全文获取类型
收费全文 | 7354篇 |
免费 | 1028篇 |
国内免费 | 1139篇 |
专业分类
化学 | 5876篇 |
晶体学 | 130篇 |
力学 | 368篇 |
综合类 | 135篇 |
数学 | 861篇 |
物理学 | 2151篇 |
出版年
2024年 | 7篇 |
2023年 | 102篇 |
2022年 | 197篇 |
2021年 | 194篇 |
2020年 | 273篇 |
2019年 | 260篇 |
2018年 | 210篇 |
2017年 | 197篇 |
2016年 | 350篇 |
2015年 | 335篇 |
2014年 | 425篇 |
2013年 | 537篇 |
2012年 | 602篇 |
2011年 | 668篇 |
2010年 | 553篇 |
2009年 | 484篇 |
2008年 | 550篇 |
2007年 | 551篇 |
2006年 | 515篇 |
2005年 | 371篇 |
2004年 | 367篇 |
2003年 | 272篇 |
2002年 | 295篇 |
2001年 | 226篇 |
2000年 | 158篇 |
1999年 | 135篇 |
1998年 | 104篇 |
1997年 | 90篇 |
1996年 | 80篇 |
1995年 | 51篇 |
1994年 | 46篇 |
1993年 | 50篇 |
1992年 | 41篇 |
1991年 | 32篇 |
1990年 | 36篇 |
1989年 | 20篇 |
1988年 | 15篇 |
1987年 | 15篇 |
1986年 | 14篇 |
1985年 | 14篇 |
1984年 | 7篇 |
1983年 | 13篇 |
1982年 | 7篇 |
1981年 | 5篇 |
1980年 | 8篇 |
1978年 | 6篇 |
1974年 | 3篇 |
1973年 | 3篇 |
1969年 | 3篇 |
1928年 | 3篇 |
排序方式: 共有9521条查询结果,搜索用时 15 毫秒
141.
142.
Xiao Ling WANG Wei JIAO Xun LIAO Shu Ling PENG Li Sheng DING 《中国化学快报》2006,17(7):916-918
The roots of Paeonia lactiflora Pall. is one of the most important traditional Chinese medicines, which has been used for the treatment of dizziness, spasm, menstrual disorder, spontaneous and night sweating, and as a general analgesic1. Chemical constitu… 相似文献
143.
Super/subcritical fluid chromatography chiral separations with macrocyclic glycopeptide stationary phases 总被引:2,自引:0,他引:2
Liu Y Berthod A Mitchell CR Xiao TL Zhang B Armstrong DW 《Journal of chromatography. A》2002,978(1-2):185-204
The chiral recognition capabilities of three macrocyclic glycopeptide chiral selectors, namely teicoplanin (Chirobiotic T), its aglycone (Chirobiotic TAG) and ristocetin (Chirobiotic R), were evaluated with supercritical and subcritical fluid mobile phases. A set of 111 chiral compounds including heterocycles, analgesics (nonsteroidal antiinflamatory compounds), beta-blockers, sulfoxides, N-protected amino acids and native amino acids was separated on the three chiral stationary phases (CSPs). All separations were done with an outlet pressure regulated at 100 bar, 31 degrees C and at 4 ml/min. Various amounts of methanol ranging from 7 to 67% (v/v) were added to the carbon dioxide along with small amounts (0.1 to 0.5%, v/v) of triethylamine and/or trifluoroacetic acid. The Chirobiotic TAG CSP was the most effective closely followed by the Chirobiotic T column. Both columns were able to separate, partially or fully, 92% of the enantiomers of the compound set. The ristocetin chiral selector could partially or baseline resolve only 60% of the enantiomers tested. All separations were done in less than 15 min and 70% were done in less than 4 min. The speed of the separations is the main advantage of the use of SFC compared to normal-phase HPLC. In addition, SFC is advantageous for preparative separations with easy solute recovery and solvent disposal. 相似文献
144.
Studies on Phase Behavior of Alkyl Polyglucoside Based on Microemulsions with Modified Fishlike Phase Diagram 总被引:1,自引:0,他引:1
JinLingCHAI GanZuoLI ZhaoYuDIAO GaoYongZHANG 《中国化学快报》2004,15(3):361-364
The three-phase behavior in the quaternary system of an alkyl (C8/10^- or C12/14^-)polyglucoside / 1-butanol / n-octane / water has been studied at 40℃ with the modified fishlike phase diagram, which is presented by us for the first time. The mass fraction of 1-butanol in the hydrophile-lipophile balanced interfacial layer, A^S, the coordinates of the start point B and the end point E of the phase diagram, and the solubilities of alkyl polyglucoside and 1-butanol in n-octane phase were calculated. The solubilization of the microemulsion was also discussed. 相似文献
145.
钒的氨基酸配合物具有重要的生物和医学意义。VO(Ⅱ)-组氨酸配合物及VO(Ⅱ)-π受体二元配合物的ESR研究已有报道。但是VO(Ⅱ)-氨基酸-π受体三元配合物的结构及其ESR研究至今未见报道。本文考察了VOSO_4与组氨酸(His)和邻菲啰啉(Phen)及α,α′-联吡啶(bipy)三元体系在不同酸度(pH=1~14)的乙二醇/水(1:1)溶液中低温(173K)ESR波谱,获得了不同pH条件下配合情况的详细信息。 相似文献
146.
147.
A logarithmic expression is proposed to describe relaxation of the polar order in side chain polymers,together with a new way of plotting temperature dependent relaxation data.This results in a straight line extending even below the glass transition temperature in the case of poled nonlinear optics (NLO) side chain polymers.A simple procedure to determine the rotational diffusion constant Dr is given and Dr values of several polymer systems have been evaluated and compared with each other.It appears that,starting from the conventional and well known poled polymer system currently applied,a further lowering of Dr by about 3 orders of magnitude is necessary in order to reach an acceptable orientational stability or lifetime of poled polymers for practical applications.Attempts have been made to introduce electron push-pull substituents into high thermostable molecular frameworks and results of preliminary measurements are reported. 相似文献
148.
Journal of Theoretical Probability - We investigate the space-time regularity of the local time associated with Volterra–Lévy processes, including Volterra processes driven by $$\alpha... 相似文献
149.
Theoretical and Mathematical Physics - The initial-boundary value problems for the matrix Lakshmanan–Porsezian–Daniel system are studied by utilizing the Fokas unified transform... 相似文献
150.