全文获取类型
收费全文 | 742篇 |
免费 | 17篇 |
国内免费 | 10篇 |
专业分类
化学 | 570篇 |
晶体学 | 16篇 |
力学 | 4篇 |
数学 | 105篇 |
物理学 | 74篇 |
出版年
2023年 | 2篇 |
2022年 | 2篇 |
2021年 | 9篇 |
2020年 | 6篇 |
2019年 | 16篇 |
2018年 | 5篇 |
2017年 | 11篇 |
2016年 | 14篇 |
2015年 | 6篇 |
2014年 | 22篇 |
2013年 | 32篇 |
2012年 | 44篇 |
2011年 | 55篇 |
2010年 | 23篇 |
2009年 | 31篇 |
2008年 | 40篇 |
2007年 | 40篇 |
2006年 | 45篇 |
2005年 | 42篇 |
2004年 | 48篇 |
2003年 | 38篇 |
2002年 | 32篇 |
2001年 | 17篇 |
2000年 | 17篇 |
1999年 | 3篇 |
1998年 | 15篇 |
1997年 | 14篇 |
1996年 | 13篇 |
1995年 | 3篇 |
1994年 | 5篇 |
1993年 | 6篇 |
1992年 | 4篇 |
1991年 | 6篇 |
1990年 | 8篇 |
1989年 | 11篇 |
1988年 | 7篇 |
1987年 | 3篇 |
1986年 | 4篇 |
1985年 | 8篇 |
1984年 | 11篇 |
1983年 | 7篇 |
1982年 | 7篇 |
1981年 | 4篇 |
1980年 | 6篇 |
1979年 | 5篇 |
1978年 | 3篇 |
1977年 | 3篇 |
1975年 | 7篇 |
1974年 | 3篇 |
1939年 | 1篇 |
排序方式: 共有769条查询结果,搜索用时 15 毫秒
41.
Dr. Yohei Hattori Tatsuya Maejima Yumi Sawae Jun-ichiro Kitai Prof. Masakazu Morimoto Dr. Ryojun Toyoda Prof. Hiroshi Nishihara Prof. Satoshi Yokojima Dr. Shinichiro Nakamura Prof. Kingo Uchida 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(50):11441-11450
The cyclization reaction of diarylethenes having an azulene ring occurs only via higher excited states. Novel diarylethenes having an azulene ring with a strong donor or acceptor were synthesized and examined in these reactions. A derivative having an electron-donating 1,3-benzodithiol-2-ylidenemethyl group at the 1-position of the azulene ring showed photochromism, whereas neither a derivative having a π-conjugated electron-donating group at the 3-position of the azulene ring nor derivatives having a π-conjugated electron-withdrawing group at the 1- or 3-position of the azulene ring showed any photochromism. The photoreactivities of these compounds were explained by calculating forces and bond orders on the excited states using density functional theory (DFT) and time-dependent (TD)-DFT. 相似文献
42.
We introduce a quantum key distribution protocol using mean multi-kings’ problem. Using this protocol, a sender can share a bit sequence as a secret key with receivers. We consider a relation between information gain by an eavesdropper and disturbance contained in legitimate users’ information. In BB84 protocol, such relation is known as the so-called information disturbance theorem. We focus on a setting that the sender and two receivers try to share bit sequences and the eavesdropper tries to extract information by interacting legitimate users’ systems and an ancilla system. We derive trade-off inequalities between distinguishability of quantum states corresponding to the bit sequence for the eavesdropper and error probability of the bit sequence shared with the legitimate users. Our inequalities show that eavesdropper’s extracting information regarding the secret keys inevitably induces disturbing the states and increasing the error probability. 相似文献
43.
44.
45.
This paper proposes the use of a formal grammar for the verification of mathematical formulae for a practical mathematical
OCR system. Like a C compiler detecting syntax errors in a source file, we want to have a verification mechanism to find errors
in the output of mathematical OCR. A linear monadic context-free tree grammar (LM-CFTG) is employed as a formal framework
to define “well-formed” mathematical formulae. A cubic time parsing algorithm for LM-CFTGs is presented. For the purpose of
practical evaluation, a verification system for mathematical OCR is developed, and the effectiveness of the system is demonstrated
by using the ground-truthed mathematical document database InftyCDB-1 and a misrecognition database newly constructed for
this study. 相似文献
46.
Tae-Ho Kim Masakazu Saito Masaya Matsuoka Shinya Tsukada Kiyohisa Wada Masakazu Anpo 《Research on Chemical Intermediates》2010,36(5):453-461
It was found that the photoelectrochemical performance and photocatalytic activity of rod-type TiO2 electrodes were affected by various post-calcination treatments, for example, calcination in NH3 or under vacuum. Post-calcination treatment in NH3 at 773 K was particularly effective in increasing the photoelectrochemical performance and photocatalytic activity of rod-type
TiO2 electrodes. A unique photoelectrochemical circuit was constructed by connecting a rod-type TiO2 electrode to a Pt electrode through a silicon solar cell in which the negative bias was applied on the rod-type TiO2 electrode. It was found that the photoelectrochemical circuit can effectively oxidize ethanethiol in water into CO2. 相似文献
47.
Kenji Kashima Masakazu Kato Jun-ichi Imura Kazuyuki Aihara 《The European physical journal. Special topics》2014,223(12):2493-2501
We propose a novel framework for probabilistic evaluation of interconnectable capacity for wind power generation. This is based on mathematical modeling of load frequency control systems, which captures their nonlinear (saturation and rate limiting) dynamical characteristics, and stochastic uncertainty of wind power output deviation. The method called stochastic linearization is used to analyze resulting power quality. The effectiveness of the proposed method is examined by numerical simulation. 相似文献
48.
Masakazu Teragaito 《Proceedings of the American Mathematical Society》2002,130(9):2803-2808
For a hyperbolic knot in , a toroidal surgery is Dehn surgery which yields a -manifold containing an incompressible torus. It is known that a toroidal surgery on is an integer or a half-integer. In this paper, we prove that all integers occur among the toroidal slopes of hyperbolic knots with bridge index at most three and tunnel number one.
49.
Ohkita M Kawano M Suzuki T Tsuji T 《Chemical communications (Cambridge, England)》2002,(24):3054-3055
The crystallization of 2,4,6-triethynyl-1,3,5-triazine (2) leads to a pi-stacked layered structure of a C(sp)-H...N hydrogen-bonded unique hexagonal network structure, which may be regarded as a supramolecular analogue of a hitherto unknown graphyne network: in-plane intermolecular interactions are short and linear H...N contacts (2.31 and 2.34 A) and the interlayer separation is 3.23 A. 相似文献
50.
Fumihiko Yamaguchi Masakazu Nakanishi 《International Journal of Theoretical Physics》1996,35(10):2107-2116
Linear logic, introduced by Girardet al., has a great power of expression, but no method for induction. This paper proposes a method of induction using knowledge
represented by linear logical formulas. In linear logic, the number of propositions is controlled by logical operators. When
a background theory and a hypothesis prove an example, the number of propositions on each side must be equivalent. 相似文献