全文获取类型
收费全文 | 255163篇 |
免费 | 4198篇 |
国内免费 | 1381篇 |
专业分类
化学 | 141217篇 |
晶体学 | 3406篇 |
力学 | 9810篇 |
综合类 | 64篇 |
数学 | 30460篇 |
物理学 | 75785篇 |
出版年
2020年 | 2185篇 |
2019年 | 2232篇 |
2018年 | 2939篇 |
2017年 | 2986篇 |
2016年 | 4577篇 |
2015年 | 3154篇 |
2014年 | 4359篇 |
2013年 | 10612篇 |
2012年 | 9249篇 |
2011年 | 11121篇 |
2010年 | 7758篇 |
2009年 | 7375篇 |
2008年 | 10379篇 |
2007年 | 10382篇 |
2006年 | 9812篇 |
2005年 | 8970篇 |
2004年 | 7966篇 |
2003年 | 6941篇 |
2002年 | 6781篇 |
2001年 | 7406篇 |
2000年 | 5651篇 |
1999年 | 4083篇 |
1998年 | 3396篇 |
1997年 | 3370篇 |
1996年 | 3464篇 |
1995年 | 3047篇 |
1994年 | 3173篇 |
1993年 | 3024篇 |
1992年 | 3319篇 |
1991年 | 3226篇 |
1990年 | 3038篇 |
1989年 | 2927篇 |
1988年 | 2841篇 |
1987年 | 2798篇 |
1986年 | 2785篇 |
1985年 | 3740篇 |
1984年 | 3781篇 |
1983年 | 3161篇 |
1982年 | 3425篇 |
1981年 | 3188篇 |
1980年 | 2966篇 |
1979年 | 3153篇 |
1978年 | 3336篇 |
1977年 | 3367篇 |
1976年 | 3375篇 |
1975年 | 3107篇 |
1974年 | 3202篇 |
1973年 | 3209篇 |
1972年 | 2458篇 |
1971年 | 1997篇 |
排序方式: 共有10000条查询结果,搜索用时 3 毫秒
1.
Kinetics and Catalysis - The catalytic properties of a nickel phosphide catalyst supported on silica gel in the reductive amination of carbonyl compounds were studied in a flow reactor using... 相似文献
2.
Patrick Imrie Jianyong Jin 《Journal of polymer science. Part A, Polymer chemistry》2022,60(2):149-174
4D printing is an exciting branch of additive manufacturing. It relies on established 3D printing techniques to fabricate objects in much the same way. However, structures which fall into the 4D printed category have the ability to change with time, hence the “extra dimension.” The common perception of 4D printed objects is that of macroscopic single-material structures limited to point-to-point shape change only, in response to either heat or water. However, in the area of polymer 4D printing, recent advancements challenge this understanding. A host of new polymeric materials have been designed which display a variety of wonderful effects brought about by unconventional stimuli, and advanced additive manufacturing techniques have been developed to accommodate them. As a result, the horizons of polymer 4D printing have been broadened beyond what was initially thought possible. In this review, we showcase the many studies which evolve the very definition of polymer 4D printing, and reveal emerging areas of research integral to its advancement. 相似文献
3.
Yang T. L. Kao C. L. Kuo C. E. Yeh H. C. Li W. J. Li H. T. Chen C. Y. 《Chemistry of Natural Compounds》2022,58(5):825-827
Chemistry of Natural Compounds - A novel bibenzyl derivative, hydrangchinenin (1), was isolated from the stems of Hydrangea chinensis Maxim. (Hydrangeaceae). Its structure was determined on the... 相似文献
4.
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
5.
Filatova S. M. Guseva M. K. Bodrova T. G. Parshina D. V. Budanova U. A. Sebyakin Yu. L. 《Russian Journal of General Chemistry》2022,91(1):S13-S23
Russian Journal of General Chemistry - The review article traces the main trends of the synthetic approach to the solution of the problem of overcoming the resistance of pathogenic bacterial... 相似文献
6.
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
7.
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
8.
9.
10.
Li Y. Shi W. H. Dong L. M. Xu S. X. Huang H. J. Yin J. R. 《Journal of Applied Spectroscopy》2022,89(3):534-541
Journal of Applied Spectroscopy - Sr3B2O6:Dy3+, Eu3+ single-matrix white-light-emitting materials are prepared using the high-temperature solid-state method. The microstructure, emission spectrum,... 相似文献