全文获取类型
收费全文 | 2327篇 |
免费 | 79篇 |
国内免费 | 8篇 |
专业分类
化学 | 1460篇 |
晶体学 | 24篇 |
力学 | 57篇 |
数学 | 332篇 |
物理学 | 541篇 |
出版年
2023年 | 39篇 |
2022年 | 61篇 |
2021年 | 89篇 |
2020年 | 63篇 |
2019年 | 64篇 |
2018年 | 78篇 |
2017年 | 48篇 |
2016年 | 90篇 |
2015年 | 87篇 |
2014年 | 91篇 |
2013年 | 158篇 |
2012年 | 141篇 |
2011年 | 184篇 |
2010年 | 82篇 |
2009年 | 93篇 |
2008年 | 133篇 |
2007年 | 110篇 |
2006年 | 93篇 |
2005年 | 82篇 |
2004年 | 69篇 |
2003年 | 42篇 |
2002年 | 47篇 |
2001年 | 27篇 |
2000年 | 38篇 |
1999年 | 22篇 |
1998年 | 16篇 |
1997年 | 22篇 |
1996年 | 23篇 |
1995年 | 15篇 |
1994年 | 16篇 |
1993年 | 27篇 |
1992年 | 9篇 |
1991年 | 17篇 |
1990年 | 14篇 |
1989年 | 10篇 |
1988年 | 13篇 |
1987年 | 15篇 |
1986年 | 10篇 |
1985年 | 12篇 |
1984年 | 16篇 |
1983年 | 10篇 |
1982年 | 10篇 |
1981年 | 10篇 |
1980年 | 8篇 |
1979年 | 11篇 |
1978年 | 13篇 |
1977年 | 9篇 |
1976年 | 8篇 |
1974年 | 6篇 |
1973年 | 7篇 |
排序方式: 共有2414条查询结果,搜索用时 15 毫秒
1.
Corinne Rondeau-Mouro Mireille Cambert Laurent Blondel Yves Diascorn Léo Mbaya Nor Nadiah Binti Ahmad Nazari Sarah Helary Tiphaine Lucas 《Magnetic resonance in chemistry : MRC》2022,60(7):678-691
A temperature control unit was implemented to vary the temperature of samples studied on a commercial Mobile Universal Surface Explorer nuclear magnetic resonance (MOUSE-NMR) apparatus. The device was miniaturized to fit the maximum MOUSE sampling depth (25 mm). It was constituted by a sample holder sandwiched between two heat exchangers placed below and above the sample. Air was chosen as the fluid to control the temperature at the bottom of the sample, at the interface between the NMR probe and the sample holder, in order to gain space. The upper surface of the sample was regulated by the circulation of water inside a second heat exchanger placed above the sample holder. The feasibility of using such a device was demonstrated first on pure water and then on several samples of bread dough with different water contents. For this, T1 relaxation times were measured at various temperatures and depths and were then compared with those acquired with a conventional compact closed-magnet spectrometer. Discussion of results was based on biochemical transformations in bread dough (starch gelatinization and gluten heat denaturation). It was demonstrated that, within a certain water level range, and because of the low magnetic field strength of the MOUSE, a linear relationship could be established between T1 relaxation times and the local temperature in the dough sample. 相似文献
2.
3.
4.
5.
6.
Condeixa Lucas Dias Silva Pierry Moah Diego Farias Brenda Leiras Adriana 《Central European Journal of Operations Research》2022,30(3):921-940
Central European Journal of Operations Research - Societal awareness and legislation changes concerning sustainability have affected how organizations generate value for stakeholders, as well as... 相似文献
7.
Affine Arithmetic: Concepts and Applications 总被引:2,自引:0,他引:2
Affine arithmetic is a model for self-validated numerical computation that keeps track of first-order correlations between computed and input quantities. We explain the main concepts in affine arithmetic and how it handles the dependency problem in standard interval arithmetic. We also describe some of its applications. 相似文献
8.
We present an O(min(Kn,n2)) algorithm to solve the maximum integral multiflow and minimum multicut problems in rooted trees, where K is the number of commodities and n is the number of vertices. These problems are NP-hard in undirected trees but polynomial in directed trees. In the algorithm we propose, we first use a greedy procedure to build the multiflow then we use duality properties to obtain the multicut and prove the optimality. 相似文献
9.
The gedanken experiment of the clock paradox is solved exactly using the general relativistic equations for a static homogeneous gravitational
field. We demonstrate that the general and special relativistic clock paradox solutions are identical and in particular that
they are identical for finite acceleration. Practical expressions are obtained for proper time and coordinate time by using the destination distance as
the key observable parameter. This solution provides a formal demonstration of the identity between the special and general
relativistic clock paradox with finite acceleration and where proper time is assumed to be the same in both formalisms. By
solving the equations of motion for a freely falling clock in a static homogeneous field elapsed times are calculated for
realistic journeys to the stars.
1 Both authors contributed equally to this paper. 相似文献
10.
We analyze the well-posedness of the initial value problem for the dissipative quasi-geostrophic equations in the subcritical
case. Mild solutions are obtained in several spaces with the right homogeneity to allow the existence of self-similar solutions.
While the only small self-similar solution in the strong
Lp{\cal L}^{p}
space is the null solution, infinitely many self-similar solutions do exist in weak-
Lp{\cal L}^{p}
spaces and in a recently introduced [7] space of tempered distributions. The asymptotic stability of solutions is obtained
in both spaces, and as a consequence, a criterion of self-similarity persistence at large times is obtained. 相似文献