全文获取类型
收费全文 | 249篇 |
免费 | 12篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 3篇 |
综合类 | 1篇 |
化学工业 | 75篇 |
金属工艺 | 8篇 |
机械仪表 | 5篇 |
建筑科学 | 16篇 |
能源动力 | 16篇 |
轻工业 | 19篇 |
石油天然气 | 4篇 |
无线电 | 17篇 |
一般工业技术 | 34篇 |
冶金工业 | 22篇 |
原子能技术 | 8篇 |
自动化技术 | 35篇 |
出版年
2024年 | 2篇 |
2023年 | 11篇 |
2022年 | 8篇 |
2021年 | 16篇 |
2020年 | 15篇 |
2019年 | 11篇 |
2018年 | 14篇 |
2017年 | 10篇 |
2016年 | 11篇 |
2015年 | 6篇 |
2014年 | 9篇 |
2013年 | 24篇 |
2012年 | 6篇 |
2011年 | 10篇 |
2010年 | 10篇 |
2009年 | 26篇 |
2008年 | 22篇 |
2007年 | 10篇 |
2006年 | 6篇 |
2005年 | 2篇 |
2004年 | 2篇 |
2003年 | 5篇 |
2000年 | 1篇 |
1999年 | 1篇 |
1998年 | 5篇 |
1997年 | 2篇 |
1996年 | 5篇 |
1992年 | 3篇 |
1991年 | 1篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1979年 | 1篇 |
1977年 | 3篇 |
1976年 | 1篇 |
排序方式: 共有263条查询结果,搜索用时 375 毫秒
171.
This study presents the application of neural networks (NN) for the modeling of strength enhancement of CFRP (carbon fiber-reinforced plastic) confined concrete cylinders. The proposed NN model is based on experimental results collected from literature. It represents the ultimate strength of concrete cylinders after CFRP confinement which is also given in explicit form in terms of diameter, unconfined concrete strength, tensile strength CFRP laminate and total thickness of CFRP layer used. The accuracy of the proposed NN model is quite satisfactory as compared to experimental results. Moreover the results of proposed NN model are compared with 10 different theoretical models proposed by researchers so far and are found to be by far more accurate. 相似文献
172.
The use of artificial intelligence methods in medical analysis is increasing. This is mainly because the effectiveness of classification and detection systems has improved in a great deal to help medical experts in diagnosing. In this paper, we investigate the performance of an artificial immune system (AIS) based fuzzy k-NN algorithm to determine the heart valve disorders from the Doppler heart sounds. The proposed methodology is composed of three stages. The first stage is the pre-processing stage. The feature extraction is the second stage. During feature extraction stage, Wavelet transforms and short time Fourier transform were used. As next step, wavelet entropy was applied to these features. In the classification stage, AIS based fuzzy k-NN algorithm is used. To compute the correct classification rate of proposed methodology, a comparative study is realized by using a data set containing 215 samples. The validation of the proposed method is measured by using the sensitivity and specificity parameters. 95.9% sensitivity and 96% specificity rate was obtained. 相似文献
173.
Maizatul S. Shaharun Hilmi Mukhtar Binay K. Dutta 《Chemical engineering science》2008,63(11):3024-3035
Solubilities of carbon monoxide and hydrogen in propylene carbonate (PC), biphasic mixture of PC and dodecane (1:1 v/v) and thermomorphic (or temperature dependent) multicomponent solvent (TMS)-system consisting of PC, dodecane and 1,4-dioxane were measured over the temperature and pressure range of 298–343 K and 0.1–1.5 MPa, respectively, in a high pressure solubility cell. The measured solubilities were correlated by a temperature-dependent Henry's law constant and interpreted by activity coefficient models based on the regular solution theory (RST) with Yen and McKetta extension for polar solvents as well as by the UNIFAC group contribution method. The experimental data showed a very good fit in terms of Henry's law constant except for H2–PC and CO–PC binaries. The RST-based model, that did not involve any adjustable constant, could predict the experimental solubility to within ±11.0% error. The UNIFAC model worked better with the interaction parameters computed as a linear function of temperature using a part of the experimental solubility data set. The accuracy of prediction was found to be within a maximum error of ±8.5%. The TMS system shows higher affinity for CO and H2, which is comparable to the single phase PC. The experimental solubilities in the liquids are substantially larger than those in most other hydroformylation solvents thereby establishing its advantage over the alternative solvents for industrial use. Liquid–liquid equilibrium for the TMS system consisting of PC, dodecene and 1,4-dioxane system was also measured at 298, 353 and 373 K. 相似文献
174.
175.
Mukhtar Ahmed RANA 《核技术(英文版)》2008,19(3):174-177
It would be very interesting to develop a picture about removal of atoms from the radiation damaged paths or latent nuclear tracks and undamaged bulk material in track detectors. Here, theory of chemical etching is described briefly and a new model for chemical etching along radiation damaged paths in solids is developed based on basic scientific facts and valid assumptions. Dependence of chemical etching on radiation damage intensity and etching conditions is discussed. A new parameter for etching along radiation damaged paths is introduced, which is useful for investigation of relationship between chemical etchability and radiation damage in a solid. Results and discussion presented here are also useful for further development of nuclear waste immobilization. 相似文献
176.
Rabi Ebrahim Mukhtar Yeleuov Ainur Issova Serekbol Tokmoldin Alex Ignatiev 《Nanoscale research letters》2014,9(1):286
Fabrication of microporous structures for the anode of a thin film solid oxide fuel cell (SOFC(s)) using controlled etching process has led us to increased power density and increased cell robustness. Micropores were etched in the nickel anode by both wet and electrochemical etching processes. The samples etched electrochemically showed incomplete etching of the nickel leaving linked nickel islands inside the pores. Samples which were wet- etched showed clean pores with no nickel island residues. Moreover, the sample with linked nickel islands in the anode pores showed higher output power density as compared to the sample with clean pores. This enhancement is related to the enlargement of the surface of contact between the fuel-anode-electrolyte (the triple-phase boundary). 相似文献
177.
Syeda Masooda Mukhtar 《Creativity & Innovation Management》1996,5(1):79-81
The aim of this paper is to highlight critical issues facing Technology-Based Small Firms by drawing attention to the latest research in this field. In the main, the discussion is based on selected papers presented at the Third High Technology Small Firms Conference held at Manchester Business School in September 19951. However, the author does draw upon other literature also in order to place conference findings in a wider context. An overview of current research indicates that securing external funding and formation of external alliances remain at top of the agenda for both Technology-Based Small Firms as well as policy makers. 相似文献
178.
Aisha Abdulkadir Peter A. Leffelaar John O. Agbenin Ken Everlyn Giller 《Nutrient Cycling in Agroecosystems》2013,95(2):231-254
Nutrient balances are useful indicators to assess the sustainability of farming systems. This study study investigates inflow and outflow of major nutrients in urban and periurban production systems in Kano, Nigeria. To this end, 16 households representing three different urban and peri-urban (UPA) farming systems were studied using the MONQI toolbox (formerly known as NUTMON) to calculate nutrient flows and economic performances. The farm nitrogen (N) balance was positive at 56.6, 67.4 and 56.4 kg farm?1 year?1 for commercial garden and crop-livestock (cGCL), commercial gardening and semi-commercial livestock (cGscL) and commercial livestock subsistence field cropping (cLsC) farm types, respectively. The same trend was observed for phosphorus (P) and potassium (K) in all farm types except an annual negative K balance of 16 kg farm?1 in cGCL. Across the different activities within the farms, land uses had positive N (359, 387 and 563 kg N ha?1 year?1) and P (74, 219 and 411 kg P ha?1 year?1) balances for all farm types, but again a negative K balance in cGCL with an average loss of 533 kg K ha?1 year?1. Partial nutrient balances in livestock production indicated a positive balance for all nutrients across the farms types but were slightly negative for P in cLsC. Commercial livestock keeping (cLsC) was economically more profitable than the other farm types with an average annual gross margin (GM) and net cash flow (NCF) of $9,033 and $935. Cropping activities within cGCL and cGscL had GMs of $1,059 and $194 and NCFs of $757 and $206, respectively, but livestock activities in both farm types incurred financial losses. Potassium inputs were limited under vegetable and crop production of cGCL, threatening long-term K nutrient availability in this system. Overall, the results indicated large annual surpluses of N and P in urban and peri-urban vegetable and crop production systems which pose a potential threat when lost to the environment. Appropriate policies should aim at promoting sustainable production through efficient nutrient management in the Kano UPA sector. 相似文献
179.
Meltem Yanılmaz Betül Türel Erbay Ersin Serhatli Abdulkadir Sezai Sarac 《应用聚合物科学杂志》2013,127(6):4957-4966
In this work, a new method, consists of synthesis of urethane acrylate (UA) followed by in situ polymerization of pyrrole using cerium (IV) as an oxidant and UV‐curing of the composites, for preparing polypyrrole–UA (PPy–UA) composite films was described. It appeared that dielectric constants of the composites increased with increasing the PPy content and decreased with increasing the frequency from 10?2 to 107, indicating an interfacial Maxwell–Wagner contribution to the permittivity. An incorporation of a small amount of PPy (15% Py) to UA matrix increased their dielectric constants more than 4 × 104 (41,259) at 10?2 Hz. So, the incorporation of PPy was very effective for enhancing the dielectric properties of UA matrix. Furthermore, the significant enhancement in dielectric properties (loss tangent and dielectric constant) contributes to the improvement in electromagnetic interference shielding efficiency. Composite films were characterized using Fourier transform infrared attenuated total reflectance (FTIR‐ATR) spectrophotometer and 1H‐NMR. It was seen that PPy is blended with the UA matrix at the molecular level through H‐bonding interactions. A linear relationship was also observed between the characteristic groups' absorbances of PPy (from FTIR‐ATR) and dielectric constant values (from dielectric spectrometer). © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2013 相似文献
180.