全文获取类型
收费全文 | 30249篇 |
免费 | 5064篇 |
国内免费 | 4051篇 |
专业分类
化学 | 21618篇 |
晶体学 | 300篇 |
力学 | 1864篇 |
综合类 | 316篇 |
数学 | 3670篇 |
物理学 | 11596篇 |
出版年
2024年 | 11篇 |
2023年 | 552篇 |
2022年 | 592篇 |
2021年 | 846篇 |
2020年 | 1156篇 |
2019年 | 1187篇 |
2018年 | 1021篇 |
2017年 | 977篇 |
2016年 | 1333篇 |
2015年 | 1368篇 |
2014年 | 1789篇 |
2013年 | 2267篇 |
2012年 | 2649篇 |
2011年 | 2769篇 |
2010年 | 2047篇 |
2009年 | 2009篇 |
2008年 | 2214篇 |
2007年 | 2030篇 |
2006年 | 1924篇 |
2005年 | 1682篇 |
2004年 | 1287篇 |
2003年 | 1046篇 |
2002年 | 1092篇 |
2001年 | 817篇 |
2000年 | 702篇 |
1999年 | 650篇 |
1998年 | 496篇 |
1997年 | 450篇 |
1996年 | 412篇 |
1995年 | 340篇 |
1994年 | 287篇 |
1993年 | 247篇 |
1992年 | 200篇 |
1991年 | 172篇 |
1990年 | 182篇 |
1989年 | 136篇 |
1988年 | 92篇 |
1987年 | 46篇 |
1986年 | 53篇 |
1985年 | 52篇 |
1984年 | 24篇 |
1983年 | 34篇 |
1982年 | 30篇 |
1981年 | 19篇 |
1980年 | 15篇 |
1979年 | 7篇 |
1978年 | 14篇 |
1977年 | 6篇 |
1976年 | 4篇 |
1916年 | 3篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
本文采用第一性原理方法,在100 GPa的压力范围内,计算了GeO_2理想晶体和含锗、氧空位点缺陷晶体的光学性质.吸收谱数据表明,压力诱导的三个结构相变对GeO_2晶体的吸收谱均有影响:第一个相变将导致其吸收边蓝移,而第二和第三相变将使得其吸收边红移.锗和氧空位点缺陷的存在将导致GeO_2的吸收边红移,但氧空位点缺陷引起的红移更明显.尽管如此,分析发现,在100 GPa的压力范围内,压力、相变以及空位点缺陷等因素都不会导致GeO_2晶体在可见光区出现光吸收现象(是透明的).波长在532 nm处的折射率数据显示,在GeO_2的四个相区,其折射率均随压力增加而降低;而且,GeO_2的三个结构相变以及锗、氧空位点缺陷都会导致其折射率有所增大.本文预测,GeO_2有成为冲击光学窗口材料的可能. 相似文献
2.
In this paper, we study the relations of the sizes of various sections of finite linear groups and the largest orbit size of the linear group actions. We also study various applications of those orbit theorems. 相似文献
3.
4.
Despite some empirical successes for solving nonlinear evolution equations using deep learning,there are several unresolved issues.First,it could not uncover the dynamical behaviors of some equations where highly nonlinear source terms are included very well.Second,the gradient exploding and vanishing problems often occur for the traditional feedforward neural networks.In this paper,we propose a new architecture that combines the deep residual neural network with some underlying physical laws.Using the sine-Gordon equation as an example,we show that the numerical result is in good agreement with the exact soliton solution.In addition,a lot of numerical experiments show that the model is robust under small perturbations to a certain extent. 相似文献
5.
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
6.
Applications of Mathematics - We prove a regularity criterion for a nonhomogeneous incompressible Ginzburg-Landau-Navier-Stokes system with the Coulomb gauge in ?3. It is proved that if the... 相似文献
7.
Yuan Zhou Dong-Yan Lü Guang-Hui Wang Yan-Hua Fu Ming-Yao He Hong-Tao Ren 《理论物理通讯》2021,73(6):65101
It remains a great challenge to realize direct manipulation of a nitrogen-vacancy(NV) spin at the single-quantum level with a microwave(MW) cavity. As an alternative, a hybrid system with the spin–phonon–photon triple interactions mediated by a squeezed cantilever-type harmonic resonator is proposed. According to the general mechanical parametric amplification of this in-between phonon mode, the direct spin–phonon and photon–phonon couplings are both exponentially enhanced, which can even further improve the coherent manipulation of a single NV spin and MW photon with a higher efficiency. In view of this triple system with enhanced couplings and the additional sideband adjustable designs, this scheme may provide a more efficient phonon-mediated platform to bridge or manipulate the MW quantum and a single electron spin coherently. It is also hoped to evoke wider applications in the areas of quantum state transfer and preparation,ultrasensitive detection and quantum nondestructive measurement, etc. 相似文献
8.
随着电力计量业务的不断扩展,迫切需要由业务信息、技术知识、行业标准及其内在联系所组成的电力计量知识图谱,为电网的决策和发展提供更为全面有效的支持。命名实体识别是构建知识图谱的基础。针对电力计量领域需要,结合中文分词技术特点,基于联合学习思想,提出了一种基于联合学习的中文电力计量命名实体识别技术。该技术联合CNN-BLSTM-CRF模型与整合词典知识的分词模型,使其共享实体类别和置信度;同时将2个模型的先后计算顺序改为并行计算,减少了识别误差累积。结果表明,在不需要人工构建特征的情况下,方法的正确率、召回率、F 值等均显著优于以往方法。 相似文献
9.
Yong Quan HU 《数学学报(英文版)》2021,37(1):59-72
In the p-adic local Langlands correspondence for GL_2(Q_p), the following theorem of Berger and Breuil has played an important role: the locally algebraic representations of GL_2(Q_p) associated to crystabelline Galois representations admit a unique unitary completion. In this note, we give a new proof of the weaker statement that the locally algebraic representations admit at most one unitary completion and such a completion is automatically admissible. Our proof is purely representation theoretic, involving neither(ψ, Γ)-module techniques nor global methods. When F is a finite extension of Q_p, we also get a simpler proof of a theorem of Vignéras for the existence of integral structures for(locally algebraic) special series and for(smooth) tamely ramified principal series. 相似文献
10.
A numerical model was developed and validated to investigate the fluid–structure interactions between fully developed pipe flow and core–shell-structured microcapsule in a microchannel. Different flow rates and microcapsule shell thicknesses were considered. A sixth-order rotational symmetric distribution of von Mises stress over the microcapsule shell can be observed on the microcapsule with a thinner shell configuration, especially at higher flow rate conditions. It is also observed that when being carried along in a fully developed pipe flow, the microcapsule with a thinner shell tends to accumulate stress at a higher rate compared to that with a thicker shell. In general, for the same microcapsule configuration, higher flow velocity would induce a higher stress level over the microcapsule shell. The deformation gradient was used to capture the microcapsule's deformation in the present study. The effect of Young's modulus on the microcapsule shell on the microcapsule deformation was investigated as well. Our findings will shed light on the understanding of the stability of core–shell-structured microcapsule when subjected to flow-induced shear stress in a microfluidic system, enabling a more exquisite control over the breakup dynamics of drug-loaded microcapsule for biomedical applications. 相似文献