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排序方式: 共有1882条查询结果,搜索用时 15 毫秒
41.
The novel bis(cyclohexylaminium) cyclohexylaminebis(orotate–N,O)cuprate(II) dihydrate, (C6H15N)2[Cu(C5H2N2O4)2(C6H14N)] · 2H2O, has been prepared and characterized by elemental analysis, magnetic measurements, FT-IR and UV–Vis spectroscopy, thermal analysis and X-ray diffraction. The Cu(II) complex crystallizes in the monoclinic space group P21/c. The copper atom in the five-coordinated (chaH)2[Cu(HOr–N,O)2(cha)] · 2H2O is chelated by a deprotonated pyrimidine nitrogen atom and carboxylate oxygen atom as a bis(bidentate) ligand and the cyclohexylamine ligand completes the square-pyramidal coordination. The thermal decomposition of the complex has been predicted by the help of thermal analysis (TG, DTG and DTA). 相似文献
42.
Several reactions of 2-naphthol with 2-alkyl-2-hydroxymethylaldehydes have been investigated. Novel synthesis of 14-(hydroxymethyl)alkyldibenzo[a,j]xanthenes and 3,3-dimethyl-4-(2-hydroxy-1-naphthyl)benzo[f]chroman has been realized. 相似文献
43.
H. Göktürk C. Eylem S. Hatipoĝlu H. N. Erten 《Journal of Radioanalytical and Nuclear Chemistry》1995,198(2):449-456
The sorption behavior of strontium and barium on kaolinite, bentonite and chlorite-illite mixed clay was studied by radioanalytical techniques using the batch method.90Sr (29.1 y) and133Ba (10.5 y) were used as radiotracers. Characterization of the solid matrices was done by FTIR and XRD spectrometries and specific surface area measurements. Synthetic groundwater was used as the aqueous phase. The variation of the distribution ratioR
d, as a function of metal ion loading was examined. The sorption isotherms were fitted to various isotherm models. The sorption energies were calculated to be in the range of 8–10 kJ/mol suggesting an ion exchange type of sorption mechanism. In detailed experiments, chlorite-illite mixed clay was first presaturated with K+, Sr2+, Ca2+ and Al3+ ions, respectively, prior to sorption studies with Ba2+ ions. The results of Ca2+ pretreated chlorite-illite were very similar to those of natural chlorite-illite, suggesting that the Ba2+ ion exchanges primarily with the Ca2+ ion on the clay minerals. 相似文献
44.
Yunyu Yi Ronald Neufeld Selim Kermasha 《Journal of Sol-Gel Science and Technology》2006,38(3):251-259
Entrapment of membrane proteins is a challenging task compared to that involving soluble proteins. Chlorophyllase, a membrane
protein, was successfully entrapped in tetramethoxysilane-derived sol-gel. Pre-gel sol typically consists of an aqueous suspension
of chlorophyllase, precursors including tetramethoxysilane and/or methytrimethoxysilane, and sodium fluoride as catalyst.
To obtain a highly active entrapped enzyme preparation, the effects of various immobilization parameters, including the chemical
compositions of pre-gel sol (water/silane ratio, precursor type and proportions, enzyme loading, sodium fluoride concentration),
and sol-gel process parameters (aging and drying time and approach) have been investigated. Chlorophyllase demonstrated the
highest activity in gel derived from a pre-gel sol with water/silane ratio of 30 and enzyme loading of 0.257 mgprotein/ggel, and showed moderately lower activity in organically modified sol-gel than that in hydrophilic sol-gel. The effects of water/silane
ratio and precursor combinations on the activity of entrapped chlorophyllase were also studied by examining the pore morphology
of gel via nitrogen adsorption-desorption. Longer aging time leads to an entrapped chlorophyllase preparation with higher
activity. Chlorophyllase preparation demonstrated negligible activity after air-drying for 12 h while lyophilized chlorophyllase
preparation demonstrated 8, 4 and 4 times higher activity than air-dried, vacuum-dried and solvent-dried preparations. Chlorophyllase
demonstrated 30% higher activity in the improved sol-gel protocol than that from a non-optimized sol-gel protocol developed
in a previous study. 相似文献
45.
Sapelnikova S Dock E Solná R Skládal P Ruzgas T Emnéus J 《Analytical and bioanalytical chemistry》2003,376(7):1098-1103
Screen-printing technology for electrode fabrication enables construction of amperometric devices suitable for combination of several enzyme electrodes. To develop a biosensor array for characterisation of wastewaters, tyrosinase and horseradish peroxidase (HRP) or cholinesterase-modified electrodes were combined on the same array. The behaviour of the tyrosinase-modified electrode in the presence of hydrogen peroxide (required co-substrate for the HRP-modified electrode) and acetylthiocholine chloride (required co-substrate for cholinesterase) was studied. Performance of bi-enzyme biosensor arrays in the batch mode and in the flow-injection system are discussed. 相似文献
46.
This work reports on the synthesis of new unsymmetrically substituted phthalocyanines (M = Zn, Cu, Co, Ni) bearing three benzo-15-crown-5 units through oxy bridges and a nitro group. Phthalocyanines were prepared by a statistical condensation of 4-nitro phthalonitrile and 1-{[(benzo-15-crown-5)-4′-yl]oxy}phthalonitrile in the presence of anhydrous metal salts. All the target unsymmetrical phthalocyanines were separated by column chromatography and characterized elemental analyses, 1H NMR, IR, mass and UV–Vis spectral data. Electrochemical behaviors of Cu (II) phthalocyanine by cyclic voltammetry and differential pulse voltammetry techniques gave two common phthalocyanine ring reductions and one ring oxidation processes. Peak-to-peak separation of the processes II and III (388 mV) and the measure of gap (1.672 V) between the HOMO and LUMO for the complex, fits a phthalocyanine with electrochemically inactive metal center. 相似文献
47.
Natalizia Miceli Andreana Marino Ayşegül Köroğlu Francesco Cacciola Paola Dugo Luigi Mondello 《Natural product research》2020,34(11):1636-1641
AbstractThe purpose of this study was to conduct a comparative evaluation of some biological properties of methanol and water extracts of leaves of five Juniperus taxa growing in Turkey: J. communis L. var. communis (Jcc), J. communis L. var. saxatilis Pall. (Jcs), J. drupacea Labill. (Jd), J. oxycedrus L. subsp. oxycedrus (Joo), J. oxycedrus L. subsp. macrocarpa (Sibth. & Sm.) Ball. (Jom). The antioxidant properties were examined in vitro; both in the DPPH and in the reducing power tests, Joo methanol extract resulted the most active (IC50?=?0.09?±?0.01mg/mL and ASE/mL?=?2.56?±?0.06). In the TBA assay, Jcs methanol extract exhibited the highest activity (IC50?=?4.39?±?0.47?μg/mL). The extracts displayed bacteriostatic activity against Staphylococcus aureus, and Jd methanol extract resulted the most effective (MIC?=?19.53?μg/mL); no effect on the S. aureus biofilm formation was observed. The extracts resulted non-toxic in the Artemia salina lethality bioassay. Finally, the phenolic profile of the methanol extracts was characterized by HPLC-PDA/ESI-MS. 相似文献
48.
Muharrem Diner Namk
zdemir Sinan Saydam
zer Bekarolu Orhan Büyükgüngr 《Acta Crystallographica. Section C, Structural Chemistry》2006,62(2):o89-o91
The molecule of the title compound, C18H24N2O2, resides on a crystallographic inversion centre. The molecule adopts a transoid conformation with respect to the central C—C single bond and is in the meso form. A polarimetric study of the compound did not show any optical activity, indicating that the compound is a racemic mixture entirely consistent with the centrosymmetric space group. In the molecule, there is one intramolecular N—H⋯O interaction, resulting in the formation of a five‐membered ring. In the crystal structure, intermolecular O—H⋯N and C—H⋯O interactions are also observed. These interactions form an R22(9) ring and one‐dimensional linear chains of edge‐fused rings running parallel to the [010] direction, which stabilize the crystal packing. 相似文献
49.
The mechanism of interaction of trypsin with the sulfathiazole was studied through using fluorescence quenching and UV-visible absorption spectra at pH 7.4. The Stern-Volmer quenching constants, binding constants, number of binding sites and the corresponding thermodynamic parameters ΔHo, ΔSo and ΔGo were calculated at different temperatures. The effect of common metal ions on the constants was also discussed. The results suggest that sulfathiazole can interact strongly trypsin and that there is the formation of trypsin-sulfathiazole complex and the interaction can be explained on the basis of hydrogen bonds and van der Waals forces. The binding distance (r) between the donor (trypsin) and acceptor (sulfathiazole) was 3.52 nm based on the Förster’s non-radiative energy transfer theory. The detection and quantification limits of sulfathiazole were calculated as 2.52 and 8.40 μM in the presence of trypsin, respectively. The relative standard deviation (RSD) was 4.086 % for determinations (n?=?7) of a sulfathiazole solution with the concentration of 7.54 μM. 相似文献
50.
M. H. Elnagdi M. A. Selim F. M. Abd El Latif S. Samia 《Phosphorus, sulfur, and silicon and the related elements》2013,188(5):1175-1182
5-Acetyl-2-cyanomethyl-4-methylthiazole, 2-aminothiazole, and 5-N-benzoylamino-1,3,4-thiadiazole-2-yl-acetonitrile react with acetone, and malononitrile derivatives in the presence of sulfur to yield the corresponding thiophene derivatives. Also, 4-furylmethylene-2-phenyl-2-oxazolin-5-ones react with thiophenol, and/or thionaphthol to give the thiolester derivatives in one-pot synthesis. The structures of the products were based on IR, 1 H NMR, and elemental analysis. 相似文献