全文获取类型
收费全文 | 1898篇 |
免费 | 62篇 |
国内免费 | 16篇 |
专业分类
化学 | 110篇 |
晶体学 | 2篇 |
力学 | 12篇 |
综合类 | 3篇 |
数学 | 1763篇 |
物理学 | 86篇 |
出版年
2022年 | 5篇 |
2021年 | 5篇 |
2020年 | 11篇 |
2019年 | 66篇 |
2018年 | 71篇 |
2017年 | 45篇 |
2016年 | 32篇 |
2015年 | 32篇 |
2014年 | 64篇 |
2013年 | 75篇 |
2012年 | 47篇 |
2011年 | 95篇 |
2010年 | 79篇 |
2009年 | 117篇 |
2008年 | 121篇 |
2007年 | 117篇 |
2006年 | 92篇 |
2005年 | 78篇 |
2004年 | 72篇 |
2003年 | 59篇 |
2002年 | 57篇 |
2001年 | 79篇 |
2000年 | 80篇 |
1999年 | 91篇 |
1998年 | 76篇 |
1997年 | 53篇 |
1996年 | 34篇 |
1995年 | 35篇 |
1994年 | 41篇 |
1993年 | 19篇 |
1992年 | 20篇 |
1991年 | 15篇 |
1990年 | 3篇 |
1989年 | 9篇 |
1988年 | 9篇 |
1987年 | 6篇 |
1986年 | 3篇 |
1985年 | 8篇 |
1984年 | 2篇 |
1983年 | 8篇 |
1982年 | 3篇 |
1981年 | 3篇 |
1980年 | 3篇 |
1979年 | 4篇 |
1978年 | 6篇 |
1977年 | 4篇 |
1976年 | 13篇 |
1975年 | 3篇 |
1974年 | 2篇 |
1973年 | 2篇 |
排序方式: 共有1976条查询结果,搜索用时 15 毫秒
1.
《Mathematische Nachrichten》2018,291(8-9):1177-1190
We introduce homogeneous Besov and Triebel–Lizorkin spaces with variable indexes. We show that their study reduces to the study of inhomogeneous variable exponent spaces and homogeneous constant exponent spaces. Corollaries include trace space characterizations and Sobolev embeddings. 相似文献
2.
We prove a sharp estimate for the k-modulus of smoothness, modelled upon a -Lebesgue space, of a function f in , where Ω is a domain with minimally smooth boundary and finite Lebesgue measure, , and . This sharp estimate is used to establish necessary and sufficient conditions for continuous embeddings of Sobolev-type spaces into generalized Hölder spaces defined by means of the k-modulus of smoothness. General results are illustrated with examples. In particular, we obtain a generalization of the classical Jawerth embeddings. 相似文献
3.
For a general dyadic grid, we give a Calderón–Zygmund type decomposition, which is the principle fact about the multilinear maximal function on the upper half‐spaces. Using the decomposition, we study the boundedness of . We obtain a natural extension to the multilinear setting of Muckenhoupt's weak‐type characterization. We also partially obtain characterizations of Muckenhoupt's strong‐type inequalities with one weight. Assuming the reverse Hölder's condition, we get a multilinear analogue of Sawyer's two weight theorem. Moreover, we also get Hytönen–Pérez type weighted estimates. 相似文献
4.
5.
Xuan Thinh Duong Irina Holmes Ji Li Brett D. Wick Dongyong Yang 《Journal of Functional Analysis》2019,276(4):1007-1060
In this paper we establish the characterization of the weighted BMO via two weight commutators in the settings of the Neumann Laplacian on the upper half space and the reflection Neumann Laplacian on with respect to the weights associated to and respectively. This in turn yields a weak factorization for the corresponding weighted Hardy spaces, where in particular, the weighted class associated to is strictly larger than the Muckenhoupt weighted class and contains non-doubling weights. In our study, we also make contributions to the classical Muckenhoupt–Wheeden weighted Hardy space (BMO space respectively) by showing that it can be characterized via the area function (Carleson measure respectively) involving the semigroup generated by the Laplacian on and that the duality of these weighted Hardy and BMO spaces holds for Muckenhoupt weights with while the previously known related results cover only . We also point out that this two weight commutator theorem might not be true in the setting of general operators L, and in particular we show that it is not true when L is the Dirichlet Laplacian on . 相似文献
6.
以USY分子筛为载体,采用共沉淀-浸渍法制备分子筛超强酸SO42-/Ti O2/USY,用其催化丙二酸、无水乙醇合成胡萝卜酸乙酯。考察了不同反应时间、带水剂种类、带水剂用量、醇酸比、催化剂用量、催化剂重复使用性等因素对反应酯化率的影响。结果表明:在丙二酸用量为0.1mol,醇酸摩尔比为3.1:1,催化剂用量为1.0g,反应时间为3h,带水剂环已烷用量为5m L时,酯化率达到92.13%,催化剂重复使用5次以后仍然有很高的活性。说明SO42-/Ti O2/USY对该反应具有很强且极稳定的催化活性。 相似文献
7.
It is proposed a class of statistical estimators H =(H_1,…,H_d) for the Hurst parameters H =(H_1,…,H_d) of fractional Brownian field via multi-dimensional wavelet analysis and least squares,which are asymptotically normal.These estimators can be used to detect self-similarity and long-range dependence in multi-dimensional signals,which is important in texture classification and improvement of diffusion tensor imaging(DTI) of nuclear magnetic resonance(NMR).Some fractional Brownian sheets will be simulated and the simulated data are used to validate these estimators.We find that when H_i ≥ 1/2,the estimators are accurate,and when H_i 1/2,there are some bias. 相似文献
8.
《Mathematische Nachrichten》2017,290(1):19-36
Given and a Young function η, we consider the generalized fractional maximal operator defined by where the supremum is taken over every ball B contained in . In this article, we give necessary and sufficient Dini type conditions on the functions , 42cc-9f7b-891a21e2e165/mana201500167-math-0006.png"> and η such that is bounded from the Orlicz space into the Orlicz space . We also present a version of this result for open subsets of with finite measure. Both results generalize those contained in 6 and 14 when , respectively. As a consequence, we obtain a characterization of the functions involved in the boundedness of the higher order commutators of the fractional integral operator with BMO symbols. Moreover, we give sufficient conditions that guarantee the continuity in Orlicz spaces of a large class of fractional integral operators of convolution type with less regular kernels and their commutators, which are controlled by . 相似文献
9.
《Mathematische Nachrichten》2017,290(1):37-49
We prove that Burenkov's extension operator preserves Sobolev spaces built on general Morrey spaces, including classical Morrey spaces. The analysis concerns bounded and unbounded open sets with Lipschitz boundaries in the n‐dimensional Euclidean space. 相似文献
10.
《Mathematische Nachrichten》2017,290(14-15):2388-2400
In this paper, we study the high‐dimensional Hausdorff type operators and establish their boundedness on the power weighted Hardy spaces for . As a consequence, we obtain that the Hausdorff type operator is bounded on if Φ is the Gauss function, or the Poisson function. 相似文献