全文获取类型
收费全文 | 2981篇 |
免费 | 72篇 |
国内免费 | 18篇 |
专业分类
化学 | 1514篇 |
晶体学 | 47篇 |
力学 | 97篇 |
数学 | 915篇 |
物理学 | 498篇 |
出版年
2023年 | 19篇 |
2022年 | 28篇 |
2021年 | 58篇 |
2020年 | 53篇 |
2019年 | 74篇 |
2018年 | 110篇 |
2017年 | 112篇 |
2016年 | 124篇 |
2015年 | 100篇 |
2014年 | 138篇 |
2013年 | 383篇 |
2012年 | 174篇 |
2011年 | 186篇 |
2010年 | 194篇 |
2009年 | 139篇 |
2008年 | 180篇 |
2007年 | 177篇 |
2006年 | 121篇 |
2005年 | 96篇 |
2004年 | 74篇 |
2003年 | 61篇 |
2002年 | 57篇 |
2001年 | 29篇 |
2000年 | 34篇 |
1999年 | 27篇 |
1998年 | 21篇 |
1997年 | 20篇 |
1996年 | 21篇 |
1995年 | 13篇 |
1993年 | 9篇 |
1992年 | 6篇 |
1989年 | 9篇 |
1988年 | 6篇 |
1987年 | 14篇 |
1986年 | 12篇 |
1985年 | 16篇 |
1984年 | 15篇 |
1983年 | 10篇 |
1982年 | 13篇 |
1981年 | 20篇 |
1980年 | 7篇 |
1979年 | 13篇 |
1978年 | 7篇 |
1977年 | 8篇 |
1976年 | 15篇 |
1975年 | 6篇 |
1974年 | 11篇 |
1973年 | 9篇 |
1972年 | 6篇 |
1968年 | 11篇 |
排序方式: 共有3071条查询结果,搜索用时 31 毫秒
1.
Journal of Theoretical Probability - A definition of d-dimensional n-Meixner random vectors is given first. This definition involves the commutators of their semi-quantum operators. After that we... 相似文献
2.
Samide Adriana Tutunaru Bogdan Merişanu Claudia Cioateră Nicoleta 《Journal of Thermal Analysis and Calorimetry》2020,142(5):1825-1834
Journal of Thermal Analysis and Calorimetry - To prepare a commercial product with economic and technical relevance, polyvinyl acetate (PVAc) was synthesized, under our laboratory conditions,... 相似文献
3.
4.
Quantitative determination of omega-6 and omega-3 polyunsaturated fatty acids in human plasma and urine with high accuracy and precision provides significant information to monitor the underlying etiology of several diseases. In this regard, liquid chromatography-mass spectrometry is a good choice owing to its great selectivity and sensitivity. Additionally, the hybrid quadrupole–time of flight–mass spectrometer systems provides easy identification of target compounds with superior mass measurements. In this study, an analytical method has been developed for simple, accurate and simultaneous determination of linoleic acid, arachidonic acid, docosahexaenoic acid and eicosapentaenoic acid in a short chromatographic analysis period. The developed method is suitable for the quantitative detection of these four compounds with detection limits ranging between 1.1–3.0 ng ml−1 and its applicability was assessed in human urine and plasma samples. As a result, acceptable accuracy (between 83 and 111%) and good precision (<6%) were obtained for target compounds using matrix matching calibration strategy. 相似文献
5.
6.
Altıntas Yemliha Öztürk Esra Aksöz Sezen Keşlioğlu Kâzım Maraşlı Necmettin 《Journal of Thermal Analysis and Calorimetry》2015,122(1):65-72
Journal of Thermal Analysis and Calorimetry - The equilibrated grain boundary groove shapes for solid Bi (Bi–2.87 at.%Ag) in equilibrium with Bi–Ag eutectic liquid have been... 相似文献
7.
We consider the problem of estimating a large rank-one tensor u ⊗k ∈ (ℝn)⊗k , k ≥ 3 , in Gaussian noise. Earlier work characterized a critical signal-to-noise ratio λ Bayes = O(1) above which an ideal estimator achieves strictly positive correlation with the unknown vector of interest. Remarkably, no polynomial-time algorithm is known that achieved this goal unless λ ≥ Cn(k − 2)/4 , and even powerful semidefinite programming relaxations appear to fail for 1 ≪ λ ≪ n(k − 2)/4 . In order to elucidate this behavior, we consider the maximum likelihood estimator, which requires maximizing a degree-k homogeneous polynomial over the unit sphere in n dimensions. We compute the expected number of critical points and local maxima of this objective function and show that it is exponential in the dimensions n , and give exact formulas for the exponential growth rate. We show that (for λ larger than a constant) critical points are either very close to the unknown vector u or are confined in a band of width Θ(λ−1/(k − 1)) around the maximum circle that is orthogonal to u . For local maxima, this band shrinks to be of size Θ(λ−1/(k − 2)) . These “uninformative” local maxima are likely to cause the failure of optimization algorithms. © 2019 Wiley Periodicals, Inc. 相似文献
8.
9.
10.