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61.
Sevda Dehghani Ahad Hanifpour Mehdi Nekoomanesh-Haghighi Samahe Sadjadi Seyed Amin Mirmohammadi Ali Farhadi Naeimeh Bahri-Laleh 《应用聚合物科学杂志》2020,137(22):49018
The main aim of this research is to decrease the amount of AlCl3 content that is very corrosive and hazardous in the catalytic system, required for the α-olefin oligomerization without substantial change of final oil features. This was successfully achieved by supporting AlCl3 on different carriers. More precisely, a series of supported bimetallic catalysts was synthesized by immobilization of AlCl3 and TiCl4 onto Al2O3, SiO2, and mixed supports, that is, Al2O3/FeCl3 and SiO2/FeCl3. It was found that silica and alumina-based catalysts had higher catalytic activities compared to support free AlCl3; however, this enhancement for silica-based supports was more significant. According to gel permeation chromatography (GPC) results, the use of single supports, that is, Al2O3 and SiO2, increased oligomer's molecular weight, while the application of mixed supports resulted in the decrease of molecular weight of the oligomers. Viscosity characteristics of the synthesized oligomers have also been studied at two different temperatures of 40 and 100°C (KV40 and KV100). The viscosity index (VI) values, derived from KV40 and KV100, of the prepared oligomers were in the range of 126–145. The molecular weight and termination mechanisms of the oligomers were studied by 1H-NMR spectroscopy. The obtained results disclosed that the employed reaction conditions led to the production of oligomer chains with various structures including vinylidene (Vd), and di and three-substituted vinylene (2Vn, 3Vn) structures. 相似文献
62.
Mohammad Dana Mohammad Amin Sobati Shahrokh Shahhosseini Aminreza Ansari 《中国化学工程学报》2020,28(5):1384-1396
A continuous-flow ultrasound-assisted oxidative desulfurization(UAOD) of partially hydro-treated diesel has been investigated using hydrogen peroxide-formic acid as simple and easy to apply oxidation system. The effects of different operating parameters of oxidation stage including residence time(2–24 min), formic acid to sulfur molar ratio(10–150), and oxidant to sulfur molar ratio(5–35) on the sulfur removal have been studied using response surface methodology(RSM) based on Box–Behnken design. Considering the operating costs of the continuous-flow oxidation stage including chemical and electrical energy consumption, the appropriate values of operating parameters were selected as follows: residence time of 16 min, the formic acid to sulfur molar ratio of 54.47, and the oxidant to sulfur molar ratio of 8.24. In these conditions, the sulfur removal and the volume ratio of the hydrocarbon phase to the aqueous phase were 86.90% and 4.34, respectively. By drastic reduction in the chemical consumption in the oxidation stage, the volume ratio of the hydrocarbon phase to the aqueous phase was increased up to 10. Therefore, the formic acid to sulfur molar ratio and the oxidant to sulfur molar ratio were obtained 23.64 and 3.58, respectively, which lead to sulfur removal of 84.38% with considerable improvements on the operating cost of oxidation stage in comparison with the previous works. 相似文献
63.
Photo-oxidative degradation reactions are mainly responsible for reduced lifetime in polymers. These reactions are responsible for the decay in useful physical and chemical properties of polymers. In addition to high ultraviolet radiation doses, hostile environments have increased temperature, high humidity, and air-borne sand. In this work white pigmented polyvinyl chloride (PVC) pipe sections were exposed to natural weather at seven different locations. Characterization studies were made on exposed samples using Fourier transform infrared (FTIR) spectroscopic, gel permeation chromatographic (GPC), and scanning electron microscopic (SEM) studies. Performance characteristics were determined by testing changes in the mechanical properties. Functional groups introduced during the processing of PVC and irregularities in the polymer chain can be held responsible for the initiation and propagation of photo-oxidative degradation reactions catalyzed by high surface temperature and increased humidity. 相似文献
64.
Bijan Bina Farzaneh Mohammadi Mohammad Mehdi Amin Hamid Reza Pourzamani Zeynab Yavari 《中国化学工程学报》2018,26(1):183-190
Alkylphenols(APs), considered as xenoestrogenic compounds, mainly exist as 4-nonylphenol(4-NP) and 4-tertoctylphenol(4-t-OP) in environments. The high stability and accumulation of APs in aquatic systems have caused endocrine disruption. In this study we measured APs in the wastewater influent and effluent samples, from the urban, rural, livestock, commercial and hospital wastewater treatment plants(WWTPs) in Iran. Dispersive liquid–liquid microextraction(DLLME) combined with gas chromatography–mass spectrometry(GC–MS) was used for the extraction and determination of 4-NP and 4-t-OP. In these treatment plants, various processes such as activated sludge, aerated lagoon, moving bed biofilm reactor and activated sludge along with wetland were applied. The highest concentration of 4-NP and 4-t-OP was observed in commercial and livestock sewages. The activated sludge along with wetland and then the MBBR process showed the highest removal rates of pollutants. The rates of biodegradability and accumulation in sludge were determined and also the specific adsorption coefficient Kdand the organic carbon–water partition coefficient kOCof the sludge for APs were calculated. 相似文献
65.
66.
Synthesis,characterization, rheological and thermal behavior of metallocene ethylene − norbornene copolymers with low norbornene content using pentafluorophenol modified methylaluminoxane 下载免费PDF全文
Ethylene ? norbornene copolymers were synthesized using rac‐ethylene bis(indenyl) zirconium dichloride/pentafluorophenol modified methylaluminoxane. First, the effect of using a modifier in combination with a low ratio of Al/Zr on the catalyst activity and co‐monomer incorporation was studied. The results of copolymerization reveal a 20% co‐monomer incorporation improvement and a rise of activity by 2‐fold in the presence of the modifier. Rheological measurements show a higher molecular weight in copolymers synthesized using modified methylaluminoxane. The alternative and dyad block microstructures of copolymers become possible in the case of a norbornene content of more than 14 mol%. Second, the effect of co‐monomer content on the rheological and thermal behavior of the synthesized copolymers was investigated. The results of the rheological study indicate a lower molecular weight in samples containing a higher norbornene content. Dynamic mechanical thermal analysis confirms the influence of different microstructures on the glass transition temperature. The crystal structure of copolymers having a higher molecular weight is emphasized using wide angle X‐ray scattering and DSC even with a greater incorporation of norbornene. © 2015 Society of Chemical Industry 相似文献
67.
Hong Tsao Olga Rechkoblit Shantu Amin Nicholas E. Geacintov 《Polycyclic Aromatic Compounds》2013,33(1-4):1-10
Adducts derived from the binding of the (+)-7R,8S,9S,10R and (?)-7S,8R,9R,10S enantiomers of r7,t8-dihydrodiol-t9,10-epoxy-7,8,9,10-tetrahydrobenzo[a]pyrene (anti-BPDE) to 2′-deoxyguanosine residues in DNA are known to induce mutations due to error-prone DNA replication. Because the conformational properties of these lesions may be important in these phenomena, we have examined the effects of the stereoisomeric (+)- and (?)-trans-anti-[BP]-N 2-dG lesions positioned site-specifically at or near primer/template oligonucleotide junctions on DNA bending using high resolution gel electrophoresis. Remarkable differences in electrophoretic mobilities μ are observed in the two adducts derived from the tumorigenic (+)-anti-BPDE, and the non-tumorigenic (?)-anti-BPDE enantiomer. With the (+)-trans lesion positioned on the template strand adjacent to the 3′-end of the primer strand, a remarkable decrease in μ is observed. This suggests the existence of a bend at the single strand-double strand junction. Only modest decreases in μ are observed in the case of the (?)-trans lesion, or when the 3′-end is opposite to, or more distant from the lesion site. These observations are discussed in terms of the known NMR solution structures of these lesions in the same sequence context, and the properties of primer/template DNA in polymerases. 相似文献
68.
Arun K. Sharma Jacek Krzeminski Dhimant Desai Shantu Amin 《Polycyclic Aromatic Compounds》2013,33(3):297-305
Syntheses of naphtho[8,1,2- ghi ]chrysene (naphtho[1,2- e ]pyrene, N[ e ]P) 1 , dibenzo[ c,mno ]chrysene (naphtho[1,2- a ]pyrene, N[ a ]P) 2 and their dihydrodiol metabolites are described. The hydrocarbons N[ e ]P 1 and N[ a ]P 2 and their fjord region dihydrodiols 12 and 19 were synthesized using a Suzuki cross-coupling reaction followed by the appropriate manipulation of the functional groups. The K-region cis dihydrodiols of N[ e ]P-4,5-diol 20 , N[ a ]P-4,5-diol 23 , N[ a ]P-7,8-diol 24 were obtained by OsO 4 oxidation. The cis diols thus obtained were first converted to the corresponding quinones with pyridinium chlorochromate and, finally, to the desired trans dihydrodiols 22 , 27 , and 28 by NaBH 4 reduction. The mixture of trans N[ a ]P-4,5- and 7,8-dihydrodiols was separated by high-performance liquid chromatography. 相似文献
69.
The morphological transforming activities in mouse embryo C3H10T1/2CL8 (C3H10T1/2) cells were examined for six PAHs: benzo[c]chrysene (B[c]C); benzo[g]chrysene (B[g]C); benzo[c]phenanthrene (B[c]P); dibenzo[a, l]pyrene (DB[a, l]P); dibenzo[a,e]pyrene (DB[a,e]P) and benzo[a]pyrene (B[a]P). C3H10T1/2 cells treated with B[c]P or B[g]C at concentrations of 0–3 μg/ml did not produce any transformed Type II or III foci after 24 hr of exposure. Concurrent cytotoxicity was observed. Under the same conditions, B[a]P and B[c]C were active, with B[c]C approximately one-half the activity of B[a]P. However, after a 48-hr treatment, B[c]P and B[g]C gave significant activity measured as both foci/dish or the number of dishes exhibiting foci. After a 24-hr treatment, comparison of B[a]P with two dibenzopyrenes, DB[a, l]P and DB[a,e]P, gave activities in the order: DB[a, l]P > B[a]P > DB[a,e]P. After 48 hr of treatment, both B[a]P and DB[a,e]P had similar activities. 相似文献
70.
Novel inimer was synthesized from p-amino phenol via successive preparative methods by using both bromoisobutyrylbromide and acryloyl chloride. The new inimer was well characterized via Infrared Spectra (IR) and 1 H nuclear magnetic resonance (NMR). New hyperbranched polyamide (H1) was prepared via Atom Transfer Radical Polymerization (ATRP). Several reaction conditions (ligands, solvents, temperatures, etc.) were studied. However, the N,N,N′,N″,-pentamethyldiethylenetriamine (PMDETA)/CuBr catalytic system showed good results in toluene at 100°C. Three arm star methylmethacrylate (MMA) homopolymers reacted with (H1) in different percentages to form copolymers with low polydispersity values, especially at 1:115 for poly MMA:H1. The formed polymers were characterized via Gel Permeation Chromatography (GPC), 1 HNMR, thermal analyses, and Transmission Electron Microscopy (TEM). 相似文献