全文获取类型
收费全文 | 85541篇 |
免费 | 1839篇 |
国内免费 | 1330篇 |
专业分类
化学 | 29864篇 |
晶体学 | 857篇 |
力学 | 7167篇 |
综合类 | 46篇 |
数学 | 32892篇 |
物理学 | 17884篇 |
出版年
2023年 | 203篇 |
2022年 | 224篇 |
2021年 | 288篇 |
2020年 | 457篇 |
2019年 | 392篇 |
2018年 | 10696篇 |
2017年 | 10478篇 |
2016年 | 6414篇 |
2015年 | 1246篇 |
2014年 | 792篇 |
2013年 | 924篇 |
2012年 | 4501篇 |
2011年 | 11244篇 |
2010年 | 6127篇 |
2009年 | 6480篇 |
2008年 | 7021篇 |
2007年 | 9146篇 |
2006年 | 663篇 |
2005年 | 1631篇 |
2004年 | 1777篇 |
2003年 | 2178篇 |
2002年 | 1256篇 |
2001年 | 398篇 |
2000年 | 443篇 |
1999年 | 326篇 |
1998年 | 316篇 |
1997年 | 266篇 |
1996年 | 330篇 |
1995年 | 223篇 |
1994年 | 170篇 |
1993年 | 155篇 |
1992年 | 117篇 |
1991年 | 118篇 |
1990年 | 95篇 |
1989年 | 100篇 |
1988年 | 94篇 |
1987年 | 75篇 |
1986年 | 82篇 |
1985年 | 67篇 |
1984年 | 54篇 |
1983年 | 39篇 |
1982年 | 42篇 |
1981年 | 44篇 |
1980年 | 47篇 |
1979年 | 44篇 |
1914年 | 45篇 |
1913年 | 40篇 |
1912年 | 40篇 |
1909年 | 41篇 |
1908年 | 40篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
81.
82.
83.
S. V. Panin I. V. Vlasov V. P. Sergeev B. B. Ovechkin P. O. Marushchak Sunder Ramasubbu P. S. Lyubutin V. V. Titkov 《Physical Mesomechanics》2015,18(3):261-272
The structure and properties of 12Cr1MoV steel irradiated with a zirconium ion beam were studied by optical microscopy, scanning electron microscopy, and micro- and nanoindentation. It is shown that the modification covers the entire cross-section of the irradiated specimens to a depth of 1 mm. The data on irradiation-induced structural changes are used to interpret the changes in mechanical properties of the irradiated specimens under static and cyclic loading. Particular attention is given to analysis of strain estimation by the digital image correlation method. 相似文献
84.
85.
Mihaly Mezei 《Journal of mathematical chemistry》2015,53(10):2184-2190
It is shown that the extent of deviation of a molecular shape from spherical can be characterized by comparing the distribution of the circular variances, a measure originally proposed to quantify angular spread, of the vectors from each atom to the rest of the molecule to the circular variance of a collection of atoms filling the unit sphere. Different measures for quantifying the difference between distribution are proposed and compared. 相似文献
86.
Trehalose is a naturally occurring disaccharide noted for its ability to preserve the biological function of proteins and cell membranes during periods of stress—such as water deprivation or extreme temperature—by stabilizing the conformations of the macromolecules within a glassy matrix. This phenomenon makes use of the propensity for trehalose to interact strongly with protein functional groups and solvent water molecules via hydrogen bonding. Previously, it has been shown that trehalose sugar glasses also support long-range charge transport in oxidation-reduction reactions occurring between spatially separated donors and acceptors. Here, through the use of bulk Arrhenius DC-conductivity measurements, we infer that this anomalously high carrier mobility is due to proton hopping along a hydrogen bonding network formed by sorbed “water wires,” a process known as the Grotthuss mechanism. Additionally, we find that the apparent activation energy of the conductivity depends non-monotonically on the bias voltage. The possibility is raised for novel photovoltaic devices based on the entrapment of photosynthetic proteins within these glasses. 相似文献
87.
Back Cover: Ligand Symmetry Modulation for Designing a Mesoporous Metal–Organic Framework: Dual Reactivity to Transition and Lanthanide Metals for Enhanced Functionalization (Chem. Eur. J. 27/2015) 下载免费PDF全文
88.
Yongjie Zhou Yuqi Mei Tian Luo Wenxue Chen Qiuping Zhong Haiming Chen Weijun Chen 《Molecules (Basel, Switzerland)》2021,26(9)
The contribution of rheological properties and viscoelasticity of the interfacial adsorbed layer to the emulsification mechanism of enzymatic modified sugar beet pectin (SBP) was studied. The component content of each enzymatic modified pectin was lower than that of untreated SBP. Protein and ferulic acid decreased from 5.52% and 1.08% to 0.54% and 0.13%, respectively, resulting in a decrease in thermal stability, apparent viscosity, and molecular weight (Mw). The dynamic interfacial rheological properties showed that the interfacial pressure and modulus (E) decreased significantly with the decrease of functional groups (especially proteins), which also led to the bimodal distribution of particle size. These results indicated that the superior emulsification property of SBP is mainly determined by proteins, followed by ferulic acid, and the existence of other functional groups also promotes the emulsification property of SBP. 相似文献
89.
Zhang Kailun Wu Hongjuan Wang Tian Yao Meng Xie Jixing Jiao Yunhong 《Journal of Thermal Analysis and Calorimetry》2021,145(6):3067-3075
Journal of Thermal Analysis and Calorimetry - A phosphazene-based flame retardant (PBFA) was synthesized by hexachlorocyclotriphosphazene and N-aminoethylpiperazine. To improve the flame retardancy... 相似文献
90.
Urban Larsson Richard J. Nowakowski Carlos P. Santos 《International Journal of Game Theory》2018,47(2):653-671
Combinatorial scoring games, with the property ‘extra pass moves for a player will do him no harm’, are characterized. The characterization involves an order embedding of Conway’s normal play games, and we call our class the universe of Guaranteed scoring games. Also, we give a theorem for comparing guaranteed games with scores (numbers) which extends Ettinger’s work on Dicot scoring games. 相似文献