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41.
M Albrecht Y Shang K Hasui V Gossen G Raabe K Tahara Y Tobe 《Dalton transactions (Cambridge, England : 2003)》2012,41(31):9316-9322
Triangular triscatechol ligands are prepared in facile reaction sequences. The catechol units are either bound to the triangular backbone through their 3- or 4-position. With titanium(IV) ions, the ligands form metallosupramolecular M(4)L(4) tetrahedra which are characterized by ESI MS and proton NMR. Quantum-chemical calculations reveal that connectivity at the catechol in the 3-position results in highly condensed structures while attachment in the 4-position affords container molecules providing huge internal cavities. 相似文献
42.
43.
Dr. Masafumi Ueda Akimi Tahara Dr. Masashi Hasegawa Dr. Takashi Shirahata Prof. Dr. Yasuhiro Mazaki Prof. Dr. Yohji Misaki 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(19):4984-4991
[5]Radialene with quintuple 4,5-benzo-1,3-dithiol-2-ylidenes (DTs) easily forms a stable polycationic salt ( 1 )4+(BF4−)4 owing to its aromatic character in the central cyclopentadienide ring. In this work, it was found that the polycationic salt ( 1 )4+ underwent a hydration reaction in moist polar solvent to give several unexpected products, namely, an oxygen adduct dicationic salt ( 2 )2+, a tetrathiafulvalene (TTF) vinylogue ( 3 ) with 1,4-dithiine-2(3H)-one moieties, and an oxygen adduct of π-extended TTF with a cyclopentenone core ( 4 ). Their molecular structures were fully determined by X-ray crystal-structure analysis. In this reaction, irreversible hydration to the polycationic salt might either initiate the ring expansion and lead to the successive hydration at the specific cationic DT ring (for 3 ), or promote the transannular reactions to the next DT ring followed by elimination of the DT ring (for 4 ). Cyclic voltammetry and differential pulse voltammetry measurements for compound 3 indicated the occurrence of multi redox process resulting from electronic delocalization on the vinylogous TTF moiety. The electronic structures of the cationic species of 3 were also investigated by electronic spectra. 相似文献
44.
Dr. Keishiro Tahara Nazuna Terashita Dr. Ken Tokunaga Shiomi Yabumoto Prof. Jun-ichi Kikuchi Dr. Yoshiki Ozawa Prof. Masaaki Abe 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(60):13728-13738
Realization of molecular quantum cellular automata (QCA), a promising architecture for molecular computing through current-free processes, requires improved understanding and application of mixed-valence (MV) molecules. In this report, we present an electrostatic approach to creating MV subspecies through internalizing opposite charges in close proximity to MV ionic moieties. This approach is demonstrated by unsymmetrically attaching a charge-responsive boron substituent to a well-known organometallic MV complex, biferrocenium. Guest anions (CN− and F−) bind to the Lewis acidic boron center, leading to unusual blue-shifts of the intervalence charge-transfer (IVCT) bands. To the best of our knowledge, this is the first reported example of a zwitterionic MV series in which the degree of positive charge delocalization can be varied by changing the bound anions, and serves to clarify the interplay between IVCT parameters. The key underlying factor is the variable zero-level energy difference in the MV states. This work provides new insight into imbuing MV molecules with external charge-responsiveness, a prerequisite of molecular QCA techniques. 相似文献
45.
Prof. Hidemitsu Uno Kota Muramatsu Shogo Hiraoka Hiroyuki Tahara Mako Hirose Eidai Tamura Tatsumi Shiraishi Dr. John Mack Prof. Nagao Kobayashi Dr. Shigeki Mori Dr. Tetsuo Okujima Dr. Masayoshi Takase 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(25):5701-5708
A bicyclo[2.2.2]octadiene(BCOD)-fused bis(dipyrromethane) derivative was reacted with methylal in the presence of trifluoroacetic acid followed by oxidation with chloranil to give a doubly N-confused phlorin derivative, which did not undergo the retro-Diels–Alder reaction extruding an ethylene molecule on heating. In contrast, a 7-tert-butoxybicyclo[2.2.1]heptadiene(7-BuOBCHD)-fused bis(dipyrromethane) yielded benzene-ring-fused doubly N-confused porphyrins by following similar reaction sequences. 相似文献
46.
Takuma Tahara Dr. Shuichi Suzuki Prof. Dr. Masatoshi Kozaki Prof. Dr. Daisuke Shiomi Dr. Kenji Sugisaki Prof. Dr. Kazunobu Sato Prof. Dr. Takeji Takui Yota Miyake Prof. Dr. Yuko Hosokoshi Prof. Dr. Hiroyuki Nojiri Prof. Dr. Keiji Okada 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(29):7201-7209
The spin–spin and magnetic properties of two (nitronyl nitroxide)-(di-p-anisylamine-phenothiazine) diradical cation salts, ( DAA-PTZ ) + -NN⋅ MBr4− (M=Ga, Fe), have been investigated. These diradical-cation species were prepared by the cross-coupling of iodophenothiazine DAA-PTZ-I with NN-AuPPh3 followed by oxidation with the thianthrenium radical cation ( TA+⋅ MBr4−). These salts were found to be highly stable under aerobic conditions. For the GaBr4 salt, large ferromagnetic intramolecular and small antiferromagnetic intermolecular interactions (J1/kB=+320 K and J2/kB=−2 K, respectively) were observed. The magnetic property of the Fe3+ salt was analyzed by using a six-spin model assuming identical intramolecular exchange interaction (J3/kB=+320 K) and the other exchange interactions (J4/kB=−7 K and J5/kB=−4 K). A significant color change was observed in the UV/Vis/NIR absorption spectra upon electrochemical oxidation of the doublet DAA-PTZ-NN to the triplet ( DAA-PTZ ) + -NN . 相似文献
47.
Katsuhiko Tahara Eiji Nagahara Yasushi Itoi Satoru Nishiyama Shigeru Tsuruya Mitsuo Masai 《Reaction Kinetics and Catalysis Letters》1996,59(1):15-18
The conversion of a carboxylic acid was increased to 90% with 100% selectivity to the corresponding alcohol by calcination of the catalyst precursor, Sn/alumina, of Ru–Sn/alumina in the hydrogenation of the carboxylic acid. 相似文献
48.
Nakamura E Tahara K Matsuo Y Sawamura M 《Journal of the American Chemical Society》2003,125(10):2834-2835
The first hoop-shaped cyclic benzenoid compounds, [10]cyclophenacene derivatives that contain 40 pi electrons, have been synthesized in three or four steps from [60]fullerene by rationally designed chemical modification. The compounds thus synthesized are chemically stable, yellow-colored, luminescent, and EPR-silent. X-ray crystallographic analysis provided high precision structural data sets. On the basis of these results and theoretical investigations, the new cyclic benzenoid molecules were proven to be aromatic. 相似文献
49.
The structure of Bi5Nb3O15 was investigated by refinement of the powder neutron diffraction pattern as well as by structural change through acid treatment and subsequent treatments of an acid-treated product with n-alkylamines. Rietveld refinement suggests that Bi5Nb3O15 adopts a mixed-layer Aurivillius-related phase structure, [Bi2O2]+[NbO4]+[Bi2O2]+[BiNb2O7] [Pnc2 (space group No. 30)] with a=2.1011(4), b=0.5473(1) and c=0.5463(1) nm. After the acid treatment of Bi5Nb3O15 with 3 mol/L HCl, a new reflection (at 2.25 nm after drying at room temperature or at 1.89 nm after drying at 120 °C) appeared in the X-ray diffraction (XRD) pattern in addition to the reflections due to Bi5Nb3O15. Upon acid treatment, a part of the Bi ions were lost and essentially no Nb ions were dissolved during acid treatment to give a Bi/Nb molar ratio of 1.4. The TG curves of the acid-treated product showed mass loss (ca. 4 mass%) in the range of 300-600 °C. It was also demonstrated that the particle shapes did not change upon acid treatment. The reaction of the acid-treated product (after drying at room temperature) with n-alkylamines led to a shift of the newly appearing reflection to a lower angle, and the d-value of the low-angle reflection increased linearly in accordance with the increment of the number of carbon atoms in n-alkylamines. These results indicate that the [Bi2O2] sheet in Bi5Nb3O15 was partially leached by acid treatment to form a layered compound H4BiNb3O11·xH2O, capable of accommodating n-alkylamines in the interlayer space, and its anhydrous form, H4BiNb3O11, upon drying. Based on the variation in the interlayer distance upon intercalation of n-alkylamines into the acid-treated product, the structure of the acid-treated product can be suggested to comprise alternately stacked protonated [BiNb2O7] and [NbO4] sheets, a result consistent with the Rietveld refinement of Bi5Nb3O15. 相似文献
50.
Introducing fine polymeric filaments as the extraction medium, a miniaturized sample preparation technique for micro-column liquid chromatography (micro-LC) has been developed along with the investigation of a reproducible preparation scheme of the extraction capillary. The polymeric filaments were packed longitudinally into either a fused-silica capillary or a polyether ether ketone (PEEK) capillary of appropriate dimensions, and the extraction capillary was installed to the injection valve in micro-LC system. The number of packed filaments should be precisely counted before the packing process to make sure the reproducible preparation of the extraction capillary. With conventional stationary phase materials for open-tubular gas chromatography, polymeric coating to the surface of the filaments was also studied in order to further enhance the extraction performance and selectivity. Coated with the polymeric material suitable for the extraction of particular analyte, a dramatic improvement on the extraction power was obtained. The results suggest that the future possibility of novel tailored fibrous extraction medium with an appropriate coating on it, especially for the analysis of complex sample matrices. 相似文献