全文获取类型
收费全文 | 204750篇 |
免费 | 2329篇 |
国内免费 | 519篇 |
专业分类
化学 | 112722篇 |
晶体学 | 3674篇 |
力学 | 8032篇 |
综合类 | 11篇 |
数学 | 19490篇 |
物理学 | 63669篇 |
出版年
2020年 | 1786篇 |
2019年 | 1980篇 |
2018年 | 2280篇 |
2017年 | 2387篇 |
2016年 | 3587篇 |
2015年 | 2253篇 |
2014年 | 3625篇 |
2013年 | 9189篇 |
2012年 | 6745篇 |
2011年 | 8299篇 |
2010年 | 5812篇 |
2009年 | 5748篇 |
2008年 | 7357篇 |
2007年 | 7300篇 |
2006年 | 6900篇 |
2005年 | 6273篇 |
2004年 | 5711篇 |
2003年 | 5248篇 |
2002年 | 5016篇 |
2001年 | 6176篇 |
2000年 | 4656篇 |
1999年 | 3531篇 |
1998年 | 2761篇 |
1997年 | 2717篇 |
1996年 | 2615篇 |
1995年 | 2448篇 |
1994年 | 2338篇 |
1993年 | 2175篇 |
1992年 | 2828篇 |
1991年 | 2733篇 |
1990年 | 2674篇 |
1989年 | 2691篇 |
1988年 | 2713篇 |
1987年 | 2722篇 |
1986年 | 2592篇 |
1985年 | 3303篇 |
1984年 | 3314篇 |
1983年 | 2599篇 |
1982年 | 2710篇 |
1981年 | 2763篇 |
1980年 | 2533篇 |
1979年 | 2875篇 |
1978年 | 2861篇 |
1977年 | 2981篇 |
1976年 | 2816篇 |
1975年 | 2553篇 |
1974年 | 2510篇 |
1973年 | 2466篇 |
1972年 | 1702篇 |
1968年 | 1703篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
41.
Romanenko G. V. Letyagin G. A. Maryunina K. Yu. Bogomyakov A. S. Nishihara S. Inoue K. Ovcharenko V. I. 《Russian Chemical Bulletin》2020,69(8):1530-1536
Russian Chemical Bulletin - The study is concerned with structural rearrangements in the crystals of heterospin complexes Cu(hfac)2 with nitroxide radicals LR (hfac is hexafluoroacetylacetonate, LR... 相似文献
42.
Amphiphilic block copolymer self‐assemblies of poly(NVP)‐b‐poly(MDO‐co‐vinyl esters): Tunable dimensions and functionalities 下载免费PDF全文
Guillaume G. Hedir A. Pitto‐Barry Andrew P. Dove Rachel K. O'Reilly 《Journal of polymer science. Part A, Polymer chemistry》2015,53(23):2699-2710
Functional, degradable polymers were synthesized via the copolymerization of vinyl acetate (VAc) and 2‐methylene‐1,3‐dioxepane (MDO) using a macro‐xanthate CTA, poly(N‐vinylpyrrolidone), resulting in the formation of amphiphilic block copolymers of poly(NVP)‐b‐poly(MDO‐co‐VAc). The behavior of the block copolymers in water was investigated and resulted in the formation of self‐assembled nanoparticles containing a hydrophobic core and a hydrophilic corona. The size of the resultant nanoparticles was able to be tuned with variation of the hydrophilic and hydrophobic segments of the core and corona by changing the incorporation of the macro‐CTA as well as the monomer composition in the copolymers, as observed by Dynamic Light Scattering, Static Light Scattering, and Transmission Electron Microscopy analyses. The concept was further applied to a VAc derivative monomer, vinyl bromobutanoate, to incorporate further functionalities such as fluorescent dithiomaleimide groups throughout the polymer backbone using azidation and “click” chemistry as postpolymerization tools to create fluorescently labeled nanoparticles. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 2699–2710 相似文献
43.
Journal of Experimental and Theoretical Physics - A systematic nonperturbative scheme for calculating the ground state energy is adapted for studying systems of strongly correlated electrons on a... 相似文献
44.
45.
46.
47.
48.
Pan Huang Dawen Xu Robert M. Reich Felix Kaiser Boping Liu Fritz E. Kühn 《Tetrahedron letters》2019,60(24):1574-1577
A first example of an Et2Zn mediated silylation of 1-aklynes is reported. A series of functional groups are tolerated in this reaction. Mechanistic studies support Zn alkynilides as intermediates in the reaction. This reaction protocol provides a practical method for the preparation of alkynylsilanes and expands the application of organometallic zinc in organic synthesis. 相似文献
49.
A combination of 1,3-dihalo-5,5-dimethylhydantoin (X = Br, Cl) and sodium nitrite in the presence of wet SiO2 was used as an effective nitrosating agent for the nitrosation of N,N-dialkyl amines to their corresponding nitroso derivatives under mild and heterogeneous conditions in good to excellent yields. 相似文献
50.
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