全文获取类型
收费全文 | 1355篇 |
免费 | 53篇 |
国内免费 | 7篇 |
专业分类
电工技术 | 18篇 |
化学工业 | 308篇 |
金属工艺 | 29篇 |
机械仪表 | 32篇 |
建筑科学 | 38篇 |
矿业工程 | 2篇 |
能源动力 | 96篇 |
轻工业 | 115篇 |
水利工程 | 19篇 |
石油天然气 | 9篇 |
无线电 | 161篇 |
一般工业技术 | 333篇 |
冶金工业 | 83篇 |
原子能技术 | 21篇 |
自动化技术 | 151篇 |
出版年
2023年 | 13篇 |
2022年 | 30篇 |
2021年 | 46篇 |
2020年 | 31篇 |
2019年 | 35篇 |
2018年 | 60篇 |
2017年 | 46篇 |
2016年 | 54篇 |
2015年 | 35篇 |
2014年 | 44篇 |
2013年 | 113篇 |
2012年 | 63篇 |
2011年 | 79篇 |
2010年 | 66篇 |
2009年 | 79篇 |
2008年 | 67篇 |
2007年 | 55篇 |
2006年 | 31篇 |
2005年 | 23篇 |
2004年 | 16篇 |
2003年 | 24篇 |
2002年 | 25篇 |
2001年 | 19篇 |
2000年 | 12篇 |
1999年 | 16篇 |
1998年 | 13篇 |
1997年 | 15篇 |
1996年 | 14篇 |
1995年 | 10篇 |
1994年 | 14篇 |
1993年 | 11篇 |
1992年 | 14篇 |
1991年 | 8篇 |
1990年 | 6篇 |
1989年 | 11篇 |
1988年 | 18篇 |
1987年 | 12篇 |
1986年 | 13篇 |
1985年 | 16篇 |
1984年 | 16篇 |
1983年 | 20篇 |
1982年 | 15篇 |
1981年 | 22篇 |
1980年 | 15篇 |
1979年 | 9篇 |
1978年 | 13篇 |
1977年 | 8篇 |
1976年 | 11篇 |
1975年 | 13篇 |
1974年 | 8篇 |
排序方式: 共有1415条查询结果,搜索用时 995 毫秒
61.
As part of a study of slag deposit formation in pulverized-coal-fired boilers, apparent contact angles and adhesion strengths of molten mineral drops contacted with cooler oxidized steel substrates have been investigated. High-speed photography indicated that freezing of the interface between the molten drop and metal surface occurred in milliseconds. Adherence occurred between an oxide film on the metal and the drop, adherence was weak on stainless steels, and particles of oxide film were broken away from the substrate when the drops were sheared off. Higher substrate temperatures gave increased adhesion, with a larger area of strong interaction between the oxide and the drop interface and less area of weak interaction. Addition of compounds to lower the liquidus temperature of the drop gave increased adherence. Pyrite drops were converted to mainly pyrrhotite on melting and showed a high degree of wetting and adherence to the oxidized steel even at low temperatures. 相似文献
62.
Fatty acid modified polyurethane dispersion for surface coatings: Effect of fatty acid content and ionic content 总被引:1,自引:0,他引:1
Ashish Patel Chintankumar Patel M.G. Patel Mehul Patel Ashok Dighe 《Progress in Organic Coatings》2010
The higher molecular weight fatty acid modified polyurethane–urea dispersions (PUDs) were prepared with effective utilization of fatty acid and ionic emulsifier. The PUDs were prepared using oligomer of linoleic fatty acid, dimethylol propionic acid (DMPA), linear polyester diol, isophorone diisocyanate (IPDI), triethylamine (TEA) and ethylenediamine (EDA) by prepolymer mixing method. Resultant PUDs had so-called controlled branched polymer structures. To incorporate fatty acid residues in the backbone of the polyurethane two types of oligomers were used which were synthesized by esterifying linoleic acid and phthalic anhydride (PA) with different monomers having different hydroxyl functionality i.e. trimethylol propane (TMP), pentaerythritol and neopentyl glycol (NPG). The oligomers were mixed with linear polyester diol in different proportions and used as polyol part in prepolymer for PUDs. Various compositional variations such as type of oligomer, content of oligomer and ionic emulsifier were studied for stability and compatibility with water. The PUDs were also examined by FTIR, AFM, GPC, particle size analyzer, viscometer, TGA, DMA and tensile tester to analyze structures and properties. Chemical, water and corrosion resistances of the dried films were also evaluated to study the effect of oligomer content in modified PUDs. These properties are found to be significantly affected by the content and type of oligomer as well as ionic content in the polymer. 相似文献
63.
Garrett Jones Tae Jin Lee Joshua Glass Grace Rountree Lane Ulrich Amy Estes Mary Sezer Wenbo Zhi Shruti Sharma Ashok Sharma 《International journal of molecular sciences》2022,23(4)
The tear film is a multi-layer fluid that covers the corneal and conjunctival epithelia of the eye and provides lubrication, nutrients, and protection from the outside environment. Tear fluid contains a high concentration of proteins and has thus been recognized as a potential source of biomarkers for ocular disorders due to its proximity to disease sites on the ocular surface and the non-invasive nature of its collection. This is particularly true in the case of dry eye disease, which directly impacts the tear film and its components. Proteomic analysis of tear fluid is challenging mainly due to the wide dynamic range of proteins and the small sample volumes. However, recent advancements in mass spectrometry have revolutionized the field of proteomics enabling unprecedented depth, speed, and accuracy, even with small sample volumes. In this study using the Orbitrap Fusion Tribrid mass spectrometer, we compared four different mass spectrometry workflows for the proteomic analysis of tear fluid collected via Schirmer strips. We were able to establish a method of in-strip protein digestion that identified >3000 proteins in human tear samples from 11 healthy subjects. Our method offers a significant improvement in the number of proteins identified compared to previously reported methods without pooling samples. 相似文献
64.
Hemangi G. Chidley Ram S. Kulkarni Keshav H. Pujari Ashok P. Giri Vidya S. Gupta 《Food chemistry》2013
Alphonso is a highly favoured and exported mango cultivar among the vast mango germplasm of India. Being a climacteric fruit, ethylene plays an important role in ripening of mango. For deeper understanding of effect of pre-climacteric ethylene treatment on volatile profiles of Alphonso mango, 26 volatiles were tracked through six ripening stages of pulp and skin of ethylene-treated and control Alphonso fruits. The study revealed accelerated ripening in terms of early appearance of ripening-specific compounds, lactones and mesifuran, upon ethylene treatment. While the level of lactones remained unaffected, the mesifuran level vastly increased upon ethylene treatment. Skin showed high terpene content while pulp had higher amount of lactones compared to skin. This work points towards involvement of ethylene as a natural hormone in the biosynthesis of lactones and furanones in naturally ripened fruits; whereas, an increase in the terpene level during ripening appears to be independent of ethylene. 相似文献
65.
Adsorption of ciprofloxacin and its role for stabilizing multi-walled carbon nanotubes and characterization 总被引:1,自引:0,他引:1
S. Ashok Kumar 《Materials Letters》2009,63(21):1830-1833
In this study, multi-walled carbon nanotubes (MWCNTs) were dispersed in an aqueous solution using ciprofloxacin (CF) without chemical modification. We found that CF is a useful stabilizer for MWCNTs and the dispersions were stable for more than one month. Scanning electron microscopy, Uv-visible spectroscopy and cyclic voltammetry (CV) showed MWCNTs coated with CF molecules. Dry film of MWCNTs/CF was prepared and characterized by SEM, Uv-vis and CV. MWCNTs/CF dry film can be used as a biocompatible platform for other applications including protein and enzyme immobilization. 相似文献
66.
67.
Suresh Bhalla Praveen Kumar Ashok Gupta Tushar K. Datta 《Canadian Metallurgical Quarterly》2009,22(4):373-382
The electromechanical impedance technique employs surface-bonded lead zirconate titanate piezoelectric ceramic patches as impedance transducers for structural health monitoring and nondestructive evaluation. The patches are bonded to the monitored structures using finitely thick adhesive bond layer, which introduces shear lag effect, thus invariably influencing the electromechanical admittance signatures. This paper presents a new simplified impedance model to incorporate shear lag effect into electromechanical admittance formulations, both one-dimensional and two-dimensional. This provides a closed-form analytical solution of the inverse problem, i.e. to derive the true structural impedance from the measured conductance and susceptance signatures, thus an improvement over the existing models. The influence of various parameters (associated with the bond layer) on admittance signatures is investigated using the proposed model and the results compared with existing models. The results show that the new model, which is far simpler than the existing models, models the shear lag phenomenon reasonably well besides providing direct solution of a complex inverse problem. 相似文献
68.
Sangamesh G. Kumbar Anandrao R. Kulkarni Ashok M. Dave Tejraj M. Aminabhavi 《应用聚合物科学杂志》2001,82(11):2863-2866
This article presents our preliminary experimental data on the release kinetics and encapsulation efficiency of urea formaldehyde (UF) crosslinked matrices of starch (St), guar gum (GG), and starch + guar gum (St + GG) for the controlled release of solid (chlorpyrifos) and liquid (neem seed oil) pesticides. The data reveal variable release rates in relation to the polymer type and especially the pesticide type. It is possible to slow the release rates of pesticides using cheaply available materials such as starch and guar gum. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 2863–2866, 2001 相似文献
69.
Batch sorbitol to sorbose bioconversion by Acetobacter suboxydans using initial sorbitol concentration (S0 = 100 g/L) yielded a productivity of 10.11 g/L‐h and 98.6% conversion in 10 h time. The batch kinetics was then used to develop an unstructured mathematical model. Model parameters were identified using a nonlinear regression technique assisted by a computer program which minimized the deviation between the model predictions and actual batch experimental data. F test indicated 99% confidence on the prediction of model using optimized parameters. The batch model was eventually extrapolated to identify nutrient feeding strategies to maintain constant noninhibitory sorbitol supply and eliminate substrate limitation for fed‐batch fermentation in order to improve the sorbose productivity. The adequacy of the fed‐batch model was established by excellent agreement between experimental data and model simulation (except towards the end of fermentation). 相似文献
70.
Manjima Bhattacharya Riya Chakraborty Arjun Dey Ashok Kumar Mandal Anoop Kumar Mukhopadhyay 《Ceramics International》2013,39(2):999-1009
The present experiments were focused on nanoindentation behaviour and the attendant “micro-pop-in” in a dense (~95% of theoretical) coarse-grain (~20 μm) alumina ceramic as a function of loading rate variations at three constant peak loads in the range of 105–106 μN. Based on the experimental results here we report for the first time, to the best of our knowledge, an increase in intrinsic nano scale contact resistance as well as the nanohardness with the loading rate. These observations were explained in terms of the correlation between the nanoscale plasticity and shear stress active just underneath the nanoindenter. 相似文献