首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   580645篇
  免费   6833篇
  国内免费   2605篇
化学   317588篇
晶体学   8142篇
力学   24827篇
综合类   72篇
数学   69501篇
物理学   169953篇
  2020年   4232篇
  2019年   4435篇
  2018年   5154篇
  2017年   5173篇
  2016年   8629篇
  2015年   6253篇
  2014年   8890篇
  2013年   25228篇
  2012年   19522篇
  2011年   24073篇
  2010年   16054篇
  2009年   15978篇
  2008年   22378篇
  2007年   22754篇
  2006年   21766篇
  2005年   19727篇
  2004年   17684篇
  2003年   15740篇
  2002年   15574篇
  2001年   16959篇
  2000年   13083篇
  1999年   10238篇
  1998年   8488篇
  1997年   8333篇
  1996年   8289篇
  1995年   7499篇
  1994年   7295篇
  1993年   6986篇
  1992年   7739篇
  1991年   7698篇
  1990年   7251篇
  1989年   7024篇
  1988年   7190篇
  1987年   6858篇
  1986年   6680篇
  1985年   9167篇
  1984年   9404篇
  1983年   7795篇
  1982年   8404篇
  1981年   8179篇
  1980年   7785篇
  1979年   8187篇
  1978年   8417篇
  1977年   8390篇
  1976年   8427篇
  1975年   8019篇
  1974年   8032篇
  1973年   8191篇
  1972年   5502篇
  1971年   4365篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
3.
In this work, we have used the MuMax3 software to simulate devices consisting of a ferromagnetic thin film placed over a heavy metal thin film. The devices are two interconnected partial-disks where a Néel domain wall is formed in the disks junction. In our simulations we investigate devices with disk radius r=50 nm and different distance d between the disks centers (from d=12 nm to d=2R=100 nm). By applying strong sinusoidal external magnetic fields, we find a mechanism able to create, annihilate and even manipulate a skyrmion in each side of the device. This mechanism is discussed in terms of interactions between skyrmion and domain wall. The Néel domain wall formed in the center of the device interacts with the Néel skyrmion, leading to a process of transporting a skyrmion from one disk to the other periodically. Our results have relevance for potential applications in spintronics such as logical devices.  相似文献   
4.
5.
6.
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   
7.
    
The reaction of [{(η5-C5Me5)M(μ-Cl)Cl}2] {where M = Rh (1), Ir (2)} with functionalized phosphine viz., diphenyl-2-pyridylphosphine (PPh2Py) in dichloromethane solvent yield neutral ϰ1-P-coordinated rhodium and iridium complexes [(η5-C5Me5)RhCl21-P-PPh2Py)]3 and [(η5-C5Me5) IrCl21-P-PPh2Py)]4. Reaction of complexes 1 and 2 with the ligand PPh2Py in methanol under reflux give bis-substituted complexes such as [(η5-C5Me5)RhCl(ϰ1-P-PPh2Py)2]+ 5 and [(η5-C5Me5)IrCl(ϰ1-P-PPh2Py)2]+ 6, whereas stirring in methanol at room temperature gives P-, N-chelating complexes of the type [(η5-C5Me5)RhCl(ϰ2-P-N-PPh2Py)]+ 7 and [(η5-C5Me5)IrCl(ϰ2-P-N-PPh2Py)]+ 8. Neutral ϰ1-P-coordinated complexes [(η5-C5Me5)RhCl21-P-PPh2Py)]3 and [(η5-C5Me5)IrCl21-P-PPh2Py)]4 easily undergo conversion to the cationic P-, N-chelating complexes [(η5-C5Me5)RhCl(ϰ2-P-N-PPh2Py)]+ 7 and [(η5-C5Me5) IrCl(ϰ2-P, N-PPh2Py)]+ 8 on stirring in methanol at room temperature. These complexes are characterized by FT-IR and FT-NMR spectroscopy as well as analytical methods. The molecular structures of the representative complexes [(η5-C5Me5)RhCl21-P-PPh2Py)]3, [(η5-C5Me5)IrCl21-P-PPh2Py)]4 and hexafluorophosphate salt of complex [(η5-C5Me5)IrCl(ϰ2-P-PPh2Py)2]+ 6 are established by single-crystal X-ray diffraction methods  相似文献   
8.
The European Physical Journal E - The isothermal gas adsorption of two hexane isomers (n-hexane and cyclohexane) in the mesopores of MCM-41 silica have been investigated by small angle neutron...  相似文献   
9.
10.
The paper discusses the applicability of quasi-crystalline approximation to describing the thermal motion of water molecules in their normal and supercooled states. The problem is subjected to the critical analysis of experimental data on incoherent scattering of slow neutrons based on theories developed by Singwi-Sjolander [1] and Oskotsky [2] modified to duly take into account the limited applicability range of diffusion approximation. The applicability conditions of quasi-crystalline approximation are shown to be consistently satisfied only when water is in supercooled state and within a narrow temperature range above the melting temperature.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号