全文获取类型
收费全文 | 703篇 |
免费 | 10篇 |
国内免费 | 2篇 |
专业分类
化学 | 498篇 |
晶体学 | 5篇 |
力学 | 7篇 |
数学 | 80篇 |
物理学 | 125篇 |
出版年
2021年 | 3篇 |
2020年 | 7篇 |
2019年 | 12篇 |
2018年 | 10篇 |
2017年 | 6篇 |
2016年 | 5篇 |
2015年 | 15篇 |
2014年 | 20篇 |
2013年 | 48篇 |
2012年 | 33篇 |
2011年 | 44篇 |
2010年 | 32篇 |
2009年 | 29篇 |
2008年 | 40篇 |
2007年 | 34篇 |
2006年 | 35篇 |
2005年 | 48篇 |
2004年 | 46篇 |
2003年 | 26篇 |
2002年 | 33篇 |
2001年 | 14篇 |
2000年 | 8篇 |
1999年 | 6篇 |
1998年 | 9篇 |
1997年 | 8篇 |
1996年 | 16篇 |
1995年 | 7篇 |
1994年 | 5篇 |
1993年 | 5篇 |
1992年 | 4篇 |
1991年 | 6篇 |
1990年 | 3篇 |
1989年 | 5篇 |
1988年 | 3篇 |
1987年 | 5篇 |
1986年 | 5篇 |
1985年 | 7篇 |
1984年 | 12篇 |
1983年 | 4篇 |
1982年 | 4篇 |
1981年 | 3篇 |
1980年 | 5篇 |
1979年 | 4篇 |
1978年 | 5篇 |
1977年 | 9篇 |
1976年 | 3篇 |
1975年 | 5篇 |
1972年 | 6篇 |
1969年 | 4篇 |
1965年 | 2篇 |
排序方式: 共有715条查询结果,搜索用时 31 毫秒
61.
M. Ali HaiderAaron J. Capizzi Mitsuhiro MurayamaSteven McIntosh 《Solid State Ionics》2011,196(1):65-72
La0.6Sr0.4CoxFe1−xO3−δ (LSCF), La0.6Sr0.4Cu0.2Fe0.8O3−δ, Ba0.5Sr0.4Co0.8Fe0.2O3−δ and LaFeO3−δ nanoparticles were synthesized by a reverse micelle procedure. Controlling the size of the micelles through the water:oil phase ratio enabled synthesis of phase pure perovskite particles with average sizes from 14 nm to 50 nm. Small amounts of an impurity phase, likely cobalt oxide, were detected in the XRD spectrum of high cobalt content samples of LSCF (x = 0.8). La0.6Sr0.4Co0.2Fe0.8O3−δ nanoparticles were utilized to coat the surface of a dense thin-film La0.6Sr0.4Co0.2Fe0.8O3−δ solid oxide fuel cell cathode. The polarization resistance of the nanoparticle coated electrode, measured at open circuit in air at 973 K, was 20% lower than an equivalent un-coated electrode. 相似文献
62.
Akira Zenidaka Toshiyuki Honda Mitsuhiro Terakawa 《Applied Physics A: Materials Science & Processing》2011,105(2):393-398
We describe the physics of the SERS based on the optical near-field intensity enhancement on the metallic (plasmonic) and
the nonmetallic (Mie scattering) nanostructured substrates with two-dimensional (2D) periodic nanohole arrays. The calculation
by the Finite-Difference Time-Domain (FDTD) method revealed that the optical intensity enhancement increases with the increase
of the thickness of a gold film coating on the nonmetallic (dielectric) nanostructured Si, GaAs, and SiC substrates. The resonance
spectrum shifts with the changes in the geometrical structure of the void diameter and inter-void distance. It was clarified
that the optical intensity enhancement obtained with the gold-coated substrate is equivalent to that with a gold substrate
at 70-nm thick gold coating on the dielectric substrates in this structure. The resonance spectral bandwidth for Mie scattering
and plasmonic near-fields is different. Therefore, if the Stokes line of the Raman scattering is located within the resonance
bandwidth, the SERS signal is enhanced proportionally to the fourth power of the electric near-field. However, if the Stokes
shift is located out of the resonance bandwidth, the SERS signal enhancement is only proportional to the square of the scattered
near-field. 相似文献
63.
Amal Kaddoumi Mitsuhiro Wada Kenichiro Nakashima 《Biomedical chromatography : BMC》2011,25(5):579-587
N‐Nitrosofenfluramine (N‐Fen), a synthetic adulterant in Chinese herbal diet products, is believed to cause hepatotoxicity in people who use these products. N‐Fen is a relatively new compound, and thus pharmacological and toxicological studies are insufficient. The aim of this work was to (1) define N‐Fen's plasma pharmacokinetics and tissue distribution after single intraperitoneal (i.p.) administration of 25 mg/kg to rats; (2) define its bioavailability; and (3) identify fenfluramine (Fen) and norfenfluramine (Norf) as N‐Fen metabolites. N‐Fen rapidly appeared in the circulation and was distributed to all tissues. Norf was found to be the primary metabolite and not Fen. Plasma and tissue levels of N‐Fen and Norf were low with bioavailability of N‐Fen after i.p. administration was <3%. The AUC0−t of N‐Fen in the liver and kidney were 6.6 and 12.1 times, respectively, greater than the brain, and 17.8 and 32.6 times, respectively, greater than the plasma. In conclusion, N‐Fen did not show local accumulation in the liver, the site of toxicity, with concentrations represented as percentage of the total dose ranginng from 0.008 to 0.122%; hence the cause of hepatotoxicity could be related to the mechanisms other than toxicity consequences accumulation. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
64.
65.
66.
Mitsuhiro Hirata Yutaka Abe Bungo Ochiai Takeshi Endo 《Journal of polymer science. Part A, Polymer chemistry》2010,48(20):4385-4392
Various star‐shaped poly(phenoxy propylene sulfide)s (PPSs) bearing curable end groups were synthesized by the functionalization of the propagating ends of star‐shaped poly(PPS) with various electrophilies. The functionalization with chloromethyl styrene proceeded quantitatively, and afforded polymers with Mn almost agreed with theoretical value and narrow Mw/Mn. The photocuring conditions were optimized, and the addition of 10 wt % of poly(ethylene glycol) diacrylate was effective to attain sufficient crosslinking. The photocuring reaction of the end‐functionalized poly(PPS) films cast on silicon wafers was conducted by UV irradiation. The cured poly (PPS)s became insoluble in THF, supporting the sufficient crosslinking. Developing of a cured polymer yielded a negative photoresist pattern. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010 相似文献
67.
Katsuhiko Takenaka Natsuyo Shibata Akihiko Oshikiri Masamitsu Miya Hiroki Takeshita Tomoo Shiomi 《Journal of polymer science. Part A, Polymer chemistry》2010,48(17):3714-3721
Anionic polymerizations of three 1,3‐butadiene derivatives containing different N,N‐dialkyl amide functions, N,N‐diisopropylamide (DiPA), piperidineamide (PiA), and cis‐2,6‐dimethylpiperidineamide (DMPA) were performed under various conditions, and their polymerization behavior was compared with that of N,N‐diethylamide analogue (DEA), which was previously reported. When polymerization of DiPA was performed at ?78 °C with potassium counter ion, only trace amounts of oligomers were formed, whereas polymers with a narrow molecular weight distribution were obtained in moderate yield when DiPA was polymerized at 0 °C in the presence of LiCl. Decrease in molecular weight and broadening of molecular weight distribution were observed when polymerization was performed at a higher temperature of 20 °C, presumably because of the effect of ceiling temperature. In the case of DMPA, no polymer was formed at 0 °C and polymers with relatively broad molecular weight distributions (Mw/Mn = 1.2) were obtained at 20 °C. The polymerization rate of PiA was much faster than that of the other monomers, and poly(PiA) was obtained in high yield even at ?78 °C in 24 h. The microstructure of the resulting polymers were exclusively 1,4‐ for poly(DMPA), whereas 20–30% of the 1,2‐structure was contained in poly(DiPA) and poly(PiA). © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 3714–3721, 2010 相似文献
68.
69.
Mitsuhiro T. Nakao Yoshitaka Watanabe 《Journal of Computational and Applied Mathematics》1994,50(1-3):401-410
This paper is an extension of the preceding study (Nakao, this journal, 1991) in which we described a numerical verification method of the solution for one-space dimensional parabolic problems, to the several-space dimensional case. Here, numerical verification means the automatic proof of the existence of solutions to the problems by some numerical techniques on a computer. We reformulate the verification condition for nonlinear parabolic initial boundary value problems using the fixed-point problem of a compact operator on certain function spaces. As in the preceding study based upon a simple C0 finite-element approximation and its constructive a priori error estimates, a numerical verification procedure is presented with some numerical examples. 相似文献
70.
A combination of gradient reversed-phase high performance liquid chromatography (RP/HPLC) with a radioreceptor assay detector that uses two ligands is used to obtain effectively the metabolic profile of endogenous receptoractive opioid peptides in the canine pituitary and in seven selected brain regions including the hypothalamus, caudate nucleus, mid-brain, amygdala, thalamus, pons-medulla, and the hippocampus. Gradient RP/HPLC separates a mixture of endogenous peptides over a wide range of hydrophobicities. A novel opioid preparation from canine limbic system synaptosomes is utilized in a radioreceptorassay screen; tritiated etorphine (ET) or D-2ala, D-5leuleucine enkephalin (DADL) is used as the competitively displaced ligand. This receptor-rich preparation contains several receptor types, and thus serves well as a screen with the required low level of specificity. Subsequent analysis with other detectors of high specificity (MS, RIA) will follow this screen in other studies. Etorphine interacts with several of the opioid peptide-preferring receptors, whereas DADL is more specific towards the delta receptor that preferentially binds the smaller pentapeptides of the enkephalin family. The highest amount of peptide receptor activity found in this study is in the pituitary tissue, a smaller amount in the hypothalamus and caudate nucleus, and still lower amounts in the other five brain tissue extracts. This variation in peptide concentration most probably reflects three separate factors that operate in this biologic system: differential tissue-specific processing patterns of the large peptide precursors; distribution of the three opioid peptide systems; and the receptor preparation and the radioligand used in the assay. The structures of the receptoractive compounds in each RP/HPLC peak await mass spectrometric confirmation. 相似文献