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981.
Prof. Dr. Stephan Schulz Sarah Schmidt Dieter Bläser Christoph Wölper 《无机化学与普通化学杂志》2012,638(11):1705-1710
Zincocene Cp*2Zn reacts with carbodiimides C(NR)2 with insertion into the Zn–Cp* bond and formation of [(Cp*C(NR)2]2Zn [R = Et ( 1 ), iPr ( 2 ), Cy ( 3 )]. In addition, the reaction of Cp*2Zn with CS2 under dry conditions gives (Cp*CS2)2Zn ( 4 ), whereas in the presence of a small amount of water [Zn4(μ4‐O)(S2CCp*)6] ( 5 ) is obtained. Compounds 1 – 4 were characterized by NMR (1H, 13C) and IR spectroscopy as well as elemental analysis and single‐crystal X‐ray diffraction ( 2 – 4 , 5 of poor quality). The solid‐state structure of 5 is comparable to the carboxylate complex previously obtained from the reaction of Cp*2Zn with CO2. 相似文献
982.
Based on the new binuclear gold(I) complex [(AuCl)2(L1)] (1) (L1?=?2,3-bis(diphenylphosphino)maleic anhydride) four new polynuclear compounds were synthesized by reactions of 1 with E(SiMe3)2 (E?=?S, Se). During the formation of these new compounds the initial ligand L1 undergoes various transformations (e.g. substitution, hydration or hydrogenation) leading to the new ligands: trans-2,3-bis(diphenylphosphino)succinic anhydride (L2), 2-diphenylphosphino-3-mercapto-maleic anhydride anion (L3), 2-diphenylphosphino-3-selenolato-maleic anhydride anion (L4) and 2,3-bis(diphenylphosphino)succinic acid (L5). In case of using the sulfur species S(SiMe3)2 a pentanuclear cluster, [Au5(PPh2)3(L3)2] (2), and a 24-nuclear cluster, [Au24S6(PPh2)4(L3)8] (3), could be obtained. With Se(SiMe3)2 the binuclear complex, [(AuCl)2(L2)] (4), and the dodecanuclear cluster, [Au12Se4(L4)4(L5)2] (5), were yielded. 相似文献
983.
Weiss VU Subirats X Pickl-Herk A Bilek G Winkler W Kumar M Allmaier G Blaas D Kenndler E 《Electrophoresis》2012,33(12):1833-1841
During infection, enteroviruses, such as human rhinoviruses (HRVs), convert from the native, infective form with a sedimentation coefficient of 150S to empty subviral particles sedimenting at 80S (B particles). B particles lack viral capsid protein 4 (VP4) and the single-stranded RNA genome. On the way to this end stage, a metastable intermediate particle is observed in the cell early after infection. This subviral A particle still contains the RNA but lacks VP4 and sediments at 135S. Native (150S) HRV serotype 2 (HRV2) as well as its empty (80S) capsid have been well characterized by capillary electrophoresis. In the present paper, we demonstrate separation of at least two forms of subviral A particles on the midway between native virions and empty 80S capsids by CE. For one of these intermediates, we established a reproducible way for its preparation and characterized this particle in terms of its electrophoretic mobility and its appearance in transmission electron microscopy (TEM). Furthermore, the conversion of this intermediate to 80S particles was investigated. Gas-phase electrophoretic mobility molecular analysis (GEMMA) yielded additional insights into sample composition. More data on particle characterization including its protein composition and RNA content (for unambiguous identification of the detected intermediate as subviral A particle) will be presented in the second part of the publication. 相似文献
984.
Based on the normalized elimination of the small component relativistic formalism, a new approach to the calculation of hyperfine structure parameters of paramagnetic molecules is developed and implemented. The new method is tested in the calculation of the isotropic hyperfine structure constant for a series of open-shell molecules containing mercury. The results of calculations carried out in connection with ab initio methods of increasing complexity demonstrate the high accuracy of the formalism developed. In view of its computational simplicity, the new approach provides the basis for an efficient and accurate calculation of the HFS parameters of large molecules. 相似文献
985.
The existing combinatorial methods for iso-surface computation are efficient for pure visualization purposes, but it is known that the resulting iso-surfaces can have holes, and topological problems like missing or wrong connectivity can appear. To avoid such problems, we introduce a graph-theoretical method for the computation of iso-surfaces on cuboid meshes in ℝ3. (© 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
986.
The reactions of CuCl and tBuTeSiMe3 in the presence of phosphine ligands result in the formation of four new Cu/Te cluster complexes, [Cu18Te6(TetBu)6(PPh2Et)7], [Cu19Te6(TetBu)7(PEt3)8], [Cu27Te15(PiPr2Me)12] and [Cu58Te32(PtBu2
nBu)14], which have been structurally characterized by single crystal structural analysis. The former two clusters show a layer-type tellurium frameworks in which the copper atoms are asymmetrically spread. The latter two clusters possess a tellurium framework in a body-centered Te14-Frank-Kasper polyhedron or a Te28 polyhedron with four interstitial tellurium atoms and belong to mixed-valence Cu/Te compounds. 相似文献
987.
Alexander V. Virovets Irina V. Kalinina Vladimir P. Fedin Dieter Fenske 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(12):e589-e590
During an investigation of the W/Te/Br2 system, we prepared crystals of the title compound, C20H40N4S8Te, from acetonitrile solution by slow addition of diethyl ether. It appeared to be a new tetragonal modification. The calculated density of the tetragonal modification (1.513 Mg m?3) is slightly greater than found for the known orthorhombic modification (1.46 Mg m?3). The bond distances and angles are practically the same. 相似文献
988.
Mirjam Witthaut Rainer Cremer Klaus Reichert Dieter Neuschütz 《Mikrochimica acta》2000,133(1-4):191-196
(Al,Cr)2O3 layers were deposited on cemented carbide insert tips at a substrate temperature of 500 °C by means of reactive magnetron
sputtering. An Al target was sputtered in RF mode and a Cr target in DC mode simultaneously in an oxygen/argon plasma. The
influence of the Al and Cr sputter power and of the oxygen partial pressure on composition and structure of the (Al,Cr)2O3 layers as well as on the binding states of their components were investigated.
Special attention was paid to the interpretation of the O ls and O-KLL fine structure and peak shifts. For the binary phases
γ-Al2O3 and Cr2O3, a good agreement with literature values was observed in each case. In case of the ternary phases a continuous shift of the
energetic position of the O1s peak, the O-KL23L23 transition and the modified Auger parameter α ′ of oxygen between the two binary phases γ-Al2O3 and Cr2O3 could be detected, indicating a wide range of solid solubility between Al2O3 and Cr2O3. As revealed by grazing incidence X-ray diffraction, the crystallinity of the ternary phases is less pronounced as compared
to the binaries and increases with increasing oxygen flow rate. 相似文献
989.
Friederike Kramer Dieter Klemm Dieter Schumann Nadine Heßler Falko Wesarg Wolfgang Fried Dietmar Stadermann 《Macromolecular Symposia》2006,244(1):136-148
Summary: Using a “never-dried” procedure (according to Figure 4) shaped bacterial nanocellulose (BC, 1% cellulose, 99% water) has been modified by the formation of BC-polymer composites. For this purpose, acrylate and methacrylate monomers and methacrylate crosslinkers were photopolymerized inside an ethanol-swollen nanofiber network. Using the ethanol as solvent and as confirmed by model reactions the synthetic polymer (SP) part of the composites is constructed of crosslinked polymers (number of repeating units in the range of 500). As part of ongoing work on the development of (bio)materials from the innovative pool of BC composites these investigations are recently directed towards the creation of collagen-like materials. Thus, for these purposes, mainly water absorption capacity, strength, and elasticity have to be controlled, whilst still retaining essential features of BC like shape, nanofiber network, pore system, and proved biocompatibility. Using acrylic acid, 2-ethylhexyl acrylate, 2-hydroxyethyl methacrylate, N-vinyl pyrrolidone as acrylate monomers and triethylene glycol dimethacrylate and 1,4-butandiol dimethacrylate as crosslinkers of different concentrations either a filling of the pores or a coating of the fibers in the BC nanocomposites could be achieved. The small cellulose content of the composites significantly increases the water absorption value and the strength of the material as well as the ability of re-swelling in the case of fiber coated composites. Sample 12 is an optimized BC-SP composite regarding important properties of hyaline cartilage like Young's modulus in the range of 5–20 MPa using the well-known Simplex-method. 相似文献
990.
Dimitar I. Dimitrov Andrey Milchev Kurt Binder Dieter W. Heermann 《Macromolecular theory and simulations》2006,15(7):573-583
Summary: Molecular dynamics simulations of a coarse‐grained bead‐spring model of flexible macromolecules tethered with one end to the surface of a cylindrical pore are presented. Chain length N and grafting density σ are varied over a wide range and the crossover from “mushroom” to “brush” behavior is studied for three pore diameters. The monomer density profile and the distribution of the free chain ends are computed and compared to the corresponding model of polymer brushes at flat substrates. It is found that there exists a regime of N and σ for large enough pore diameter where the brush height in the pore exceeds the brush height on the flat substrate, while for large enough N and σ (and small enough pore diameters) the opposite behavior occurs, i.e. the brush is compressed by confinement. These findings are used to discuss the corresponding theories on polymer brushes at concave substrates.