全文获取类型
收费全文 | 165篇 |
免费 | 1篇 |
国内免费 | 1篇 |
专业分类
化学 | 111篇 |
晶体学 | 1篇 |
力学 | 4篇 |
数学 | 8篇 |
物理学 | 43篇 |
出版年
2023年 | 1篇 |
2022年 | 3篇 |
2021年 | 3篇 |
2020年 | 2篇 |
2019年 | 4篇 |
2016年 | 3篇 |
2015年 | 2篇 |
2014年 | 7篇 |
2013年 | 10篇 |
2012年 | 11篇 |
2011年 | 9篇 |
2010年 | 8篇 |
2009年 | 4篇 |
2008年 | 5篇 |
2007年 | 7篇 |
2006年 | 11篇 |
2005年 | 4篇 |
2004年 | 6篇 |
2003年 | 9篇 |
2002年 | 1篇 |
2001年 | 8篇 |
2000年 | 2篇 |
1999年 | 3篇 |
1998年 | 1篇 |
1995年 | 1篇 |
1993年 | 1篇 |
1992年 | 1篇 |
1991年 | 2篇 |
1990年 | 3篇 |
1989年 | 3篇 |
1988年 | 3篇 |
1986年 | 2篇 |
1984年 | 1篇 |
1982年 | 4篇 |
1981年 | 1篇 |
1979年 | 2篇 |
1978年 | 2篇 |
1977年 | 2篇 |
1976年 | 3篇 |
1975年 | 1篇 |
1974年 | 2篇 |
1973年 | 2篇 |
1972年 | 2篇 |
1968年 | 1篇 |
1967年 | 1篇 |
1966年 | 1篇 |
1965年 | 1篇 |
1961年 | 1篇 |
排序方式: 共有167条查询结果,搜索用时 31 毫秒
71.
Matsushima F Matsunaga M Qian GY Ohtaki Y Wang RL Takagi K 《Journal of Molecular Spectroscopy》2001,206(1):41-46
Frequencies of pure rotational transitions of D(2)O were measured in the region 0.5-5 THz with a high-precision far-infrared spectrometer using a tunable radiation source. Measured frequencies of about 150 spectral lines, 30 of them being newly measured lines, provide an excellent frequency standard for the far-infrared region together with our previous measurements on H(2)(16)O, H(2)(17)O, and H(2)(18)O. Molecular parameters of Watson's A-reduced Hamiltonian have been obtained to reproduce the observed frequencies. Copyright 2001 Academic Press. 相似文献
72.
Shunsuke KurosawaHidetoshi Kubo Kazuki UenoShigeto Kabuki Satoru IwakiMichiaki Takahashi Kojiro TaniueNaoki Higashi Kentaro MiuchiToru Tanimori Dogyun KimJongwon Kim 《Current Applied Physics》2012,12(2):364-368
It is an on-going challenge to verify the proton range in situ during proton therapy. Since the protons stop in target tissue, measurement of gamma-rays emitted either promptly from nuclear de-excitation or in pair from positron annihilation is the feasible method to monitor the proton range in-vivo. Using the technique of gamma collimation, we empirically demonstrated that the proton range and prompt gamma distribution are well correlated in the therapy energy range, and that measuring prompt gammas is a viable method for the clinical application. However, this collimation technique appears not to be applicable to passively scattered proton beams. The device chosen for gamma imaging in 2D is an electron tracking Compton camera, which images single-emission photons employing a gas chamber to induce Compton scattering. Images of prompt gammas were attained at the proton beam energy of 140 MeV. Measurements showed that gamma image in the energy range of 800-2000 keV provides a better match with the proton range compared to the image by lower energy gammas. 相似文献
73.
74.
75.
Kazuko Tanaka Fumiaki Kobayashi Yasuhiro Isogai Tetsutaro Iizuka 《Journal of Electroanalytical Chemistry》1991,321(3):413-421
The oxidation current of superoxide anions generated from a single neutrophil stimulated with Immunoglobulin G or phorbol myristate acetate has been determined with a carbon fibre microelectrode. Superoxide generation by a stimulated porcine or human neutrophil is initiated 1 min after the stimulation, reaches a maximum around 5 min later, and ends within 20 min. The current—time profiles thus determined agreed well to the time-course curves of superoxide generation obtained from conventional techniques using macroscopic numbers of cells. A sampled dc voltammogram of superoxide anions having a redox potential at around −0.3 V vs. Ag/AgCl was obtained using carbon fibre microelectrode. 相似文献
76.
Ratiya Charoensakdi Masaru Iizuka Kazuo Ito Vichien Rimphanitchayakit Tipaporn Limpaseni 《Journal of inclusion phenomena and macrocyclic chemistry》2007,57(1-4):53-59
Recombinant cyclodextrin glycosyltransferase (CGTase) was obtained by cloning the PCR gene fragment from thermotolerant Paenibacillus sp. strain RB01 screened from hot spring area in Thailand and cloned into the Escherichia coli expression vector. The nucleotide sequence was analyzed and aligned. Nucleotide sequence of the recombinant CGTase contained
an open reading frame of 2139 bp encoding 713 amino acid residues. The recombinant required one-third of culture time and
neutral pH to produce CGTase compared to wild type. CGTases from both wild type and transformant were purified in parallel
by starch adsorption and DEAE cellulose column. Their biochemical properties such as molecular weight, optimum pH and temperature
were quite similar. However, the recombinant enzyme showed improved catalytic activity in the coupling reaction between cyclodextrins
(CDs) and some disaccharides. Among several sugars tested with excess βCD, cellobiose was the best substrate followed by leucrose.
Very low activity was observed with trehalose, lactose and mellibiose. Sucrose and raffinose showed no activity. The K
m and other kinetic parameters of recombinant enzyme were determined for cellobiose and several cyclodextrin derivatives. Recombinant
CGTase showed lower K
m for βCD and its derivatives, with improved activity compared to wild type enzyme. 相似文献
77.
Enantioselective microbial hydrolysis of C1 and C2 dissymmetrical cyclic carbonates with disubstitution (methyl and another groups) has been developed. Pseudomonas diminuta (FU0090), a bacterium, efficiently catalyzes the hydrolysis of five-membered cyclic carbonates. While the trans-substrates are hydrolyzed with low enantioselectivities and/or reactivities, the microbe hydrolyzes the cis-substrates with very high enantioselectivities to afford the corresponding almost optically pure anti-(2R,3S)-diols. On the other hand, six-membered trans-cyclic carbonates are enantioselectively hydrolyzed to afford the corresponding optically active syn-(2R,4R)-diols, although the hydrolysis of the cis-substrates gives racemic compounds. In all cases, the enzyme prefers the (R)-enantiomer for the carbon atom bearing a methyl group. 相似文献
78.
Porntida Yampayont Masaru Iizuka Kazuo Ito Tipaporn Limpaseni 《Journal of inclusion phenomena and macrocyclic chemistry》2006,56(1-2):203-207
A Cyclodextrin (CDs) producing bacteria was isolated from waste of starch factory in Thailand and identified as Bacillus circulans by biochemical characterization and Paenibacillus sp. by 16S rRNA. The Paenibacillus grew and produced cyclodextrin glycosyltransferase (CGTase) at temperature range 37–45 °C. The optimum culturing conditions for highest CD-forming activity were pH 10.0 and 40 °C for 72 h in Horikoshi broth containing 0.5% soluble starch. The CGTase was partially purified by starch absorption, with 64% recovery and purification fold of 27. The optimum temperatures for dextrinizing and CD-forming activity were 70 and 50–55 °C. At the optimum temperature, the optimum pH for dextrinizing activity was 6.0, while CD-forming activity was 7.0. When the enzyme was incubated for 1 h at different temperatures, CD-forming activity retained its full activity up to 70 °C while dextrinizing activity dropped to 60%. Cyclodextrin products analyzed by HPLC was α:β=1:1, temperature of reaction mixture can affect the yield of CDs. 相似文献
79.
E. Rodenas T. Iizuka H. Katsumata K. Tanabe 《Reaction Kinetics and Catalysis Letters》1982,19(3-4):341-344
The support and mixing effects of Fe2O3 for the activity of 1-butene oxidative dehydrogenation were examined. Alumina and titania which were able to catalyze the isomerization of butene via an allyl intermediate, stimulated remarkably the formation of butadiene from butene when they were used as support or mixing component of Fe2O3 catalyst. Otherwise Fe2O3 supported on SO
4
2–
ion containing Al2O3 or TiO2–Al2O3, which catalyze the isomerization via a cationic intermediate, is almost inactive for the formation of butadiene.
Fe2O3 1-. , , , Fe2O3. , Fe2O3, Al2O3, SO 4 –2 , TiO2–Al2O3, , .相似文献
80.
Makoto Ojika Prof. Yasutaka Inukai Yuko Kito Masayuki Hirata Takashi Iizuka Dr. Ryosuke Fudou Dr. 《化学:亚洲杂志》2008,3(1):126-133
Marine myxobacteria are rare culture‐resistant microorganisms, several strains of which have been identified by research groups in Asia. Paraliomyxa miuraensis, a slightly halophilic myxobacterium discovered in Japan, produces the cyclic hybrid polyketide–peptide antibiotics known as miuraenamides A and B, whose taxonomical and biological characteristics have been reported previously. Herein, we describe the chemical characterization of these two miuraenamides and introduce four new members of the miuraenamide family. We carried out the complete structural analysis of miuraenamides A and B on the basis of NMR spectroscopic analysis and elucidated the absolute configuration of miuraenamide A by chemical derivatization and subsequent use of the modified Mosher method or the Marfey method. Miuraenamides C–F were isolated from the same strain of the bacterium as miuraenamides A and B. The structure–antimicrobial‐activity relationships of the six natural metabolites and four chemically derived compounds demonstrated the importance of both the macrocyclic structure and the β‐methoxyacrylate moiety. 相似文献