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961.
Akari Narayama Sosa Israel González Alejandro Trejo Álvaro Miranda Fernando Salazar Miguel Cruz-Irisson 《Journal of computational chemistry》2020,41(31):2653-2662
Recently, the need of improvement of energy storage has led to the development of Lithium batteries with porous materials as electrodes. Porous Germanium (pGe) has shown promise for the development of new generation Li-ion batteries due to its excellent electronic, and chemical properties, however, the effect of lithium in its properties has not been studied extensively. In this contribution, the effect of surface and interstitial Li on the electronic properties of pGe was studied using a first-principles density functional theory scheme. The porous structures were modeled by removing columns of atoms in the [001] direction and the surface dangling bonds were passivated with H atoms, and then replaced with Li atoms. Also, the effect of a single interstitial Li in the Ge was analyzed. The transition state and the diffusion barrier of the Li in the Ge structure were studied using a quadratic synchronous transit scheme. 相似文献
962.
Darío M. González Nicole B. Cruz Loreto A. Hernández Jocelyn Oyarce Rosario Benavente Carolina Manzur 《Journal of polymer science. Part A, Polymer chemistry》2020,58(4):557-567
Two Bis-β-diketonate zinc (II) complexes were synthesized using 1-(thiophen-2-yl)butane-1,3-dione and 1-(thiophen-2-yl)-3-(thiophen-3-yl)propane-1,3-dione as ligands. By electropolymerization of their thiophenyl groups, the metallopolymers deposited on FTO electrodes were obtained. The main objective was to study the reactivity of these compounds as ROP catalysts for PLA synthesis, using directly the zinc complexes (homogeneous catalysis) and also the modified electrodes with metallopolymers (heterogeneous catalysis). The homogeneous catalysis studies allowed the optimization of the polymerization conditions, such as reaction time, catalyst concentration, and the use of benzyl alcohol as cocatalyst, as well as their influence on the conversion rate, average molecular weight and polydispersity of PLA, using rac-LA and L-LA as monomers. Also, the effect on tacticity and thermal properties were discussed. Finally, the ROP studies using immersed modified electrodes in the polymerization medium were carried out under optimized experimental conditions. These tests were positive for one of the studied compounds, reaching conversions of up to 67%. © 2020 Wiley Periodicals, Inc. J. Polym. Sci. 2020 , 58, 557–567 相似文献
963.
Kemel Arafet Florenci V. González Vicent Moliner 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(9):2002-2012
In this work a computational study of the mechanism of inhibition of cruzain, rhodesain, and cathepsin L cysteine proteases by the dipeptidyl nitroalkene Cbz-Phe-Ala-CH=CH-NO2 has been carried out by means of molecular dynamics simulations with hybrid QM/MM potentials. The free-energy surfaces confirmed that the inhibition takes place by the formation of a covalent bond between the protein and the β-carbon atom of the inhibitor. According to the results, the tested inhibitor should be a much more efficient inhibitor of cruzain than of rhodesain, and little activity would be expected against cathepsin L, in total correspondence with the available experimental data. The origin of these differences may lie in the different stabilizing electrostatic interactions established between the inhibitor and the residues of the active site and S2 pocket of these enzymes. These results may be useful for the rational design of new dipeptidyl nitroalkenes with higher and more selective inhibitory activity against cysteine proteases. 相似文献
964.
Francesco Talotta Martial Boggio-Pasqua Prof. Dr. Leticia González 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(50):11522-11528
The design of photoswitchable transition metal complexes with tailored properties is one of the most important challenges in chemistry. Studies explaining the underlying mechanisms are, however, scarce. Herein, the early relaxation dynamics towards NO photoisomerization in trans-[RuCl(NO)(py)4]2+ is elucidated by means of non-adiabatic dynamics, which provided time-resolved information and branching ratios. Three deactivation mechanisms (I, II, III) in the ratio 3:2:4 were identified. Pathways I and III involve ultrafast intersystem crossing and internal conversion, whereas pathway II involves only internal conversion. 相似文献
965.
966.
Alejandro S. González-Martín Gisela Hernandes-Gomes 《Research in Mathematics Education》2020,22(1):67-86
ABSTRACTIn this paper, we examine how differences in the academic and professional backgrounds of engineering teachers shape their personal relationship to the use of mathematics in engineering practices, and whether these differences affect some of their practices. The analyses herein are based on an institutional perspective and employ Chevallard's anthropological theory of the didactic (ATD). We interviewed two teachers in an engineering programme to identify specific elements of their practice that could be attributable to the mobilisation of knowledge and skills derived from their distinct academic backgrounds and experience. The results indicate that the teachers mobilise different tasks, techniques, and technologies in many of their practices, and that they take different approaches to using mathematics and applying rigour. 相似文献
967.
Dr. Luciana Cicco Prof. Antonio Salomone Dr. Paola Vitale Dr. Nicolás Ríos-Lombardía Dr. Javier González-Sabín Prof. Joaquín García-Álvarez Dr. Filippo M. Perna Prof. Vito Capriati 《ChemSusChem》2020,13(14):3583-3588
Highly polarized organometallic compounds of s-block elements are added smoothly to chiral N-tert-butanesulfinyl imines in the biodegradable d -sorbitol/choline chloride eutectic mixture, thereby granting access to enantioenriched primary amines after quantitatively removing the sulfinyl group. The practicality of the method is further highlighted by proceeding at ambient temperature and under air, with very short reaction times (2 min), enabling the preparation of diastereoisomeric sulfinamides in very good yields (74–98 %) and with a broad substrate scope, and the possibility of scaling up the process. The method is demonstrated in the asymmetric syntheses of both the chiral amine side-chain of (R,R)-Formoterol (96 % ee) and the pharmaceutically relevant (R)-Cinacalcet (98 % ee). 相似文献
968.
Eveliina Mäkelä José Luis González Escobedo Jouni Neuvonen Dr. Jouko Lahtinen Dr. Marina Lindblad Prof. Ulla Lassi Dr. Reetta Karinen Prof. Riikka L. Puurunen 《ChemCatChem》2020,12(16):4090-4104
Pyrolysis and liquefaction biocrudes obtained from lignocellulose are rich in phenolic compounds that can be converted to renewable aromatics. In this study, Pt catalysts on reducible metal oxide supports (Nb2O5, TiO2), along with irreducible ZrO2 as a reference, were investigated in the liquid-phase hydrodeoxygenation (HDO) of 4-propylphenol (350 °C, 20 bar H2, organic solvent). The most active catalyst was Pt/Nb2O5, which led to the molar propylbenzene selectivity of 77 %, and a yield of 75 % (98 % conversion). Reducible metal oxide supports provided an increased activity and selectivity to the aromatic product compared to ZrO2, and the obtained results are among the best reported in liquid-phase. The reusability of the spent catalysts was also studied. The spent Pt/Nb2O5 catalyst provided the lowest conversion, while the product distribution of the spent Pt/ZrO2 catalyst changed towards oxygenates. The results highlight the potential of pyrolysis or liquefaction biocrudes as a source of aromatic chemicals. 相似文献
969.
970.
Karen Hernández-Vidales Edgar Guevara Vanesa Olivares-Illana Francisco Javier González 《Journal of Raman spectroscopy : JRS》2019,50(10):1388-1394
To improve the early and reliable detection of cancer novel methods for the identification of associated biomarkers can suppose a big advantage over most of the techniques nowadays used for diagnosis because these techniques generally have the disadvantages of being laborious, invasive, and dependent on the physician's experience. The cancer biomarker wild-type p53 protein is naturally present in the human body and activated when cellular damage is detected. Mutations in p53 are related to the presence of tumors. In this work, Raman spectra of wild-type and mutant p53 were obtained. The spectra were analyzed by multivariate methods. Principal component analysis and support vector machine algorithms showed that it is possible to discriminate between the wild and mutant types of this biomarker with an accuracy of 94%. An estimation of the limit of the detection of the wild-type p53 protein by means of Raman spectroscopy was performed by partial least squares regression, reaching that it is possible to detect concentration as low as 0.946 μM without additional reagents. This proof-of-concept test shows that it is possible to detect and differentiate among types of p53 and represent the basis for an advanced study where a mechanism of signal amplification can be implemented. Raman spectroscopy in conjunction with multivariate mathematical techniques is projected as a complete tool capable of identifying biomarkers in a noninvasive, simple, and economical way, eliminating the subjective interpretation of the results, and therefore contributing to objective and more reliable diagnoses. 相似文献