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91.
An analyzer able to detect extremely small concentrations of dideuterium in diprotium gas was developed. To examine its performance, four gas samples of pure diprotium with dideuterium concentrations of 0.25, 0.5, 1, and 5 cm(3)/m(3) were measured using the analyzer, and peak areas and retention times from 18 chromatograms were determined. Results indicated that the peaks were distributed within a relative standard deviation of approximately 15% and a linear correlation existed between peak area and concentration. Retention times were stable, showing a relative standard deviation of 1% with repeated tests and having no correlation with concentration of the four gas samples. 相似文献
92.
Murakami Y Yoshimoto N Fujieda N Ohkubo K Hasegawa T Kano K Fukuzumi S Itoh S 《The Journal of organic chemistry》2007,72(9):3369-3380
The electronic effects of the C-4 substituent on the physicochemical properties and reactivity of the 6,7-inodolequinone cofactors (CTQ and TTQ) have extensively been investigated with use of a series of C-4 substituted 6,7-inodolequinone derivatives (1-4). The one-electron reduction potentials of the 6,7-inodolequinone derivatives decrease with increasing the electron donating ability of the C-4 substituent (with the following order of E degrees': 4>1>2>3). The reaction of indolequinones 1-3 with benzylamine proceeds stepwise through the iminoquinone and the product-imine intermediates to give aminophenol as the final product as the case of TTQ model compound 4. The rate constants of each step have been determined by the detailed kinetic analysis, and the kinetic deuterium isotope effects have also been examined to confirm the rate-determining step. The reactivity of CTQ model compound 1 toward the amines is by one order of magnitude lower than that of TTQ model compound 4. The reactivity of indolequinones 2 and 3 is further decreased due to their stronger electron-donating substituents at C-4. A more important difference between CTQ model compound 1 and TTQ model compound 4 is the reactivity of the iminoquinone intermediate: the reaction of the CTQ model compound with amines stops at the iminoquinone formation stage at room temperature, whereas the reaction of the TTQ model compound with amines proceeds up to the aminophenol formation. Thus, the energy barrier for the rearrangement of the iminoquinone to the product-imine is higher in the CTQ model system than in the TTQ model system. 相似文献
93.
A multicomponent synthesis of biologically important indenes bearing three substituent groups at the 1-, 2-, and 3-positions from available o-ethynylbenzaldehyde derivatives and organoboron reagents under palladium(0) catalysis is described. A two-component coupling reaction in methanol provides 1H-indenols, whereas a three-component reaction involving secondary aliphatic amines as the third component in DMF affords 1H-indenamines. This method allows combinatorial preparation of unsymmetrically substituted 1H-indenes that cannot be prepared via previous synthetic routes. 相似文献
94.
95.
Seiya Fukagawa Yoshimi Kato Ryo Tanaka Masahiro Kojima Tatsuhiko Yoshino Shigeki Matsunaga 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(4):1165-1169
Recent advances in CpxMIII catalysis (M=Co, Rh, Ir) have enabled a variety of enantioselective C(sp2)?H functionalization reactions, but enantioselective C(sp3)?H functionalization is still largely unexplored. We describe an asymmetric C(sp3)?H amidation of thioamides using an achiral CoIII/chiral carboxylic acid hybrid catalytic system, which provides easy and straightforward access to chiral β‐amino thiocarbonyl and β‐amino carbonyl building blocks with a quaternary carbon stereocenter. 相似文献
96.
Juan Hong Xuxian Xiao Haoliang Liu Evgenia Dmitrieva Alexey A. Popov Zidong Yu Prof. Ming-De Li Dr. Tatsuhiko Ohto Jun Liu Prof. Akimitsu Narita Pengcai Liu Prof. Hirokazu Tada Prof. Xiao-Yu Cao Prof. Xiao-Ye Wang Yingping Zou Prof. Klaus Müllen Prof. Yunbin Hu 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(58):e202202243
We present here the synthesis and in-depth physicochemical characterization of a double hetero[7]helicene fused with four triazole rings at both helical ends. The comparison of this triazole-fused double helicene with the previously reported all-carbon and thiadiazole-fused analogs revealed the huge impact of the embedded aromatic rings on the photophysical features. The small structural variation of the terminal rings from thiadiazole to triazole caused a dramatic change of the photoluminescence quantum yields (PLQYs) from <1 % to 96 %, while the replacement of the terminal benzene rings with triazole rings induced a tenfold enhancement of the circularly polarized luminescence dissymmetry factor. These observations were well corroborated with transient absorption analysis and/or theoretic calculations. In addition, the triazole-fused double helicene exhibited ambipolar redox behavior, enabling the generation of radical cation and anion species by electrochemical and chemical methods and showing its potential for spin-related applications. 相似文献
97.
Sasaki S Bando T Minoshima M Shimizu T Shinohara K Takaoka T Sugiyama H 《Journal of the American Chemical Society》2006,128(37):12162-12168
We designed and synthesized pyrrole (Py)-imidazole (Im) hairpin polyamide 1-(chloromethyl)-5-hydroxy-1,2-dihydro-3H-benz[e]indole (seco-CBI) conjugates 1 and 2, which target both strands of the double-stranded region of the human telomere repeat sequences, 5'-d(TTAGGG)(n)-3'/5'-d(CCCTAA)(n)-3'. High-resolution denaturing polyacrylamide gel electrophoresis demonstrated that conjugates 1 and 2 alkylated DNA at the 3' A of 5'-ACCCTA-3' and 5'-AGGGTTA-3', respectively. Cytotoxicities of conjugates 1 and 2 were evaluated using 39 human cancer cell lines; averages of log IC(50) values for conjugates 1 and 2 were -6.96 (110 nM) and -7.24 (57.5 nM), respectively. Conjugates 1 and 2 have potential as antitumor drugs capable of targeting telomere repeat sequence. 相似文献
98.
Esterifying chains of chlorophyllous pigments play important roles in the formation of photosynthetic supramolecules, but their effects have not thoroughly been unraveled yet. Substitution of the esterifying chains in these pigments will be one possible strategy to elucidate this enigma. Recently, unnatural bacteriochlorophylls (BChls) c possessing a hydroxy group at the terminus of the esterifying chains were successfully biosynthesised in the green sulfur bacterium Chlorobaculum (Cba.) tepidum grown by supplementation of α,ω-diols. In this paper, in vitro assembling behaviours of unnatural BChls c isolated from Cba. tepidum grown with 1,8-octanediol, 1,12-dodecanediol and 1,16-hexadecanediol were characterised in aqueous Triton X-100 micelles to investigate the effects of the terminal hydroxy group in the esterifying chains of BChls c on self-aggregates such as chlorosomes, major antenna complexes in green photosynthetic bacteria. The bacteriochlorophyll (BChl) c derivatives monoesterified with α,ω-diols formed chlorosomal self-aggregates, but their formations were much slower than those of natural BChl c. The Qy absorption bands of the residual monomers of these BChl c derivatives were larger than those of natural BChl c. These suggest that the esterifying α,ω-diols in these unnatural BChls c somewhat interfered with formation of chlorosome-like aggregates compared with the natural esterifying farnesol. 相似文献
99.
Hideya Ikemoto Ryo Tanaka Dr. Ken Sakata Prof. Dr. Motomu Kanai Dr. Tatsuhiko Yoshino Prof. Dr. Shigeki Matsunaga 《Angewandte Chemie (International ed. in English)》2017,56(25):7156-7160
A highly atom economical and stereoselective synthesis of tetrasubstituted α,β-unsaturated amides was achieved by a Cp*CoIII-catalyzed C−H alkenylation/directing group migration sequence. A carbamoyl directing group, which is typically removed after C−H functionalization, worked as an internal acylating agent and migrated onto the alkene moiety of the product. The directing group migration was realized with the Cp*CoIII catalyst, while a related Cp*RhIII catalyst did not promote the migration process. The product was further converted into two types of tricyclic compounds, one of which had fluorescent properties. 相似文献
100.
Yudai Suzuki Bo Sun Ken Sakata Tatsuhiko Yoshino Shigeki Matsunaga Motomu Kanai 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2015,127(34):10082-10085
The unique reactivity of [Cp*CoIII] over [Cp*RhIII] was demonstrated. A cationic [Cp*CoIII] catalyst promoted direct dehydrative C H allylation with non‐activated allyl alcohols, thus giving C2‐allylated indoles, pyrrole, and phenyl‐pyrazole in good yields, while analogous [Cp*RhIII] catalysts were not effective. The high γ‐selectivity and C2‐selectivity indicated that the reaction proceeded by directing‐group‐assisted C H metalation. DFT calculations suggested that the γ‐selective substitution reaction proceeded by C H metalation and insertion of a C C double bond, with subsequent β‐hydroxide elimination. The [Cp*CoIII] catalyst favored β‐hydroxide elimination over β‐hydride elimination. 相似文献