全文获取类型
收费全文 | 126篇 |
免费 | 12篇 |
国内免费 | 15篇 |
专业分类
化学 | 83篇 |
晶体学 | 3篇 |
力学 | 6篇 |
综合类 | 1篇 |
数学 | 20篇 |
物理学 | 40篇 |
出版年
2024年 | 1篇 |
2023年 | 3篇 |
2022年 | 6篇 |
2021年 | 7篇 |
2020年 | 7篇 |
2019年 | 5篇 |
2018年 | 6篇 |
2017年 | 12篇 |
2016年 | 2篇 |
2015年 | 6篇 |
2014年 | 1篇 |
2013年 | 8篇 |
2012年 | 15篇 |
2011年 | 12篇 |
2010年 | 8篇 |
2009年 | 10篇 |
2008年 | 8篇 |
2007年 | 7篇 |
2006年 | 10篇 |
2005年 | 4篇 |
2004年 | 2篇 |
2003年 | 3篇 |
2002年 | 1篇 |
2001年 | 1篇 |
1998年 | 1篇 |
1996年 | 1篇 |
1994年 | 1篇 |
1992年 | 1篇 |
1991年 | 3篇 |
1987年 | 1篇 |
排序方式: 共有153条查询结果,搜索用时 15 毫秒
1.
Yabin Zhou Shifeng Wang Yinxi Zhang Yong Zhang 《Journal of Polymer Science.Polymer Physics》2006,44(8):1226-1236
Methacrylic acid (MAA) was used as in situ surface modifier to improve the interface interaction between nano‐CaCO3 particle and ethylene–propylene–diene monomer (EPDM) matrix, and hence the mechanical properties of nano‐CaCO3‐filled EPDM vulcanizates. The results showed that the incorporation of MAA improved the filler–matrix interaction, which was proved by Fourier transformation infrared spectrometer (FTIR), Kraus equation, crosslink density determination, and scanning electron microscope (SEM). The formation of carboxylate and the participation of MAA in the crosslinking of EPDM indicated the strong filler–matrix interaction from the aspect of chemical reaction. The results of Kraus equation showed that the presence of MAA enhanced the reinforcement extent of nano‐CaCO3 on EPDM vulcanizates. Crosslink density determination proved the formation of the ionic crosslinks in EPDM vulcanizates with the existence of MAA. The filler particles on tensile fracture were embedded in the matrix and could not be observed obviously, indicating that a strong interfacial interaction between the filler and the matrix had been achieved with the incorporation of MAA. Meanwhile, the presence of MAA remarkably increased the modulus and tensile strength of the vulcanizates, without negative effect on the high elongation at break. Furthermore, the ionic bond was thought to be formed only on filler surface because of the absolute deficiency of MAA, which resulted in the possible structure where filler particles were considered as crosslink points. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 1226–1236, 2006 相似文献
2.
Weifu Dong Piming Ma Shifeng Wang Mingqing Chen Xiaoxia Cai Yong Zhang 《Polymer Degradation and Stability》2013
Poly(β-hydroxybutyrate) (PHB) is a bio-based and biodegradable aliphatic polyester, however its application is limited by some disadvantages such as high price, brittleness, poor processability and low melt-strength due to serious thermal degradation. Partial crosslinking initiated by dicumyl peroxide (DCP) was applied in this work to improve the performance of poly(β-hydroxybutyrate)/poly(d,l-lactic acid) (PHB/PDLLA) blends. The partial crosslinking of the blends and its effect on the properties, morphology, rheology and thermal behavior of the blends were investigated. The tensile strength and impact toughness of the PHB were increased by incorporation of the PDLLA, which were improved further after the partial crosslinking because of an increased compatibility between the PHB and the PDLLA phases. The rheological study revealed that the storage modulus (G′) and complex viscosity (η*) of the blends were increased after addition of the DCP. On the other hand, the crystallization of PHB in the blends was restricted to a certain extent by the formation of partially crosslinked network while its crystal form was not modified. 相似文献
3.
Liu Kang Wang Rujing Zheng Shijian Dong Shifeng Sun Guowei 《Nonlinear dynamics》2022,107(3):2363-2390
Nonlinear Dynamics - This study focuses on the design of a fixed-time disturbance observer-based robust fault-tolerant tracking control scheme for an uncertain quadrotor unmanned aerial vehicle... 相似文献
4.
基于Lagoudas形状记忆合金(SMA)三维本构模型,假设材料为各向同性,推导了SMA平面应力状态的增量型本构方程,继而编写了ABAQUS用户自定义材料(UMAT)子程序,研究了在双向拉伸情况下,外载荷、温度、椭圆孔口长短轴之比对超弹性SMA椭圆孔口板中应力诱发马氏体相变区的影响。数值结果表明:应力诱发马氏体相变首先发生在椭圆孔口长轴端点部位,在外加载荷作用下逐渐扩展到板内,并由内向外形成马氏体相区、相变混合区和奥氏体相区;SMA板内应力诱发马氏体完全相变区面积与施加外载荷成正相关,与温度成负相关;随着椭圆孔口长短轴之比增大,SMA板内应力诱发马氏体完全相变区面积呈现出先减小后增大的趋势;拉应力差值相同时,相较于拉应力沿椭圆孔口长轴方向较大的情况,当拉应力沿椭圆孔口短轴方向较大时,SMA板内完全相变区面积较大,椭圆孔口周边应力集中现象更明显。 相似文献
5.
6.
搜索区传递2-(q,4,1)设计 总被引:1,自引:0,他引:1
对于区传递但非旗传递的可解2-(q,4,1)设计,Camina指出,当q=13,37,61,109,157,181时有具体的例子,但是否有更多的q产生具体例子有待研究。主要结果:设q是素数幂且q=13(mod24),则对于每个q〈2000,总存在区传递但非旗传递的2-(q,4,1)设计。 相似文献
7.
采用Gadelle-Defaye法制备了全-6-氨基-β-环糊精[β-CD-(NH2)7],并用"Grafting-from"接枝法得到不同分子量的星型结构β-环糊精-g-聚L-谷氨酸(β-CD-g-PLGA).对β-CD-g-PLGA进行酰肼化改性后与醛基化海藻酸钠(ALG-CHO)通过席夫碱交联反应制备β-CD-g-PLGA/ALG水凝胶.研究了前驱体浓度以及β-CD-gPLGA分子量对β-CD-g-PLGA/ALG水凝胶性能的影响,并以疏水性辛伐他汀(SIM)为模型药物,研究了水凝胶对SIM的控制释放行为. 相似文献
8.
Fu H Pang S Xue P Yang J Liu X Wang Y Li T Li H Li X 《Applied biochemistry and biotechnology》2011,165(2):465-475
Fibroblast growth factor-21 (FGF21) is a hepatic hormone that plays a critical role in metabolism, stimulating fatty acid
oxidation in the liver and glucose uptake in adipose tissue. In this study, we produced tobacco plants expressing human recombinant
FGF21 (hFGF21) via Agrobacterium-mediated transformation using a potato virus X (PVX)-based vector (pgR107). The vector contained the sequence encoding the
human FGF21 gene fused with green florescence protein and a histidine tag. The recombinant plasmid was introduced into leaf
cells of Nicotiana benthamiana (a wild Australian tobacco) via Agrobacterium-mediated agroinfiltration. As determined by fluorescence and Western blot of leaf extracts, the hFGF21 gene was correctly
translated in tobacco plants. Seven days after agroinfection, the recombinant hFGF21 had accumulated to levels as high as
450 μg g−1 fresh weight in leaves of agroinfected plants. The recombinant hFGF21 was purified from plant tissues by Ni–NTA affinity
chromatography, and the purified hFGF21 stimulated glucose uptake in 3T3/L1 cells. This indicated that the recombinant hFGF21
expressed via the PVX viral vector in N. benthamiana was biologically active. 相似文献
9.
A methoxypoly(ethylene glycol)-block-poly(α,L-glutamic acid) (mPEGGA) diblock copolymer is synthesized. Using QCM measurements, it is shown that (CS/mPEGGA)(n) film construction takes place over two build-up stages (exponential-to-linear). UV-vis spectra reveal the regular increase of the multilayer film growth at different molecular weights of mPEGGA. Contact angle and surface morphology investigation prove that the hydrophilicity of CS/mPEGGA multilayer film-modified substrate becomes better and the surface becomes rough. Significantly reduced cell adhesion is observed on the CS/mPEGGA multilayer film coated surface. 相似文献
10.
Shifeng Xiong 《Journal of multivariate analysis》2011,102(2):336-348
This paper provides an asymptotics look at the generalized inference through showing connections between the generalized inference and two widely used asymptotic methods, the bootstrap and plug-in method. A generalized bootstrap method and a generalized plug-in method are introduced. The generalized bootstrap method can not only be used to prove asymptotic frequentist properties of existing generalized confidence regions through viewing fiducial generalized pivotal quantities as generalized bootstrap variables, but also yield new confidence regions for the situations where the generalized inference is unavailable. Some examples are presented to illustrate the method. In addition, the generalized F-test (Weerahandi, 1995 [26]) can be derived by the generalized plug-in method, then its asymptotic validity is obtained. 相似文献