全文获取类型
收费全文 | 693804篇 |
免费 | 30748篇 |
国内免费 | 12564篇 |
专业分类
化学 | 403537篇 |
晶体学 | 9584篇 |
力学 | 31368篇 |
综合类 | 584篇 |
数学 | 81838篇 |
物理学 | 210205篇 |
出版年
2022年 | 5756篇 |
2021年 | 7909篇 |
2020年 | 9884篇 |
2019年 | 10971篇 |
2018年 | 11124篇 |
2017年 | 10532篇 |
2016年 | 17854篇 |
2015年 | 13690篇 |
2014年 | 18305篇 |
2013年 | 35669篇 |
2012年 | 30521篇 |
2011年 | 34909篇 |
2010年 | 25251篇 |
2009年 | 24871篇 |
2008年 | 30818篇 |
2007年 | 29531篇 |
2006年 | 27346篇 |
2005年 | 24361篇 |
2004年 | 21792篇 |
2003年 | 18987篇 |
2002年 | 19212篇 |
2001年 | 20217篇 |
2000年 | 15825篇 |
1999年 | 12236篇 |
1998年 | 10148篇 |
1997年 | 9874篇 |
1996年 | 9661篇 |
1995年 | 8542篇 |
1994年 | 8344篇 |
1993年 | 7977篇 |
1992年 | 8575篇 |
1991年 | 8599篇 |
1990年 | 8112篇 |
1989年 | 7735篇 |
1988年 | 7533篇 |
1987年 | 7344篇 |
1986年 | 7075篇 |
1985年 | 9133篇 |
1984年 | 9172篇 |
1983年 | 7438篇 |
1982年 | 7656篇 |
1981年 | 7412篇 |
1980年 | 6850篇 |
1979年 | 7347篇 |
1978年 | 7668篇 |
1977年 | 7593篇 |
1976年 | 7526篇 |
1975年 | 6984篇 |
1974年 | 7064篇 |
1973年 | 7039篇 |
排序方式: 共有10000条查询结果,搜索用时 296 毫秒
41.
Physics of Atomic Nuclei - In this paper, the analysis of the relation between the multiplication factor of neutrons of the multiplying system measured in critical experiments and the system... 相似文献
42.
Set-Valued and Variational Analysis - In a Hilbert framework ℌ, we study the convergence properties of a Newton-like inertial dynamical system governed by a general maximally monotone... 相似文献
43.
M. Amar D. Andreucci R. Gianni C. Timofte 《Journal of Mathematical Analysis and Applications》2021,493(2):124533
We prove a well-posedness result for two pseudo-parabolic problems, which can be seen as two models for the same electrical conduction phenomenon in heterogeneous media, neglecting the magnetic field. One of the problems is the concentration limit of the other one, when the thickness of the dielectric inclusions goes to zero. The concentrated problem involves a transmission condition through interfaces, which is mediated by a suitable Laplace-Beltrami type equation. 相似文献
44.
Kobayashi M. Zhang Y. Ishikawa H. Sun J. Oddershede J. Juul Jensen D. Miura H. 《Experimental Mechanics》2021,61(5):817-828
Experimental Mechanics - The internal strain distribution developing during plastic deformation is important for understanding the mechanical properties of polycrystalline materials. Such... 相似文献
45.
Jiraya Kiriratnikom Xun Zhang Xiaohan Cao Bo Chu Chengjian Zhang Xinghong Zhang 《Journal of polymer science. Part A, Polymer chemistry》2022,60(15):2262-2268
Facile construction of sulfur-rich polymers using readily available raw chemicals is an area aggressively pursued but challenging. Herein we use common feedstocks of ethylene oxide (EO), propylene oxide (PO), and carbonyl sulfide (COS) to synthesize copoly(thioether)s which are traditionally produced from unpleasant and difficult to store episulfides. In this protocol, the EO/COS coupling selectively generates a pure poly(ethylene sulfide) (PES) with melting temperature (Tm) values up to 172°C and high yields up to 98%. The EO/PO/COS terpolymerization leads to the incorporation of soft poly(propylene sulfide) (PPS) and hard PES segments together, affording a random PES-co-PPS copoly(thioether) with the complete consumption of EO and PO. Additionally, by simply varying the EO/PO feeding ratio, the obtained copoly(thioether)s possess tunable thermal properties, Tm values in the range of 76–144°C, and excellent solubility. These copolymerizations are conducted in one-pot/one-step at industrially favored reaction temperatures of 100–120°C using catalysts of common organic bases, suggesting a facile and practical manner. Especially, the copoly(thioether) exhibits high refractive indices up to 1.68 owing to its high sulfur content, suggesting a broad application prospect in optical materials. 相似文献
46.
Kopytov G. F. Malyshko V. V. Goryachko A. I. Sharafan M. V. Churkina A. V. Moiseev A. V. Shashkov D. I. Lyasota O. M. 《Russian Physics Journal》2021,64(2):255-260
Russian Physics Journal - The specific features of the sorption activity of silver nanoparticles (AgNPs) on biodegradable polymers of natural (collagen) and artificial (polyamide 6.6) origin have... 相似文献
47.
Kuz’mina L. G. Navasardyan M. A. Kalle P. Bezzubov S. I. 《Crystallography Reports》2021,66(3):420-423
Crystallography Reports - The crystal and molecular structures of Cl–C6H4–O–C16H33 (I) have been studied, and its differential scanning calorimetry (DSC) study is performed.... 相似文献
48.
Chromatographia - The present work deals with the optimization, validation and application of a versatile HPLC–DAD method for concurrent estimation of nine antimicrobials and proton pump... 相似文献
49.
50.