全文获取类型
收费全文 | 6148篇 |
免费 | 110篇 |
国内免费 | 40篇 |
专业分类
化学 | 4315篇 |
晶体学 | 40篇 |
力学 | 124篇 |
数学 | 992篇 |
物理学 | 827篇 |
出版年
2022年 | 33篇 |
2021年 | 49篇 |
2020年 | 75篇 |
2019年 | 61篇 |
2018年 | 38篇 |
2017年 | 35篇 |
2016年 | 90篇 |
2015年 | 87篇 |
2014年 | 99篇 |
2013年 | 258篇 |
2012年 | 266篇 |
2011年 | 345篇 |
2010年 | 152篇 |
2009年 | 133篇 |
2008年 | 287篇 |
2007年 | 364篇 |
2006年 | 342篇 |
2005年 | 336篇 |
2004年 | 253篇 |
2003年 | 252篇 |
2002年 | 248篇 |
2001年 | 84篇 |
2000年 | 89篇 |
1999年 | 79篇 |
1998年 | 90篇 |
1997年 | 64篇 |
1996年 | 137篇 |
1995年 | 97篇 |
1994年 | 79篇 |
1993年 | 99篇 |
1992年 | 84篇 |
1991年 | 55篇 |
1990年 | 79篇 |
1989年 | 69篇 |
1988年 | 72篇 |
1987年 | 65篇 |
1986年 | 61篇 |
1985年 | 92篇 |
1984年 | 103篇 |
1983年 | 57篇 |
1982年 | 85篇 |
1981年 | 81篇 |
1980年 | 67篇 |
1979年 | 75篇 |
1978年 | 78篇 |
1977年 | 66篇 |
1976年 | 64篇 |
1975年 | 73篇 |
1974年 | 68篇 |
1973年 | 47篇 |
排序方式: 共有6298条查询结果,搜索用时 46 毫秒
1.
Michael K. Kinyon Kenneth Kunen J. D. Phillips 《Proceedings of the American Mathematical Society》2002,130(3):619-624
An A-loop is a loop in which every inner mapping is an automorphism. A problem which had been open since 1956 is settled by showing that every diassociative A-loop is Moufang.
2.
Rachel L. McSwain Alison R. Markowitz Kenneth R. Shull 《Journal of Polymer Science.Polymer Physics》2004,42(20):3809-3821
To develop a greater understanding of interfacial interactions between a semicrystalline polymer and a glassy polymer, adhesion tests were performed on very thin layers of poly(ethylene oxide) (PEO) sandwiched between two layers of poly(tetramethyl bisphenol A polycarbonate) (TMPC). The tests were designed to provide intimate contact between the surfaces while they were heated above the melting point of the PEO and cooled back to room temperature. A contact mechanics approach, based on the Johnson, Kendall, and Roberts theory, was used to determine values of the energy release rate describing the energetic driving force for crack propagation within the interfacial region. The ability to measure crack propagation at large values of the energy release rate was limited by rupture of the silicone elastomer that was used to provide a sufficiently compliant matrix for the adhesion experiment. By cycling the tensile stress at relatively low loading levels, we were able to measure fatigue crack propagation at values of the energy release rate that did not result in failure of the elastomer. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 3809–3821, 2004 相似文献
3.
Kenneth Weber Vilmar Trevisan Luiz Felipe Martins 《Journal of Algorithms in Cognition, Informatics and Logic》2005,54(2):152-167
This paper describes the first algorithm to compute the greatest common divisor (GCD) of two n-bit integers using a modular representation for intermediate values U, V and also for the result. It is based on a reduction step, similar to one used in the accelerated algorithm [T. Jebelean, A generalization of the binary GCD algorithm, in: ISSAC '93: International Symposium on Symbolic and Algebraic Computation, Kiev, Ukraine, 1993, pp. 111–116; K. Weber, The accelerated integer GCD algorithm, ACM Trans. Math. Softw. 21 (1995) 111–122] when U and V are close to the same size, that replaces U by (U−bV)/p, where p is one of the prime moduli and b is the unique integer in the interval (−p/2,p/2) such that . When the algorithm is executed on a bit common CRCW PRAM with O(nlognlogloglogn) processors, it takes O(n) time in the worst case. A heuristic model of the average case yields O(n/logn) time on the same number of processors. 相似文献
4.
B. M. Azizur Rahman A. K. M. Saiful Kabir Muttukrishnan Rajarajan Kenneth T. V. Grattan 《Optical and Quantum Electronics》2005,37(1-3):171-183
Modal solutions of planar photonic crystal waveguides with rectangular air-holes are presented by using a rigorous full-vectorial finite element-based approach. The effective indices, mode field profiles, spot-sizes, power confinements, modal hybridness, beat lengths and group velocity dispersions are shown for the fundamental and higher order modes of the quasi-TE and TM polarizations. 相似文献
5.
A band-dominant function on the Euclidean sphere embedded in R q+1 is the restriction to this sphere of an entire function of q+1 complex variables having a finite exponential type in each of its variables. We develop a method to represent such a function using finitely many bits, using the values of the function at scattered sites on the sphere. The number of bits required in our representation is asymptotically the same as the metric entropy of the class of such functions with respect to any of the L p norms on the sphere. 相似文献
6.
7.
Thomas M. F. Case G. S. Bland J. Herring A. D. F. Stirling W. G. Tixier S. Boni P. Ward R. C. C. Wells M. R. Langridge S. 《Hyperfine Interactions》2002,141(1-4):471-476
Hyperfine Interactions - Multilayers of Ce/Fe and U/Fe were fabricated by sputtering and studied by X-ray diffraction and reflectivity, Mössbauer spectroscopy and polarised neutron... 相似文献
8.
The Meyerhoff Program is an intensive, multicomponent program focused on enhancing the success of talented African-American students in science and engineering at a predominantly white, medium-sized university. The program components, taken together, address the four primary factors emphasized in the research literature as limiting minority student performance and persistence in science: knowledge and skills, motivation and support, monitoring and advising, and academic and social integration. Outcome analyses indicated that the first three cohorts of Meyerhoff students (total N=69) achieved an overall GPA (mean=3.5) significantly greater than that of an African-American historical comparison sample (mean=2.8) of comparably talented science students at the university. This difference was even greater for first year science GPA (means of 3.4 and 2.4, respectively), and in specific science and mathematics courses. Observational and questionnaire data indicated that the Meyerhoff program study groups, peerbased community, financial scholarships, summer bridge program and staff appear to be especially important contributors to student success. Implications of the findings for enhancing the success of African-American and other underrepresented populations in science are discussed. 相似文献
9.
Applied Biochemistry and Biotechnology - In summary, it appears that the microbial reduction process is clearly not competitive with conventional SO2-reduction techniques when glucose (DE95 corn... 相似文献
10.