全文获取类型
收费全文 | 2398篇 |
免费 | 145篇 |
国内免费 | 25篇 |
专业分类
电工技术 | 34篇 |
综合类 | 10篇 |
化学工业 | 593篇 |
金属工艺 | 66篇 |
机械仪表 | 105篇 |
建筑科学 | 116篇 |
矿业工程 | 3篇 |
能源动力 | 83篇 |
轻工业 | 212篇 |
水利工程 | 29篇 |
石油天然气 | 19篇 |
武器工业 | 3篇 |
无线电 | 300篇 |
一般工业技术 | 384篇 |
冶金工业 | 113篇 |
原子能技术 | 19篇 |
自动化技术 | 479篇 |
出版年
2024年 | 4篇 |
2023年 | 30篇 |
2022年 | 69篇 |
2021年 | 125篇 |
2020年 | 132篇 |
2019年 | 135篇 |
2018年 | 173篇 |
2017年 | 143篇 |
2016年 | 140篇 |
2015年 | 84篇 |
2014年 | 179篇 |
2013年 | 243篇 |
2012年 | 153篇 |
2011年 | 177篇 |
2010年 | 111篇 |
2009年 | 99篇 |
2008年 | 86篇 |
2007年 | 56篇 |
2006年 | 49篇 |
2005年 | 39篇 |
2004年 | 24篇 |
2003年 | 21篇 |
2002年 | 8篇 |
2001年 | 18篇 |
2000年 | 13篇 |
1999年 | 12篇 |
1998年 | 30篇 |
1997年 | 24篇 |
1996年 | 27篇 |
1995年 | 20篇 |
1994年 | 13篇 |
1993年 | 14篇 |
1992年 | 8篇 |
1991年 | 12篇 |
1990年 | 8篇 |
1989年 | 4篇 |
1988年 | 7篇 |
1987年 | 10篇 |
1986年 | 11篇 |
1985年 | 6篇 |
1984年 | 5篇 |
1982年 | 3篇 |
1980年 | 3篇 |
1979年 | 3篇 |
1976年 | 3篇 |
1975年 | 3篇 |
1973年 | 5篇 |
1971年 | 6篇 |
1970年 | 8篇 |
1969年 | 4篇 |
排序方式: 共有2568条查询结果,搜索用时 0 毫秒
101.
Dynamically vulcanized polypropylene/ethylene‐propylene diene monomer/organoclay nanocomposites: Effect of mixing sequence on structural,rheological, and mechanical properties 下载免费PDF全文
Ghasem Naderi Ramin Khosrokhavar Shirin Shokoohi Gholam Reza Bakhshandeh Mir Hamid Reza Ghoreishy 《乙烯基与添加剂工艺杂志》2016,22(3):320-325
Dynamically vulcanized thermoplastic elastomer (TPE) nanocomposites based on polypropylene (PP), ethylene‐propylene diene monomer (EPDM) and cloisite 15A were prepared via direct melt mixing in a co‐rotating twin‐screw extruder. The mixing process was carried out with optimized processing parameters (barrel temperature = 180°C; screw speed = 150 rpm; and feeding rate = 0.2 kg/hr). The formulation used to prepare the nanocomposites was fixed to 75/20/5 (PP/EPDM/Cloisite©15A), expressed in mass fraction. Effect of mixing sequence on the properties of vulcanized and unvulcanized (TPE) nanocomposites prepared under similar conditions was investigated using X‐ray diffraction (XRD) and a tensile testing machine. Results showed that the sequence of mixing does affect the properties of final TPE nanocomposites. Accordingly, nanocomposite samples prepared through mixing the preblended PP/clay masterbatch with EPDM phase, show better clay dispersion within the polymer matrix. J. VINYL ADDIT. TECHNOL., 22:320–325, 2016. © 2014 Society of Plastics Engineers 相似文献
102.
This study presents a new semi-analytical method to simulate the two-phase liquid transport in hydraulic fractures (HF) and matrix system, which can be applied to characterize HF attributes and dynamics using the flowback data from hydraulically fractured shale oil wells. The proposed approach includes a fracture model for HF properties calculation and a matrix model capable of considering multiple liquid transport mechanisms in shale nanopores. The proposed method is first validated with the numerical simulation then applied to a field example in Eagle Ford shale. The numerical validation confirms that our method can accurately characterize fracture attributes and closure dynamics by closely estimating the initial fracture permeability, pore-volume, compressibility, and permeability modulus. Furthermore, the analysis results from numerical simulation and a field example both indicate a clear flow enhancement and deficit for oil and water transport, respectively, due to the slippage effect and variation of fluid properties inside nanopores. 相似文献
103.
The objective of this study is to develop a new biocomposite material with high deformation ability. In this regard, the thermal, rheological, and thermophysical properties of this new composite were characterized as a function of temperature and filler concentration. High density polyethylene (HDPE) was the matrix of this new composite which was reinforced with six sawdust concentrations 0%, 20%, 30%, 40%, 50%, and 60%. Maleic anhydride grafted polyethylene (PE‐g‐MA) was used as coupling agent. Addition of sawdust with PE‐g‐MA increased significantly the complex viscosity, the storage modulus (G′), and loss modulus (G″) of the matrix. The superposition of the complex viscosity curves using temperature dependent shift factor, allowed the construction of a viscosity master curve covering a wide range of temperatures. Arrhenius law was used for the relationship of the shift factor to temperature. Furthermore, method of Van Gurp and Palmen (tan delta vs. G*) is also used to control the time–temperature superposition. The experimental results can be well fitted with the cross rheological model which allowed the prediction of the thermorheological properties of the composites over a broad frequency range. By increasing wood concentration, both the activation energy and relaxation time for the biocomposites determined using, respectively, the Arrhenius law and the cole–cole rule increased. By contrast, specific heat of the matrix decreased with sawdust addition while its dimensional stability improved. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40495. 相似文献
104.
Sanaz Naghibi Hamid Reza Madaah Hosseini Mohammad Ali Faghihi Sani Mohammad Ali Shokrgozar Morteza Mehrjoo 《Ceramics International》2014
TiO2 nanoparticles (NPs) were synthesized by hydrothermal assisted sol–gel technique. In the next step, as-synthesized NPs were modified by poly ethylene glycol (PEG). Then, folic acid (FA) was conjugated to TiO2–PEG. Finally, Doxorubicin (Dox) as an anticancer drug was loaded on as-prepared TiO2–PEG–FA nanocarrier. The optimization of TiO2 and FA concentration and the influence of ultraviolet (UV) irradiation on photocatalytic activity of nanocarrier and Dox loaded carrier were assessed by utilizing the 3-(4,5-dimethylthiazol-2yl)-2,5-diphenyltetrazolium bromide (MTT)-assay method. 相似文献
105.
106.
Mohammed M. Al-Najjar S. Halim Hamid Esam Z. Hamad 《Polymer Engineering and Science》1996,36(16):2083-2087
Low-molecular-weight polystyrene was nitrated to different levels. The nitrated polystyrene was blended with different molecular weights of poly(acrylic acid), PAA. The glass transition temperatures (Tg) for the mixtures were investigated by differential scanning calorimetry. A single Tg was observed for all blends, indicating single-phase blends. In general, it was found that the Tg increases with molecular weight of PAA. The Tg values of the blends showed a positive deviation from the linear average Tg as a result of strong hydrogen bonding between the segments of the component polymers. The observed Tg values were not adequately represented by simple predictive equations or by single-parameter fitting equations. However, two-parameter fitting equations gave a reasonable representation of the data. 相似文献
107.
Tyler N. Kambis Hamid R. Shahshahan Paras K. Mishra 《International journal of molecular sciences》2022,23(3)
Metabolic remodeling is at the heart of diabetic cardiomyopathy. High glycemic fluctuations increase metabolic stress in the type 1 diabetes mellitus (T1DM) heart. There is a lack of understanding on how metabolites and genes affect metabolic remodeling in the T1DM heart. We hypothesize that differential expression of metabolic genes and metabolites synergistically influence metabolic remodeling preceding T1DM cardiomyopathy. To test our hypothesis, we conducted high throughput analysis of hearts from adult male hyperglycemic Ins2+/− (Akita) and littermate normoglycemic Ins2+/+ (WT) mice. The Akita mouse is a spontaneous, genetic model of T1DM that develops increased levels of consistent glycemic variability without the off-target cardiotoxic effects present in chemically- induced models of T1DM. After validating the presence of a T1DM phenotype, we conducted metabolomics via LC-MS analysis and genomics via next-generation sequencing in left ventricle tissue from the Akita heart. Ingenuity Pathway Analyses revealed that 108 and 30 metabolic pathways were disrupted within the metabolomics and genomics datasets, respectively. Notably, a comparison between the two analyses showed 15 commonly disrupted pathways, including ketogenesis, ketolysis, cholesterol biosynthesis, acetyl CoA hydrolysis, and fatty acid biosynthesis and beta-oxidation. These identified metabolic pathways predicted by the differential expression of metabolites and genes provide the foundation for understanding metabolic remodeling in the T1DM heart. By limited experiment, we revealed a predicted disruption in the metabolites and genes behind T1DM cardiac metabolic derangement. Future studies targeting these genes and metabolites will unravel novel therapies to prevent/improve metabolic remodeling in the T1DM heart. 相似文献
108.
Recent Developments in Predicting Impact and Shock Sensitivities of Energetic Materials (英) 总被引:1,自引:0,他引:1
Mohammad Hossein Keshavarz Arash Shokrolahi Karim Esmailpoor Abbas Zali Hamid Reza Hafizi Jamshid Azarniamehraban 《含能材料》2008,16(1):113-120
Empirical, quantum mechanical and artificial neural network methods are three usual methods in recent years that were used to predict sensitivity of different classes of high explosives. Some recent developments in predicting sensitivity by various methods are reviewed and discussed for various classes of energetic materials. 相似文献
109.
Mahsa Barzegar Rabi Behrooz Hamid Reza Mansouri Saeed Kazemi Najafi Linda F. Lorenz Charles R. Frihart 《Journal of the American Oil Chemists' Society》2020,97(12):1371-1383
Canola is widely grown in the northern latitudes for its vegetable oil, generating large quantities of residual, low value canola flour used as animal feed. The common wood adhesive poly(diphenylmethylene diisocyanate) (pMDI) should react with the wide variety of functional groups in proteins. Therefore, it would seem that canola flour with added pMDI could be an effective adhesive. Two main questions are addressed in this study: How do the wood adhesive properties of canola flour compare to the better-studied soy flour? How well do proteins, which contain an abundance of functional groups, cure with the very reactive pMDI? These questions were addressed using the small-scale adhesive strength test ASTM D-7998, with various adhesive formulations and bonding conditions for canola flour plus pMDI compared to soy adhesives. The more challenging wet cohesive bond strength was emphasized because the dry strengths were usually very good. Generally, soy adhesives were better than canola ones, as was the polyamidoamine-epichlorohydrin cross-linker compared to pMDI, but these generalizations can be altered by the conditions selected. Three-ply plywood tests supported the small-scale test results. 相似文献
110.
Low temperature sintering of barium titanate ceramics assisted by addition of lithium fluoride-containing sintering additives 总被引:1,自引:0,他引:1
Hamid Naghib-zadeh Carsten Glitzky Ilona Drfel Torsten Rabe 《Journal of the European Ceramic Society》2010,30(1):81-86
By addition of LiF-containing sintering additives to commercial BaTiO3 powder, more than 98% of the theoretical density was reached at a sintering temperature of 900 °C both on powder compacts and laminates. Dielectric measurements were performed on ceramic samples in the temperature and frequency ranges from −20 °C to 125 °C and from 103 to 106 Hz, respectively. High relative permittivity (r 3160) and low dielectric loss (tan δ 0.014) were measured for tapes of the favoured material. The breakdown strength for tapes with a thickness of about 80 μm is 30 kV/mm. The microprobe analysis showed, that no interfacial reaction between the dielectric layer and the Ag-electrode had occurred.The newly developed barium titanate ceramics completely densifying at 900 °C turned out to be promising for integration of buried capacitors in LTCC multilayers. 相似文献