全文获取类型
收费全文 | 210280篇 |
免费 | 2252篇 |
国内免费 | 724篇 |
专业分类
化学 | 118523篇 |
晶体学 | 3381篇 |
力学 | 8129篇 |
综合类 | 4篇 |
数学 | 21125篇 |
物理学 | 62094篇 |
出版年
2016年 | 2528篇 |
2015年 | 1967篇 |
2014年 | 2677篇 |
2013年 | 8466篇 |
2012年 | 5899篇 |
2011年 | 7465篇 |
2010年 | 4860篇 |
2009年 | 4745篇 |
2008年 | 6775篇 |
2007年 | 6948篇 |
2006年 | 6728篇 |
2005年 | 6302篇 |
2004年 | 5727篇 |
2003年 | 5081篇 |
2002年 | 4873篇 |
2001年 | 5963篇 |
2000年 | 4573篇 |
1999年 | 3674篇 |
1998年 | 2902篇 |
1997年 | 2975篇 |
1996年 | 2971篇 |
1995年 | 2685篇 |
1994年 | 2550篇 |
1993年 | 2439篇 |
1992年 | 2927篇 |
1991年 | 2803篇 |
1990年 | 2745篇 |
1989年 | 2756篇 |
1988年 | 2709篇 |
1987年 | 2731篇 |
1986年 | 2512篇 |
1985年 | 3514篇 |
1984年 | 3498篇 |
1983年 | 2877篇 |
1982年 | 3148篇 |
1981年 | 3032篇 |
1980年 | 2995篇 |
1979年 | 3100篇 |
1978年 | 3337篇 |
1977年 | 3166篇 |
1976年 | 3075篇 |
1975年 | 2902篇 |
1974年 | 2844篇 |
1973年 | 2859篇 |
1972年 | 1821篇 |
1971年 | 1538篇 |
1968年 | 1961篇 |
1967年 | 2157篇 |
1966年 | 1951篇 |
1965年 | 1520篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
91.
92.
K. Morigaki K. Takeda H. Hikita C. Ogihara P. Roca i Cabarrocas 《Journal of Non》2008,354(19-25):2131-2134
Our model for light-induced defect creation in hydrogenated amorphous silicon is applied to its kinetics, i.e., the growing curve of light-induced dangling bond density as a function of illumination time, which is fitted to a stretched exponential function. Two parameters β and τ involved in the function are estimated as functions of saturated dangling bond density in terms of our model. These are compared with two experimental results, i.e., our results obtained from ESR measurements and Shimakawa et al.’s results obtained from photoconductivity measurements. The saturated dangling bond density is also measured as a function of the generation rate of free carriers. The experimental results are compared with calculated results and discussed. 相似文献
93.
J. Song H. Jiang Z.J. Liu D.Y. Khang Y. Huang J.A. Rogers C. Lu C.G. Koh 《International Journal of Solids and Structures》2008,45(10):3107-3121
A finite-deformation theory is developed to study the mechanics of thin buckled films on compliant substrates. Perturbation analysis is performed for this highly nonlinear system to obtain the analytical solution. The results agree well with experiments and finite element analysis in wavelength and amplitude. In particular, it is found that the wavelength depends on the strain. Based on the accurate wavelength and amplitude, the membrane and peak strains in thin films, and stretchability and compressibility of the system are also obtained analytically. 相似文献
94.
95.
This paper considers a receiver set partitioning and sequencing problem in a wavelength division multiplexing single-hop lightwave network for multicasting traffic. The problem is analysed in the approach of uncapacitated single batch-processing machine scheduling. In the analysis, several solution properties are characterized with respect to a mean flow time measure, based upon which two heuristic algorithms are developed, along with a dynamic programming algorithm. Several numerical experiments show that the heuristic algorithms generate good schedules. The problem is extended to consider two measures simultaneously including the mean flow time and the number of transmissions, for which the proposed algorithms also perform well. 相似文献
96.
M. R. McEwen J. P. Sephton P. H. G. Sharpe D. R. Shipley 《Radiation Physics and Chemistry》2003,68(6):1017-1022
A phantom composed of alanine dosimeter material has been constructed and depth–dose measurements made in a 10 MeV electron beam. The results have demonstrated the feasibility of using relative depth–dose measurements to determine stopping power ratios in materials of dosimetric interest. Experimental stopping power ratios for alanine dosimeter material and water agreed with the data of ICRU Report 37 within the uncertainty of the experiment (±1.2% at a 95% confidence level). 相似文献
97.
The pumiceous products of the large-scale explosive eruptions at Santorini show a high grade of similarity in their optical
appearance as well as in their chemical composition. The demand for a clear classification of these eruption products was
raised from archaeological research, where pumice can be interpreted as a “post-eruption” time marker. The aim of this work
was to find elements that underwent significant changes because of geochemical processes and that could be indicative for
a distinction of pumice produced by the five major explosive eruptions. INAA of 25 elements allows a clear classification
and contributes new information to the chemical evolution of Santorini volcano.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
98.
Feel like writing a review for The Mathematical Intelligencer? You are welcome to submit an unsolicited review of a book of your choice; or, if you would welcome being assigned a book to review, please write us, telling us your expertise and your predilections. 相似文献
99.
A MCSCF-method for minimization of the variance yielding an optimal basisset of variance minimizing orbitals in analogy to Löwdin's natural orbitals for minimal energy is developed. 相似文献
100.
This paper proposes and analyzes a GaAs traveling-wave optical modulator which uses a modulated coplanar strip electrode with periodic cross-tie overlay. This slow-wave structure can be designed to satisfy phase velocity and impedance matching conditions simultaneously. The dominant conductor loss in the slow-wave structure is reduced using the modulated coplanar strip electrode. The calculated 3-dB modulation bandwidth (100 GHz) is much wider than the bandwidth limit (30 GHz) of conventional electrode structures that are limited by phase velocity mismatch.This work was supported by the U.S. Army Research Office under contract DAAL-03-88-K-0005 and the Texas Advanced Technology Program. 相似文献