全文获取类型
收费全文 | 2369篇 |
免费 | 77篇 |
国内免费 | 2篇 |
专业分类
化学 | 1340篇 |
晶体学 | 36篇 |
力学 | 85篇 |
数学 | 144篇 |
物理学 | 843篇 |
出版年
2023年 | 17篇 |
2022年 | 25篇 |
2021年 | 35篇 |
2020年 | 48篇 |
2019年 | 49篇 |
2018年 | 51篇 |
2017年 | 46篇 |
2016年 | 101篇 |
2015年 | 53篇 |
2014年 | 78篇 |
2013年 | 152篇 |
2012年 | 169篇 |
2011年 | 167篇 |
2010年 | 99篇 |
2009年 | 85篇 |
2008年 | 133篇 |
2007年 | 124篇 |
2006年 | 109篇 |
2005年 | 120篇 |
2004年 | 87篇 |
2003年 | 59篇 |
2002年 | 49篇 |
2001年 | 41篇 |
2000年 | 25篇 |
1999年 | 21篇 |
1998年 | 13篇 |
1997年 | 14篇 |
1996年 | 27篇 |
1995年 | 32篇 |
1994年 | 20篇 |
1993年 | 30篇 |
1992年 | 17篇 |
1991年 | 19篇 |
1989年 | 18篇 |
1988年 | 19篇 |
1987年 | 13篇 |
1986年 | 17篇 |
1985年 | 35篇 |
1984年 | 19篇 |
1983年 | 14篇 |
1982年 | 27篇 |
1981年 | 25篇 |
1980年 | 10篇 |
1979年 | 12篇 |
1978年 | 12篇 |
1977年 | 10篇 |
1975年 | 10篇 |
1974年 | 14篇 |
1973年 | 10篇 |
1955年 | 12篇 |
排序方式: 共有2448条查询结果,搜索用时 187 毫秒
1.
Geometriae Dedicata - Given a finite graph of relatively hyperbolic groups with its fundamental group relatively hyperbolic and edge groups quasi-isometrically embedded and relatively quasiconvex... 相似文献
2.
Journal of Algebraic Combinatorics - The symbolic powers, in general, are not equal to the ordinary powers. Therefore, one interesting question here is for what classes of ideals ordinary and... 相似文献
3.
Controlling effective interactions and spatial dispersion of nanoparticles in multiblock copolymer melts 下载免费PDF全文
Debapriya Banerjee Kenneth S. Schweizer 《Journal of Polymer Science.Polymer Physics》2015,53(16):1098-1111
The microscopic Polymer Reference Interaction Site Model theory is employed to study, for the first time, the effective interactions, spatial organization, and miscibility of dilute spherical nanoparticles in non‐microphase separating, chemically heterogeneous, compositionally symmetric AB multiblock copolymer melts of varying monomer sequence or architecture. The dependence of nanoparticle wettability on copolymer sequence and chemistry results in interparticle potentials‐of‐mean force that are qualitatively different from homopolymers. An important prediction is the ability to improve nanoparticle dispersion via judicious choice of block length and monomer adsorption‐strengths which control both local surface segregation and chain connectivity induced packing constraints and frustration. The degree of dispersion also depends strongly on nanoparticle diameter relative to the block contour length. Small particles in copolymers with longer block lengths experience a more homopolymer‐like environment which renders them relatively insensitive to copolymer chemical heterogeneity and hinders dispersion. Larger particles (sufficiently larger than the monomer diameter) in copolymers of relatively short block lengths provide better dispersion than either a homopolymer or random copolymer. The theory also predicts a novel widening of the miscibility window for large particles upon increasing the overall molecular weight of copolymers composed of relatively long blocks. The influence of a positive chi‐parameter in the pure copolymer melt is briefly studied. Quantitative application to fullerenes in specific copolymers of experimental interest is performed, and miscibility predictions are made. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2015 , 53, 1098–1111 相似文献
4.
Das Pritam Kumar Mallik Arnab Kumar Molla Altaf Hossain Santra Apurba Kumar Ganguly Ranjan Saha Abhijit Kumar Sugam Aswal V. K. 《Journal of Thermal Analysis and Calorimetry》2022,147(10):5617-5635
Journal of Thermal Analysis and Calorimetry - Nanofluids have gained recent attention because of their potential applications in diverse engineering fields like enhancing thermal transport,... 相似文献
5.
6.
An Nd:YAG laser-pumped periodically poled RbTiOAsO4 (PPRTA) optical parametric oscillator (OPO) near degeneracy is reported. At a pump power of 3.7 W, a net conversion efficiency of 43% was obtained. These crystals were found to be phase-matchable for the higher order quasi-phase-matched second-harmonic generation (SHG) in the visible range. Detailed analyses of the phase-matching properties for these processes were made by using the published Sellmeier and thermo-optic dispersion formulas. 相似文献
7.
CV Tomy D Pal SS Banerjee S Ramakrishnan AK Grover S Bhattacharya MJ Higgins G Balakrishnan McK Paul 《Pramana》2002,58(5-6):925-935
The weakly pinned single crystals of the hexagonal 2H-NbSe2 compound have emerged as prototypes for determining and characterizing the phase boundaries of the possible order-disorder
transformations in the vortex matter. We present here a status report based on the ac and dc magnetization measurements of
the peak effect phenomenon in three crystals of 2H-NbSe2, in which the critical current densities vary over two orders of magnitude. We sketch the generic vortex phase diagram of
a weakly pinned superconductor, which also utilizes theoretical proposals. We also establish the connection between the metastability
effects and pinning. 相似文献
8.
Steady state temperature distribution in a model Czochralski crucible has been mapped by liquid crystal thermography (LCT).
The crucible is a water-filled glass beaker. Water is used as the test fluid because of ease of experimentation, as well as
the availability of correct thermo-physical properties. In addition, the Prandtl number of water matches those of molten oxides.
A copper cylinder whose diameter is smaller than that of the beaker is placed centrally at the water surface. Convection patterns
are set up by applying constant temperature difference between the crucible wall and the cylinder surface, in the temperature
range of the liquid crystals. The cylinder is given a fixed rotation, thus creating mixed convection conditions in the test
fluid. The LCT images recorded in the present study clearly reveal convective rolls, and the interaction of buoyancy-driven
convection in the crucible with cylinder rotation. The resulting temperature distributions match numerical simulation quite
well. The pure buoyancy and pure rotation experiments result in axisymmetric temperature fields, while in mixed convection,
the field is unsteady and three dimensional. 相似文献
9.
Sunanda Banerjee Rohini M Godbole Sreerup Raychaudhuri Ben Allanach Sunanda Banerjee Satyaki Bhattacharyya Debajyoti Choudhury Siba Prasad Das Anindya Datta Rohini M Godbole Monoranjan Guchait Sabine Kraml Gobinda Majumdar David Miller Margarete Mühlleitner Nobuchika Okada Maxim Perelstein Santosh K Rai Sreerup Raychaudhuri Saurabh D Rindani DP Roy K Sridhar Rishikesh Vaidya D Zeppenfeld 《Pramana》2006,67(4):617-637
This is summary of the activities of the working group on collider physics in the IXth Workshop on High Energy Physics Phenomenology
(WHEPP-9) held at the Institute of Physics, Bhubaneswar, India in January 2006. Some of the work subsequently done on these
problems by the subgroups formed during the workshop is included in this report. 相似文献
10.
The time delay experiment proposed by I.I. Shapiro in 1964 and conducted in the seventies was the most precise experiment
of general relativity until that time. Further experimentation has improved the accuracy level of both the time delay and
the light deflection experiments. A simulation model is proposed that involves only a simple mass and time transformation
factor involving velocity of light. The light deflection and the time delay experiments are numerically simulated using this
model that does not use the general relativistic equations. The computed values presented in this paper compare well with
recent levels of accuracy of their respective experimental results. 相似文献