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991.
The operating properties of different-type Brownian photomotors have been compared in relation to the symmetry interplay between their moving (particle/molecule) and immovable (substrate) units. As found, essentially different symmetry constraints and hence different motor behavior are characteristic of molecules if their electron density redistribution on excitation involves only odd-order or only even-order multipole moments. The two respective types of molecules give rise to dipole and quadrupole photomotors. Purely dipole photomotors can operate only on substrates with symmetric charge distribution and their ensemble with random molecular orientations undergoes equidirectional diffusion rather than directed motion. Contrary to this, purely quadrupole photomotors need substrates with antisymmetric charge distribution for directed motion to occur and they can move directionally in an ensemble. Also, quadrupole photomotors provide much smaller velocities of directed motion than their dipole counterparts (as a result of the much weaker interaction of quadrupoles than dipoles with an electric field). The generic distinctions between the two photomotor types are exemplified by donor-acceptor-substituted stilbenoids (dipole molecules) and symmetric squaraines (quadrupole molecules). The model used affords the rational design of photomotors by the selection of promising moving molecules and by the continuous wide-range tuning of charge-distribution symmetry in substrates. 相似文献
992.
Dr. Zheng Zhou Matthew Pennachio Dr. Zheng Wei Maxi L. Heldner Prof. Dr. Marina A. Petrukhina Dr. Tobias A. Schaub 《European journal of organic chemistry》2023,26(14):e202300168
A small macrocycle comprising ether-bridged naphthyl units was prepared in a two-step synthesis. Single-crystal X-ray diffraction of two polymorphs are reported, one of which showed multiple C−H⋅⋅⋅πnaphthyl interactions of a solvent molecule in the cavity of the macrocycle. Chemical reduction led to C−O bond cleavages accompanied by a Z/E isomerization. The resulting twofold negatively charged (E)-1,2-bis(2-naphthyl)ethylene fragment was isolated as its potassium salts. Electronic characterization revealed a singlet ground state, and a marked distortion of the central ethylene unit was observed upon electron uptake. 相似文献
993.
Dr. Craig P. Yu Akito Yamamoto Dr. Shohei Kumagai Prof. Jun Takeya Prof. Toshihiro Okamoto 《Angewandte Chemie (International ed. in English)》2023,62(4):e202206417
Synthetically versatile electron-deficient π-electron systems are urgently needed for organic electronics, yet their design and synthesis are challenging due to the low reactivity from large electron affinities. In this work, we report a benzo[de]isoquinolino[1,8-gh]quinoline diamide (BQQDA) π-electron system. The electron-rich condensed amide as opposed to the generally-employed imide provides a suitable electronic feature for chemical versatility to tailor the BQQDA π-electron system for various electronic applications. We demonstrate an effective synthetic method to furnish the target BQQDA parent structure, and highly selective functionalization can be performed on bay positions of the π-skeleton. In addition, thionation of BQQDA can be accomplished under mild conditions. Fine-tuning of fundamental properties and supramolecular packing motifs are achieved via chemical modifications, and the cyanated BQQDA organic semiconductor demonstrates a high air-stable electron-carrier mobility. 相似文献
994.
Maslova MV Rusanova D Naydenov V Antzutkin ON Gerasimova LG 《Inorganic chemistry》2008,47(23):11351-11360
Amorphous titanium hydroxyphosphate with formula Ti(OH)(1.36)(HPO(4))(1.32).2.3H(2)O and a new silica-modified titanium hydroxyphosphate with a general formula Ti(OH)(2x)(HPO(4))(2-x).ySiO(2).nH(2)O are synthesized and characterized using IR, TG, XRD, SEM, solid-state NMR, and BET techniques. It is concluded that SiO(2) is evenly distributed within the titanium phosphate (TiP) agglomerates and that neither the separate silica phase nor the titanium silicates are formed during the synthesis of silica-modified titanium hydroxyphosphate. Correlations between the texture, ion-exchange properties of the amorphous titanium hydroxyphosphate, and the amount of SiO(2) present within the TiP matrix are established. Sorption properties of silica-modified titanium hydroxyphosphate toward Cs(+) and Sr(2+) are studied in a series of samples with an increasing amount of silica, at different pH, and in NaCl solutions with a varying ionic strength. It is found that sorption of Cs(+) does not depend practically on the amount of SiO(2) present, whereas the Sr(2+) uptake drastically decreases with an increase of silica amount. The effects of pH and of the electrolyte concentration on the sorption behavior of titanium phosphate are discussed in terms of ionic hydration shell and titanium phosphate structural specificity. The kinetics of sorption processes is also investigated, and the diffusion coefficients for cesium and strontium are obtained. 相似文献
995.
Vladimir O. Gelmboldt Larisa V. Koroeva Marina S. Fonari Mark M. Botoshansky 《Journal of fluorine chemistry》2008,129(7):632-636
The preparation and characterization of three isomeric carboxypyridinium and carboxyquinolinium hexafluorosilicate salts is described. The salts of the general formulas (LH)2[SiF6] (I-III, L = 2-carboxypyridine, 3-carboxypyridine, 4-carboxypyridine) and (LH)2[SiF6]·2H2O (IV, L = 2-carboxyquinoline) were prepared from the protonation reaction of the corresponding pyridine carbonic acid by the fluorosilicic acid. The compounds were characterized by IR, mass-spectrometry, thermogravimetric analysis, solubility data, and in the case of III by X-ray crystallography. The relationship between the salts solubility and the H-bonding system was analysed. 相似文献
996.
Alexander S. Filatov Marina A. Petrukhina 《Journal of organometallic chemistry》2008,693(8-9):1590-1596
The reactivity of bowl-shaped mono-bromocorannulene (C20H9Br) has been examined and compared with that of corannulene (C20H10). Although bromination of corannulene was shown to flatten the bowl and change its electronic properties, it has not affected the outcome of coordination reactions toward the avid Lewis acidic [Rh2(O2CCF3)4] complex. Two new products have the same composition [{Rh2(O2CCF3)4}m · (C20H9Br)n] where m:n = 1:1 (1) and 3:2 (2), as the corresponding corannulene-based analogs. The X-ray diffraction studies of 1 and 2 revealed 1D chain and 2D layered structures built on η2-coordination of rhodium(II) to rim carbon sites of the C20H9Br-bowl, similar to those of C20H10. While no essential difference is found in 2D structures, the local coordination environments of the [Rh2(O2CCF3)4] unit differ in their 1D complexes. 相似文献
997.
Alexander Vladimirovich Ivanov Edward Danielevich Virus Ksenya Alexandrovna Nikiforova Nicolai Evgenevich Kushlinskii Boris Petrovich Luzyanin Marina Yurievna Maksimova Mikhail Aleksanrovich Piradov Aslan Amirkhanovich Kubatiev 《Electrophoresis》2016,37(20):2663-2669
An approach that allows direct analysis of the ratio of S‐adenosylmethionine (SAM) and S‐adenosylhomocysteine (SAH) by using CE is presented. The analytes were extracted on phenylboronic acid phase and eluted with 100 mmol/L HCl. CE separation of the analytes took place in the transient isotachophoresis mode with addition of NaCl and meglumine to the samples. The sensitivity (S/N = 3) and quantification limit (S/N = 10) of the method were 0.07 and 0.2 μmol/L, respectively, using a silica capillary with 50 μm internal diameter and 30.5 cm total length. The BGE was 0.02 mol/L Tris with 1 mol/L HCOOH (pH 2.2), and the separation voltage was 15–17 kV. Accuracy of SAM and SAH analysis in urine was 96 and 105%, respectively; interday precision for the SAM/SAH ratio was within 6%. The theoretical plate number exceeded a million. Total analysis time was 8.5 min. 相似文献
998.
Marina S. Vasilyeva Vladimir S. Rudnev Antonina S. Lapina Viktoriia I. Plyusnina Galina I. Marinina 《International journal of environmental analytical chemistry》2016,96(12):1128-1144
Ti/TiO2 indicator electrodes were prepared by plasma electrolytic oxidation (PEO) method in the tetraborate electrolyte and were used for potentiometric indication of chemical reactions of different types and for analysis of surface and industrial wastewaters on the example of potentiometric determination of alkalinity and chloride. The electrodes formed at current densities of 0.05, 0.1, 0.15 and 0.2 A/cm2 are different in composition, surface morphology and electroanalytical properties. The electrodes formed at a current density of 0.05 A/cm2 exhibit the highest pH-sensitivity and generate the highest analytical signal at the equivalence point in the acid–base and precipitation titrations. The maximum analytical signal at the equivalence point, exceeding in magnitude the analytical signal, obtained by classical Pt electrode in oxidation–reduction and complexometric titrations generates PEO layers formed at a current density of 0.05 A/cm2 and a platinum-modified nanoparticles. The results of the potentiometric titration of the surface and technogenic waters using as indicator Ti/TiO2 electrodes are comparable with the conventionally used glass electrode (to determine alkalinity) and Ag electrode (to the determine chloride) and the results of visual titration. The advantage of the obtained metal oxide systems is the ability to determine two hydrochemical parameters due to their multifunctionality and opportunity to work with a single electrode. In addition, these sensors offer some analytical characteristics such as sensitivity, good reproducibility, high mechanical stability and a simple preparation procedure. 相似文献
999.
Transfer of Electrophilic NH Using Convenient Sources of Ammonia: Direct Synthesis of NH Sulfoximines from Sulfoxides 下载免费PDF全文
Marina Zenzola Robert Doran Dr. Leonardo Degennaro Prof. Dr. Renzo Luisi Dr. James A. Bull 《Angewandte Chemie (International ed. in English)》2016,55(25):7203-7207
A new system for NH transfer is developed for the preparation of sulfoximines, which are emerging as valuable motifs for drug discovery. The protocol employs readily available sources of nitrogen without the requirement for either preactivation or for metal catalysts. Mixing ammonium salts with diacetoxyiodobenzene directly converts sulfoxides into sulfoximines. This report describes the first example of using of ammonia sources with diacetoxyiodobenzene to generate an electrophilic nitrogen center. Control and mechanistic studies suggest a short‐lived electrophilic intermediate, which is likely to be PhINH or PhIN+. 相似文献