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171.
Moon Hwan Cho Seung Chang Yang Nam Keun Yang Yongjin Kang Jaejung Ko 《Journal of inclusion phenomena and macrocyclic chemistry》1998,30(4):279-287
The thermodynamic parameters for the interaction of Cu2+, Ni2+, Co2+, Cd2+, andAg+ with the new title ligand have been determined by titration calorimetry in 50% THF–methanol (V/V) at 25 °C.Ag+ exhibited remarkably higher complexation selectivity.Ag+ and several transition metal ions have been transportedusing this ligand as carrier in a bulk liquid membrane. CompetitiveAg+–M2+ transport studies have also beencarried out for the same system. In this membrane transport study, high transport of Ag+ was observed in both single and competitiveAg+–M2+ transport studies. The complexformation of N,N-bis[o-(diphenylphosphino)benzylidene]ethylenediamine (P2N2) with silver,[Ag(P2N2)] (NO3), (1) is reported. Complex 1 has been characterized by X-ray crystallography. 1 ismonoclinic, space group P21/n (No. 14), with cell dimensionsa = 13.398(4) , b=12.577(5) , c = 21.521(4) , =100.14(2) , V = 3570(2) 3 and Z = 4. 相似文献
172.
The large number of possible chemical reactions represents a severe burdenfor modeling of even relatively simple plasma systems. Reduced sets ofchemical reactions have been obtained for numerical simulations of nitrogenand nitrogen-hydrogen plasma jets flowing into an atmospheric airenvironment. The important or active reactions are determined based on asimplified reduction method. A reaction is considered active if it leadsto higher sensitivities than a specified cutoff sensitivity of 1%. Theactive reactions exert a significant influence on main plasma parameters,such as velocity, temperature, and species concentrations. The sensitivityanalysis for the specified systems shows that two NO reactions, known asZel'dovich reactions (N2+ONO+N andNO+OO2+N),(1) are both active in a nitrogenplasma jet. On the other hand, the latter is not active and may be omittedin a nitrogen–hydrogen plasma jet. A nitrogen–hydrogen plasmajet requires contribution of two active charge exchange reactions:N2+N+N+
2+N andN+H+N+ +H, while only the former is needed in a nitrogen plasmajet. The dissociation reactions are all active in both plasma jets, exceptthe dissociation of OH. 相似文献
173.
The mixture of silver iodide and ferrocene is used to prepare the membrane of iodide ion-selective electrode. The interference of sulfide can be reduced by the addition of cupric ion in the test solution. Ethylene glycol is determined by potentiometric titration using iodine ion-selective electrode as an indicator electrode. 相似文献
174.
A new catalytic kinetic spectrophotometric method has been developed for the determination of trace amount of manganese (II) in nonionic microemulsion medium. The method is based on the catalytic effect of manganese (II) on the oxidation of dahlia violet by potassium periodate with nitrilotriacetic acid as an activitor in the presence of nonionic microemulsion. Under the optimum conditions, the calibration graph is linear in the range of 0.0004-0.0056 μg ml−1 of manganese (II) at 580 nm. The detection limit achieved is 3.75×10−5 μg ml−1. Manganese (II) in foodstuff samples was determined with satisfactory results. 相似文献
175.
Silica nanoparticles for separation of biologically active amines by capillary electrophoresis with laser-induced native fluorescence detection 总被引:1,自引:0,他引:1
This paper describes the analysis of biologically active amines by capillary electrophoresis (CE) in conjunction with laser-induced native fluorescence detection. In order to simultaneously analyze amines and acids as well as to achieve high sensitivity, 10 mM formic acid solutions (pH < 4.0) containing silica nanoparticles (SiNPs) were chosen as the background electrolytes. With increasing SiNP concentration, the migration times for seven analytes decrease as a result of increase in electroosmotic flow (EOF) and decrease in their electrophoretic mobilities against EOF. A small EOF generated at pH 3.0 reveals adsorption of SiNPs on the deactivated capillary wall. The decreases in electrophoretic mobilities with increasing SiNP concentration up to 0.3x indicate the interactions between the analytes and the SiNPs. Having a great sensitivity (the limits of detection at a signal-to-noise ratio (S/N) = 3 of 0.09 nM for tryptamine (TA)), high efficiency, and excellent reproducibility (less than 2.4% of the migration times), this developed method has been applied to the analysis of urinal samples with the concentrations of 0.50 +/- 0.02 microM, 0.49 +/- 0.04 microM, and 74 +/- 2 microM for TA, 5-hydroxytryptamine, and tryptophan, respectively. The successful examples demonstrated in this study open up a possibility of using functional nanoparticles for the separation of different analytes by CE. 相似文献
176.
Key aspects of the microenvironment surrounding the Fe center in the nitrosyl adduct of iron phthalocyanine, [Fe(Pc)(NO)], have been elucidated from the analysis of the Fe K-edge extended X-ray absorption fine structure (EXAFS) of the material adsorbed on the surface of a high area carbon electrode recorded in situ, in 0.5 M H(2)SO(4). Statistical best fits to the EXAFS data place the Fe center in a five-coordinated square pyramidal configuration shifted away from the Pc plane toward the axially bound NO bent at an angle of ca. 40 degrees with respect to the normal to the Pc plane. This environment is analogous to that of Fe in the nitrosyl adduct of crystalline [Fe(TPP)], where TPP = meso-tetraphenylporphyrinato(2-), determined from X-ray diffraction. 相似文献
177.
The influence of floc structure and floc concentration on the drag acting on a floc is investigated theoretically. A two-layer model is adopted to describe floc structure, and a cell model is used to simulate a floc dispersion. The influences of the key parameters of the problem under consideration, including floc concentration, Reynolds number, the ratio (permeability of outer layer/permeability of inner layer), and the ratio (thickness of outer layer/thickness of inner layer), on the drag coefficient are discussed. We show that the more heterogeneous the floc structure is, the greater the drag and the more significant the deviation of curve of variation of drag coefficient against Reynolds number from a Stokes-law-like relation. The drag on a floc declines with the decrease in floc concentration, and, due to the convective flow of the fluid, the distortion of streamlines surrounding a floc becomes more serious and the deviation of the variation of the curve of drag against Reynolds number from a Stokes-law-like relation is more significant. 相似文献
178.
[reaction: see text] Continuing from the syntheses and the antibacterial studies of a library of pyranmycins, we further probed the proximity around ring III of pyranmycin by introducing an "extended arm" that has hydroxyethyl or aminoethyl groups at the O-2' ', O-3' ', or O-4' ' positions. The results from the antibacterial studies reveal the optimal structural motif is the attachment of an extended arm with a terminal hydroxyl group at the O-3' ' position. 相似文献
179.
Sung Woo Moon Gun-Dae Lee Seong Soo Park Seong-Soo Hong 《Reaction Kinetics and Catalysis Letters》2004,82(2):303-310
Catalytic combustion of chlorobenzene over supported vanadium oxides has been investigated. TiO2 was prepared by the sol-gel method from titanium isopropoxide. The supported vanadium oxide catalysts have been prepared
by precipitation-deposition and impregnation method and characterized by XRD, FT-Raman and TPR. In the VOx/TiO2catalysts prepared using the impregnation method, when vanadium loading reaches 3 wt.%, the activity shows a maximum. However,
in the VOx/TiO2catalysts prepared by precipitation-deposition, when vanadium loading reaches 7 wt.%, the activity shows a maximum. This result
suggests that the precipitation-deposition can yield a higher metal loading on the support and a high dispersion compared
to the impregnation method.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
180.