全文获取类型
收费全文 | 270篇 |
免费 | 15篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 2篇 |
化学工业 | 93篇 |
金属工艺 | 2篇 |
机械仪表 | 4篇 |
建筑科学 | 6篇 |
能源动力 | 4篇 |
轻工业 | 53篇 |
水利工程 | 2篇 |
石油天然气 | 3篇 |
无线电 | 21篇 |
一般工业技术 | 39篇 |
冶金工业 | 35篇 |
原子能技术 | 4篇 |
自动化技术 | 19篇 |
出版年
2023年 | 3篇 |
2022年 | 18篇 |
2021年 | 19篇 |
2020年 | 4篇 |
2019年 | 8篇 |
2018年 | 5篇 |
2017年 | 8篇 |
2016年 | 16篇 |
2015年 | 6篇 |
2014年 | 6篇 |
2013年 | 13篇 |
2012年 | 12篇 |
2011年 | 8篇 |
2010年 | 14篇 |
2009年 | 12篇 |
2008年 | 12篇 |
2007年 | 10篇 |
2006年 | 12篇 |
2005年 | 10篇 |
2004年 | 5篇 |
2003年 | 9篇 |
2002年 | 8篇 |
2001年 | 2篇 |
2000年 | 3篇 |
1999年 | 1篇 |
1998年 | 4篇 |
1997年 | 4篇 |
1996年 | 7篇 |
1995年 | 4篇 |
1994年 | 2篇 |
1993年 | 4篇 |
1992年 | 5篇 |
1991年 | 1篇 |
1990年 | 4篇 |
1989年 | 3篇 |
1988年 | 3篇 |
1987年 | 3篇 |
1986年 | 1篇 |
1985年 | 2篇 |
1984年 | 1篇 |
1982年 | 4篇 |
1981年 | 1篇 |
1979年 | 1篇 |
1977年 | 2篇 |
1975年 | 1篇 |
1969年 | 1篇 |
1968年 | 3篇 |
1963年 | 1篇 |
1955年 | 1篇 |
排序方式: 共有287条查询结果,搜索用时 15 毫秒
41.
Do behavioral observation scales measure observation? 总被引:1,自引:0,他引:1
G. Latham and K. Wexley (see record 1980-02200-001) have claimed that behavioral observation scales (BOS) pose a simpler task for the rater than do either behaviorally anchored rating scales or graphic rating scales; with BOS, the rater need only observe and record behavior and need not make complex judgments about performance. Research on person memory suggests that recall for behaviors is structured by the same trait inferences and judgments that BOS are designed to avoid. In 2 experiments, 91 undergraduates rated videotaped lectures; data from the 1st experiment were used to construct BOS measuring clarity and speaking style. In the 2nd experiment, Ss used the BOS and a graphic rating scale to rate videotaped lectures in immediate and delayed rating conditions. As expected, the correlations between BOS ratings and judgmental ratings of performance were stronger when demands were placed on rater's recall. It is suggested that recall of behaviors is determined by the degree to which certain behaviors are representative of general judgments made about Ss being rated, and that BOS measure traitlike judgments rather than behavioral observation. (27 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
42.
Magda Borhan El‐Arnaouty Ashraf Maher Abdel Ghaffar Ashraf Abdel Kareem Abdel Baky Sayed Ahmed Shama 《乙烯基与添加剂工艺杂志》2019,25(Z1):E35-E43
Synthesis of carboxymethyl cellulose‐g‐methacrylic acid/acrylamide Poly(CMC/MAAc:AAm) hydrogel was carried out using direct radiation copolymerization technique at ambient temperature. The gel (%) increased with increasing the content of AAm till level off at Poly(CMC/MAAc:AAm) (1/50:50 wt%) hydrogel and the swelling behavior found to be increased with increasing MAAc content in the hydrogel composition up to Poly(CMC/MAAc:AAm) (1/60:40 wt%). The grafting yield, grafting ratio, swelling behavior, and the thermal stability of Poly(CMC/MAAc:AAm) binary system are higher than those reported in our previous study by the same author which described the individual grafting of acrylamide (AAm) and methacrylic acid (MAAc) with different concentration onto carboxymethyl cellulose (CMC) using direct radiation grafting technique. The swelling kinetics and diffusion mechanism indicate that the water penetration obey non‐Fickian transport mechanism. The characterization of the prepared hydrogel was evaluated using Fourier transform infrared, X‐ray diffraction, thermogravimetric analysis, and scanning electron microscopy. The analyses by different analytical tools confirmed the successful grafting of both MAAc and AAm onto CMC. The adsorption capacity of Poly(CMC/MAAc:AAm) (1/60:40 wt%) hydrogel toward metal ions such as Cu+2 and Co+2, dyes such as acid blue dye and methyl green have been investigated. J. VINYL ADDIT. TECHNOL., 25:E35–E43, 2019. © 2017 Society of Plastics Engineers 相似文献
43.
The submitted work discussed the possibility of using two of the most problematic wastes to formulate an added‐value hard wood‐composite (HWC). The lignocellulosic rice straws (RS) fibers (as reinforced filler) and recycled expanded polystyrene foam (PS) wastes (as dispersed polymer matrix), were used to formulated the hard wood product applying the hot press technique. The air dried RS was added to the molten PS at increasing ratios (30–70% mass:mass), and the reached HWC sheet was subjected to tensile strength, water absorption and acoustic resistance characterizations. Based on the experimental data, it was found that increasing the RS contents accompanied with a diminish in the tensile strength value by about 50% at 70% RS compare to that at 30% RS. To improve the adhesion between the hydrophilic filler RS and the hydrophobic PS matrix, maleated PS graft (PS‐g‐MA) was prepared and added at the expanse of the PS content, to formulate an additional wood‐composite (HWCg) aiming to have better mechanical and dimensional stability features. Results obtained indicated that increasing the coupling agent content, keeping the RS added constant, enhance the tensile strength feature in addition, reduced the water absorption for the final products by more than 45%. The data obtained suggested that, it can create added‐value hard wood composites entirely from the two nominated problematic wastes. In addition to the value gained by the environment, the reached hard wood products record acceptable mechanical characterization, dimensional stability and sound resistance properties that qualified it to replace the natural wood in many daily applications. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44770. 相似文献
44.
45.
46.
Orsolya Kinga Gondor Judit Tajti Kamirn ron Hamow Imre Majlth Gabriella Szalai Tibor Janda Magda Pl 《International journal of molecular sciences》2021,22(21)
Although the relationship between polyamines and photosynthesis has been investigated at several levels, the main aim of this experiment was to test light-intensity-dependent influence of polyamine metabolism with or without exogenous polyamines. First, the effect of the duration of the daily illumination, then the effects of different light intensities (50, 250, and 500 μmol m–2 s–1) on the polyamine metabolism at metabolite and gene expression levels were investigated. In the second experiment, polyamine treatments, namely putrescine, spermidine and spermine, were also applied. The different light quantities induced different changes in the polyamine metabolism. In the leaves, light distinctly induced the putrescine level and reduced the 1,3-diaminopropane content. Leaves and roots responded differently to the polyamine treatments. Polyamines improved photosynthesis under lower light conditions. Exogenous polyamine treatments influenced the polyamine metabolism differently under individual light regimes. The fine-tuning of the synthesis, back-conversion and terminal catabolism could be responsible for the observed different polyamine metabolism-modulating strategies, leading to successful adaptation to different light conditions. 相似文献
47.
Louise Jank Magda Targa Martins Juliana Bazzan Arsand Tanara Magalhães Campos Motta Tiago Corrêa Feijó Tamara dos Santos Castilhos Rodrigo Barcellos Hoff Fabiano Barreto Tânia Mara Pizzolato 《Food Analytical Methods》2017,10(7):2152-2164
A screening method for analysis of 46 antibiotics residues, belonging to different classes, such as tetracyclines, sulfonamides, fluoroquinolones, β-lactams, cephalosporins, macrolides and other minority groups was developed and validated for application in bovine milk and bovine, swine, poultry, equine, fish and shrimp meat samples. Sample preparation consists in solvent extraction followed by clean up with C18 bulk and low temperature purification. Instrumental analysis was performed using liquid chromatography coupled to tandem mass spectrometry system. Chromatographic separation was achieved using a C18 column. Mobile phase was composed by methanol and water. The method was validated according to Commission Decision 2002/657/EC criteria. Validation parameters such as specificity and detection capability (CCβ) were determined and considered suitable to the established criteria. Values of CCβ ranged from 1.0 to 50.0 μg L?1 or μg Kg?1, depending on the compound and the matrix. The proposed method has been applied into Brazilian National Residue Control Plan since 2013 for the determination of antibiotic residues. A total of 3833 samples were analyzed until the current date and 13 samples showed positive results with concentrations above the permitted. The method is fast, easy and adequate for high throughput analysis in routine laboratories. 相似文献
48.
49.
Martin Loula Antonín Kaňa Magda Vosmanská Richard Koplík 《Food additives & contaminants. Part A, Chemistry, analysis, control, exposure & risk assessment》2016,33(4):668-673
Rape and other Brassicaceae family plants can accumulate appreciable amounts of thallium from the soil. Because some species of this family are common crops utilised as food for direct consumption or raw materials for food production, thallium can enter the food chain. A useful method for thallium determination is inductively coupled plasma mass spectrometry. The limit of detection (0.2 pg ml–1 Tl or 0.02 ng g–1 Tl, taking in the account dilution during sample decomposition) found in the current study was very low, and the method can be used for ultra-trace analysis. Possible transfer of thallium from rape seed to the rape oil was investigated in two ways. The balance of thallium in rape seed meal (content 140–200 ng g–1 Tl) and defatted rape seed meal indicated that thallium did not pass into the oil (p < 0.05). Moreover, the analyses of thallium in six kinds of edible rape seed oil and three kinds of margarines showed that the amount of thallium in rape seed oil is negligible. 相似文献
50.
Mohammed M. Mehanna Hoda A. Elmaradny Magda W. Samaha 《Drug development and industrial pharmacy》2013,39(5):583-593
Management of extraocular diseases is mainly limited by the inability to provide long-term drug delivery without avoiding the systemic drug exposure and/or affecting the intraocular structures and poor availability of drugs, which may be overcome by prolonging the contact time with the ocular system, for instance with liposomes. Development and optimization of reverse phase evaporation ciprofloxacin (CPF) HCl liposomes for ocular drug delivery was carried out using a 25 full factorial design based on five independent variables. The effects of the studied parameters on drug entrapment efficiency (EE), particle size, and percentage of drug released after 1 and 10 h were investigated. The results obtained pointed out that the molar concentration of cholesterol was the predominant factor that increased the EE% of the drug and the particle size responses. The percentage of drug released after 1 h was significantly controlled by the initial CPF concentration while that after 10 h was controlled by molar cholesterol concentration. The designed liposomes had average particle sizes that ranged from 2.5 to 7.23 μm. In addition, liposomes revealed a fast release during the first hour followed by a more gradual drug release during the 24-h period according to Higuchi diffusion model. 相似文献