全文获取类型
收费全文 | 17413篇 |
免费 | 3118篇 |
国内免费 | 2217篇 |
专业分类
化学 | 12925篇 |
晶体学 | 182篇 |
力学 | 1064篇 |
综合类 | 138篇 |
数学 | 2230篇 |
物理学 | 6209篇 |
出版年
2024年 | 46篇 |
2023年 | 308篇 |
2022年 | 548篇 |
2021年 | 636篇 |
2020年 | 710篇 |
2019年 | 689篇 |
2018年 | 591篇 |
2017年 | 541篇 |
2016年 | 869篇 |
2015年 | 983篇 |
2014年 | 1028篇 |
2013年 | 1287篇 |
2012年 | 1547篇 |
2011年 | 1580篇 |
2010年 | 1154篇 |
2009年 | 1078篇 |
2008年 | 1160篇 |
2007年 | 999篇 |
2006年 | 917篇 |
2005年 | 774篇 |
2004年 | 693篇 |
2003年 | 560篇 |
2002年 | 697篇 |
2001年 | 539篇 |
2000年 | 399篇 |
1999年 | 363篇 |
1998年 | 314篇 |
1997年 | 273篇 |
1996年 | 242篇 |
1995年 | 218篇 |
1994年 | 184篇 |
1993年 | 165篇 |
1992年 | 123篇 |
1991年 | 117篇 |
1990年 | 92篇 |
1989年 | 60篇 |
1988年 | 53篇 |
1987年 | 47篇 |
1986年 | 21篇 |
1985年 | 32篇 |
1984年 | 24篇 |
1983年 | 17篇 |
1982年 | 8篇 |
1981年 | 19篇 |
1980年 | 7篇 |
1979年 | 8篇 |
1978年 | 4篇 |
1976年 | 3篇 |
1974年 | 5篇 |
1936年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 33 毫秒
71.
Xiaoming Wu Yulin Hua Zhaoqi Wang Jiajin Zheng Shougen Yin Jiachun Deng Kongwu Wu Songliu Feijian Zhu Xia Niu 《Optik》2006,117(8):373-376
A bright white organic light-emitting diode (OLED) has been successfully fabricated in which a greenish-white emitting host Bis-(2-(2-hydroxyphenyl) benzothiazole)zinc (Zn(BTZ)2) is doped with an orange-red fluorescent dye 5,6,11,12-tetraphenylnaphthacene (rubrene). The pure white light emission with CIE coordinates of (0.341, 0.334) is achieved at the driving voltage of 20 V, and the corresponding luminance and external quantum efficiency are 4000 Cd/m2 and 0.63%. On the other hand, the pure red, green, and blue (RGB) emissions are obtained from the white OLED combined well with RGB custom-built optical color filters (CFs) with peaks at 616, 556, and 456 nm, respectively. Moreover, based upon the color mixture principles, we build a model of multi-color display mixed by the pure RGB emissions under the controllable bias. 相似文献
72.
JIANG Wei-na YANG Shi-long LU Wen XU Li TANG Ying XUE Hua-yu GAO Bu-hong DU Li-ting SUN Hai-jun MA Meng-tao XU Hai-jun CAO Fu-liang 《光谱学与光谱分析》2018,38(8):2650-2656
制备了一种基于天然产物槲皮素接枝硅包银核壳结构的纳米荧光传感器(Ag@SiO2@Qc),对铜离子具有好的选择性和灵敏性。Ag@SiO2@Qc与Cu2+离子结合后,荧光发射强度发生猝灭,并且可通过荧光滴定光谱得到了荧光滴定曲线:y = -32.864x+587.59(R2=0.998),其线性范围分别为:3×10-7~4.8×10-6 mol·L-1,最低检测限为1.0×10-7 mol·L-1。并且将Ag@SiO2@Qc应用于环境中水样的检测结果的准确度好,精密度高,而且更加环保、方便、快捷,具有很大发展潜力与应用价值。 相似文献
73.
74.
Recent measurements of charge-dependent azimuthal correlations in high-energy heavy-ion collisions have indicated charge-separation signals perpendicular to the reaction plane, and have been related to the chiral magnetic effect(CME). However, the correlation signal is contaminated with the background caused by the collective motion(flow) of the collision system, and an effective approach is needed to remove the flow background from the correlation. We present a method study with simplified Monte Carlo simulations and a multi-phase transport model,and develop a scheme to reveal the true CME signal via event-shape engineering with the flow vector of the particles of interest. 相似文献
75.
A novel MI-insensitive and filterless frequency octupling scheme based on two parallel dual-parallel Mach–Zehnder modulators (DP-MZMs) is proposed. The proposed scheme is not sensitive to modulation index and relatively strong MMW signal with good radio frequency spurious suppression ratio (RFSSR) can be obtained without strict requirement on modulation index. Filterless feature makes the scheme quite suitable for wavelength division multiplexing (WDM) applications. For verification, a 60 GHz millimeter wave with 44 dB RFSSR is generated from a 7.5 GHz radio frequency wave by simulation. Performance of the proposed scheme has been characterized under different conditions including DC-bias drifts of MZMs, different amplitudes of RF inputs and different extinction ratios of MZMs. 相似文献
76.
77.
Applications for piezoelectric efect have grown rapidly,and piezoelectric materials play important roles in countless areas of modern life.By means of twoscale method and coupled boundary layer,some new kinds of twoscale asymptotic expansions for solutions to the electrical potential and the displacement in quasi-periodic structure under coupled piezoelectric efect are derived,and the homogenization constants of piezoelectric materials are presented.The coupled twoscale relation between the electrical potential and the displacement is set up,and some improved asymptotic error estimates are analyzed. 相似文献
78.
Solitons and intrinsic localized modes in a one-dimensional antiferromagnetic chain 总被引:3,自引:0,他引:3 下载免费PDF全文
By use of the Hartree approximation and the method of multiple scales, we
investigate quantum solitons and intrinsic localized modes in a
one-dimensional antiferromagnetic chain. It is shown that there exist
solitons of two different quantum frequency bands: i.e., magnetic optical
solitons and acoustic solitons. At the boundary of the Brillouin zone, these
solitons become quantum intrinsic localized modes: their quantum
eigenfrequencies are below the bottom of the harmonic optical frequency band
and above the top of the harmonic acoustic frequency band. 相似文献
79.
This paper proposes a scheme for teleporting a kind of essential three-particle
non-symmetric entangled state, which is much more valuable than a GHZ and W state
for some applications in quantum information processing. In comparison with previous
proposal of teleportation, the resources of entangled states as quantum channel and
the number of classical messages required by our scheme can be cut down. Moreover,
it is shown that there exists a class of transformations which ensure the success of
this scheme, because the two-particle transformation performed by the receiver in
the course of teleportation may be a generic two-particle operation instead of a
control-NOT (CNOT) operation. In addition, all kinds of transformations performed by
sender and receiver are given in detail. 相似文献
80.
宽频带激光自由空间传输的调制特性研究 总被引:9,自引:0,他引:9
基于惠更斯-菲涅耳衍射积分公式,研究了宽带光束在菲涅耳衍射区的自由空间传输特性,得到宽带光束传输的调制深度与光束带宽Δλ及菲涅耳数F的变化关系。结果表明:一定的带宽对光束的均匀性有适当的改善;当光束的带宽Δλ<2λ0/F时,带宽越大,光束越均匀;当带宽满足条件Δλ=2λ0/F时,菲涅耳衍射完全消失;在一定的菲涅耳数范围内,宽带光束的调制深度随菲涅耳数振荡变化,振荡曲线的主极大值和次极大值分别出现在菲涅耳数为奇数和偶数处,而极小值则出现在菲涅耳数F=2k±1/3(k=1,2,3,…)处,在极小值处光束的均匀性最好。 相似文献