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891.
The preparation of some new tetrakis[bis(pentafluorophenyl)methoxyl] substituted metal free and metallophthalocyanine (MPcs) complexes were achieved by the tetramerization of 4-[bis(pentafluorophenyl)methoxy]phthalonitrile with Li metal in pentan-1-ol or metal [Co(II) or Zn(II)] acetates in DMAE, respectively. The structures of the target compounds were confirmed by elemental analysis, IR, UV–vis, 1H NMR, 19F NMR and mass spectroscopic methods. MPcs are soluble only in strong and medium polar solvents while the metal free one is soluble in weakly, medium and strong polar solvents. The temperature and frequency dependence of the electrical conductivities were studied on spin coated films of the compounds using dc and impedance spectroscopy techniques in the frequency range from 40 to 105 Hz and within the temperature range from 290 to 440 K. The temperature dependence of the exponent s and conductivity, σac, were completely in agreement with the prediction of the hopping model. The redox properties of the complexes were determined by cyclic voltammetry. The nature of the redox processes was also confirmed using spectroelectrochemical measurements. 相似文献
892.
Diazomethyl ketones (2-diazoethanones) were reacted with the Vilsmeier reagent ((chloromethylidene)dimethylammonium chloride) to yield α-diazo-β-oxoaldehydes and chloromethyl ketones. 2′,4′-Dimethoxy-α-diazoacetophenone gave 2-chloro-1-(2,4-dimethoxyphenyl)-3-(dimethylamino)prop-2-en-1-one ( 5 ) in addition to the expected products. Phenyldiazomethanes gave the corresponding benzyl chlorides but not the (phenyl)diazoacetaldehydes even at temperatures as low as ?60°. The diazo-transfer reactions of phenylacetaldehydes and 2-azido-1-ethylpyridin-1-ium tetrafluoroborate also did not yield the expected(phenyl)diazoacetaldehydes. 相似文献
893.
Kaya Imre George Odian Abdelgewad Rabie 《Journal of polymer science. Part A, Polymer chemistry》1976,14(12):3045-3066
The quantitative effect of diffusion control on the rate of radiation-initiated graft polymerization has been studied theoretically for systems in which the diffusion-free reaction may show various dependencies of rate on monomer concentration other than the usual first-order dependence. The study is also very general in that it can be applied to systems involving a variety of different modes of initiation and termination. Whether the grafting process is diffusion-free or diffusion-controlled has been analyzed in terms of the interaction of the initiation rate Ri, the propagation and termination rate constants kp and kt, the equilibrium solubility M of the monomer in the polymer, the polymer film thickness L, the diffusivity D of the monomer in the polymer, and the diffusion-free kinetic order of dependence v of the grafting rate on monomer concentration. The dependence of the grafting rate for both the diffusion-free and diffusion-controlled reactions on these parameters is expressed both by mathematical experssions and graphically. Diffusion control is shown to occur at a critical value of the parameter A which is proportional to L(kpRiw/ktzD)1/2M(ε?1)/2 where w, z, and v have different values depending on the specific modes of initiation, propagation and termination in a particular grafting system. The grafting rate is shown to vary with the value of A according to specific mathematical expressions. In comparing diffusion-free to diffusion-controlled reaction, it is shown that the former is independent of L and D while the latter is directly dependent on L and inversely on D1/2. Further, the change from diffusion-free to diffusion-controlled reaction involves a change in the dependence of rate on monomer from v-order to [(v ? 1)/2]-order. The nonsteady-state as well as the steady-state reaction rates have been analyzed. 相似文献
894.
Asu Usta Ahmet Yaşar Nagihan Yılmaz Canan Güleç Nuran Yaylı Şengül Alpay Karaoğlu Nurettin Yaylı 《Helvetica chimica acta》2007,90(8):1482-1490
Nine new thiazachalcone‐based drugs, compounds 1 – 9 , were prepared and fully characterized. The configurations of the photochemical‐dimerization products 7 – 9 were rationalized by semi‐empirical calculations. Both the experimental data and the theoretical calculations showed that the δ‐truxinic acid type dimer is the most stable isomer of all. All compounds were tested for their antibacterial and antifungal activities. The N‐alkylated congeners 4 – 6 showed strong antimicrobial activities against various bacteria and a yeast‐like fungus. The MIC and MBC values were as low as 0.1 μg/ml. All the compounds were active against the Gram‐positive bacterium Staphylococcus aureus. 相似文献
895.
4‐Ethoxycarbonyl‐5‐phenyl‐2,3‐dihydrofuran‐2,3‐dione 1 reacts with aldehydes via the acylketene intermediate 2 giving the 1,3‐dioxin‐4‐ones 3a‐e and the 1,4‐bis(5‐ethoxycarbonyl‐4‐oxo‐6‐phenyl‐4H‐1,3‐dioxin‐2‐yl)benzene 4 , and a one step reaction between dibenzoylmethane and oxalylchloride gave 3,5‐dibenzoyl‐2,6‐diphenyl‐4‐pyrone 7 . The reaction of 1 with dibenzoylmethane, a dicarbonyl compound, provided ethyl 3‐benzoyl‐4‐oxo‐2,6‐diphenylpyran‐5‐carboxylate derivative 9 . Compound 9 was converted into the corresponding ethyl 3‐benzoyl‐4‐hydroxy‐2,6‐diphenylpyridine‐5‐carboxylate derivative 10 via its reaction with ammonium hydroxyde solution in 1 ‐butanol. 相似文献
896.
We have investigated the elusive reactive species of cytochrome P450(cam) (Compound I), the hydroxo complex formed during camphor hydroxylation, and the ferric hydroperoxo complex (Compound 0) by combined quantum mechanical/molecular mechanical (QM/MM) calculations, employing both density functional theory (DFT) and correlated ab initio methods. The first two intermediates appear multiconfigurational in character, especially in the doublet state and less so in the quartet state. DFT(B3LYP)/MM calculations reproduce the relative energies from correlated ab initio QM/MM treatments quite well, except for the splitting of the lowest A(1u)-A(2u) radical states. The inclusion of dynamic correlation is crucial for the proper ab initio treatment of these intermediates. 相似文献
897.
F. Nazli Dınçer Kaya Ingrid Svoboda Orhan Atakol Ümıt Ergun Adnan Kenar Musa Sari Kaan C. Emregül 《Journal of Thermal Analysis and Calorimetry》2008,92(2):617-624
Six nickel(II) complexes, using azide and thiocyanate ions, have been synthesized from bis-2,6(pyrazol-1-yl)pyridine (pp) and some methyl derivatives, 2-(3,5-dimethyl(pyrazol-1-yl)-6-(pyrazol-1-yl)pyridine (app) and bis-2,6(3,5-dimethyl(pyrazol-1-yl) pyridine (dmpp) in non-aqueous media. The complex structures were analyzed using elemental analysis, IR spectroscopy and thermogravimetry. Appropriate crystals of complex, containing azide [Nipp(N3)2]·MeOH (I) and thiocyanate [Nidmpp(SCN)2·MeOH] (VI) were prepared and the molecular structures determined using X-ray diffraction. Complex I was seen to be dinuclear as stated in literature, space group P21/n, monoclinic, a=10.503, b=10.681, c=13.291 Å, β=106.56° and Z=2 whereas complex VI was found to be mononuclear, space group P21/n, monoclinic, a=8.646, b=12.614, c=20.697 Å, β=97.18° and Z=2. The Ni(II) coordination in both complexes were octahedral. Thermogravimetric studies showed azide containing structures to resemble the characteristics of explosive materials. Coordinative MeOH were seen to leave the structure in thiocyanate containing complexes, followed by irregular degradation above 300°C. 相似文献
898.
A certified reference material (CRM) for microcystins has been prepared by the National Institute for Environmental Studies
(NIES). Microcystins are hepatotoxic cyclic peptides produced by cyanobacteria in eutrophic water bodies. At least seven microcystin
variants were found by HPLC analysis of the NIES CRM, of which [Dha7]microcystin-RR and -LR were the major microcystins present. Because of the lack of available standards we determined the
total microcystin concentration in the CRM by the MMPB method, and elucidated the structures of the main individual microcystin
variants following their isolation. Analyses of NMR and MS spectra indicated that the remaining minor variants in the CRM
were [D-Asp3, Dha7]microcystin-RR and -LR, and [Dha7]microcystin-YR, -ThTyrR, and -HilR. The CRM is valuable not only as a standard material for the quantitation of total microcystins
but also for the identification of individual [Dha7]microcystin variants. 相似文献
899.
A one-dimensional diagonal tight binding electronic
system with dichotomic correlated disorder is investigated. The
correlation of random potential exponentially decays with distance
and also with the dichotomic correlation parameter λ.
Using a appropriate approximation, an analytical transmission
coefficient expression is obtained. The obtained analytical
expression is then tested against the result of the direct
numerical computation of the average transmission coefficient
〈T〉 for the Anderson model, by changing the system parameters. In the thermodynamic limit the transmission coefficient relation
indicates the absence of localization-delocalization transition, which is entirely consistent with numerical predictions. 相似文献
900.
Vildan Sanko Ahmet Şenocak Süreyya Oğuz Tümay Taşkın Çamurcu Erhan Demirbas 《Electroanalysis》2022,34(3):561-572
A novel enzymatic electrochemical biosensor (mCuF/PANI-nf/HA/Lacc/GCE) was designed for detection of bisphenol A (BPA). The copper ferrite nanoparticles was obtained by co-precipitation and its surface was modified with -NH2 functional organosilane. Polyaniline nanofibers were also synthesized by cyclic voltammetry and characterized by FTIR, XRD, TGA, SEM and TEM, respectively. Then, it was crosslinked with hyaluronic acid as an immobilization matrix for Laccase to adhere to surface of the modified copper ferrites. Cyclic and differential pulse voltammetries were used to evaluate the electrochemical performances of the biosensor, which has a LOD value of 5.40 nM and a LOQ value of 16.20 nM in the 0.01–7.50 μM linear working range. The biosensor was successfully applied for determination of BPA in seawater, canned water and milk samples with recoveries ranging from 96.0 % and 100.7 %. In addition, accuracy of the voltammetric determination method in the real samples was carried out by HPLC and spike/recovery test. The layer-by-layer surface modification strategy of the designed mCuF/PANI-nf/HA/Lacc/GCE biosensor opens a new perspective on both BPA determination and using biopolymer in the structure of enzymatic electrochemical biosensors. 相似文献