全文获取类型
收费全文 | 1919篇 |
免费 | 253篇 |
国内免费 | 290篇 |
专业分类
电工技术 | 21篇 |
综合类 | 99篇 |
化学工业 | 449篇 |
金属工艺 | 86篇 |
机械仪表 | 28篇 |
矿业工程 | 3篇 |
能源动力 | 12篇 |
轻工业 | 4篇 |
石油天然气 | 1篇 |
武器工业 | 3篇 |
无线电 | 951篇 |
一般工业技术 | 678篇 |
冶金工业 | 104篇 |
原子能技术 | 10篇 |
自动化技术 | 13篇 |
出版年
2024年 | 6篇 |
2023年 | 51篇 |
2022年 | 45篇 |
2021年 | 60篇 |
2020年 | 73篇 |
2019年 | 90篇 |
2018年 | 80篇 |
2017年 | 96篇 |
2016年 | 92篇 |
2015年 | 72篇 |
2014年 | 90篇 |
2013年 | 109篇 |
2012年 | 174篇 |
2011年 | 170篇 |
2010年 | 120篇 |
2009年 | 152篇 |
2008年 | 130篇 |
2007年 | 99篇 |
2006年 | 116篇 |
2005年 | 94篇 |
2004年 | 79篇 |
2003年 | 53篇 |
2002年 | 40篇 |
2001年 | 66篇 |
2000年 | 63篇 |
1999年 | 30篇 |
1998年 | 27篇 |
1997年 | 30篇 |
1996年 | 46篇 |
1995年 | 25篇 |
1994年 | 13篇 |
1993年 | 13篇 |
1992年 | 12篇 |
1991年 | 12篇 |
1990年 | 6篇 |
1989年 | 7篇 |
1988年 | 1篇 |
1987年 | 1篇 |
1986年 | 4篇 |
1985年 | 2篇 |
1984年 | 2篇 |
1983年 | 2篇 |
1982年 | 1篇 |
1981年 | 1篇 |
1979年 | 4篇 |
1978年 | 3篇 |
排序方式: 共有2462条查询结果,搜索用时 31 毫秒
101.
利用物理热蒸发法制备大规模的蒲公英状的ZnO纳米锥,利用荧光光谱仪对ZnO纳米锥进行了光致发光性能测试.针对现有的丝网印刷碳纳米管(CNTs)薄膜需要各种后处理工艺后才能改善其场发射特性的问题,提出了一种不需任何后处理丝网印刷ZnO纳米锥的浆料配制工艺.用该工艺制备的丝网印刷ZnO纳米锥的场发射特性测试表明,ZnO纳米锥与制浆剂质量比为3∶5的薄膜的开启场强最低为2.25V/μm(电流密度为1μA/cm2),在4.6V/μm场强下,阳极荧光粉的发光点亮度高且分布均匀.说明该方法成本低,工艺简单,无需任何后处理,在ZnO纳米锥场发射显示器的制作中有很好的实际应用价值. 相似文献
102.
氧化锌纳米棒有序阵列的制备及表征 总被引:2,自引:0,他引:2
氧化锌是一种重要的化合物半导体,其低维结构在微电子器件领域具有潜在的应用前景.在温和的条件下利用软化学方法在沉积了单层ZnO颗粒膜的玻璃衬底上制备了直径为70~300nm,长约1μm的氧化锌纳米棒有序阵列,讨论了颗粒膜对阵列生长的作用以及水浴温度对晶体结构和形貌的影响.结果表明,产物为纤锌矿结构;ZnO颗粒膜为阵列的生长提供了分布均匀且固定的形核中心,对阵列的有序生长起诱导作用;随着反应温度的升高,阵列直径变小且排列更加有序,但过高的温度会抑制ZnO晶体内部的c轴择优取向作用.研究了ZnO阵列的光致发光特性,初步讨论了其发光机理. 相似文献
103.
104.
105.
Corneliu Hamciuc Elena Hamciuc Diana Serbezeanu Tachita Vlad‐Bubulac Maria Cazacu 《Polymer International》2011,60(2):312-321
New phosphorus‐containing poly(ester‐imide)‐polydimethylsiloxane copolymers were prepared by solution polycondensation of 1,4‐[2‐(6‐oxido‐6H‐dibenz < c,e > < 1, 2 > oxaphosphorin‐6‐yl)]naphthalene‐bis(trimellitate) dianhydride with a mixture of an aromatic diamine (1,3‐bis(4‐aminophenoxy)benzene) and α,ω‐bis(3‐aminopropyl)oligodimethylsiloxane of controlled molecular weight, in various ratios. Poly(amic acid) intermediates were converted quantitatively to the corresponding polyimide structures using a solution imidization procedure. The polymers are easily soluble in polar organic solvents, such as N‐methyl‐2‐pyrrolidone and N,N‐dimethylformamide, as well as in less polar solvents such as tetrahydrofuran. They show good thermal stability, the decomposition temperature being above 370 °C. The glass transition temperatures are in the range 165–216 °C. Solutions of the polymers in N‐methyl‐2‐pyrrolidone exhibit photoluminescence in the blue region. Copyright © 2010 Society of Chemical Industry 相似文献
106.
107.
The carrier cooling and the carrier relaxation of an InN thin film illuminated with two excitation energies of 1.53 and 3.06 eV were studied by an ultrafast time-resolved photoluminescence upconversion apparatus. The hot phonon effect could be accounted for longer effective phonon emission times as compared to the theoretical prediction. The rise time and the LO phonon emission time for 3.06 eV excitation were much smaller than those for 1.53 eV excitation. These differences were attributed to the intervalley scattering between the Γ1 and Γ3 valleys in InN when carriers were excited with the energy of 3.06 eV. The intervalley scattering times of 250 fs and 2 ps were estimated for the intervalley scattering from the Γ1 to Γ3 valley and the reversed scattering process, respectively. 相似文献
108.
《国际聚合物材料杂志》2012,61(10):786-792
Optical properties of a green fluorescent protein (GFP) are examined using optical absorption, circular dichroism (CD), and circular polarized luminescence (CPL) spectroscopies. The GFP has chiroptical activity and exhibits green circular polarized emission, although the g em-factor is small. Poly(vinyl alcohol) (PVA)/GFP composite films are prepared to attempt long-term preservation of the GFP emission activity. After five years, the transparent PVA/GFP composite film still exhibits stable fluorescence that appears similar to the emission from the Aequorea jellyfish. 相似文献
109.
Yu. I. Mazur V. G. Dorogan E. Marega Jr D. F. Cesar V. Lopez-Richard G. E. Marques Z. Ya. Zhuchenko G. G. Tarasov G. J. Salamo 《Nanoscale research letters》2010,5(6):991-1001
Multilayer In0.4Ga0.6As/GaAs quantum dot (QD) chain samples are investigated by means of cw and time-resolved photoluminescence (PL) spectroscopy in order to study the peculiarities of interdot coupling in such nanostructures. The temperature dependence of the PL has revealed details of the confinement. Non-thermal carrier distribution through in-chain, interdot wave function coupling is found. The peculiar dependences of the PL decay time on the excitation and detection energies are ascribed to the electronic interdot coupling and the long-range coupling through the radiation field. It is shown that the dependence of the PL decay time on the excitation wavelength is a result of the superradiance effect. 相似文献
110.
《Ceramics International》2017,43(14):10637-10644
In this paper we have studied the properties of ZnO ceramics sintered from the ZnO-Zn nanopowders (NPs) produced by a pulsed electron beam evaporation of heterogeneous targets (oxide or metal) and to establish the influence of NPs prehistory on the luminescence and dilatometry properties of ceramics produced from them. Pressing was performed on uniaxial presses: static and the magnetic pulsed one. Sintering of ceramics was produced in air by heating to 1200 °C in 60 min. Maximal density of the ceramics did not exceed 81,25% of the theoretical density. The behavior of the shrinkage curves of ZnO-Zn NPs depends on their prehistory. Evolution of properties of ZnO-Zn nanoparticles (NPles) during annealing in air is studied by XRD and pulsed cathodoluminescence methods. The suppression of the ultraviolet emission in NP obtained by electron beam evaporation, and in ceramics sintered of them was established. 相似文献