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121.
Solvent-free reactions were used for the synthesis of a series of imidazolium-based ionic salts: 3,3′-[pyridine-2,6-diylbis(methylene)]bis(1-R-1H-imidazol-3-ium)chloride; (R = methyl, ethyl, butyl, isobutyl, hexyl, and benzyl). A simple and effective filtration process was used to isolate all the products in high purity and with yields ?93% within a 24 h period. The highly pure ionic compounds which are precursors to N-heterocyclic carbene ligands used in catalysis were fully characterized as gray-white hygroscopic salts. 相似文献
122.
A simple method for the preparation of enantiopure furo[2,3-b]pyrroles, a rare class of concave bicyclic nitrogen and oxygen heterocycle, in promising yield has been developed. The 3-substituted pyrrolidinediones prepared from (2S,3S)-tetrahydro-3-hydroxy-5-oxo-2,3-furandicarboxylic acid (Garcinia acid) have been cyclized diastereo as well as enantioselectively to furo[2,3-b]pyrroles. The cyclization follows Baldwin’s rule. 相似文献
123.
I. A. Alnour H. Wagiran N. Ibrahim S. Hamzah B. S. Wee M. S. Elias 《Journal of Radioanalytical and Nuclear Chemistry》2014,299(1):177-186
This work aimed to study the capability of INAA absolute method in determining the elemental concentration of 238U and 232Th in the rock samples. The INAA absolute method was implemented in PUSPATI TRIGA Mark II research reactor, Malaysian Nuclear Agency (NM). The accuracy of INAA absolute method was performed by analyzing the IAEA certified reference material (CRM) Soil-7. The analytical results showed the deviations between experimental and certified values were mostly less than 10 % with Z-score in most cases less than 1. In general, the results of analysed CRM Soil-7 show a good agreement between certified and experimental results which mean that the INAA absolute method can be used accurately for elemental analysis of uranium and thorium in various types of samples. The concentration of 238U and 232Th ranged from 1.77 to 24.25 and 0.88 to 95.50 ppm respectively. The highest value of 238U and 232Th was recorded for granite rock sample G17 of 238U and sample G9 of 232Th, whereas the lower value was 1.77 ppm of 238U recorded in sandstone rock and 0.88 ppm of 232Th for gabbro. Moreover, a comparison of the 238U and 232Th results obtained by the INAA absolute method shows an acceptable level of consistency with those obtained by the INAA relative method. 相似文献
124.
Mohamed M. Ibrahim Gaber A.M. Mersal Nagi El-Shafai Mohamed M. Youssef Hanaa Shokry 《Comptes Rendus Chimie》2014,17(10):1013-1022
A dithiolate-containing a carbamate mononuclear cobalt(II) complex namely, [Co(Boc-S)2] (1), was obtained by the reaction of a methanolic solution of cobalt(II) nitrate hexahydrate with two equimolar amounts of the deprotonated form of tert-butyl N-(2-mercaptoethyl)carbamate (Boc-SH). The cobalt(II) complex (1) was characterized in the solid state and in solution by using FT–IR, Raman, UV–visible, and EI–mass spectroscopies, as well as thermal and X-ray diffraction studies. Spectral data showed that the carbamate (Boc-SH) acts as a mono-anionic bidentate ligand coordinating the cobalt(II) ion through two imine nitrogen and two deprotonated thiolate sulfur donor atoms in a distorted tetrahedral geometry. The thermoanalytical data evidence that the complex is stable up to 165 °C and undergoes complete decomposition, resulting in CoO. TEM imaging of the oxide residue shows its nano size clusters, suggesting that the complex (1) may be used as a precursor for nano-oxides. X-ray powder diffraction patterns evidence an isomorphism among the complex. The redox behavior of the cobalt(II) complex was also investigated by cyclic voltammetry. The reaction of the dithiolate cobalt(II) complex (1) with methyl iodide appears to occur intramolecularly with the cobalt-bound dithiolate, forming the cobalt(II)-bound dithioether complex [Co(Boc–SCH3)2]I2 (2), as a dication complex with a clean second-order reaction of 13.24 × 10−2 M−1·s−1. 相似文献
125.
Mohammed Safar Saeed Balci Esra Qadir Hussein Ahmed Qader Ibrahim Nazem Saydam Sinan Dagdelen Fethi 《Journal of Thermal Analysis and Calorimetry》2022,147(21):11705-11713
Journal of Thermal Analysis and Calorimetry - The influence of four different quantities of niobium (Nb) on some physical and chemical properties of Ni-Ti alloy was examined in this study.... 相似文献
126.
G. Yasin S. Ibraheem S. Ali M. Arif S. Ibrahim R. Iqbal A. Kumar M. Tabish M.A. Mushtaq A. Saad H. Xu W. Zhao 《Materials Today Chemistry》2022
Controllable tailoring of metal-free/carbon-based nanostructures tends an encouraging way to enhance the bifunctional activity of electrodes, but a great challenge owing to the sluggish kinetics of oxygen evolution reaction (OER) and hydrogen evolution reaction (HER). Herein, a facile tempted-defects assisted fractionation strategy is presented to synthesize N, S, and O tri-doped metal-free catalyst (DE-TDAP). Due to this effective tempted-defects and heteroatoms interlinking in DE-TDAP, it delivers the lowest overpotential toward both the OER (346 mV) and HER (154 mV) at 10 mA cm?2. Remarkably, the DE-TDAP-electrode carries only a cell voltage of 1.81 V at 10 mA cm?2 for overall water splitting and long-term stability. Considerably, the density functional theory (DFT) calculation exposes that the tailored-defects in tri-doped interlinking could enhance bifunctional catalytic performance devising from lower Gibbs free energy of OER/HER intermediates on active sites. This struggle henceforth provides a perceptive understanding of the synergetic principles of heteroatom-interlinking-tailoring nanostructures in water splitting. 相似文献
127.
Okonkwo Eric C. Wole-Osho Ifeoluwa Almanassra Ismail W. Abdullatif Yasser M. Al-Ansari Tareq 《Journal of Thermal Analysis and Calorimetry》2021,145(6):2817-2872
Journal of Thermal Analysis and Calorimetry - The field of nanofluids has received interesting attention since the concept of dispersing nanoscaled particles into a fluid was first introduced in... 相似文献
128.
Bruno Oyallon Marie Brachet-Botineau Cdric Log Thomas Robert Stphane Bach Sajida Ibrahim William Raoul Ccile Croix Pascal Berthelot Jean Guillon Noël Pinaud Fabrice Gouilleux Marie-Claude Viaud-Massuard Caroline Denevault-Sabourin 《Molecules (Basel, Switzerland)》2021,26(4)
Proviral integration site for Moloney murine leukemia virus (Pim)-1/2 kinase overexpression has been identified in a variety of hematologic (e.g., multiple myeloma or acute myeloid leukemia (AML)) and solid (e.g., colorectal carcinoma) tumors, playing a key role in cancer progression, metastasis, and drug resistance, and is linked to poor prognosis. These kinases are thus considered interesting targets in oncology. We report herein the design, synthesis, structure–activity relationships (SAR) and in vitro evaluations of new quinoxaline derivatives, acting as dual Pim1/2 inhibitors. Two lead compounds (5c and 5e) were then identified, as potent submicromolar Pim-1 and Pim-2 inhibitors. These molecules were also able to inhibit the growth of the two human cell lines, MV4-11 (AML) and HCT-116 (colorectal carcinoma), expressing high endogenous levels of Pim-1/2 kinases. 相似文献
129.
Mohammed Hamed Alqarni Ahmed Ibrahim Foudah Magdy Mohamed Muharram Haritium Budurian Nikolaos E. Labrou 《Molecules (Basel, Switzerland)》2021,26(5)
The reactive adenosine derivative, adenosine 5′-O-[S-(4-hydroxy-2,3-dioxobutyl)]-thiophosphate (AMPS-HDB), contains a dicarbonyl group linked to the purine nucleotide at a position equivalent to the pyrophosphate region of NAD+. AMPS-HDB was used as a chemical label towards Candida boidinii formate dehydrogenase (CbFDH). AMPS-HDB reacts covalently with CbFDH, leading to complete inactivation of the enzyme activity. The inactivation kinetics of CbFDH fit the Kitz and Wilson model for time-dependent, irreversible inhibition (KD = 0.66 ± 0.15 mM, first order maximum rate constant k3 = 0.198 ± 0.06 min−1). NAD+ and NADH protects CbFDH from inactivation by AMPS-HDB, showing the specificity of the reaction. Molecular modelling studies revealed Arg174 as a candidate residue able to be modified by the dicarbonyl group of AMPS-HDB. Arg174 is a strictly conserved residue among FDHs and is located at the Rossmann fold, the common mononucleotide-binding motif of dehydrogenases. Arg174 was replaced by Asn, using site-directed mutagenesis. The mutant enzyme CbFDHArg174Asn was showed to be resistant to inactivation by AMPS-HDB, confirming that the guanidinium group of Arg174 is the target for AMPS-HDB. The CbFDHArg174Asn mutant enzyme exhibited substantial reduced affinity for NAD+ and lower thermostability. The results of the study underline the pivotal and multifunctional role of Arg174 in catalysis, coenzyme binding and structural stability of CbFDH. 相似文献
130.
Iodice M Cusanno F Acha A Ambrozewicz P Aniol KA Baturin P Bertin PY Benaoum H Blomqvist KI Boeglin WU Breuer H Brindza P Bydzovský P Camsonne A Chang CC Chen JP Choi S Chudakov EA Cisbani E Colilli S Coman L Craver BJ De Cataldo G de Jager CW De Leo R Deur AP Ferdi C Feuerbach RJ Folts E Fratoni R Frullani S Garibaldi F Gayou O Giulani F Gomez J Gricia M Hansen JO Hayes D Higinbotham DW Holmstrom TK Hyde CE Ibrahim HF Jiang X Kaufman LJ Kino K Kross B Lagamba L LeRose JJ Lindgren RA 《Physical review letters》2007,99(5):052501
An experiment measuring electroproduction of hypernuclei has been performed in hall A at Jefferson Lab on a 12C target. In order to increase counting rates and provide unambiguous kaon identification two superconducting septum magnets and a ring imaging Cherenkov detector were added to the hall A standard equipment. An unprecedented energy resolution of less than 700 keV FWHM has been achieved. Thus, the observed (Lambda)(12)B spectrum shows for the first time identifiable strength in the core-excited region between the ground-state s-wave Lambda peak and the 11 MeV p-wave Lambda peak. 相似文献