全文获取类型
收费全文 | 308篇 |
免费 | 4篇 |
专业分类
化学 | 211篇 |
晶体学 | 5篇 |
力学 | 4篇 |
数学 | 17篇 |
物理学 | 75篇 |
出版年
2022年 | 2篇 |
2021年 | 4篇 |
2020年 | 2篇 |
2019年 | 4篇 |
2018年 | 3篇 |
2017年 | 2篇 |
2016年 | 2篇 |
2015年 | 3篇 |
2014年 | 4篇 |
2013年 | 16篇 |
2012年 | 15篇 |
2011年 | 16篇 |
2010年 | 11篇 |
2009年 | 10篇 |
2008年 | 17篇 |
2007年 | 19篇 |
2006年 | 23篇 |
2005年 | 17篇 |
2004年 | 20篇 |
2003年 | 18篇 |
2002年 | 7篇 |
2001年 | 8篇 |
2000年 | 5篇 |
1999年 | 4篇 |
1996年 | 4篇 |
1995年 | 4篇 |
1994年 | 6篇 |
1993年 | 2篇 |
1992年 | 2篇 |
1991年 | 3篇 |
1990年 | 5篇 |
1989年 | 4篇 |
1987年 | 5篇 |
1986年 | 5篇 |
1985年 | 3篇 |
1984年 | 6篇 |
1983年 | 1篇 |
1982年 | 2篇 |
1981年 | 3篇 |
1980年 | 4篇 |
1979年 | 5篇 |
1978年 | 2篇 |
1977年 | 2篇 |
1976年 | 2篇 |
1975年 | 2篇 |
1973年 | 2篇 |
1971年 | 1篇 |
1967年 | 1篇 |
1966年 | 1篇 |
1962年 | 1篇 |
排序方式: 共有312条查询结果,搜索用时 0 毫秒
91.
Analysis of Non-normal Operators via Aluthge Transformation 总被引:1,自引:0,他引:1
Let T be a bounded linear operator on a complex Hilbert space
. In this paper, we show that T has Bishops property () if and only if its Aluthge transformation
has property (). As applications, we can obtain the following results. Every w-hyponormal operator has property (). Quasi-similar w-hyponormal operators have equal spectra and equal essential spectra. Moreover, in the last section, we consider Chs problem that whether the semi-hyponormality of T implies the spectral mapping theorem Re(T) = (Re T) or not. 相似文献
92.
Nishida H Miyazaki Y Mukaihira T Saitoh F Fukui M Harada K Itoh M Muraoka A Matsusue T Okamoto A Hosaka Y Matsumoto M Ohnishi S Mochizuki H 《Chemical & pharmaceutical bulletin》2002,50(9):1187-1194
Intravascular clot formation is an important event in a number of cardiovascular diseases. The prevention of blood coagulation has become a major target for new therapeutic agents. Factor Xa (FXa) is a trypsin-like serine protease that plays a key role in the blood coagulation cascade and represents an attractive target for anticoagulant drug development. We have investigated substituents in the central part of a lead compound (3: M55113), and discovered that compound M55551 (34: (R)-4-[(6-Chloro-2-naphthalenyl)sulfonyl]-6-oxo-1-[[1-(4-pyridinyl)-4-piperidinyl]methyl]-2-piperazinecarboxylic acid) is a potent inhibitor of FXa (IC(50)=0.006 microM), with high selectivity for FXa over trypsin and thrombin. The activity of this compound is ten times more powerful than the lead compound. 相似文献
93.
94.
95.
A new scheme for two-dimensional parallel data transmission with a femtosecond laser pulse through a single-mode fiber, which is based upon one-dimensional space-time conversion technique in conjunction with code division multiple access (CDMA), is implemented and numerically demonstrated. Since many one-dimensional spatial data, which are encoded with their own M-sequence code, must be embedded in a single pulse, the bit-error rate performance degrades compared with conventional CDMA driven by many unsynchronized pulses. Still, two-dimensional digital images in a 16 bits × 16 bits plane (256-bits parallel data) are successfully transmitted by a single femtosecond laser pulse at an equivalent transmission rate of 1.6 Tbit/s and recovered by spectral holography. 相似文献
96.
Fumihiko Tanaka 《Journal of Polymer Science.Polymer Physics》2003,41(20):2405-2412
Number‐ and weight‐average molecular weight of condensation polymers formed by primary molecules carrying different species of functional groups {Ai} (i = 1, 2, …, s) are derived by cascade theory. These functional groups are allowed to form multiple junctions of variable multiplicity k. The gel point condition is found to be given by ∑ wi/|μw,i + 1/∑ fi ? 1 = 0, where fi is the number of Ai groups specified by the index i on a primary molecule, wi ≡ fi/∑ fi the number fraction of the species i it carries, and |μw,i the weight average multiplicity of the junctions formed by the groups Ai. The explicit form of the molecular weight distribution function is found for the simplest case of two components. Possible application to thermoreversible gelation is suggested. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 2405–2412, 2003 相似文献
97.
Matsuura H Hirai A Yamada F Matsumoto T Kawai T 《Journal of the American Chemical Society》2008,130(15):5002-5003
High-density uniform DNA alignment on a metal substrate is essential for creating sensitive DNA devices. We develop a self-sensing DNA alignment process starting from folded DNA to achieve high-density, uniform DNA alignment on an Au(111) surface. We demonstrate that folded DNA plays a critical role in avoiding DNA aggregation and distributing the DNA uniformly on an Au(111) surface at the greatest density and quality ever attained. We also verify that the distributed, folded DNA can be stimulated to align only when the appropriate buffer flow is applied. This selective self-sensing DNA alignment on an Au surface will be a key technology for creating dynamic DNA sensors and switches. 相似文献
98.
99.
Fumihiko Ozaki Dr. Shunsuke Tanaka YoungHyun Choi Dr. Wataru Osada Kozo Mukai Dr. Mitsuaki Kawamura Dr. Masahiro Fukuda Dr. Masafumi Horio Prof. Dr. Takanori Koitaya Prof. Dr. Susumu Yamamoto Prof. Dr. Iwao Matsuda Prof. Dr. Taisuke Ozaki Prof. Dr. Jun Yoshinobu 《Chemphyschem》2023,24(22):e202300477
Sulfur vacancy on an MoS2 basal plane plays a crucial role in device performance and catalytic activity; thus, an understanding of the electronic states of sulfur vacancies is still an important issue. We investigate the electronic states on an MoS2 basal plane by ambient-pressure X-ray photoelectron spectroscopy (AP-XPS) and density functional theory calculations while heating the system in hydrogen. The AP-XPS results show a decrease in the intensity ratio of S 2p to Mo 3d, indicating that sulfur vacancies are formed. Furthermore, low-energy components are observed in Mo 3d and S 2p spectra. To understand the changes in the electronic states induced by sulfur vacancy formation at the atomic scale, we calculate the core-level binding energies for the model vacancy surfaces. The calculated shifts for Mo 3d and S 2p with the formation of sulfur vacancy are consistent with the experimentally observed binding energy shifts. Mulliken charge analysis indicates that this is caused by an increase in the electronic density associated with the Mo and S atoms around the sulfur vacancy as compared to the pristine surface. The present investigation provides a guideline for sulfur vacancy engineering. 相似文献
100.
By using biomaterials, including monosaccharides and disaccharides, as polymeric stabilizing agents, the cyanoacrylate nanoparticles was prepared respectively, with particles diameter of approximately 200 nm or 300 nm. The new method was applied to load/encapsulate ampicillin (ABPC) and pDNA into nanoparticles. Loading efficiency of ABPC was increased compared to the existing method in which dextran is used as a stabilizer. The pDNA encapusulation rate was 68.7%, by using glucose. 相似文献