全文获取类型
收费全文 | 907篇 |
免费 | 35篇 |
国内免费 | 5篇 |
专业分类
化学 | 592篇 |
晶体学 | 11篇 |
力学 | 29篇 |
数学 | 109篇 |
物理学 | 206篇 |
出版年
2024年 | 1篇 |
2023年 | 12篇 |
2022年 | 38篇 |
2021年 | 50篇 |
2020年 | 22篇 |
2019年 | 31篇 |
2018年 | 52篇 |
2017年 | 33篇 |
2016年 | 41篇 |
2015年 | 37篇 |
2014年 | 33篇 |
2013年 | 64篇 |
2012年 | 71篇 |
2011年 | 71篇 |
2010年 | 45篇 |
2009年 | 30篇 |
2008年 | 59篇 |
2007年 | 59篇 |
2006年 | 39篇 |
2005年 | 39篇 |
2004年 | 37篇 |
2003年 | 29篇 |
2002年 | 15篇 |
2001年 | 4篇 |
2000年 | 2篇 |
1999年 | 3篇 |
1998年 | 3篇 |
1997年 | 1篇 |
1996年 | 1篇 |
1995年 | 4篇 |
1994年 | 3篇 |
1992年 | 3篇 |
1991年 | 2篇 |
1990年 | 3篇 |
1989年 | 1篇 |
1987年 | 1篇 |
1984年 | 1篇 |
1981年 | 1篇 |
1980年 | 1篇 |
1978年 | 1篇 |
1977年 | 4篇 |
排序方式: 共有947条查询结果,搜索用时 15 毫秒
81.
The origin of the anomalously large value of the heat capacity of liquid water is discussed. Comparing the temperature dependence of the heat capacities for water with those for argon and hydrogen sulfide, we separate contributions of the translational and rotational degrees of freedom. The residual part is considered as being caused by the specific contributions of the transversal vibrations of H-bonds. The estimate for the number of H-bonds per molecule is obtained from the analysis of this contribution. This estimate is in quite good agreement with the estimates which follow from the analysis of the specific volume, heat of evaporation, and kinematic shear viscosity. 相似文献
82.
83.
Andrey B. Koldobskii Nikolay P. Tsvetkov Ekaterina V. Solodova Valery N. Kalinin 《Journal of fluorine chemistry》2010,131(8):852-9595
This paper describes a novel synthetic approach to 2-cyano-3-trifluoromethylthiophenes fused with cyclobutene rings with variable spiro conjunctions. The reaction of substituted 1-bromo-2-trifluoroacetylcyclobutenes with mercaptoacetonitrile results in the substitution of bromine with S-center to afford the corresponding nitriles in high yields, which form the target thiophenes by subsequent treatment of lithium 2,2,6,6-tetramethylpiperidide and acetic anhydride. 相似文献
84.
Nikolay L. Aleksandrov 《Proceedings of the Combustion Institute》2009,32(1):205-212
The kinetics of ignition in stoichiometric CnH2n+2:O2:Ar mixtures with 90% dilution for n = 1-5 has been studied experimentally and numerically under the action of a high-voltage nanosecond discharge. It was shown that the initiation of the discharge by a high-voltage pulse 115 kV in amplitude with a specific deposited energy of 10-30 mJ/cm3 leads to more than an order of magnitude decrease in the ignition delay time. The generation of atoms, radicals and excited and charged particles by the discharge was numerically described. The role of different atoms and radicals (O, H and CnH2n+1) was analyzed. The temporal evolution of the densities of intermediate components in the plasma assisted ignition was discussed. 相似文献
85.
A method for constructing binary self-dual codes having an automorphism of order p
2 for an odd prime p is presented in (S. Bouyuklieva et al. IEEE. Trans. Inform. Theory, 51, 3678–3686, 2005). Using this method, we investigate
the optimal self-dual codes of lengths 60 ≤ n ≤ 66 having an automorphism of order 9 with six 9-cycles, t cycles of length 3 and f fixed points. We classify all self-dual [60,30,12] and [62,31,12] codes possessing such an automorphism, and we construct
many doubly-even [64,32,12] and singly-even [66,33,12] codes. Some of the constructed codes of lengths 62 and 66 are with
weight enumerators for which the existence of codes was not known until now.
相似文献
86.
Dendronized Hyperbranched Macromolecules: Soft Matter with a Novel Type of Segmental Distribution
下载免费PDF全文
![点击此处可从《Angewandte Chemie (International ed. in English)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Priv.‐Doz. Dr. Albena Lederer Prof. Dr. Walther Burchard Tobias Hartmann Johannes S. Haataja Dr. Nikolay Houbenov Andreas Janke Dr. Peter Friedel Dr. Ralf Schweins Dr. Peter Lindner 《Angewandte Chemie (International ed. in English)》2015,54(43):12578-12583
Dendronization of a hyperbranched polyester with different generation dendrons leads to pseudo‐dendritic structures. The hyperbranched core is modified by the divergent coupling of protected monomer units to the functional groups. Compared to dendrimers, the synthetic effort is significantly less, but the properties are very close to those of high‐generation dendrimers. The number of functional groups, molar mass, and rheology behavior even in the early generation (G1–G4) pseudo‐dendrimers strongly resembles the behavior of dendrimers in higher generations (G5–G8). Comparison of the segmental and internal structure with perfect dendrimers is performed using SANS, dynamic light scattering and viscosity analysis, microscopy and molecular dynamics simulation. The interpretation of the results reveals unique structural characteristics arising from lower segmental density of the core, which turns into a soft nano‐sphere with a smooth surface even in the first generation. 相似文献
87.
Prof. Dr. Konstantin V. Kudryavtsev Chia‐Chun Yu Polina M. Ivantcova Prof. Dr. Vladimir I. Polshakov Dr. Andrei V. Churakov Prof. Dr. Stefan Bräse Prof. Dr. Nikolay S. Zefirov Prof. Dr. Jih‐Hwa Guh 《化学:亚洲杂志》2015,10(2):383-389
Functionalized oligomeric organic compounds with well‐defined β‐proline scaffold have been synthesized by a cycloadditive oligomerization approach in racemic and enantiopure forms. The structure of the novel β‐peptides was investigated by NMR spectroscopic and X‐ray methods determining the conformational shapes of the β‐proline oligomers in solution and solid states. The main structural elements subject to conformational switches are β‐peptide bonds between 5‐arylpyrrolidine‐2‐carboxylic acid units existing in Z/E configurations. The whole library of short β‐peptides and intermediate acrylamides has been tested on antiproliferative activity towards the hormone‐refractory prostate cancer cell line PC‐3 revealing several oligomeric compounds with low micromolar and submicromolar activities. Bromine‐substituted dimeric and trimeric acrylamides induced caspase‐dependent apoptosis of PC‐3 cells through cell‐cycle arrest and mitochondrial damage. 相似文献
88.
89.
90.
Nikolay Kuznetsov 《Comptes Rendus Mecanique》2004,332(1):73-78
This Note deals with the linearized water-wave problem involving a surface-piercing cylinder in water of infinite depth. A solution to this problem is proved to be unique for all values of the radian frequency when the cylinder intersecting the free surface at arbitrary angles is subjected to certain geometric arrangements. To cite this article: N. Kuznetsov, C. R. Mecanique 332 (2004). 相似文献