全文获取类型
收费全文 | 316980篇 |
免费 | 2451篇 |
国内免费 | 907篇 |
专业分类
化学 | 138546篇 |
晶体学 | 4325篇 |
力学 | 18318篇 |
综合类 | 3篇 |
数学 | 66478篇 |
物理学 | 92668篇 |
出版年
2021年 | 1339篇 |
2020年 | 1555篇 |
2019年 | 1617篇 |
2018年 | 18542篇 |
2017年 | 19106篇 |
2016年 | 11708篇 |
2015年 | 3507篇 |
2014年 | 3272篇 |
2013年 | 7289篇 |
2012年 | 12755篇 |
2011年 | 26972篇 |
2010年 | 16008篇 |
2009年 | 16363篇 |
2008年 | 21754篇 |
2007年 | 26588篇 |
2006年 | 6638篇 |
2005年 | 13435篇 |
2004年 | 9761篇 |
2003年 | 9530篇 |
2002年 | 6747篇 |
2001年 | 6107篇 |
2000年 | 4684篇 |
1999年 | 3397篇 |
1998年 | 2452篇 |
1997年 | 2487篇 |
1996年 | 2541篇 |
1995年 | 2221篇 |
1994年 | 2177篇 |
1993年 | 1995篇 |
1992年 | 2414篇 |
1991年 | 2516篇 |
1990年 | 2324篇 |
1989年 | 2294篇 |
1988年 | 2313篇 |
1987年 | 2295篇 |
1986年 | 2108篇 |
1985年 | 2607篇 |
1984年 | 2636篇 |
1983年 | 2102篇 |
1982年 | 2153篇 |
1981年 | 1999篇 |
1980年 | 1970篇 |
1979年 | 2254篇 |
1978年 | 2367篇 |
1977年 | 2200篇 |
1976年 | 2131篇 |
1975年 | 2000篇 |
1974年 | 1969篇 |
1973年 | 2050篇 |
1972年 | 1312篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
1.
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
2.
Chromatographia - We developed a simple, rapid, ecological RP-HPLC method for the estimation of Pitavastatin (PIT), Fenofibrate (FEN), and their impurities in a novel fixed dose combination. We... 相似文献
3.
Hassan E. A. M. Elabid A. E. A. Bashier E. O. Elagib T. H. H. 《Mechanics of Composite Materials》2022,58(2):261-270
Mechanics of Composite Materials - Carbon fiber (CF)/ polyamide (PA6) composites are one of the most promising thermoplastic materials for automobile applications. However, the interfacial... 相似文献
4.
Petrov P. A. Filippova E. A. Kompankov N. B. Sukhikh T. S. Sokolov M. N. 《Journal of Structural Chemistry》2022,63(3):470-475
Journal of Structural Chemistry - A new polymorph of the [ReCl3(MeCN)(PPh3)2] complex is synthesized and characterized by single crystal X-ray diffraction (XRD). Its recrystallization from the... 相似文献
5.
Dr. Yolimar Gil Dr. Alejandro Castro-Alvarez Dr. Pablo Fuentealba Prof. Evgenia Spodine Dr. Daniel Aravena 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(48):e202200336
Enhancement of axial magnetic anisotropy is the central objective to push forward the performance of Single-Molecule Magnet (SMM) complexes. In the case of mononuclear lanthanide complexes, the chemical environment around the paramagnetic ion must be tuned to place strongly interacting ligands along either the axial positions or the equatorial plane, depending on the oblate or prolate preference of the selected lanthanide. One classical strategy to achieve a precise chemical environment for a metal centre is using highly structured, chelating ligands. A natural approach for axial-equatorial control is the employment of macrocycles acting in a belt conformation, providing the equatorial coordination environment, and leaving room for axial ligands. In this review, we present a survey of SMMs based on the macrocycle belt motif. Literature systems are divided in three families (crown ether, Schiff-base and metallacrown) and their general properties in terms of structural stability and SMM performance are briefly discussed. 相似文献
6.
Journal of Structural Chemistry - Atomic and electronic structures of cyclic organosilicon compound 9,9,10,10-tetraethynyl-9,10-dihydrodisilaanthracene are studied by the density functional theory.... 相似文献
7.
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
8.
Varfolomeev S. D. Panin A. A. Semenova N. A. Ublinskiy M. V. Akhadov T. A. Bykov V. I. Tsybenova S. B. 《Russian Chemical Bulletin》2022,71(3):591-594
A kinetic study of the effect of thermoheliox (inhalation of a helium and oxygen mixture, 70 °C) on the functional hemodynamics of the human brain by functional magnetic resonance imaging was carried out. The dynamic responses of the BOLD signal were found to be biphasic. An empirical equation describing the first phase of the hemodynamic response to visual stimulus was proposed. It was shown that preliminary inhalation of thermoheliox stimulates the hemodynamic responses by slowing down the vasoconstriction.
相似文献9.
Numerical Algorithms - This paper considers different versions of block-column iterative (BCI) methods for solving nonnegative constrained linear least squares problems. We present the convergence... 相似文献
10.
Theoretical and Mathematical Physics - We consider three one-dimensional superconducting structures: 1) the one with $$p$$ -wave superconductivity; 2) the main experimental model of a nanowire with... 相似文献