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   62篇
  免费   2篇
电工技术   1篇
化学工业   11篇
金属工艺   1篇
机械仪表   2篇
建筑科学   5篇
轻工业   5篇
无线电   5篇
一般工业技术   28篇
自动化技术   6篇
  2023年   5篇
  2022年   2篇
  2021年   2篇
  2020年   2篇
  2019年   2篇
  2018年   4篇
  2017年   2篇
  2016年   1篇
  2015年   3篇
  2014年   2篇
  2013年   2篇
  2012年   2篇
  2011年   8篇
  2010年   5篇
  2009年   1篇
  2008年   4篇
  2007年   1篇
  2006年   5篇
  2005年   4篇
  2004年   2篇
  2003年   2篇
  2001年   1篇
  1999年   1篇
  1994年   1篇
排序方式: 共有64条查询结果,搜索用时 281 毫秒
1.
Regulatory changes occurring early in colorectal cancer development remain poorly investigated. Since the majority of cases develop from polyps in the adenoma-carcinoma transition, a search of early molecular features, such as aberrations in miRNA expression occurring prior to cancer development, would enable identification of potentially causal, rather than consequential, candidates in the progression of polyp to cancer. In the current study, by employing small RNA-seq profiling of colon biopsy samples, we described differentially expressed miRNAs and their isoforms in the adenoma-carcinoma transition. Analysis of healthy-adenoma-carcinoma sequence in an independent validation group enabled us to identify early deregulated miRNAs including hsa-miR-1246 and hsa-miR-215-5p, the expressions of which are, respectively, gradually increasing and decreasing. Loss-of-function experiments revealed that inhibition of hsa-miR-1246 lead to reduced cell viability, colony formation, and migration rate, thereby indicating an oncogenic effect of this miRNA in vitro. Subsequent western blot and luciferase reporter assay provided evidence of hsa-miR-1246 being involved in the regulation of target AXIN2 and CFTR genes’ expression. To conclude, the present study revealed possible involvement of hsa-miR-1246 in early colorectal cancer development and regulation of tumor suppressors AXIN2 and CFTR.  相似文献   
2.
In this work dielectric properties of Bi1.5Zn1?xLixNb1.5O7?xFx with x = 0.25 were investigated in a 20 Hz–12 GHz frequency and 120–500 K temperature range and compared to that of regular cubic BZN (when x = 0). Measurements showed that both ceramics have dipolar glass type dielectric dispersion with wide relaxation time distributions. Mean relaxation time follows Arrhenius law in the investigated frequency range, although Vogel–Fulcher law was anticipated.  相似文献   
3.
Source-based radiometry requires reliable transfer standards which are easy to handle. For low irradiances in the UV spectral range, 30 W deuterium lamps are commonly used. However, for the growing field of high UV irradiance applications, new high power standards are required. Here we report on a Xe-Hg lamp system which has been characterised and improved to match the high requirements of a working standard. For this purpose, several parameters of the system such as lamp stability, re-ignition reproducibility, irradiance uniformity and usability have been investigated. Components for the customised light guide-based output optics have been selected with the help of extensive characterisations. The resulting lamp system can be used for a high-grade instrument calibration at high UV irradiance levels.  相似文献   
4.
Ripples are formed on the surface of solid materials after interaction with laser pulses of high intensity/irradiance. When ultra-short sub-1 ps laser pulses are used, the observed morphology of ripples on surfaces becomes much more complex as compared with ripples formed by long laser pulses. Uniquely for the short laser pulses, ripples can be formed in the bulk. A better understanding of the fundamentals of light-matter interaction in ripples formation is strongly required. Experimentally observed ripples and dependence of their parameters on laser fabrication conditions and material properties are summarized first. Then, a critical review of relevant ripple formation mechanisms is presented, discussed, and formation conjectures are presented.  相似文献   
5.
The mechanism of the fine ripples, perpendicular to laser polarization, on the surface of (semi)transparent materials with period smaller than the vacuum wavelength, λ, of the incident radiation is proposed and experimentally validated. The sphere-to-plane transformation of nanoplasma bubbles responsible for the in-bulk ripples accounts for the fine ripples on the surface of dielectrics and semiconductors. The mechanism is demonstrated for 4H:SiC and sapphire surfaces using 800 nm/150 fs and 1030 nm/300 fs laser pulses. The ripples are pinned to the smallest possible standing wave cavity inside material of refractive index n. This defines the corresponding period, Λ = (λ/n)/2, of a light standing wave with intensity, E(2), at the maxima of which surface ablation occurs. The mechanism accounts for the fine ripples at the breakdown conditions. Comparison with ripples recorded on different materials and via other mechanisms using femtosecond pulses is presented and application potential is discussed.  相似文献   
6.
Patch recovery based on superconvergent derivatives and equilibrium (SPRE), an enhancement of the Superconvergent Patch Recovery (SPR), is studied for linear elasticity problems. The paper also presents a further improvement for recovery of derivatives near boundaries, SPREB, where either tractions or displacements are prescribed. This is made by inclusion of weighted residual errors at boundary points in the patch recovery. A pronounced improvement in the post processed gradients of the finite element solution is observed by this method.  相似文献   
7.
Extreme confinement of electromagnetic waves and mechanical displacement fields to nanometer dimensions through plasmonic nanostructures offers unprecedented opportunities for greatly enhanced interaction strength, increased bandwidth, lower power consumption, chip-scale fabrication, and efficient actuation of mechanical systems at the nanoscale. Conversely, coupling mechanical oscillators to plasmonic nanostructures introduces mechanical degrees of freedom to otherwise static plasmonic structures thus giving rise to the generation of extremely large resonance shifts even for minor position changes. This nanoscale marriage of plasmonics and mechanics has led to the emergence of a new field of study called plasmomechanics that explores the fundamental principles underneath the coupling between light and plasmomechanical nanoresonators. In this review, both the fundamental concepts and applications of plasmomechanics as an emerging field of study are discussed. After an overview of the basic principles of plasmomechanics, the active tuning mechanisms of plasmonic nano-mechanical systems are extensively analyzed. Moreover, the recent developments on the practical implications of plasmomechanic systems for such applications as biosensing and infrared detection are highlighted. Finally, an outlook on the implications of the plasmomechanical nanosystems for development of point-of-care diagnostic devices that can help early and rapid detection of fatal diseases are forwarded.  相似文献   
8.
Journal of Materials Science: Materials in Electronics - A systematic study of the GaN epitaxial lateral overgrowth (ELO) of the focused ion beam (FIB) patterned sapphire substrate is presented....  相似文献   
9.
9-Aryl[3,3′]bicarbazolyl derivatives containing reactive functional groups were synthesized by the multi-step synthetic rout. The monomers were examined by various techniques including thermogravimetry, differential scanning calorimetry, UV and fluorescence spectrometry as well as electron photoemission and time of flight techniques. The electron photoemission spectra of the layers showed the ionisation potentials of 5.2–5.5 eV. Time-of-flight hole drift mobilities in amorphous layers of bisphenol Z polycarbonate containing 50 wt. % of the electroactive materials exceed 10−5 cm2/Vs at high electric fields.  相似文献   
10.
The growing diversity of disciplines, participants, tasks, tools and events associated with project management at the design and construction stages, the increasing pressure of costing competition and tighter production deadlines, as well as continually increasing quality requirements and the need for technological enhancements, are the driving force of information modeling and numerical simulation in the construction industry. When choosing the most effective investment project in construction, a major problem associated with the actual demand for resources is underestimated. In order to solve this problem in the most effective way, the application programs, covering virtually every phase of the specific construction product development, e.g. planning, design, cost estimation, scheduling, fabrication, construction, maintenance and facility management were developed and supplemented with the calculation of the demand for resources, comparison of alternatives and determination of the duration of all the stages of the project life. Theoretical principles and practical innovative applications of building information modeling and construction process simulation technique, used to determine the most effective alternative of the project by applying the appropriate multiple criteria evaluation methods, are considered in the article.  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