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排序方式: 共有698条查询结果,搜索用时 46 毫秒
101.
102.
A. E. Bal’tser D. A. Zaitsev N. G. Zubritskaya T. V. Ivanova T. G. Babenko E. N. Barskova 《Russian Journal of Applied Chemistry》2016,89(9):1421-1426
Method for synthesis of bisphenols on a solid cation-exchange catalyst in the presence of hydrogen sulfide was optimized with respect to the main technological parameters. This method provides high yields of bisphenols obtained both on the basis of acetone and in the case of complex sterically hindered ketones: 9-fluorenone and dihydroisophorone. 相似文献
103.
104.
Balázs Frankó Karin Carlqvist Mats Galbe Gunnar Lidén Ola Wallberg 《Applied biochemistry and biotechnology》2018,184(2):599-615
Softwood bark contains a large amounts of extractives—i.e., soluble lipophilic (such as resin acids) and hydrophilic components (phenolic compounds, stilbenes). The effects of the partial removal of water-soluble extractives before acid-catalyzed steam pretreatment on enzymatic digestibility were assessed for two softwood barks—Norway spruce and Scots pine. A simple hot water extraction step removed more than half of the water-soluble extractives from the barks, which improved the enzymatic digestibility of both steam-pretreated materials. This effect was more pronounced for the spruce than the pine bark, as evidenced by the 30 and 11% glucose yield improvement, respectively, in the enzymatic digestibility. Furthermore, analysis of the chemical composition showed that the acid-insoluble lignin content of the pretreated materials decreased when water-soluble extractives were removed prior to steam pretreatment. This can be explained by a decreased formation of water-insoluble “pseudo-lignin” from water-soluble bark phenolics during the acid-catalyzed pretreatment, which otherwise results in distorted lignin analysis and may also contribute to the impaired enzymatic digestibility of the barks. Thus, this study advocates the removal of extractives as the first step in the processing of bark or bark-rich materials in a sugar platform biorefinery. 相似文献
105.
B. Ch. Kholkhoev A. S. Buinov S. A. Bal’zhinov V. G. Makotchenko V. E. Fedorov N. A. Aksenova M. N. Kozlova A. B. Solov’eva P. S. Timashev V. F. Burdukovskii 《Polymer Science Series A》2018,60(5):678-682
Highly concentrated dispersions of few-layer graphene stabilized by amphiphilic block copolymer Pluronic F-108 are obtained. According to transmission electron and atomic force microscopy, the thickness of the graphene particles is on average from one to ten layers and their lateral sizes vary from 150 nm to 1 μm. Using these dispersions, new chitosan-based film composites with the filler content up to 5 wt % are obtained; the electrical conductivity of these composites reaches 4.3 × 10–1 S/cm. 相似文献
106.
107.
J. Balázs 《Acta Mathematica Hungarica》1998,80(3):237-248
In this paper we use (0, 2) interpolational polynomials to give an approximate solution of the differential equation y(x) + A(x)y(x) = F(x), x I := [-1, 1] j in case when the boundary values are y(-1) = and y(1) = , , R. 相似文献
108.
Jójárt B Kiss R Viskolcz B Keseru GM 《Journal of chemical information and modeling》2008,48(6):1199-1210
Molecular dynamics (MD) simulations in a membrane-embedded environment were carried out on the homology model of the human histamine H4 receptor (hH4R) alone and in complex with its endogenous activator histamine and with the first reported selective hH4R antagonist JNJ7777120. During the simulation of the histamine-hH4R complex, considerable changes occurred in the hH4R structure as well as in the interaction pattern of histamine at the binding site. These changes are in agreement with experimental data published on GPCR activation. In particular, the intracellular side of TM helix VI moved significantly away from TM helices III and VII. Moreover, histamine formed an interaction with Asn147 (4.57) that was previously proved to be important in hH4R activation. Results of the MD simulations of the native hH4R and the JNJ7777120-hH4R complex suggest that these models represent an inactive conformation of hH4R. MD simulation in the presence of JNJ7777120 resulted in the movement of the intracellular side of TM helix VI in the direction of TM helix III. Snapshots of the simulations may serve as functionally relevant models in the development of novel hH4R ligands in the future. 相似文献
109.
Billes F Várady B 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2008,70(4):729-734
Infrared and Raman spectra of protoporphyrin IX were recorded. DFT quantum chemical calculations were performed. Optimised molecular geometry, electric charge distribution, vibrational force constants were computed. The normal coordinate analysis and the scaling of the force constants yielded all the necessary data for the simulation of the infrared and Raman spectra and the potential energy distribution calculations. The result was the interpretation of all vibrational modes of the molecule. Conclusions were drawn from the difficulties arisen during the assignment of the vibrational spectra of such large molecules. 相似文献
110.
Dr. Christian Marquardt M. Sc. Tobias Kahoun Dr. Andreas Stauber Dr. Gábor Balázs Dr. Michael Bodensteiner Prof. Dr. Alexey Y. Timoshkin Prof. Dr. Manfred Scheer 《Angewandte Chemie (International ed. in English)》2016,55(47):14828-14832
We report on the synthesis and structural characterization of unprecedented anionic parent compounds of mixed Group 13/15 elements. The reactions of the pnictogenylboranes H2E‐BH2?NMe3 ( 1 a =P, 1 b =As) with phosphorus and arsenic centered nucleophiles of the type [EH2]? (E=P, As) lead to the formation of compounds of the type [H2E‐BH2‐E′H2]? ( 2 : E=E′=P; 3 : E=E′=As; 4 : E=P, E′=As) containing anionic pnictogen–boron chain‐like units. Furthermore, a longer 5‐membered chain species [H2As‐BH2‐PH2‐BH2‐AsH2]? ( 5 ) and a cyclic compound [NHCdipp‐H2B‐PH2‐BH2‐NHCdipp]+[P5B5H19]? ( 6 ) containing a n‐butylcyclohexane‐like anion were obtained. All the compounds have been characterized by X‐ray structure analysis, multinuclear NMR spectroscopy, IR spectroscopy, and mass spectrometry. DFT calculations elucidate their high thermodynamic stability, the charge distribution, and give insight into the reaction pathway. 相似文献