全文获取类型
收费全文 | 496篇 |
免费 | 22篇 |
专业分类
电工技术 | 1篇 |
化学工业 | 100篇 |
金属工艺 | 17篇 |
机械仪表 | 30篇 |
建筑科学 | 8篇 |
能源动力 | 31篇 |
轻工业 | 35篇 |
水利工程 | 1篇 |
石油天然气 | 3篇 |
无线电 | 80篇 |
一般工业技术 | 109篇 |
冶金工业 | 62篇 |
原子能技术 | 3篇 |
自动化技术 | 38篇 |
出版年
2024年 | 2篇 |
2023年 | 9篇 |
2022年 | 14篇 |
2021年 | 18篇 |
2020年 | 14篇 |
2019年 | 11篇 |
2018年 | 20篇 |
2017年 | 24篇 |
2016年 | 13篇 |
2015年 | 5篇 |
2014年 | 21篇 |
2013年 | 28篇 |
2012年 | 24篇 |
2011年 | 19篇 |
2010年 | 20篇 |
2009年 | 15篇 |
2008年 | 18篇 |
2007年 | 18篇 |
2006年 | 17篇 |
2005年 | 13篇 |
2004年 | 11篇 |
2003年 | 14篇 |
2002年 | 12篇 |
2001年 | 11篇 |
2000年 | 13篇 |
1999年 | 5篇 |
1998年 | 24篇 |
1997年 | 10篇 |
1996年 | 9篇 |
1995年 | 10篇 |
1994年 | 3篇 |
1993年 | 8篇 |
1992年 | 7篇 |
1991年 | 10篇 |
1990年 | 5篇 |
1989年 | 2篇 |
1988年 | 8篇 |
1987年 | 3篇 |
1986年 | 4篇 |
1985年 | 3篇 |
1984年 | 4篇 |
1983年 | 6篇 |
1982年 | 3篇 |
1981年 | 2篇 |
1979年 | 2篇 |
1976年 | 2篇 |
1975年 | 1篇 |
1973年 | 2篇 |
1957年 | 1篇 |
排序方式: 共有518条查询结果,搜索用时 20 毫秒
81.
Aparna Dixit Syed Imteyaz Alam Ram Kumar Dhaked Lokendra Singh 《Journal of food science》2006,71(3):M121-M125
ABSTRACT: A neurotoxigenic Clostridium sp. (RKD) isolated from intestine of decaying fish produced a neurotoxin that was neutralized by botulinum antitoxin (A+B+E) when tested by mouse protection bioassay. An amplicon of expected size (approximately 700 bp) was generated with primers specific for BoNT/B. Toxin was maximally released in the culture supernatant in the late stationary phase and was dependent on media composition. Growth was optimal in trypticase peptone yeast-extract glucose (TPYG) medium in a pH range of 7.5 to 8.0 and at a temperature between 35°C to 40°C while toxin production was optimum at 37°C (3 to 4 × 103 minimum lethal dose per milliliter) without any protease treatment. There was no correlation between growth and toxin production when cells were grown in media containing different concentrations of NaCl (0% to 5%). Toxin in the culture supernatant was more stable (50% reduction at 50°C in 90 min) than the partially purified fraction. Toxicity was destroyed gradually after increasing the number of freeze-thaw cycles and was almost completely inactivated after 5 cycles. It was completely inactivated by overnight treatment of 1 N NaOH while it retained 1.5% activity with a similar treatment with 1 N HCl. 相似文献
82.
Kedage VV Tilak JC Dixit GB Devasagayam TP Mhatre M 《Critical reviews in food science and nutrition》2007,47(2):175-185
Grapes (Vitis vinifera L.) are a major fruit crop in the world. Grapes seem to confer health benefits due to their antioxidant activity. We have evaluated the antioxidant potential of 11 grapes varieties from India and nearby Asian countries. The assays employed involve different levels of antioxidant action like ferric reducing antioxidant power, radical scavenging by 1,1-diphenyl-2-picrylhydrazyl, ferrylmyoglobin/2,2'-azobis-3-ethylbenzthiazoline-6-sulfonic acid, oxygen radical absorbance capacity (ORAC), and inhibition of lipid peroxidation. The total phenolic and flavonoids contents were also estimated. Our study indicates that cv. Mango is the most potent followed by Sharad Seedless. Ethanolic extracts were found to be more effective than aqueous extracts. Cv. Sharad Seedless, Mango, and Manikchaman also had high ORAC values. Their HPLC analysis showed the presence of various antioxidant polyphenols. In conclusion our studies identified some varieties of grapes with high antioxidant activities and showed that their high antioxidant potential may be due to their phenolic and flavonoid contents. 相似文献
83.
Practical application of aligned carbon nanotubes (ACNTs) would have to be determined by a matter of its economical and large-scale
preparation. In this study, neem oil (also named Margoaa oil, extracted from the seeds of the neem--Azadirachta indica) was used as carbon source to fabricate the bundles of ACNTs. ACNTs have been synthesized by spray pyrolysis of neem oil
and ferrocene mixture at 825°C. The major components of neem oil are hydrocarbon with less amount of oxygen, which provided
the precursor species in spray pyrolysis growth of CNTs. The bundles of ACNTs have been grown directly inside the quartz tube.
The as-grown ACNTs have been characterized through Raman spectroscopy, scanning and transmission electron microscopic (SEM/TEM)
techniques. SEM images reveal that the bundles of ACNTs are densely packed and are of several microns in length. High-resolution
TEM analysis reveals these nanotubes to be multi-walled CNTs. These multi-walled CNTs were found to have inner diameter between
15 and 30 nm. It was found that present technique gives high yield with high density of bundles of ACNTs. 相似文献
84.
ABSTRACT De-ashing of Indian coal samples from Bhojudih, Mandaman and Kusumunda has been studied using High Gradient Magnetic Separation (HGMS(. Coating of the ash particles with magnetite or blue dust brings down the operating magnetic field considerably. The flow velocity has a significant effect on the removal as well as Heat Value Recovery (HVR). 相似文献
85.
S. Dixit S.K. Purshottam S.K. Khanna 《Food additives & contaminants. Part A, Chemistry, analysis, control, exposure & risk assessment》2013,30(9):1227-1231
Curcumin, the principal curcuminoid of turmeric, is responsible for its yellow colour and serves as a measure of turmeric quality. The Prevention of Food Adulteration (PFA) Act of India allows only Curcuma longa L. for the production of turmeric powder and prohibits addition of any foreign matter/artificial colour, but it does not specify a minimum curcumin content. The present surveillance was undertaken to study the quality of loose versus branded turmeric powders vis-à-vis curcumin content and the presence of unwarranted extraneous colours from city markets in India using a newly developed two-dimensional high-performance thin-layer chromatography (2D-HPTLC) method. The results show that curcumin content in branded samples ranged from 2.2% to 3.7%, while non-branded samples had from 0.3% to 2.6%. Though none of the branded turmeric powders contained artificial colours, 17% of loose powders showed the presence of extraneous colour metanil yellow, in the range 1.0–8.5 mg g?1, which may pose health threats. Low curcumin content in the analysed samples may be due to mixing of other curcuma species or their curcumin-depleted matrices and foreign starches as cheaper alternatives. This is supported by the fact that major Indian turmeric trade types are known to possess curcumin contents ranging from 2.1% to 8.6%, with an average of 4.8%. There is thus an urgent need to prescribe realistic curcumin limits for turmeric powder, otherwise there is no obligation on the part of traders to stick to any minimum levels and consumers will keep on getting this nutrient-depleted household spice. 相似文献
86.
Comparative performance analysis of cogeneration gas turbine cycle for different blade cooling means
The paper compares the thermodynamic performance of MS9001 gas turbine based cogeneration cycle having a two-pressure heat recovery steam generator (HRSG) for different blade cooling means. The HRSG has a steam drum generating steam to meet coolant requirement, and a second steam drum generates steam for process heating. Gas turbine stage cooling uses open loop cooling or closed loop cooling schemes. Internal convection cooling, film cooling and transpiration cooling techniques employing steam or air as coolants are considered for the performance evaluation of the cycle. Cogeneration cycle performance is evaluated using coolant flow requirements, plant specific work, fuel utilisation efficiency, power-to-heat-ratio, which are function of compressor pressure ratio and turbine inlet temperature, and process steam drum pressure. The maximum and minimum values of power-to-heat ratio are found with steam internal convection cooling and air internal convection cooling respectively whereas maximum and minimum values of fuel utilisation efficiency are found with steam internal convection cooling and closed loop steam cooling. The analysis is useful for power plant designers to select the optimum compressor pressure ratio, turbine inlet temperature, fuel utilisation efficiency, power-to-heat ratio, and appropriate cooling means for a specified value of plant specific work and process heating requirement. 相似文献
87.
88.
The superconducting properties of magnesium diboride (MgB2) films prepared by electroless deposition on various substrates including silver, gold and silicon are reported. In this study, MgB2 films were fabricated on silver, gold, and silicon using an electroless plating technique, while controlling the redox potential to improve the deposition quality. The structure, morphology, and superconducting properties of the samples were investigated using X-ray diffraction, magnetometry, scanning electron microscopy, and Raman spectroscopy. X-ray diffraction and Raman spectroscopy confirmed that the films are polycrystalline MgB2 but also contain some impurity phases. All the MgB2 films show superconducting transitions near 39 K, the value for bulk MgB2, with the superconducting volume fraction ranging from approximately 1 to 2%. We find a strong dependence of film quality with the oxidation potential of the bath. 相似文献
89.
Global concern for depleting fossil fuel reserves have been compelling for evolving power generation options using renewable energy sources. The solar energy happens to be a potential source for running the power plants among renewable energy sources. Integrated Solar Combined Cycle(ISCC) power plants have gained popularity among the thermal power plants. Traditional ISCC power plants use Direct Steam Generation(DSG) approach. However, with the DSG method, the ISCC plant’s overall thermal effici... 相似文献
90.
Payel Choudhury Rup Narayan Ray Tarun Kanti Bandyopadhyay Onkar Nath Tiwari Biswanath Bhunia 《International Journal of Hydrogen Energy》2021,46(31):16815-16822
Due to the growing demand for energy in the present-day world, it is obligatory to look for alternative sources of renewable energy. The derivation of power from microbial fuel cells (MFCs) has developed at the vanguard of the alternative source of renewable energy through the concomitant treatment of wastewater. Hence, the process development of MFC is obligatory for creating a sustainable source of renewable energy through the treatment of wastewater. To that end, an attempt was taken in the present study for sustainable power generation from single chamber microbial fuel cell (SCMFC) using Pseudomonas aeruginosa-MTCC-7814. The experiments were carried out in a batch process for 15 days with real dairy wastewater (RDW) having initial chemical oxygen demand (COD) of 8000 mg/L. The open-circuit voltage (OCV) found after 72 h of batch operation was 658 mV, which was maximum within the batch operation. The columbic efficiency (CE) of the batch process was found to be 46.59%. The maximum specific growth rate (μmax) of Pseudomonas aeruginosa-MTCC-7814 was found to be 0.432 day?1 during batch operation. However, saturation constant (Ks) and inhibition coefficient (Ki) were calculated as 608.74 mg/L, and 6582 mg/L, respectively. The maximum current density (Imax) and saturation constant (Kc) predicted from batch kinetics study were 132 mA/m2 and 321 mg/L, respectively, which has resemblance with the data obtained from experiments. The maximum current density and power density from experiments were found to be 161 mA/m2 and 34.82 mW/m2, respectively. Results showed that a higher power density and current density values were obtained from the present study as compared to the earlier reports that utilized wastewater as the substrate for the MFC. Thus, the study suggests that Pseudomonas aeruginosa, (MTCC-7814) can be used as a promising biocatalyst in MFC for sustainable power generation through the utilization of wastewater treatment. 相似文献