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101.
Self‐Assembly of Pyridinium‐Functionalized Anthracenes: Molecular‐Skeleton‐Directed Formation of Microsheets and Microtubes 下载免费PDF全文
Dr. Jun Hu Peiyi Wang Prof. Yuan Lin Prof. Jidong Zhang Dr. Mark Smith Dr. Perry J. Pellechia Prof. Song Yang Prof. Baoan Song Prof. Qian Wang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(25):7603-7607
Two amphiphilic regioisomers, 9‐AP (1‐[11‐(9‐anthracenylmethoxy)‐11‐oxoundecyl]pyridinium bromide), and 2‐AP (1‐[11‐(2‐anthracenyl methoxy)‐11‐oxoundecyl]pyridinium bromide), were synthesized and their assembly behaviors were studied. Due to the anisotropic features of the anthracene structure, different substituted positions on the anthracene ring lead 9‐AP and 2‐AP to adapt “shaver” and “spatula”‐like molecular shapes, respectively, which consequently dictate the structure of their final assemblies. While “shaver”‐shaped 9‐AP assembled into microsheets, driven by π–π interactions, “spatula”‐shaped 2‐AP assembled into microtubular structures, promoted primarily by charge‐transfer interactions. 相似文献
102.
Honglin Li Fengyu Liu Yi Xiao Perry J. Pellechia Mark D. Smith Xuhong Qian Guiren Wang Qian Wang 《Tetrahedron》2014
We have revisited the synthesis of a series of ICT fluorophores, which were reported to have a core structure of 8-oxo-8H-acenaphtho[1,2-b]pyrrol-9-carbonitrile. However, based on the 2D NMR and X-ray diffraction analysis, their core structure was corrected as 1-oxo-1H-phenalene-2,3-dicarbonitrile (1). Compound 1 shows a highly electron-deficient nature and can easily undergo oxidative SNArH reaction on the naphthyl ring to produce a series of novel ICT fluorophores. The regioselectivity of this substitution reaction was studied by introduction of representative nucleophiles. Moreover, due to the strong rigidity and efficient ICT nature, the obtained fluorescent dyes display very good spectroscopic properties even in an aqueous environment. 相似文献
103.
Shun-Yang Yu Yan-Cang Li Tao Xiong Qun Yuan Yong-Ming Liu Zhong-Yi Yuan Yi Xiao 《中国化学快报》2014,25(2):364-366
In recent years, there has been a pronounced interest in solid-contact ion-selective electrodes (SC-ISEs), with emphasis on the use of conducting polymers as ion-to-electron transducer. In this work, a ladder conjugated polymer, thieno[3,2-b]thiophene (LCPT), was investigated in fabricating Cu2+-selective electrodes for the first time. The resulting electrodes were characterized by electrochemical impedance spectroscopy (EIS), chronopotentiometry, and the water layer test. Results proved that the active LCPT facilitates the ion-to-electron transduction, and avoids the detrimental aqueous layer formed at the interface of SC-ISEs. 相似文献
104.
This paper deals with the structure of essentially disconnected polyomino graphs. It is proved that for an essentially disconnected
polyomino graph, the normal components induced digraph is acyclic and connected. The lower bond for the number of normal components
of an essentially disconnected polyomino graph is investigated. Moreover, the essentially disconnected polyomino graphs with
two or three normal components are classified and constructed. 相似文献
105.
Richard D. Adams Fang Fang Mark D. Smith Qiang Zhang 《Journal of organometallic chemistry》2011,696(17):2904-2909
A reinvestigation of the reaction of Ir(CO)Cl(PPh3)2, 1 with HSnPh3 has revealed that the oxidative-addition product Ir(CO)Cl(PPh3)2(H)(SnPh3), 2 has the H and SnPh3 ligands in cis-related coordination sites. Compound 2 reacts with a second equivalent of HSnPh3 by a Cl for H ligand exchange to yield the new compound H2Ir(CO)(SnPh3)(PPh3)2, 3. Compound 3 contains two cis- related hydride ligands. Under an atmosphere of CO, 1 reacts with HSnPh3 to replace the Cl ligand with SnPh3 and one of the PPh3 ligands with a CO ligand and also adds a second equivalent of CO to yield the 5-coordinate complex Ir(CO)3(SnPh3)(PPh3), 4. Compound 4 reacts with HSnPh3 by loss of CO and oxidative addition of the Sn-H bond to yield the 6-coordinate complex HIr(CO)2(SnPh3)2(PPh3), 5 that contains two trans-positioned SnPh3 ligands. 相似文献
106.
《International Journal of Plasticity》2005,21(1):83-99
A kinematic, stress, and hardening analysis of finite double slip in fcc crystals under axial loading is presented. The relative amounts of slip in classic 1925 experiments by Taylor and Elam (determined analytically in [Int. J. Plasticity 9 (1993) 159–179] by comparing theoretical and experimental cones of unextended directions), together with load-extension data and other measurements, are used to calculate resolved shear stress vs. slip curves and assess predictions of several finite distortional hardening theories. In particular, a new hardening rule is introduced that gives very close agreement with the anisotropic experimental results in double slip yet is consistent with the axisymmetric deformation, lattice stability, and isotropic hardening that are characteristic of fcc and bcc crystals in high symmetry axial-load orientations involving 6- and 8-fold slip. 相似文献
107.
Sudhir?S.?Shenoy Norman?J.?WagnerEmail author Jonathan?W.?Bender 《Rheologica Acta》2003,42(4):287-294
A novel electrorheological (ER) effect is presented where the application of an electric field, orthogonal to the vorticity-flow plane, increases the critical hydrodynamic stress required to shear thicken concentrated, colloidal dispersions (the E-FiRST effect). The shear thickening behavior of a Brownian charge stabilized dispersion (226 nm silica in 4-methylcyclohexanol at 53, 50. and 41 vol.%) is studied in the presence of an electric field as a function of the field strength and coupling parameter ( ß) where the latter is a function of a.c. field frequency due to diffusion limitations on the polarization of the particles' double layer. A mechanism is proposed whereby the applied electric field suppresses the formation of the self-organized hydrocluster microstructure responsible for shear thickening, thus delaying the onset of shear thickening to higher applied shear stresses. A Mason-number type scaling law is found to scale the effect, which supports the proposed mechanism. 相似文献
108.
Praneshwar Sethupathy Inas M. Alnashef John R. Monnier Michael A. Matthews John W. Weidner 《合成通讯》2013,43(24):3632-3647
Abstract We show that the superoxide ion (O2 ??) generated electrochemically from oxygen dissolved in room-temperature ionic liquids (RTILs) reacts with primary and secondary alcohols to form the corresponding ketones and carboxylic acids, respectively. Specifically, we study the conversion of benzhydrol to benzophenone and benzyl alcohol to benzaldehyde/benzoic acid. The kinetics (e.g., rate, selectivity, and yield) for these reactions are also determined as functions of the variations in the structure of the ionic liquids. The RTILs used here are imidazolium-based cations where the functional groups on the imidazolium ring are modified. Specifically, 1-butyl-3-methylimidazolium hexafluorophosphate [bmim][PF6], 1-butyl-2,3-dimethylimidazolium hexafluorophosphate [bdmim][PF6], and 1-hexyl-3-methylimidazolium hexafluorophosphate [hmim][PF6] are used as the reaction medium. These results are compared to an ammonium-based RTIL (N-butyl-N-trimethylammonium bis(trifluoromethylsulfonyl)imide). The results show that the nucleophilic attack by the O2 ?? of both the RTIL and the alcohol, especially that of the H atom at the R2 position of the [bmim][PF6] and [hmim][PF6], greatly affects the yields. No RTIL degradation products were detected for the reactions in [bdmim][PF6] and N-butyl-N-trimethylammonium bis(trifluoromethylsulfonyl)imide ionic liquids. For the benzyl alcohol oxidation reaction in the RTIL, N-butyl-N-trimethylammonium bis(trifluoromethylsulfonyl)imide, benzaldehyde formed did not undergo further oxidation to form benzoic acid, which may be due to the greater hydrophobicity of this RTIL. The competitive reaction kinetics between the alcohol and RTIL component must be considered in the selection of the RTIL solvent system. 相似文献
109.
The azido sugar,GalNAz,was successfully used for imaging and perturbing protein glycosylation in triple-negative breast cancer cell line,MDA-MB-231.After the incorporation of GalNAz in the triple-negative breast cancer cell line,the tumorigenicity of these cells was decreased.Results from gene analysis and drug treatment suggest that the tumorigenicity decrease may be attributed to the reduction of cancer stem cell population.Possible mechanisms of GalNAz induced cancer stem cells(CSCs) proportion change are discussed. 相似文献
110.
Jifu Wang Kejian Yao Andrew L. Korich Shigeng Li Shuguo Ma Harry J. Ploehn Peter M. Iovine Chunpeng Wang Fuxiang Chu Chuanbing Tang 《Journal of polymer science. Part A, Polymer chemistry》2011,49(17):3728-3738
Rosin polymer–grafted lignin composites were prepared via “grafting from” atom transfer radical polymerization (ATRP) with the aid of 2‐bromoisobutyryl ester‐modified lignin as macroinitiators. Three different monomers derived from dehydroabietic acid (DA) were used for execution of grafting from ATRP, while DA was separately attached onto lignin by a simple esterification reaction. Kinetic studies indicated controlled and “living” characteristics of all monomer polymerizations. Thermal studies indicated that rosin polymer–grafted lignin composites exhibited glass transition temperatures in a broad temperature range from ~20 to 100°C. The grafting of both DA and rosin polymers significantly enhanced hydrophobicity of lignin. Static contact angle measurement of water droplets showed ~90° for all these rosin modified lignin composites. X‐ray photoelectron spectroscopy demonstrated that the surface of rosin–lignin composites was dominated with chemical compositions originating from the hydrocarbon rich rosin moiety. The impartation of hydrophobicity of rosin into lignin provided excellent water resistance of this class of renewable polymers, as all rosin‐modified lignin composites showed water uptake below 1.0 wt %. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011 相似文献