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101.
Trifluoroethanol (TFE)-induced conformational changes in dynorphin A (1-13) were investigated using charge-state distribution (CSD) and hydrogen-deuterium exchange (HDX), combined with electrospray ionization (ESI) mass spectrometry (MS). Individual amino acids involved in secondary structural elements were identified by collision-induced dissociation-tandem mass spectrometry (MS/MS). It was observed that dynorphin A (1-13) largely exists in an unfolded conformation and a folded structure in increasing concentrations of TFE. In 50% TFE, it forms an alpha-helix that encompasses residues 1-9 and remains flexible from residues 10 to 13. 相似文献
102.
In this paper we prove an inverted version of A. J. Schwenk's result, which in turn is related to Ulam's reconstruction conjecture. Instead of deleting vertices from an undirected graphG, we add a new vertexv and join it to all other vertices ofG to get a perturbed graphG+v. We derive an expression for the characteristic polynomial of the perturbed graphG+v in terms of the characteristic polynomial of the original graphG. We then show the extent to which the characteristic polynomials of the perturbed graphs can be used in determining whether two graphs are non-isomorphic.This work was supported by the U.S. Army Research Office under Grant DAAG29-82-K-0107. 相似文献
103.
104.
We have measured excess molar volumes VE
m of binary mixtures of triethylene glycol monoethyl ether with methanol, ethanol, 1-propanol, 1-pentanol, and 1-hexanol over the full range of compositions at 25°C. The measurements were carried out with a continuous-dilution dilatometer. The excess molar volumes VE
m are negative over the entire range of composition for the systems triethylene glycol monoethyl ether + methanol, + ethanol, and + 1-propanol and positive for the remaining systems, triethylene glycol monoethyl ether + 1-pentanol, and + 1-hexanol. The excess VE
m increases in the positive direction with increasing chain length of the n-alcohol. The measured excess volumes have been compared to our previous published data with an effort to assess the effects of replacing methyl by ethyl groups and of inserting oxyethylene groups. The results have been used to estimate the excess partial molar volumes VE
m,i of the components. The behavior of VE
m and VE
m,i with composition and the number of carbon atoms in the alcohol molecule is discussed. 相似文献
105.
Cobalt bis(oxalato)nickelate pentahydrate, Co[Ni(C2O4)2]5H2O and cadmium bis(oxalato)nickelate tetrahydrate, Cd[Ni(C2O4)2]4H2O have been synthesized and characterized by elemental analysis, reflectance and IR spectral studies. Thermal decomposition
studies (TG, DTG and DTA ) in air showed that both the compound of cobalt and cadmium produced the oxide, MNiOx (x=3 for M=Co; x=2 for M=Cd ) at 325 and 360°C respectively. DSC studies in nitrogen attributed only the mixture of both the metal at the end.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
106.
A simple analytical two-body potential φ(r) = −Ar
−n + B exp(−pr
m) is considered for P-V calculations in bcc metals using Born stability criteria. It is shown that the stability of bcc metals
can be expressed uniquely as a function of a parameter q (discussed in the text). The P-V calculations are done in ten bcc metals. The calculations are compared with the experimental
data of shock-wave measurements and also with other potential available. It is found out that the present potential is better
than the other two-body potentials in case of bcc metals. Further, the calculations done for TOEC and the first pressure derivative
of SOEC are found in good agreement with the reported results. 相似文献
107.
This paper proposes a new kinetic-theory-based high-resolution scheme for the Euler equations of gas dynamics. The scheme uses the well-known connection that the Euler equations are suitable moments of the collisionless Boltzmann equation of kinetic theory. The collisionless Boltzmann equation is discretized using Sweby's flux-limited method and the moment of this Boltzmann level formulation gives a Euler level scheme. It is demonstrated how conventional limiters and an extremum-preserving limiter can be adapted for use in the scheme to achieve a desired effect. A simple total variation diminishing criteria relaxing parameter results in improving the resolution of the discontinuities in a significant way. A 1D scheme is formulated first and an extension to 2D on Cartesian meshes is carried out next. Accuracy analysis suggests that the scheme achieves between first- and second-order accuracy as is expected for any second-order flux-limited method. The simplicity and the explicit form of the conservative numerical fluxes add to the efficiency of the scheme. Several standard 1D and 2D test problems are solved to demonstrate the robustness and accuracy. 相似文献
108.
A Computational and Experimental Study of Thieno[3,4‐b]thiophene as a Proaromatic π‐Bridge in Dye‐Sensitized Solar Cells 下载免费PDF全文
George A. Puneky Dr. Amala Dass Dr. Shaik M. Zakeeruddin Prof. Mohammad Khaja Nazeeruddin Prof. Michael Grätzel Prof. Gregory S. Tschumper Prof. Jared H. Delcamp 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(2):694-703
Four D ‐π‐A dyes (D=donor, A=accpetor) based on a 3,4‐thienothiophene π‐bridge were synthesized for use in dye‐sensitized solar cells (DSCs). The proaromatic building block 3,4‐thienothiophene is incorporated to stabilize dye excited‐state oxidation potentials. This lowering of the excited‐state energy levels allows for deeper absorption into the NIR region with relatively low molecular weight dyes. The influence of proaromatic functionality is probed through a computational analysis of optimized bond lengths and nucleus independent chemical shifts (NICS) for both the ground‐ and excited‐ states. To avoid a necessary lowering of the TiO2 semiconductor conduction band (CB) to promote efficient dye–TiO2 electron injection, strong donor functionalities based on triaryl‐ and diarylamines are employed in the dye designs to raise both the ground‐ and excited‐state oxidation potentials of the dyes. Solubility, aggregation, and TiO2 surface protection are addressed by examining an ethylhexyl alkyl chain in comparison to a simple ethyl chain on the 3,4‐thienothiophene bridge. Power conversion efficiencies of up to 7.8 % are observed. 相似文献
109.
The charge-transfer complex formed between an amine and carbon tetrachloride can initiate the polymerization of vinyl monomers in a nonaqueous solvent such as dimethylsulfoxide. Here we use cyclopentylamine (CPA) and heptylamine (HA) as the donor compounds for charge-transfer initiation of the polymerization of methl methacrylate (MMA). The rate of polymerization Rp = k[MMA]1 [amine]0.5 [CCl4]0.5 when [CCl4] [amine] ≤ 1; when [CCl4] [amine] < 1, Rp becomes independent of [CCl4] and Rp = k[MMA]1.5 [amine]0.5. The average constant at 60°C for the polymerization of MMA in terms of monomer were (1.66 ± 0.03) × 10?5 and (1.46 ± 0.04) × 10?5 s?1 with CPA and HA, respectively, when [CCl4] [amine] ≤ 1, and (1.16 ± 0.04) × 10?5 and (1.39 ± 0.08) × 10?1 L/mol·s when [CCl4]/[amine] < 1. 相似文献
110.
The dimethyl phenyl phosphine (DMPP) initiated polymerization of methyl methacrylate (MMA) in dimethylsulfoxide was studied. Polymerization of MMA in this system required the presence of transition metal ions like Fe3+ or Cu2+. Kinetic studies showed that the propagation was free radical in nature. An interaction between DMPP and MMA was detected spectrophotometrically. A proposed mechanism involves a transition metal ion-activated dipole interaction between the carbonyl oxygen and the phosphorus atom with the ultimate formation of a methyl methacrylate type of free radical. 相似文献