全文获取类型
收费全文 | 9627篇 |
免费 | 1814篇 |
国内免费 | 1068篇 |
专业分类
化学 | 6790篇 |
晶体学 | 89篇 |
力学 | 593篇 |
综合类 | 60篇 |
数学 | 1109篇 |
物理学 | 3868篇 |
出版年
2024年 | 10篇 |
2023年 | 228篇 |
2022年 | 227篇 |
2021年 | 361篇 |
2020年 | 419篇 |
2019年 | 384篇 |
2018年 | 370篇 |
2017年 | 300篇 |
2016年 | 532篇 |
2015年 | 455篇 |
2014年 | 584篇 |
2013年 | 768篇 |
2012年 | 942篇 |
2011年 | 928篇 |
2010年 | 637篇 |
2009年 | 622篇 |
2008年 | 634篇 |
2007年 | 546篇 |
2006年 | 501篇 |
2005年 | 410篇 |
2004年 | 316篇 |
2003年 | 243篇 |
2002年 | 194篇 |
2001年 | 164篇 |
2000年 | 183篇 |
1999年 | 216篇 |
1998年 | 170篇 |
1997年 | 161篇 |
1996年 | 182篇 |
1995年 | 146篇 |
1994年 | 121篇 |
1993年 | 90篇 |
1992年 | 100篇 |
1991年 | 56篇 |
1990年 | 73篇 |
1989年 | 54篇 |
1988年 | 26篇 |
1987年 | 28篇 |
1986年 | 37篇 |
1985年 | 38篇 |
1984年 | 14篇 |
1983年 | 16篇 |
1982年 | 6篇 |
1981年 | 4篇 |
1980年 | 6篇 |
1979年 | 2篇 |
1977年 | 1篇 |
1976年 | 2篇 |
1957年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 78 毫秒
1.
Science China Chemistry - 相似文献
2.
Qiang Chenxu Hao Yuxin Zhang Wei Li Jinqiang Yang Shaowu Cao Yuteng 《应用数学和力学(英文版)》2021,42(11):1555-1570
Applied Mathematics and Mechanics - The concept of local resonance phononic crystals proposed in recent years provides a new chance for theoretical and technical breakthroughs in the structural... 相似文献
3.
Jiang Rui-Yang Xin Jia-Wei Cao Cong 《International Journal of Theoretical Physics》2021,60(8):2836-2855
International Journal of Theoretical Physics - Quantum logic gates are the foundation of circuit-based quantum computation and quantum simulation. Multi-qubit quantum controlled gates are of vital... 相似文献
4.
In this paper, we present and analyze an energy-conserving and linearly implicit scheme for solving the nonlinear wave equations. Optimal error estimates in time and superconvergent error estimates in space are established without certain time-step restrictions. The key is to estimate directly the solution bounds in the H2-norm for both the nonlinear wave equation and the corresponding fully discrete scheme, while the previous investigations rely on the temporal-spatial error splitting approach. Numerical examples are presented to confirm energy-conserving properties, unconditional convergence and optimal error estimates, respectively, of the proposed fully discrete schemes.
相似文献5.
本文用水热法制备了正交晶系的纳米球状结构的二氧化锡和正交晶系的由片状聚集成球状结构的钨酸铋,并且对二者进行了复合,制备出了二氧化锡/钨酸铋复合光催化材料。采用X射线衍射(XRD)、扫描电子显微镜(SEM)、比表面积测试仪(BET)、紫外可见分光光度计等技术对复合样品的结构、形貌、比表面积、孔容孔径和光学性质进行了表征。用碘钨灯模拟太阳光,分别以二氧化锡、钨酸铋和二氧化锡/钨酸铋复合材料为催化剂降解罗丹明B(RhB),研究所制备的二氧化锡/钨酸铋复合材料的光催化活性。光催化90 min时二氧化锡、钨酸铋和二氧化锡/钨酸铋对罗丹明B的降解率分别是9%、22%和30%。实验结果表明,在可见光下,二氧化锡/钨酸铋复合材料的光催化活性要高于单一的二氧化锡和钨酸铋。 相似文献
6.
Since most of the control strategies for air-breathing hypersonic vehicles (AHVs) concentrate on the control-oriented models built at/around a specific working point, it is somewhat hard to extend them to the broader flight envelop. Aiming at the above deficiency, this paper formulates the dynamics of AHVs as several sub-models, which switch to each other in accordance with the flight condition and make up of the control-oriented switched model (COSM). With the aid of the COSM, two adaptive tracking controllers are proposed for the purposes of velocity tracking and altitude tracking, sequentially. By utilizing neural networks and designing robust control laws, the possible changes on the force and moment coefficients in the COSM are successfully handled. The time-varying inertia parameters of AHVs are also considered at design level. It is worth emphasizing that while this strategy is developed based on a switched model, the resulting control algorithm is continuous with no connection to the switching signal. Analysis indicates that both velocity and altitude tracking errors remain small within the whole flight envelop, which is further confirmed by a simulation study. 相似文献
7.
Fei Zhang GaoShan Huang XiaoFei Nie Xin Cao Zhe Ma Fei Ding ZengFeng Di HongLou Zhen YongFeng Mei 《Physics letters. A》2019,383(24):2938-2942
In this study, we investigate the modulation of energy band in 3D self-assembled nanomembranes containing GaAs/Al0.26Ga0.74As quantum wells (QWs). Photoluminescence (PL) characterizations demonstrate that the self-assembled structures have different optical transition properties and the modulation of the energy band is thus realized. Detailed spectral analyses disclose that the small strain change in structures with different curvatures cannot cause remarkable change in energy bands in Al0.26Ga0.74As layer. On the other hand, the optical transitions of GaAs QW layer is influenced by the strain evolution in term of light emission intensity. We also find the first order Stark effect in rolled-up nanomembrane with diameter of 150 μm, which is closely connected with the coupling effect between the deformation potential and the piezoelectric potential. Our work may pave a way for the fabrication of high performance rolled-QW infrared photo-detectors. 相似文献
8.
9.
Herein we summarized some clean preparation examples to emphasize the concept of dual roles design (or named as “two birds one stone strategy”) in green and sustainable chemistry. In those examples, the reactants and/or solvent play dual roles rendering a cleaner organic preparation process. Consequently, both the chemical waste and manufacturing cost could be reduced. 相似文献
10.