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921.
Effect of matrix physical characteristics on the reactivity and reaction pathways of organic radical cations in ground and
excited states in solid phase is considered. The analysis of the results obtained using solid rare gas matrices (argon, krypton,
and xenon) showed the ionization potential and polarizability of the matrix to determine to a considerable extent the fate
of organic radical cations resulting from charge transfer. In some cases, the matrix control of this kind may lead to nearly
complete “switching” between the reaction channels upon changing one inert matrix for another. Data on the mechanism and efficiency
of the reactions of electronically excited radical cations in solid phase (freons, sulfur hexafiuoride) were analyzed. It
was shown that the matrix effects also had strong influence on the selection of specific reaction pathways and their efficiency
in this case 相似文献
922.
I. T. Bazyl’ S. P. Kisil’ Ya. V. Burgart V. I. Saloutin 《Russian Journal of Electrochemistry》2000,36(6):904-909
The derivatives of 4-hydroxy-5,6,7,8-tetrafluorocoumarin in reactions witho-aminothiophenol yield products of S-substitution at C7 atom, 7-substituted 5,6,8-trifluorocoumarins afford benzothiazoles as a result of cleavage of the pyrone cycle, 2-methyl-3-ethoxycarbonyl-5,6,7,8-tetrafluorochromone
undergoes acidic cleavage to 2-(2-hydroxy-3,4,5,6-tetrafluorophenyl)benzothiazole. S-Substituted coumarins in alkaline media
suffer decomposition to acetophenone. In acidic media 3-iminoacetyl-4-hydroxy-5,6,8-trifluoro-7-(2-aminophenylthio)coumarin
affords 2-methyl-5,6,8-trifluoro-7-(2-aminophenylthio)chromone. In condensation of 4-hydroxy-5,6,8-trifluoro-7-(2-aminophenylthio)coumarin
in the presence of NaH was isolated 4-hydroxy-5,6-difluoro-2H-pyrano[6,5-a]phenothiazin2-one. 相似文献
923.
V. S. Reznik Ya. A. Levin V. D. Akamsin I. V. Galyametdinova R. I. Pyrkin 《Russian Chemical Bulletin》2000,49(3):495-498
Primary alkylamines, β-aryloxyethylamines, orN-[β-(2-methoxyphenoxy)ethyl]-α,ω-diaminoalkanes react with alkyl divinyl phosphinates or phenyl(divinyl)phosphine oxide to give the corresponding 4-alkoxy(4-phenyl)-1-alkyl-4-oxo-1,4-azaphosphorinanes. Reactions of the latter with mono- or dihaloalkanes afford 4-phosphapiperidinium halides. 1,4-Azaphosphorinanes containing a β-aryloxyethyl fragment exhibit hypotensive activity. 相似文献
924.
Lanthanum, neodymium, and samariumtert-butoxycuprates [(ButO)5Cu2Ln]2 were synthesized in high yields by reactions of ButOCu with lanthanide metals, the halides Sml2 and LnX3 (Ln=La, Nd: X=Cl, 1) and by the reaction of ButOLi with a mixture of LnCl3 and CuCl. X-Ray diffraction analysis showed that the structure of [(ButO)5Cu2Sm]2 is based on octahedra formed by four copper atoms in equatorial positions and two samarium atoms in axoal positions; the copper and samarium atoms are linked by μ3-bridging ButO groups. The reactions of lanthanumtert-butoxycuprate with H2O, HCl, CpH, PhC≡CH, and CO2 were studied. 相似文献
925.
Ya. I. Korenman E. S. Rudnichenko E. I. Mel’nikova S. I. Niftaliev 《Russian Journal of Applied Chemistry》2008,81(9):1597-1601
A multisensor system based on an array of weakly selective sensors was used to determine organic odor-producing substances in gas mixture. As modifiers of electrodes of mass-metric piezoelectric resonators served polyethylene glycol esters (succinate, phthalate), tris(hydroxymethyl)aminomethane, N-methyl-2-pyrrolidone, polyphenyl ether, sodium nitroprusside, sulfosalicylic and ribonucleic acids, and diphenylcarbazide. For the example of a biotechnological object, true milk solution, visual “patterns” of odor-producing components were constructed. Their type is determined by the sensitivity of the sensors and is independent of the concentration of the substances under study. 相似文献
926.
5,6,7,8-Tetrafluoro-4-hydroxycoumarin reacted with benzylamine under mild conditions to give a stable salt, while its refluxing
with aniline or benzylamine in xylene afforded 5,6,7,8-tetrafluoro-4-phenyl(benzyl)aminocoumarins. Reactions of 3-acetyl(acetimidoyl)-5,6,7,8-tetrafluoro-4-hydroxycoumarins
with benzylamine followed different pathways, depending on the solvent. Condensation at the acyl substituent can be accompanied
by replacement of the F atom in position 7. 3-Acetylcoumarin formed a salt, while 3-acetimidoylcoumarin yielded a 7-monosubstituted
product. 3-Acetyl(acetimidoyl)-5,6,7,8-tetrafluoro-4-hydroxycoumarins reacted with aniline to give only 5,6,7,8-tetrafluoro-4-hydroxy-3-(N-phenylacetimidoyl)coumarin.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1170–1174, July, 2006. 相似文献
927.
超大硅胺基取代的低价锗化合物可以构建新颖的化学结构,提供有学术价值的新发现。二配位的超大硅胺基氯锗宾Ge(N(SiiPr3)2)Cl (1)具有空的4p轨道和孤电子对。针对这2个特点,研究了化合物1的热构型转换和菲醌氧化加成反应。1的温热分解生成了立方四锗卡宾 Ge4(NSiiPr3)4 (2),与菲醌(L)定量氧化加成生成了胺基一氯菲二酚合锗(Ⅳ):[Ge(N(SiiPr3)2)(L)Cl] (3)。表征了2个产物的单晶结构与组成。四锗卡宾2本质上是锗异腈的四聚体,分子呈现出畸变的立方体构型,4个Ge原子和4个N原子构成了中心立方体的 8个顶点。其中 Ge—N键长为 0.203 6(3) nm,N—Ge—N与 Ge—N—Ge的键角分别为 85.51(18)°和94.32(16)°,立方体的侧面接近平行四边形。理论计算首次揭示了四锗卡宾2的成键面貌。自然键轨道(NBO)给出Ge4N4骨架上的20个分子轨道。轨道定域化的计算结果完好地呈现出4对Ge孤对电子、12个Ge—N键和4个Si—N键的定域轨道,能量分别为-12.22、-15.12 和-20.12 eV。Ge 孤对电子主要保留了 4s 电子的特性,而 Ge—N 键主要由 N 的 2s 轨道(18.4%)和 2p 轨道(71.3%)、Ge的4s轨道(0.75%)和4p轨道(9.43%)综合贡献形成。在化合物3的分子中,GeⅣ采取sp3杂化,由于空间位阻与非对称配位,与另外4个配位原子形成非对称四面体构型。 相似文献
928.
Jiehao Du Banggui Cheng Huiqing Yuan Yuan Tao Ya Chen Mei Ming Zhiji Han Richard Eisenberg 《Angewandte Chemie (International ed. in English)》2023,62(9):e202211804
We report the unprecedented electrocatalytic activity of a series of molecular nickel thiolate complexes ( 1 – 5 ) in reducing CO2 to C1–3 hydrocarbons on carbon paper in pH-neutral aqueous solutions. Ni(mpo)2 ( 3 , mpo=2-mercaptopyridyl-N-oxide), Ni(pyS)3− ( 4 , pyS=2-mercaptopyridine), and Ni(mp)2− ( 5 , mp=2-mercaptophenolate) were found to generate C3 products from CO2 for the first time in molecular complex. Compound 5 exhibits Faradaic efficiencies (FEs) of 10.6 %, 7.2 %, 8.2 % for C1, C2, C3 hydrocarbons respectively at −1.0 V versus the reversible hydrogen electrode. Addition of CO to the system significantly promotes the FEC1–C3 to 41.1 %, suggesting that a key Ni−CO intermediate is associated with catalysis. A variety of spectroscopies have been performed to show that the structures of nickel complexes remain intact during CO2 reduction. 相似文献
929.
Seda Ünlü Göknur Yaşa Atmaca Fikriye Tuncel Elmalı Ali Erdoğmuş 《Photochemistry and photobiology》2023,99(5):1233-1239
Although the sonophotodynamic method has an effective therapeutic outcome for anticancer treatment compared with the photodynamic method, there are not enough related studies in the literature and this study aims to contribute to the development of sonophotodynamic studies. For this purpose, the Schiff base substituted silicon phthalocyanines were designed and synthesized as effective sensitizer candidates and the photophysicochemical and sonophotochemical features of the phthalocyanines were examined to increase singlet oxygen efficiency. The calculated ΦΔ values indicate that the contribution of substituent groups improved the production of singlet oxygen compared with silicon (IV) phthalocyanine dichloride (SiPcCI2) and also the sonophotochemical applications increased the singlet oxygen yields. The ΦΔ values (ΦΔ = 0.76 for axially bis-{4-[(E)-(pyridin-3-ylimino)methyl]phenol} substituted silicon (IV) phthalocyanine ( 2a ), 0.68 for axially bis-4-[(E)-{[(pyridin-3-yl)methyl]imino}methyl]phenol substituted silicon (IV) phthalocyanine ( 2b ) in photochemical study) reached to ΦΔ = 0.98 for 2a , 0.94 for 2b in sonophotochemical study. This article will enrich the literature on increasing singlet oxygen yield. 相似文献
930.
Capillary zone electrophoresis (CZE) has been applied for fractionation and characterization of soil-derived humic acids (HAs). Humic acids from soddy-podzolic (HA(s)) and chernozem (HA(ch)) soils were studied as well as hydrophobic high-molecular-weight (HMW) and hydrophilic low-molecular-weight (LMW) HA(s) fractions obtained by salting-out with ammonium sulfate at a saturation of 0-40% and >70%, respectively. The possibility of CZE partial fractionation of HAs has been demonstrated. The shape of "humic hump" was shown to depend on the pH of running electrolyte. Almost the whole peak overlapping occurred if alkaline solutions were used for fractionation, but the peak resolution was improved at pH 5-7. Under appropriate fractionation conditions (pH 7), at least three humic acid subfractions with different electrophoretic mobilities were distinguished in the electropherograms of initial HA and HA(s) fractions. Such a high peak resolution has never been achieved for humic acids before. The presence of three subfractions in the HA is in agreement with gel-filtration analysis and was confirmed by comparison of the electrophoretic behavior of HA(s) with those of its HMW (hydrophobic) and the LMW (hydrophilic) fractions. The potentiometric titration of HA and its fractions was performed and the pK(a) of the functional groups were calculated. An attempt was made for the first time to relate the variation of electrophoretic mobility values with acid-base properties of humic acids. It was shown that changes in the humate charge resulting from the variation of the ionization degree of its functional groups as a function of pH can be estimated on the basis of electrophoretic mobility values. Potential of CZE in estimation of HA isoelectric point was demonstrated. The pH value corresponding to the lowest absolute electrophoretic mobility value of about 20 x 10(-5) cm(2) V(-1) s(-1) can be used for approximate estimation of HA isoelectric point. The data were discussed and agreement with the random coil structural model has been shown. 相似文献