全文获取类型
收费全文 | 1647篇 |
免费 | 28篇 |
国内免费 | 5篇 |
专业分类
电工技术 | 123篇 |
化学工业 | 415篇 |
金属工艺 | 31篇 |
机械仪表 | 39篇 |
建筑科学 | 33篇 |
矿业工程 | 1篇 |
能源动力 | 68篇 |
轻工业 | 113篇 |
水利工程 | 1篇 |
石油天然气 | 1篇 |
无线电 | 145篇 |
一般工业技术 | 335篇 |
冶金工业 | 160篇 |
原子能技术 | 42篇 |
自动化技术 | 173篇 |
出版年
2022年 | 25篇 |
2021年 | 25篇 |
2020年 | 7篇 |
2019年 | 14篇 |
2018年 | 12篇 |
2017年 | 21篇 |
2016年 | 25篇 |
2015年 | 15篇 |
2014年 | 34篇 |
2013年 | 71篇 |
2012年 | 56篇 |
2011年 | 93篇 |
2010年 | 62篇 |
2009年 | 56篇 |
2008年 | 76篇 |
2007年 | 77篇 |
2006年 | 73篇 |
2005年 | 55篇 |
2004年 | 50篇 |
2003年 | 65篇 |
2002年 | 59篇 |
2001年 | 48篇 |
2000年 | 39篇 |
1999年 | 40篇 |
1998年 | 98篇 |
1997年 | 51篇 |
1996年 | 42篇 |
1995年 | 40篇 |
1994年 | 20篇 |
1993年 | 30篇 |
1992年 | 24篇 |
1991年 | 26篇 |
1990年 | 19篇 |
1989年 | 18篇 |
1988年 | 25篇 |
1987年 | 14篇 |
1986年 | 14篇 |
1985年 | 19篇 |
1984年 | 21篇 |
1983年 | 8篇 |
1982年 | 17篇 |
1981年 | 11篇 |
1980年 | 10篇 |
1979年 | 17篇 |
1978年 | 13篇 |
1977年 | 7篇 |
1976年 | 10篇 |
1975年 | 5篇 |
1974年 | 5篇 |
1973年 | 5篇 |
排序方式: 共有1680条查询结果,搜索用时 31 毫秒
61.
Maksudul M. Alam Osamu Ito Naoki Sakurar Hiroshi Moriyama 《Fullerenes, Nanotubes and Carbon Nanostructures》2013,21(6):1007-1024
Abstract Efficient electron-transfer reactions from three kind of tetraselenafulvalenes (TSeF's) to photoexcited triplet state of C60 or C70 in polar solvents have been confirmed by transient absorption spectroscopy observing the decay of 3C60*/3C70* and rise of C60 ??/C70 ??. Growth of single crystal seems to be stimulated by laser irradiation of the solution containing C60 and bis(ethylenedithio)tetraselena-fulvalene (BEDT-TSeF), in which C60 ?? was effectively formed. 相似文献
62.
63.
64.
65.
66.
Phase Relations and Volume Changes of Hafnia under High Pressure and High Temperature 总被引:1,自引:0,他引:1
Osamu Ohtaka Hiroshi Fukui Taichi Kunisada Tomoyuki Fujisawa Kenichi Funakoshi Wataru Utsumi Tetsuo Irifune Koji Kuroda Takumi Kikegawa 《Journal of the American Ceramic Society》2001,84(6):1369-1373
Using multi-anvil high-pressure devices and synchrotron radiation, X-ray in situ observations of HfO2 under high pressure and high temperature have been performed to investigate its phase relations and compression behavior. An orthorhombic phase (orthoI) is stable from 4 to 14.5 GPa below 1250°–1400°C and transforms to a tetragonal phase, which is one of the high-temperature forms of HfO2 , above these temperatures. Another orthorhombic phase (orthoII) with a cotunnite-type structure appears above 14.5 GPa. OrthoII is stable up to 1800°C at 21 GPa. OrthoII is quenchable to ambient conditions. The orthoI-to-orthoII transition is accompanied by ∼8 vol% decrease. The bulk moduli of orthoI and orthoII at room temperature are 220 and 312 GPa, respectively. This low compressibility of orthoII indicates that it is a potential candidate for very hard materials. 相似文献
67.
We evaluated the effects of seven mushroom extracts (Grifola frondosa, Pholiota nameko, Panellus serotinus, Hypsizygus marmoreus, Pleurotus cornucopiae, Armillaria mellea, and Flammulina velutipes) on cytotoxic activity and cytokine production of lamina propria leukocytes (LPLs) isolated from rat small (S) and large (L) intestinal mucosa. Boiling water extracts from seven species of mushrooms showed no direct cytotoxicity against the YAC-1 target cells. However, prominent increases of cytotoxicity were observed in S- and L-LPLs co-cultured with P. serotinus extract. Cytokine production (TNFα, IFNγ, IL-12 p70, and IL-4) of S- and L-LPLs was stimulated in response to P. cornucopiae extract. Mushroom extracts contributed to target cell adhesion and/or cytokine production in the effector cells. The promotion of cytotoxic activity in S- and L-LPLs was not necessarily related to β-glucan content of the mushroom. 相似文献
68.
Bulky End‐Capped [1]Benzothieno[3,2‐b]benzothiophenes: Reaching High‐Mobility Organic Semiconductors by Fine Tuning of the Crystalline Solid‐State Order
下载免费PDF全文
![点击此处可从《Advanced materials (Deerfield Beach, Fla.)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Guillaume Schweicher Vincent Lemaur Claude Niebel Christian Ruzié Ying Diao Osamu Goto Wen‐Ya Lee Yeongin Kim Jean‐Baptiste Arlin Jolanta Karpinska Alan R. Kennedy Sean R. Parkin Yoann Olivier Stefan C. B. Mannsfeld Jérôme Cornil Yves H. Geerts Zhenan Bao 《Advanced materials (Deerfield Beach, Fla.)》2015,27(19):3066-3072
69.
This study re-visits the effects of loading rate on sand behavior in view of seismic design of pile foundation. Based on an extensive literature review covering both element testing and model testing, the paper summarizes the current understanding of the loading rate effects. The paper then describes the development of test apparatus used in this study and presents the data obtained from a series of monotonically increasing triaxial compression tests on Toyoura sand, varying the strain rate in the range of 0.005%/s to 250%/s. A total of 36 tests were conducted on dry and saturated sand, both under drained and undrained conditions with two confining pressures. The experimental results confirm that the soil strength and the soil stiffness increase as the strain rate increase. This paper also concludes that the internal friction angle and deformation modulus increase when the strain rate is high. The implications of the loading rate effect on pile foundation design are then presented. 相似文献
70.
Poly(3-hexylthiophene-2,5-diyl) is among the most widely used conjugated polymers for opto-electronic applications. To enhance its properties, researchers have attempted to nanostructure this polymer using various processes including breath figure arrays, nanolithography and elaborated organic synthesis. We here demonstrate a simple process to nanostructure the conjugated polymer using self-assembly with polystyrene and selective removal of one of the phases. The influence of the molecular weight of each polymer on the thin film morphology was systematically studied by atomic force microscopy. Using this approach, we observe two types of nanostructure, namely, nanoporous and nanoisland structures, of which the dimensions can be tuned by modifying the molecular weight of each polymer in the blend. This simple process introduces a cost-effective alternative to produce thin films of conjugated polymer with average nano-features from 100 nm up to 500 nm which could be used in a wide range of applications. 相似文献