全文获取类型
收费全文 | 1697篇 |
免费 | 49篇 |
国内免费 | 8篇 |
专业分类
化学 | 1135篇 |
晶体学 | 13篇 |
力学 | 26篇 |
数学 | 122篇 |
物理学 | 458篇 |
出版年
2023年 | 14篇 |
2022年 | 16篇 |
2021年 | 12篇 |
2020年 | 16篇 |
2019年 | 21篇 |
2018年 | 17篇 |
2017年 | 9篇 |
2016年 | 38篇 |
2015年 | 33篇 |
2014年 | 38篇 |
2013年 | 70篇 |
2012年 | 75篇 |
2011年 | 96篇 |
2010年 | 56篇 |
2009年 | 55篇 |
2008年 | 100篇 |
2007年 | 98篇 |
2006年 | 87篇 |
2005年 | 93篇 |
2004年 | 63篇 |
2003年 | 56篇 |
2002年 | 41篇 |
2001年 | 38篇 |
2000年 | 44篇 |
1999年 | 27篇 |
1998年 | 17篇 |
1997年 | 17篇 |
1996年 | 33篇 |
1995年 | 11篇 |
1994年 | 20篇 |
1993年 | 21篇 |
1992年 | 25篇 |
1991年 | 17篇 |
1990年 | 23篇 |
1989年 | 32篇 |
1988年 | 29篇 |
1987年 | 24篇 |
1986年 | 27篇 |
1985年 | 26篇 |
1984年 | 29篇 |
1983年 | 14篇 |
1982年 | 13篇 |
1981年 | 25篇 |
1980年 | 15篇 |
1979年 | 9篇 |
1978年 | 19篇 |
1977年 | 11篇 |
1976年 | 15篇 |
1975年 | 18篇 |
1973年 | 16篇 |
排序方式: 共有1754条查询结果,搜索用时 31 毫秒
91.
92.
Hui Zhao Shinji Mitsuiki Mikako Takasugi Masashi Sakai Masatoshi Goto Hiroaki Kanouchi Tatsuzo Oka 《Applied biochemistry and biotechnology》2012,166(7):1758-1768
Insoluble and hard-to-degrade animal proteins are group of troublesome proteins, such as collagen, elastin, keratin, and prion proteins that are largely generated by the meat industry and ultimately converted to industrial wastes. We analyzed the ability of the abnormal prion protein-degrading enzyme E77 to degrade insoluble and hard-to-degrade animal proteins including keratin, collagen, and elastin. The results indicate that E77 has a much higher keratinolytic activity than proteinase K and subtilisin. Maximal E77 keratinolytic activity was observed at pH 12.0 and 65 °C. E77 was also adsorbed by keratin in a pH-independent manner. E77 showed lower collagenolytic and elastinolytic specificities than proteinase K and subtilisin. Moreover, E77 treatment did not damage collagens in ovine small intestines but did almost completely remove the muscles. We consider that E77 has the potential ability for application in the processing of animal feedstuffs and sausages. 相似文献
93.
Fukumoto K Sakai A Oya T Nakazawa H 《Chemical communications (Cambridge, England)》2012,48(32):3809-3811
Desulfurization of N,N-dimethylthioformamide (Me(2)NCHS) by hydrosilane has been achieved under photo irradiation in the presence of a methyl iron complex. The reaction sequences have been proposed, in which silyl migration from Fe to S of thioformamide triggers the cleavage of a C=S bond to give a carbene-iron complex. This intermediate was isolated and characterized by X-ray analysis. 相似文献
94.
The first catalytic version of hypervalent aryl-λ(3)-iodane-induced Hofmann rearrangement of primary carboxamides, which probably involves in situ generation of a tetracoordinated bis(aqua)(hydroxy)phenyl-λ(3)-iodane complex as an active oxidant from a catalytic amount of iodobenzene by the reaction with m-chloroperbenzoic acid in the presence of HBF(4) in dichloromethane-water under mild conditions, was developed. 相似文献
95.
Nakanishi S Sakai S Nishimura K Nakato Y 《The journal of physical chemistry. B》2005,109(40):18846-18851
Electrochemical deposition of copper (Cu) from aqueous acidic Cu2+ solutions with o-phenanthroline (o-phen) shows both potential and current oscillations, together with a (partially hidden) N-shaped negative differential resistance (N-NDR), indicating that the oscillations are classified into hidden N-NDR (or HN-NDR) oscillations. The color and the surface morphology of Cu deposits oscillate in synchronization with the potential and current oscillations. Microscopic inspection has shown that dense round Cu leaflets, which look gray, grow in the positive side of the potential oscillation or in the high-current state of the current oscillation, whereas thin Cu leaflets, which look black, grow in the opposite-side stages of the potential and current oscillations, thus finally resulting in a layered Cu deposit with the layer thickness of about 5 microm. The appearance of the NDR is explained to be due to adsorption of the reduced form of a [Cu(II)(o-phen)2]2+ complex, which suppresses the Cu electrodeposition. The increase in the effective electrode surface area by growth of thin Cu leaflets, on the other hand, causes a current increase that can hide the NDR. This NDR-hiding mechanism is of a new type and the present oscillation is regarded as a new-type of HN-NDR oscillator. 相似文献
96.
Imai M Sakai K Kikuchi M Nakaya K Saeki A Teramoto T 《The Journal of chemical physics》2005,122(21):214906
We have investigated the structural development during order-order transitions to the double-gyroid (DG) phase of nonionic surfactant/water systems based on two-dimensional small-angle x-ray scattering patterns from highly oriented ordered mesophases. The lamellar (L) to DG transition proceeds through two intermediate structures, a fluctuating perforated layer structure having ABAB stacking and a hexagonal perforated lamellar structure with ABCABC stacking (HPLABC). For a hexagonally packed cylinder (H) to DG transition, we also observed the HPLABC structure as the intermediate phase, thus the HPLABC is an entrance structure for the DG phase. The hexagonal perforated lamellar (HPL) structure consists of hexagonally packed holes surrounded by the planar tripods, and the transition from HPL structure to the DG phase proceeds by rotation of the dihedral angle of connected tripods. A geometrical consideration shows that large deformations of HPL planes are necessary to form the DG structure from the HPLABC structure, whereas the transition from a HPL structure with ABAB stacking (HPLAB) to the DG structure is straightforward. In spite of the topological constraints, the HPLABC structure is observed in the kinetic pathway to the DG structure. 相似文献
97.
98.
A novel supramolecular graft copolymer(SGP) composed of viologen-containing copolymer(P(DMA-co-diEV)) as the main chain and Np ended PNIPAM(Np-PN1PAm) as the grafts is prepared(DMA:N,N- dimethylacryamide,diEV:ethylviologen dimer,Np:naphthalene,PNIPAM:poly(N-isopropylacrylamide)). The grafting is based on the triple complexation among a host of cucurbit[8]uril(CB[8])and two guests of diEV and Np,which is characterized by UV-vis spectra and ITC.Temperature sensitive property of PNIPAm moiety allows SGP to self-assemble into non-covalently connected micelle(NCCM) at high temperature. The micelles are sensitive to reducing agents,for example Na2S2O3,which breaks the current inclusion complex pair and induces aggregation. 相似文献
99.
100.
Seiichi Miyanaga Hajime Yasuda Akio Hiwara Akira Nakumura Hiroshi Sakai 《高分子科学杂志,A辑:纯化学与应用化学》2013,50(9-11):1347-1361
New types of air-stable metal-carbon composites which contain ultrafine metal particles (Fe, Co, Ni, Pd, Pt, Rh, Cu, etc.) uniformly dispersed in a carbon matrix were obtained by pyrolysis of a variety of soluble organometallic polymers, macromolecular-metal complexes, and blends of coal pitch with metal complexes at 400-1400°C in N2. Some of their unique physical properties and functions are noted. 相似文献