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排序方式: 共有193条查询结果,搜索用时 15 毫秒
101.
Navid Dehnavi Kazem Parivar Vahabodin Goodarzi Ali Salimi Mohammad Reza Nourani 《先进技术聚合物》2019,30(9):2192-2206
Peripheral nerve injury can considerably affect the daily life of affected people through reduced function and permanent deformation of the nerve. One of the conventional treatments used for the management of the disease is the application of autograft, which is recognized as a golden standard method; however, the process of gaining access to autograft has posed a significant challenge to its use. Nerve guidance channels (conduits), which are made in different methods, can act as an alternative therapy for patients that have undergone nerve injury; but, achieving these conduits has always been a major dilemma to be applied for patients with nerve injury. In this study, a novel conduit based on polymer blend nanocomposites of polyglycolic acid (PGA), collagen, and nanobioglass (NBG) were prepared by electrospinning technique and then compared with PGA/collagen and PGA conduits that were made in previous studies. Additionally, their various properties were characterized by scanning electron microscopy (SEM), X‐ray diffraction (XRD), contact angle, dynamic mechanical thermal analysis (DMTA), tensile strength, Fourier‐transform infrared (FTIR), and the porosity and degradation. The results showed that the mechanical, chemical, biocompatibility, and biodegradability properties of PGA/collagen/NBG conduits were more favorable in comparison with other materials. According to 3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyltetrazolium bromide (MTT) assay and 4′,6‐diamidino‐2‐phenylindole (DAPI) staining technique, nanofibrous electrospun PGA/collagen/NBG conduits are more suitable for cell adhesion and proliferation in comparison with either PGA or PGA/collagen conduits and can have potential for nerve regeneration. 相似文献
102.
Soheilnia N Kleinke KM Dashjav E Cuthbert HL Greedan JE Kleinke H 《Inorganic chemistry》2004,43(20):6473-6478
A new modification of CuTi(2)S(4) was prepared from the elements at 425 degrees C. It crystallizes in the rhombohedral space group Rm, with lattice parameters of a = 7.0242(4) A, c = 34.834(4) A, and V = 1488.4(2) A(3) (Z = 12). Two topologically different interlayer regions exist between the close-packed S layers that alternate along the c axis: one comprises both Cu (in tetrahedral voids) and Ti atoms (in octahedral voids), and the second exclusively Ti atoms (again in octahedral voids). In contrast to the known modification, the spinel, Cu-Ti interactions of 2.88 A occur that have bonding character according to the electronic structure calculations. Both CuTi(2)S(4) modifications are metallic Pauli paramagnets due to Ti d contributions. The Pauli susceptibility of the Rm form is larger than that of the thiospinel in quantitative agreement with the LMTO-ASA band structure calculations. The irreversible transformation to the spinel takes place at temperatures above 450 degrees C. 相似文献
103.
Haji Shabani AM Dadfarnia S Nasirizadeh N 《Analytical and bioanalytical chemistry》2004,378(5):1388-1391
Trace amounts of inorganic mercury (Hg2+) and methylmercury cations (MeHg2+) were adsorbed quantitatively from acidic aqueous solution onto a column packed with immobilized dithizone on microcrystalline naphthalene. The trapped mercury was eluted with 10 ml of 7 mol L–1 hydrochloric acid solution. The Hg2+ was then directly reduced with tin (II) chloride, and volatilized mercury was determined by cold vapor atomic absorption spectrometry (CVAAS). Total mercury (Hgt) was determined after decomposition of MeHg+ into Hg2+. Hg2+ and MeHg+ cations were completely recovered from the water with a preconcentration factor of 200. The relative standard deviation obtained for eight replicate determinations at a concentration of 0.3 g L–1 was 1.8%. The procedure was applied to analysis of water samples, and the accuracy was assessed via recovery experiment. 相似文献
104.
Abouzar Roeintan Sayed Mojtba Moosavi Mohammad Navid Soltani Rad Somayeh Behrouz 《中国化学会会志》2015,62(12):1097-1104
The ‘click synthesis’ of some novel O‐substituted oximes, 5a – 5j , which contain heterocycle residues, as new analogs of ß‐adrenoceptor antagonists is described (Scheme 1). The synthesis of these compounds was achieved in four steps. The formation of (E)‐2‐(1H‐benzo[d]imidazol‐1‐yl)‐1‐phenylethanone oxime, followed by their reaction with 2‐(chloromethyl)oxirane, afforded mixture of oil compounds 3 and 4 , which by a subsequent tetra‐n‐butylammonium bromide (TBAB)‐catalyzed reaction with N H heterocycle compounds (Scheme 1), led to the target compounds 5a – 5j in good yields. 相似文献
105.
Rajagopal Karthikeyan Hasanzadeh Navid Parastesh Fatemeh Hamarash Ibrahim Ismael Jafari Sajad Hussain Iqtadar 《Nonlinear dynamics》2020,101(1):711-718
Nonlinear Dynamics - The outbreak of the novel coronavirus (COVID-19), which was firstly reported in China, has affected many countries worldwide. To understand and predict the transmission... 相似文献
106.
The main aim of this study was to predict current and future flood susceptibility under three climate change scenarios of RCP2.6 (i.e., optimistic), RCP4.5 (i.e., business as usual), and RCP8.5 (i.e., pessimistic) employing four machine learning models, including Gradient Boosting Machine (GBM), Random Forest (RF), Multilayer Perceptron Neural Network (MLP-NN), and Naïve Bayes (NB). The study was conducted for two watersheds in Canada, namely Lower Nicola River, BC and Loup, QC. Three statistical metrics were used to validate the models: Receiver Operating Characteristic Curve, Figure of Merit, and F1-score. Findings indicated that the RF model had the highest accuracy in providing the flood susceptibility maps (FSMs). Moreover, the provided FSMs indicated that flooding is more likely to occur in the Lower Nicola River watershed than the Loup watershed. Following the RCP4.5 scenario, the area percentages of the flood susceptibility classes in the Loup watershed in 2050 and 2080 have changed by the following percentages from the year 2020 and 2050, respectively: Very Low = −1.68%, Low = −5.82%, Moderate = +6.19%, High = +0.71%, and Very High = +0.6% and Very Low = −1.61%, Low = +2.98%, Moderate = −3.49%, High = +1.29%, and Very High = +0.83%. Likewise, in the Lower Nicola River watershed, the changes between the years 2020 and 2050 and between the years 2050 and 2080 were: Very Low = −0.38%, Low = −0.81%, Moderate = −0.95%, High = +1.72%, and Very High = +0.42% and Very Low = −1.31%, Low = −1.35%, Moderate = −1.81%, High = +2.37%, and Very High = +2.1%, respectively. The impact of climate changes on future flood-prone places revealed that the regions designated as highly and very highly susceptible to flooding, grow in the forecasts for both watersheds. The main contribution of this study lies in the novel insights it provides concerning the flood susceptibility of watersheds in British Columbia and Quebec over time and under various climate change scenarios. 相似文献
107.
Xue-Qing Gong Navid Khorshidi Vedran Vonk Helmut Dosch Annabella Selloni Olga Dulub 《Surface science》2009,603(1):138-144
An extensive search for possible structural models of the (2 × 1)-reconstructed rutile TiO2(0 1 1) surface was carried out by means of density functional theory (DFT) calculations. A number of models were identified that have much lower surface energies than the previously-proposed ‘titanyl’ and ‘microfaceting’ models. These new structures were tested with surface X-ray diffraction (SXRD) and voltage-dependent STM measurements. The model that is (by far) energetically most stable shows also the best agreement with SXRD data. Calculated STM images agree with the experimental ones for appropriate tunneling conditions. In contrast to previously-proposed models, this structure is not of missing-row type; because of its similarity to the fully optimized brookite TiO2(0 0 1) surface, we call it the ‘brookite (0 0 1)-like’ model. The new surface structure exhibits two different types of undercoordinated oxygen and titanium atoms, and is, in its stoichiometric form, predicted to be rather inert towards the adsorption of probe molecules. 相似文献
108.
Mohammad Hossein Karami Mohammad Reza Kalaee Saeideh Mazinani Mohamadreza Shakiba Saied Shafiei Navid Majid Abdouss Alireza Beig Mohammadi Weisong Zhao Mojtaba Koosha Ziyue Song Tianduo Li 《Molecules (Basel, Switzerland)》2022,27(9)
In this study, the curing kinetics of epoxy nanocomposites containing ultra-fine full-vulcanized acrylonitrile butadiene rubber nanoparticles (UFNBRP) at different concentrations of 0, 0.5, 1 and 1.5 wt.% was investigated. In addition, the effect of curing temperatures was studied based on the rheological method under isothermal conditions. The epoxy resin/UFNBRP nanocomposites were characterized via Fourier transform infrared spectroscopy (FTIR). FTIR analysis exhibited the successful preparation of epoxy resin/UFNBRP, due to the existence of the UFNBRP characteristic peaks in the final product spectrum. The morphological structure of the epoxy resin/UFNBRP nanocomposites was investigated by both field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) studies. The FESEM and TEM studies showed UFNBRP had a spherical structure and was well dispersed in epoxy resin. The chemorheological analysis showed that due to the interactions between UFNBRP and epoxy resin, by increasing UFNBRP concentration at a constant temperature (65, 70 and 75 °C), the curing rate decreases at the gel point. Furthermore, both the curing kinetics modeling and chemorheological analysis demonstrated that the incorporation of 0.5% UFNBRP in epoxy resin matrix reduces the activation energy. The curing kinetic of epoxy resin/UFNBRP nanocomposite was best fitted with the Sestak–Berggren autocatalytic model. 相似文献
109.
A study of the mechanism of the catalytic transformation of mixed ethyl acetate (EA) + methyl acetate (MA) (50:50 v/v) to hydrocarbons over HZSM‐5 (Si/Al ratio of 9) catalyst was conducted. The reaction was carried out in a continuous fixed‐bed reactor under atmospheric pressure and in the temperature range 250–390°C and with weight hourly space velocity of 3.2 and 4.6 h?1. The distribution of products including monoaromatics, fused ring aromatics and oxygenates was determined using GC‐MS. The product distribution was controlled by temperature. The oxygenate components (kinetically controlled products) were transformed into aromatics (thermodynamically controlled products) with an increase in temperature. The effluents were benzene‐free or with low content of benzene and toluene. Two intermediates were proposed for this conversion to hydrocarbons over HZSM‐5: cyclobutane‐1,3‐dione and/or acetic acid (AA) as ketene source. Furthermore, AA and mesityl oxide (MO) were selected as potential intermediates in the transformation of mixed EA + MA into hydrocarbons over HZSM‐5. It is suggested that ketene dimerization, the phenolic pool and the condensation reaction between ketene and MO are the probable mechanism routes for AA conversion. Aldol condensation, Michael addition, cracking, isomerization and ketene formation are the presumable pathways for MO conversion over HZSM‐5. 相似文献
110.
Irannejad-Gheshlaghchaei Navid Zare Abdolkarim Sajadikhah Seyed Sajad Banaei Alireza 《Research on Chemical Intermediates》2018,44(10):6253-6266
Research on Chemical Intermediates - A novel dicationic ionic liquid, N,N,N′,N′-tetramethyl-N,N′-bis(sulfo)ethane-1,2-diaminium mesylate [TMBSED][OMs]2), has been produced, and... 相似文献