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351.
Synthesis of Phosphabenzenes by an Iron‐Catalyzed [2+2+2] Cycloaddition Reaction of Diynes with Phosphaalkynes
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Dr. Kazunari Nakajima Shohei Takata Prof. Dr. Ken Sakata Prof. Dr. Yoshiaki Nishibayashi 《Angewandte Chemie (International ed. in English)》2015,54(26):7597-7601
A method for the synthesis of phosphabenzenes under iron catalysis is described. Thus, the FeI2‐catalyzed [2+2+2] cycloaddition of diynes with phosphaalkynes in m‐xylene gave a variety of phosphabenzenes in good to high yields (up to 87 % yield). 相似文献
352.
Efficient Visible‐Light‐Driven Z‐Scheme Overall Water Splitting Using a MgTa2O6−xNy /TaON Heterostructure Photocatalyst for H2 Evolution
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Shanshan Chen Yu Qi Dr. Takashi Hisatomi Qian Ding Tomohiro Asai Zheng Li Dr. Su Su Khine Ma Prof. Fuxiang Zhang Prof. Kazunari Domen Prof. Can Li 《Angewandte Chemie (International ed. in English)》2015,54(29):8498-8501
An (oxy)nitride‐based heterostructure for powdered Z‐scheme overall water splitting is presented. Compared with the single MgTa2O6?xNy or TaON photocatalyst, a MgTa2O6?xNy /TaON heterostructure fabricated by a simple one‐pot nitridation route was demonstrated to effectively suppress the recombination of carriers by efficient spatial charge separation and decreased defect density. By employing Pt‐loaded MgTa2O6?xNy /TaON as a H2‐evolving photocatalyst, a Z‐scheme overall water splitting system with an apparent quantum efficiency (AQE) of 6.8 % at 420 nm was constructed (PtOx‐WO3 and IO3?/I? pairs were used as an O2‐evolving photocatalyst and a redox mediator, respectively), the activity of which is circa 7 or 360 times of that using Pt‐TaON or Pt‐MgTa2O6?xNy as a H2‐evolving photocatalyst, respectively. To the best of our knowledge, this is the highest AQE among the powdered Z‐scheme overall water splitting systems ever reported. 相似文献
353.
Shogo Kuriyama Kazuya Arashiba Kazunari Nakajima Hiromasa Tanaka Kazunari Yoshizawa Yoshiaki Nishibayashi 《Chemical science》2015,6(7):3940-3951
A series of dinitrogen-bridged dimolybdenum–dinitrogen complexes bearing metallocene-substituted PNP-pincer ligands is synthesized by the reduction of the corresponding monomeric molybdenum–trichloride complexes under 1 atm of molecular dinitrogen. Introduction of ferrocene as a redox-active moiety to the pyridine ring of the PNP-pincer ligand increases the catalytic activity for the formation of ammonia from molecular dinitrogen, up to 45 equiv. of ammonia being formed based on the catalyst (22 equiv. of ammonia based on each molybdenum atom of the catalyst). The time profile for the catalytic reaction reveals that the presence of the ferrocene unit in the catalyst increases the rate of ammonia formation. Electrochemical measurement and theoretical studies indicate that an interaction between the Fe atom of the ferrocene moiety and the Mo atom in the catalyst may play an important role to achieve a high catalytic activity. 相似文献
354.
Shigeru Deguchi Kazunari Akiyoshi Bjrn Lindman Junzo Sunamoto 《Macromolecular Symposia》1996,109(1):1-14
Solution properties of an aqueous mixture of cholesterol-bearing pullulan (CHP) and an ionic surfactant, sodium dodecyl sulfate (SDS) or dodecyltrimethylammonium chloride (DoTAC), were studied. The mixture forms gel or sol depending on the polymer-surfactant composition. Because the unmodified pullulan/surfactant/water mixture does not show any gel formation at all over the composition range studied, the hydrophobic cholesterol moieties play an essential and important role in the gel formation. The phase behavior could be interpreted by formation of mixed micelles between cholesterol moieties of CHP and the surfactants. This was supported also by SAXS studies in the sol region. Rheological measurements of the gel showed that viscoelastic response of the CHP/SDS gel was controlled by at least two different processes with shorter and longer relaxation times. This was different from previously reported results for a system such as hydrophobically modified (hydroxyethyl)cellulose (HMHEC) and SDS. 相似文献
355.
Shun‐ichi Kawahara Chojiro Kojima Kazunari Taira Tadafumi Uchimaru 《Helvetica chimica acta》2003,86(10):3265-3273
trans‐Hydrogen‐bond hyperfine splitting via magnetic interaction, which is observed as J‐coupling in NMR experiments, was theoretically studied. trans‐Hydrogen‐bond hyperfine splitting should be closely related to the orbital interaction between the lone‐pair orbital of the H‐bond acceptor and the antibond orbital of the H‐bond donor. A linear relationship was observed between magnetic interaction hyperfine splitting through a H‐bond and the H‐bond strength. The relationship was dependent on the type of the nucleus forming the H‐bond; linear correlation was observed in N H⋅⋅⋅O/N type or O H⋅⋅⋅N type H‐bonded complexes, but not in O H⋅⋅⋅O type H‐bonded complexes. 相似文献
356.
357.
358.
Dr. Takayuki Iwata Satoru Kumagai Dr. Tatsuro Yoshinaga Masato Hanada Prof. Dr. Yoshihito Shiota Prof. Dr. Kazunari Yoshizawa Prof. Dr. Mitsuru Shindo 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(45):11548-11553
A Pd-catalyzed domino reaction of 1,8,13-tribromo-9-methoxytriptycenes is reported. Under conventional Suzuki coupling conditions, the triptycenes underwent multiple transformations to give 1,9-bridged triptycenes. Based on mechanistic investigations, a single Pd catalyst functions as Pd0, PdII and PdIV species to catalyze four distinct processes: (1) aryl to alkyl 1,5-Pd migration, (2) intramolecular arylation, (3) homocoupling of phenylboronic acid and (4) Suzuki coupling. DFT calculations revealed that 1,5-Pd migration likely proceeds via both concerted PdII and stepwise PdIV routes. Asymmetric synthesis of the chiral triptycenes, as well as optical resolution, and further transformation are also reported. 相似文献
359.
N. Nogawa S. Momose K. Miyazawa Y. Makide K. Oohashi K. Hashimoto N. Morikawa 《Journal of Radioanalytical and Nuclear Chemistry》1999,239(2):385-389
Optimum conditions were determined for high-yield synthesis of186Re- and188Re-meso-2, 3-dimercaptosuccinic acid complexes applicable to animal injection. The yield was more than 95% under the conditions
used. The bone accumulation of the complexes was remarkable in the biodistributions in mice. 相似文献
360.
Kazunari Naka Hirofumi Sato Akihiro Morita Fumio Hirata Shigeki Kato 《Theoretical chemistry accounts》1999,102(1-6):165-169
The free-energy profile for the Menshutkin-type reaction NH3 + CH3Cl → NH3CH3
+ + Cl− in aqueous solution is studied using the RISM-SCF method. The effect of electron correlation on the free-energy profile is
estimated by the RISM-MP2 method at the HF optimized geometries along the reaction coordinate. Solvation was found to have
a large influence on the vibrational frequencies at the reactant, transition state and product; these vibrational frequencies
are utilized to calculate the zero-point energy correction of the free-energy profile. The computed barrier height and reaction
exothermicity are in reasonable agreement with those of experiment and previous calculations. The change of solvation structure
along the reaction path is represented by radial distribution functions between solute-solvent atomic sites. The mechanisms
of the reaction are discussed from the view points of solute electronic and solvation structures.
Received: 26 June 1998/Accepted: 28 August 1998 / Published online: 2 November 1998 相似文献