全文获取类型
收费全文 | 2459篇 |
免费 | 98篇 |
国内免费 | 18篇 |
专业分类
化学 | 1559篇 |
晶体学 | 30篇 |
力学 | 41篇 |
数学 | 367篇 |
物理学 | 578篇 |
出版年
2023年 | 18篇 |
2022年 | 15篇 |
2021年 | 22篇 |
2020年 | 25篇 |
2019年 | 36篇 |
2018年 | 39篇 |
2017年 | 19篇 |
2016年 | 62篇 |
2015年 | 48篇 |
2014年 | 57篇 |
2013年 | 109篇 |
2012年 | 121篇 |
2011年 | 160篇 |
2010年 | 86篇 |
2009年 | 102篇 |
2008年 | 155篇 |
2007年 | 156篇 |
2006年 | 128篇 |
2005年 | 133篇 |
2004年 | 103篇 |
2003年 | 90篇 |
2002年 | 65篇 |
2001年 | 47篇 |
2000年 | 56篇 |
1999年 | 40篇 |
1998年 | 24篇 |
1997年 | 23篇 |
1996年 | 40篇 |
1994年 | 22篇 |
1993年 | 30篇 |
1992年 | 30篇 |
1991年 | 24篇 |
1990年 | 28篇 |
1989年 | 35篇 |
1988年 | 33篇 |
1987年 | 32篇 |
1986年 | 31篇 |
1985年 | 37篇 |
1984年 | 34篇 |
1983年 | 18篇 |
1982年 | 20篇 |
1981年 | 30篇 |
1980年 | 20篇 |
1979年 | 13篇 |
1978年 | 26篇 |
1977年 | 12篇 |
1976年 | 18篇 |
1975年 | 20篇 |
1974年 | 11篇 |
1973年 | 19篇 |
排序方式: 共有2575条查询结果,搜索用时 781 毫秒
1.
2.
V. Bena Jothy T. Vijayakumar D. Sajan V. S. Jayakumar I. Hubert Joe 《Laser Physics》2006,16(8):1242-1252
Single crystals of sarcosinium oxalate monohydrate (SOM) are grown by the slow-evaporation technique at ambient temperature, and vibrational spectroscopic analysis is carried out using NIR-FT Raman, FT-IR, and SERS spectra. The normal mode frequencies and corresponding vibrational analysis of SOM are examined theoretically using the Gaussian’98 set of quantum chemical codes. The two bands present in the SOM ν C=O region, clearly observed in the Raman spectrum, are assigned to “free” and “bonded” carbonyl groups with the hydrogen atom. Vibrational analysis indicates the presence of C-H—O hydrogen bonding interaction producing a blueshift of the C-H stretching frequency. 相似文献
3.
Yasuyuki Agari Kiyofumi Sakai Yosikazu Kano Ryoki Nomura 《Journal of Polymer Science.Polymer Physics》2007,45(21):2972-2981
We prepared biodegradable poly(ethylene oxide) (PEO)/poly(L ‐lactic acid) (PLLA) graded blends by the dissolution–diffusion process, and discussed the biodegradability and tensile strength of the graded blends by comparing isotropic blend and PLLA only. All the graded blends were degraded more largely than the PLLA only and isotropic blend (PEO: 37.5 wt %), which had the same content as the total content of those graded blends. The graded blend having most excellent wide compositional gradient was degraded most largely with the enzyme. Thus, graded structure of the blends promoted their biodegradabilities large. It was considered that the dissolution of PEO with water increased the surface area attacked by the enzyme, while PEO caught PLLA oligomers to promote the biodegradation of PLLA. Then, the biodegradabilities of the graded blends were suppressed by the increasing crystallinity of PLLA. Furthermore, the strengths of all the graded blends were larger than those of the isotropic blend. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 2972–2981, 2007 相似文献
4.
Ionel Rosenthal Joe Z. Sostaric Peter Riesz 《Research on Chemical Intermediates》2004,30(7-8):685-701
Sonochemistry and photochemistry are initiated by high-energy transient species, which may be prone to mutual interaction. Electronic excitation of solutes by energy transfer from high energy species generated in collapsing bubbles is already supported by experimental evidence. The rates of photochemical reactions can be affected by ultrasound-induced mixing of liquids caused by microstreaming near pulsating cavitation bubbles and shockwaves due to bubble collapse. This may not only improve light absorption but also modify the pathway of reaction by increasing the contact between reagents. Finally, one may speculate about a potentially new chemistry of photoexcited solutes under the extreme conditions inside cavitation microreactors. This work reviews research on the excitation of solutes by sonoluminescence, the combined effects of ultrasound and light on liquid systems and the effect of ultrasound on photocatalytic reactions. 相似文献
5.
6.
7.
Let Cld
AW
(X) be the hyperspace of nonempty closed subsets of a normed linear space X with the Attouch–Wets topology. It is shown that the space Cld
AW
(X) and its various subspaces are AR's. Moreover, if X is an infinite-dimensional Banach space with weight w(X) then Cld
AW
(X) is homeomorphic to a Hilbert space with weight 2
w(X). 相似文献
8.
9.
Joe Warren Scott Schaefer Anil N. Hirani Mathieu Desbrun 《Advances in Computational Mathematics》2007,27(3):319-338
In this paper we provide an extension of barycentric coordinates from simplices to arbitrary convex sets. Barycentric coordinates
over convex 2D polygons have found numerous applications in various fields as they allow smooth interpolation of data located
on vertices. However, no explicit formulation valid for arbitrary convex polytopes has been proposed to extend this interpolation
in higher dimensions. Moreover, there has been no attempt to extend these functions into the continuous domain, where barycentric
coordinates are related to Green’s functions and construct functions that satisfy a boundary value problem. First, we review
the properties and construction of barycentric coordinates in the discrete domain for convex polytopes. Next, we show how
these concepts extend into the continuous domain to yield barycentric coordinates for continuous functions. We then provide
a proof that our functions satisfy all the desirable properties of barycentric coordinates in arbitrary dimensions. Finally,
we provide an example of constructing such barycentric functions over regions bounded by parametric curves and show how they
can be used to perform freeform deformations.
相似文献
10.
Selective oxidation of an AlInAs layer was investigated for enhancement of magneto-optic effect in an optical isolator. Twelve times nonreciprocal phase shift enhancement was estimated from a measured AlInAs-oxide refractive index. 相似文献