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111.
112.
113.
Shaun Forteath Edith Antunes Wadzanai Chidawanyika Tebello Nyokong 《Journal of luminescence》2012,132(9):2318-2324
Zinc 2, (3)-tri-(phenylthio)-2, (3)-carboxy phthalocyanine (ZnPc(COOH)(SPh)3), zinc 2, (3)-tetra-(phenylthio) phthalocyanine (ZnPc(SPh)4) and 2, (3)-tetra-(phenylthio) phthalocyanine (H2Pc(SPh)4) were synthesized and their photophysical behavior were compared with those of a number of zinc phthalocyanine (ZnPc) derivatives. ZnPc(COOH)(SPh)3 and ZnPc(SPh)4 had similar fluorescence (ΦF=0.14) and triplet state (ΦT=0.65) quantum yields in dimethylsulfoxide, hence showing no effects of the replacement of one of the phenylthio groups with a carboxylic acid group. ZnPc(COOH)(SPh)3 displayed a slightly shorter triplet lifetime (τT=331 μs) than ZnPc (τT=350 μs) in DMSO, but within the range of ZnPc derivatives. The triplet lifetime for ZnPc(COOH)(SPh)3 is much longer than for the symmetrical derivative (ZnPc(SPh)4) with τT=149 μs in DMSO. 相似文献
114.
Andrew W. Owen Edith A.J. McAulay Alison Nordon David Littlejohn Thomas P. Lynch J. Steven Lancaster Robert G. Wright 《Analytica chimica acta》2014
A specially designed thermal vaporiser was used with a process mass spectrometer designed for gas analysis to monitor the esterification of butan-1-ol and acetic anhydride. The reaction was conducted at two scales: in a 150 mL flask and a 1 L jacketed batch reactor, with liquid delivery flow rates to the vaporiser of 0.1 and 1.0 mL min−1, respectively. Mass spectrometry measurements were made at selected ion masses, and classical least squares multivariate linear regression was used to produce concentration profiles for the reactants, products and catalyst. The extent of reaction was obtained from the butyl acetate profile and found to be 83% and 76% at 40 °C and 20 °C, respectively, at the 1 L scale. Reactions in the 1 L reactor were also monitored by in-line mid-infrared (MIR) spectrometry; off-line gas chromatography (GC) was used as a reference technique when building partial least squares (PLS) multivariate calibration models for prediction of butyl acetate concentrations from the MIR spectra. In validation experiments, good agreement was achieved between the concentration of butyl acetate obtained from in-line MIR spectra and off-line GC. In the initial few minutes of the reaction the profiles for butyl acetate derived from on-line direct liquid sampling mass spectrometry (DLSMS) differed from those of in-line MIR spectrometry owing to the 2 min transfer time between the reactor and mass spectrometer. As the reaction proceeded, however, the difference between the concentration profiles became less noticeable. DLSMS had advantages over in-line MIR spectrometry as it was easier to generate concentration profiles for all the components in the reaction. Also, it was possible to detect the presence of a simulated impurity of ethanol (at levels of 2.6 and 9.1% mol/mol) in butan-1-ol, and the resulting production of ethyl acetate, by DLSMS, but not by in-line MIR spectrometry. 相似文献
115.
One step alkaline synthesis of biocompatible gold nanoparticles using dextrin as capping agent 总被引:1,自引:0,他引:1
Michael J. Anderson Edith Torres-Chavolla Brian A. Castro Evangelyn C. Alocilja 《Journal of nanoparticle research》2011,13(7):2843-2851
Gold nanoparticles (AuNPs) are used in sensing methods as tracers and transducers. The most common AuNP synthesis techniques
utilize citrate under acidic reaction conditions. The synthesis described in this article generates glyco-AuNPs under mild
alkaline conditions providing a “greener” alternative to Brust and Turkevich methodologies. This biologically compatible one-step
technique uses dextrin as a capping agent and sodium carbonate as the reducing agent for chloroauric acid. The generated particles
were relatively mono-dispersed and water soluble with a range of controllable mean diameters from 5.9 to 16.8 ± 1.6 nm. The
produced AuNPs were stable in water for more than 6 months stored at room temperature (21 °C) in generation solution without
protection from light. This article shows the effect of temperature, pH, and dextrin concentration on the synthesis procedure
and AuNP diameter. These factors were found to control the reaction speed. The produced glyco-AuNPs were successfully functionalized
with DNA oligonucleotides, and the functionalization efficiency was similar to citrate-generated AuNPs. The alkaline synthesis
allows future exploration of simultaneous synthesis and functionalization procedures, which could significantly reduce the
time of current ligand exchange methodologies. 相似文献
116.
Emma Werz Rebecca Viere Gina Gassmann Sergei Korneev Edith Malecki Helmut Rosemeyer 《Helvetica chimica acta》2013,96(5):872-888
Three pyrimidine nucleosides, uridine ( 1 ), 5‐methyluridine ( 6 ), and 2′‐deoxythymidine ( 11 ), were converted to amphiphilic nucleolipids. Compounds 1 and 6 were lipophilized by introduction of symmetric ketal moieties with various carbon chain lengths (i.e., 5–17). Two ketal derivatives, 2b and 7a , were additionally further hydrophobized by N(3)‐farnesylation. 2′‐Deoxythymidine was alkylated at N(3) with a cetyl (=hexadecyl) residue, either directly or, after complete orthogonal protection of the sugar OH groups, by Mitsunobu reaction with hexadecan‐1‐ol. Some of the nucleolipids were subsequently converted to their 2‐cyanoethyl phosphoramidites (5′ or 3′), one of which was used for an exemplary synthesis of a lipo‐oligonucleotide. The sequence of this lipo‐oligonucleotide is an encoded manifestation of Pythagoras' law, created with a key table in which the letters of the alphabet, the numbers from 0 to 9 as well as the mostly used mathematical symbols are allocated to a ribonucleic acid triplet of the genetic code. 相似文献
117.
R. Fresenius und Edith Kroupa 《Fresenius' Journal of Analytical Chemistry》1941,121(3-4):138-139
Ohne Zusammenfassung 相似文献
118.
The starting point of this article is a generalized concept of affine space which includes all affine spaces over unitary modules. Our main result is a representation theorem for hyperplanes of affine spaces: Every hyperplane which satisfies a weak richness condition is induced by a module. 1 相似文献
119.
In this paper we obtain a generalized Hopf structure on the total space of certain principal circle bundles over a compact
cosympletic manifold. Using this result we give new examples of compact generalized Hopf manifolds. We describe these examples
as suspensions with fibre a compact quotient of the generalized Heisenberg groupH(n, 1) by a discrete subgroup and we show an explicit realization of them as compact solvmanifolds. 相似文献
120.
Phillips RS Miles EW McPhie P Marchal S Georges C Dupont Y Lange R 《Journal of the American Chemical Society》2008,130(41):13580-13588
Tryptophan synthase is an alpha2beta2 multienzyme complex that exhibits coupling of the alpha- and beta-subunit reactions by tightly controlled allosteric interactions. A wide range of parameters can affect the allosteric interactions, including monovalent cations, pH, alpha-site and beta-site ligands, temperature, and pressure. Rapid changes in hydrostatic pressure (P-jump) and temperature (T-jump) were used to examine the effects of pressure and temperature on the rates of the interconversion of external aldimine and aminoacrylate intermediates in the Tryptophan synthase-L-Ser complex. The intense fluorescence emission of the Tryptophan synthase L-Ser external aldimine complex at 495 nm, with 420 nm excitation, provides a probe of the conformational state of Trp synthase. P-jump measurements allowed the determination of rate constants for the reactions in the presence of Na(+), Na(+) with benzimidazole (BZI), and NH4(+). The data require a compressibility term, beta(o)(double dagger), to obtain good fits, especially for the NH4(+) and BZI/Na(+) data. The compressibility changes are consistent with changes in solvation in the transition state. The transition state for the relaxation is more similar in volume to the closed aminoacrylate complex in the presence of Na(+), while it is more similar to the open external aldimine in the presence of NH4(+). Differences between the relaxations for positive and negative P-jumps may arise from changing relative populations of microstates with pressure. T-jump experiments of the Na(+) form of the tryptophan synthase-L-Ser complex show large changes in rate and amplitude over the temperature range from 7 to 45 degrees C. The Arrhenius plots show strong curvature, and hence require a heat capacity term, DeltaC(p)(double dagger), to obtain good fits. The values of DeltaC(p)(double dagger) are very large and negative (-3.6 to -4.4 kJ mol(-1) K(-1)). These changes are also consistent with large changes in solvation in the transition state for interconversion of external aldimine and aminoacrylate intermediates in the Tryptophan synthase-L-Ser complex. 相似文献