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951.
Dr. Satoru Arimitsu 《Chemical record (New York, N.Y.)》2023,23(9):e202300021
This account presents the synthesis and application of propargylic and allylic fluorides containing hydroxy or carbonyl functional groups. In particular, the Barbier-type reaction of difluoropropargyl bromides with aldehydes or chloroformates provides versatile propargylic fluorides, and the organocatalytic fluorination of dienamine intermediates has been demonstrated as an effective method to obtain allylic fluorides stereoselectively. Additionally, mechanistic insights into such reactions are discussed with the aid of density functional theory calculations. The report also describes the preparation of fluorinated 1,7-diyne or 1,7-enyne derivatives of these compounds. These propargylic and allylic fluorides can be used as building blocks for fluorinated heterocycles, such as fluorinated furans, tetrahydrofurans, and lactams. Additionally, fluorinated bi- or tri-heterocyclic compounds can be synthesized via transition-metal-catalyzed reactions with fluorinated 1,7-diyne or 1,7-enyne derivatives. 相似文献
952.
Effect of reactive oxygen species generated with ultraviolet lamp and plasma on polyimide surface modification 下载免费PDF全文
Takahiro Kondo Ryota Watanabe Yuta Shimoyama Kazuho Shinohe Sergei A. Kulinich Satoru Iwamori 《Surface and interface analysis : SIA》2017,49(11):1069-1077
Understanding the effect of reactive oxygen species (ROS), such as singlet oxygen molecule and atomic oxygen, on polyimide (PI) film properties, such as wettability, morphology, and chemical bonding state, is essential for further development of PI‐based surfaces. We investigated the effect of different ROS generated during ultraviolet (UV) and plasma treatment in oxygen gas on surface modification of Kapton PI. Different surface modification techniques, UV and plasma treatment, are known to generate different ROS. In this work, we demonstrate the effect of different ROS on PI surface modification. From the diagnostics of ROS by means of electron spin resonance and optical emission spectroscopy, we confirmed that during UV treatment, excited singlet oxygen molecules are the main ROS, while plasma treatment mainly generated atomic oxygen. The wettability of PI surface treated by UV and plasma resulted in hydrophilic PI surfaces. XPS results show that the wettability of PI samples is mainly determined by their surface O/C ratio. However, chemical bonding states were different: while UV treatment tended to generate C=O bonds, while plasma treatment tended to generate both C―O and C=O bonds. Singlet oxygen molecules are concluded to be the main oxidant during UV treatment, and their main reaction with PI was concluded to be of the addition type, leading to an increase of C=O groups on the surface of PI film. Meanwhile, atomic oxygen species were the main oxidant during plasma treatment, reacting with the PI surface through both etching and addition reaction, resulting in a wider variety of bonds, including both C―O and C=O groups. 相似文献
953.
Dr. Yuta Morinaka Dr. Rui Zhang Dr. Satoru Sato Dr. Hidefumi Nikawa Prof. Dr. Tatsuhisa Kato Prof. Dr. Ko Furukawa Prof. Dr. Michio Yamada Prof. Dr. Yutaka Maeda Dr. Michihisa Murata Prof. Dr. Atsushi Wakamiya Prof. Dr. Shigeru Nagase Prof. Dr. Takeshi Akasaka Prof. Dr. Yasujiro Murata 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(23):6588-6591
To investigate the intrinsic reactivity of atomic nitrogen, which had previously been accomplished only by examining its decay in the gas phase using special equipment, a nitrogen atom was inserted into a series of molecule-encapsulating C60 and C70 fullerenes. Among the studied endofullerenes, H2@C70 was able to encapsulate an additional nitrogen atom within the fullerene cage under radiofrequency plasma conditions. The product was analyzed by ESR spectroscopy and mass spectrometry in solution, which revealed that the nitrogen atom with a quartet ground state does not react but weakly interact with the H2 molecule, thus demonstrating the utility of such fullerenes as “nanoflasks”. 相似文献
954.
Tandem trimer pyrrole–imidazole polyamide probes targeting 18 base pairs in human telomere sequences
Yusuke Kawamoto Asuka Sasaki Kaori Hashiya Satoru Ide Toshikazu Bando Kazuhiro Maeshima Hiroshi Sugiyama 《Chemical science》2015,6(4):2307-2312
The binding of molecules to specific DNA sequences is important for imaging genome DNA and for studying gene expression. Increasing the number of base pairs targeted by these molecules would provide greater specificity. N-Methylpyrrole–N-methylimidazole (Py–Im) polyamides are one type of such molecules and can bind to the minor groove of DNA in a sequence-specific manner without causing denaturation of DNA. Our recent work has demonstrated that tandem hairpin Py–Im polyamides conjugated with a fluorescent dye can be synthesized easily and can serve as new probes for studying human telomeres under mild conditions. Herein, to improve their selectivities to telomeres by targeting longer sequences, we designed and synthesized a fluorescent tandem trimer Py–Im polyamide probe, comprising three hairpins and two connecting regions (hinges). The new motif bound to 18 bp dsDNA in human telomeric repeats (TTAGGG)n, the longest sequence for specific binding reported for Py–Im polyamides. We compared the binding affinities and the abilities to discriminate mismatch, the UV-visible absorption and fluorescence spectra, and telomere staining in human cells between the tandem trimer and a previously developed tandem hairpin. We found that the tandem trimer Py–Im polyamide probe has higher ability to recognize telomeric repeats and stains telomeres in chemically fixed cells with lower background signal. 相似文献
955.
956.
B Z Zheng H Maeda M Mori S Kusaka O Yonemitsu T Matsushima N Nakajima J Uenishi 《Chemical & pharmaceutical bulletin》1999,47(9):1288-1296
An efficient and stereoselective synthesis of the C13-C23 part (8) was achieved starting from methyl (R)- and (S)-3-hydroxy-2-methylpropionates (9) via coupling of the C13-C17 aldehyde (6), prepared by Evans asymmetric aldol reaction, with the C18-C21 iodoalkene (5b) by taking advantage of the 3,4-dimethoxybenzyl protecting group. 相似文献
957.
Satoru Yamada Masayoshi Nakano Masamichi Nishino Kizashi Yamaguchi 《Optical Review》1999,6(3):237-241
We study the second hyperpolarizabilities (ɣ) for anion, neutral and cation radicals and find that magnitudes of ɣ (| ɣ |) of the radicals are sensitively influenced by features of each charged state. It is also found that electron-correlation dependence of ɣ could be related to the resonance structure contributing to the ground state of the molecules.This paper was originally presented at the 5th International Conference on NEAR FIELD OPTICS and RELATED TECHNOLOGIES (NFO-5), which was held on December 6–10, 1998 at Coganoi Bay Hotel, Shirahama, Japan, in cooperation with the Japan Society of Applied Physics and Mombusho Grant-in Aid for Scientific Research on Priority Areas “Near-field Nano-optics” Project, sponsored by Japan Society for the Promotion of Science. 相似文献
958.
Takashi Kawakami Toru Saito Sandeep Sharma Shusuke Yamanaka Satoru Yamada Takahito Nakajima 《Molecular physics》2017,115(17-18):2267-2284
ABSTRACTIn this work, we show that the natural orbitals of unrestricted hybrid density functional theory (UHDFT) can be used as the active space orbitals to perform multireference (MR) calculations, for example, the density matrix renormalisation group (DMRG) and Mukherjee-type (Mk) MR coupled-cluster (CC) method. By including a sufficiently large number of these natural orbitals, full-valence (FV) active space can be identified without recourse of the expensive self-consistent procedures for DMRG-SCF. Several useful chemical indices are derived based on the occupation numbers of the natural orbitals for seamless continuation from broken-symmetry (BS) to symmetry-adapted (SA) methods. These procedures are used on 1,3-didehydrobenzene (meta-benzyne) to calculate its singlet (S)-triplet (T) gap. We compare our results to available experiments and computational results obtained by several other groups. We see our procedures as a seamless bridge between single-reference BS methods, such as UHDFT, and the SA MR methods, such as FV DMRG and MkMRCC. 相似文献
959.
Hazime Sait
Satoru Tuzi Katsuyuki Nishimura Akira Fukutani Akira Naito 《Macromolecular Symposia》1996,101(1):71-79
We examined conformation and dynamics of a variety of fibrous and membrane proteins by means of the conformation-dependent displacements of 13C nuclear magnetic resonance (NMR) chemical shifts and their relaxation parameters, respectively, as recorded by high-resolution solid-state 13C NMR. Determination of three-dimensional structure of atomic resolution is also briefly described for a simple peptide on the basis of precise measurements of interatomic distances. 相似文献
960.
Molecular dynamics simulation is used to investigate the crystallization of a classical two-dimensional electron system, in which electrons interact with the Coulomb repulsion. From the positional and the orientational correlation functions, we have found an indication that the solid phase has a quasi-long-range (power-law correlated) positional order and a long-range orientational order. This implies that the long-range 1/r system shares the absence of the true long-range crystalline order at finite temperatures with short-range ones to which Mermin's theorem applies. We also discuss the existence of the “hexatic” phase predicted by the Kosterlitz–Thouless–Halperin–Nelson–Young theory. 相似文献