全文获取类型
收费全文 | 1538篇 |
免费 | 99篇 |
国内免费 | 7篇 |
专业分类
电工技术 | 26篇 |
综合类 | 2篇 |
化学工业 | 338篇 |
金属工艺 | 35篇 |
机械仪表 | 40篇 |
建筑科学 | 36篇 |
矿业工程 | 2篇 |
能源动力 | 103篇 |
轻工业 | 147篇 |
水利工程 | 11篇 |
石油天然气 | 39篇 |
无线电 | 191篇 |
一般工业技术 | 324篇 |
冶金工业 | 77篇 |
原子能技术 | 10篇 |
自动化技术 | 263篇 |
出版年
2024年 | 4篇 |
2023年 | 44篇 |
2022年 | 71篇 |
2021年 | 98篇 |
2020年 | 68篇 |
2019年 | 55篇 |
2018年 | 83篇 |
2017年 | 77篇 |
2016年 | 76篇 |
2015年 | 43篇 |
2014年 | 61篇 |
2013年 | 128篇 |
2012年 | 96篇 |
2011年 | 107篇 |
2010年 | 62篇 |
2009年 | 77篇 |
2008年 | 60篇 |
2007年 | 73篇 |
2006年 | 51篇 |
2005年 | 36篇 |
2004年 | 30篇 |
2003年 | 28篇 |
2002年 | 14篇 |
2001年 | 7篇 |
2000年 | 13篇 |
1999年 | 12篇 |
1998年 | 9篇 |
1997年 | 16篇 |
1996年 | 11篇 |
1995年 | 16篇 |
1994年 | 10篇 |
1993年 | 14篇 |
1992年 | 9篇 |
1991年 | 11篇 |
1990年 | 7篇 |
1989年 | 8篇 |
1988年 | 6篇 |
1987年 | 6篇 |
1986年 | 5篇 |
1985年 | 7篇 |
1984年 | 6篇 |
1983年 | 7篇 |
1982年 | 4篇 |
1981年 | 8篇 |
1980年 | 2篇 |
1977年 | 3篇 |
1976年 | 1篇 |
1974年 | 1篇 |
1973年 | 1篇 |
1970年 | 2篇 |
排序方式: 共有1644条查询结果,搜索用时 15 毫秒
131.
Alka Gupta Ambreen Nisar Shobit Omar Kantesh Balani 《JOM Journal of the Minerals, Metals and Materials Society》2018,70(10):1937-1945
The grain growth kinetics of 8YSZ ceramics processed using spark plasma sintering (SPS) has been investigated in the temperature ranging from 1100°C to 1500°C. The activation energy during SPS densification was obtained as 332 kJ/mol with grain boundary diffusion as a dominant mechanism. Further, the effect of CeO2 on the densification kinetics of 8YSZ ceramic processed via SPS and conventional sintering (CS) has been delineated. The lower grain boundary mobility of CS-processed composites (an order of magnitude lower than SPS) is attributed to the solute drag and lattice distortion mechanism. However, no significant change in the grain boundary mobility was observed with CeO2 addition (~?14.7–43.9?×?10?18 m3/N/s for CS and 107.2–116.7?×?10?18 m3/N/s for SPS) revealing that the defect concentration is nearly constant in 8YSZ. The study highlights the effect of sintering techniques (SPS and CS) and reinforcement (CeO2) on engineering the desired microstructure of 8YSZ ceramic. 相似文献
132.
Semiconducting polyurethane/polypyrrole/polyaniline for microorganism immobilization and wastewater treatment in anaerobic/aerobic sequential packed bed reactors 下载免费PDF全文
Iveth D. Antonio‐Carmona Silvia Y. Martínez‐Amador Hugo Martínez‐Gutiérrez Víctor M. Ovando‐Medina Omar González‐Ortega 《应用聚合物科学杂志》2015,132(28)
The development of new materials for microorganism immobilization is very important in wastewater treatment. In this work polyurethane (PU) foams were modified polymerizing pyrrole and aniline onto their surface by chemical oxidization to obtain polyurethane/polypyrrole (PU/PPy), polyurethane/polyaniline (PU/PANI), and PU/(PPy‐co‐PANI) supports which were used to immobilize microorganisms for municipal wastewater treatment in batch mode and continuous flow using two sequential (anaerobic/aerobic) packed bed reactors (PBR) varying the total hydraulic retention time (HRT). The supports were characterized by Fourier Transform Infrared (FTIR) spectroscopy and Scanning Electron Microscopy (SEM) and tested in chemical oxygen demand (COD) removal during treatment of a municipal wastewater. It was observed from SEM analysis that globular nanostructures of PPy and PPy‐co‐PANI were formed onto the PU surface with average diameters between 100 and 300 nm, which are typical of aqueous polymerization of pyrrole monomer; however irregular nanostructures were observed when PANI was homopolymerized onto the PU foam. Batch wastewater treatment after 14 days showed COD removal efficiencies of 77%, 69%, 78%, and 80% for PU foam, PU/PPy, PU/PANI, and PU/(PPy‐co‐PANI), respectively; which was explained as a function of polymers morphology deposited onto the PU foam surface. Also it was observed from the sequential PBR that for 24 h and 36 h of HRT, 80 and 90% of COD removal can be achieved; respectively.© 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42242. 相似文献
133.
Mohamed F. Elshal Alia M. Aldahlawi Omar I. Saadah J. Philip McCoy 《International journal of molecular sciences》2015,16(12):28998-29010
Loss of tolerance of the adaptive immune system towards indigenous flora contributes to the development of inflammatory bowel diseases (IBD). Defects in dendritic cell (DC)-mediated innate and adoptive immune responses are conceivable. The aim of this study was to investigate the expression of the inhibitory molecules CD200R1 and their ligand CD200 on DCs, to clarify the role of the DCs in the pathogenesis of IBD. Thirty-seven pediatric IBD patients (23 with Crohn’s disease (CD) and 14 with ulcerative colitis (UC)) with mean age 13.25 ± 2.9 years were included. Fourteen age-matched healthy pediatric volunteers (five males and nine females) served as a control group (HC). The percentage of CD11c+ myeloid dendritic cells (mDCs) and CD123+ plasmacytoid DCs (pDCs) expressing CD200R1 and CD200 were evaluated in peripheral blood using flow cytometry and were correlated with routine biochemical, serological markers, serum levels of cytokines and with the percentages of circulating regulatory T cells (Treg) and CD4+ producing IL-17 (Th17). IBD patients showed a significant decrease in the percentage of pDCs and mDCs expressing CD200R1 compared to that of HC. Patients with UC showed increased expressions of the CD200 molecule on pDCs as compared to HC. DCs expressing CD200R1 were found to be correlated positively with Treg and negatively with TH17 and erythrocyte sedimentation rate (ESR). Our findings suggest that IBD is associated with dysregulation in the CD200R1/CD200 axis and that the decrease in DCs expressing CD200R1 may contribute to the imbalance of Th17 and Treg cells and in the pathogenesis of IBD. 相似文献
134.
Intermetallic growth and ball shear behavior of annealed Cu wire bonds on Al have been studied. The shear strength of Cu ball
bonds decreased with time, and ductile fracture was the dominant failure mode from 125°C to 150°C. Al pad peel-off occurred
as the aging temperature was increased above 150°C. The overall Cu/Al intermetallic thickness exhibited parabolic behavior
as a function of time. A linear correlation was established between ball shear strength, metal peel-off occurrence, and intermetallic
growth. The Cu/Al intermetallic growth activation energy was 0.23 eV, and the intermetallics identified in the experiment
were CuAl2 and CuAl. 相似文献
135.
136.
Omar S. Ahmed Charles Tardif Caroline Rouger Vessela Atanasova Florence Richard-Forget Pierre Waffo-Téguo 《Comprehensive Reviews in Food Science and Food Safety》2022,21(2):1161-1197
Mycotoxins are metabolites produced by molds that contaminate food commodities, are harmful to both humans and animals, as well as cause economic losses. Many countries have set regulatory limits and strict thresholds to control the level of mycotoxins in food and feedstuffs. New technologies and strategies have been developed to inhibit toxigenic fungal invasion and to decontaminate mycotoxins. However, many of these strategies do not sufficiently detoxify mycotoxins and leave residual toxic by-products. This review focuses on the use of phenolic compounds obtained from botanical extracts as promising bioagents to inhibit fungal growth and/or to limit mycotoxin yields. The mechanism of these botanicals, legislation concerning their use, and their safety are also discussed. In addition, recent strategies to overcome stability and solubility constraints of phenolic compounds to be used in food and feed stuffs are also mentioned. 相似文献
137.
Khaled Daqrouq Ibrahim N. Abu-Isbeih Omar Daoud Emad Khalaf 《International Journal of Speech Technology》2010,13(2):101-115
This paper investigates the utilization of wavelet filters via multistage convolution by Reverse Biorthogonal Wavelets (RBW)
in high and low pass band frequency parts of speech signal. Speech signal is decomposed into two pass bands of frequency;
high and low, and then the noise is removed in each band individually in different stages via wavelet filters. This approach
provides better outcomes because it does not cut the speech information, which occurs when utilizing conventional thresholding.
We tested the proposed method via several noise probability distribution functions. Subjective evaluation is engaged in conjunction
with objective evaluation to accomplish optimal investigation method. The method is simple but has surprise high quality results.
The method shows superiority over Donoho and Johnstone thresholding method and Birge-Massart thresholding strategy method. 相似文献
138.
A fluidized bed crystallization technology was found to be a feasible method for the reduction of scaling tendency of seawater. Seeded crystallization experiments in a pilot plant fluidized bed crystallizer were conducted. The obtained results for seawater, with initial salinity of 55.75 g/kg and initial pH of 8.23 at a constant temperature of 50 °C, have proven that the Ryznar Stability Index of seawater has been changed dramatically from its initial value of 4.77 (in the range of high scaling potential) to the value of 5.10 (in the range of middle to small scaling potential) over a time period of 180 min. 相似文献
139.
Calculation of the octane number for aromatic hydrocarbons expected to be present in the gasoline range (40-200° C) was carried out by developing a new method using H-nmr spectroscopy and multiparametric regressional analysis. The additivity parameters suggested in the muliparametric regressional analysis are relevant to the chemical formula for mono, di, and poly alkyl substituted benzenes.
Two sets of relevant parameters in two different attempts were suggested to suit the calculation of the octane number of all the possible present aromatic in the gasoline range. The first attempt, gives rise to parametric equation (1) suitable to calculate the octane number for all mono substituted alkyl benzenes. However, application of the developed equation to di, tri, and poly substituted alkyl benzenes gives calculated octane number values, do not agree with the observed values. In the second attempt additional parameters were included in the regression analysis; they are resonance (R), steric (S), and inductive (I) effects. The new developed equation (2) gives calculated octane number values comparable to the observed ones for all the possible and hypothetical aromatics in gasoline. 相似文献
Two sets of relevant parameters in two different attempts were suggested to suit the calculation of the octane number of all the possible present aromatic in the gasoline range. The first attempt, gives rise to parametric equation (1) suitable to calculate the octane number for all mono substituted alkyl benzenes. However, application of the developed equation to di, tri, and poly substituted alkyl benzenes gives calculated octane number values, do not agree with the observed values. In the second attempt additional parameters were included in the regression analysis; they are resonance (R), steric (S), and inductive (I) effects. The new developed equation (2) gives calculated octane number values comparable to the observed ones for all the possible and hypothetical aromatics in gasoline. 相似文献
140.
Diana Villanueva Alma-Delia Cuevas-Rasgado Omar Juárez Adolfo Guzmán-Arenas 《Expert systems with applications》2013,40(2):598-610
In natural language processing (NLP), disambiguation is the procedure used to solve name conflicts of polysemic concepts (different meanings); in fact, phrase disambiguation is a problem not totally solved in NLP. Several disambiguation types exist; for instance, noun disambiguation (bank is a word with several meanings) or when a word is both used as a noun and as a preposition. Work herein reported describes an algorithm and its implementation to disambiguate prepositions in Spanish phrases; some of them are: a {to} (Translation to English are in bold for explanation purposes; they give only one of the senses of the Spanish word, which usually have multiple meanings.), ante {before}, bajo {under}, cabe {fits}, desde {from}, contra {against}, en {in}, por {by}, según {according to}, sin {without}, entre {between}, so {under}, con {with}, hacia {towards}, sobre {about}, hasta {until}, de {of}, tras {after}, para {for}. This tool will be used in a text analyzer (being built) that converts a text document to its corresponding ontology representation, with the goal of allowing another program to use the information to answer non trivial questions (**). 相似文献