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991.
992.
Dr. Paula Gómez‐Álvarez Prof. Sofia Calero 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(52):18705-18708
The separation of carbon dioxide from flue gas is essential for the reduction of greenhouse gas emissions. In adsorptive methods, the challenge lies in the choice of suitable porous materials. Among all zeolite topologies, a number of adsorbents with pore dimensions in the range of the guest molecules were identified to allow an excellent separation by diffusion, and MRE and AFO zeolite topologies appear to be the best candidates based on equilibrium adsorption. Also, it was found that the behavior of this gas mixture in DFT and APD zeolites differed from the normal behavior. 相似文献
993.
R. Y. Gerasimov G. N. Fadeev Y. V. Gerasimov E. A. Kondratova 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2016,90(9):1785-1788
Radio-wave emission spectra in the microwave region are registered for the first time for ordinary water (H2O), heavy water (D2O), and D2O with a low content of T2O. The obtained spectra are analyzed according to a special program using a hardware–software complex. Measurement results show that the proposed method allows us not only to determine differences between substances in terms of composition and concentration, but to determine the presence of heavy and superheavy hydrogen isotopes in ordinary water as well. 相似文献
994.
Thomas Özgün Dr. Klaus Bergander Dr. Lei Liu Dr. Constantin G. Daniliuc Prof. Dr. Stefan Grimme Dr. Gerald Kehr Prof. Dr. Gerhard Erker 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(34):11958-11961
The energy profile of a frustrated Lewis pair (FLP) dihydrogen splitting system was determined by a combined experimental kinetic and DFT study. A trimethylene‐bridged phosphane–borane FLP was converted into its endothermic H2‐cleavage product by sequential H+/H? addition. The system could be handled at low temperature, and the kinetics of the H2 elimination were determined to give a rate constant of kHH,exp(299 K)=(2.87±0.1)×10?4 s?1 in solution. The primary kinetic isotope effects were determined; for example, (kHH/kDD)exp=3.19. The system was accurately analyzed by DFT calculations. 相似文献
995.
996.
B. M. Rumyantsev S. B. Bibikov A. V. Bychkova V. G. Leontiev V. I. Berendyaev O. N. Sorokina A. L. Kovarskii 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2016,90(12):2426-2433
The conductivity of polymer composites with magnetic nanoparticles (MNP) containing magnetite and other MNP (Ni, Cu–Ni) in the layers and planar cells with Al electrodes is studied. For soluble polymers (polyvinylpyrrolidone and polyvinyl alcohol) containing 1–10 wt % of magnetite MNP, a substantial effect of MNP on surface conductivity is detected over a wide range (from 10–10 to 10–3 Ω–1). It is shown that the addition of magnetite MNP not only results in a considerable change in cell conductivity, but also leads to its partially irreversible variation (by an order of magnitude or more) via minor modifications of the experimental conditions (temperature, electric field). For high-resistance samples with low probabilities of conducting chain formation, temperature current peaks are observed upon moderate heating (up to 350 K). These peaks are similar to the maxima observed upon polymer electret thermodischarges when the charges are captured by the deep centers associated with separate MNP or MNP aggregates. The type and position of the maxima are determined by the characteristics of the polymer matrix. For polyvinylpyrrolidone composites, the maxima are observed some time after heating (the echo effect). With composites based on solventborne polymers (polyalkanesterimides, soluble polyimide) and Ni, Cu–Ni MNP, no change in film conductivity measured electrophotographically is observed, due to the formation of a dielectric coating formed by polymer macromolecules adsorbed on the MNP surface. An explanation based on the possible formation of magnetic aggregates of magnetite MNP and conducting chains is proposed. Magnetic aggregation IPM is proposed as one way of controlling cell conductivity. 相似文献
997.
DFT calculations with B3LYP and PBE0 functionals have been carried out to determine the structural parameters, vibrational frequencies, and quadrupole moments of double-decker heavy lanthanide phthalocyaninates Pc2Lu, (Pc2Lu)+, (Pc2Lu)–, Pc2Yb, (Pc2Yb)+, and (Pc2Yb)–. Free valence of the Pc moiety [0.5 in Pc2Lu and Pc2Yb; 1.0 in (Pc2Lu)+ and (Pc2Yb)+] is delocalized in small fractions over the carbon atoms. The Pc2Lu и Pc2Yb molecules have a high electron affinity (3.2 eV) and a low ionization potential (6.1–6.3 eV). Calculations predict formation of quadruple-decker supercomplex Yb(Pc2Lu)2 from two Pc2Lu molecules and an Yb atom via an exothermic process. The equilibrium structure of the molecules and ions can be characterized by D4d point symmetry group. 相似文献
998.
I. Yu. Dmitriev V. P. Ivanov N. V. Bobrova Z. F. Zoolshoev I. S. Kuryndin G. K. Elyashevich 《Russian Journal of Applied Chemistry》2016,89(11):1838-1845
A procedure was developed for preparing hybrid hydrogel specimens of preset configuration from cross-linked polyacrylic acid and polyvinyl alcohol. The specimens exhibit higher mechanical characteristics compared to hydrogels of cross-linked polyacrylic acid. Hydrogel specimens fabricated in the form of elastic rings demonstrate an electromechanical response, contraction on passing electric current through their cross section. This effect is more pronounced for the specimens swollen in a sodium sulfate solution than for those swollen in distilled water. The results obtained show that the hydrogels can be used as a linearly operating mechanical force generator (artificial muscle). 相似文献
999.
Wavelength selection framework for classifying food and pharmaceutical samples into multiple classes
M. Anzanello F. Fogliatto M. C. A. Marcelo D. Pozebon M. F. Ferro 《Journal of Chemometrics》2016,30(6):346-353
Near infrared (NIR) spectroscopy is an efficient, low‐cost analytical technique widely applied to identify the origin of food and pharmaceutical products. NIR spectra‐based classification strategies typically use thousands of equally spaced wavelengths as input information, some of which may not carry relevant information for product classification. When that is the case, the performance of predictive and exploratory multivariate techniques may be undermined by such noisy information. In this paper, we propose an iterative framework for selecting subsets of NIR wavelengths aimed at classifying samples into categories. For that matter, we integrate Principal Components Analysis (PCA) and three classification techniques: k‐Nearest Neighbor (KNN), Probabilistic Neural Network (PNN) and Linear Discriminant Analysis (LDA). PCA is first applied to NIR data, and a wavelength importance index is derived based on the PCA loadings. Samples are then categorized using the wavelength with the highest index and the classification accuracy is calculated; next, the wavelength with the second highest index is inserted into the dataset and a new classification is performed. This forward‐based iterative procedure is carried out until all original wavelengths are inserted into the dataset used for classification. The subset of wavelengths leading to the maximum accuracy is chosen as the recommended subset. Our propositions performed remarkably well when applied to four datasets related to food and pharmaceutical products. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
1000.
The Synthesis of B2(SIDip)2 and its Reactivity Between the Diboracumulenic and Diborynic Extremes 下载免费PDF全文
Julian Bhnke Holger Braunschweig Theresa Dellermann William C. Ewing Kai Hammond J. Oscar C. Jimenez‐Halla Thomas Kramer Jan Mies 《Angewandte Chemie (International ed. in English)》2015,54(46):13801-13805
A new compound with the formula L‐B2‐L wherein the stabilizing ligand (L) is 1,3‐bis[diisopropylphenyl]‐4,5‐dihydroimidazol‐2‐ylidene (SIDip) has been synthesized, isolated, and characterized. The π‐acidity of the SIDip ligand, intermediate between the relatively non‐acidic IDip (1,3‐bis[diisopropylphenyl]imidazol‐2‐ylidene) ligand and the much more highly acidic CAAC (1‐[2,6‐diisopropylphenyl]‐3,3,5,5‐tetramethylpyrrolidin‐2‐ylidene) ligand, gives rise to a compound with spectroscopic, electrochemical, and structural properties between those of L‐B2‐L compounds stabilized by CAAC and IDip. Reactions of all three L‐B2‐L compounds with CO demonstrate the differences caused by their respective ligands, as the π‐acidities of the CAAC and SIDip carbenes enabled the isolation of bis(boraketene) compounds (L(OC)B‐B(CO)L), which could not be isolated from reactions with B2(IDip)2. However, only B2(IDip)2 and B2(SIDip)2 could be converted into bicyclic bis(boralactone) compounds. 相似文献