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41.
Zhi L Gorelik T Wu J Kolb U Müllen K 《Journal of the American Chemical Society》2005,127(37):12792-12793
Novel naphthalocyanine (Nc) nanotubes with special wall structures were fabricated by a template method using Nc molecules as building blocks. Thermal stabilization of the ordered columnar structures of the tetrakis(tert-butyl)naphthalocyanine (Ni-BNc) molecules, induced from the pi-pi interactions in the nanoscale channels of an alumina template, resulted in Nc nanotubes with walls consisting of well-ordered Nc molecular disks. Further thermal treatment of Ni-BNc at 600 degrees C produced carbonized Nc nanotubes containing ordered columnar, graphitic wall structures with the graphene disks arranged perpendicular to the tube axis. These nanotubes may be useful for extending the application of Nc molecules for nanodevice fabrication. 相似文献
42.
Piot L Marchenko A Wu J Müllen K Fichou D 《Journal of the American Chemical Society》2005,127(46):16245-16250
The growth and structure of self-assembled adlayers of hexakis(n-dodecyl)-peri-hexabenzocoronene (HBC-C12) adsorbed on highly ordered pyrolitic graphite (HOPG) decorated by an n-pentacontane (n-C50H102) monolayer have been investigated by scanning tunneling microscopy (STM). Whereas on HOPG the HBC-C12 molecules readily self-assemble into a unique stable 2D structure, on the [n-C50H102 monolayer/graphite] system we observe morphological phase transitions with formation of time dependent alpha, beta, and gamma phases (alpha-->beta-->gamma). The initial alpha-phase is similar to that obtained on bare graphite, while intermediate beta- and final gamma-structures present molecular dimers and rows, respectively. The observed two-dimensional polymorphism is due to weak interaction between HBC-C12 molecules and n-C50H102-modified graphite substrate. Our results constitute an important step toward the control of the growth and structure of highly ordered monolayers of functional conjugated molecules by modifying the graphite surface with an n-alkane monolayer of appropriate chain length. 相似文献
43.
Wangdong Zeng Dr. Masatoshi Ishida Sangsu Lee Young Mo Sung Dr. Zebing Zeng Yong Ni Prof. Chunyan Chi Prof. Dongho Kim Prof. Jishan Wu 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(49):16814-16824
A p‐quinodimethane (p‐QDM)‐bridged porphyrin dimer 1 has been prepared for the first time. An unexpected Michael addition reaction took place when we attempted to synthesize compound 1 by reaction of the cross‐conjugated keto‐linked porphyrin dimers 8 a and 8 b with alkynyl/aryl Grignard reagents. Alternatively, compound 1 could be successfully prepared by intramolecular Friedel–Crafts alkylation of the diol‐linked porphyrin dimer 14 with concomitant oxidation in air. Compound 1 shows intense one‐photon absorption (OPA, λmax=955 nm, ε=45400 M ?1 cm?1) and a large two‐photon absorption (TPA) cross‐section (σ(2)max=2080 GM at 1800 nm) in the near‐infrared (NIR) region due to its extended π‐conjugation and quinoidal character. It also exhibits a short singlet excited‐state lifetime of 25 ps. The cyclic voltammogram of 1 displays multiple redox waves with a small electrochemical energy gap of 0.86 eV. The ground‐state geometry, electronic structure, and optical properties of 1 have been further studied by density functional theory (DFT) calculations and compared with those of the keto‐linked dimer 8 b . This research has revealed that incorporation of a p‐QDM unit into the porphyrin framework had a significant impact on its optical and electronic properties, leading to a novel NIR OPA and TPA chromophore. 相似文献
44.
In this paper, we propose a predictor—corrector-type algorithm for solving the linear complementarity problem (LCP), and prove that the actual number of iterations needed by the algorithm is bounded from above and from below by a curvature integral along the central trajectory of the problem. This curvature integral is not greater than, and possibly smaller than, the best upper bound obtained in the literature to date.Corresponding author.This author's research was partially supported by Research Grant No. RP920068, National University of Singapore, Singapore. 相似文献
45.
本文给出了以第一类Chebyshev多项式的零点为节点的Hermitfe插值多项式来逼近函数及其导数时的逼近阶的点态估计式,该结果回答了谢庭藩教授在文[4]中提出的问提. 相似文献
46.
Yong Ni Dr. Tullimilli Y. Gopalakrishna Dr. Hoa Phan Dr. Tun Seng Herng Shaofei Wu Yi Han Prof. Jun Ding Prof. Jishan Wu 《Angewandte Chemie (International ed. in English)》2018,57(31):9697-9701
Peri‐acenes are good model compounds for zigzag graphene nanoribbons, but their synthesis is extremely challenging owing to their intrinsic open‐shell diradical character. Now, the successful synthesis and isolation of a stable peri‐tetracene derivative PT‐2ClPh is reported; four 2,6‐dichlorophenyl groups are attached onto the most reactive sites along the zigzag edges. The structure was confirmed by X‐ray crystallographic analysis and its electronic properties were systematically investigated by both experiments and theoretical calculations. It exhibits an open‐shell singlet ground state with a moderate diradical character (y0=51.5 % by calculation) and a small singlet–triplet gap (ΔES‐T=?2.5 kcal mol?1 by SQUID measurement). It displays global aromatic character, which is different from the smaller‐size bisanthene analogue BA‐CF3 . 相似文献
47.
We prove the uniqueness of weak solutions of the time-dependent 3-D Ginzburg-Landau model for superconductivity with (Ψ
0, A
0) ∈ L
2(Ω) initial data under the hypothesis that (Ψ, A) ∈ C([0, T]; L
3(Ω)) using the Lorentz gauge.
相似文献
48.
Z Zeng YM Sung N Bao D Tan R Lee JL Zafra BS Lee M Ishida J Ding JT López Navarrete Y Li W Zeng D Kim KW Huang RD Webster J Casado J Wu 《Journal of the American Chemical Society》2012,134(35):14513-14525
Stable open-shell polycyclic aromatic hydrocarbons (PAHs) are of fundamental interest due to their unique electronic, optical, and magnetic properties and promising applications in materials sciences. Chichibabin's hydrocarbon as a classical open-shell PAH has been investigated for a long time. However, most of the studies are complicated by their inherent high reactivity. In this work, two new stable benzannulated Chichibabin's hydrocarbons 1-CS and 2-OS were prepared, and their electronic structure and geometry in the ground state were studied by various experiments (steady-state and transient absorption spectra, NMR, electron spin resonance (ESR), superconducting quantum interference device (SQUID), FT Raman, X-ray crystallographic etc.) and density function theory (DFT) calculations. 1-CS and 2-OS exhibited tunable ground states, with a closed-shell quinoidal structure for 1-CS and an open-shell biradical form for 2-OS. Their corresponding excited-state forms 1-OS and 2-CS were also chemically approached and showed different decay processes. The biradical 1-OS displayed an unusually slow decay to the ground state (1-CS) due to a large energy barrier (95 ± 2.5 kJ/mol) arising from severe steric hindrance during the transition from an orthogonal biradical form to a butterfly-like quinoidal form. The quick transition from the quinoidal 2-CS (excited state) to the orthogonal biradicaloid 2-OS (ground state) happened during the attempted synthesis of 2-CS. Compounds 1-CS and 2-OS can be oxidized into stable dications by FeCl(3) and/or concentrated H(2)SO(4). The open-shell 2-OS also exhibited a large two-photon absorption (TPA) cross section (760 GM at 1200 nm). 相似文献
49.
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