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971.
聚苯胺对2,5-二巯基-1,3,4-噻二唑氧化还原反应的电化学催化作用的循环伏安研究 总被引:4,自引:0,他引:4
研究了聚苯胺(PAn)膜电极在2,5-二巯基-1,3,4-噻二唑(DMcT)溶液中电化学处理或浸泡后的循环伏安(CV)曲线的变化规律.实验结果表明,PAn膜电极在DMcT溶液中进行电化学处理或浸泡过程可使DMcT进入PAn膜内部与PAn形成复合物.PAn对DMcT的电化学催化作用可能和二者之间形成的电子给体-受体复合物有关.该复合物的电化学氧化还原特性不同于PAn和DMcT,其氧化还原反应速率和可逆性均优于DMcT. 相似文献
972.
用量子化学中的密度泛函DFT方法,在B3LYP/6-311G~*水平上研究了不饱和类 卡宾H_2C=CLiF的结构。结果表明,只有1种平衡结构是稳定的。对稳定的平衡结构 ,找到了分子内氢迁移反应的过渡态,并计算了不同温度下不饱和类卡宾 H_2C=CLiF的平均寿命τ,在200 K时,τ = 7.9 d,在300 K仅为τ = 2.4 s。 相似文献
973.
Results of a quantum-chemical study of the molecular structure of dimerization products of saturated 1,3-butadiene and hexafluoro-1,3-butadiene (tricyclo[3.3.0.02.6]octane, dodecafluorotricyclo[4.2.0.02.5]octane (I), and dodecafluorotricyclo[3.3.0.02.6]octane (II)) are presented. The calculated symmetry of the molecule of I in vacuum (C 2) differs from its symmetry in the single crystal (C b , XRD). The most stable of dimers (II) contains C-C bonds with a length of up to 1.573 Å and a four-atom cycle with angles of 82.3°. 相似文献
974.
Zilu Chen 《Journal of solid state chemistry》2008,181(8):2078-2086
Four Cd(II) and Zn(II) complexes with the in situ-generated ligand of 3-amino-1,2,4-triazolate (AmTAZ−) were isolated from the solvothermal reactions of the corresponding Cd(II) or Zn(II) salts with 5-amino-1H-1,2,4-triazole-3-carboxylic acid (AmTAZAc). Their structures were determined by single-crystal X-ray diffraction analysis. [Zn(AmTAZ)(CH3COO)] (1) presents a two-dimensional framework constructed from Zn(II) ions and μ3-AmTAZ− ligands. A remarkable feature of [Zn4(AmTAZ)4(SO4)(OH)(C2O4)0.5]·2H2O (2) is the construction of the building units of octagonal cylinders which interact with each other by sharing one face or overlapping, resulting in the formation of a three-dimensional framework with three kinds of 1D channels. [Cd(AmTAZ)Br] (3) crystallizes in a chiral space group P212121, giving a homochiral three-dimensional framework with two types of helical channels (left- and right-handed). Different from the others, the 3-amino-1,2,4-triazole molecules in [Cd(AmTAZH)SO4] (4) behave as neutral μ2-2,4-bridges to connect the two-dimensional CdSO4 sheets into a three-dimensional framework. Of all, 2 and 3 display different fluorescent properties probably due to different metal ions, coordination environments and structural topologies. 相似文献
975.
976.
Tevhide Özkaya Abdulhadi Baykal Muhammet Sadaka Toprak 《Central European Journal of Chemistry》2008,6(3):465-469
Water-soluble Mn3O4 nanocrystals have been prepared through thermal decomposition in a high temperature boiling solvent, 2-pyrrolidone. The final
product was characterized with XRD, SEM, TEM, FTIR and Zeta Potential measurements. Average crystallite size was calculated
as ∼15 nm using XRD peak broadening. TEM analysis revealed spherical nanoparticles with an average diameter of 14±0.4 nm.
FTIR analysis indicated that 2-pyrrolidone coordinates with the Mn3O4 nanocrystals only via O from the carbonyl group, thus confining their growth and protecting their surfaces from interaction
with neighboring particles.
相似文献
977.
G. V. Giniyatullina O. B. Flekhter I. P. Baikova Z. A. Starikova G. A. Tolstikov 《Chemistry of Natural Compounds》2008,44(5):603-605
A practical method for preparing methyl 3β-amino-3-dexoybetulinate that is based on column chromatographic separation of 3α- and 3β-t-butoxycarbonates and subsequent removal of the protecting group using formic acid is proposed. The structure of methyl 3β-N-(t-butoxycarbonyl)-3-deoxybetulinate was established by an x-ray structure analysis.
Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 488–490, September-October, 2008. 相似文献
978.
A. S. Mendkovich M. A. Syroeshkin L. V. Mikhalchenko A. I. Rusakov V. P. Gultyai 《Russian Chemical Bulletin》2008,57(7):1492-1495
The protonation of the electrochemically generated (0.1 M solution of tetrabutylammonium perchlorate in DMF) 1,3-dinitrobenzene (1) dianions with phenol, ethanol, tert-butanol, and 1-butyl-3-methylimidazolium cation was studied by cyclic voltammetry and chronoamperometry at the carbositall
working electrode. The rate constants for the protonation (k) of the dianion of compound 1 by phenol, 1-butyl-3-methylimidazolium cation, ethanol, and tert-butanol were estimated by the comparison of the data of cyclic voltammetry and chronoamperometry with the digital simulation
results, being 100, 50, 1.5, and 0.01 L mol−1 s−1, respectively. The similarly obtained k value for the protonation of the dianion of 1,4-dinitrobenzene (2) with phenol is 13 L mol−1 s−1. According to the quantum chemical calculation results, the protonation of the dianions of compounds 1 and 2 with phenol and 1-butyl-3-methylimidazolium cation can be classified as orbital-controlled reactions.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1463–1466, July, 2008. 相似文献
979.
Filippi A Speranza M Paladini A De Carolis R Guidoni AG Laganà A Satta M 《Journal of mass spectrometry : JMS》2006,41(1):98-102
Diastereomeric clusters of general formula [MAB(2)](+) and [MA(2)B](+) (M = Li(I), Na(I), Ag(I), Ni(II)-H, or Cu(II)-H; A = (R)-(-)- and (S)-(+)-(1-aminopropyl)phosphonic acid; B = (1R)-(-)- and (1S)-(+)-(1-aminohexyl)phosphonic acid) have been readily generated in the electrospray ionization (ESI) source of a triple-quadrupole mass spectrometer and their collision-induced dissociation (CID) investigated. CID of diastereomeric complexes, e.g. [MA(S)(B(S))(2)](+) and [MA(R)(B(S))(2)](+), leads to fragmentation patterns characterized by R(homo) = [MA(S)B(S)](+)/[M(B(S))(2)](+) and R(hetero) = [MA(R)B(S)](+)/[M(B(S))(2)](+) abundance ratios, which depend upon the relative stability of the diastereomeric [MA(S)B(S)](+) and [MA(R)B(S)](+) complexes in the gas phase. The chiral resolution factor R(chiral) = R(homo)/R(hetero) is found to depend not only on the nature of the M ion but also on that of the fragmenting species, whether [MAB(2)](+) or [MA(2)B](+). The origin of this behavior is discussed. 相似文献
980.
Fructosamine-3-kinase (FN3K) mediates the regeneration of lysine from fructosamines formed on proteins as a result of the
‘early’ Maillard reaction. As fructosamines and advanced glycation endproducts derived therefrom are supposed to play an adverse
role in the development of diabetic complications, FN3K is discussed as a protein-repairing enzyme. In this study, a method
for the determination of FN3K activity in erythrocyte lysate is described which overcomes the complexity of currently known
assays. The assay is based on the FN3K-dependent conversion of the synthetic UV-active fructosamine N
α-hippuryl-N
ε-(1-deoxy-D-fructosyl)lysine (BzGFruK) to N
α-hippuryl-N
ε-(phosphofructosyl)lysine (BzGpFruK). The FN3K activity was quantified by measuring the formation of BzGpFruK using RP-HPLC
with UV detection. Identification of the metabolite BzGpFruK was achieved by means of UV and mass spectroscopy. The results
are related to the content of haemoglobin for standardisation. First activity measurements with a chosen number of normoglycaemic
subjects confirmed the convenient applicability of the method and showed distinctly different individual activities, as already
discovered recently. The new established assay needs only the equipment of a routine laboratory with HPLC instrumentation.
This should facilitate further studies about a possible relationship between the FN3K activity and the development of diabetic
complications. 相似文献