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81.
Dorfam Hajzamani Parvin Shokrollahi Najmeh Najmoddin Fatemeh Shokrolahi 《先进技术聚合物》2020,31(9):1896-1910
A three‐layered fibrous scaffold composed of fibers of different diameters in each layer was fabricated in correspondence with the structure of the blood vessels. Effect of solution and electrospinning parameters on morphology and diameters of the fibers were investigated by scanning electron microscopy (SEM), for each layer. The SEM images showed that 18% poly (lactic‐co‐glycolic acid) (PLGA)‐gelatin‐chitosan in 1,1,1,3,3,3‐hexafluoro‐2‐propanol (HFIP)/acid acetic solution resulted in bead‐free fibers for the outer layer. For the middle layer, 18% PLGA‐gelatin in HFIP at 13 kV with 13 cm needle to collector distance was chosen as the optimum condition. SEM imaging demonstrated that by increasing graphene content from 0.5 to 2 wt% in the inner layer (as an electrically conductive/platelet anti‐adhesion material), the fiber diameter decreased from 324.01 ± 58.90 to 288.59 ± 70.77 nm. The effect of gelatin crosslinking on the microstructure of the fibers was also examined. Shrinkage ratio decreased from 57 to below 21% upon crosslinking of the three‐layered scaffold in exposure to vapor of 50% glutaraldehyde solution for 2 hours. Mechanical test showed that tensile strength of the crosslinked three‐layer scaffold in the longitudinal direction was 2.90 MPa which is comparable to that of the vein and artery. The MTT [3‐(4,5‐Dimethylthiazol‐2‐yl)‐2,5‐diphenyltetrazolium bromide] assay displayed cell viability of above 96% for the PLGA‐gelatin containing 2 wt% graphene. SEM analysis revealed that the addition of graphene to PLGA‐gelatin (up to 2%) causes a remarkable improvement in cell adhesion. 相似文献
82.
Three new alkaloids, daphcalycinosidines A (1) and B (2) and daphcalycic acid (3) have been isolated from the seeds of Daphniphyllum calycinum. The structures and relative stereochemistries were determined on the basis of spectral studies including 2D NMR, mass spectrometry and chemical transformations. Structures 1 and 2 are characterized by an iridoid glucoside moiety linked to new Daphniphyllum alkaloid moieties. 相似文献
83.
Kumar Parvin 《中国化学》2010,28(2):250-254
Synthesis of bis‐1,3‐{6′‐arylimidazo[2,1‐b][1,3,4]thiadiazol‐2‐yl}‐1,2,2‐trimethylcyclopentane ( 3 ), bis‐1,3‐{thiadiazolo[2′,3′:2,1]imidazo[4,5‐b]quinoxalinyl}‐1,2,2‐trimethylcyclopentane ( 5 ) has been achieved by the reaction of bis‐(5′‐amino‐1′,3′,4′‐thiadiazolyl)‐1,2,2‐trimethylcyclopentane with α‐haloketones, 2,3‐dichloroquinoxaline respectively. Bromination of compound 3 furnished bis‐1,3‐{5′‐bromo‐6′‐arylimidazo[2,1‐b][1,3,4]thiadiazol‐2‐yl}‐1,2,2‐trimethylcyclopentane ( 4 ). The structural assignment of these compounds was supported by IR, 1H NMR and elemental analysis data. The antimicrobial, anti‐inflammatory and antifungal activities of some of the compounds have also been evaluated. 相似文献
84.
Parvin Sarabadani Mahdi Sadeghi Mohamadreza Ghasemi Zargham Asadollahi Narges Afshari 《Journal of Cluster Science》2011,22(2):131-140
High purity tin oxide nanopowders have been synthesized by using a solid-state chemical reaction technique with annealing
at elevated temperature. The effects of two parameters, specifically by controlling the annealing temperature and kind of
alkaline chlorides as precursors, the effect on particle size, morphology and IR spectra of synthesized tin oxide nanopowder
were investigated. From the X-ray pattern, the crystal structure of the synthesized powders was confirmed as a tetragonal
structure. Based on the recorded FTIR spectrum of SnO2, the IR bands due to SnO2 vibrations and its lattice modes were observed at 625 and 690 cm−1, respectively. In addition, an important characterization peak has been identified at 1,450 cm−1 due to Sn–O–Sn bridges observed only when LiCl was used as precursor. The formation of Sn–O–Sn bridges was confirmed by TGA–DTA
analysis. According to the SEM images, it is obvious to notice that the kind of alkaline chlorides as precursors play a dominant
role in controlling the morphology of tin oxide nanopowders. 相似文献
85.
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87.
Amir Hossein Noroozi Mahdi Sadeghi Ali Abbaspour Tehrani Parvin Sarabadani Saeed Rajabaifar Mohammad Mirzaee 《Journal of Cluster Science》2013,24(3):757-770
Several important synthetic parameters such as precursor concentration, reaction time are found to determine the growth of ZnO nanostructures. These reaction parameters can be tuned to produce a variety size of nanostructures. In this work we show the importance of these parameters on the size of synthesized zinc oxide nano-powders. ZnO nanoparticles are synthesized by the solid-state reaction using ZnSO4·7H2O and NaOH as the reagents. In this method Zn(OH)2 is the intermediate product of the reaction, we show that by adjusting the molar ratio of the reagents and grinding time, we can be removed this unwanted component in the final product so for obtaining pure ZnO nanostructures the calcinations process is not necessary, also we can tune the size of ZnO nanoparticles. XRD spectra of the nanoparticles demonstrate typical diffraction peaks of a well-crystalline Wurtzite ZnO structure transmission electron microscopic observations show that these nanoparticles are of hexagonal phase ZnO mostly in round shapes and he composition analysis by EDX indicate that final product is pure ZnO. In the optimum conditions by XRD analysis we see that the mean grain size of synthesized zinc oxide nano-particles is about 44 nm. 相似文献
88.
An expeditious and effective method for synthesis of isoxazoline from aldoximes and activated alkenes using cetyltrimethylammonium cerium nitrate at room temperature is described. Reaction was completed within short time period in high yields at room temperature. 相似文献
89.
Hoda El-Ghamry Rehab El-Sharkawy Mohamed Gaber 《Journal of the Iranian Chemical Society》2014,11(2):379-389
Co(II), Ni(II) and Cu(II) chloro complexes of benzilic hydrazide (BH) have been synthesized. Also, reaction of the ligand (BH) with several copper(II) salts, including NO3 ?, AcO?, and SO4 ? afforded metal complexes of the general formula [CuLX(H2O) n ]·nH2O, where X is the anion and n = 0, 1 or 2. The newly synthesized complexes were characterized by elemental analysis, mass spectra, molar conductance, UV–vis, IR spectra, magnetic moment, and thermal analysis (TG/DTG). The physico-chemical studies support that the ligand acts as monobasic bidentate towards metal ion through the carbonyl and hydroxyl oxygen atoms. The spectral data revealed that the geometrical structure of the complexes is square planar for Cu (II) complexes and tetrahedral for Co(II) and Ni(II) complexes. Structural parameters of the ligand and its complexes have been calculated. The ligand and its metal complexes are screened for their antimicrobial activity. The catalytic activities of the metal chelates have been studied towards the oxidative decolorization of AB25, IC and AB92 dyes using H2O2. The catalytic activity is strongly dependent on the type of the metal ion and the anion of Cu(II) complexes. 相似文献
90.
Simultaneous Determination of Ascorbic Acid,Dopamine and Uric Acid,at a Graphene Paste Electrode Modified with Functionalized Graphene Sheets 下载免费PDF全文
Mohammad Hadi Parvin 《Electroanalysis》2015,27(6):1394-1402
The present study reports the simultaneous determination of ascorbic acid (AA), dopamine (DA) and uric acid (UA) in phosphate buffer solution (pH 7.0) using graphene paste electrode modified with functionalized graphene sheets (GPE‐MFGSs). The presence of FGS inhibited the adsorption of AA owing to the electrostatic repulsion, but was favorable for the affinity adsorption of DA and UA via the ion exchange and hydrogen bonding mechanisms, respectively. This led to the decrease in the oxidation potential of AA and the significantly enhanced oxidation peak currents of DA and UA at the GPE‐MFGSs. By cyclic voltammetry and differential pulse voltammetry, the oxidation potentials of AA, DA, and UA, at the GPE‐MFGSs in a ternary mixture were found to be well resolved so that their simultaneous determination could be achieved. Furthermore, the influence of some experimental variables such as graphene paste composition, working solution pH, scan rate and pulse amplitude was studied. In addition, by differential pulse voltammetry, the linear dependence of peak current on the concentration was obtained in the ranges of 0.05–9.0, 0.03–13, and 0.03–5.5 µM with the lowest detection limits of 0.02, 0.01, and 0.01 µM for AA, DAand UA, , respectively. 相似文献