首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   199篇
  免费   35篇
  2024年   1篇
  2023年   9篇
  2022年   13篇
  2021年   33篇
  2020年   20篇
  2019年   24篇
  2018年   17篇
  2017年   5篇
  2016年   12篇
  2015年   11篇
  2014年   39篇
  2013年   10篇
  2012年   10篇
  2011年   8篇
  2010年   5篇
  2009年   4篇
  2005年   1篇
  2004年   2篇
  2002年   1篇
  1998年   1篇
  1995年   1篇
  1993年   1篇
  1987年   1篇
  1983年   2篇
  1982年   1篇
  1981年   1篇
  1976年   1篇
排序方式: 共有234条查询结果,搜索用时 15 毫秒
101.
This study was aimed to explore the effects of miR-29a-5p expression and its target gene TPX2 (target protein for Xenopus kinesin-like protein 2) on endometrial cancer (EC) devel on EC development and to assess the prognostic impacts of TPX2. Microarray-based GEO and TCGA (the Cancer Genome Atlas) EC expression data were used to identify differentially expressed miRNAs and mRNAs. The observed potential target relationship between miR-29a-5p and TPX2 was verified using TargetScan and luciferase reporter assays. The mRNA and protein expression levels of miR-29a-5p and TPX2 were confirmed by qRT-PCR and western blot, respectively. Associations between TPX2 expression and patient prognosis were assessed using Kaplan-Meier and log-rank assays. Changes in EC-derived cell proliferation, invasion and apoptosis after exogenous miR-29a-5p and TPX2 over-expression and/or silencing were assessed using CCK-8 (cell counting kit-8), colony formation, Transwell and flow cytometry assays, respectively. We found that in primary EC tissues the expression of miR-29a-5p was down-regulated and the expression of TPX2 was up-regulated. We also found that low expression of TPX2 were associated with a better prognosis, and vice versa. Subsequent exogenous miR-29a-5p over-expression and TPX2 silencing could inhibit EC-derived cell proliferation and invasion, and to induce apoptosis. We also found that miR-29a-5p might target and repress TPX2, thereby inhibiting EC-derived cell proliferation and invasion and enhancing apoptosis. We conclude that miR-29a-5p could inhibit the proliferation and invasion of EC-derived cells and enhance the apoptosis of EC-derived cells via TPX2 down-regulation. A high TPX2 expression in primary EC tissues was found to be associated with a poor prognosis. As such, these biomarkers may serve as promising prognostic indicators.

ABBREVIATIONS: EC: Endometrial cancer; 3?-UTR: 3?-untranslated regions; TPX2: target protein for Xenopus kinesin-like protein 2; TCGA: the Cancer Genome Atlas; UCEC: uterine corpus endometrial carcinoma; CCK-8: cell counting kit-8; OD: optical density; FCM: flow cytometry; EMT: epithelial-mesenchymal transition  相似文献   
102.
Intratumoral heterogeneity of breast cancer remains a major challenge in successful treatment. Failure of cancer therapies can also be accredited to inability to systemically eradicate cancer stem cells (CSCs). Recent evidence points to the role of epithelial-mesenchymal transition (EMT) in expanding the pool of tumor cells with CSCs features. Thus, we assessed expression level as well as heterogeneity of CSCs markers in primary tumors (PT), lymph node metastasis (LNM), and circulating tumor cells (CTCs)–enriched blood fractions in order to correlate them with signs of EMT activation as well as clinicopathological data of breast cancer patients. Level of CSCs markers (ALDH1, CD44, CD133, OCT-4, NANOG) and EMT markers was quantified in PT (N=107), LNM (N=56), and CTCs-enriched blood fractions (N=85). Heterogeneity of CSCs markers expression within each PT and LNM was assessed by calculating Gini Index. Percentage of ALDH1-positive cells was elevated in PT in comparison to LNM (P = .005). However, heterogeneity of the four CSCs markers: ALDH1 (P = .019), CD133 (P = .009), OCT-4 (P = .027), and CD44 (P < .001) was decreased in LNM. Samples classified as mesenchymal (post-EMT) showed elevated expression of CSCs markers (OCT-4 and CD44 in PT; OCT-4 in LNM; ALDH1, OCT-4, NANOG, CD44 in CTCs). Patients with mesenchymal-like CTCs had worse prognosis than patients with epithelial-like or no CTCs (P = .0025). CSCs markers are enriched in PT, LNM, and CTCs with mesenchymal features, but their heterogeneity is decreased in metastatic lymph nodes. Mesenchymal CTCs phenotype correlates with poor prognosis of the patients.  相似文献   
103.
The misfolding and aggregation of proteins to form amyloid fibrils are associated with a number of debilitating, age-related diseases. Many of the proteins that form amyloid in vivo are lipid-binding proteins, accounting for the significant impact of lipids on the rate of formation and morphology of amyloid fibrils. To systematically investigate the effect of lipid-like compounds, we screened a range of amphipathic lipids and detergents for their effect on amyloid fibril formation by human apolipoprotein (apo) C-II. The initial screen, conducted using a set of amphiphiles at half critical micelle concentration, identified several activators and inhibitors that were selected for further analysis. Sedimentation analysis and circular dichroism studies of apoC-II at low, non-fibril-forming concentrations (0.05 mg/ml) revealed that all of the inhibitors induced the formation of apoC-II dimers enriched in α-helical content while the activators promoted the formation of stable apoC-II tetramers with increased β-structure. Kinetic analysis identified modulators of apoC-II fibril formation that were effective at concentrations as low as 10 μM, corresponding to a modulator-to-apoC-II ratio of approximately 1:10. Delayed addition of the test compounds after fibril formation had commenced allowed the effects of selected amphiphiles on fibril elongation to be determined separately from their effects on fibril nucleation. The results indicated that specific amphiphiles induce structural changes in apoC-II that cause separate and independent effects on fibril nucleation and elongation. Low-molecular-weight amphipathic lipids and detergents may serve as useful, stage-specific modulators of protein self-assembly and fibril formation in disease-prevention strategies.  相似文献   
104.
MicroRNAs function as an endogenous mode of fine gene regulation and have been implicated in multiple differentiation and developmental processes. In the present study, we investigated the role of miRNA-34 during chondrogenic differentiation of chick limb mesenchymal cells. We found that the expression of miR-34a increased upon chondrogenic inhibition. Blockade of miR-34a via PNA-based antisense oligonucleotides (ASOs) recovered the chondro-inhibitory actions of JNK inhibitor on migration of chondrogenic progenitors and the formation of precartilage condensation. Furthermore, we determined that EphA5 is a relevant target of miR-34a during chondrogenesis. MiR-34a was necessary and sufficient to down-regulate EphA5 expression, and up-modulation of EphA5 is sufficient to overcome inhibitory actions of miR-34 inhibition on cell migration and condensation of chick limb mesenchymal cells on collagen substrate. Taken together, our data suggest that miR-34a is a negative modulator of chondrogenesis, particularly in migration of chondroblasts, by targeting EphA5 and resulting inhibition of cellular condensation during chondrogenesis of chick limb mesenchymal cells.  相似文献   
105.
Sustained expression of the histone demethylase, KDM2B (Ndy1/FBXL10/JHDM1B), bypasses cellular senescence in primary mouse embryonic fibroblasts (MEFs). Here, we show that KDM2B is a conserved regulator of lifespan in multiple primary cell types and defines a program in which this chromatin-modifying enzyme counteracts the senescence-associated down-regulation of the EZH2 histone methyltransferase. Senescence in MEFs epigenetically silences KDM2B and induces the tumor suppressor miRNAs let-7b and miR-101, which target EZH2. Forced expression of KDM2B promotes immortalization by silencing these miRNAs through locus-specific histone H3 K36me2 demethylation, leading to EZH2 up-regulation. Overexpression of let-7b down-regulates EZH2, induces premature senescence, and counteracts immortalization of MEFs driven by KDM2B. The KDM2B-let-7-EZH2 pathway also contributes to the proliferation of immortal Ink4a/Arf null fibroblasts suggesting that, beyond its anti-senescence role in primary cells, this histone-modifying enzyme functions more broadly in the regulation of cellular proliferation.  相似文献   
106.
Eusynaptomyces benjaminii is described as a new species of the ectoparasiticLaboulbeniales (Ascomycetes). It exists only on two very restricted areas of the body (= position specifity) of its hostEnochrus testaceus (F.) (Coleoptera, Hydrophilidae): on the claws of the right fore-leg and on the lower side of the frontal border of the pronotum. In these two habitatsEu. benjaminii develops two extremely different growth-forms. Male and female hosts are parasitized on somewhat different parts of their body. This can be explained by their mating behaviour. The growth-forms ofEu. benjaminii are so different that one ignorant of the biology of hosts and parasites, might regard them as members of different species or even genera. They are to be interpreted as adaptations of one species to growth positions and mating behaviour of the host. There is no sex-of-host specifity as assumed by certain authors for several species of theLaboulbeniales.
  相似文献   
107.
Receptor interactions of parotid acinar cells with beta-agonists are mediated by cyclic 3',5'-monophosphate (cAMP) and expressed as cAMP-dependent protein kinase (cAPK) activation. In addition to its location in the cytoplasm, we have shown that cAPK is associated with the nuclear non-histone protein (NHP) fraction (0.35 M NaCl extract) of rat parotid acinar cells. Nuclei were prepared from isolated parotid acini with minimal contamination from other cell types or cytoplasmic components. The nuclear cAPK activity was inhibited by the thermostable inhibitor and was stimulated by the addition of exogenous cAMP to the assay, indicating that the enzyme is present in the holoenzyme form. Enzyme activity was not increased in the presence of detergent, suggesting that cAPK is not bound to the nuclear membrane. Photoaffinity-labeling studies with an 8-azido analog of cAMP showed that regulatory subunits of both type I and type II cAPK isozymes are present in parotid cell nuclei. Short-term in vitro stimulation of the acini with 10(-6) M isoproterenol did not alter cAPK activity in the nuclear fraction. These findings indicate that compartmentation of cAPK into nuclear and extranuclear locations in rat parotid acinar cells is similar to that of several other cell types which are responsive to hormonal stimulation.  相似文献   
108.
The developmental profiles of the binding of and opiate receptors agonists was investigated using the chick embryo brain. Binding of opioids was performed at embryonic days 5, 6, 15, 18, and 20 in the developing chick embryo brain. [3H]dihyromorphine was used as a ligand and with 5×10–7 M levorphanol for non-specific binding, and [3H](d-Ala2-d-Leu5)-enkephalin was used as a with 5×10–7 M (d-Ser-Gly-Phe-Leu-Thr)-enkephalin for non-specific binding. Crude membranes were prepared from whole brain at days, 5, 6 and cerebral hemispheres at days 15, 18, and 20 of embryonic age. Both and opiate receptors were present during early embryogenesis and as early as day 5. Analysis of binding sites revealed high and low affinity sites during early embryogenesis but only one site. By 18 days of embryonic age, only one site remained. This developmental change is interpreted as a transitory state of the receptor to the adult pattern. The presence of only one site is constant throughout embryonic age; it is high during early embryogenesis reaching a lower level by 18 days. The presence of a dual binding site pattern for the receptor in early embryogenesis is implicated to have a functional significance in the pluripotential role of the endogenous opioids in early development.  相似文献   
109.
目的:MiRNAs对于胎盘的形成和正常妊娠的维持起着至关重要的作用,它在胎盘中的表达失衡的可能导致了妊娠相关疾病的发生,我们前期研究发现miR-30a-3p在子痫前期患者胎盘上特异性高表达,推测miR-30a-3p可能参与了子痫前期的发生发展过程,本课题通过观察miR-30a-3p对人滋养肿瘤细胞系JEG-3细胞侵袭能力的影响,深入探讨miR-30a-3p在子痫前期发病过程中的作用。方法:应用瞬时转染技术在人滋养肿瘤细胞系JEG-3细胞中分别转染miR-30a-3p mimics、mimics NC为miR-30a-3p过表达组和阴性对照组,空白转染组为空白对照组,利用荧光实时定量PCR技术检测各组细胞中miR-30a-3p的表达,Transwell实验检测各组细胞侵袭能力的差别。结果:荧光实时定量PCR结果显示miR-30a-3p过表达组与阴性对照组、空白对照组相比miR-30a-3p的表达量明显升高,差异具有统计学意义(P〈0.05);Transwell实验结果显示miR-30a-3p过表达组细胞的侵袭能力与阴性对照组、空白对照组相比均有降低,差异具有统计学意义(P〈0.05)。阴性对照组与空白对照组的侵袭能力差异无统计学意义(P〉0.05)。结论:miR-30a-3p可以显著下调JEG-3细胞的侵袭力,miR-30a-3p有可能通过降低滋养细胞的浸润能力,导致滋养细胞对子宫肌层和螺旋动脉的浸润不足,造成"胎盘浅着床",从而在子痫前期的发病过程中发挥了重要的作用,miR-30a-3p有望成为诊治子痫前期疾病的靶点。  相似文献   
110.
目的:探讨中国汉族人群中miR-146aC〉G,miR-149T〉C基因多态性与缺血性脑卒中易感性的关系。方法:利用聚合酶链式反应-限制性片段长度多态性(PCR-RFLP)的方法检测196例缺血性脑卒中患者和205例健康对照中miR-146aC〉G,miR-149T〉C的基因型,统计学方法比较两组间基因型及等位基因分布差异。结果:miR-146aC〉G位点各基因型在病例组和对照组分布无明显差异,但等位基因G会增加缺血性脑卒中的患病风险;miR-149T〉C位点各基因型在病例组和对照组分布无明显差异。在分层分析中,miR-146aC〉G会增加女性和非高血压患者缺血性脑卒中的患病风险,miR-149T〉C会增加非高血压患者缺血性脑卒中的患病风险。结论:miR-146aG等位基因,miR-149C等位基因与汉族人群缺血性脑卒中易感性有一定的相关性。  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号