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41.
Eva Schneiderman Bruno Perly Elwood Brooks Apryll M. Stalcup 《Journal of inclusion phenomena and macrocyclic chemistry》2002,43(1-2):43-50
The characterization of binary and ternary complexes of benzoate, lauryl hexaoxyethylene (C12E6) and -CD is presented. The complexation equilibrium was characterized by UV-Vis spectrophotometry, titration microcalorimetry, capillary electrophoresis, and 2D ROESY 1H-NMR. Results suggested that -CD forms one complex with C12E6in the stoichiometric ratio of -CD : C12E61.5 : 1, with a stability constant 1.3 × 105 M-1.5. The 2-D ROESY 1H-NMR spectrum indicated that C12E6is included inside the -CD cavity. The primary binding site of C12E6 is on the lauryl subunit of this molecule. Analogous to a previously reported study of -CD, the combination of -CD and C12E6precipitated from the solution. Addition of benzoate seemed to dissolve the precipitate and nearly doubled the apparent stability constant of the complex. Results from the various techniques supported formation of ternary complexes between -CD, C12E6, and benzoate. 相似文献
42.
Unlike micelles of straight hydrocarbon chain-surfactants, isoprenoid surfactants, CH3 [CH(CH3)CH2CH2CH2]3 CH(CH3)CH2–R (R=CH2N+ (CH3)3 Br–, CH2OPO3H– Na+, CH2OSO
3
–
Na+, CO
2
–
Na+), gave large globular and cellular assemblies in water which could be observed directly by transmission electron microscopy; critical micelle concentration of 0.31.4×10–3 M at 20°C, aggregation number of 215×104, and diameter of 200–2000 Å. A basic structure of the assemblies was a thin layer with a thickness (about 30 Å) which was close to the molecular length of the surfactants. The assemblies were decomposed during gel column chromatography; viz., they were not as stable as the liposomes of lecithins. The morphology was discussed in conjunction with a steric effect of the isoprenoid chain. 相似文献
43.
《Electroanalysis》2006,18(22):2243-2250
This work is focused on the voltammetric examination of the ion exchange properties of a smectite type clay, before and after its modification by the replacement of its native interlamellar cations (Na+, K+, Ca2+) by hexadecyltrimethylammonium cations (HDTMA+). The raw clay and its organically modified form were first characterized by X‐ray diffraction (XRD) and N2 adsorption–desorption isotherms (BET method) that confirmed the modification via an intercalation process. These materials were subsequently coated onto glassy carbon surfaces, and the resulting modified electrodes were evaluated for the uptake of [Ru(NH3)6]3+ and [Fe(CN)6]3? ions used as redox probes. Some experimental parameters affecting the incorporation of the probes within the film, including the ionic strength, the surfactant loading and the solution pH are thoroughly examined, in order to highlight the mechanism of the process. The possibility of using the surfactant‐intercalated clay modified electrode as an electrochemical sensor for [Fe(CN)6]3? is also evaluated. 相似文献
44.
45.
46.
47.
The effect of the addition of n-butanol (BuOH) and n-hexanol (HexOH) on the micellization of sodium dodecylsulfate (SDS) has been investigated using fluorescence quenching methods.
The binding constants were calculated using an expression which relates the total concentration of alcohols and the micelle
concentration. The values of K were 4.67 and 17.6 M-1 for BuOH/SDS and HexOH/SDS, similar to values obtained by other methods. The cmc of SDS decreases on addition of alcohols
and goes through a minimum for the BuOH/SDS system. Micellar aggregation numbers (N) were determined from linear plots of Ln (I
0/I) against [Quencher] at low alcohol concentrations. For 15 mM SDS, in the presence of BuOH the N values decrease on addition of alcohol up to 0.2 M. For HexOH, N can be assumed to be constant up to 4.8 mM, after which N decreases. The polarity of the micellar core containing alcohol was evaluated from the I
1/I
3 ratio of monomeric pyrene. The effect of addition of the alcohol causes a decrease in the I
1/I
3, which corresponds to a decrease in the polarity of the pyrene solubilization site.
Received: 28 October 1996 Accepted: 10 January 1997 相似文献
48.
Artificial red cells with crosslinked hemoglobin membranes 总被引:1,自引:0,他引:1
Thomas A. Davis William J. Asher Herbert W. Wallace 《Applied biochemistry and biotechnology》1984,10(1-3):123-132
Artificial cells containing concentrated hemoglobin (Hb) solution were prepared by interfacial polymerization of Hb with glutaraldehyde
(GA) in liquid membrane capsules (LMC). A solution containing 30% of Hb was emulsified in mineral oil as red cell-size microdroplets,
and this emulsion was dispersed in an aqueous phase containing glutaraldehyde to form LMC. The LMC were semipermeable templates
that held the microdroplets of Hb in suspension while GA diffused through the oil to the microdroplet surfaces. The GA crosslinked
Hb at the surface of each microdroplet to form an artificial red-cell membrane encapsulating Hb solution. A water-soluble
surfactant was used to eject the cells from the LMC and suspend them in saline.
Several surfactants were evaluated. Cell size was controlled by agitation speed during preparation of the original emulsion.
Cells of 2.52 = ±1.69 μm were prepared. The encapsulated Hb retained capacity to bind and release O2. The cells had aP
50 of 8.9 torr (1200 Pa) and a capacity of 0.55 cc O2/g of total Hb, indicating that the crosslinked portion of the Hb did not contribute to O2 transport. 相似文献
49.
Bhowmik BB Ganguly P 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2005,62(4-5):808-813
The spectral (both absorption and fluorescence) and photoelectrochemical studies of a few selective dyes, namely, anionic erythrosin B, neutral riboflavin and cationic safranin O have been carried out in aqueous solution of triton X-100, a neutral surfactant. The results show that the ionic dyes, erythrosin B and safranin O form 1:1 electron donor-acceptor (EDA) or charge-transfer (CT) complexes with triton X-100 both in the ground and excited states, whereas neutral dye riboflavin in its excited state forms 1:1 complex with triton X-100. In these complexes, the dyes act as electron acceptors whereas triton X-100 acts as an electron donor. The fluorescence spectra of erythrosin B and safranin O in presence of triton X-100 show enhancement of fluorescence intensity with red and blue shifts respectively while riboflavin shows normal quenching of fluorescence. A good correlation has been found among photovoltage generation of the systems consisting of these dyes and triton X-100, spectral shift due to complex formation and thermodynamic properties of these complexes. 相似文献
50.
Colloidal silica and titanium dioxide were surface-modified by chemisorption of octadecyl dimethylmethoxy silane. The surface density of these alkyl silane groups was adjusted to less than 7% of the available surface hydroxyls, leaving the adsorbents hydrophilic and electrically charged in aqueous solution.Ionic surfactants (tetradecylpyridinium chloride and sodium lauryl sulfate) are adsorbed onto the surface-modified silica and titanium dioxide from aqueous solution, even in the case where the surface of the adsorbents exhibits the same sign of electrical charge as the surfactant ionic head groups. According to the adsorption model of Gu the chemiadsorbed alkyl chains are supposed to serve as anchors for small surface aggregates of the ionic surfactants. 相似文献