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   1094篇
  免费   23篇
  国内免费   3篇
电工技术   48篇
综合类   1篇
化学工业   282篇
金属工艺   25篇
机械仪表   20篇
建筑科学   24篇
能源动力   44篇
轻工业   84篇
无线电   91篇
一般工业技术   172篇
冶金工业   227篇
原子能技术   37篇
自动化技术   65篇
  2023年   3篇
  2022年   16篇
  2021年   20篇
  2020年   15篇
  2019年   5篇
  2018年   16篇
  2017年   9篇
  2016年   12篇
  2015年   17篇
  2014年   20篇
  2013年   48篇
  2012年   35篇
  2011年   46篇
  2010年   38篇
  2009年   32篇
  2008年   58篇
  2007年   60篇
  2006年   38篇
  2005年   39篇
  2004年   28篇
  2003年   41篇
  2002年   39篇
  2001年   25篇
  2000年   25篇
  1999年   27篇
  1998年   100篇
  1997年   48篇
  1996年   35篇
  1995年   30篇
  1994年   33篇
  1993年   33篇
  1992年   9篇
  1991年   12篇
  1990年   14篇
  1989年   10篇
  1988年   8篇
  1987年   3篇
  1986年   3篇
  1985年   11篇
  1984年   3篇
  1983年   6篇
  1982年   7篇
  1981年   9篇
  1980年   8篇
  1978年   5篇
  1977年   5篇
  1976年   9篇
  1975年   2篇
  1973年   2篇
  1969年   1篇
排序方式: 共有1120条查询结果,搜索用时 171 毫秒
1.
Abstract

The I-shaped cross-sectional beam of CFRP (CFRP I-beam) is usually manufactured by the continuous protrusion method. Carbon fibers can only be arranged in the longitudinal direction. The CFRP I-beam with arbitrary arrangement of carbon fiber was manufactured with applying the electro-activated deposition molding method. The carbon fiber fabric was immersed in the deposition solution and energized, epoxy resin precipitated around carbon fiber and impregnated. The resin-impregnated fabric was installed to the mold, and the CFRP I-beam was fabricated. The CFRP I-beam was subjected to three-point bending tests, and the relationship between load-deflection was simulated by finite-element analysis.  相似文献   
2.
Fluoroalkyl end-capped N-(1,1-dimethyl-3-oxobutyl)acrylamide oligomer [RF-(DOBAA) n -RF] reacted with tetraethoxysilane (TEOS) and silica nanoparticles in the presence of low-molecular weight biocides such as hibitane, hinokitiol, and hinokioil under alkaline conditions to afford RF-(DOBAA) n -RF/silica nanocomposites-encapsulated these biocides in excellent to moderate isolated yields. Fluoroalkyl end-capped N,N-dimethylacrylamide oligomer [RF-(DMAA) n -RF] and acrylic acid oligomer [RF-(ACA) n -RF]/silica nanocomposites-encapsulated hibitane were obtained under similar conditions. Dynamic light scattering measurements showed that the size of these fluorinated nanocomposites-encapsulated biocides thus obtained is nanometer size-controlled. Additionally, these fluorinated nanocomposites were shown to have a good dispersibility and stability in methanol and water. Of particular interest, these fluorinated nanocomposites-encapsulated biocides were found to have a good antibacterial activity against Staphylococcus aureus, and these nanocomposites were applied to the surface modification of traditional organic polymers such as poly(methyl methacrylate).  相似文献   
3.
The isochoric pressure of bcc Solid3He in the vicinity of the triple point has been measured by changing the temperature stepwisely and waiting for thermal equilibrium. We observed anomalous pressure kinks of the temperature dependence in the paramagnetic region near the triple point. This anomaly appeared at 0.37 to 0.40 tesla, and disappeared below 0.36 tesla. Moreover, critical phenomena at the transition point from the paramagnetic phase (PP) to the high field phase was observed and the phase line curves toward the PP side.  相似文献   
4.
The performances of a hydrogen-fueled gas turbine cycle equipped with an intercooler, regenerator, hydrogen turbine and recuperative hydrogen heater are analyzed. The intercooler is very effective to prevent the condensation and freezing of water vapor in cooling the suction air. The operation of hydrogen turbine in low-temperature range can also be prevented by adopting hydrogen heater. Thermodynamic analysis has revealed that the thermal efficiency and the specific output are considerably improved compared to those of the simple gas turbine cycle.  相似文献   
5.
New fluoroalkyl end-capped fullerene cooligomers were prepared by the reactions of fluoroalkanoyl peroxides with fullerene and comonomers such as acryloylmorpholine, N,N-dimethylacrylamide and acrylic acid. These fluorinated fullerene cooligomers were easily soluble in water and common organic solvents, and were able to reduce the surface tensions of both water and benzene, quite effectively. Additionally, these fullerene cooligomers were found to form a stable monomolecular film at the air-water interface, and the modified polystyrene surface treated with these cooligomers was shown to have a strong hydrophilicity with good oil repellency.  相似文献   
6.
The cell leakage of a stacked trench capacitor (STT) cell has been investigated. The major leakage mechanisms of the STT are trench-to-trench leakage, trench junction leakage, and LOCOS isolation leakage. It is shown that compared to a conventional trench capacitor, the trench-to-trench leakage current is reduced and high punchthrough voltage is obtained. Therefore, the trench-to-trench spacing can be reduced 0.1 μm shorter than that of the trench capacitor. These reductions result from the STT structure itself. The surface leakage current, which is the dominant leakage current in the trench capacitor, does not flow in the STT. This paper also describes the effect of the sidewall damage caused by trench etching on the trench junction leakage. Reactive ion etching (RIE) produces deep levels just beneath the trench surface. But, the trench junction of the STT is not influenced by these deep levels because the trench surface is covered by a n-diffused layer. This paper also investigates the relationship between the cell leakage and the retention time. At DRAM operation temperatures, LOCOS isolation leakage is dominant rather than trench junction leakage. Therefore, the deeper trench can increase the storage capacitance and improve the retention time  相似文献   
7.
We developed a wide-striped laser diode integrated with a microlens that provides good focusing characteristics through a small focusing spot. We calculated and demonstrated that a 60-μm-wide core and a 1.9-μm-high ridge is the best structure for fundamental index-guiding mode oscillation of a wide-striped laser diode. We integrated a wide-striped laser diode with the developed microlens in the Fresnel diffraction held, and demonstrated that a device with a 60-μm-wide core has a minimum focusing spot width of 2.0 μm in the horizontal direction. Also, we estimated the wavefront in the Fresnel diffraction field from the working distance error of a lens designed for a collimated incident beam, and showed that the working distance error, focusing spot width, and sidelobe can be improved by this estimated wavefront  相似文献   
8.
9.
An integrated laser blood flowmeter   总被引:1,自引:0,他引:1  
We have constructed a very small and lightweight blood flowmeter using micromachining and surface mounting techniques for a wearable health monitoring system. The hybrid integrated structure of the optical system incorporates a InGaAsP-InP distributed feedback laser diode (DFB-LD) with a wavelength of 1310 nm, an edge-illuminated photodiode (PD) and a polyimide waveguide on silicon substrate (2 mm /spl times/ 3 mm). This integrated flowmeter can be positioned directly on the tissue and permits real-time monitoring of capillary microcirculation. In-vivo measurements of blood perfusion in a finger confirm the feasibility of the blood flowmeter.  相似文献   
10.
Fluoroalkanoyl peroxides reacted with FULLERENES [fullerene (C60) and commercially available fullerenes (Nanom MixTR and Nanom BlackTR)] and radical polymerizable comonomers such as acrylic acid, N,N-dimethylacrylamide, N-(1,1-dimethyl-3-oxobutyl)acrylamide, and acryloylmorpholine to afford fluoroalkyl end-capped cooligomers having FULLERENES in the main chain under very mild conditions. Fluoroalkyl end-capped Nanom Mix and Nanom Black cooligomers thus obtained were found to exhibit a similar solubility to that of the corresponding fluoroalkyl end-capped cooligomers having fullerene in the main chain. These fluorinated FULLERENES cooligomers were found to form the nanometer size-controlled self-assembled cooligomeric aggregates in aqueous solutions. These fluoroalkyl end-capped FULLERENES cooligomers were more effective for solubilizing fullerene, Nanom Mix and Nanom Black into water, compared to those of the corresponding fluoroalkyl end-capped homooligomers having no FULLERENES in the main chain. Fluoroalkyl end-capped fullerene- and Nanom Mix-acrylic acid cooligomers were found to exhibit fluorescence spectra related to fullerene and Nanom Mix in cooligomers, respectively, in aqueous solutions. Additionally, these fluorinated fullerene- and Nanom Mix-acrylic acid cooligomers were able to increase chemiluminescence intensity related to luminol, effectively, compared to the corresponding fluorinated acrylic acid homooligomers.  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