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291.
3-苯氧甲基-6-(2,4-二氟苯基)-7H-1,2,4-三唑并[3,4-b][1,3,4]噻二嗪的合成与晶体结构研究 总被引:2,自引:0,他引:2
由苯氧乙酸出发,经多步反应,制得3-苯氧甲基-4-氨基-5-巯基-1,2, 4-三唑,它与2-氯-2',4'-二氟苯乙酮进行环化反应,生成3-苯氧甲基-6-( 2,4-二氟苯基)-7H-1,2,4-三唑并[3,4-b][1,3,4]噻二嗪,通过元素分析、红外 光谱、核磁共振氢谱与碳谱、质谱进行表征,并利用单晶X射线衍射法测定其结构 。晶体属单斜晶系、P2_(1/c)空间群,a = 1.339(3) nm, b = 1.4683(4) nm, c = 0.8606(2) nm, β = 108.49(2)°, Z = 4, F(000) = 736, R_1 = 0.0509。还 对均三唑并噻二唑两类稠杂环的晶体结构作了比较。 相似文献
292.
Cis-dioxo-metal complex ( NH3CH2CH2NH2 ) 2.5 [ Mo0.5^(V)W0.5^(VI)O2 ( OC6H4O ) 2] 1 was obtained by the reaction of tetra-butyl ammonium hexamolybdotungstate with 1, 2-dihydroxybenzene in the mixed solvent of CH3OH, CH3CN and ethylenediamine,and characterized by X-ray diffraction, UV-vis and EPR analysis. Compared with its analogous complexes (NH3CH2CH2NH2)3[Mo^(V)O2(OC6H40)2] 2 and (NH3CH2CH2NH2)2[W^(VI)O2(OC6H4O)2] 3, the results show that tungsten(VI) is less active in redox than molybdenum (VI) and that the change of the valence induced by substitution of W(VI) for Mo(V) in EMO2(OC6H40)2]n- does not influence the coordination geometry of the complex anion in which the metal center exhibits distorted octahedral coordination with cis-dioxo catechol. The responses to EPR of complexes 1 and 2 are active but complex 3 is silent,and the UV-vis spectra exhibited by the three complexes are obvious different because of the different electronic configuration between the central Mo(V) and W(VI) ions in the complexes.It is noteworthy that complexes 1 and 2 have the similar EPR signal to flavoenzyme, suggesting that the three complexes have the same coordination geometry feature with the co-factor of flavoenzyme. 相似文献
293.
294.
Synthesis and reactivity of 3-(trichlorogermyl)propanoic acid and 3-(triphenylgermyl) propanoic acid
3-(Trichlorogermyl)propanoic acid (la) reacts with phenylmagnesium bromide in malar ratio 1:4 to give 3-(triphenylgermyl)propanoic acid (2a).In the compounds la and 2a theβ-carboxylic functional group shows some unusual properties when they react with excess of phenylmagnesium bromide.The compound la reacts with phenylmagnesium bromide in molar ratio 1:5 to give phenyl 2-(triphenylgermyl)ethylketone (3a) and in molar ratio 1:6 to give l,l-diphenyl-3-(triphenylgermyl)propanol (4a).The compound 2a reacts with phenylmagnesium bromide in molar ratio 1:2 to give 3a and in molar ratio 1:3 to give 4a also.Dehydration of the compound 4a with dilute hydrochloric acid seems especially easy.Moreover,the compound la reacted with phenylmagnsium bromide in molar ratio 1:6,then the mixture was treated with dilute hydrochloric acid to give 1,1-diphenyl-3-(triphenylgermyl)-1-propene (5a) in one pot reaction.Alkyl Ge-C bond in the compound 5a can be cleaved selectively by lithium aluminium hydride ( LiAlH4) in good yiel 相似文献
295.
Interaction between octahedrally coordinated Nd3+ and Yd3+ in Cs2NaNd0,4Yb0,6Cl6 reduces the Nd3+ luminescence lifetime by roughly two orders of magnitude with respect to that found in Cs2NaNdCl6– · – Analysis of low temperature absorption and emission spectra reveals that the nonradiative Nd3+–Yb3+ energy transfer has to be assisted by lattice phonon emission, nevertheless the rate of the transfer is high in the 4–300 K temperature region and attains 5.8×105s-1 at room temperature. A phase transition of Cs2NaNd0,4Yb0,6Cl6 between 12 and 13 K is evidenced by abrupt change of both the spectra and lifetimes of Yb3+. Reduction of Yb3+ lifetime from 5.3 ms to 150 μs is at the transition from low symmetry phase to high symmetry phase is supposed to be associated with a three ion interaction which occurs in ordered lattice and disappears in low temperature disordered structure. 相似文献
296.
297.
2H-1,2,4-噻二唑并[2,3-a]嘧啶衍生物的合成及除草活性研究(Ⅲ) 总被引:2,自引:3,他引:2
合成了10个新的2-乙氧甲酰亚胺基-2H-1,2,4-噻二唑并[2,3,-a]嘧啶类化 合物,结构经IR,^1H NMR,MS和元素分析确证,除草活性测定结果表明,部分目标 化合物具有良好的除草性且选择性较好,对双子叶植物安全。 相似文献
298.
299.
Rao RN Alvi SN Rao BN;HPLC Group Analytical Chemistry Division 《Journal of chromatography. A》2005,1076(1-2):189-192
A simple and rapid preparative high-performance liquid chromatography (HPLC) method has been developed to isolate and characterize some minor impurities of astaxanthin using a normal-phase Lichrosorb silica column with n-hexane-acetone-tetrahydrofuran (90:2:8, v/v/v) as mobile-phase and detection at 475 nm. The isolated impurities were characterized as astacene, dehydro astacene and apoastaxanthinal by UV-vis, ESI-MS, 1H and 13C NMR spectroscopy and the molecular structures were assigned. The impurities collected using the developed conditions were over 98% pure. 相似文献
300.
Rebeka Nádasdi István Szilágyi Gergely Kovács Sándor Dóbé Tibor Bérces Ferenc Márta 《Reaction Kinetics and Catalysis Letters》2006,89(1):193-199
Summary The fast flow technique with OH resonance fluorescence detection has been applied at T = 298 ± 2 K to study the kinetics of the overall reaction: H + CH3C(O)Cl → products (1) A rate constant value of k1 = (1.02 ± 0.12) x 1010 cm3 mol-1 s-1 has been determined which is the first direct kinetic parameter reported for reaction (1) in the literature (the error given
refers to 2σ accuracy). 相似文献