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161.
H. Khalifa A. M. Amin Farouk A. Osman 《Fresenius' Journal of Analytical Chemistry》1960,172(3):167-175
Summary The acid-base properties of Fast Grey R. A. have been studied with reference to the mode of chelation of the dye with different valent metals. The pK values of 3.83, 10.53 and 10.70 corresponding to the three steps of ionization of the free acid were evaluated by the aid of the relation between log [acid]/[salt] and pH values obtained during the course of the potentiometric titration of the free acid with a free base. 相似文献
162.
A. Khatir Sam Mustafa M. Osman F. A. El-Khangi 《Journal of Radioanalytical and Nuclear Chemistry》1998,231(1-2):21-23
The principal objective pursued in this study is to establish the base-line data on protein content and on the status of elemental
composition in human milk from Sudanese subjects. The protein content was derived by multiplying the nitrogen content by a
factor 6.25. The nitrogen was determined using a 14 MeV neutron generator. The median values for crude protein and the total
dry matter found in this study were 1.23% (volume) and 104 g/l, respectively. Some minor and trace elements of biological
significance namely, Cl, K, Ca, Mn, Fe, Cu, Zn, Cr, Co and Mo were determined using energy dispersive X-ray fluorescence spectrometry.
The results obtained show good compatibility with the data reported by the WHO on elemental composition of human milk from
different geographical regions. 相似文献
163.
MUHAMMAD Nadeem Arshad HASSAN M.Faidallah ABDULLAH M.Asiri OSMAN I.Osman FAISAL M.S.Aqlan 《结构化学》2019,(3)
Pyridinone derivatives are of great interest in medicinal chemistry where they were found to be potent to various diseases. Their metal complexes added more value to their applications. Here, we have synthesized two 2-pyridinone derivatives(3-cyano-4-(4-hydroxy-3-methoxyphenyl)-6-phenyl-2(1 H)-pyridinone and 3-cyano-4-chlorophenyl-6-(4-tolyl)-2(1 H)-pyridinone) using one-pot multicomponent system. They were well characterized using spectroscopic techniques like nuclear magnetic resonance(NMR-1 H 13 C), Fourier transform infrared(FT-IR) and UV/Vis spectroscopy. The final structures were determined using single-crystal X-ray diffraction technique which helps us to determine their geometries. Density functional theory(DFT) and time-dependent density functional theory(TD-DFT) with suitable basis-sets of calculations have correctly simulated these spectroscopic parameters. The intramolecular charge transfer(ICT) of both substrates has been discussed using natural bond orbital(NBO) technique. Molecular electrostatic potential(MEP) surfaces showed their reactive locations for intermolecular charge transfer. Compared to p-nitroaniline(pNA), both substrates were shown to have substantial molecular hyperpolarizability. 相似文献
164.
165.
166.
Samir M. Osman Ahmed M. Abdel‐Megied Mohammed H. Zain Eldain Simimole Haleema Chithra Gopinath Sarojini Amma Sumalekshmy Hassan Y. Aboul‐Enein 《Biomedical chromatography : BMC》2019,33(11)
The commercial value of cashew nut shell liquid (CNSL) has become a cornerstone of the agrowaste industry. It is the by‐product of the cashew industry and has an 1/8 inch thickness of soft honeycomb structure. CNSL contains phenolic lipids with aliphatic chains such as anacardic acid, cardanol, cardol and methyl cardol, and their derivatives. The developed GC–MS method is rapid, accurate and selective using a selected derivatizing reagent, namely N‐methyl‐N‐(trimethylsilyl)‐trifluoroacetamide that was previously diluted 1:1% with anhydrous pyridine. The proposed GC–MS method was applied for the analysis of different CNSL samples. The results showed that all classes of CNSL compounds were detected. The four alkyl phenols were detected with their different alkyl sidechains without any interference. This method is also specified for the detection of fatty acids of saturated and unsaturated chains. Silylation did not cause any alteration in the chemical structure of CNSL compounds regardless of esterification action. Silylation is considered a safe derivatizing agent compatible with GC chromatography and specific for all volatile and nonvolatile polar and nonpolar CNSL compounds that could be detected in CNSL samples. 相似文献
167.
168.
Raoul R. Nigmatulin Alexander P. Alekhin Dumitru Baleanu Erdal Dinç Zafer Üstündağ Haslet Ekşi Ali Osman Solak 《Electroanalysis》2010,22(4):419-426
The effect of the potential cycles on the reflective IR signals of nitro‐groups in nanofilms was studied for the statistical characterization of nitrobenzene (NB) and nitroazobenzene (NAB)‐modified glassy carbon (GC) surfaces. Both NB and NAB nanofilms were obtained by the electrochemical reduction of the diazonium tetrafluoroborate salts in acetonitrile using cyclic voltammetry (CV). The modified surfaces were denoted as GC‐(NB)n and GC‐(NAB)n, respectively, where n indicates the number of CV cycles performed during modification. Reflective IR signals of the normalized NB and NAB nanofilms and GC were used for the quantitative evaluation of the effect of the potential cycles on the reflective IR signals of nitro‐groups in nanofilms. The detection and quantitative ‘reading’ of the influence of number of CV cycles were realized in the frame of a new error controllable approach that was applied for analysis of all available set of data. This approach includes in itself the following basic steps: (a) the procedure of the division (normalization) on the GC spectra, (b) the comparison of the smoothed spectra for their statistical proximity in the frame of the statistics of the fractional moments, (c) extraction of possible calibration parameters for possible calibration of the normalized spectra with respect to the number of CV cycles. These three basic steps are becoming effective for detection of the influence of some external factors. In our case it is important to detect the influence of the factor n characterizing CV cycles. 相似文献
169.
Farahiyah Mustafa Norfarariyanti Parimon Abdul Manaf Hashim Shaharin Fadzli Abd Rahman Abdul Rahim Abdul Rahman Mohd Nizam Osman 《Superlattices and Microstructures》2010
A Schottky diode was designed and fabricated on an n-AlGaAs/GaAs high electron mobility transistor (HEMT) structure for RF power detection. The processing steps used in the fabrication were the conventional steps used in standard GaAs processing. Current–voltage measurements showed that the devices had rectifying properties with a barrier height of 0.5289–0.5468 eV. The fabricated Schottky diodes detected RF signals well and their cut-off frequencies up to 20 GHz were estimated in direct injection experiments. To achieve a high cut-off frequency, a smaller Schottky contact area is required. The feasibility of direct integration with the planar dipole antenna via a coplanar waveguide transmission line without insertion of matching circuits was discussed. A higher cut-off frequency can also be achieved by reducing the length of the coplanar waveguide transmission line. These preliminary results represent a breakthrough as regards direct on-chip integration technology, towards the realization of a ubiquitous network society. 相似文献
170.
The conducting polymer electrolyte films consisting of polyacrylonitrile (PAN) as the host polymer, lithium triflate (LiCF3SO3) and sodium triflate (NaCF3SO3) as inorganic salts were prepared by the solution-cast technique. The pure PAN film was prepared as a reference. The ionic
conductivity for the films is characterized using impedance spectroscopy. The room temperature conductivity for the PAN + 26 wt.%
LiCF3SO3 film and the PAN + 24 wt.% NaCF3SO3 film is 3.04 × 10−4 S cm−1 and 7.13 × 10−4 S cm−1, respectively. XRD studies show that the complexation that has occurred in the PAN containing salt films and complexes formed
are amorphous. The FTIR spectra results confirmed the complexation has taken place between the salt and the polymer. These
results correspond with surface morphology images obtained from SEM analysis. The conductivity–temperature dependence of the
highest conducting film from PAN + LiCF3SO3 and PAN + NaCF3SO3 systems follows Arrhenius equation in the temperature range of 303 to 353 K. The PAN containing 24 wt.% LiCF3SO3 film has a higher ionic conductivity and lower activation energy compared to the PAN containing 26 wt.%LiCF3SO3 film. These results can be explained based on the Lewis acidity of the alkali ions, i.e., the interaction between Li+ ion and the nitrogen atom of PAN is stronger than that of Na+ ion. 相似文献