全文获取类型
收费全文 | 24548篇 |
免费 | 3892篇 |
国内免费 | 2723篇 |
专业分类
化学 | 17338篇 |
晶体学 | 302篇 |
力学 | 1486篇 |
综合类 | 251篇 |
数学 | 2736篇 |
物理学 | 9050篇 |
出版年
2024年 | 46篇 |
2023年 | 502篇 |
2022年 | 831篇 |
2021年 | 814篇 |
2020年 | 1016篇 |
2019年 | 927篇 |
2018年 | 761篇 |
2017年 | 732篇 |
2016年 | 1107篇 |
2015年 | 1032篇 |
2014年 | 1280篇 |
2013年 | 1670篇 |
2012年 | 2117篇 |
2011年 | 2125篇 |
2010年 | 1455篇 |
2009年 | 1401篇 |
2008年 | 1569篇 |
2007年 | 1424篇 |
2006年 | 1375篇 |
2005年 | 1118篇 |
2004年 | 889篇 |
2003年 | 737篇 |
2002年 | 641篇 |
2001年 | 535篇 |
2000年 | 527篇 |
1999年 | 617篇 |
1998年 | 503篇 |
1997年 | 437篇 |
1996年 | 443篇 |
1995年 | 399篇 |
1994年 | 363篇 |
1993年 | 332篇 |
1992年 | 277篇 |
1991年 | 231篇 |
1990年 | 237篇 |
1989年 | 163篇 |
1988年 | 122篇 |
1987年 | 84篇 |
1986年 | 102篇 |
1985年 | 66篇 |
1984年 | 41篇 |
1983年 | 39篇 |
1982年 | 37篇 |
1981年 | 21篇 |
1980年 | 8篇 |
1979年 | 5篇 |
1976年 | 1篇 |
1957年 | 4篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
Potential Analysis - We establish some exact asymptotic results for a matching problem with respect to a family of beta distributions. Let X1,…,Xn be independent random variables with common... 相似文献
2.
Gürbüzbalaban Mert Ruszczyński Andrzej Zhu Landi 《Journal of Optimization Theory and Applications》2022,194(3):1014-1041
Journal of Optimization Theory and Applications - We consider a distributionally robust formulation of stochastic optimization problems arising in statistical learning, where robustness is with... 相似文献
3.
Hua Saixiang Zhu Huichao Wang Xiao Wu Mingyuan Wu Qingyun Liu Jiuyi Yang Jianjun Zhang Jianan 《Cellulose (London, England)》2022,29(13):7465-7475
Cellulose - Ultraviolet (UV) protective cotton fabric is a convenient and reliable way to protect human body from sunlight. Herein, a polymerizable UV-absorber,... 相似文献
4.
This study is to numerically test the interfacial instability of ferrofluid flow under the presence of a vacuum magnetic field. The ferrofluid parabolized stability equations(PSEs) are derived from the ferrofluid stability equations and the Rosensweig equations, and the characteristic values of the ferrofluid PSEs are given to describe the ellipticity of ferrofluid flow. Three numerical models representing specific cases considering with/without a vacuum magnetic field or viscosity are created to mathematically examine the interfacial instability by the computation of characteristic values. Numerical investigation shows strong dependence of the basic characteristic of ferrofluid Rayleigh-Taylor instability(RTI) on viscosity of ferrofluid and independence of the vacuum magnetic field.For the shock wave striking helium bubble, the magnetic field is not able to trigger the symmetry breaking of bubble but change the speed of the bubble movement. In the process of droplet formation from a submerged orifice, the collision between the droplet and the liquid surface causes symmetry breaking. Both the viscosity and the magnetic field exacerbate symmetry breaking. The computational results agree with the published experimental results. 相似文献
5.
Yi-Tong Xu Tian-Yang Zhang Zheng Li Xiang-Nan Liu Yuan-Cheng Zhu Wei-Wei Zhao Hong-Yuan Chen Jing-Juan Xu 《Electroanalysis》2022,34(6):947-955
Photoelectrochemical (PEC) cytosensors, a combination of the PEC process and the living-cell assay, have emerged as a powerful tool in the analytical and biological science. This mini review provides a brief introduction of this arena and summaries the key steps about the development of PEC cytosensors with representative examples, followed by future prospects based on our own opinions. 相似文献
6.
Bingjie Chen Dr. Lianhai Zu Dr. Yao Liu Dr. Ruijing Meng Yutong Feng Prof. Chengxin Peng Feng Zhu Tianzi Hao Jiajia Ru Prof. Yonggang Wang Prof. Jinhu Yang 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(8):3161-3166
Incorporating nanoscale Si into a carbon matrix with high dispersity is desirable for the preparation of lithium-ion batteries (LIBs) but remains challenging. A space-confined catalytic strategy is proposed for direct superassembly of Si nanodots within a carbon (Si NDs⊂C) framework by copyrolysis of triphenyltin hydride (TPT) and diphenylsilane (DPS), where Sn atomic clusters created from TPT pyrolysis serve as the catalyst for DPS pyrolysis and Si catalytic growth. The use of Sn atomic cluster catalysts alters the reaction pathway to avoid SiC generation and enable formation of Si NDs with reduced dimensions. A typical Si NDs⊂C framework demonstrates a remarkable comprehensive performance comparable to other Si-based high-performance half LIBs, and higher energy densities compared to commercial full LIBs, as a consequence of the high dispersity of Si NDs with low lithiation stress. Supported by mechanic simulations, this study paves the way for construction of Si/C composites suitable for applications in future energy technologies. 相似文献
7.
Journal of Thermal Analysis and Calorimetry - In the present work, pyrolysis kinetic mechanism was studied for regenerated cellulosic fiber (RCF) and composite RCF containing silicon/nitrogen flame... 相似文献
8.
Nonlinear Dynamics - Under investigation is a generalized (3 + 1)-dimensional variable- coefficient Kadomtsev– Petviashvili equation in fluid mechanics. Various exact analytical solutions are... 相似文献
9.
10.
针对星模拟器与星敏感器观星的色温不匹配对星敏感器光信号定标精度产生的影响,设计了一种基于LED的多色温多星等单星模拟器,采用该系统模拟特定色温的星光用于星敏感器光信号定标,大幅降低了色温非匹配带来的定标误差。从理论上分析了色温非匹配影响星敏感器光信号的定标精度的机理;根据设计指标确定了星模拟器的设计方案,主要解决了光源的选型、多色温多星等单星模拟器驱动和控制系统、色温星等匹配算法、多色温多星等单星模拟器软件设计四项关键技术问题;对多色温多星等单星模拟器进行了标定和性能测试:0等星4000K和3等星7000 K星光的光谱匹配误差分别为4.87%和7.83%,星等等级分别为0.03和2.93;光源稳定后,多色温多星等单星模拟器的平行光管出口Φ100 mm口径内的照度非均匀度为6.5%,均满足设计指标。 相似文献