全文获取类型
收费全文 | 6077篇 |
免费 | 1048篇 |
国内免费 | 779篇 |
专业分类
化学 | 4176篇 |
晶体学 | 42篇 |
力学 | 445篇 |
综合类 | 33篇 |
数学 | 757篇 |
物理学 | 2451篇 |
出版年
2024年 | 8篇 |
2023年 | 127篇 |
2022年 | 156篇 |
2021年 | 178篇 |
2020年 | 219篇 |
2019年 | 235篇 |
2018年 | 173篇 |
2017年 | 179篇 |
2016年 | 264篇 |
2015年 | 290篇 |
2014年 | 292篇 |
2013年 | 357篇 |
2012年 | 531篇 |
2011年 | 595篇 |
2010年 | 399篇 |
2009年 | 319篇 |
2008年 | 421篇 |
2007年 | 376篇 |
2006年 | 358篇 |
2005年 | 333篇 |
2004年 | 281篇 |
2003年 | 196篇 |
2002年 | 175篇 |
2001年 | 146篇 |
2000年 | 109篇 |
1999年 | 149篇 |
1998年 | 106篇 |
1997年 | 118篇 |
1996年 | 126篇 |
1995年 | 116篇 |
1994年 | 82篇 |
1993年 | 67篇 |
1992年 | 58篇 |
1991年 | 65篇 |
1990年 | 67篇 |
1989年 | 53篇 |
1988年 | 41篇 |
1987年 | 27篇 |
1986年 | 34篇 |
1985年 | 27篇 |
1984年 | 14篇 |
1983年 | 9篇 |
1982年 | 11篇 |
1981年 | 5篇 |
1980年 | 5篇 |
1979年 | 1篇 |
1976年 | 2篇 |
1974年 | 1篇 |
1957年 | 3篇 |
排序方式: 共有7904条查询结果,搜索用时 15 毫秒
991.
Thai Thuan Quang Lien Vuong Lam Nguyen Van Dai 《Complex Analysis and Operator Theory》2013,7(1):237-259
The aim of this paper is to give some criterions for holomorphy of F-valued σ(F, W)-holomorphic functions which are bounded on bounded sets in a domain D of Fréchet spaces E (resp. ${\mathbb{C}^n}$ ) where ${W \subset F'}$ defines the topology of Fréchet space F. Base on these results we consider the problem on holomorphic extension of F-valued σ(F, W)-holomorphic functions from non-rare subsets of D and from subsets of D which determines uniform convergence in H(D). As an application of the above, some theorems of Vitali-type for a locally bounded sequence ${\{f_i\}_{i \in \mathbb{N}}}$ of Fréchet-valued holomorphic functions are also proved. 相似文献
992.
993.
In this paper, we consider the existence and multiplicity of solutions for a class of nonlinear impulsive problem on the half-line. By using a variational method and a variant fountain theorem, we obtain some new criteria to guarantee that the impulsive problem has at least one solution and infinitely many solutions respectively. We extend and improve some recent results. 相似文献
994.
Chongxin Yin Min Wang Qingzhi Ma Huiyang Bian Hao Ren Hongqi Dai Jinlan Cheng 《Molecules (Basel, Switzerland)》2021,26(14)
Rice straw hydrotropic lignin was extracted from p-Toluene sulfonic acid (p-TsOH) fractionation with a different combined delignification factor (CDF). Hydrotropic lignin characterization was systematically investigated, and alkaline lignin was also studied for the contrast. Results showed that the hydrotropic rice straw lignin particle was in nanometer scopes. Compared with alkaline lignin, the hydrotropic lignin had greater molecular weight. NMR analysis showed that β-aryl ether linkage was well preserved at low severities, and the unsaturation in the side chain of hydrotropic lignin was high. H units and G units were preferentially degraded and subsequently condensed at high severity. High severity also resulted in the cleavage of part β-aryl ether linkage. 31P-NMR showed the decrease in aliphatic hydroxyl groups and the increasing carboxyl group content at high severity. The maximum weight loss temperature of the hydrotropic lignin was in the range of 330–350 °C, higher than the alkaline lignin, and the glass conversion temperature (Tg) of the hydrotropic lignin was in the range of 107–125 °C, lower than that of the alkaline lignin. The hydrotropic lignin has high β-aryl ether linkage content, high activity, nanoscale particle size, and low Tg, which is beneficial for its further valorization. 相似文献
995.
Xiongping Dai 《Journal of Difference Equations and Applications》2013,19(6):561-587
The theory of Liao standard systems of difference equations for discrete differentiable dynamical systems over compact manifolds has been developed. Some relations between the topological structures of their phase portraits and that of their corresponding linear systems have been presented as well. 相似文献
996.
A nonstandard finite difference scheme is developed to solve an initial-boundary value problem involving a quartic nonlinearity that arises in heat transfer with thermal radiation. Not only does the scheme satisfy the positivity condition, but it is also stable for large values of the equation parameters. 相似文献
997.
Hongshuai Dai 《Journal of Theoretical Probability》2013,26(3):676-696
In this paper, we provide two approximations in law of operator fractional Brownian motions. One is constructed by Poisson processes, and the other generalizes a result of Taqqu (Z. Wahrscheinlichkeitstheor. Verw. Geb. 31:287–302, 1975). 相似文献
998.
Size effects on tensile and fatigue behaviour of polycrystalline metal foils at the micrometer scale
Tensile and fatigue properties of as-rolled and annealed polycrystalline Cu foils with different thicknesses at the micrometer scale were investigated. Uniaxial tensile testing results showed that with decreasing foil thickness the uniform elongation decreases for both as-rolled and annealed foils, whereas the yield strength and ultimate tensile strength increase for as-rolled foils, but decrease for the annealed foils. For both the as-rolled or annealed foils, bending fatigue resistance decreases with decreasing the foil thickness. Deformation and fatigue damage behaviour of the free-standing foils were characterised as a function of foil thickness. In addition, the fatigue strength of various small-scale Cu foils was compared to understand the physical mechanisms of size effects on mechanical properties of the metallic material at micrometer scales. 相似文献
999.
T. Battumur Swapnil B. Ambade Rohan B. Ambade Pashupati Pokharel Dai Soo Lee Sung-Hwan Han Wonjoo Lee Soo-Hyoung Lee 《Current Applied Physics》2013,13(1):196-204
In order to enhance the capacitance of electrochemical capacitors, multiwalled carbon nanotubes (MWCNTs) and graphene nanosheets (GNS) were added to cobalt oxide (Co3O4) paste. The composite film based on Co3O4/MWCNT/GNS (95:4:1 wt%) exhibited a capacitance of 294 F/g while the capacitance of Co3O4/MWCNT (95:5 wt%) and pure Co3O4 film is 205 and 163 F/g, respectively. The enhanced capacitance of Co3O4/MWCNT/GNS composite film was attributed to the electrochemical contributions of the Co3O4 nanoparticle attached to the GNS as well as their significantly increased specific surface areas by MWCNTs. Furthermore, the composite films showed faradaic redox capacitive behavior to double-layer capacitive behavior due to the different nanostructures of the composites. 相似文献
1000.