全文获取类型
收费全文 | 13535篇 |
免费 | 910篇 |
国内免费 | 1071篇 |
学科分类
数理化 | 15516篇 |
出版年
2023年 | 137篇 |
2022年 | 135篇 |
2021年 | 196篇 |
2020年 | 284篇 |
2019年 | 362篇 |
2018年 | 323篇 |
2017年 | 377篇 |
2016年 | 338篇 |
2015年 | 334篇 |
2014年 | 575篇 |
2013年 | 1008篇 |
2012年 | 480篇 |
2011年 | 693篇 |
2010年 | 574篇 |
2009年 | 803篇 |
2008年 | 901篇 |
2007年 | 903篇 |
2006年 | 838篇 |
2005年 | 760篇 |
2004年 | 623篇 |
2003年 | 659篇 |
2002年 | 571篇 |
2001年 | 447篇 |
2000年 | 401篇 |
1999年 | 380篇 |
1998年 | 380篇 |
1997年 | 330篇 |
1996年 | 223篇 |
1995年 | 156篇 |
1994年 | 139篇 |
1993年 | 116篇 |
1992年 | 108篇 |
1991年 | 101篇 |
1990年 | 53篇 |
1989年 | 65篇 |
1988年 | 61篇 |
1987年 | 47篇 |
1986年 | 55篇 |
1985年 | 72篇 |
1984年 | 63篇 |
1983年 | 35篇 |
1982年 | 53篇 |
1981年 | 61篇 |
1980年 | 60篇 |
1979年 | 58篇 |
1978年 | 42篇 |
1977年 | 38篇 |
1976年 | 27篇 |
1975年 | 14篇 |
1974年 | 15篇 |
排序方式: 共有10000条查询结果,搜索用时 241 毫秒
1.
2.
《Indagationes Mathematicae》2021,32(1):55-85
We show that the differential structure of the orbit space of a proper action of a Lie group on a smooth manifold is weakly reflexive. This implies that the orbit space is a differentiable space in the sense of Smith, which ensures that the orbit space has an exterior algebra of differential forms, that satisfies Smith’s version of de Rham’s theorem. Because the orbit space is a locally closed subcartesian space, it has vector fields and their flows. 相似文献
3.
A finite support product of clones of Jensen's minimal singleton forcing is used to define a model in which any non-empty analytically definable set of reals contains an analytically definable real (the full basis theorem), but there is no analytically definable wellordering of the reals. 相似文献
4.
Marcus Carlsson 《Expositiones Mathematicae》2021,39(1):149-157
von Neumann’s inequality in matrix theory refers to the fact that the Frobenius scalar product of two matrices is less than or equal to the scalar product of the respective singular values. Moreover, equality can only happen if the two matrices share a joint set of singular vectors, and this latter part is hard to find in the literature. We extend these facts to the separable Hilbert space setting, and provide a self-contained proof of the “latter part”. 相似文献
5.
6.
Liang Zhao 《Journal of Differential Equations》2019,266(9):5615-5624
In this paper, let be n-dimensional noncompact metric measure space which satisfies Poincaré inequality with some Ricci curvature condition. We obtain a Liouville theorem for positive weak solutions to weighted p-Lichnerowicz equation where are real constants. 相似文献
7.
8.
《Comptes Rendus Physique》2015,16(2):193-203
The field of multiferroics has experienced a rapid progress resulting in the discovery of many new physical phenomena. BiFeO3 (BFO) compound, which is one of the few room-temperature single-phase multiferroics, has contributed subsequently to this progress. As a result, significant review articles have been devoted specifically to this famous system. This chapter is dedicated to the strain effects on the structure stability and property changes of BFO thin films. It is a short and non-exhaustive topical overview that may be seen as an invitation for interested readers to go beyond. There is a very active and prolific research in this field and we apologize to the authors whose relevant work is not cited here. After a short introduction, we will thus review the effect of strain on BFO films by describing the consequences on the structure and the phase transitions as well as on polar, magnetic and magnetoelectric properties. 相似文献
9.
In this paper, we propose a sufficient and necessary condition for the boundedness of all the solutions for the equation with the critical situation that on g and p, where , is periodic and is bounded. 相似文献
10.
Design and development of a two‐dimensional system based on hydrophilic and reversed‐phase liquid chromatography with on‐line sample treatment for the simultaneous separation of excreted xenobiotics and endogenous metabolites in urine 下载免费PDF全文
Diego García‐Gómez Encarnación Rodríguez‐Gonzalo Rita Carabias‐Martínez 《Biomedical chromatography : BMC》2015,29(8):1190-1196
In the present work we describe a two‐dimensional liquid chromatographic system (2D‐LC) with detection by mass spectrometry (MS) for the simultaneous separation of endogenous metabolites of clinical interest and excreted xenobiotics deriving from exposure to toxic compounds. The 2D‐LC system involves two orthogonal chromatographic modes, hydrophilic interaction liquid chromatography (HILIC) to separate polar endogenous metabolites and reversed‐phase (RP) chromatography to separate excreted xenobiotics of low and intermediate polarity. Additionally, the present proposal has the novelty of incorporating an on‐line sample treatment based on the use of restricted access materials (RAMs), which permits the direct injection of urine samples into the system. The work is focused on the instrumental coupling, studying all possible options and attempting to circumvent the problems of solvent incompatibility between the RAM device and the two chromatographic columns, HILIC and RP. The instrumental configuration developed, RAM‐HILIC‐RPLC‐MS/MS, allows the simultaneous assessment of urinary metabolites of clinical interest and excreted compounds derived from exposure to toxic agents with minimal sample manipulation. Thus, it may be of interest in areas such as occupational and environmental toxicology in order to explore the possible relationship between the two types of compounds. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献