全文获取类型
收费全文 | 2714篇 |
免费 | 94篇 |
国内免费 | 9篇 |
专业分类
化学 | 1933篇 |
晶体学 | 31篇 |
力学 | 30篇 |
数学 | 178篇 |
物理学 | 645篇 |
出版年
2023年 | 16篇 |
2022年 | 31篇 |
2021年 | 35篇 |
2020年 | 25篇 |
2019年 | 40篇 |
2018年 | 31篇 |
2017年 | 20篇 |
2016年 | 49篇 |
2015年 | 50篇 |
2014年 | 68篇 |
2013年 | 119篇 |
2012年 | 141篇 |
2011年 | 176篇 |
2010年 | 94篇 |
2009年 | 93篇 |
2008年 | 156篇 |
2007年 | 167篇 |
2006年 | 143篇 |
2005年 | 156篇 |
2004年 | 131篇 |
2003年 | 122篇 |
2002年 | 95篇 |
2001年 | 48篇 |
2000年 | 55篇 |
1999年 | 36篇 |
1998年 | 25篇 |
1997年 | 32篇 |
1996年 | 42篇 |
1995年 | 19篇 |
1994年 | 29篇 |
1993年 | 26篇 |
1992年 | 35篇 |
1991年 | 22篇 |
1990年 | 28篇 |
1989年 | 42篇 |
1988年 | 31篇 |
1987年 | 25篇 |
1986年 | 30篇 |
1985年 | 42篇 |
1984年 | 40篇 |
1983年 | 21篇 |
1982年 | 20篇 |
1981年 | 30篇 |
1980年 | 25篇 |
1979年 | 18篇 |
1978年 | 27篇 |
1977年 | 12篇 |
1976年 | 15篇 |
1975年 | 18篇 |
1973年 | 19篇 |
排序方式: 共有2817条查询结果,搜索用时 31 毫秒
1.
2.
Inside Cover: Photoinduced Formation of an Azobenzene‐Based CD‐Active Supramolecular Cyclic Dimer (Chem. Eur. J. 18/2015)
下载免费PDF全文
![点击此处可从《Chemistry (Weinheim an der Bergstrasse, Germany)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
3.
4.
Masashi Ohkawa Yuki Shirai Takeshi Goto Seishi Sekine Takashi Sato 《Fiber and Integrated Optics》2002,21(2):105-113
In this paper, a silicon-based integrated optic pressure sensor using an intermodal interference between the fundamental TM-like and TE-like modes is described. The sensor consists of a micromachined rectangular diaphragm and a straight polystyrene optical waveguide passing over the diaphragm. Its sensitivity is theoretically known to be strongly dependent on the position of the waveguide over the diaphragm. To experimentally investigate such dependence, we fabricated a sensor with a 1.2 mm ×10 mm ×20 μm diaphragm, over which waveguides were placed at 50 μm intervals. The measured phase sensitivity was 98 mrad/kPa for the waveguide nearest to the diaphragm edge. The measurement was also carried out for the other waveguides. As theoretically expected, the largest sensitivity was obtained for the waveguide nearest to the edge. 相似文献
5.
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
6.
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
7.
Squier (1987) showed that if a monoid is defined by a finite complete rewriting system, then it satisfies the homological
finiteness condition FP3, and using this fact he gave monoids (groups) which have solvable word problems but cannot be presented by finite complete
systems. In the present paper we show that a monoid cannot have a finite complete presentation if it contains certain special
elements. This observation enables us to construct monoids without finite complete presentation in a direct and elementary
way. We give a finitely presented monoid which has (1) a word problem solvable in linear time and (2) linear growth but (3)
no finite complete presentation. We also give a finitely presented monoid which has (1) a word problem solvable in linear
time, (2) finite derivation type in the sense of Squier and (3) the property FP∞, but (4) no finite complete presentation. 相似文献
8.
Linear and nonlinear optical properties of racemic (±)2-(α-methylbenzylamino)-5-nitropyridine ((±)MBANP) single crystals have been comprehensively investigated and compared with those of the enantiomorph (–)2-(α-methylbenzylamino)-5-nitropyridine ((–)MBANP) crystals. (±)MBANP crystal exhibits very high chemical and physical stability, but relatively small nonlinear optical coefficients (d31 = 6.8 pm/V, d32 = 4.7 pm/V, d33 = 0.84 pm/V). A comparison between the nonlinear optical coefficients of (±)MBANP and (–)MBANP demonstrates the validity of the oriented-gas model in molecular crystals that neglects all the contributions from intermolecular interaction. 相似文献
9.
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