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81.
This method computes tight lower and upper bounds for the renewal function. It is based on Riemann-Stieltjes integration, and provides bounds for solving certain renewal equations used in the study of availability. An error analysis is given for the numerical bounds when inter-renewal time distributions are sufficiently smooth. Three examples are explored that demonstrate the accuracy of these computed numerical bounds 相似文献
82.
In this paper we introduce a new type of difference operator Δ
m
n
for fixed m, n ∈ ℕ. We define the sequence spaces ℓ∞(Δ
m
n
), c(Δ
m
n
) and c
0(Δ
m
n
) and study some topological properties of these spaces. We obtain some inclusion relations involving these sequence spaces.
These notions generalize many earlier existing notions on difference sequence spaces.
相似文献
83.
84.
Long-chain N-alkyl-2-(phenylthio)acetohydrazides were synthesized via the reactions of 2-(phenylthio)acetohydrazide with long-straight-chain aldehydes and then reduction with sodium borohydride.
The reactions of long-straight-chain hydrazides with carbon disulfide in alkaline media give the corresponding carbodithioate
salts. Heating of potassium 2-alkanoylhydrazinecarbodithioates with phenacyl bromide do not yield cyclization and failed to
give the corresponding long-chain thiazolidine-2-thiones, but gave the corresponding 2-oxo-2-phenylethyl-2-alkanoylhydrazinecarbodithioates
via nucleophilic substitution reaction. In addition, the synthesized compounds were tested for their corrosion prevention capabilities
in acidic or in mineral oil media. 相似文献
85.
Ayhan Yavuz Genel Bahri Ülküseven İrfan Kızılcıklı 《Russian Journal of Inorganic Chemistry》2008,53(11):1747-1753
The thiosemicarbazone derivatives R1-C6H4-CH=N-N=(C-S-R2)-NH-R3 [R1 = H, OH; R2 = H, Ph; R3 = C2H5, C3H5] were prepared by a modified general method. The Pd(II) complexes of the thiosemicarbazone ligands LI–VI were isolated in the compositions [Pd(L)Cl2], [Pd(L)Cl] and [Pd(L)2]. The 1: 1 and 1: 2 metal complexes have non-ionic character, and the compounds were characterized by analytical data and infrared and proton resonance spectroscopy. The cis-trans and syn-anti isomers of the thiosemicarbazones were determined by means of 1H NMR, and the coordination behavior of the polydentate thiosemicarbazone ligands towards the palladium ion were discussed. 相似文献
86.
The α′-acetoxylation of enones and the α-acetoxylation of aromatic ketones were carried out with potassium permanganate and acetic acid, in which acetoxylation products were obtained in 74-96% yields. The same reaction was carried out with carboxylic acids other than acetic acid, which furnished corresponding acyloxy ketones with the same regioselectivity. For the first time, formyloxylation products were synthesized in a 61-85% yield by using formic acid. The potassium permanganate and acetic acid method was also used for aryl coupling reactions. The reaction of arylboronic acids and arylhydrazines in benzene with potassium permanganate and acetic acid in turn furnished biaryls in 85-96% yield. We have shown that potassium permanganate/carboxylic acid/organic solvent behaves as manganese(III) acetate. 相似文献
87.
Ceyhan T Yüksek M Yağlioğlu HG Salih B Erbil MK Elmali A Bekaroğlu O 《Dalton transactions (Cambridge, England : 2003)》2008,(18):2407-2413
In this study, the preparation of some novel metallophthalocyanine (MPcs) complexes substituted with octakis(mercaptopropylisobutyl-POSS) functional group was achieved. By the reaction of [1-(3-mercapto)propyl-3,5,7,9,11,13,15-isobutylpentacyclo[9.5.1.1(3,9).1(5,15).1(7,13)]octasiloxane 1 with 4,5-dichloro-1,2-dicyanobenzene 2 in THF as the solvent in the presence of K2CO3 as the base, the phthalonitrile derivative 3 was synthesized. Compound 3 reacted with CoCl2 x 6H2O in ethylene glycol to furnish a novel cobalt(II) phthalocyanine . The tetramerization of 3 with urea and CuCl in the absence of solvent gave the novel Cu(II) phthalocyanine 4; while with Zn(OAc)2 x 2H2O in dry DMF gave the novel zinc(ii) phthalocyanine 6. The structures of the target compounds were confirmed by elemental analysis, UV/VIS, IR, MALDI-TOF MS and 1H NMR spectra. Nonlinear absorptions of MPcs in chloroform solution were investigated by using Z-scan measurement technique with 4 ns pulses at 532 nm wavelength. While CuPc 5 showed very high nonlinear absorption, MPcs 4 and 6 did not show considerable nonlinear absorption. Investigations of optical limiting properties of 5 revealed that this material is a very good candidate for optical limiting applications. 相似文献
88.
Dr. Elif Akhuseyin Yildiz Dr. Ebru Yabaş Prof. Fazlı Sözmen Dr. Yasemin Bozkurt Dr. Ahmet Karatay Prof. Bahadir Boyacioglu Prof. Hüseyin Ünver Dr. Ayhan Elmali 《Chemphyschem》2023,24(5):e202200735
Borondipyrromethene (BODIPY) chromophores are composed of a functional-COOH group at meso position with or without a biphenyl ring, and their compounds with heavy iodine atoms at −2, −6 positions of the BODIPY indacene core were synthesized. The photophysical properties of the compounds were studied with steady-state absorption and fluorescence measurements. It was observed that the absorption band is significantly red-shifted, and fluorescence signals are quenched in the presence of iodine atoms. In addition to that, it was indicated that the biphenyl ring does not affect the spectral shifting in the absorption as well as fluorescence spectra. In an attempt to investigate the effect of π-expanded biphenyl moieties and heavy iodine atoms on charge transfer dynamics, femtosecond transient absorption spectroscopy measurements were carried out in the environment of the tetrahydrofuran (THF) solution. Based on the performed ultrafast pump-probe spectroscopy, BODIPY compounds with iodine atoms lead to intersystem crossing (ISC) and ISC rates were determined as 150 ps and 180 ps for iodine BODIPY compounds with and without π-expanded biphenyl moieties, respectively. According to the theoretical results, the charge transfer in the investigated compounds mostly appears to be intrinsic local excitations, corresponding to high photoluminescence efficiency. These experimental findings are useful for the design and study of the fundamental photochemistry of organic triplet photosensitizers. 相似文献
89.
Acyl phosphonates with alpha-halo ketones in the presence of bases at room temperature afford cis- and trans-epoxyphosphonates in good chemical yields and high selectivities using different bases. The diastereoselectivity of this reaction is easily controlled by changing the base. Changing the base from Cs2CO3 to DBU changed the diastereomeric ratio (trans/cis) from 3/2 to 9/1. Moreover, the treatment of the trans isomer with DBU showed a complete conversion to the corresponding cis isomer. 相似文献
90.
Gulay Algul Yusuf Ceylan Hacer Yumurtaci Aydogmus Ayhan Usta Biray Asik 《辐射效应与固体损伤》2016,171(5-6):451-460
1H-Benzo[b]pyrrole samples were irradiated in the air with gamma source at 0.969?kGy per hour at room temperature for 24, 48 and 72?h. After irradiation, electron spin resonance, thermogravimetry analysis (TGA) and differential thermal analysis (DTA) measurements were immediately carried out on the irradiated and unirradiated samples. The ESR measurements were performed between 320 and 400?K. ESR spectra were recorded from the samples irradiated for 48 and 72?h. The obtained spectra were observed to be dependent on temperature. Two radical-type centres were detected on the sample. Detected radiation-induced radicals were attributed to R-+?NH and R=?CC2H2. The g-values and hyperfine constants were calculated by means of the experimental spectra. It was also determined from TGA spectrum that both the unirradiated and irradiated samples were decomposed at one step with the rising temperature. Moreover, a theoretical study was presented. Success of the machine learning methods was tested. It was found that bagging techniques, which are widely used in the machine learning literature, could optimise prediction accuracy noticeably. 相似文献