全文获取类型
| 收费全文 | 857篇 |
| 免费 | 15篇 |
| 国内免费 | 8篇 |
专业分类
| 电工技术 | 19篇 |
| 综合类 | 7篇 |
| 化学工业 | 222篇 |
| 金属工艺 | 22篇 |
| 机械仪表 | 24篇 |
| 建筑科学 | 40篇 |
| 矿业工程 | 1篇 |
| 能源动力 | 61篇 |
| 轻工业 | 60篇 |
| 水利工程 | 6篇 |
| 石油天然气 | 5篇 |
| 无线电 | 68篇 |
| 一般工业技术 | 160篇 |
| 冶金工业 | 24篇 |
| 原子能技术 | 10篇 |
| 自动化技术 | 151篇 |
出版年
| 2025年 | 1篇 |
| 2024年 | 21篇 |
| 2023年 | 19篇 |
| 2022年 | 35篇 |
| 2021年 | 64篇 |
| 2020年 | 73篇 |
| 2019年 | 58篇 |
| 2018年 | 86篇 |
| 2017年 | 47篇 |
| 2016年 | 45篇 |
| 2015年 | 29篇 |
| 2014年 | 56篇 |
| 2013年 | 97篇 |
| 2012年 | 60篇 |
| 2011年 | 61篇 |
| 2010年 | 41篇 |
| 2009年 | 32篇 |
| 2008年 | 9篇 |
| 2007年 | 13篇 |
| 2006年 | 11篇 |
| 2005年 | 4篇 |
| 2004年 | 4篇 |
| 2003年 | 4篇 |
| 2002年 | 1篇 |
| 1999年 | 2篇 |
| 1994年 | 2篇 |
| 1992年 | 2篇 |
| 1991年 | 1篇 |
| 1987年 | 1篇 |
| 1979年 | 1篇 |
排序方式： 共有880条查询结果，搜索用时 15 毫秒
91.
92.
Ehsan Naderi Kalali Anabel Montes Xin Wang Lu Zhang Marjan E. Shabestari Zhi Li De‐Yi Wang 《火与材料》2018,42(2):213-220
Phytic acid–modified layered double hydroxide (Ph‐LDH) was synthesized via coprecipitation method and subsequently was used in polypropylene (PP) by combining with an ammonium polyphosphate (APP) via melt compounding method. The synergistic effect between APP and Ph‐LDH on the thermal stability, flammability, and mechanical properties of the resultant PP composites was investigated by thermogravimetric analysis, limiting oxygen index, vertical burning test (UL‐94), cone calorimeter tests, tensile test, and impact test. Morphologies of the chars obtained from the samples after the cone calorimeter tests were studied by scanning electron microscopy. The combination of APP and Ph‐LDH slightly influenced the impact and tensile properties of PP. Also, the synergistic effect between APP and Ph‐LDH occurred in the cone calorimeter test. Moreover, the combination of APP and Ph‐LDH produced better quality char that effectively suppressed the spread of the flame and volatile and finally extinguished the fire. 相似文献
93.
In this work, polypropylene/thermoplastic starch (PP/TPS) with and without halloysite nanotubes (HNTs) was prepared via melt mixing in order to obtain environmentally friendly plastics. PP‐grafted maleic anhydride (PP‐g‐MA) was used to improve the compatibility among the highly incompatible polymers. The mechanical characterization showed a reduction in the tensile properties of the polymer when TPS increased; however, HNT successfully compensated for some of the observed losses. The results from the thermogravimetric analysis (TGA) indicated that HNT is an efficient reinforcement for the thermal stability improvement. TPS caused an increase in the storage modulus (G′) and the complex viscosity (η*) which marks a change in the viscoelastic properties of the system. The scanning electron microscope (SEM) images showed the effective plasticization of starch and better dispersion of TPS in the presence of HNT. Some samples were also buried in the soil to measure their sustainability after their lifetime lapse. The results indicated that TPS improves the biodegradability of the PP/TPS system. PP considerably lowered the moisture uptake of TPS; nevertheless, HNT caused a slight increase in the moisture absorption. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45740. 相似文献
94.
In this study, we synthesized novel films based on bacterial cellulose (BC), BC modified by polypyrrole (PPy), and a PPy–zinc oxide nanocomposite (BC–PPy–ZnO). The soft polymerization method at room temperature was used to obtain the BC–PPy and BC–PPy–ZnO films. The Combined D‐Optimal design was used to study the effects of the pyrrole monomer concentration, ZnO concentration, and polymerization time on the morphological, physical, color, and electrical conductivity properties of the films. Fourier transform infrared results reflected that some new interactions occurred between BC and PPy and PPy–ZnO. The X‐ray diffraction analysis showed that the crystalline behavior of the BC fiber was hindered because of the complete coating with the amorphous PPy particles. Scanning electron microscopy results show that the ZnO, PPy, and PPy–ZnO nanoparticles were placed between the BC fibers. PPy decreased the water vapor permittivity and total soluble matter percentage. Electrical conductivity studies of the synthesized BC–PPy–ZnO film showed that the film's electrical resistance was changed in different oxidation–reduction or volatile compounds media, so the results suggest that the BC–PPy–ZnO films could be used in antioxidative food active packaging and smart packaging. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46617. 相似文献
95.
In the present paper, two gas‐liquid stirred tanks, one agitated by a radial impeller and another by an axial impeller, are modelled using the open‐source computational fluid dynamic (CFD) package OpenFOAM (open source field operation and manipulation). The combined effect of the bubble break‐up and coalescence in the tank is considered by a population balance model (PBM) called extended quadrature method of moments (EQMOM). The three‐dimensional simulation is made using a multiple reference frame (MRF), a well‐established method for the modelling of mixers. Dispersed gas and bubble dynamics in the turbulent flow are modelled using the Eulerian‐Eulerian approach (E‐E) with mixture k‐epsilon turbulent model and the modified Tomiyama drag coefficient for the momentum exchange. The model is developed to predict the spatial distribution of gas phase fraction, Sauter mean bubble diameter (), number density function (NDF), dissolved oxygen (DO) evolution, and flow structure. The numerical results are compared with experimental data and a fair agreement is achieved. The results of the axial impeller are discussed based on four impeller rotational speeds with different volumetric mass transfer coefficients. 相似文献
96.
This work aims to improve the rheological properties and stability of multiwalled carbon nanotubes (MWCNTs)/acrylamide (AA) base skeleton polymer blends at harsh environment of high salinity-high temperature (HS-HT) or various pH. Different co/terpolymers have been accomplished to modify the structure of AA polymer by free-radical copolymerization of AA-based monomers. Anionic, cationic, and hydrophobic functional groups were used for the synthesis of polyelectrolyte, polyampholytic, and partially hydrophobic AA polymer types. The conversion, molecular weight, and poly dispersity of co/terpolymers have been evaluated by nuclear magnetic resonance (1H-NMR), gel permeation chromatography, and differential scanning calorimetry analysis. The effects of sonication power, concentration of polymer, and concentration of MWCNTs were also investigated on rheological behavior of co/terpolymers. The results show that negative polyelectrolyte and polyampholytic polymers are the best candidates for the improvement of MWCNTs/polymer stability and viscosity at HS-HT and alkali environment, respectively. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47205. 相似文献
97.
A combination of reduced graphene oxide (rGO) nanosheets grafted with regioregular poly(3‐hexylthiophene) (P3HT) (rGO‐g‐P3HT) and P3HT‐b‐polystyrene (PS) block copolymers was utilized to modify the morphology of P3HT:[6,6]‐phenyl‐C71‐butyric acid methyl ester (PC71BM) active layers in photovoltaic devices. Efficiencies greater than 6% were acquired after a mild thermal annealing. To this end, the assembling of P3HT homopolymers and P3HT‐b‐PS block copolymers onto rGO‐g‐P3HT nanosheets was investigated, showing that the copolymers were assembled from the P3HT side onto the rGO‐g‐P3HT nanosheets. Assembling of P3HT‐b‐PS block copolymers onto the rGO‐g‐P3HT nanosheets developed the net hole and electron highways for charge transport, thereby in addition to photoluminescence quenching the charge mobility (μh and μe) values increased considerably. The best charge mobilities were acquired for the P3HT50000:PC71BM:rGO‐g‐P3HT50000:P3HT7000‐b‐PS1000 system (μh = 1.9 × 10?5 cm2 V–1 s–1 and μe = 0.8 × 10?4 cm2 V–1 s–1). Thermal annealing conducted at 120 °C also further increased the hole and electron mobilities to 9.8 × 10?4 and 2.7 × 10?3 cm2 V–1 s–1, respectively. The thermal annealing acted as a driving force for better assembly of the P3HT‐b‐PS copolymers onto the rGO‐g‐P3HT nanosheets. This phenomenon improved the short circuit current density, fill factor, open circuit voltage and power conversion efficiency parameters from 11.13 mA cm?2, 0.63 V, 62% and 4.35% to 12.98 mA cm?2, 0.69 V, 68% and 6.09%, respectively. © 2019 Society of Chemical Industry 相似文献
98.
Masoud Homayouni&#x;Tabrizi Mozhgan Soltani Ehsan Karimi Farideh Namvar Vahid Pouresmaeil Ali Es&#x;haghi 《IET nanobiotechnology / IET》2019,13(6):617
One of the most important challenges in treating cancer is the invasion and the angiogenesis of cancer cells. The synthesis of green nanoparticles (NPs) and their use in therapeutic fields is one of the most effective methods with minimal side effects in cancer treatment. In this study, cytotoxic and anti‐angiogenic effects of silver NPs (AgNPs) coated with palm pollen extract [Ag–PP(NPs)] were evaluated. For this purpose, the cells were treated with NPs and then were subjected to trypan blue testing (48 h). Then, the cancer invasion was evaluated by the scratch procedure and the expressions of the vascular endothelial growth factor (VEGF) and its receptor (VEGF‐R) genes were estimated using real‐time PCR assay. Also, the angiogenesis effect of the NPs was investigated with chick chorioallantoic membrane (CAM) assay. The Ag–PP(NPs) induced cytotoxicity on MCF7 cells. The findings also showed that Ag–PP(NPs) inhibit invasive cancer cells and reduce the expression of VEGF and VEGF‐R and significantly reduced the number and vessels lengths and the lengths and weights of the embryos in CAM assay. Ag–PP(NPs) with the induction of cytotoxic effects, metastatic inhibition and anti‐angiogenesis properties should be considered as an appropriate option for treatment of cancerInspec keywords: nanomedicine, genetics, cellular biophysics, toxicology, patient treatment, silver, cancer, biochemistry, biomedical materials, nanoparticles, nanofabrication, membranesOther keywords: minimal side effects, cancer treatment, silver NPs, cancer invasion, vascular endothelial growth factor, receptor genes, VEGF‐R, real‐time polymerase chain reaction assay, angiogenesis effect, chick chorioallantoic membrane assay, MCF7 cells, invasive cancer cells, cytotoxic effects, putative mechanism, anticancer properties, antiangiogenic effects, antiangiogenesis properties, Ag–PP‐induced cytotoxicity, metastatic inhibition, palm pollen extraction, trypan blue testing, time 48.0 hour, Ag 相似文献
99.
Omid Amiri Amir Ehsan Rezaee Hakimeh Teymourinia Masoud Salavati‐Niasari L. Jay Guo Ardashir Baktash 《Advanced Materials Interfaces》2019,6(9)
Current efficiency of perovskite solar cells has reached 23.7%, which is comparable with silicon solar cells. However commercial development is seriously hindered by the instability of the perovskite, especially under moisture conditions. Therefore it is crucial to gain clear understanding of the mechanism of degradation of organic–inorganic perovskite in order to achieve stable perovskite devices. In this paper, the formation and the degradation of perovskite film on different charge transport layers such as a compact TiO2 layer, compact ZnO layer, and ZnO foil, Si nanowires, and porous Si are studied. In addition, density functional theory studies are carried out to better understand the interaction between the perovskite film and substrates. Experimental and theoretical results are combined to draw more reliable conclusion regarding the degradation mechanism. Most notably, the investigations show that the interaction between the iodine (I) atom in the perovskite layer and substrate determine the stability of perovskite cells. As a result, Si has minimum interaction with I atoms and shows maximum stability, while perovskite film degrades on TiO2 film almost immediately. 相似文献
100.
Reza Aliasgarian Malek Naderi Seyyed Ehsan Mirsalehi Saeed Safi 《Journal of Materials Engineering and Performance》2018,27(8):3900-3910
SiC coatings were generated on graphite using slurry sintering (SS) and pack cementation (PC). The samples’ ablation features were assessed by an oxyacetylene torch. The rates of mass ablation of the PC–SiC and SS–SiC coatings were approximated 2.17?×?10?3 and 9.52?×?10?3 g s?1, respectively, decreased by 84.1 and 29.6% compared to the uncoated samples. It was mainly attributed to the formation of a SiO2 layer on the surface. The continuous SiO2 molten film formed via the PC–SiC oxidation generates a sealing mechanism which can be an obstacle against the oxygen diffusion and hinder more ablation. This is while discontinuous SiO2 film formed from the thin SS–SiC cannot protect the graphite effectively. The non-isothermal oxidation test shows that without the SiC coating, the sample weight is lost largely from 25 to 1500 °C, and its weight loss was 2.2% after the TGA. However, after coating, the samples possessed excellent oxidation protection and weight losses of SS–SiC and PC–SiC coatings are down to 1.3 and 0.6%, respectively. The more oxidation of the graphite substrate occurred due to the formation of macrocracks in the coating during the TGA and also the formation of holes on SiO2 glass layer owing to release of CO or CO2. 相似文献