全文获取类型
收费全文 | 33900篇 |
免费 | 5619篇 |
国内免费 | 4264篇 |
专业分类
化学 | 24372篇 |
晶体学 | 403篇 |
力学 | 2092篇 |
综合类 | 258篇 |
数学 | 4161篇 |
物理学 | 12497篇 |
出版年
2024年 | 17篇 |
2023年 | 706篇 |
2022年 | 804篇 |
2021年 | 1069篇 |
2020年 | 1451篇 |
2019年 | 1401篇 |
2018年 | 1140篇 |
2017年 | 1088篇 |
2016年 | 1684篇 |
2015年 | 1622篇 |
2014年 | 1858篇 |
2013年 | 2522篇 |
2012年 | 3071篇 |
2011年 | 3234篇 |
2010年 | 2195篇 |
2009年 | 2085篇 |
2008年 | 2302篇 |
2007年 | 2055篇 |
2006年 | 1878篇 |
2005年 | 1639篇 |
2004年 | 1241篇 |
2003年 | 965篇 |
2002年 | 935篇 |
2001年 | 717篇 |
2000年 | 674篇 |
1999年 | 721篇 |
1998年 | 579篇 |
1997年 | 545篇 |
1996年 | 573篇 |
1995年 | 459篇 |
1994年 | 428篇 |
1993年 | 323篇 |
1992年 | 301篇 |
1991年 | 287篇 |
1990年 | 256篇 |
1989年 | 183篇 |
1988年 | 131篇 |
1987年 | 137篇 |
1986年 | 118篇 |
1985年 | 118篇 |
1984年 | 61篇 |
1983年 | 59篇 |
1982年 | 43篇 |
1981年 | 25篇 |
1980年 | 15篇 |
1979年 | 11篇 |
1976年 | 9篇 |
1975年 | 11篇 |
1957年 | 7篇 |
1936年 | 6篇 |
排序方式: 共有10000条查询结果,搜索用时 218 毫秒
31.
Crystallography Reports - A novel 3D metal coordination polymer, {[Na4(µ2-H2O)(DMF)2(BCT)2]?DMF}n (I) (DMF = N,N-dimethylformamide, H2BCT =... 相似文献
32.
Hu Yinlong Hua Tianyang Chen Michael Z. Q. Shi Shang Sun Yonghui 《Nonlinear dynamics》2021,105(1):99-112
Nonlinear Dynamics - In this paper, the instability of semi-active control systems caused by the utilization of semi-active inerters is analyzed. The purpose of this study is to demonstrate the... 相似文献
33.
Sun Yuan Luo Shunlong Lei Xiangyun 《International Journal of Theoretical Physics》2021,60(9):3211-3224
International Journal of Theoretical Physics - Gram matrices arise naturally in the consideration of pair-wise overlap of a family of vectors or quantum pure states, and play an important role in... 相似文献
34.
Wang Zhenya Chen Hui Yao Ligang Chen Xu Qi Xiaoli Zhang Jun 《Nonlinear dynamics》2021,106(3):2107-2130
Nonlinear Dynamics - Fault diagnosis of critical rotating machinery components is necessary to ensure safe operation. However, the commonly used rotating machinery fault diagnosis methods are... 相似文献
35.
Nonlinear Dynamics - Linearizing the equations of motion of a constrained multibody system is a common need in, for example, stability analyses. While the theory of modelling multibody systems is... 相似文献
36.
Bohuai Xiao Jianqiao Dong Zhiye Wang Xu Wang Mingjun Sun Jing Guo Gongming Qian Yunchuan Li Shuai Chang 《Chemphyschem》2022,23(7):e202100833
One important prerequisite for the fabrication of molecular functional device strongly relies on the understanding the conducting behaviors of the metal-molecule-metal junction that can respond to an external stimulus. The model Lewis basic molecule 4,4′-(pyridine-3,5-diyl)dibenzonitrile (DBP), which can react with Lewis acid and protic acid, was synthesized. Then, the molecular conducting behavior of DBP, DBP-B(C6F5)3, and DBP-TfOH (DBP-B(C6F5)3, and DBP-TfOH were produced by Lewis acid and protonic acid treatment of DBP) was researched and compared. Given that their identical physical paths for DBP, DBP-B(C6F5)3, and DBP-TfOH to sustain charge transport, our results indicate that modifying the molecular electronic structure, even not directly changing the conductive physical backbone, can tune the charge transporting ability by nearly one order of magnitude. Furthermore, the addition of another Lewis base triethylamine (of stronger alkaline than DBP), to Lewis acid-base pair reverts the electrical properties back to that of a single DBP junction, that is constructive to propose a useful but simple strategy for the design and construction of reversible and controllable molecular device based on pyridine derived molecule. 相似文献
37.
Xu Yifan Zhang Hehe Ding Tangjing Tian Ruiqi Sun Dongmei Wang Ming-Sheng Zhou Xiaosi 《中国科学:化学(英文版)》2022,65(9):1807-1816
Science China Chemistry - Due to their enormous potential for large-scale energy storage, rechargeable potassium-ion batteries have been widely researched and developed. However, the drastic volume... 相似文献
38.
Mathematical Notes - Let $$\mathbb N$$ denote the set of all nonnegative integers, and let $$A\subseteq\mathbb N$$ . Let $$h,n\in\mathbb N$$ , $$h\ge 2$$ and $$r_h(A,n)=\#\{(a_1,\dots,a_h)\in... 相似文献
39.
Ryu Hoon-Hee Lee Soo-Been Sun Yang-Kook 《Journal of Solid State Electrochemistry》2022,26(9):2097-2105
Journal of Solid State Electrochemistry - Preparing a high-performance Ni-rich single-crystal cathode for Li-ion batteries is challenging. This is because calcination must be performed at a high... 相似文献
40.
Si-Yang Feng Tao Zheng Ai-Jing Sun Zuo-Xiang Wang 《Molecular Crystals and Liquid Crystals》2019,692(1):43-52
AbstractComplexes of [CdL2(NO3)2]·1.5H2O and [Ag2(μ-L)2(NO3)2] were synthesized by the reactions of 2-p-methylphenyl-5-(2-pyridyl)-1,3,4-thiadiazole (L) with Cd(NO3)2·4H2O and AgNO3, respectively. Their structures were determined by single crystal X-ray diffraction. The photophysical property and thermal stability were characterized by FT???IR, UV???Vis absorption, fluorescence, and thermogravimetric analysis (TGA). Both complexes belong to the triclinic system with space group p???1. The central metal of [CdL2(NO3)2]·1.5H2O has a distorted octahedral geometry [CdN4O2], while two central Ag(I) atoms of [Ag2(μ-L)2(NO3)2] exhibit distorted tetrahedral geometries [AgN3O]. 相似文献