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121.
用氯离子电极同时测定阳离子表面活性剂的CMC及反离子缔合度 总被引:5,自引:4,他引:5
临界胶束浓度(CMC)是研究表面活性剂的一个重要参数,胶束的反离子缔合度(K)是重要的特性参数。本文以阳离子表面活性剂十烷基三甲基氯化铵(DTMAC)、十二烷基三甲基氯化铵(DTAC)、十四烷基三甲基氯化铵(TTAC)、十六烷基三甲基氯化铵(CTAC)和十八烷基三甲基氯化铵(OTAC)水溶液体系为研究对象,用氯离子选择电极分别测定了其水溶液体系胶束的CMC和K。 相似文献
122.
报道了有机化合物极谱催化波的一种新类型--缔合/平行催化氢波.研究麦迪霉素-H2O2体系缔合/平行催化氢波的结果表明,质子化麦迪霉素与H2O2形成缔合物,引起峰电位负移;麦迪霉素催化氢波被H2O2还原中间产物羟基自由基进一步催化,使峰电流显著增加.求得麦迪霉素-H2O2缔合物的缔合比为1:1,表观缔合常数为7.18.在0.15 mol·L-1 KH2PO4-NaOH (pH 7.4)-0.02 mol·L-1 H2O2支持电解质中,-1.59 V (vs. SCE)处的缔合/平行催化氢波二阶导数峰峰电流与麦迪霉素浓度在2.0×10-8~1.0×10-5 mol·L-1范围内呈线性关系,检测限为6×10-9 mol·L-1.与麦迪霉素的催化氢波相比,该缔合/平行催化氢波提高分析灵敏度两个数量级. 相似文献
123.
利用红外、拉曼光谱技术和密度泛函理论研究了高浓度四氟硼酸钠/二甲基亚砜(DMSO)溶液中的离子溶剂化和离子缔合现象。红外和拉曼光谱分析表明,Na^ 与DMSO分子间有较强的相互作用.这种相互作用破坏了DMSO分子间的缔合,改变了DMSO分子的微观结构,使DMSO分子的谱带发生了明显的变化.对Na^ 与DMSO分子相互作用的溶剂化构型的量子化学计算表明,Na^ 与DMSO分子的相互作用是通过S-O基团上的氧原子进行的,钠离子的溶剂化数为4.另外,BF4^-离子的v1谱带的分裂表明,溶液中存在着直接接触离子对,形成的Na^ BF4^-离子对具有Cs构型. 相似文献
124.
Lianwei Li Xu Wang Chen He Weidong He 《Journal of polymer science. Part A, Polymer chemistry》2014,52(1):128-138
Amphiphilic hyperbranched copolymer chains made of large hyperbranched poly(acrylic acid) cores grafted with short polystyrene stickers (HB‐PAAn‐g‐PSn + 1) with different n values (n = 1, 10, 47) were well prepared and confirmed by size exclusion chromatography, Fourier transform infrared spectroscopy and 1H nuclear magnetic resonance. The study on the interchain association behavior of these amphiphilic chains indicates that larger HB‐(PAA)n‐g‐(PS)n + 1 copolymer chains have a less tendency to undergo interchain association. Moreover, the simple vial‐inversion and rheological experiments show that the apparent critical gel concentration (Cg) decreases with n, but no sol–gel transition was observed for triblock PS‐PAA‐PS even when the concentration is up to 200 g L?1. Further transmission electron microscopy study of the latex particles prepared with HB‐(PAA)n‐g‐(PS)n + 1 as surfactant reveals that the latex particles are spherical and narrowly dispersed; while the measured latex particle number (Np) indicates the surfactant efficiency of HB‐(PAA)47‐g‐(PS)48 is poorer than that of triblock PS‐PAA‐PS (n = 1). Finally, pyrene solubilization measurement shows the solubilization efficiency of HB‐(PAA)n‐g‐(PS)n + 1 copolymers decreases with n, consistent with the previous observed interchain association result. The present study demonstrates that both the chain topology and the styrene weight fraction dominates the final solution properties of amphiphilic HB‐(PAA)n‐g‐(PS)n + 1 chains in aqueous solution. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 128–138 相似文献
125.
A 1H NMR spectroscopic study of tetra-n-butylammonium halides (TBAX: X = Cl? , Br? or I? ) in CDCl3 solutions was conducted. Complexation studies of TBAX salts with different host molecules using 1H NMR in CDCl3 have previously revealed that the reference residual CHCl3 proton signal had been shifted downfield. The aim of the study was to quantify the extent of these chemical shift changes with TBAX salts. Linear concentration–chemical shift relationships in each case were obtained from the resulting titration plots obtained from the addition of the TBAX salts alone to CDCl3. Interactions in the solid state as determined by X-ray crystallography support the solution-state investigations indicating halide ion–chloroform proton interactions. 相似文献
126.
Homo‐double helix formation of an optically active conjugated polymer bearing carboxy groups and amplification of the helicity upon complexation with achiral and chiral amines 下载免费PDF全文
Wataru Makiguchi Shinzo Kobayashi Keisuke Furukawa Hiroki Iida Yoshio Furusho Eiji Yashima 《Journal of polymer science. Part A, Polymer chemistry》2015,53(8):990-999
An optically active, m‐terphenyl‐based π‐conjugated polymer bearing carboxy groups was synthesized by the copolymerization of the diethynyl monomer bearing a carboxy group with (S,S)‐2,5‐bis(2‐methylbutoxy)‐1,4‐dibromobenzene using Sonogashira reaction. The copolymer showed a weak circular dichroism (CD) in the main‐chain chromophore region due to a homo‐double helix formation with an excess helical handedness biased by the chiral alkoxy substituents through self‐association. However, upon complexation with achiral amines, such as piperidine, the CD intensity of the polymer significantly increased resulting in the formation of a greater excess one‐handed homo‐double helix via hydrogen‐bonded inclusion complexation with the achiral amines between each strand, leading to the amplification of the helicity. A preferred‐handed homo‐double helix was also induced in the polymer in the presence of nonracemic amines. The effect of the achiral and chiral amines on the homo‐double helix formation was investigated by comparing the CD spectra of the polymer to those of its model dimer. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 990–999 相似文献
127.
Interactions of three types of tetraalkylammonium cations (tetrapropyltetrabutyl-and tri-isoamylbutyl- ammonium) with perchlorate and tetraphenylborate anions were studied by the conductivity method in 2-butanone from –45°C to 25°C. Conductance data obtained for diluted solutions (5×10–5 – 2×10–3 mol-dm–3) were used to calculate the limiting molar conductivities and associationconstants. The conductance equation of Fuoss-Hsia including the Chen term and the chemical model assumption were applied. Limiting ion conductivities were calculated assuming equal limiting conductivities of the i-Am3BuN+ and BPh
4
–
ions at all temperatures. Gibbs energies and entropies of ion pair formation, calculated from the dependence of association constants on temperature, are presented including the contributions due to short-range forces. 相似文献
128.
Reynaldo C. Castells Eleuterio L. Arancibia Angel M. Nardillo 《Journal of solution chemistry》1993,22(1):85-94
The retention behavior of eight halomethanes and four saturated hydrocarbons was measured in gas chromatographic stationary phases consisting in tri-n-octylamine (TOA), squalane (SQ) and six TOA+SQ mixtures, at 55.0, 58.5, 62.5 and 65.0°C. Equlibrium constants for complex formation were extracted from experimental data by using a lattice model developed by Martire. The results may be interpreted in terms of the formation of weak hydrogen-bonded complexes, with sociation constants of about 0.13 L-mol–1 for haloforms and 0.07 L-mol–1 for dihalomethanes at 60°C. 相似文献
129.
Kevin Hing-Nin Poon Yu-Ling Cheng 《Journal of inclusion phenomena and macrocyclic chemistry》2008,60(3-4):211-222
Quartz crystal microbalance (QCM) was used to study the self-assembly of per-6-thio-β-cyclodextrin (t7-βCD) on gold surfaces, and the subsequent inclusion interactions of immobilized βCD with adamantane-poly(ethylene glycol)
(5,000 MW, AD-PEG), 1-adamantanecarboxylic acid (AD-C) and 1-adamantylamine (AD-A). From a 50 μM solution of t7-βCD in 60:40 DMSO:H2O, a t7-βCD layer was formed on gold with surface density of 71.7 ± 2.7 pmol/cm2, corresponding to 80 ± 3% of close-packed monolayer coverage. Gold sensors with immobilized t7-βCD were then exposed alternately to six different concentrations of AD-PEG, 500 μM AD-C or 500 μM AD-A aqueous solutions
for association, and water for dissociation. Association of AD-PEG conformed to a Langmuir isotherm, with a best fit equilibrium
constant K = 125,000 ± 18,000 M−1. For AD-C and AD-A, association (k
a
) and dissociation (k
d
) rate constants were extracted from kinetic profiles by fitting to the Langmuir model, and equilibrium constants were calculated.
The parameters for AD-C were found to be: k
a
= 100 ± 5 M−1 s−1, k
d
= 110 (±18) × 10−4 s−1, and K = 9,400 ± 1,700 M−1. For AD-A, k
a
= 58 ± 6 M−1 s−1, k
d
= 154 (±7) × 10−4 s−1, and K = 3,800 ± 400 M−1. The results demonstrate the utility of QCM as a tool for studying small molecule surface adsorption and guest–host interactions
on surfaces. More specifically, the kinetic and thermodynamic data of AD-C, AD-A, and AD-PEG inclusion with immobilized t7-βCD form a basis for further surface association studies of AD-X conjugates to advance surface sensory and coupling applications. 相似文献
130.
The association between hydrophobically modified poly(sodium acrylate) (HMPA) and poly(N-isopropylacrylamide) (PNIPAM) in aqueous solution was studied using turbidimetry, viscometry and fluorescence measurements. Both the polymeric and the amphiphilic nature of the HMPA influence the association process. The tendency for association, as reflected by the increase in the cloud point and the reduced viscosity of PNIPAM, increases with the length of the alkyl group and the degree of substitution of HMPA. The fluorescence study, using pyrene as a probe, ascertains that the association is of hydrophobic nature and the association process is gradual and less cooperative than the association of PNIPAM with ionic surfactants. When high molar mass HMPA is used, the hydrophobic association between HMPA and PNIPAM leads to the formation of a reversible network with significantly enhanced thickening properties as compared to the thickening ability of the corresponding pure HMPA in aqueous solution. 相似文献