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A mild one-pot method for the synthesis of acyclic N-(1-methoxyalkyl)amides starting from carboxylic acids and methyl imidates had been developed and applied to the total synthesis of the insect poison pederine . 相似文献
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25.
Takehiko Yamato Masashi Yasumatsu Yoshiyuki Saruwatari Louis Korbla Doamekpor 《Journal of inclusion phenomena and macrocyclic chemistry》1994,19(1-4):315-331
Novel macrocyclic compounds, hexahydroxy[1.0.1.0.1.0]- (2b) and octahydroxy[1.0.1.0.1.0.1.0]metacyclophane (2c) have been prepared in 50–70% yield by base-catalyzed condensation of 5,5-di-tert-butyl-2,2-dihydroxybiphenyl (1) with formaldehyde in refluxing xylene. An attempted alkylation of the flexible macrocycles2b and2c with ethyl bromoacetate in the presence of Cs2CO3 under acetonitrile reflux gave only one pure stereoisomer3 and4, respectively, while other possible isomers were not observed. The structural characterization of these products is also discussed. The two-phase solvent extraction data indicated that hexaethyl ester3 and octaethyl ester4 show strong metal affinity, comparable with that of the corresponding calix[n]arenes, and a high K+ selectivity was observed for octaethyl ester4.1H-NMR titration of hexaethyl ester3 and octaethyl ester4 with KSCN clearly demonstrate that a 11 complex is formed which is stable on the NMR time scale.This paper is dedicated to the commemorative issue on the 50th anniversary of calixarenes. 相似文献
26.
The equilibrium constants, K
2, have been determined for the proton-transfer reactions of 1-phenacylquinolinium ion, PHQ+, with several amines {triethylamine (TEA), N,N,N′,N′-tetramethylethylenediamine (ED), N,N,N′, N′-tetramethylpropanediamine (PD), N,N,N′,N′-tetramethylbutanediamine (BD), and 1,8-bis(dimethylamino-naphthalene (DMAN)} in acetonitrile (AN), AN-tetrahydrofuran (THF)
and AN-ethanol (EtOH) mixtures. The reaction was followed spectrophotometrically using a stopped-flow technique. The K
2 value decreased for DMAN and increased for TEA with increasing vol-% of THF in AN-THF mixtures. The changes in the K
2 value for ED, PD and BD changed in the order: ED, PD and BD from a pattern similar to TEA to a pattern similar to DMAN. The
change in the K
2 value for DMAN with increasing vol-% of THF in AN-THF mixtures was explained by the effect of polarity on the stability of
P−Q+ (the deprotonated product of PHQ+). The effect of THF on the K
2 value is consistent with that of the peak wavelength of the absorption spectrum of P−Q+. The change in the K
2 value for TEA, ED, PD and BD depended on the structures of the protonated bases, one of the products for this reaction. The
effect of EtOH on the K
2 value for DMAN was examined in ternary EtOH-THF-AN mixtures that contain different amounts of EtOH and whose relative permittivities
were adjusted to that of EtOH. The K
2 value increased with increasing vol-% of EtOH because of the stabilization of P−Q+ upon the formation of the hydrogen-bonded complex with EtOH. The absorption spectrum of P−Q+ demonstrated a blue shift as the vol-% of EtOH increased. 相似文献
27.
Matsumoto T Kamada Y Sugimoto T Tada T Noguchi S Nakazumi H Shiro M Yoshino H Murata K 《Inorganic chemistry》2003,42(17):5192-5201
Two donor molecules newly synthesized, dimethylthio- and ethylenedithio-tetrathiafulvalenothioquinone-1,3-diselenolemethides (1 and 2), were used to prepare their charge-transfer (CT) salts with a magnetic FeBr(4)(-) counteranion. For 1, a low electrical conducting 1:1 salt (1.FeBr(4)) was obtained, in which molecules of 1 are tightly dimerized in a one-dimensional (1D) stacking column. On the other hand, 2 gave a 2:1 salt (2(2).FeBr(4)) as two different kinds of plate crystals (I and II). Both I and II possess similar stacking structures of molecules of 2 in each 1D column with a half-cut pipelike structure along the c axis. However, for I, the stacking columns are aligned in the same direction along the a and b axes, while for II they are in the same direction along the a axis, but in the reverse direction along the b axis, resulting in the difference in the relative arrangement of molecules of 2 and FeBr(4)(-) ions between the two crystals. The room-temperature electrical conductivities of the single crystals of I and II were 13.6 and 12.7 S cm(-)(1), respectively. The electrical conducting behavior in I was metallic above 170 K but changed to be semiconducting with a very small activation energy of 7.0 meV in the temperature range 4-170 K. In contrast, II showed the semiconducting behavior in the whole temperature range 77-285 K. The corresponding nonmagnetic GaBr(4)(-) salts with almost the same crystal structure as I and II showed definitively different electrical conducting properties in the metal to semiconductor transition temperature in I as well as in the magnitude of activation energy in the semiconducting region of I and II. The interaction between the d spins of FeBr(4)(-) ions was weak and antiferromagnetic in both I and II, but the magnitude of the spin interaction was unexpectedly larger compared with that in the FeBr(4)(-) salt of the corresponding sulfur derivative of 2 with closer contact between the neighboring FeBr(4)(-) ions. These electrical conducting and magnetic results suggest a significant interaction between the conducting pi electrons and the d spins of FeBr(4)(-) ions located near the columns or layers. 相似文献
28.
Murakami H Kawabuchi A Matsumoto R Ido T Nakashima N 《Journal of the American Chemical Society》2005,127(45):15891-15899
The shuttling process of alpha-CyD in three rotaxanes (1-3) containing alpha-cyclodextrin (alpha-CyD) as a ring, azobenzene as a photoactive group, viologen as an energy barrier for slipping of the ring, and 2,4-dinitrobenzene as a stopper was investigated. The trans-cis photoisomerization of 1 by UV light irradiation occurred in both DMSO and water due to the movement of alpha-CyD toward the ethylene group, while the photoisomerization of 2 occurred in DMSO, but not in water. No photoisomerization was observed for 3 in both water and DMSO. The activation parameters of 1 and 1-ref in DMSO are subject to a compensation relation between deltaS(double dagger) and deltaH(double dagger); however, in water, the deltaS(double dagger) terms are not compensated by the deltaH(double dagger) terms. Alternating irradiation of the UV and visible lights resulted in a reversible change in the induced circular dichroism (ICD) bands of trans-1 and cis-1. In contrast, after the UV light irradiation, the ICD band of trans-2 decreased without the appearance of any bands of cis-2. The NMR spectra of 2 in DMSO showed coalescence of the split signals for the methylene and for the viologen protons due to the shuttling of alpha-CyD. Both the NOE differential spectra for cis-1 in water after UV light irradiation and 2 in DMSO after heating to 120 degrees C showed the negative NOE peaks assigned to interior protons of alpha-CyD, suggesting that alpha-CyD in cis-1 exists at the one ethylene moiety, and alpha-CyDs in cis-2 and 2 heated in DMSO exist at the propylene moieties. 相似文献
29.
S Yokohama T Miwa S Aibara H Fujiwara H Matsumoto K Nakayama T Iwamoto M Mori R Moroi W Tsukada 《Chemical & pharmaceutical bulletin》1992,40(9):2391-2398
A series of 6-alkyl- or 6-(cycloalkylalkyl)-[1,3,4]thiadiazolo[3,2- a]-1,2,3-triazolo[4,5-d]pyrimidin-9(3H)-ones 1b--o was synthesized from the corresponding 1,3,4-thiadiazol-5-amines 3b--o and the antiallergic activities of the products were evaluated. Among the compounds 6-(2-cyclohexylethyl)- [1,3,4]thiadiazolo[3,2-a]-1,2,3-triazolo[4,5-d]pyrimidin-9(3H)-one 1h, whose X-ray crystallographic stereostructure is shown, was found to be a promising new antiallergic agent, which has low toxicity and dual activity as a leukotriene D4 receptor antagonist and as an orally active mast cell stabilizer. 相似文献
30.
T. Nagaishi S. Ishiyama M. Matsumoto S. Yoshinaga 《Journal of Thermal Analysis and Calorimetry》1984,29(1):121-129
The reactions between ammonium sulphate and three metal oxides (Cr2O3, MnO2 and Fe2O3) were studied. It was confirmed by X-ray diffraction and chemical analysis that stable reaction intermediates were formed consecutively in the course of the reactions.These were (NH4)3M(SO4)3 and NH4M(SO4)2 for Cr2O3 and Fe2O3 and (NH4)2Mn2(SO4)3 for MnO2. The thermal decompositions of these intermediates and of the metal sulphates were carried out. The contracting-volume equation was valid for the decomposition of all the intermediates. The Arrhenius parameters were determined.
Zusammenfassung Es wurden die Reaktionen zwischen Ammoniumsulfat und drei Metalloxiden (Cr2O3, MnO2 und Fe2O3) untersucht. Durch Röntgendiffraktion und chemische Analyse wurde bestätigt, dass im Verlaufe der Reaktion stabile Zwischenprodukte gebildet werden. Es handelt sich dabei um (NH4)3M(SO4)3 und NH4M(SO4)2 im Falle von Cr2O3 und Fe2O3 und um (NH4)2Mn2(SO4)3 im Falle von MnO2. Diese Zwischenprodukte und die Metallsulfate wurden thermisch zersetzt. Die Volumenkontraktionsgleichung war für die Zersetzung all dieser Zwischenprodukte gültig. Die Arrheniusparameter wurden bestimmt.
Cr2O3, MnO2 Fe2O3. , . , (NH4)3M(SO4)3 NH4M(SO4)2, (NH4)2Mn2(SO4)3. . . .相似文献