全文获取类型
收费全文 | 650篇 |
免费 | 15篇 |
国内免费 | 5篇 |
专业分类
化学 | 416篇 |
晶体学 | 16篇 |
力学 | 26篇 |
数学 | 46篇 |
物理学 | 166篇 |
出版年
2023年 | 6篇 |
2022年 | 30篇 |
2021年 | 32篇 |
2020年 | 23篇 |
2019年 | 25篇 |
2018年 | 21篇 |
2017年 | 22篇 |
2016年 | 27篇 |
2015年 | 17篇 |
2014年 | 31篇 |
2013年 | 56篇 |
2012年 | 30篇 |
2011年 | 53篇 |
2010年 | 29篇 |
2009年 | 19篇 |
2008年 | 16篇 |
2007年 | 16篇 |
2006年 | 17篇 |
2005年 | 11篇 |
2004年 | 10篇 |
2003年 | 11篇 |
2002年 | 8篇 |
2001年 | 6篇 |
2000年 | 6篇 |
1999年 | 7篇 |
1998年 | 4篇 |
1997年 | 6篇 |
1996年 | 5篇 |
1995年 | 4篇 |
1994年 | 10篇 |
1993年 | 4篇 |
1992年 | 5篇 |
1991年 | 5篇 |
1990年 | 12篇 |
1989年 | 15篇 |
1988年 | 2篇 |
1986年 | 4篇 |
1985年 | 6篇 |
1984年 | 8篇 |
1982年 | 4篇 |
1981年 | 8篇 |
1980年 | 6篇 |
1979年 | 2篇 |
1977年 | 4篇 |
1976年 | 2篇 |
1975年 | 3篇 |
1974年 | 4篇 |
1972年 | 3篇 |
1970年 | 2篇 |
1966年 | 2篇 |
排序方式: 共有670条查询结果,搜索用时 15 毫秒
71.
N. A. Hussein A. Shukri A. A. Tajuddin C. S. Chong 《Radiation Physics and Chemistry》2004,71(6):1077-1086
Osteoporosis is a bone condition that is caused mainly by the degradation of trabecular and cortical bone resulting in the decrease of bone strength and eventually leads to bone fracture. A low angle X-ray scattering (LAXS) system that uses mainly the coherent scattering process for the characterisation of materials was constructed to study such bone conditions. Several finger phantoms were fabricated to simulate bone of varying densities. The LAXS method was able to identify the changes in bone density quite well by comparing energy dispersive X-ray diffraction patterns as well as the angular patterns. Quantitative information can be extracted from such patterns that relate to bone loss. Signature patterns at low exposure times were produced in order to reduce the dose received with reasonable identification power but at slightly higher statistical errors compared with long exposure patterns. Use of other parameters to increase the sensitivity was attempted. 相似文献
72.
Hussein M. Etmimi Matthew P. Tonge Ronald D. Sanderson 《Journal of polymer science. Part A, Polymer chemistry》2011,49(7):1621-1632
Graphite oxide (GO) was prepared and immobilized with dodecyl isobutyric acid trithiocarbonate (DIBTC) reversible addition‐fragmentation chain transfer (RAFT) agent. The hydroxyl groups of GO were attached to the DIBTC RAFT agent through an esterification process. The resultant modified GO was used for the preparation of polystyrene (PS)/graphite nanocomposites in miniemulsion polymerization. The RAFT‐grafted GO (GO‐DIBTC) at various loadings was dispersed in styrene monomer, and the resultant mixtures were sonicated in the presence of a surfactant (sodium dodecylbenzene sulfonate) and a hydrophobe (hexadecane) to form miniemulsions. The stable miniemulsions thus obtained were polymerized using azobisisobutyronitrile as the initiator to yield encapsulated PS‐GO nanocomposites. The molar mass and polydispersity index of PS in the nanocomposites depended on the amount of RAFT‐grafted GO in the system, in accordance with the features of the RAFT polymerization method. The PS‐GO nanocomposites were of exfoliated morphology, as confirmed by X‐ray diffraction and transmission electron microscopy measurements. The thermal stability and mechanical properties of the PS‐GO nanocomposites were better than those of the neat PS polymer. Furthermore, the mechanical properties were dependent on the modified GO content (i.e., the amount of RAFT‐grafted GO). © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011 相似文献
73.
74.
H. El-Samman A. Hussein S. Hassan 《Journal of Radioanalytical and Nuclear Chemistry》2010,285(2):259-262
A well performance Electrolytic Controlled Etching (ECE) unit has been designed and constructed in our laboratory. Low electric
field strength of few volts and a 2 kHz wave signals has been applied across the electrodes that confined the 9 and 12 μm
thick PET foils in the ECE unit. PET foils were exposed to fission fragments (FFS) using 252Cf source. The dependence of different measurable parameters such as FFS fluence (Φ), applied voltage (V), etching temperature (T) and etching concentration (C) on both track etch rate (V
T) and breakthrough time (T
B) have extensively been studied using the FFS-irradiated PET foils. Various empirical relationships connecting the results of the present work have been extracted. Moreover,
the constructed ECE technique has proven to be an encouraged time saving method in the development of trusting measurements
comparing with others that might involve expensive sophisticated tools. 相似文献
75.
76.
The hypothesis of the ulti-peripheral odel is extended to the hadron –nucleus interactions and then generalized to the nucleus –nucleus case. The processing of the odel depends on input parameters that are extracted fro the features of the experiments in this .eld.The number of encountered nucleons from both target and projectile are estimated according to the eikonal scattering approach.The screening effect due to the interaction of the projectile nucleons in successive manner with the target nucleus is considered.The rapidity distributions of fast particles are reproduced for the successive collisions in p –S and 32 S –32 S interactions at 200 A GeV.A global fair agreement is found in comparison with data of the experi ent CERN-NA-035. 相似文献
77.
A.SH. Hussein Z. Hassan S.M. Thahab Abu Hassan M.A. Abid C.W. Chin 《Physica B: Condensed Matter》2011,406(6-7):1267-1271
We have studied the structural properties of undoped and Si-doped AlxGa1?xN/GaN/AlN on Si (1 1 1) substrate prepared by plasma-assisted molecular beam epitaxy (PA-MBE) using high-resolution X-ray diffraction (HR-XRD) and atomic force microscopy (AFM). In comparison with undoped AlGaN, the roughness and dislocation density on the surface of the AlGaN layer decrease with Si doping. Full width half maximum (FWHM) of the undoped and Si-doped samples were equal to 0.69° and 0.52°, respectively. This indicates that the Si doping improves the crystalline quality of the AlxGa1?xN layer compared with the undoped one. Raman scattering measurement reveals that the optical phonon modes of A1(LO) and E2(H) of the AlGaN show a one-mode and two-modes behavior, respectively. The Fourier-transform infrared reflectance (FTIR) investigation confirms the one-mode (two-mode) behavior of the LO (TO) phonon in our samples. This is in good agreement with Raman measurement. Finally, the barrier height (ΦB) of undoped and Si-doped AlxGa1?xN samples was found to be 0.86 and 0.74 eV, respectively. 相似文献
78.
So-called “quantized” algebras are popular objects of study in non-commutative algebra. Usually such algebras are either positively graded Ore domains R with R 0 = K a field and R = K[R 1], R 1 being a finite dimensional K vectorspace, or else filtered rings having a ring of forementioned type for its associated graded ring. We show that every discrete valuation of K extends to a valuation, in the sence of O. Schilling (cf. [S]), of the skewfield of fractions, Δ = Qcl (R), of the Ore domain R (Proposition 2.3. and Corollary 2.8.). Such extension property has long been known to fail for finite dimensional skewfields over K; its validity in the case of several quantized algebras may be viewed as a consequence of the rigidity of their defining relations. Our result opens the door for a more arithmetical study of Δ e.g. in case K is a numberfield or an algebraic function field of a curve; for an application in this direction we refer to a first version of some divisor calculus started in [VW]. 相似文献
79.
80.
Polu Anji Reddy Kareem Aseel A. Rasheed Hussein Kh. 《Journal of Solid State Electrochemistry》2023,27(2):409-416
Journal of Solid State Electrochemistry - In the present study, we report the synthesis and characterisation of solid polymer electrolytes (SPEs) based on polymer poly(ethylene oxide) (PEO), salt... 相似文献