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861.
Jií Kvapil Bohumil Perner Josef Kvapil Karel Blaek 《Crystal Research and Technology》1980,15(10):1163-1166
Doping possibilities of Al2O3 and YAG crystals grown from the melt alternatively doped with alkali earth, silicon, iron group or molybdenum ions under 98% Ar – 2% H2 or 98% He – 2% H2 protective atmosphere are described. Alkali earth and particularly Si ions evaporate slowly from the melt. Reduction of iron group ions was observed. Mo may enter YAG phase using a wet protective atmosphere. Al2O3 phase contains Mo ions if grown from the electrolyzed melt. 相似文献
862.
Cell quantification is widely used both in basic and applied research. A typical example of its use is drug discovery research. Presently, plenty of methods for cell quantification are available. In this review, the basic techniques used for cell quantification, with a special emphasis on techniques based on fluorescent DNA dyes, are described. The main aim of this review is to guide readers through the possibilities of cell quantification with various methods and to show the strengths and weaknesses of these methods, especially with respect to their sensitivity, accuracy, and length. As these methods are frequently accompanied by an analysis of cell proliferation and cell viability, some of these approaches are also described. 相似文献
863.
Jitka Havrnkov Zuzana Limpouchov Karel Prochzka 《Macromolecular theory and simulations》2003,12(7):512-523
Lattice Monte Carlo simulations of conformations of hereroarm star copolymers AnBn in selective solvents were performed using a special variant of the Siepman and Frenkel algorithm. The effects of solvent quality, the number and lengths of blocks on the collapse of the insoluble block A, segregation of the two types of blocks and the behavior of the soluble blocks B were studied mainly for “hairy” stars containing high numbers of long arms. The simulation shows that insoluble blocks collapse in strongly selective solvents and the gravity centers of soluble and insoluble blocks separate which suggests the possibility of the formation of non‐spherical structures.
864.
The work presents two numerical solutions of compressible flows problems with high and very low Mach numbers. Both problems are numerically solved by finite volume method and the explicit MacCormack scheme using a grid of quadrilateral cells. Moved grid of quadrilateral cells is considered in the form of conservation laws using Arbitrary Lagrangian–Eulerian method. In the first case, inviscid transonic flow through cascade DCA 8% is presented and the numerical results are compared to experimental data. The second case, numerical solution of unsteady viscous flow in the channel for upstream Mach number M∞=0.012 and frequency of the wall motions 100 Hz is presented. The unsteady case can represent a simplified model of airflow coming from the trachea, through the glottal region with periodically vibrating vocal folds to the human vocal tract. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
865.
Jana Krenkova Karel Kleparnik Jaroslav Luksch Frantisek Foret 《Electrophoresis》2019,40(18-19):2263-2270
One of the challenging instrumental aspects in coupling an automated CE instrument with ESI mass spectrometry (CE‐MS) is finding the balance between the stability, reproducibility and sensitivity of the analysis and compatibility with the standard CE instrumentation. Here, we present a development of a new liquid junction based electrospray interface for automated CE‐MS, with a focus on the technical design followed by computer modeling of transport conditions as well as characterization of basic performance of the interface. This hybrid arrangement designed as a microfabricated unit attachable to the automated CE instrument allows using of a wide range of separation capillaries with respect to their diameter, length or internal coating (e.g., for suppressed electroosmotic flow). Different compositions of the ESI liquid and background electrolyte solutions can be used if needed. The microfabricated part, prepared by laser machining from polyimide, includes a self‐aligning liquid junction, a short transport channel, and a pointed sprayer for the electrospray ionization. This microfabricated part is positioned in a plastic connection block securing the separation capillary and flushing ports. Transport conditions were modelled using computer simulation and the real life performance of the interface was compared to that of a commercial sheath liquid interface. The basic performance of the interface was demonstrated by separations of peptides, proteins, and oligosaccharides. 相似文献
866.
Humpolícková J Stepánek M Kral T Benda A Procházka K Hof M 《Journal of fluorescence》2008,18(3-4):679-684
The compaction of DNA plays a role in the nuclei of several types of cells and becomes important in the non-viral gene therapy. Thus, it is in the scope of research interest. It was shown, that spermine-induced compaction of large DNA molecules occurs in a discrete "all-or-non" regime, where the coexistence of free and folded DNA molecules was observed. In the case of intermediate-sized DNA molecules (approximately 10 kbp), so far, it was stated that the mechanism of folding is continuous. Here, we show, that neither a standard benchmark technique-dynamic light scattering, nor a single molecule technique such as fluorescence correlation spectroscopy, can decide what kind of mechanism is undertaken in the compaction process. Besides, we introduce an application of a new approach-fluorescence lifetime correlation spectroscopy. The method takes an advantage of a subtle lifetime change of an intercalating dye PicoGreen during the titration with spermine and based on that, it reveals the discrete mechanism of the process. Furthermore, we show that it allows for observation of the equilibrium state transition dynamics. 相似文献
867.
Treatment of 1-arylmethyl-2-(2-cyanoethyl)aziridines with a nitrile hydratase afforded the corresponding 2-(2-carbamoylethyl)aziridines, which underwent rearrangement into 5-hydroxypiperidin-2-ones upon heating under microwave irradiation. In addition, treatment of 2-(2-cyanoethyl)aziridines with a nitrilase selectively afforded 5-hydroxypiperidin-2-ones in good yields. On the other hand, chemical hydrolysis of 2-(2-cyanoethyl)aziridines using KOH in EtOH/H(2)O furnished the corresponding potassium 3-(aziridin-2-yl)propanoates, which, upon acidification with acetic acid, smoothly rearranged into 4-(aminomethyl)butyrolactones. 相似文献
868.
Karel Mach Jií Kubita Ivana Císaov Petr tpni
ka 《Acta Crystallographica. Section C, Structural Chemistry》2002,58(2):m116-m118
Reacting stoichiometric amounts of 1‐(diphenylphosphino)ferrocenecarboxylic acid and [Ti(η5‐C5HMe4)2(η2‐Me3SiC[triple‐bond]CSiMe3)] produced the title carboxylatotitanocene complex, [{μ‐1κ2O,O′:2(η5)‐C5H4CO2}{2(η5)‐C5H4P(C6H5)2}{1(η5)‐C5H(CH3)4}2FeIITiIII] or [FeTi(C9H13)2(C6H4O2)(C17H14P)]. The angle subtended by the Ti/O/O′ plane, where O and O′ are the donor atoms of the κ2‐carboxylate group, and the plane of the carboxyl‐substituted ferrocene cyclopentadienyl is 24.93 (6)°. 相似文献
869.
Trávníček Zdeněk Maloň Michal Popa Igor Doležal Karel Strnad Miroslav 《Transition Metal Chemistry》2002,27(8):918-923
Nickel(II) complexes with 6-benzylaminopurine (BAP) derivatives, namely 6-(3-chlorobenzylamino)purine (HL1), 6-(4-chlorobenzylamino)purine (HL2) and 6-(4-fluorobenzylamino)purine (HL3), have been prepared and characterized by elemental analyses, i.r., u.v.–v.i.s., ES+ and FAB+ mass spectroscopy, magnetic susceptibility and conductivity measurements, and by thermal analysis. The complexes are: [Ni(L1(H2O)2Cl] · H2O, [Ni(L1)(H2O)-(NO3)] · H2O, [Ni(L2)(H2O)2Cl], [Ni(L2)(H2O)2(NO3)] · H2O, [Ni(HL2)(H2O)Cl2] · EtOH and [Ni(L3)(H2O)2Cl]. They have been tested in vitro for their possible cytotoxic activity against G-361 (human malignant melanoma), HOS (human osteogenic sarcoma), K-562 (human chronic myelogenous leukemia) and MCF-7 (human breast adenocarcinoma) cell lines. 相似文献
870.
We prepared a series of low-molecular-mass fluorescent ampholytes with narrow pI range. These fluorescein-based ampholytes are detection compatible with argon laser-induced fluorescence (LIF) detection. The selected properties, important for their routine use as fluorescent pI markers, were examined. The pI values of new fluorescein-based pI markers were determined by capillary isoelectric focusing (CIEF) using currently available low-molecular-mass pI markers for CIEF with photometric detection. The examples of CIEF with fluorometric detection of new compounds together with fluorescein isothiocyanate (FITC) derivatized proteins are presented. 相似文献