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321.
Toshinori Miyagi Sho Okada Naoya Tada Masahiro Sugihara Natsuko Kagawa Tetsuhiko Takabatake Masahiro Toyota 《Tetrahedron letters》2019,60(25):1653-1657
A Pd-catalyzed orthogonal synthesis of substituted 2-hydroxybenzoates and substituted cyclohexanones was developed for the first time. The substituted 2-hydroxybenzoates were obtained from acyclic unsaturated 1,3-carbonyl compounds using a combination of catalytic Pd(OAc)2 and Cu(OAc)2. On the other hand, the substituted cyclohexanones were produced from similar substrates via catalytic Pd(OAc)2 and hydrogen chloride. Each transformation was clean, easy to work up, provided the desired compounds in good purities, and did not require column chromatography purification. 相似文献
322.
Ryouta Kawanishi Lacksany Phongphane Prof. Seiji Iwasa Prof. Kazutaka Shibatomi 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(31):7453-7456
Syntheses of substituted pyridines and fluorinated compounds, which are often pharmaceutical targets, are important objectives in organic chemistry. Herein, we found that decarboxylative fluorination of lithium 2-pyridylacetates occur under catalyst-free conditions. The phenomenon can be applied to one-pot transformation of substituted methyl 2-pyridylacetate to 2-(fluoroalkyl)pyridine by decarboxylative fluorination of the intermediate lithium 2-pyridylacetate. This method was also applied to the syntheses of 2-(difluoroalkyl)pyridines. 相似文献
323.
Dr. Toyoto Sato Dr. Luke L. Daemen Dr. Yongqiang Cheng Dr. Anibal J. Ramirez-Cuesta Dr. Kazutaka Ikeda Takuma Aoki Dr. Toshiya Otomo Prof. Shin-ichi Orimo 《Chemphyschem》2019,20(10):1392-1397
The hydrogen-release reaction of a complex transition metal hydride, LaMg2NiH7, composed of La3+, 2×Mg2+, [NiH4]4− and 3×H−, was studied by thermal analyses, powder X-ray, and neutron diffraction and inelastic neutron scattering. Upon heating, LaMg2NiH7 released hydrogen at approximately 567 K and decomposed into LaH2−3 and Mg2Ni. Before the reaction, covalently bound hydrogen (Hc°v.) in [NiH4]4− exhibited a larger atomic displacement than H−, although a weakening of the chemical bonds around [NiH4]4− and H− was observed. These results indicate the precursor phenomenon of a hydrogen-release reaction, wherein there is a large atomic displacement of Hc°v. that induces the hydrogen-release reaction rather than H−. As an isothermal reaction, LaMg2NiH7 formed LaMg2NiH2.4 at 503 K in vacuum for 48 h, and LaMg2NiH2.4 reacted with hydrogen to reform LaMg2NiH7 at 473 K under 1 MPa of H2 gas pressure for 10 h. These results revealed that LaMg2NiH7 exhibited partially reversible hydrogen-release and uptake reactions. 相似文献
324.
Matthias Schnitzlein Dr. Chongwei Zhu Dr. Kazutaka Shoyama Prof. Dr. Frank Würthner 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(61):e202202053
Palladium-catalyzed [5+2] annulation of 1-boraphenalenes with ortho-dihaloarenes afforded negatively curved π-extended pleiadienes. Two benzo[1,2-i:4,5-i’]dipleiadienes (BDPs) featuring a seven-six-seven-membered ring arrangement were synthesized and investigated. Their crystal structure revealed a unique packing arrangement and theoretical calculations were employed to shed light onto the dynamic behavior of the BDP moiety and its aromaticity. Further, a naphthalene-fused pleiadiene was stitched together by oxidative cyclodehydrogenation to yield an additional five-membered ring. This formal azulene moiety led to distinct changes in optical and redox properties and increased perturbation of the aromatic system. 相似文献
325.
Dr. Kenji Sugisaki Dr. Kazuo Toyota Prof. Dr. Kazunobu Sato Prof. Dr. Daisuke Shiomi Prof. Dr. Masahiro Kitagawa Prof. Dr. Takeji Takui 《Chemphyschem》2010,11(14):3146-3151
Zero‐field splitting (ZFS) tensors ( D tensors) of organic high‐spin oligonitrenes/oligocarbenes up to spin‐septet are quantitatively determined on the basis of quantum chemical calculations. The spin–orbit contributions, D SO tensors are calculated in terms of a hybrid CASSCF/MRMP2 approach, which was recently proposed by us. The spin–spin counterparts, D SS tensors are computed based on McWeeny–Mizuno’s equation in conjunction with the RODFT spin densities. The present calculations show that more than 10 % of ZFS arises from spin–orbit interactions in the high‐spin nitrenes under study. Contributions of spin‐bearing site–site interactions are estimated with the aid of a semi‐empirical model for the D tensors and found to be ca. 5 % of the D SO tensor. The analysis of intermediate states reveal that the largest contributions to the calculated D SO tensors are attributed to intra‐site spin flip excitations and delocalized π and π* orbitals play an important role in the inter‐site spin–orbit interactions. 相似文献
326.
Treatment of (NH4)[Au(D‐Hpen‐S)2](D‐H2pen = D‐penicillamine) with CoCl2·6H2O in an acetate buffer solution, followed by air oxidation, gave neutral AuICoIII and anionic AuI3CoIII2 polynuclear complexes, [Au3Co3(D‐pen‐N,O,S)6]([ 1 ]) and [Au3Co2(D‐pen‐N,S)6]3? ([ 2 ]3?), which were separated by anion‐exchange column chromatography. Complexes [ 1 ] and [ 2 ]3? each formed a single isomer, and their structures were determined by single‐crystal X‐ray crystallography. In [ 1 ], each of three [Au(D‐pen‐S)2]3?metalloligands coordinates to two CoIII ions in a bis‐tridentate‐N,O,S mode to form a cyclic AuI3CoIII3 hexanuclear structure, in which three [Co(D‐pen‐N,O,S)2]? octahedral units and six bridging S atoms adopt trans(O) geometrical and R chiral configurations, respectively. In [ 2 ]3?, each of three [Au(D‐pen‐S)2]3? metalloligands coordinates to two CoIII ions in a bis‐bidentate‐N,S mode to form a AuI3CoIII2 pentanuclear structure, in which two [Co(D‐pen‐N,S)3]3? units and six bridging S atoms adopt ∧ and R chiral configurations, respectively. 相似文献
327.
Ryuji Nakao Takehito Ito Kazutaka Hayashi Toshimitsu Fukumura Kazutoshi Suzuki 《Journal of chromatography. A》2009,1216(18):3933-3940
A rapid and efficient preparative high-performance liquid chromatographic procedure was established to purify short-lived positron emission tomography radio-probes. This method is based on hydrophilic interaction chromatography utilizing a semi-preparative silica column (10 mm I.D.) and a high volatile organic mobile phase (>90% acetonitrile). In nine different radiopharmaceuticals studied, six compounds could be separated from the unlabeled precursor with good resolution and faster elution than its precursor. These characteristics enabled significant shortening of the separation and evaporation processes in the manufacture of short-lived radiopharmaceuticals. Several 11C-radiopharmaceuticals could be prepared within one half-life of carbon-11 (20.4 min), including radiosynthesis, purification and formulation steps with sufficient radiochemical/chemical purity and high levels of radioactivity/specific radioactivity. 相似文献
328.
Teruaki Koto Kenji Sugisaki Kazunobu Sato Daisuke Shiomi Kazuo Toyota Koichi Itoh Edel Wasserman Paul M. Lahti Takeji Takui 《Applied magnetic resonance》2010,37(1-4):703-736
In high-spin chemistry, random-orientation fine-structure electron paramagnetic resonance (FS ESR) spectroscopy holds the advantages of the most facile and convenient method to identify high-spin systems. The FS ESR spectroscopy for high spins in frozen rigid glasses has seemingly been well established since the first spin-quintet m-dicarbene and m-dinitrene appeared in 1967. The FS ESR spectra of organic quintet entities generated by photolysis in the 2-methyltetrahydrofuran (2-MTHF) glass, however, have never been fully analyzed due to a peculiar line broadening appearing at many canonical peaks. The line broadening has been a notorious obstacle that masks key FS transitions of many cases in organic glasses or argon matrices. We examine the origin of the line broadening, illustrating the comprehensive spectral analysis for m-dinitrenes and other types of typical quintet-state dinitrenes observed in the 2-MTHF glass. Our new approach to the line broadening analysis invokes both exact analytical solutions for the resonance fields of canonical peaks and a magnetic-parameter gradient method. We have derived the exact analytical expressions for FS canonical peaks for high-spin states, for the first time. A microscopic origin of the line broadening observed for high-spin nitrenes generated by photolysis in rigid glasses is proposed on the basis of quantum chemical calculations of the D-tensor. 相似文献
329.
In this paper we consider the minimizing sequence for some energy functional of an elliptic equation associated with the mean field limit of the point vortex distribution one-sided Borel probability measure. If such a sequence blows up, we derive some estimate which is related to the behavior of solution near the blow-up point. Moreover, we study the two-intensities case to consider the sufficient condition for this estimate. Our main results are new for the standard mean field equation as well. 相似文献
330.
Rational Molecular Design and Synthesis of Highly Thermo‐ and Photostable Near‐Infrared‐Absorbing Heptamethine Cyanine Dyes with the Use of Fluorine Atoms 下载免费PDF全文
Prof. Dr. Kazumasa Funabiki Kazutaka Yagi Masato Ueta Mitsuru Nakajima Masako Horiuchi Dr. Yasuhiro Kubota Prof. Dr. Masaki Mastui 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(35):12282-12285
Highly thermo‐ and photostable, near‐infrared‐absorbing heptamethine cyanine dyes were achieved with the use of fluorine‐containing components. In particular, one prepared heptamethine cyanine dye, bearing a tetrakis(pentafluorophenyl)borate as a counter anion and an N‐ethyl‐2,2,2‐trifluoroacetamido group at the meso position, showed not only a high decomposition temperature (Tdt), but also very high photostability toward white LED irradiation. 相似文献