全文获取类型
收费全文 | 18826篇 |
免费 | 3877篇 |
国内免费 | 5145篇 |
专业分类
化学 | 12654篇 |
晶体学 | 734篇 |
力学 | 1527篇 |
综合类 | 918篇 |
数学 | 2724篇 |
物理学 | 9291篇 |
出版年
2025年 | 66篇 |
2024年 | 351篇 |
2023年 | 423篇 |
2022年 | 702篇 |
2021年 | 650篇 |
2020年 | 684篇 |
2019年 | 670篇 |
2018年 | 635篇 |
2017年 | 930篇 |
2016年 | 648篇 |
2015年 | 828篇 |
2014年 | 1052篇 |
2013年 | 1326篇 |
2012年 | 1268篇 |
2011年 | 1392篇 |
2010年 | 1413篇 |
2009年 | 1445篇 |
2008年 | 1703篇 |
2007年 | 1483篇 |
2006年 | 1546篇 |
2005年 | 1365篇 |
2004年 | 1027篇 |
2003年 | 745篇 |
2002年 | 738篇 |
2001年 | 827篇 |
2000年 | 821篇 |
1999年 | 501篇 |
1998年 | 290篇 |
1997年 | 219篇 |
1996年 | 239篇 |
1995年 | 180篇 |
1994年 | 191篇 |
1993年 | 159篇 |
1992年 | 190篇 |
1991年 | 122篇 |
1990年 | 131篇 |
1989年 | 108篇 |
1988年 | 104篇 |
1987年 | 124篇 |
1986年 | 83篇 |
1985年 | 64篇 |
1984年 | 79篇 |
1983年 | 67篇 |
1982年 | 50篇 |
1981年 | 44篇 |
1980年 | 32篇 |
1979年 | 35篇 |
1978年 | 17篇 |
1965年 | 13篇 |
1964年 | 15篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
1.
Prisoner's Dilemma Game with Heterogeneous Influential Effect on Regular Small-World Networks
下载免费PDF全文

The effect of heterogeneous influence of different individuals on the maintenance of co-operative behaviour is studied in an evolutionary Prisoner's Dilemma game with players located on the sites of regular small-world networks. The players interacting with their neighbours can either co-operate or defect and update their states by choosing one of the neighbours and adopting its strategy with a probability depending on the pay off difference. The selection of the neighbour obeys a preferential rule: the more influential a neighbour, the larger the probability it is picked. It is found that this simple preferential selection rule can promote continuously the co-operation of the whole population with the strengthening of the disorder of the underlying network. 相似文献
2.
A cDNA for human TNF-α (615bp) was isolated by means of polymerase chain reaction (PCR) using first strand cDNA from PMA-induced HL-60 cells as template. The result from sequencing the 615 bp cDNA fragment indicated that it corresponded to the entire sequence of mature human TNF coding region. Direct expression of mature human TNF was achieved using a plasmid pHT-1 constructed by ligation of the cDNA and a synthetic DNA. The IPTG-induced bacterial product (hTNF) showed cytotoxicity to mouse L-929 cells. The TNF activity was further identified by neutralization of a specific monoclonal antibody against human TNF-α. Approximately 80,000 units of activity were detected per ml of culture at A600=2. 相似文献
3.
LIU Si-Min WU Xiao-Jun YAO Jun-Hua WU Cheng-Tai 《有机化学》2003,23(Z1):261-262
Non-covalent attractive forces are commonly employed in biological systems to drive the assembly of highly orga nized supramolecular entities from relatively simple subunits. 相似文献
4.
5.
It is proved that the apparent transverse velocities β_(app) and the spectral powers at 10GHz P_(10) of the cores of known superluminal sources are correlated. An interpretation ofthis result within the framework of the relativistic jet model shows that the jet Lorentzfactor γ depends on the intrinsic luminosity of the sources. The probable existence of twosubpopulations of the superluminal sources is shown by a linear regression analysis. "Small"sources f i.e. the sources without extended emission or with a distance from the core tothe outer edge of the lobe<20 kpc, show lower β_(app) than the "large" objects; this can beinterpreted as an orientation effect. Since all BL Lac objects belong to the "small" class,this result sheds new light on such a question as why these sources have lower apparent ve-locities than the "classical" superluminal quasars. 相似文献
6.
Two copper(Ⅱ)coordination polymers{[Cu(bib)(nip)]·1.5H2O}n(1)and[Cu2(bib)(glu)2]n(2)(bib= 1,4-bis(2-methyl-imidazol-1-yl)butane,H2nip = 5-nitroisophthalic acid,... 相似文献
7.
PVC/MBS/纳米 BaSO4 复合材料的制备及其性能 总被引:1,自引:0,他引:1
采用熔融共混法制备聚氯乙烯(PVC)/甲基丙烯酸甲酯-丁二烯-苯乙烯共聚物(MBS)/纳米重晶石(nano-BaSO4)三元复合材料,考察其力学性能和热稳定性能,并用扫描电镜观察冲击断面的形态.结果表明:MBS 与 nano-BaSO4 可协同增韧 PVC;当 MBS、nano-BaSO4 的含量分别为 10%、1%时,材料的韧性和刚性可同时得以改善,其冲击断面表现出典型的韧性断裂特征;热重分析显示添加 1%nano-BaSO4 可显著提高 PVC/MBS 的热稳定性能,其第一降解阶段的初始分解温度和最快分解温度分别提高了 10℃和14℃. 相似文献
8.
SONG Gang ZHANG Kai CHEN YuanYuan LIU HuiLi WU Chao YU Li XIAO JingHua 《中国科学:物理学 力学 天文学(英文版)》2013,(4):680-684
We successfully investigate an optical bistability phenomenon in a layered structure consisting of Kretschmann configuration involving the Kerr-type nonlinear and the silver film. Pure theoretical approaches are employed to investigate that the surface plasmon could easily be coupled and both the reflection and transmission curves versus the incident intensity forms optical bistability. The transmission curves are greatly influenced by the thickness of the second silver film. These results may be useful for designing novel surface plasmon-based optical devices and will be essential for future classical and quantum information processes. 相似文献
9.
10.
本文提出光声相位精细谱法(PAPFS)。通过对层状物初始态光声相位扫描和对由此产生的PAPFS曲线的解析,可获取各层与光学热学和空间坐标相关的有价值的信息。本文用该法对彩色相纸作了逐层分析,并将结果与电镜作了比较。与PAPFS相关的层状物光声理论将在本文第Ⅱ部分中涉及。 相似文献