全文获取类型
收费全文 | 134篇 |
免费 | 7篇 |
专业分类
化学 | 105篇 |
晶体学 | 1篇 |
力学 | 3篇 |
数学 | 6篇 |
物理学 | 26篇 |
出版年
2022年 | 1篇 |
2021年 | 2篇 |
2020年 | 3篇 |
2019年 | 4篇 |
2018年 | 1篇 |
2017年 | 3篇 |
2016年 | 5篇 |
2015年 | 4篇 |
2014年 | 2篇 |
2013年 | 9篇 |
2012年 | 8篇 |
2011年 | 10篇 |
2010年 | 3篇 |
2009年 | 6篇 |
2008年 | 9篇 |
2007年 | 9篇 |
2006年 | 5篇 |
2005年 | 7篇 |
2004年 | 13篇 |
2003年 | 4篇 |
2002年 | 7篇 |
2001年 | 5篇 |
2000年 | 5篇 |
1999年 | 1篇 |
1995年 | 4篇 |
1994年 | 1篇 |
1992年 | 2篇 |
1986年 | 2篇 |
1984年 | 1篇 |
1979年 | 1篇 |
1977年 | 1篇 |
1976年 | 1篇 |
1975年 | 1篇 |
1970年 | 1篇 |
排序方式: 共有141条查询结果,搜索用时 0 毫秒
71.
Shinobu Miyagawa Masaki Kimura Shin Kagami Tsuneomi Kawasaki Yuji Tokunaga 《化学:亚洲杂志》2020,15(19):3044-3049
A crown ether/amine‐type [2]rotaxane was synthesized and utilized as a probe for the detection of acids and anions. The addition of acids to the amine‐type [2]rotaxane solution generated corresponding crown ether/ammonium‐type [2]rotaxanes, which were purified by silica gel column chromatography as ammonium salts. The isolated yields of the [2]rotaxanes, possessing a variety of anions, depended on the acidity and polarity of the counter anions. The behaviours of the ammonium‐type [2]rotaxanes on thin‐layer chromatography (TLC) silica gel reflected the properties of the counter anions. The treatment of the amine‐type [2]rotaxane with acids afforded the corresponding ammonium‐type [2]rotaxanes bearing several different anions. The ammonium‐type [2]rotaxanes behaved similarly to the purified [2]rotaxanes on the TLC silica gel. Furthermore, we succeeded in the analysis of anions using mixtures of the amine‐type [2]rotaxane and salts in an appropriate solvent. We demonstrated the detection of anions by the combination of TLC and the utilization of the [2]rotaxane probe. 相似文献
72.
6-Deoxoteasterone, a brassinolide biosynthetic intermediate, and its 20-epimer were synthesized from steroidal 17-olefin and chiral α-alkoxyaldehyde using a Lewis acid mediated carbonyl-ene reaction as the key step. In this reaction, unusual stereoselectivity was observed. 相似文献
73.
Yamagishi Y Shoji I Miyagawa S Kawakami T Katoh T Goto Y Suga H 《Chemistry & biology》2011,18(12):1562-1570
Naturally occurring peptides often possess macrocyclic and N-methylated backbone. These features grant them structural rigidity, high affinity to targets, proteolytic resistance, and occasionally membrane permeability. Because such peptides are produced by either nonribosomal peptide synthetases or enzymatic posttranslational modifications, it is yet a formidable challenge in degenerating sequence or length and preparing libraries for screening bioactive molecules. Here, we report a new means of synthesizing a de novo library of “natural product-like” macrocyclic N-methyl-peptides using translation machinery under the reprogrammed genetic code, which is coupled with an in vitro display technique, referred to as RaPID (random nonstandard peptides integrated discovery) system. This system allows for rapid selection of strong binders against an arbitrarily chosen therapeutic target. Here, we have demonstrated the selection of anti-E6AP macrocyclic N-methyl-peptides, one of which strongly inhibits polyubiqutination of proteins such as p53. 相似文献
74.
Programmed-temperature retention indices (PTRIs) are useful for the identification and quantification of chemicals by means of GC and GC/MS. To obtain reproducible PTRIs, we studied the influence of average linear velocity and column length under the constant average linear velocity control (CVC) using 55 pesticides and 33 fatty acid methyl esters. The PTRIs decreased with increasing average linear velocity, and the degree of decrease differs with the compounds. The PTRIs, however, were almost constant as long as the same average linear velocity was used even if the column length was changed. In addition, the correlation between the variation ratio in PTRI and the increase in average linear velocity was linear. Using the linear relationship between PTRIs and average linear velocities under CVC, highly reproducible PTRIs were obtained even if the capillary column length changes. Furthermore, the PTRIs determined by GC with FID, ECD, and FPD under atmospheric pressure were applied to GC/MS under vacuum or vice versa. From these results, it was confirmed that because CVC provides reproducible retention indices, CVC is advantageous for qualitative and quantitative analysis by GC and GC/MS. 相似文献
75.
Dr. Masamichi Miyagawa Masaru Yoshida Yuki Kiyota Prof. Dr. Takahiko Akiyama 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(22):5677-5681
An enantioselective Friedel–Crafts alkylation reaction of pyrroles and indoles with N-unprotected trifluoromethyl ketimines by use of chiral phosphoric acid provided α-trifluoromethylated primary amines bearing chiral tetrasubstituted carbon centers in high yields and with high to excellent enantioselectivities. The present reaction is unique to N-unprotected trifluoromethyl ketimines. No reaction took place with N-p-methoxyphenyl (PMP)-substituted ketimine. Corresponding α-trifluoromethylated amines were transformed without loss of enantioselectivity. 相似文献
76.
Dabing Li Bei Ma Reina Miyagawa Weiguo Hu Mitsuhisa Narukawa Hideto Miyake Kazumasa Hiramatsu 《Journal of Crystal Growth》2009,311(10):2906-2909
Si-doped a-plane GaN films with different doping concentrations were grown by metal-organic vapor phase epitaxy. A mirrorlike surface without pits or anisotropic stripes was observed by optical microscopy. Detailed optical properties of the samples were characterized by temperature- and excitation-intensity-dependent PL measurements. A series of emission peaks at 3.487, 3.440, 3.375–3.350, 3.290 and 3.197 eV were observed in the low-temperature PL spectra of all samples. The origin of these emissions is discussed in detail. 相似文献
77.
Takashi Kawakami Koichi Miyagawa Sandeep Sharma Toru Saito Mitsuo Shoji Satoru Yamada Shusuke Yamanaka Mitsutaka Okumura Takahito Nakajima Kizashi Yamaguchi 《Journal of computational chemistry》2019,40(2):333-341
Both direct exchange and super-exchange interactions cooperate to realize inter-spin magnetic interaction in binuclear manganese complex Mn(IV)2O2(NHCHCO2)4 with a di-μ-oxo path. We revisited this spin system using DMRG CAS methods and CAS selection procedures. Our results indicate that our previous “dynamically extended spin polarization” (DE-SP) procedure for organic polyradicals and so forth does not work well. Thus, we have examined another selection procedure, the “dynamically extended super-exchange” (DE-SE) procedure. DMRG CASCI [18,18] by UB3LYP(HS)-UNO(DE-SE) can realize antiferromagnetic J values similar to experimental ones (−87 cm−1). In addition, all J values between all spin states (HS[septet],IS[quintet],IS[triplet],LS[singlet])were also shown to be correct under sufficiently large M values. © 2018 Wiley Periodicals, Inc. 相似文献
78.
Yushin Shibuya Naoki Nakagawa Naoki Miyagawa Toyoko Suzuki Kentaro Okano Atsunori Mori 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(28):9647-9650
The unprecedented synthesis of regioregular head‐to‐tail‐type poly(1,4‐arylene)s bearing different substituents at the 2‐ and 5‐positions is described. They were prepared by the polymerization of 2,5‐disubstituted bromo(chloro)arylenes by selective halogen–metal exchange with a Grignard reagent and subsequent cross‐coupling polymerization with a nickel catalyst [NiCl2(dppp)]. Formation of the regioregular poly(1,4‐arylene)s were confirmed by NMR spectroscopy, and showed remarkable differences to those polymers having uncontrolled regioregularity. Polymerization of bromo(chloro)arylenes with a chiral alkoxy substituent also led to the regioregular head‐to‐tail‐type polyarylene, which demonstrated circular dichroism, thus suggesting formation of a structure with higher‐order regularity. 相似文献
79.
80.