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171.
Even at ambient temperature or less, below their 0.2% proof stresses all hexagonal close-packed metals and alloys show creep behaviour because they have dislocation arrays lying on a single slip system with no tangled dislocation inside each grain. In this case, lattice dislocations move without obstacles and pile-up in front of a grain boundary. Then these dislocations must be accommodated at the grain boundary to continue creep deformation. Atomic force microscopy revealed the occurrence of grain boundary sliding (GBS) in the ambient-temperature creep region. Lattice rotation of 5° was observed near grain boundaries by electron backscatter diffraction pattern analyses. Because of an extra low apparent activation energy of 20 kJ/mol, conventional diffusion processes are not activated. To accommodate these piled-up dislocations without diffusion processes, lattice dislocations must be absorbed by grain boundaries through a slip-induced GBS mechanism. 相似文献
172.
Takahiro Yonezawa Tatsuya Murakami Koichi Higashimine Antoine Fleurence Yoshifumi Oshima Yukiko Yamada-Takamura 《Surface and interface analysis : SIA》2019,51(1):95-99
Layered materials can be grown on various substrates through van der Waals epitaxy (vdWE) regardless of lattice mismatch. The atomistic study of the film-substrate interface in vdWE is becoming increasingly important due to their expected applications as two-dimensional (2D) materials. In this contribution, we have grown GaSe thin films on Ge(111) substrates by molecular beam epitaxy and studied the GaSe/Ge(111) interface using high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM). Cross-sectional HAADF-STEM observations revealed that the grown layers adopt predominantly the expected wurtzite-like structure and stacking, but layers with zinc-blende-like structure, similar to Ga2Se3 but apparently different, and other layer stacking sequences, exist locally near the film-substrate interface. These results demonstrate that even in vdWE, structural changes can occur in the grown layers adjacent to the substrate, highlighting the importance of such interface for synthesizing and applying ultimately thin 2D materials. 相似文献
173.
Tatsuya Iioka Satoshi Takahashi Yuichiro Yoshida Yoshihiro Matsumura Shuichi Hiraoka Hirofumi Sato 《Journal of computational chemistry》2019,40(1):279-285
The kinetics on a basic ligand substitution reaction on dinuclear platinum complexes [Pt(PEt3)2PhPt(PEt3)2]2+ and [Pt(PEt3)2PhCOPhPt(PEt3)2]2+ , with the ligands pyridine and 3-chloropyridine, is studied. This is a fundamental step in a self-assembly, and the time evolution has been observed with a new experimental technique, QASAP (quantitative analysis of self-assembly process), which is recently developed by Hiraoka's group. As a result of numerical calculations based on master equation, we succeed in specifying the reaction rate constants with a simple reaction model. In addition, the time evolutions of all the intermediate components produced and consumed in chemical reaction are revealed, including those unobserved in the experiments. The convergence behavior of the existence ratios of specific chemical species calculated with the stochastic algorithm method is compared with those obtained from deterministic formalism based on rate equations, revealing a clear dependence on the number of constituent molecules. © 2018 Wiley Periodicals, Inc. 相似文献
174.
Tatsuya Sakakura Assoc. Prof. Naoya Murakami Dr. Yoshiyuki Takatsuji Masayuki Morimoto Prof. Tetsuya Haruyama 《Chemphyschem》2019,20(11):1467-1474
Electric-discharge nitrogen comprises three main types of excited nitrogen species-atomic nitrogen (Natom), excited nitrogen molecules (N2*), and nitrogen ions (N2+) – which have different lifetimes and reactivities. In particular, the interfacial reaction locus between the discharged nitrogen and the water phase produces nitrogen compounds such as ammonia and nitrate ions (denoted as N-compounds generically); this is referred to as the plasma/liquid interfacial (P/L) reaction. The Natom amount was analyzed quantitatively to clarify the contribution of Natom to the P/L reaction. We focused on the quantitative relationship between Natom and the produced N-compounds, and found that both N2* and N2+, which are active species other than Natom, contributed to P/L reaction. The production of N-compounds from N2* and N2+ was enhanced upon UV irradiation of the water phase, but the production of N-compounds from Natom did not increase by UV irradiation. These results revealed that the P/L reactions starting from Natom and those starting from N2* and N2+ follow different mechanisms. 相似文献
175.
Conventionally, the Fourier transform is applied for sound intensity analysis of stationary signals, but this method can be applied for analyzing non-stationary transient signals. Instead of the Fourier transform analysis, instantaneous spectrum analysis methods such as the Wigner-Ville distribution and the wavelet transform are proposed. By using the mathematical example as a transient signal, advantages and disadvantages of these methods including the short-time Fourier transform are compared. From calculation results, it is considered that the STFT method is the most suitable for the accurate measurement of sound intensity levels, but the WT method is also recommended from its higher resolution of transient signals. 相似文献
176.
Frontispiece: An Optically and Thermally Switchable Electronic Structure Based on an Anthracene–BODIPY Conjugate 下载免费PDF全文
177.
Kanna Adachi Tomoshi Yamada Hayate Ishizuka Mana Oki Shunsuke Tsunogae Noriko Shimada Osamu Chiba Tatsuya Orihara Prof. Dr. Masafumi Hidaka Prof. Dr. Takatsugu Hirokawa Dr. Minami Odagi Prof. Dr. Keiichi Konoki Prof. Dr. Mari Yotsu-Yamashita Prof. Dr. Kazuo Nagasawa 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(9):2025-2033
A novel series of C12-keto-type saxitoxin (STX) derivatives bearing an unusual nonhydrated form of the ketone at C12 has been synthesized, and their NaV-inhibitory activity has been evaluated in a cell-based assay as well as whole-cell patch-clamp recording. Among these compounds, 11-benzylidene STX ( 3 a ) showed potent inhibitory activity against neuroblastoma Neuro 2A in both cell-based and electrophysiological analyses, with EC50 and IC50 values of 8.5 and 30.7 nm , respectively. Interestingly, the compound showed potent inhibitory activity against tetrodotoxin-resistant subtype of NaV1.5, with an IC50 value of 94.1 nm . Derivatives 3 a – d and 3 f showed low recovery rates from NaV1.2 subtype (ca 45–79 %) compared to natural dcSTX ( 2 ), strongly suggesting an irreversible mode of interaction. We propose an interaction model for the C12-keto derivatives with NaV in which the enone moiety in the STX derivatives 3 works as Michael acceptor for the carboxylate of Asp1717. 相似文献
178.
Dr. Hajime Kameo Tatsuya Kawamoto Prof. Shigeyoshi Sakaki Prof. Didier Bourissou Prof. Hiroshi Nakazawa 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(7):2370-2375
Si?F bond cleavage of fluoro‐silanes was achieved by transition‐metal complexes under mild and neutral conditions. The Iridium‐hydride complex [Ir(H)(CO)(PPh3)3] was found to readily break the Si?F bond of the diphosphine‐ difluorosilane {(o‐Ph2P)C6H4}2Si(F)2 to afford a silyl complex [{[o‐(iPh2P)C6H4]2(F)Si}Ir(CO)(PPh3)] and HF. Density functional theory calculations disclose a reaction mechanism in which a hypervalent silicon species with a dative Ir→Si interaction plays a crucial role. The Ir→Si interaction changes the character of the H on the Ir from hydridic to protic, and makes the F on Si more anionic, leading to the formation of Hδ+???Fδ? interaction. Then the Si?F and Ir?H bonds are readily broken to afford the silyl complex and HF through σ‐bond metathesis. Furthermore, the analogous rhodium complex [Rh(H)(CO)(PPh3)3] was found to promote the cleavage of the Si?F bond of the triphosphine‐monofluorosilane {(o‐Ph2P)C6H4}3Si(F) even at ambient temperature. 相似文献
179.
180.
Prof. Dr. Shigehisa Akine Masato Miyashita Prof. Dr. Tatsuya Nabeshima 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(6):1432-1435
A closed metallomolecular cage based on the tris(saloph) framework, in which its aperture can be opened by disulfide exchange, was designed. At the apertures of the molecular cage, bridging diamine ligands having a disulfide bond were introduced to close the cage structure. These bridging ligands efficiently blocked the uptake of a guest, Cs+, but the presence of a thiolate anion significantly accelerated the guest uptake. This clearly means that this cage complex became open by the addition of the thiolate anion, because the cage closure becomes more dynamic due to the disulfide exchange reaction. 相似文献