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941.
Aikins JA Haurez M Rizzo JR Van Hoeck JP Brione W Kestemont JP Stevens C Lemair X Stephenson GA Marlot E Forst M Houpis IN 《The Journal of organic chemistry》2005,70(12):4695-4705
The stereospecific synthesis of the PPAR alpha/gamma agonist 1 was accomplished via ethylation of the optically pure trihydroxy derivative 6, itself derived via an enzymatic resolution. The ethylation can be accomplished without epimerization only under strict control of the reaction conditions and the choice of base (sodium tert-amylate), temperature (-30 degrees C), order of addition, and solvent (DMF). The key diastereospecific SN2 reaction of the phenol 4 with S-2-chloropropionic acid is best achieved via the sodium phenoxide of 4 derived from Na0 as the reagent of choice. The structure elucidation and key purification protocols to achieve pharmaceutical purity will also be described. 相似文献
942.
Erich Dubler Lothar Linowsky Jean-Pierre Matthieu Hans-Rudolf Oswald 《Helvetica chimica acta》1977,60(5):1589-1600
Synthesis, crystal structure and thermal dehydration of CsMnF4 · 2H2O The preparation of a new fluoromanganate (III)-complex CsMnF4 · 2H2O is reported. It crystallizes in the monoclinic space group C2 with a = 11.891(2) Å, b = 6.589(1) Å, c = 10.558(1) Å, β = 131.46(1)° and Z = 4. The crystal structure has been solved from diffractometer data by heavy-atom methods and refined to a conventional R-value of 1.8% (including the contributions of three hydrogen atoms in measured and one in calculated positions). The structure is characterized by isolated, tetragonally distorted [MnF4(OH2)2]-octahedra with Mn-F-distances from 1.801(8) Å to 1.870(7) Å and Mn-O-distances of 2.146(6) Å and 2.268(6) Å. Cesium exhibits an irregular 10-coordination by 8 F-atoms and 2 O-atoms (mean values for the two independent cesium ions: Cs-F = 3.17 Å and 3.21 Å, Cs-O = 3.32 Å and 3.29 Å). The [MnF4(OH2)2]-octahedra are connected to six neighbouring octahedra by hydrogen bonding. The dehydration of the complex has been studied by thermoanalytical methods and power x-ray-diffractometry. The unit cell of the dehydrated compound, CsMnF4, is tetragonal with a = 7.936(1) Å and c = 6.341(1) Å. A close relationship to the structure of CsFeF4, which is a superstructure variant of the T1A1F4-type[6], is indicated by the similarity of the corresponding unit cells and preliminary structure factor calculations. A proposition for the crystal structure of CsMnF4 is developed on the basis of (2 + 2 + 2)-orthorhombic distorted MnF6-octahedra. 相似文献
943.
Jean-Pierre Denhez Michle Ricard Madeleine Corval 《Journal of mass spectrometry : JMS》1976,11(3):258-265
The fragmentation patterns of two paris of heterocycil compounds are investigated in order to discuss the effect of the nature of the heteroatom. 相似文献
944.
In order to evaluate more deeply the nature of the activation of oxirane ring opening reactions by HFIP, ring opening of both CF3-epoxy ethers 1a (R = Ph) and 1b (R = CH2CH2Ph) with HFIP alone, and with hard (MeOH) or soft (PhSH) nucleophiles in HFIP, were investigated and compared to reactions performed with Brönsted acids. Nucleophilic ring opening reactions in HFIP were facilitated with PhSH and only α-substituted trifluoromethyl ketone 5 was isolated (nucleophilic ring opening), while with MeOH, both processes, nucleophile and electrophile-assisted ring opening were in competition. In the Brönsted acid-catalysed ring opening of 1-CF3-epoxy ethers 1 in HFIP, only the acid-catalysed ring opening process occurred with an inversed regioselectivity. 相似文献
945.
Terazzi E Torelli S Bernardinelli G Rivera JP Bénech JM Bourgogne C Donnio B Guillon D Imbert D Bünzli JC Pinto A Jeannerat D Piguet C 《Journal of the American Chemical Society》2005,127(3):888-903
The connection of lipophilic gallic acid derivatives at the 5,5'- or 6,6'-positions of the rigid 2,6-bis(1-ethyl-benzimidazol-2-yl)pyridine core provides two pro-mesogenic tridentate ligands L10 and L12, whose molecular shapes, anisometries, and directional intermolecular pi-stacking can be tuned. X-ray diffraction data in the crystalline state, combined with solution 1H NMR measurements, show that complexation with trivalent lanthanides, Ln(III), produces the neutral hemi-disklike complexes [Ln(Li)(NO3)3] (i = 10, 12), which dimerize to give the rodlike bimetallic complexes [Ln2(Li)2(NO3)6] at lower temperature. The relevant thermodynamic parameters for the latter process depend on the nature of the ligand, the size of the metal ion, and the strength of the intermolecular interactions involved in the condensed phase. These three-dimensional models obtained for the complexes in the crystals and in solution are eventually confronted with small-angle XRD profiles recorded in the intermediate thermotropic liquid crystalline phase, in which the rigidity of the packed polyaromatic cores is maintained, while the alkyl chains are molten. According to the specific geometries and nuclearities of the molecular complexes, three types of mesophases (lamellar, columnar, and cubic) can be induced, which provides a direct correlation between the microscopic arrangements and the macroscopic ordering in lanthanide-containing metallomesogens. 相似文献
946.
The viscosities of binary alkali halide-water systems and of ternary alkali halide-tert-butyl alcohol-water systems have been measured at 25°C in the water-rich region. The relative viscosities of the ternary solution are expressed by an extended form of the Jones-Dole equation $$\begin{gathered} \eta /\eta _0 = 1 + {\text{A}}_E {\text{m}}_E^{1/2} + {\text{B}}_E {\text{m}}_E + {\text{B}}_N {\text{m}}_N + {\text{D}}_{EE} m_E^2 \hfill \\ + {\text{D}}_{NN} {\text{m}}_N^2 + {\text{D}}_{EN} {\text{m}}_E {\text{m}}_N + ... \hfill \\ \end{gathered} $$ wherem E andm N are the molalities of the electrolyte E and nonelectrolyte N expressed in mole-kg?1 of water. The parameterA E accounts for the long-range ionic forces, andB E andB N are the Jones-DoleB coefficients of E and N. It is shown, in particular, that theD EN term is additive for different ionic pairs and that it can be correlated to the entropic coefficient of pair interaction. TheD EN coefficients thus seem to reflect some pair interaction contribution to the excess viscosity of ternary mixtures. 相似文献
947.
Duy H Hua Xiaodong HuangMasafumi Tamura Yi ChenMelissa Woltkamp Lee-Way JinElisabeth M Perchellet Jean-Pierre PerchelletPeter K Chiang Ichiji NamatameHiroshi Tomoda 《Tetrahedron》2003,59(26):4795-4803
In search of compounds that ameliorate the toxicity of amyloid-β (Aβ) peptides, new derivatives of tricyclic pyrones (1-7) were synthesized and their biological activities evaluated. The carboxylic ester and amide derivatives 1-4 were synthesized from a selective carboxylation of C3 methyl of (5aS,7S)-{7-Isopropenyl-3-methyl-1H,7H-5a,6,8,9-tetrahydro-1-oxopyrano[4,3-b][1]benzopyran (8) with LDA followed by benzyl chloroformate or carbon dioxide to provide ester 1 and carboxylic acid 9, respectively. Three isomeric tricyclic pyrone, 5-7, containing adenine moiety at C7 side chain were synthesized from the alkylation of mesylate 13 with adenine, and displacement of chloropurine 15 with amine 14. Although C3-benzyloxycarbonylmethyl analogs 1-3 have marginal ACAT and CETP activities, their modified aspartate analog 4 and C3-methyl-C7-(N3-adeninyl)-2-propyl analog 6 show a significant effect in protecting against neuron-cell death from the toxicity of intracellular accumulation of Aβ or Aβ-containing C-terminal fragments (CTF) of amyloid β precursor protein (APP). N9-Adenine analog 5 is 20-fold less effective than N3-adenine derivative 6 in the protection of neuron-cell death induced by Aβ, while N10-adenine analog 7 was inactive. As a result of this study, compounds 4 and 6 will well serve as lead compounds for further studies of the mechanism of action of Aβ-and CTF-induced neuron-cell death, studies which should enhance the future development of new drugs for the prevention and treatment of AD. 相似文献
948.
Samira El Ghammarti Benoit Rigo Hechmi Mejdi Jean-Pierre Hnichart Daniel Couturier 《Journal of heterocyclic chemistry》1998,35(3):555-565
Pyroglutamic acid was transformed into 1-[(N-Acetylarylamino)methyl]pyroglutamic acid derivatives by using trimethylsilyl variations of the Mannich reaction. 相似文献
949.
950.
Pharmacokinetics of Tetra (m-hydroxyphenyl)chlorin in Human Plasma and Individualized Light Dosimetry in Photodynamic Therapy 总被引:2,自引:0,他引:2
Thomas Glanzmann Christophe Hadjur Matthieu Zellweger Pierre Grosjean Martin Forrer Jean-Pierre Ballini Philippe Monnier Hubert van den Bergh Chang Kee Lim Georges Wagnières 《Photochemistry and photobiology》1998,67(5):596-602
The pharmacokinetics of the photosensitizer 5,10,15,20-tetra( m -hydroxyphenyl) chlorin(mTHPC) was investigated in the plasma of 20 patients by absorption and fluorescence spectroscopy. The temporal behavior was characterized by a rapid decrease in concentration during the first minutes after intravenous injection of 0.15 mg/kg mTHPC. A minimum concentration in the plasma was reached after about 45 min. The drug concentration then increased again, attaining a maximum after about 10 h, after which it decreased again with a halflife of about 30 h. Irradiation tests in the oral cavity at different time intervals after the injection revealed that the tissue re-action was only partially correlated with the mTHPC plasma level. The tissue response was stronger at later drug-light intervals (1–4 days) than during the first hours after injection even though the mTHPC plasma concentration was higher at the shorter times. Relative mTHPC concentrations were also measured in the mucosae of the oral cavity, the esophagus and the bronchi of 27 patients by light-induced fluorescence spectroscopy using an optical fiber-based spectrometer. These measurements were performed prior to photodynamic therapy (PDT), 4 days after injection of the photosensitizer. Highly significant linear correlations were found between the relative mTHPC concentrations in the mucosae of these three organs. Likewise, the plasma levels of mTHPC measured just before PDT were significantly correlated with the mTHPC concentrations in the three types of mucosae mentioned above. These results indicate that mTHPC plasma levels measured just before PDT can be used for PDT light dosimetry. 相似文献