全文获取类型
收费全文 | 30198篇 |
免费 | 4064篇 |
国内免费 | 2725篇 |
专业分类
化学 | 20546篇 |
晶体学 | 284篇 |
力学 | 1947篇 |
综合类 | 274篇 |
数学 | 3292篇 |
物理学 | 10644篇 |
出版年
2024年 | 105篇 |
2023年 | 589篇 |
2022年 | 911篇 |
2021年 | 1015篇 |
2020年 | 1116篇 |
2019年 | 1087篇 |
2018年 | 912篇 |
2017年 | 815篇 |
2016年 | 1282篇 |
2015年 | 1269篇 |
2014年 | 1537篇 |
2013年 | 2051篇 |
2012年 | 2635篇 |
2011年 | 2659篇 |
2010年 | 1648篇 |
2009年 | 1634篇 |
2008年 | 1738篇 |
2007年 | 1662篇 |
2006年 | 1490篇 |
2005年 | 1230篇 |
2004年 | 941篇 |
2003年 | 792篇 |
2002年 | 754篇 |
2001年 | 565篇 |
2000年 | 559篇 |
1999年 | 654篇 |
1998年 | 578篇 |
1997年 | 575篇 |
1996年 | 664篇 |
1995年 | 512篇 |
1994年 | 465篇 |
1993年 | 391篇 |
1992年 | 372篇 |
1991年 | 322篇 |
1990年 | 257篇 |
1989年 | 202篇 |
1988年 | 158篇 |
1987年 | 139篇 |
1986年 | 127篇 |
1985年 | 118篇 |
1984年 | 88篇 |
1983年 | 61篇 |
1982年 | 41篇 |
1981年 | 36篇 |
1980年 | 18篇 |
1978年 | 19篇 |
1977年 | 23篇 |
1976年 | 20篇 |
1975年 | 28篇 |
1974年 | 27篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
971.
Wei Huang Jie-Min Li Li-Mei Yang Zhong-Liang Jin Zheng-Gen Zhong Yu Liu Qin-Ying Chou Feng Li 《Optics & Laser Technology》2011,43(1):214-217
A 32 in RGB LED backlight unit is developed. A local dimming algorithm is designed for the backlight, and grid-noise artifacts in the LC driving signal are successfully removed with consideration of the backlight distribution to provide identical intensity from each LED block. The 32 in RGB LED backlight LCD display has achieved a static display contrast of over 20000:1 and an average power reduction of 30%. We have also obtained the color gamut transformation matrix for transferring a cold cathode fluorescent lamp BLU LCD display gamut system to our RGB LED BLU LCD display gamut system, and extended the color saturation by suppositional color expansion method. As a result, the color has been accurately reproduced in RGB LED BLU LCD display with more richness and more saturation. 相似文献
972.
973.
智能交通系统可以实时反馈路况信息、诱导出行,进而缓解交通拥堵.在时间反馈和平均速度反馈两种信息服务策略下,考虑重叠路段的影响,利用元胞自动机模型对人们的路径选择行为进行了模拟.结果表明,在含有重叠路段的网络中,相对时间反馈策略而言,平均速度反馈策略可以更有效地降低人们的出行时间,其优势在重叠部分长度占路径长度的比例很小和较大时十分明显,且随路径长度的增加而上升.在提高路网的利用效率方面,平均速度反馈策略的优势随路径长度的增加而逐渐下降,随重叠部分长度的增加而先降后升.
关键词:
交通流
元胞自动机
智能交通系统
信息反馈策略 相似文献
974.
Guang-Yong Zhou Lin-Jian Huang Jun-Ya Pan Li-Yun Hu Jie-Hui Huang 《Frontiers of Physics》2018,13(4):130701
Resource theory is applied to quantify the quantum correlation of a bipartite state and a computable measure is proposed. Since this measure is based on quantum coherence, we present another possible physical meaning for quantum correlation, i.e., the minimum quantum coherence achieved under local unitary transformations. This measure satisfies the basic requirements for quantifying quantum correlation and coincides with concurrence for pure states. Since no optimization is involved in the final definition, this measure is easy to compute irrespective of the Hilbert space dimension of the bipartite state. 相似文献
975.
976.
Duan Yan-min Li Ai-hong Chen Jing Zhu Hai-yong Zhang Ge Huang Cheng-hui Wei Yong Huang Ling-xiong Qiu Yi-shen 《Journal of Russian Laser Research》2008,29(3):268-273
We report an LD-end-pumped linearly-polarized continuous-wave (CW) Nd:YAP laser operating at 1341.4 nm. Making use of the
plane-concave resonator (T = 2.4%) and the plane-plane resonator (T = 2.6%), we obtain linearly-polarized laser radiation at 1341.4 nm with a power of 3.15 and 2.86 W and corresponding optical
slope efficiency of 18.4 and 17.5%, respectively. The effect of the laser oscillation mode on the output is analyzed. An experiment
on the intra-cavity frequency doubling with an LBO crystal has been performed, and a laser power of 431 mW in one direction
at 670.7 nm was obtained. 相似文献
977.
M. K. Hossain Y. Kitahama G. G. Huang T. Kaneko Y. Ozaki 《Applied physics. B, Lasers and optics》2008,93(1):165-170
In this study, surface plasmon resonance (SPR) and surface-enhanced Raman scattering (SERS) characteristics of gold nanoaggregates
with different morphologies are examined to elucidate the correlation between SPR and SERS of the object. Nanoaggregates,
defined as random aggregates (hereafter RA), elongated aggregates (hereafter EA) and two-dimensional layered aggregates (hereafter
2DLA) are fabricated by immobilizing colloidal gold nanoparticles on glass substrates. The color variation observed in the
RA and EA samples indicates the variation in localized SPR excitations excited on the samples. The RA sample mostly shows
a broadened and shifted SPR peak centered at 570 nm in addition to another peak in the longer wavelength region (∼700 nm),
whereas in the EA sample a weak blue-shifted peak is observed near 450 nm in addition to a broadened peak centered at 570 nm
covering a trail for another one near 700 nm. In the case of the 2DLA sample, more than one SPR peaks are observed in the
longer wavelength region. The SERS observation confirms million times higher enhancement at least in Raman intensity using
the gold nanoaggregates adsorbed by dye molecules. The EA sample of gold nanoparticles shows ∼5 times higher enhancement in
Raman signal compared to that of the RA and 2DLA sample. 相似文献
978.
Xiao-jie Yi Yi-You Nie Nan-run Zhou Yi-bing Huang Zhi-hui Hong 《International Journal of Theoretical Physics》2008,47(12):3401-3407
We propose a quantum secure direct communication scheme based on non-orthogonal entangled pairs and local measurement. In
this scheme, we use eight non-orthogonal entangled pairs to act as quantum channels. Due to the non-orthogonality of the quantum
channels, the present protocol can availably prohibit from all kinds of valid eavesdropping and acquire a secure quantum channel.
By local measurement, the sender acquires a secret random sequence. The process of encoding on the random sequence is identical
to the one in one-time-pad. So the present protocol is secure. Even for a highly lossy channel, our scheme is also valid.
The scheme is feasible with present-day techniques. 相似文献
979.
Coupling a single-mode laser diode with 200 mW to a single-mode fiber (SMF) through an orthonormal aspherical cylindrical lens and a GRIN lens for the intersatellite optical communication system is proposed and demonstrated. We experimentally studied how the coupling efficiency changes with the SMF's position displacement and axial angle variation, and obtained 80 mW output power at the end of the SMF, which shows that the coupling units have satisfied the designed request. 相似文献
980.
In the present study, bovine serum albumin (BSA) was successfully covalently immobilized on the surface of anatase TiO2 film by a three-step method, i.e. application of H3PO4 chemisorption to increase surface -OH, which increases the amount of coupling 3-aminopropyl-triethoxylsilane (APTES), thus linking with BSA by imide bond using EDC/NHS/MES. There is no significant -OH group increase on rutile film when using the same method of phosphoric acid treatment, which suggest it is difficult for further chemical modification of the rutile film. After covalent immobilization of BSA on anatase film, an improved hemocompatibility of anti-platelet adhesion and aggregation in vitro could be recognized by LDH and SEM analysis. This study suggests BSA-immobilized anatase surface can serve as hemocompatibility material in vivo. 相似文献