray technology. Clustering identification was used to compare expression patterns between HO and HF for biological significance. Our results showed that genes encoding the extracellular matrix or apoptosis-related proteins tended to be expressed in greater abundance in HO, while more proteolysis-related proteins were expressed in higher level in HF. Significant differences in expression were also noted with genes related to signaling pathways. To confirm the array results, three genes (periostin, MFG-E8, MMP-10) were selected and analyzed independently by RT-PCR and northern blot. The results were found consistent with the array data in HO and HF. The present findings suggest that HO and HF differ not only phenotypically but in the expression level of tissue specific genes to assure the turnover and homeostasis of their respective tissues. 相似文献
46.
Paul R. Odgren Carole A. MacKay April Mason-Savas Meiheng Yang Geneviève Mailhot Mark J. Birnbaum 《Connective tissue research》2013,54(4):229-234
Escherichia coli β-galactosidase (β-gal), encoded by the lacZ gene, has become an essential tool in studies of gene expression and function in higher eukaryotes. lac-Z is widely used as a marker gene to detect expression of transgenes or Cre recombinase driven by tissue-specific promoters. The timing and location of promoter activity is easily visualized in whole embryos or specific tissues using the cleavable, chromogenic substrate, 5-bromo-4-chloro-3-indolyl-D-galactopyranoside (X-gal). The tissue specificity of promoters in transgenic constructs is routinely tested by using a promoter of choice to drive lacZ. Alternatively, the targeted expression of Cre recombinase to perform in vivo recombination of loxP sites can be visualized by β-gal staining in mice carrying a Cre-activated lacZ transgene, such as the ROSA26 strain. In the course of our investigations, we examined β-gal activity in bone tissue from genetically normal mice using standard detection methodology and found very high endogenous activity in bone-resorbing osteoclasts. This was true in frozen, paraffin, and glycol methacrylate sections. X-gal staining colocalized with the osteoclast marker, tartrate-resistant acid phosphatase (TRAP). β-gal activity was present in osteoclasts in long bones, in the mandible, and in both neonatal and more mature animals. We present this brief article as a caution to those testing genetic models of skeletal gene expression using β-gal as a marker gene. 相似文献
47.
48.
目的研究KISS—1、VEGF—C在乳头状甲状腺癌组织中的表达情况,分析两者表达与乳头状甲状腺癌临床病理特征的关系以及两者的相关性。方法收集乳头状甲状腺癌组织病理标本48例及其正常甲状腺组织20例,采用免疫组织化学SP法检测KISS—1、VEGF—C在乳头状甲状腺癌组织中的表达情况,分析KISS—1、VEGF—C在乳头状甲状腺癌组织中阳性表达率与临床病理学特征之间的关系以及两者表达之间的相关性。结果KISS-1、VEGF—C在乳头状甲状腺癌组织和正常甲状腺组织中的阳性表达率之间具有显著性差异(P〈0.01)。KISS-1、VEGF—C在乳头状甲状腺癌组织中的阳性表达率与肿瘤大小、颈部淋巴结转移、临床分期相关且均有显著性差异(P〈0.05)。KISS-1和VEGF—C的表达与患者的性别、年龄均无关(P〉0.05);KISS-1与VEGF—C在乳头状甲状腺癌组织表达存在负相关关系(P〈0.05)。结论KISS—1、VEGF—C的表达水平与乳头状甲状腺癌有关,且与肿瘤大小、颈部淋巴结转移状况、临床分期相关,与患者性别、年龄无关。KISS-1在乳头状甲状腺癌组织的表达与VEGF—C呈负相关关系。KISS-1、VEGF—C联合检测可作为乳头状甲状腺癌恶性潜能的判断指标。 相似文献
49.
50.
《Immunobiology》2017,222(3):571-581
IntroductionFexofenadine (FXF) is a third-generation antihistamine drug and osthole is assumed as a natural antihistamine alternative. This paper compares results of histamine, FXF and osthole impact on HRH-1, COX-2, NF-κB-p50, CCR1 mRNA expression. We also measured mRNA expression of IL-1β and CCL5/RANTES in incubated peripheral blood mononuclear cells (PBMC) to compared how histamine, FXF and osthole had influence on expression level and interacts on product secretion.ObjectiveThe purpose was to investigate expression pattern in asthma PBMC.MethodsThe cultures were treated 72 h with FXF and osthole. We measured mRNA expression of histamine HRH-1, COX-2, NF-κB-p50, CCR1, IL-1β and CCL5/RANTES with Real-Time PCR (RT-PCR).ResultsThe present study suggest that osthole may be a potential inhibitor of histamine H1 receptor activity. We also demonstrated that cells cultured with histamine increase COX-2 mRNA expression and osthole reduce it.ConclusionAllergy remains one of the most common chronic diseases in Europe and it is rapidly approaching epidemic proportions; with current predictions estimating that the number of allergy-afflicted will equal the healthy population by 2020. It is therefore paramount to find new pharmaceuticals which successfully combat allergic disease. 相似文献