全文获取类型
收费全文 | 1578篇 |
免费 | 56篇 |
国内免费 | 2篇 |
专业分类
化学 | 1327篇 |
晶体学 | 22篇 |
力学 | 12篇 |
数学 | 77篇 |
物理学 | 198篇 |
出版年
2023年 | 11篇 |
2022年 | 16篇 |
2021年 | 26篇 |
2020年 | 20篇 |
2019年 | 29篇 |
2018年 | 20篇 |
2017年 | 17篇 |
2016年 | 34篇 |
2015年 | 25篇 |
2014年 | 40篇 |
2013年 | 87篇 |
2012年 | 76篇 |
2011年 | 105篇 |
2010年 | 48篇 |
2009年 | 49篇 |
2008年 | 116篇 |
2007年 | 116篇 |
2006年 | 105篇 |
2005年 | 144篇 |
2004年 | 97篇 |
2003年 | 67篇 |
2002年 | 70篇 |
2001年 | 24篇 |
2000年 | 19篇 |
1999年 | 10篇 |
1998年 | 24篇 |
1997年 | 15篇 |
1996年 | 26篇 |
1995年 | 11篇 |
1994年 | 12篇 |
1993年 | 7篇 |
1992年 | 5篇 |
1991年 | 8篇 |
1990年 | 4篇 |
1989年 | 11篇 |
1988年 | 5篇 |
1987年 | 4篇 |
1986年 | 6篇 |
1985年 | 12篇 |
1984年 | 14篇 |
1983年 | 6篇 |
1982年 | 20篇 |
1981年 | 10篇 |
1980年 | 17篇 |
1979年 | 6篇 |
1978年 | 12篇 |
1977年 | 8篇 |
1976年 | 5篇 |
1975年 | 5篇 |
1974年 | 6篇 |
排序方式: 共有1636条查询结果,搜索用时 15 毫秒
191.
Hideki Tanemura 《Probability Theory and Related Fields》1996,104(3):399-426
Sumamry An infinite system of Skorohod type equations is studied. The unique solution of the system is obtained from a finite case by passing to the limit. It is a diffusion process describing a system of infinitely many Brownian hard balls and has a Gibbs state associated with the hard core pair potential as a reversible measure.On leave of, Department of Mathematics and Informatics, Faculty of Science Chiba University Chiba, 263 JapanSupported by Swiss National Foundation, contract Nr. 20-36305.92 相似文献
192.
Friendly walkers is a stochastic model obtained from independent one-dimensional simple random walks {S
k
j
}
j≥0
, k=1,2,…,d by introducing ``non-crossing condition': and ``reward for collisions' characterized by parameters . Here, the reward for collisions is described as follows. If, at a given time n, a site in ℤ is occupied by exactly m≥2 walkers, then the site increases the probabilistic weight for the walkers by multiplicative factor exp (β
m
)≥1. We study the localization transition of this model in terms of the positivity of the free energy and describe the location
and the shape of the critical surface in the (d−1)-dimensional space for the parameters .
Received: 13 June 2002 / Revised version: 24 August 2002 Published online: 28 March 2003
Mathematics Subject Classification (2000): 82B41, 82B26, 82D60, 60G50
Key words or phrases: Random walks – Random surfaces – Lattice animals – Phase transitions – Polymers – Random walks 相似文献
193.
Hideki Matsubara Shun-Ichiro Hata Yosuke Kondo Yasuyuki Ishida Hiroshi Takigawa Hajime Ohtani 《Analytical sciences》2006,22(11):1403-1407
The cross-linking structure of the ultra violet (UV)-cured resin prepared from dipentaerithritol hexacrylate (DPHA) was characterized by matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) combined with supercritical methanolysis. The MALDI-mass spectrum of the decomposition products obtained by supercritical methanolysis contained a series of peaks of sodium-cationized methyl acrylate (MA) oligomers up to around m/z = 4000 formed through selective cleavage and methylation occurred at ester linkages in UV-cured DPHA. Furthermore, in order to observe widely distributed sequence lengths in the cross-linking junctions, the decomposed products of the cured resin were then fractionated using size exclusion chromatography followed by the MALDI-MS measurements of the individual fractions. The MALDI-mass spectra of the lower molar mass fractions mainly consisted of a series of peaks of MA oligomers around m/z values of several thousands, whereas those of higher molecular weight showed a broad peak up to m/z ca. 180000. The observed distributions of the supercritical methanolysis products suggested that the network junctions in the given UV-cured resin were composed of up to around 2000 acrylate units. 相似文献
194.
A multi-objective lead time control problem in multi-stage assembly systems using genetic algorithms
Cahit Perkgoz Amir Azaron Hideki Katagiri Kosuke Kato Masatoshi Sakawa 《European Journal of Operational Research》2007
In this paper, we develop a multi-objective model to optimally control the lead time of a multi-stage assembly system, using genetic algorithms. The multi-stage assembly system is modelled as an open queueing network. It is assumed that the product order arrives according to a Poisson process. In each service station, there is either one or infinite number of servers (machines) with exponentially distributed processing time, in which the service rate (capacity) is controllable. The optimal service control is decided at the beginning of the time horizon. The transport times between the service stations are independent random variables with generalized Erlang distributions. The problem is formulated as a multi-objective optimal control problem that involves four conflicting objective functions. The objective functions are the total operating costs of the system per period (to be minimized), the average lead time (min), the variance of the lead time (min) and the probability that the manufacturing lead time does not exceed a certain threshold (max). Finally, we apply a genetic algorithm with double strings using continuous relaxation based on reference solution updating (GADSCRRSU) to solve this multi-objective problem, using goal attainment formulation. The results are also compared against the results of a discrete-time approximation technique to show the efficiency of the proposed genetic algorithm approach. 相似文献
195.
Kozo Matsumoto Hideki Matsuoka 《Journal of polymer science. Part A, Polymer chemistry》2005,43(17):3778-3787
Carbosilane fine particles were synthesized by core‐crosslinking of carbosilane block copolymer micelles and they were pyrolytically transformed into silica nanoparticles. The carbosilane block copolymer, poly(1‐(3‐butenyl)‐1‐methylsilacyclobutane)‐block‐polystyrene, (polyBMSB‐b‐polySt), [(m, n) = (31, 16), (54, 30), and (75, 28)], was synthesized by anionic polymerization of BMSB and St, where m and n represent polymerization degrees of BMSB and St segments, respectively. The block copolymer formed micelles in N,N‐dimethylformamide (DMF). The hydrodynamic diameters (Dh) of the micelles evaluated by dynamic light scattering ranged from 40 to 158 nm depending on the copolymer molecular weight. The core of the micelle was cross‐linked by Pt‐catalyzed hydrosilation with 1,2‐bis(dimethylsilylethane). The Dh of the core‐cross‐linked micelles in THF ranged from 56 to 164 nm. These precursor particles were pyrolyzed at 850 °C under N2 to give ceramic nanoparticles. The diameters of the spherical ceramic particles estimated by AFM ranged from 25 to 60 nm. X‐ray fluorescence analysis of the ceramic products revealed that it consisted of mainly SiO2 rather than SiC. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 3778–3787, 2005 相似文献
196.
Miki Yumoto Takahiro Tamura Taketomo Sato Hideki Hasegawa 《Superlattices and Microstructures》2003,34(3-6):485
In view of applications to hexagonal binary decision diagram (BDD) LSIs, a first attempt is made to form quantum BDD node switches on selectively grown (SG) embedded quantum wires (QWRs) by molecular beam epitaxy (MBE). SG branch switches controlled by a Schottky wrap gate (WPG) were successfully fabricated by MBE growth and subsequent device processing. Gate control characteristics were studied by gate-dependent Shubnikov–de-Haas measurements, and the behavior was found to be similar to that of devices fabricated on wires by etching. The switch exhibited clear conductance quantization at low temperature, and temperature dependence of the voltage slope of conductance jump was clarified. A Y-branch BDD node device using two SG branch switches was successfully fabricated, and realized clear path switching characteristics. 相似文献
197.
Kazuharu Sugawara Naoto Kamiya George Hirabayashi Hideki Kuramitz 《Analytical sciences》2005,21(8):897-900
Avidin, which is one type of glycoprotein, has a strong affinity with biotin (Ka = 10(15) M(-1)). Iminobiotin also forms a complex with avidin (Ka = 10(8) M(-1) at pH 9.5). The avidin-iminobiotin complex changes to the avidin-biotin complex in the presence of biotin because of the difference of the binding constant to avidin. In this study, the interaction between avidin and iminobiotin labeled with an electroactive compound was investigated by voltammetry. After avidin and the labeled iminobiotin (LI) were incubated in 0.1 M phosphate buffer (pH 7.0), the peak currents of LI were measured in various concentrations of biotin. The peak currents increased with increasing the concentration of biotin. Thus, this observation indicates the formation of avidin-biotin complex. On the other hand, the formation of avidin-iminobiotin complex depended on the pH of the solution. LI combines with the avidin at pH 5.6-8.9 and dissociates at pH 4.6. 相似文献
198.
Yasushi Nakamura Michihisa Ito Hideki Ishikawa 《Plasma Chemistry and Plasma Processing》1981,1(2):149-160
A laboratory-scale test was made in which iron oxide contained in a water-cooled crucible was melted and reduced by using a 10–50% H2-Ar transferred arc plasma. The degree of reduction was found to be proportional to the amount of hydrogen fed. The efficiency of hydrogen utilization for the reduction was 50–70%, which is much higher than equilibrium values below 3000 K. This high efficiency was attributable partially to the reactivity of the hydrogen atom in a plasma and partially to the continuous contact of the hydrogen plasma with the molten iron oxide layer floating over the liquid iron formed. During the plasma reduction, evaporative loss of phosphorus was observed. The degree of phosphorus removal depended on the weight ratio, CaO/(SiO2+Al2O3). H2-Ar plasma was shown to be far superior for the phosphorus removal, compared with Ar and Ar-N2 plasma. 相似文献
199.
The ozonolysis of 2-phenyloxazoles having the good leaving group as an anion at C-5 position gave mainly N-benzoylisocyanate ( 2 ) with the formation of carbon dioxide. 相似文献
200.
Hideki Sakurai Yoshiyasu Kamiyama Yasuhiro Nakadaira 《Journal of organometallic chemistry》1977,131(1):147-152
1,1,2,2-Tetramethyl-1,2-disilacyclopentane undergoes the SiSi/SiSi metathesis reaction with vinyl- or ethynyl-substituted disilanes in the presence of a palladium complex. 相似文献