全文获取类型
收费全文 | 83132篇 |
免费 | 12785篇 |
国内免费 | 9583篇 |
专业分类
化学 | 44358篇 |
晶体学 | 781篇 |
力学 | 3549篇 |
综合类 | 477篇 |
数学 | 7072篇 |
物理学 | 22370篇 |
无线电 | 26893篇 |
出版年
2024年 | 199篇 |
2023年 | 1949篇 |
2022年 | 2352篇 |
2021年 | 3220篇 |
2020年 | 3282篇 |
2019年 | 3040篇 |
2018年 | 2553篇 |
2017年 | 2606篇 |
2016年 | 3606篇 |
2015年 | 3958篇 |
2014年 | 4720篇 |
2013年 | 5857篇 |
2012年 | 7049篇 |
2011年 | 7152篇 |
2010年 | 5409篇 |
2009年 | 5336篇 |
2008年 | 5697篇 |
2007年 | 5071篇 |
2006年 | 4675篇 |
2005年 | 4010篇 |
2004年 | 3075篇 |
2003年 | 2482篇 |
2002年 | 2506篇 |
2001年 | 2045篇 |
2000年 | 1760篇 |
1999年 | 1806篇 |
1998年 | 1430篇 |
1997年 | 1264篇 |
1996年 | 1244篇 |
1995年 | 1063篇 |
1994年 | 915篇 |
1993年 | 792篇 |
1992年 | 635篇 |
1991年 | 556篇 |
1990年 | 431篇 |
1989年 | 320篇 |
1988年 | 242篇 |
1987年 | 203篇 |
1986年 | 196篇 |
1985年 | 172篇 |
1984年 | 113篇 |
1983年 | 110篇 |
1982年 | 67篇 |
1981年 | 55篇 |
1980年 | 33篇 |
1979年 | 28篇 |
1977年 | 23篇 |
1976年 | 22篇 |
1975年 | 24篇 |
1972年 | 20篇 |
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
11.
Shuhai Liu Ming Han Xiaolong Feng Qiuhong Yu Long Gu Longfei Wang Yong Qin Zhong Lin Wang 《Advanced functional materials》2021,31(17):2010339
Utilizing inner-crystal piezoelectric polarization charges to control carrier transport across a metal-semiconductor or semiconductor–semiconductor interface, piezotronic effect has great potential applications in smart micro/nano-electromechanical system (MEMS/NEMS), human-machine interfacing, and nanorobotics. However, current research on piezotronics has mainly focused on systems with only one or rather limited interfaces. Here, the statistical piezotronic effect is reported in ZnO bulk composited of nanoplatelets, of which the strain/stress-induced piezo-potential at the crystals’ interfaces can effectively gate the electrical transport of ZnO bulk. It is a statistical phenomenon of piezotronic modification of large numbers of interfaces, and the crystal orientation of inner ZnO nanoplatelets strongly influence the transport property of ZnO bulk. With optimum preferred orientation of ZnO nanoplatelets, the bulk exhibits an increased conductivity with decreasing stress at a high pressure range of 200–400 MPa, which has not been observed previously in bulk. A maximum sensitivity of 1.149 µS m−1 MPa−1 and a corresponding gauge factor of 467–589 have been achieved. As a statistical phenomenon of many piezotronic interfaces modulation, the proposed statistical piezotronic effect extends the connotation of piezotronics and promotes its practical applications in intelligent sensing. 相似文献
12.
Liu Jun-Wei Shen Shu-Qian Li Ming Li Lei 《International Journal of Theoretical Physics》2021,60(5):1712-1719
International Journal of Theoretical Physics - Quantum coherence, coming from quantum superposition, occupies a significant position in the field of physics. We put forward a lower bound of the... 相似文献
13.
Journal of Optimization Theory and Applications - We distinguish two kinds of piecewise linear functions and provide an interesting representation for a piecewise linear function between two normed... 相似文献
14.
Liangtao Yang Liang-Yin Kuo Juan Miguel López del Amo Prasant Kumar Nayak Katherine A. Mazzio Sebastian Maletti Daria Mikhailova Lars Giebeler Payam Kaghazchi Teófilo Rojo Philipp Adelhelm 《Advanced functional materials》2021,31(38):2102939
A known strategy for improving the properties of layered oxide electrodes in sodium-ion batteries is the partial substitution of transition metals by Li. Herein, the role of Li as a defect and its impact on sodium storage in P2-Na0.67Mn0.6Ni0.2Li0.2O2 is discussed. In tandem with electrochemical studies, the electronic and atomic structure are studied using solid-state NMR, operando XRD, and density functional theory (DFT). For the as-synthesized material, Li is located in comparable amounts within the sodium and the transition metal oxide (TMO) layers. Desodiation leads to a redistribution of Li ions within the crystal lattice. During charging, Li ions from the Na layer first migrate to the TMO layer before reversing their course at low Na contents. There is little change in the lattice parameters during charging/discharging, indicating stabilization of the P2 structure. This leads to a solid-solution type storage mechanism (sloping voltage profile) and hence excellent cycle life with a capacity of 110 mAh g-1 after 100 cycles. In contrast, the Li-free compositions Na0.67Mn0.6Ni0.4O2 and Na0.67Mn0.8Ni0.2O2 show phase transitions and a stair-case voltage profile. The capacity is found to originate from mainly Ni3+/Ni4+ and O2-/O2-δ redox processes by DFT, although a small contribution from Mn4+/Mn5+ to the capacity cannot be excluded. 相似文献
15.
Nonlinear Dynamics - This paper proposes an optimal parameter design of control scheme for mechanical systems by adopting the Stackelberg game theory. The goal of the control is to drive the... 相似文献
16.
Xu Mengtao Li Changyou Sun Yang Yang Tianzhi Zhang Hongzhuang Liu Zhendong Liu Haiyang Li Zhenyuan Zhang Yimin 《Nonlinear dynamics》2021,105(4):3061-3092
Nonlinear Dynamics - Investigation of the dynamic characteristics of linear guideway is essential for enhancing structural performance of machine tools. However, few mechanical models are... 相似文献
17.
Journal of Visualization - The increasing availability of spatiotemporal data provides unprecedented opportunities for understanding the structure of an urban area in terms of people’s... 相似文献
18.
Mathematical Programming - In the general equilibrium with incomplete asset markets (GEI) model, the excess demand functions are typically not continuous at the prices for which the assets have... 相似文献
19.
International Journal of Theoretical Physics - The Majorana representation, which provides an intuitive way to represent the quantum state by stars on the Bloch sphere, has drawn considerable... 相似文献
20.
Telecommunication Systems - Machine to Machine technology has a broad application prospect in the 5G network, but there is a bottleneck in the energy consumption of intelligent devices powered by... 相似文献