全文获取类型
收费全文 | 1250篇 |
免费 | 163篇 |
国内免费 | 127篇 |
专业分类
化学 | 882篇 |
晶体学 | 9篇 |
力学 | 70篇 |
综合类 | 9篇 |
数学 | 185篇 |
物理学 | 385篇 |
出版年
2024年 | 7篇 |
2023年 | 26篇 |
2022年 | 37篇 |
2021年 | 39篇 |
2020年 | 41篇 |
2019年 | 45篇 |
2018年 | 40篇 |
2017年 | 31篇 |
2016年 | 69篇 |
2015年 | 49篇 |
2014年 | 57篇 |
2013年 | 74篇 |
2012年 | 95篇 |
2011年 | 116篇 |
2010年 | 75篇 |
2009年 | 81篇 |
2008年 | 80篇 |
2007年 | 66篇 |
2006年 | 77篇 |
2005年 | 46篇 |
2004年 | 48篇 |
2003年 | 41篇 |
2002年 | 24篇 |
2001年 | 18篇 |
2000年 | 31篇 |
1999年 | 39篇 |
1998年 | 22篇 |
1997年 | 25篇 |
1996年 | 20篇 |
1995年 | 10篇 |
1994年 | 19篇 |
1993年 | 16篇 |
1992年 | 15篇 |
1991年 | 11篇 |
1990年 | 9篇 |
1989年 | 9篇 |
1988年 | 7篇 |
1987年 | 1篇 |
1986年 | 2篇 |
1985年 | 6篇 |
1984年 | 2篇 |
1983年 | 1篇 |
1982年 | 3篇 |
1980年 | 2篇 |
1979年 | 1篇 |
1978年 | 1篇 |
1977年 | 1篇 |
1976年 | 1篇 |
1975年 | 1篇 |
1973年 | 3篇 |
排序方式: 共有1540条查询结果,搜索用时 31 毫秒
141.
Tingxiu Xie Hongzhi Liu Yuchun Ou Guisheng Yang 《Journal of Polymer Science.Polymer Physics》2005,43(22):3213-3221
The microstructure, impact strength, and rheological properties of blends consisting of high‐density polyethylene (HDPE) and maleated poly (ethylene‐octene) (POEg) and/or calcium carbonate (CaCO3) were investigated. The improvement of impact strength of HDPE/POEg was limited due to the high miscibility between them. The introduction of CaCO3 had a negative impact on the toughness of the matrix because of the poor interfacial adhesion. In ternary blends of HDPE/POEg/CaCO3, an elastomer layer was formed around CaCO3 particles due to the strong interaction between POEg and CaCO3, which improves the HDPE‐CaCO3 interfacial strength and the toughness of the blends. A significant enhancement of dynamic viscosity, storage modulus, and the low‐shear viscosity were observed as the results of the high miscibility of HDPE with POEg and strong interaction between POEg and CaCO3. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 3213–3221, 2005 相似文献
142.
143.
StudiesontheCrystallizationBehaviorofPolypropyleneSolidPhaseGraftedMaleicAnhydrideStudiesontheCrystallizationBehaviorofPolypr... 相似文献
144.
Cheng‐Fang Ou 《Journal of Polymer Science.Polymer Physics》2003,41(22):2902-2910
Poly(trimethylene terephthalate) (PTT)/montmorillonite (MMT) nanocomposites were prepared by the solution intercalation method. Two different kinds of clay were organomodified with an intercalation agent of cetyltrimetylammonium chloride (CMC). X‐ray diffraction (XRD) indicated that the layers of MMT were intercalated by CMC, and interlayer spacing was a function of the cationic exchange capacity of clay. The XRD studies demonstrated that the interlayer spacing of organoclay in the nanocomposites depends on the amount of organoclay. From the results of differential scanning calorimetric analysis, it was found that clay behaves as a nucleating agent and enhances the crystallization rate of PTT. The maximum enhancement of the crystallization rate for the nanocomposites was observed in nanocomposites containing about 1 wt % organoclay with a range of 1–15 wt %. From thermogravimetric analysis, we found that the thermal stability of the nanocomposites was enhanced by the addition of 1–10 wt % organoclay. According to transmission electron microscopy, the organoclay particle was highly dispersed in the PTT matrix without a large agglomeration of particles for a low organoclay content (5 wt %). However, an agglomerated structure did form in the PTT matrix at a 15 wt % organoclay content. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 2902–2910, 2003 相似文献
145.
J. J. Yang L. Lee M. Jansen M. Sergant S. S. Ou J. Wilcox 《Fiber and Integrated Optics》1988,7(3):217-228
Surface emitting lasers are of interest for various applications such as monolithic two-dimensional arrays and optical interconnects for integrated optics. Moreover, surface emitting lasers offer the advantage of wafer processing and testing. Several approaches for achieving surface emission are described. In addition, TRW s fabrication of a large monolithic two dimensional array of GaAs/AlGaAs surface emitting lasers which contains a total of 100 lasers is reported. 相似文献
146.
The suitability of ormosils as photonic materials was investigated. Vinyl and phenyl silicates were synthesised below 100°C. A detailed assignment of mid-infrared vibrational absorption bands is given. This allowed assignment of overtone and combination bands in the near-infrared region and an assessment of residual water contamination, which is low and can be expelled by evacuation. These ormosils have low intrinsic and extrinsic optical absorption in the visible spectral region and at useful wavelengths in the near-infrared. 相似文献
147.
3,4-disubstituted furans are converted into gamma-hydroxy-butenolides by treatment with NaClO(2) in aqueous EtOH containing NaH(2)PO(4). 相似文献
148.
Suppose that is the set of connected graphs such that a graph G if and only if G satisfies both (F1) if X is an edge cut of G with |X|3, then there exists a vertex v of degree |X| such that X consists of all the edges incident with v in G, and (F2) for every v of degree 3, v lies in a k-cycle of G, where 2k3.In this paper, we show that if G and (G)3, then for every pair of edges e,fE(G), G has a trail with initial edge e and final edge f which contains all vertices of G. This result extends several former results. 相似文献
149.
JunShuai Xue Yue Hao XiaoWei Zhou JinCheng Zhang ChuanKai Yang XinXiu Ou LinYu Shi Hao Wang LinAn Yang JinFeng Zhang 《Journal of Crystal Growth》2011,314(1):359-364
High quality InAlN/GaN heterostructures are successfully grown on the (0 0 0 1) sapphire substrate by pulsed metal organic chemical vapor deposition. The InAlN barrier layer with an indium composition of 17% is observed to be nearly lattice matched to GaN layer, and a smooth surface morphology can be obtained with root mean square roughness of 0.3 nm and without indium droplets and phase separation. The 50 mm InAlN/GaN heterostructure wafer exhibits a mobility of 1402 cm2/V s with a sheet carrier density of 2.01×1013 cm?2, and a low average sheet resistance of 234 Ω/cm2 with a sheet resistance nonuniformity of 1.22%. Compared with the conventional continual growth method, PMOCVD reduces the growth temperature of the InAlN layer and the Al related prereaction in the gas phase, and consequently enhances the surface migration, and improves the crystallization quality. Furthermore, indium concentration of InAlN layer can be controlled by adjusting the pulse time ratio of TMIn to TMAl in a unit cycle, the growth temperature and pressure, as well as the InAlN layer thickness by the number of unit cycle repeats. 相似文献
150.