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   183篇
  免费   5篇
  国内免费   1篇
电工技术   3篇
化学工业   55篇
金属工艺   6篇
机械仪表   4篇
建筑科学   3篇
能源动力   5篇
轻工业   24篇
石油天然气   1篇
无线电   3篇
一般工业技术   33篇
冶金工业   26篇
原子能技术   4篇
自动化技术   22篇
  2023年   4篇
  2022年   7篇
  2021年   12篇
  2020年   13篇
  2019年   13篇
  2018年   11篇
  2017年   13篇
  2016年   10篇
  2015年   6篇
  2014年   5篇
  2013年   7篇
  2012年   8篇
  2011年   11篇
  2010年   11篇
  2009年   8篇
  2008年   10篇
  2007年   4篇
  2006年   1篇
  2004年   2篇
  2003年   1篇
  2002年   1篇
  2000年   1篇
  1999年   1篇
  1998年   8篇
  1997年   8篇
  1996年   2篇
  1995年   2篇
  1993年   1篇
  1991年   1篇
  1990年   2篇
  1981年   1篇
  1977年   2篇
  1976年   1篇
  1974年   1篇
排序方式: 共有189条查询结果,搜索用时 31 毫秒
71.
In the present era of advanced technology, the surge for suitable multifunctional materials capable of operating above 300 °C has increased for the utilization of high-temperature piezoelectric devices. For this purpose, a pseudo-tetragonal phased CaBi4Ti3.98 (Nb0.5Fe0.5)0.02O15:xwt%MnO2 (CBTNF:xMn), with x = 0–0.20, ceramic system has been engineered for the investigation of structural, ferroelectric, dielectric and high-temperature-dependent piezoelectric properties. XRD analysis confirms that low-content Mn-ion insertion at the lattice sites of CBTNF does not distort the pseudo-tetragonal phase lattice of CBTNF:xMn ceramics, but enhances the functional behavior of the ceramic system, specifically at x = 0.15 wt%Mn. Compared to pure CBT and CBTNF ceramics, CBTNF:0.15Mn has demonstrated a highly dense relative density (~96%), a saturated polarization (PS) of 15.89 µC/cm2, a storage energy density (WST) of ~1.82 J/cm3, an energy-conversion efficiency (ƞ) of ~51% and an upgraded piezoelectric behavior (d33) of 27.1 pC/N at room temperature. Sharp temperature-dependent dielectric constant (εr) peaks display the solid ferroelectric behavior of the CBTNF:0.15Mn sample with a Curie temperature (TC) of 766 °C. The thermally stable piezoelectric performance of the CBTNF:0.15Mn ceramic was observed at 600 °C, with just a 0.8% d33 loss (25 pC/N). The achieved results signify that multi-valence Mn ions have effectively intercalated at the lattice sites of the pseudo-tetragonal phased CBTNF counterpart and enhanced the multifunctional properties of the ceramic system, proving it to be a durable contender for utilization in energy-storage applications and stable high-temperature piezoelectric applications.  相似文献   
72.
73.
74.
Transmitter release was elicited in two ways from cultured cells filled with acetylcholine: (a) in a biochemical assay by successive addition of a calcium ionophore and calcium and (b) electrophysiologically, by electrical stimulation of individual cells and real-time recording with an embryonic Xenopus myocyte. Glioma C6-Bu-1 cells were found to be competent for Ca(2+)-dependent and quantal release. In contrast, no release could be elicited from mouse neuroblastoma N18TG-2 cells. However, acetylcholine release could be restored when N18TG-2 cells were transfected with a plasmid coding for mediatophore. Mediatophore is a protein of nerve terminal membranes purified from the Torpedo electric organ on the basis of its acetylcholine-releasing capacity. The transfected N18TG-2 cells expressed Torpedo mediatophore in their plasma membrane. In response to an electrical stimulus, they generated in the myocyte evoked currents that were curare sensitive and calcium dependent and displayed, discrete amplitude levels, like in naturally occurring synapses.  相似文献   
75.
76.
The phase behaviour and the mechanical properties of binary blends composed of poly(ether ether ketone) and poly(ether sulphone) have been studied both in the amorphous state and after crystallization of poly(ether ether ketone).Differential scanning calorimetry and dynamical mechanical analysis clearly show the existence of phase separation in the blends. Density measurements confirm the absence of strong interactions between the blend components, as well as the slight effect of PES on the crystallization of PEEK.The mechanical properties of the quenched, amorphous blends remain surprisingly good in spite of the observed immiscibility, however, slowly cooled, crystalline blends appear as brittle materials.  相似文献   
77.
A case of bilateral facial atrophy diagnosed as atrophic connective tissue panniculitis is presented. Reconstruction of both cheeks was performed with two staged latissimus dorsi muscle flaps. The initial good result on the right cheek deteriorated as the disease continued to progress after surgery. The good result on the left cheek, however, remained stable. Detailed clinical examinations, laboratory analysis, and deep biopsies from the affected areas are important for accurate diagnosis. Reconstructive procedures should be delayed while the disease is still active.  相似文献   
78.
79.
Recently new operations have been defined for soft sets. In this paper, we study some important properties associated with these new operations. A collection of all soft sets with respect to new operations give rise to four idempotent monoids. Then with the help of these monoids we can study semiring (hemiring) structures of soft sets. Some of these semirings (hemirings) are actually lattices. Finally, we show that soft sets with a fixed set of parameters are MV algebras and BCK algebras.  相似文献   
80.
ABSTRACT

The combination of polymeric and inorganic fillers inside mixed matrix membranes (MMMs) becomes a hot research topic due to the gas permeability-selectivity trade-off in polymeric membranes. Until recently, the problem of voids hampers the real application of MMMs, hence deep understanding on polymer-particle compatibility is required. This study focuses on the synthesis and characterization of polysulfone and cellulose acetate-based MMMs that combined with ZIF-8 and TiO2 particles. ZIF-8 dispersed more uniform than TiO2. The crystallinity of MMMs was higher than pure polymeric membrane. In addition, micro voids in MMMs resulted a slight decrease in CO2/N2 selectivity (from 15 to 12).  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