全文获取类型
收费全文 | 138288篇 |
免费 | 5187篇 |
国内免费 | 2898篇 |
专业分类
化学 | 65872篇 |
晶体学 | 1296篇 |
力学 | 8658篇 |
综合类 | 189篇 |
数学 | 40076篇 |
物理学 | 30282篇 |
出版年
2023年 | 717篇 |
2022年 | 678篇 |
2021年 | 1366篇 |
2020年 | 1545篇 |
2019年 | 1475篇 |
2018年 | 11815篇 |
2017年 | 11508篇 |
2016年 | 8272篇 |
2015年 | 2964篇 |
2014年 | 2637篇 |
2013年 | 4452篇 |
2012年 | 8176篇 |
2011年 | 14960篇 |
2010年 | 8428篇 |
2009年 | 8577篇 |
2008年 | 10294篇 |
2007年 | 12280篇 |
2006年 | 3648篇 |
2005年 | 4260篇 |
2004年 | 3888篇 |
2003年 | 3908篇 |
2002年 | 2734篇 |
2001年 | 1572篇 |
2000年 | 1549篇 |
1999年 | 1209篇 |
1998年 | 1034篇 |
1997年 | 910篇 |
1996年 | 1097篇 |
1995年 | 804篇 |
1994年 | 776篇 |
1993年 | 724篇 |
1992年 | 640篇 |
1991年 | 536篇 |
1990年 | 451篇 |
1989年 | 391篇 |
1988年 | 368篇 |
1987年 | 348篇 |
1986年 | 343篇 |
1985年 | 391篇 |
1984年 | 346篇 |
1983年 | 281篇 |
1982年 | 268篇 |
1981年 | 251篇 |
1980年 | 220篇 |
1979年 | 203篇 |
1978年 | 196篇 |
1977年 | 156篇 |
1976年 | 155篇 |
1975年 | 143篇 |
1973年 | 149篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
Zenon Moszner 《Aequationes Mathematicae》2018,92(4):617-625
We give the form of the output function in Ginsburg’s machine in which the input and output dictionaries are abelian groups and the transition function is of a special form. 相似文献
72.
73.
Mejía Hugo Fernando Giraldo Jiménez-Piqué Emilio Valdés Matías Procaccini Raúl Pellice Sergio 《Journal of Solid State Electrochemistry》2020,24(10):2451-2460
Journal of Solid State Electrochemistry - A novel material was developed using sol-gel chemistry and an environmental-friendly grafting process of clay nanoparticles. In a previous work of our... 相似文献
74.
Synthesis,Electronic Properties and WOLED Devices of Planar Phosphorus‐Containing Polycyclic Aromatic Hydrocarbons 下载免费PDF全文
Dr. François Riobé Rózsa Szűcs Dr. Pierre‐Antoine Bouit Dr. Denis Tondelier Bernard Geffroy Fátima Aparicio Julia Buendía Prof. Luis Sánchez Prof. Régis Réau Prof. László Nyulászi Prof. Muriel Hissler 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(17):6547-6556
We describe the synthesis and the physical properties of polyaromatic hydrocarbons (PAHs) containing a phosphorus atom at the edge. In particular, the impact of the successive addition of aromatic rings on the electronic properties was investigated by experimental (UV/Vis absorption, fluorescence, cyclic voltammetry) and theoretical studies (DFT). The physical properties recorded in solution and in the solid state showed that the P‐containing PAHs exhibit properties expected for an emitter in white organic light‐emitting diodes (WOLEDs). 相似文献
75.
76.
77.
Understanding and control of the surface properties such as molecular orientations are of great importance in numerous applications of ionic liquids. However, there remain discrepancies among the previous experimental and theoretical studies on the surface orientation and structures of room temperature ionic liquids(RTIL) systems. In this article, the orientation of 1-butyl-3-methylimidazolium([bmin]) cation at the air/liquid interface of a characteristic RTIL, 1-butyl-3-methylimidazolium hexafluorophosphate([bmim][PF6]), was investigated by the sum frequency generation vibrational spectroscopy(SFG-VS). Detailed polarization and experimental configuration analyses of the SFG-VS spectra showed the possibility of a small spectral splitting in the CH3 symmetric stretching region, which can be further attributed to the probable existence of multiple orientations for the interfacial [bmim] cations. In addition, the(N)–CH3 vibrations were absent, ruling out the prediction by several recent molecular dynamics simulations which state that portions of the [bmim] cations orient with a standing-up(N)–CH3 group at the ionic liquid surface. Hence, new realistic theoretical models have to be developed to reflect the complex nature of the ionic liquid surface. 相似文献
78.
79.
80.
A rapid method had been used for comparative study on Artemisia halodendron Turcz. and its two related plants by gas phase-mass spectrometry (GC-MS). The comparison of the volatile oils obtained in three plants by GC-MS were similar in 20 compositions. However, n-Hexadecanoic acid (10.40%), Biphenyl (7.867%) and 9,12-Octadecadienoic acid (7.25%) were the predominant in the volatile oils of A. halodendron Turcz., whereas these constituents did not exist in the other two plants. And the study investigated the effect of three plants against CCl4-induced hepatotoxicity in mice. 70% ethanol extracts of A. halodendron Turcz. showed weaker protective effect than the other two plants. It suggested that they provide a basis for the identification of the A. halodendron Turcz. from the other two plants and the ethanol extract from three plants exerted a protecting effect against hepatotoxicity. 相似文献