全文获取类型
收费全文 | 1669篇 |
免费 | 364篇 |
国内免费 | 215篇 |
专业分类
化学 | 822篇 |
晶体学 | 32篇 |
力学 | 150篇 |
综合类 | 35篇 |
数学 | 58篇 |
物理学 | 1151篇 |
出版年
2024年 | 5篇 |
2023年 | 18篇 |
2022年 | 75篇 |
2021年 | 71篇 |
2020年 | 91篇 |
2019年 | 49篇 |
2018年 | 51篇 |
2017年 | 85篇 |
2016年 | 104篇 |
2015年 | 93篇 |
2014年 | 124篇 |
2013年 | 141篇 |
2012年 | 101篇 |
2011年 | 138篇 |
2010年 | 100篇 |
2009年 | 110篇 |
2008年 | 88篇 |
2007年 | 98篇 |
2006年 | 100篇 |
2005年 | 81篇 |
2004年 | 73篇 |
2003年 | 73篇 |
2002年 | 55篇 |
2001年 | 37篇 |
2000年 | 46篇 |
1999年 | 31篇 |
1998年 | 26篇 |
1997年 | 30篇 |
1996年 | 32篇 |
1995年 | 22篇 |
1994年 | 14篇 |
1993年 | 17篇 |
1992年 | 17篇 |
1991年 | 9篇 |
1990年 | 8篇 |
1989年 | 5篇 |
1988年 | 6篇 |
1987年 | 2篇 |
1986年 | 2篇 |
1985年 | 5篇 |
1984年 | 2篇 |
1982年 | 4篇 |
1980年 | 3篇 |
1979年 | 5篇 |
1975年 | 1篇 |
排序方式: 共有2248条查询结果,搜索用时 31 毫秒
141.
Zhijie Gu Tatsuya Kanto Kousuke Tsuchiya Takeshi Shimomura Kenji Ogino 《Journal of polymer science. Part A, Polymer chemistry》2011,49(12):2645-2652
Novel block copolymers, poly(3‐hexylthiophene)‐b‐poly(ethylene oxide) (P3HT‐b‐PEO) were synthesized via Suzuki coupling reaction of P3HT and PEO homopolymers. The copolymers were characterized by NMR, gel permeation chromatography, differential scanning calorimeter, and UV–vis measurements. A series of devices based on the block copolymers with a fullerene derivative were evaluated after thermal or solvent annealing. The device using P3HT‐b‐PEO showed higher efficiency than using P3HT blend after thermal annealing. Phase‐separated structures in the thin films of block copolymer blends were investigated by atomic force microscopy to clarify the relationship between morphologies constructed by annealing and the device performance. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011 相似文献
142.
Lin Ke Shuang Fang Lim Soo Jin Chua 《Journal of Polymer Science.Polymer Physics》2001,39(14):1697-1703
Dark spot growth rate tracing experiments performed on an organic light‐emitting device show that moisture entering into the device is relatively properly fitted by Fick's diffusion equation in the substrate/indium tin oxide (ITO)/hole transport layer (HTL)/silver (Ag) structure. It is believed that the moisture is dissolved into the polymer layer, which results in a decrease in the diffusion coefficient in the device with the substrate/ITO/HTL/electroluminescent (EL) polymer/Ag structure. The diffusion and chemical reaction occurring in the cathode layer further decreases the diffusion coefficient in the device with the substrate/ITO/HTL/EL polymer/calcium/Ag structure. Useful parameters, such as diffusion and solubility constants, describing possible mechanisms happening during dark spot growth on organic light‐emitting diode devices are extracted. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 39: 1697–1703, 2001 相似文献
143.
Successful demonstration of selective area doping of planar glass samples for monolithic integration of optically passive and active devices on a single chip is presented. Salt solution of erbium was delivered onto pre-sintered germano-silicate samples via a syringe. The samples were then consolidated to form dense glass layers containing regions doped with rare earth. Erbium tri-chloride solution, 0.1 M, was used during the solution doping phase, with the resulting erbium atomic percentage ranging from more than 0.1-0.4%, increasing linearly with the number of drips applied. 相似文献
144.
A sub-micron hydrophilic microchannel was fabricated on poly(dimethylsiloxane) (PDMS) in one step using vacuum ultraviolet light (VUV) lithography in vacuum. The topographies and properties of the irradiated PDMS surface were characterized and analyzed by atomic force microscopy (AFM), and the chemical composition changes on VUV-treated PDMS analyzed by X-ray photoelectron spectroscopy (XPS). The hydrophilic stability of irradiated PDMS surface was studied by static water contact angle. As demonstrated, the hydrophilicity on surface of PDMS microchannel can be kept for a longer term even three months after the treatment. 相似文献
145.
G.P. Pepe G. Peluso R. Scaldaferri L. Parlato C. Granata E. Esposito M. Russo 《The European Physical Journal B - Condensed Matter and Complex Systems》2001,23(4):421-425
A new fabrication process for three-terminal superconducting devices consisting of two Josephson junctions in a stacked configuration
is reported. The process is based on the deposition of the whole Nb/AlxOy/Nb-Al/AlxOy/Nb multilayer on a Si crystalline wafer without any vacuum breaking. Lift-off techniques, anodization processes and a SiO
film deposition have been adopted for patterning and insulating the two tunnel stacked junctions. Devices have been characterized
in terms of current-voltage (I-V) curves and Josephson critical current vs. the externally applied magnetic field. They show high quality factors (V
m values up to 65 mV at 4.2 K), and good current uniformity.
Received 5 June 2001 相似文献
146.
147.
研制半自动定容试液,半自动定位恒速注入KBK4,整个氢化过程不串空气,可用压力全方位喷射冲洗反应室。该装置定容定位准确,操作简便快速,适用于大批量样品分析。通过对8个GSD标准参考物质的分析,分析结果与参考值基本一致,RSD<6%。 相似文献
148.
Improving the specularity of magnetic mirrors for atoms 总被引:1,自引:0,他引:1
G. Zabow M. Drndić J.H. Thywissen K.S. Johnson R.M. Westervelt M. Prentiss 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》1999,7(3):351-359
An array of anti-parallel current-carrying wires creates an inhomogeneous magnetic field capable of reflecting neutral atoms.
We present analytical and numerical analyses of the magnetic field produced by such an array, and describe methods for reducing
the resulting rms angular deviation from specular reflection to less than 0.1 mrad. Careful choice of cross-sectional wire
profiles is shown to dramatically improve specularity of reflection close to the surface. Additionally, we find that the specularity
depends on whether the number of wires in the mirror is even or odd, and that there exists an optimal turning height above
the surface that maximizes the specularity of reflection from the mirror.
Received 16 November 1998 相似文献
149.
150.
An Accurate Characterization of CRT Monitor (I) Verifications of Past Studies and Clarifications of Gamma 总被引:1,自引:0,他引:1
CRT monitors are widely used to view images on the Internet. The color images on the computer graphic display can be printed out or displayed on other monitors through the Internet, and color matching between the original and the reproduction is very important. The color management systems (CMSs) are useful for the color matching. CMSs utilize device profiles, in which color characteristic information is stored, and these profiles are generated by device characterization. Thus, an accurate characterization of the monitor is essential for better color matching. CRT monitor characteristics can be described by the tone reproduction curves (TRCs) of each channel, and color additive matrix. In this paper, these characteristics were investigated from a physical point of view. Various kinds of flare and the interdependence among the channels were also investigated and verified. The definition of the term “gamma” is clarified, which is very often used to describe the TRC. Various definitions are compared and a new definition of S-γ is proposed. 相似文献