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101.
The course of the non-isothermal decomposition of CrO3 in air was explored kinetically, by using a number of widely accepted methods. The credibility of the values obtained from a given kinetic parameter (the reaction order, the activation energy and the frequency factor) was justified on the grounds of (i) a multiple correlation coefficient, and (ii) the merits and demerits of the method adopted. The results obtained may help towards a characterization of the non-isothermal conditions under which the encountered decomposition events and products could be resolved. The study was motivated by the results of previous physicochemical characterization studies [1, 2], in which catalytically important intermediates CrOx(3<x<6) were structurally identified.  相似文献   
102.
We describe a new method that allows photopolymerization of hydrogels to occur on surfaces functionalized with eosin. In this work, glass and silicon surfaces were derivatized with eosin and photopolymerization was carried out using visible light (514 nm). This mild condition may have advantages over methods that use ultraviolet (UV) light (e.g., for encapsulation of cells and proteins, in drug screening, or in biosensing applications). The hydrogel formed on the modified surface is remarkably stable for an extended period of time. The resultant hydrogel was hydrated for more than 18 months without suffering delamination from the substrate surface. This strongly suggests covalent attachment of the hydrogel to the surface. Contact angle titration measurements and X-ray photoelectron spectroscopy analysis of eosin surfaces before and after irradiation in the presence of triethanolamine suggest that the eosin radical is responsible for the covalent attachment of the gel onto the substrate surface. This method allows for 2-D patterning of hydrogels, which is demonstrated here using the microcontact printing technique. However, noncontact photolithography could be used to form similar patterns by directing light through a mask. This method can be easily implemented to form arrays of fluorophores and proteins in situ.  相似文献   
103.
Mu-chloro-mu-[2,5-bis(2-pyridyl)-1,3,4-thiadiazole] aqua chlorocopper(II) dichlorocopper(II) is the first characterized dimeric complex of a transition metal and this hetero ligand [C(12)H(10)Cl(4)Cu(2)N(4)OS; triclinic; space group P; a = 9.296(3) A, b = 9.933(3) A, c = 10.412(3) A; alpha = 79.054(5) degrees, beta = 82.478(6) degrees, gamma = 67.099(5) degrees; Z = 2 at room temperature]. The Cu(II) ions are bridged by the N-N thiadiazole bond and a chloride ion [Cu1-Cu2 = 3.7800(8) A]. Thermogravimetric analysis shows this structure to be stable at temperatures up to 348 K. At higher temperatures, the successive loss of a water molecule and one chloride of the dimeric unit is identified. From room temperature to 125 K, half of the Cu(2+) ions are progressively engaged in intermolecular dinuclear antiferromagnetic exchanges, while the other half remain paramagnetic. At lower temperatures, both susceptibility and electron paramagnetic resonance measurements show the paramagnetic-only couplings of this half of the Cu(2+) ions, involving a singlet ground state for interacting Cu(2+). This unusual behavior has been satisfactorily explained on the basis of intermolecular Cu-Cu interactions (J = -180 cm(-1)), involving the magnetic d(z)2 orbital perpendicular to the molecular plane, on which are seen the conjugate effects of the bridging chloride and the planar thiadiazole. It is noteworthy that the behavior of the title compound is original, compared to the systematic in-plane intramolecular antiferromagnetic coupling of other thiadiazole-containing binuclear complexes.  相似文献   
104.
A 5 wt% Pd/SiO2 catalyst was synthesized by heating PdCl2-impregnated SiO2 in H2 at 300°C for 2 h. It was found that the metal particle dispersion is improved when the reduction step is preceded by calcination at 300°C for 2h. Thermogravimetry of the impregnated support in air, N2 and H2 atmospheres was used to monitor the interactions occurring during the various preparative steps (i.e. drying, calcination and reduction) of the catalyst. The solid prduct of each preparative step was characterized by X-ray diffractometry and UV/Vis diffuse reflectance spectroscopy. The results indicate that following the drying step (at 110°C in air) the palladium occurs in two detectable forms: PdCl2 particles and Si?O?Pdn+ surface species. The calcination appears to transform the PdCl2 particles into the latter surface species. The H2-reduction eventually converts the surface species into finely-dispersed Pd° metal particles (average size=8–14 nm). No other reduction products, such as PdySix, were detected.  相似文献   
105.
Summary Several penta-and tetracyanooxomolybdenum(IV) anions have been synthesized containing different numbers of H2O molecules, either coordinated or present as crystallisation molecules. The influence of these molecules on the reactivity of the complex, especially towards O2, is discussed. Three compounds were characterized by x-ray structure determination. [Mo(O)(CN)5(H2O)2(MeCN)2][PPh4]4Cl belongs to triclinic space group P-1 witha=13.146(3) Å,b=16.944(5) Å,c=21.761(6) Å, =84.72(2)°, =87.15(2)° and =85.25(2)°. The volume of the unit cell is 4678(6)Å3 withz=2. The structure was refined to R=6.5%. [Mo(O)(CN)4(H2O)·6H2O][PPh4]2 belongs to monoclinic space group P21/n witha=15.313(2)Å,b=19.983(3)Å,c=17.006(2)Å, =100.51(2)°. The volume of the unit cell is 5117(3)Å3 withz=4. The structure was refined to R=8.7%. [Mo(O)(CN)4(MeCN)](PH3)2N]2 belongs to triclinic space group P-1 witha=13.770(4)Å,b=16.292(5)Å,c=16.889(5)Å, =73.23(2)°, =72.02(2)° and =71.57(2)°. The volume of the unit cell is 3342(3)Å3 withz=2. The structure was refined to R=7.2%.  相似文献   
106.
3‐Diethylaminoacrylonitrile ( 1 ) reacts with hydrazonyl halides ( 2a‐d ) to yield 1,3‐disubstituted pyrazole‐4‐carbonitriles 5a‐d. The acetyl 1‐p‐chlorophenylpyrazole‐4‐carbonitrile ( 5a ) condensed with hydrazine hydrate to yield the bishydrazone 10 and with dimethylformamide dimethylacetal to yield 1‐aryl‐3‐(3‐dimethylamino)acryloyl pyrazole‐4‐carbonitrile ( 11 ). This enamine reacts with hydrazine hydrate to yield the pyrazolylpyrazole ( 12 ) and with naphthoquinone to yield the 3‐naphthofuranoyl pyrazole 13. The pyra‐zolyl pyridine derivative 14 was obtained upon treatment of 11 with acetylacetone in the presence of ammonium acetate. Compound 11 was coupled with p‐chlorobenzene diazonium chloride to yield the hydrazone 16 that was coupled further with p‐chlorobenzenediazonium chloride to yield the formazane 18.  相似文献   
107.
Benzocycloheptapyrimidines are an important class of compounds because of their pharmacological properties. We report here two new synthetic procedures for the preparation of 2,4-dialkylamino substituted benzocycloheptapyrimidines. One of these methods is based on the reaction of substituted cyanamides with the vinyl triflate of the 1-benzosuberone while the other preparation relies on the nucleophilic displacement of methylsulfonyl groups by secondary amines at the 2 and 4 positions of benzocycloheptapyrimidine intermediates.  相似文献   
108.
Mechanochemical solvent‐free reactions by milling, grinding or other types of mechanical action have emerged as a viable alternative to solution chemistry. Mechanochemistry offers not only a possibility to eliminate the need for bulk solvent use, and reduce the generation of waste, but it also unlocks the door to a different reaction environment in which synthetic strategies, reactions and molecules previously not accessible in solution, can be achieved. This Minireview examines the potential of mechanochemistry in chemical and materials synthesis, by providing a cross‐section of the recent developments in using ball milling for the formation of molecules and materials based on covalent and coordination bonds.  相似文献   
109.
110.
The development of biocompatible fluorescent materials based on CdII (d10) systems for cytotoxic application and latent fingerprint detection under UV illumination has not yet been studied that thoroughly. In this sense, this work presents production of novel and dual nature pure Cd (II) phosphor complex based on ρ-dimethylaminobenzaldehyde thiosemicarbazone ligand (H-DMABTS). The structural characterization confirms that the ligand which acts as monoanionic bidentate through NS donor sites, forming mononuclear complex formulates as: [Cd (DMABTS)2(C2H5OH)2] where, DMABTS = anionic form of ρ-dimethylaminobenzaldehyde thiosemicarbazone. TEM analysis shows that Cd (II) complex has sheet like shape in micro scale. Moreover, the Cd (II) complex was dispersed into silica host. Photoluminescence emission and lifetime of H-DMABTS ligand, Cd (II) complex and Cd (II) complex dispersied into silica were measured. Cd (II) complex is intensive luminescent with impressive visual emission under UV excitation. All fluorescent materials were tested for their in vitro cytotoxicity against HepG-2 cell line. The Cd (II) phosphor complex shows higher activity (IC50 = 0.005 μM) than other prepared materials and different standard antitumor drugs. Furthermore, the Cd (II) phosphor complex has a lower toxicity value (LD50 = 130 mg/Kg) relative to the standard cis-platin (LD50 = 13.5 mg/Kg). Moreover, latent prints details, including their characteristic three levels, have been clearly identified from various forensic substrates (non-porous, semi-porous, porous) using Cd (II) phosphor complex.  相似文献   
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