全文获取类型
收费全文 | 930篇 |
免费 | 8篇 |
专业分类
化学 | 594篇 |
晶体学 | 8篇 |
力学 | 10篇 |
数学 | 39篇 |
物理学 | 287篇 |
出版年
2021年 | 7篇 |
2020年 | 9篇 |
2019年 | 13篇 |
2018年 | 9篇 |
2017年 | 9篇 |
2016年 | 20篇 |
2015年 | 13篇 |
2014年 | 15篇 |
2013年 | 28篇 |
2012年 | 37篇 |
2011年 | 45篇 |
2010年 | 34篇 |
2009年 | 26篇 |
2008年 | 48篇 |
2007年 | 50篇 |
2006年 | 34篇 |
2005年 | 38篇 |
2004年 | 33篇 |
2003年 | 42篇 |
2002年 | 50篇 |
2001年 | 29篇 |
2000年 | 35篇 |
1999年 | 13篇 |
1998年 | 16篇 |
1997年 | 16篇 |
1996年 | 17篇 |
1995年 | 18篇 |
1994年 | 13篇 |
1993年 | 8篇 |
1992年 | 14篇 |
1991年 | 18篇 |
1990年 | 15篇 |
1989年 | 8篇 |
1988年 | 10篇 |
1987年 | 7篇 |
1986年 | 12篇 |
1985年 | 12篇 |
1984年 | 11篇 |
1983年 | 5篇 |
1982年 | 10篇 |
1980年 | 10篇 |
1979年 | 6篇 |
1978年 | 8篇 |
1977年 | 9篇 |
1974年 | 6篇 |
1973年 | 6篇 |
1969年 | 5篇 |
1968年 | 5篇 |
1967年 | 6篇 |
1966年 | 5篇 |
排序方式: 共有938条查询结果,搜索用时 15 毫秒
1.
Watanabe Sou Senzaki Tatsuya Shibata Atsuhiro Nomura Kazunori Takeuchi Masayuki Nakatani Kiyoharu Matsuura Haruaki Horiuchi Yusuke Arai Tsuyoshi 《Journal of Radioanalytical and Nuclear Chemistry》2019,322(3):1273-1277
Journal of Radioanalytical and Nuclear Chemistry - Extraction chromatography flow-sheet employing octyl(phenyl)-N,N-diisobutylcarbonoylmethylphosphine oxide and bis(2-ethylhexyl) hydrogen phosphate... 相似文献
2.
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
3.
T Yamakawa H Matsukura Y Nomura M Yoshioka M Masaki H Igata S Okabe 《Chemical & pharmaceutical bulletin》1991,39(7):1746-1752
A series of N-substituted 2-[(2-imidazolylsulfinyl)methyl]anilines (3) was synthesized and evaluated for its biological activity against gastric H+/K(+)-ATPase prepared from rabbit stomach and gastric acid secretions in Heidenhain pouch dogs. Monoalkyl substituents on the nitrogen atom of the aniline moiety markedly inhibited the enzyme activity to the same degree as omeprazole, a representative H+/K(+)-ATPase inhibitor. Most of these compounds, administered at 3 mg/kg i.v. inhibited histamine-stimulated gastric acid secretion. The inhibitory activity of these derivatives on the enzymes at pH 6.0 was more potent than that at pH 7.4, and was distinctly correlated to stability in aqueous solution at pH 5.0. 相似文献
4.
K. M. A. Salam Hidekazu Konishi Masahiro Mizuno Hisashi Fukuda Shigeru Nomura 《Applied Surface Science》2002,190(1-4):88-95
Polycrystalline (1−x)Ta2O5−xTiO2 thin films were formed on Si by metalorganic decomposition (MOD) and annealed at various temperatures. As-deposited films were in the amorphous state and were completely transformed to crystalline after annealing above 600 °C. During crystallization, a thin interfacial SiO2 layer was formed at the (1−x)Ta2O5−xTiO2/Si interface. Thin films with 0.92Ta2O5–0.08TiO2 composition exhibited superior insulating properties. The measured dielectric constant and dissipation factor at 1 MHz were 9 and 0.015, respectively, for films annealed at 900 °C. The interface trap density was 2.5×1011 cm−2 eV−1, and flatband voltage was −0.38 V. A charge storage density of 22.8 fC/μm2 was obtained at an applied electric field of 3 MV/cm. The leakage current density was lower than 4×10−9 A/cm2 up to an applied electric field of 6 MV/cm. 相似文献
5.
6.
Isoprenoid-substituted phenolic compounds of moraceous plants 总被引:3,自引:0,他引:3
7.
Well-defined polarograms of five alkali-metal ions in 0.01M hydrochloric acid were obtained by means of modified normal pulse polarography. The method uses the procedure of anodic stripping chronoamperometry during the life-time of a drop from a dropping mercury electrode, namely preparation of electrode, accumulating step and anodic stripping step of a metal. The instantaneous polarographic currents were sampled only once per mercury drop after the fall of each pulse. The wave heights for alkali-metal ions by the present method are free from the interference caused by 0.01M hydrochloric acid. The present method is applicable to monitoring of alkali-metal ions in fluid acid streams. 相似文献
8.
Ito S Nomura A Morita N Kabuto C Kobayashi H Maejima S Fujimori K Yasunami M 《The Journal of organic chemistry》2002,67(21):7295-7302
The Diels-Alder reaction of di-2-azulenylacetylene with tetraphenylcyclopentadienone afforded 7,8,9,10-tetraphenyldiazuleno[2,1-a:1,2-c]naphthalene in one pot via autoxidation of the presumed 1,2-di-2-azulenylbenzene derivative. In contrast, a similar reaction of bis(1-methoxycarbonyl-2-azulenyl)acetylene with tetraphenylcyclopentadienone gave the 1,2-di-2-azulenylbenzene derivative. The following cyclodehydrogenation reaction of the benzene derivative with iron(III) chloride afforded diazuleno[2,1-a:1,2-c]naphthalene 6,11-bismethoxycarbonyl derivative. The redox behavior of these novel diazuleno[2,1-a:1,2-c]naphthalenes was examined by cyclic voltammetry (CV). These compounds exhibited two-step oxidation waves at +0.22 to +0.71 V upon CV, which revealed the formation of a radical cation and dication stabilized by the fused two azulene rings under the electrochemical oxidation conditions. Since the 1,2-di-2-azulenylbenzene derivative was oxidized at higher oxidation potentials (+0.83 and +1.86 V), the fusion of the two azulene rings to naphthalene increased electron-donating properties because of the formation of a closed-shell dicationic structure. Formation of the radical cation was characterized by UV-vis spectroscopy under the electrochemical oxidation conditions, although no evidence was obtained for the presumed dication under the conditions of the UV-vis spectroscopy measurement. 相似文献
9.
Pavel Smirnov Hisanobu Wakita Masaharu Nomura Toshio Yamaguchi 《Journal of solution chemistry》2004,33(6-7):903-922
The structure and complex formation of concentrated aqueous gallium(III) bromide (GaBr3) solutions have been investigated over a temperature range 80–333 K by Raman spectroscopy, X-ray absorption fine structure (XAFS), and X-ray diffraction. The Raman spectra obtained at various [Br?]/[Ga3+] molar ratios and temperatures have shown that complex formation between Ga3+ and Br? occurs as a predominant species, with [GaBr4]? at [Ga3+] as high as 1~2 M (M = mol?dm ?3) and [Br?]/[Ga3+] ratios > ~2, and that cooling of the solutions favors the formation of the aqua Ga3+. The intermediate species were not seen in the Raman spectra. The XAFS data have revealed that the aqua complex has a sixfold coordination as [Ga(H2O)6]3+ with a Ga3+–H2O distance of (1.96 ± 0.02) Å, whereas the [GaBr4]? complex has a Ga3+–Br? distance of (2.33± 0.02) Å, and that vitrification of the aqueous GaBr3 solution at liquid nitrogen temperature shifts the equilibrium toward the aqua complex. The X-ray diffraction data at different subzero temperatures have shown a tendency of decreasing Ga3+–Br? and increasing Ga3+–H2O interactions with lowering temperature, confirming the preference of aqua Ga3+ in the supercooled liquid state as well as in the glassy state. The Ga3+–H2O distance of ~1.8 Å for the tetrahedral coordination was found in a 2.01 M gallium(III) bromide solution with a [Br?]/[Ga3+] ratio of 3.7 and gradually increased to a value of 1.92 Å for octahedral geometry with decreasing temperature, suggesting that equilibrium shifts from [GaBr4]? to [Ga(H2O)6]3+ through intermediate species, [GaBr n ](3?n)+ (n = 2 and 3). The Ga3+–Br? and Br?–Br? distances within [GaBr4]? with an almost tetrahedral symmetry are (2.35± 0.02) and (3.82± 0.03) Å, respectively. The Ga3+ has the second hydration shell at (4.03± 0.03) Å and the hydration of Br? is characterized with a Br?–H2O distance of (3.35± 0.02) Å at all temperatures investigated. 相似文献
10.
Hiroyuki Ishibashi Motofumi Okada Atsuko Akiyama Kazuyuki Nomura Masazumi Ikeda 《Journal of heterocyclic chemistry》1986,23(4):1163-1166
2,3-Dihydro-5H-1,4-benzoxathiepins were prepared by intramolecular Friedel-Crafts reactions of ethyl α-[2-(aryloxy)ethylthio]-α-chloroacetates or by acid-catalyzed cyclizations of ethyl α-[2-(aryloxy)ethylsulfinyl]-acetate. 1,2,3,5-Tetrahydro-4,1-benzothiazepines were similarly prepared. 相似文献