全文获取类型
收费全文 | 96362篇 |
免费 | 3750篇 |
国内免费 | 3234篇 |
专业分类
化学 | 38278篇 |
晶体学 | 1108篇 |
力学 | 7752篇 |
综合类 | 216篇 |
数学 | 33883篇 |
物理学 | 22109篇 |
出版年
2023年 | 361篇 |
2022年 | 447篇 |
2021年 | 636篇 |
2020年 | 788篇 |
2019年 | 853篇 |
2018年 | 10955篇 |
2017年 | 10787篇 |
2016年 | 6903篇 |
2015年 | 1772篇 |
2014年 | 1478篇 |
2013年 | 1873篇 |
2012年 | 5527篇 |
2011年 | 12323篇 |
2010年 | 6901篇 |
2009年 | 7323篇 |
2008年 | 7871篇 |
2007年 | 9983篇 |
2006年 | 1306篇 |
2005年 | 2232篇 |
2004年 | 2321篇 |
2003年 | 2550篇 |
2002年 | 1617篇 |
2001年 | 754篇 |
2000年 | 719篇 |
1999年 | 532篇 |
1998年 | 494篇 |
1997年 | 391篇 |
1996年 | 442篇 |
1995年 | 313篇 |
1994年 | 273篇 |
1993年 | 242篇 |
1992年 | 190篇 |
1991年 | 165篇 |
1990年 | 149篇 |
1989年 | 140篇 |
1988年 | 106篇 |
1987年 | 105篇 |
1986年 | 102篇 |
1985年 | 87篇 |
1984年 | 76篇 |
1983年 | 57篇 |
1982年 | 48篇 |
1981年 | 50篇 |
1980年 | 53篇 |
1979年 | 55篇 |
1914年 | 45篇 |
1913年 | 40篇 |
1912年 | 40篇 |
1909年 | 43篇 |
1908年 | 40篇 |
排序方式: 共有10000条查询结果,搜索用时 500 毫秒
41.
Zenon Moszner 《Aequationes Mathematicae》2018,92(4):617-625
We give the form of the output function in Ginsburg’s machine in which the input and output dictionaries are abelian groups and the transition function is of a special form. 相似文献
42.
43.
Ling-Yang Hsu Qiumin Liang Zhiheng Wang Hsin-Hung Kuo Wun-Shan Tai Shi-Jian Su Xiuwen Zhou Yi Yuan Yun Chi 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(67):15375-15386
Iridium complexes bearing chelating cyclometalates are popular choices as dopant emitters in the fabrication of organic light-emitting diodes (OLEDs). In this contribution, we report a series of blue-emitting, bis-tridentate IrIII complexes bearing chelates with two fused five-six-membered metallacycles, which are in sharp contrast to the traditional designs of tridentate chelates that form the alternative, fused five-five metallacycles. Five IrIII complexes, Px-21 – 23 , Cz-4 , and Cz-5 , have been synthesized that contain a coordinated dicarbene pincer chelate incorporating a methylene spacer and a dianionic chromophoric chelate possessing either a phenoxy or carbazolyl appendage to tune the coordination arrangement. All these tridentate chelates afford peripheral ligand–metal–ligand bite angles of 166–170°, which are larger than the typical bite angle of 153–155° observed for their five-five-coordinated tridentate counterparts, thereby leading to reduced geometrical distortion in the octahedral frameworks. Photophysical measurements and TD-DFT studies verified the inherent transition characteristics that give rise to high emission efficiency, and photodegradation experiments confirmed the improved stability in comparison with the benchmark fac-[Ir(ppy)3] in degassed toluene at room temperature. Phosphorescent OLED devices were also fabricated, among which the carbazolyl-functionalized emitter Cz-5 exhibited the best performance among all the studied bis-tridentate phosphors, showing a maximum external quantum efficiency (EQEmax) of 18.7 % and CIEx,y coordinates of (0.145, 0.218), with a slightly reduced EQE of 13.7 % at 100 cd m−2 due to efficiency roll-off. 相似文献
44.
An N. Le Ruiqi Liang Prof. Dr. Mingjiang Zhong 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(35):8177-8189
Mixed-graft block copolymers (mGBCPs) consist of two or more types of polymeric side chains grafted on a linear backbone in a random, alternating, or pseudo-alternating sequence. They can phase-separate with the backbone serving as the interface of the blocks, and the side chains dominate their self-assembly behavior. mGBCPs are an accessible polymer architecture for exploring the idea of encoding polymer properties through the macromolecular architecture, as there are two distinct structural components that can be tuned: the backbone and the side chains. In this Concept article, the current literature on the synthesis of mGBCPs is reviewed, and the advantages and disadvantages of each synthetic method are noted. The self-assembly of mGBCPs is also discussed where possible. Finally, directions for future research on mGBCP synthesis and self-assembly are suggested. 相似文献
45.
Yu Wang Xin-jing Zhao Rong-Jing Wei Gui-jie Liang Kang Wang Yuan-zhi Tan Ye Yang 《化学物理学报(中文版)》2021,34(5):591-597
The intermolecular interaction determines the photophysical properties of the organic aggregates, which are critical to the performance of organic photovoltaics. Here, excitonic coupling, an important intermolecular interaction in organic aggregates, between the π-stacking graphene quantum dots is studied by using transient absorption spectroscopy. We find that the spectral evolution of the ground state bleach arises from the dynamic variation of the excitonic coupling in the excited π-stacks. According to the spectral simulations, we demonstrate that the kinetics of the vibronic peak can be exploited as a probe to measure the dynamics of excitonic coupling in the excited π-stacks. 相似文献
46.
47.
48.
49.
The structure, chemical composition, and magnetic properties of electrochemically deposited nanocrystalline Co-Ni-Fe films
were investigated using a number of techniques. A high saturation magnetic induction up to B
s
= 21 kG was attained. An enhancement of the saturation magnetization compared to the ideal anticipated one was revealed,
which correlated with the nonlinear behavior of the structural phase composition and lattice parameters with the change of
the composition.
The text was submitted by the authors in English. 相似文献
50.
W. L. Liang B. K. A. Ngoi L. E. N. Lim K. Venkatakrishnan C. W. Hee 《Optics & Laser Technology》2003,35(4):285-290
In this paper, integration of interference phenomenon into femtosecond laser micromachining was reported as the femtosecond laser pulses were reshaped spatially to perform ablation. The generation of circular interference pattern was demonstrated by overlapping infrared femtosecond laser pulses. The interference pattern was subsequently focused on a copper substrate to ablate microstructures of concentric circular rings. The present technique is expected to open up new applications in the areas of rapid fabrication of micro-Fresnel lenses, hybrid microlenses and lens arrays. 相似文献