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1.
Controllable Electronic Structures and Photoinduced Processes of Bay‐Linked Perylenediimide Dimers and a Ferrocene‐Linked Triad 下载免费PDF全文
Haruki Horinouchi Dr. Hayato Sakai Prof. Yasuyuki Araki Prof. Tomo Sakanoue Prof. Taishi Takenobu Prof. Takehiko Wada Prof. Nikolai V. Tkachenko Prof. Taku Hasobe 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(28):9631-9641
A series of perylene‐3,4,9,10‐bis(dicarboximide) (PDI) dimers linked through the bay regions was systematically synthesized to examine the electronic structures and photophysical properties in dependence on the distance and orientation between the two PDI units. The spectroscopic and electrochemical measurements suggested that the coupling value of a directly linked PDI dimer (PDI)2 is much larger than those of para‐ and meta‐phenylene‐bridged PDI dimers p‐(PDI)2 and m‐(PDI)2. The width of Davydov splitting was quantitatively evaluated to compare the coupling values between the two PDI units in these dimers by absorption spectroscopy in frozen 2‐methyl‐THF. Excimer formation of PDI dimers induced the strong fluorescence quenching and large red‐shifts. Femtosecond transient absorption revealed a broad absorption derived from an excimer in the range from about 600 nm to the near‐IR region. The rate constants of formation and decay of the excimer are strongly dependent on the coupling values. Time‐resolved measurements on ferrocene‐linked p‐(PDI)2 revealed a competition between the photoinduced processes of electron transfer and excimer formation in PhCN, which is in sharp contrast with the sole electron‐transfer process in toluene. 相似文献
2.
Dr. Yasuyuki Yamada Hayato Iida Shinya Shibano Dr. Nozomi Mihara Prof. Tatsuhisa Kato Prof. Kentaro Tanaka 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(37):e202200819
Spatial distance is an important factor in controlling the functional interactions between molecular units in a conjugate; therefore, the bridging unit has been closely examined. Here, we examined the effect of the flexibility of bridging alkyl chains on the proximity of stacked porphyrin and phthalocyanine conjugated with a fourfold rotaxane linkage. We found that closely stacking two π systems requires bridging alkyl chains above a certain length, and the shorter bridges hinder stacking because of their lower flexibility. The stacking distance between porphyrin and phthalocyanine in the conjugate with decyl (C10) chains was estimated to be 4.03 Å and showed a unique physical character arising from short-distance interactions. The longer alkyl chains minimized steric restriction inside the fourfold rotaxane and allowed efficient communication between the porphyrin and phthalocyanine units. This is due to the flexibility of the side chains. 相似文献
3.
Coronenetetraimide‐Centered Cruciform Pentamers Containing Multiporphyrin Units: Synthesis and Sequential Photoinduced Energy‐ and Electron‐Transfer Dynamics 下载免费PDF全文
Prof. Taku Hasobe Koichi Ida Dr. Hayato Sakai Prof. Kei Ohkubo Prof. Shunichi Fukuzumi 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(31):11196-11205
A series of coronenetetraimide (CorTIm)‐centered cruciform pentamers containing multiporphyrin units, in which four porphyrin units are covalently linked to a CorTIm core through benzyl linkages, were designed and synthesized to investigate their structural, spectroscopic, and electrochemical properties as well as photoinduced electron‐ and energy‐transfer dynamics. These systems afforded the first synthetic case of coroneneimide derivatives covalently linked with dye molecules. The steady‐state absorption and electrochemical results indicate that a CorTIm and four porphyrin units were successfully characterized by the corresponding reference monomers. In contrast, the steady‐state fluorescence measurements demonstrated that strong fluorescence quenching relative to the corresponding monomer units was observed in these pentamers. Nanosecond laser flash photolysis measurements revealed the occurrence of intermolecular electron transfer from triplet excited state of zinc porphyrins to CorTIm. Femtosecond laser‐induced transient absorption measurements for excitation of the CorTIm unit clearly demonstrate the sequential photoinduced energy and electron transfer between CorTIm and porphyrins, that is, occurrence of the initial energy transfer from CorTIm (energy donor) to porphyrins (energy acceptor) and subsequent electron transfer from porphyrins (electron donor) to CorTIm (electron acceptor) in these pentamers, whereas only the electron‐transfer process from porphyrins to CorTIm was observed when we mainly excite porphyrin units. Finally, construction of high‐order supramolecular patterning of these pentamers was performed by utilizing self‐assembly and physical dewetting during the evaporation of solvent. 相似文献
4.
Dr. Masahito Yoshida Yoshitaka Ishida Kenta Adachi Hayato Murase Dr. Hiroshi Nakagawa Prof.Dr. Takayuki Doi 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(50):18417-18430
The solid‐phase combinatorial synthesis of cyclodepsipeptide destruxin E has been demonstrated. The combinatorial synthesis of cyclization precursors 8 was achieved by using a split and pool method on SynPhase Lanterns. The products were successfully macrolactonized in parallel in the solution phase by using 2‐methyl‐6‐nitrobenzoic anhydride and 4‐(dimethylamino)pyridine N‐oxide to afford macrolactones 9 , and the subsequent formation of an epoxide in the side chain gave 18 member destruxin E analogues 6 . Biological evaluation of analogues 6 indicated that the N‐MeAla residue was crucial to the induction of morphological changes in osteoclast‐like multinuclear cells (OCLs). Based on structure–activity relationships, azido‐containing analogues 15 were then designed for use as a molecular probe. The synthesis and biological evaluation of analogues 15 revealed that 15 b , in which the Ile residue was replaced with a Lys(N3) residue, induced morphological changes in OCLs at a sufficient concentration, and modification around the Ile residue would be tolerated for attachment of a chemical tag toward the target identification of destruxin E ( 1 ). 相似文献
5.
Salt‐Free Reduction of Nonprecious Transition‐Metal Compounds: Generation of Amorphous Ni Nanoparticles for Catalytic C–C Bond Formation 下载免费PDF全文
Dr. Taiga Yurino Yohei Ueda Dr. Yoshiki Shimizu Dr. Shinji Tanaka Haruka Nishiyama Prof. Dr. Hayato Tsurugi Prof. Dr. Kazuhiko Sato Prof. Dr. Kazushi Mashima 《Angewandte Chemie (International ed. in English)》2015,54(48):14437-14441
A salt‐free procedure for the generation of a wide variety of metal(0) particles, including Fe, Co, Ni, and Cu, was achieved using 2,3,5,6‐tetramethyl‐1,4‐bis(trimethylsilyl)‐1,4‐diaza‐2,5‐cyclohexadiene ( 1 ), which reduced the corresponding metal precursors under mild conditions. Notably, Ni particles formed in situ from the treatment of Ni(acac)2 (acac=acetylacetonate) with 1 in toluene exhibited significant catalytic activity for reductive C? C bond‐forming reactions of aryl halides in the presence of excess amounts of 1 . By examination of high‐magnification transmission electron microscopy images and electron diffraction patterns, we concluded that amorphous Ni nanoparticles (Ni aNPs) were essential for the high catalytic activity. 相似文献
6.
Peter J. Cumpson Naoko Sano Ian W. Fletcher Jose F. Portoles Mariela Bravo‐Sanchez Anders J. Barlow 《Surface and interface analysis : SIA》2015,47(10):986-993
Principal component analysis (PCA) and other multivariate analysis methods have been used increasingly to analyse and understand depth profiles in X‐ray photoelectron spectroscopy (XPS), Auger electron spectroscopy (AES) and secondary ion mass spectrometry (SIMS). These methods have proved equally useful in fundamental studies as in applied work where speed of interpretation is very valuable. Until now these methods have been difficult to apply to very large datasets such as spectra associated with 2D images or 3D depth‐profiles. Existing algorithms for computing PCA matrices have been either too slow or demanded more memory than is available on desktop PCs. This often forces analysts to ‘bin’ spectra on much more coarse a grid than they would like, perhaps even to unity mass bins even though much higher resolution is available, or select only part of an image for PCA analysis, even though PCA of the full data would be preferred. We apply the new ‘random vectors’ method of singular value decomposition proposed by Halko and co‐authors to time‐of‐flight (ToF)SIMS data for the first time. This increases the speed of calculation by a factor of several hundred, making PCA of these datasets practical on desktop PCs for the first time. For large images or 3D depth profiles we have implemented a version of this algorithm which minimises memory needs, so that even datasets too large to store in memory can be processed into PCA results on an ordinary PC with a few gigabytes of memory in a few hours. We present results from ToFSIMS imaging of a citrate crystal and a basalt rock sample, the largest of which is 134GB in file size corresponding to 67 111 mass values at each of 512 × 512 pixels. This was processed into 100 PCA components in six hours on a conventional Windows desktop PC. © 2015 The Authors. Surface and Interface Analysis published by John Wiley & Sons Ltd. 相似文献
7.
Yu Shibata Haruki Nagae Shiki Sumiya Rapha?l Rochat Hayato Tsurugi Kazushi Mashima 《Chemical science》2015,6(10):5394-5399
An alkylyttrium complex supported by an N,N′-bis(2,6-diisopropylphenyl)ethylenediamido ligand, (ArNCH2CH2NAr)Y(CH2SiMe3)(THF)2 (1, Ar = 2,6-iPr2C6H3), activated an ortho-phenyl C–H bond of 2-phenylpyridine (2a) to form a (2-pyridylphenyl)yttrium complex (3a) containing a five-membered metallacycle. Subsequently, a unique C(sp2)–C(sp2) coupling of 2-phenylpyridine proceeded through a bimetallic yttrium intermediate, derived from an intramolecular shift of the yttrium center to an ortho-position of the pyridine ring in 3a, to yield a bimetallic yttrium complex (4a) bridged by two-electron reduced 6,6′-diphenyl-2,2′-bipyridyl. Aryl substituents at the ortho-position of the pyridine ring were key in order to destabilize the μ,κ2-(C,N)-pyridyldiyttrium intermediate prior to the C(sp2)–C(sp2) bond formation. 相似文献
8.
9.
Yuta Goto Yu Miyagi Natsuhiro Sano Fumio Sanda 《Journal of polymer science. Part A, Polymer chemistry》2017,55(18):3011-3016
Chloro- and aryl-substituted acetylene monomers having an optically active group were polymerized by a Pd catalyst [(tBu3P)PdMeCl] bearing a bulky phosphine ligand, and by MoCl5 for comparison. The corresponding disubstituted acetylene polymers with Mn's = 2000–19,500 and 6900–10,800 were obtained in 29–83% and 11–62% yields when the Pd and Mo catalysts were used, respectively. The formation of polyacetylenes, poly[(R)- 1p ], poly[(R)- 1m ], and poly[(S)- 2p ] were confirmed by SEC and the presence of a Raman scattering peak based on the alternating double bonds of the main chain. Pd-based poly[(R)- 1m ] exhibited CD signals around 350 nm assignable to a certain secondary structure, while Mo-based poly[(R)- 1m ] did not. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55, 3011–3016 相似文献
10.
A new effective copper catalyzed CO coupling reaction using excess amount of strongly coordinating monodentate ligands was successfully developed. Among the DMAP-type monodentate ligands, 4-pyrrolidinopyridine afforded the best results. The developed reaction is widely applicable for the synthesis of various hindered or acyclic secondary alkyl-aryl ethers. In this study, a novel and remarkable acceleration of the coupling reaction using excess amount of monodentate ligands was discovered. 相似文献