全文获取类型
收费全文 | 969篇 |
免费 | 34篇 |
国内免费 | 4篇 |
专业分类
化学 | 589篇 |
晶体学 | 21篇 |
力学 | 25篇 |
数学 | 68篇 |
物理学 | 108篇 |
无线电 | 196篇 |
出版年
2023年 | 6篇 |
2022年 | 7篇 |
2021年 | 20篇 |
2020年 | 12篇 |
2019年 | 7篇 |
2018年 | 10篇 |
2017年 | 13篇 |
2016年 | 22篇 |
2015年 | 15篇 |
2014年 | 38篇 |
2013年 | 58篇 |
2012年 | 63篇 |
2011年 | 71篇 |
2010年 | 39篇 |
2009年 | 36篇 |
2008年 | 60篇 |
2007年 | 47篇 |
2006年 | 46篇 |
2005年 | 54篇 |
2004年 | 48篇 |
2003年 | 40篇 |
2002年 | 49篇 |
2001年 | 41篇 |
2000年 | 42篇 |
1999年 | 32篇 |
1998年 | 15篇 |
1997年 | 18篇 |
1996年 | 20篇 |
1995年 | 12篇 |
1994年 | 8篇 |
1993年 | 8篇 |
1992年 | 4篇 |
1991年 | 3篇 |
1990年 | 2篇 |
1989年 | 3篇 |
1988年 | 4篇 |
1987年 | 2篇 |
1986年 | 5篇 |
1985年 | 3篇 |
1984年 | 3篇 |
1981年 | 3篇 |
1978年 | 4篇 |
1976年 | 1篇 |
1975年 | 3篇 |
1974年 | 1篇 |
1973年 | 2篇 |
1972年 | 1篇 |
1970年 | 2篇 |
1968年 | 1篇 |
1967年 | 2篇 |
排序方式: 共有1007条查询结果,搜索用时 15 毫秒
281.
Suh Y.S. Carroll M.S. Levy R.A. Sahiner M.A. Bisognin G. King C.A. 《Electron Devices, IEEE Transactions on》2005,52(1):91-98
Boron and phosphorus implants into germanium and silicon with energies from 20 to 320 keV and ion doses from 5/spl times/10/sup 13/ to 5/spl times/10/sup 16/ cm/sup -2/ were characterized using secondary ion mass spectrometry. The first four moments of all implants were calculated from the experimental data. Both the phosphorus and boron implants were found to be shallower in the germanium than in the silicon for the same implant parameters and high hole concentrations, as high as 2/spl times/10/sup 20/ cm/sup -3/, were detected by spreading resistance profiling immediately after boron implants without subsequent annealing. Channeling experiments using nuclear reaction analysis also indicated high substitutional fractions (/spl sim/19%) even in the highest dose case immediately after implant. A greater straggle (second moment) is, however, observed in the boron implants in the germanium than in the silicon despite having a shorter projected range in the germanium. Implant profiles predicted by Monte Carlo simulations and Lindhard-Scharff-Schiott theory were calculated to help clarify the implant behavior. Finally, the experimentally obtained moments were used to calculate Pearson distribution fits to the boron and phosphorus implants for rapid simulation of nonamorphizing doses over the entire energy range examined. 相似文献
282.
Jin‐Woong Kim Jung‐Eun Lee Jee‐Hyun Ryu Jong‐Suk Lee Su‐Jin Kim Sang‐Hoon Han Ih‐Seop Chang Hak‐Hee Kang Kyung‐Do Suh 《Journal of polymer science. Part A, Polymer chemistry》2004,42(10):2551-2557
A new colloidal silver system is presented in which a fine colloidal silver is in situ deposited onto functionalized porous poly(ethylene glycol dimethacrylate) [poly(EGDMA)] microspheres. The effectiveness of the silver deposition has been investigated through an examination of the surface characteristics of poly(EGDMA) microspheres. The result reported in this study demonstrate that the control of the surface area and surface functionality (in this study, a hydroxyl group) of poly(EGDMA) microspheres is an important factor that practically determines the degree of deposition of colloidal silver. X‐ray analysis has shown that silver nanoparticles are dispersed evenly on inner and outer surfaces and have a face center cubic phase. Preservation testing has shown that silver‐containing poly(EGDMA) microspheres have powerful antibacterial properties and, therefore, have significant potential as new preservatives. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 2551–2557, 2004 相似文献
283.
Jongsoo Kim Robert C. Leachman Byungkyoo Suh 《The Journal of the Operational Research Society》1996,47(12):1516-1525
We propose a policy for controlling the release of raw wafers into semiconductor wafer fabrication lines. The proposed policy exploits up-to-date factory floor information gathered by tracking systems in order to calculate the timing and amount of new releases to minimize mean flow times and mean tardiness while maintaining the maximum output rates of the system. Extensive computer experiments show that the proposed policy results in at least 23.0 and 17.9% improvements on average in mean waiting time and mean tardiness respectively compared to existing release rules. 相似文献
284.
285.
Suhee Song Youngeup Jin Sun Hee Kim Joo Young Shim Sooyeon Son Il Kim Kwanghee Lee Hongsuk Suh 《Journal of polymer science. Part A, Polymer chemistry》2009,47(23):6540-6551
The present investigation deals with the synthesis, characterization, and EL properties of new polyfluorenevinylenes, CzCNPFVs, with cyano‐substituted vinylene unit and carbazole pendant. In CzCNPFVs, synthesized by the Knoevenagel condensation, the carbazole pendant was introduced to improve the efficiency of reported CNPFV. The PL emission spectra of the CzCNPFVs in chloroform solution show maximum peaks at 476–479 nm. In thin films, maximum peaks of the CzCNPFVs appeared at 501–504 nm, red‐shifted around 25 nm as compared to those in solution. The emission maxima of the EL spectra of the polymers appear at around 496–504 nm. The maximum luminescence (Lmax) of CzCNPFV2 of the device with the configuration of ITO/PEDOT/CzCNPFVs/Ca/Al is 1724 cd/m2 at 8 V. The maximum luminescence efficiency of CzCNPFV1 is 0.18 cd/A. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 6540–6551, 2009 相似文献
286.
Bum-Seok Suh Dong-Seok Hyun 《Industrial Electronics, IEEE Transactions on》1997,44(1):107-115
This paper deals with a new multilevel high-voltage source inverter with gate-turn-off (GTO) thyristors. Recently, a multilevel approach seemed to be the best suited for implementing high-voltage power conversion systems because it leads to a harmonic reduction and deals with safe high-power conversion systems independent of the dynamic switching characteristics of each power semiconductor device. A conventional multilevel inverter has some problems; voltage unbalance between DC-link capacitors and larger blocking voltage across the inner switching devices. To solve these problems, the novel multilevel inverter structure is proposed 相似文献
287.
The multilayer of Ta/NiFeMo/Ru/Co3Pt was sputter deposited on the Si (1 0 0) wafer. Using the NiFeMo buffer layer greatly enhanced the texture of Co3Pt layer. The enhanced texture increased the perpendicular magnetic anisotropy of Co3Pt. According to the VSM and XRD results, only the 5 nm of NiFeMo was good enough to produce the texture and perpendicular anisotropy in Co3Pt layer. The perpendicular anisotropy was attributed to the existence of short-range-ordered HCP structure of Co3Pt. 相似文献
288.
289.
Nam Choul Yang Sang Min Lee Young Man Yoo Jai Kyeong Kim Dong Hack Suh 《Journal of polymer science. Part A, Polymer chemistry》2004,42(5):1058-1068
Novel polyfluorene copolymers alternately having an 1,3,4‐oxadiazole unit in the main chain were prepared by both one‐step and two‐step methods for polyoxadiazole synthesis. They displayed highly efficient blue photoluminescence, the properties of which were affected by the extent of conjugation and the changes in the electron density by a side chain. An electrochemical analysis of the polymers using cyclic voltammetry suggested that they could be used as electron‐transport/hole‐blocking materials as well as blue emission materials for polymer light‐emitting diodes. A simple double‐layer device consisting of poly(N‐vinylcarbazole) as a hole‐transport layer and poly[(9,9′‐didodecylfluorene‐2,7‐diyl)‐alt‐((1,4‐bis(1,3,4‐oxadiazole)‐2,5‐di(2‐ethylhexyloxy)phenylene)‐5,5′‐diyl)] as an emission layer exhibited narrow blue electroluminescence with a maximum at 430 nm. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 1058–1068, 2004 相似文献
290.
Huiping Shao Yuqiang Huang HyoSook Lee Yong Jae Suh Chong Oh Kim 《Journal of magnetism and magnetic materials》2006
Nontoxic cobalt acetate tetrahydrate was used as a precursor to prepare cobalt nanoparticles of 8–200 nm in average diameter by thermal decomposition. The different combinations of trioctylphosphine, oleylamine and oleic acid were added as surfactants to control the particle size. These combinations resulted in the particles with saturation magnetization and coercive force ranging from 55.0 to 100.1 emu/g and from 0 to 459.3 Oe, respectively. 相似文献