全文获取类型
收费全文 | 430篇 |
免费 | 41篇 |
专业分类
电工技术 | 3篇 |
化学工业 | 164篇 |
金属工艺 | 3篇 |
机械仪表 | 10篇 |
建筑科学 | 10篇 |
能源动力 | 16篇 |
轻工业 | 111篇 |
无线电 | 16篇 |
一般工业技术 | 42篇 |
冶金工业 | 18篇 |
原子能技术 | 2篇 |
自动化技术 | 76篇 |
出版年
2023年 | 6篇 |
2022年 | 25篇 |
2021年 | 44篇 |
2020年 | 15篇 |
2019年 | 19篇 |
2018年 | 18篇 |
2017年 | 15篇 |
2016年 | 14篇 |
2015年 | 20篇 |
2014年 | 20篇 |
2013年 | 25篇 |
2012年 | 32篇 |
2011年 | 37篇 |
2010年 | 23篇 |
2009年 | 29篇 |
2008年 | 23篇 |
2007年 | 11篇 |
2006年 | 15篇 |
2005年 | 10篇 |
2004年 | 8篇 |
2003年 | 11篇 |
2002年 | 6篇 |
2001年 | 2篇 |
2000年 | 1篇 |
1999年 | 4篇 |
1998年 | 6篇 |
1997年 | 4篇 |
1996年 | 3篇 |
1995年 | 2篇 |
1994年 | 1篇 |
1993年 | 3篇 |
1992年 | 1篇 |
1991年 | 2篇 |
1989年 | 1篇 |
1988年 | 3篇 |
1987年 | 3篇 |
1986年 | 2篇 |
1985年 | 1篇 |
1984年 | 3篇 |
1983年 | 1篇 |
1981年 | 1篇 |
1974年 | 1篇 |
排序方式: 共有471条查询结果,搜索用时 15 毫秒
71.
Sulfolobus solfataricus protein disulphide oxidoreductase: insight into the roles of its redox sites
Limauro D Saviano M Galdi I Rossi M Bartolucci S Pedone E 《Protein engineering, design & selection : PEDS》2009,22(1):19-26
Sulfolobus solfataricus protein disulphide oxidoreductase (SsPDO)contains three disulphide bridges linking residues C41XXC44,C155XXC158, C173XXXXC178. To get information on the role playedby these cross-links in determining the structural and functionalproperties of the protein, we performed site-directed mutagenesison Cys residues and investigated the changes in folding, stabilityand functional features of the mutants and analysed the resultswith computational analysis. The reductase activity of SsPDOand its mutants was evaluated by insulin and thioredoxin reductaseassays also coupled with peroxiredoxin Bcp1 of S. solfataricus.The three-dimensional model of SsPDO was constructed and correlatedwith circular dichroism data and functional results. Biochemicalanalysis indicated a key function for the redox site constitutedby Cys155 and Cys158. To discriminate between the role of thetwo cysteine residues, each cysteine was mutagenised and thebehaviour of the single mutants was investigated elucidatingthe basis of the electron-shuffling mechanism for SsPDO. Finally,cysteine pK values were calculated and the accessible surfacefor the cysteine side chains in the reduced form was measured,showing higher reactivity and solvent exposure for Cys155. 相似文献
72.
Teresa Ortega Elena De La Hera M. Emilia Carretero Pilar Gómez-Serranillos M. Victoria Naval Angel M. Villar Marin Prodanov Visitación Vacas Teresa Arroyo Teresa Hernández Isabel Estrella 《European Food Research and Technology》2008,227(6):1641-1650
Red wine has been reported to exert beneficial effects in preventing cardiovascular diseases probably due to their polyphenols
constituents. The vasorelaxant capacity and phenolic composition of four monovarietal young red wines Merlot, Tempranillo,
Garnacha and Cabernet-Sauvignon obtained from grapes from 2004 vintage, cultivated under the same climatic and agricultural
conditions, wine-making technology and storage conditions, were determined using vascular reactivity assay in rat aortic and
high-performance liquid chromatography, respectively. Primary cultures of vascular smooth muscle cells from Wistar rats were
also used to evaluate their survival prevention activity as well. Every studied wine present vasorelaxation effect, but the
higher value corresponds to the analyzed Merlot wine, especially rich in phenolic compounds, mainly catechins and oligomeric
proanthocyanidins and anthocyanin glycosides. This study further demonstrated previous investigations about the phenolic composition
of wines relation with their vasorelaxation activity. 相似文献
73.
Nuria Mateo Anson Robert Havenaar Wouter Vaes Leon Coulier Koen Venema Emilia Selinheimo Aalt Bast Guido R.M.M. Haenen 《Food chemistry》2011
The health benefits of whole grain consumption can be partly attributed to the inclusion of the bran or outer-layers of the grain rich in dietary fibre. Fibre is fermented in the colon, leading to the production of beneficial metabolites, such as short-chain fatty acids (SCFA). The effect of five different types of bread on the SCFA production was studied in an in vitro model of human colon. Additionally, the postprandial effects of two selected breads on the SCFA plasma concentrations were investigated in men. A higher in vitro production of butyrate was induced by wholemeal wheat bread with bioprocessed bran than by native bran. The increase in butyrate seemed to be in exchange for propionate, whilst the total SCFA production remained similar. However, differences between the two breads in the postprandial butyrate concentrations could not be detected in peripheral blood of men, probably due to an effective utilisation by colonocytes. 相似文献
74.
Emilia Ferrer Elisa Santoni Sauro Vittori Guillermina Font Jordi Mañes Gianni Sagratini 《Food chemistry》2011
A new analytical method, using pressurised liquid extraction (PLE) and liquid chromatography–tandem mass spectrometry (LC–MS/MS), was developed for the simultaneous determination of bisphenol A (BPA), octylphenol (OP) and nonylphenol (NP) in powdered infant formulas (IF) and powdered skimmed milk (PM). The analytes were extracted by PLE, using this optimised conditions: ethyl acetate as solvent, 70 °C of temperature, reversed-phase silica C18 as dispersing agent and three cycles of extraction. The extracts were then injected in LC–MS/MS using a Gemini C18 column and a mixture of 5% water and 95% methanol/acetonitrile, both with 0.1% ammonia, as a mobile phase. Recoveries at different fortification levels (0.5 and 0.05 mg kg−1), were between 89% and 92% for BPA, 84 and 98% for OP, and 93% and 101% for NP. The method was applied to the analysis of samples of PM and IF, bought in Italian and Spanish markets. In positive samples, phenols concentration ranged from 0.07 to 1.29 mg kg−1 for BPA, from 0.028 to 1.55 mg kg−1 for OP and from 0.026 to 1.47 mg kg−1 for NP. 相似文献
75.
M.Ahsanul Haque A.Bakar Sulong L.Kee Shyuan E.Herianto Majlan T. Husaini R.Emilia Rosli 《International Journal of Hydrogen Energy》2021,46(5):4339-4353
In this study, the polymer/MWCNT nanocomposites were synthesized from the pristine MWCNT and polymer binders using functionalization with solution processing methods. The synthesized polymer/MWCNT nanocomposites exhibited high specific surface areas than the pristine MWCNT. The MWCNT/Nafion nanocomposite attributed to the maximum peak current at 5.795 × 10?5 (A) while the peak current of MWCNT/PBI was obtained at 3.662 × 10?5 (A). Moreover, polymer/MWCNT based electrocatalysts performed better electrochemical activity because of polymers binders can assist electrochemical interaction using the high surface areas of the catalyst supporting material. Also, the MEAs fabricated using the hot pressing method, while the acid doped PBI membrane sandwiched between the electrodes. The fabricated MEAs were successfully demonstrated in a single cell and found capable of measuring a maximum power density of 112.10 mW/cm2 under 150 °C temperature. In conclusion, the synthesized catalyst-supporting materials enhanced the electrochemical activity and catalyst stability which fulfilling the main objective of this study. 相似文献
76.
Revilija Mozuraityte Inger Beate Standal Janna Cropotova Emilia Budźko Turid Rustad 《International Journal of Food Science & Technology》2021,56(4):1918-1928
Quality changes in Atlantic mackerel fillets during superchilled, chilled and frozen storage focusing on lipid quality, colour and changes in low molecular weight metabolites relevant for quality and safety were studied. Low formation of oxidation products was observed in chilled (up to 7 days), superchilled (up to 14 days) and frozen storage (up to one year). Only slight formation of TBARS was measured in the samples which correlated with the increasing fillet yellowness. The profile of low molecular weight compounds, analysed by high-resolution NMR, showed clear grouping of the different samples according to both treatment and storage time. The increase in K-value was highest in the chilled samples, reaching a K-value of 93 ± 3% on day 5, exceeding the proposed limit of human consumption (80%) while superchilling reached a K-value of ca 90 % after 14 days. Frozen samples showed acceptable quality in the whole storage period. 相似文献
77.
Emilia Janiszewska-Turak Paulina Bąk Andrzej Krzykowski Dorota Witrowa-Rajchert 《International Journal of Food Science & Technology》2021,56(6):2768-2779
The objective of this study was to determinate the influence of carrier addition and spray drying temperatures (160 or 200°C) on physicochemical properties of spray-dried carrot juice powder. As carriers, maltodextrin and gum Arabic in different proportions were used. In powders were determined the following: moisture content, water activity, apparent density, size of particles, colour and carotenoids content. The content of carotenoids in powders prepared from solutions with juice to carrier ratio 2:3 was 324.3–406.6 mg/kg d.m., while in powders with a J:C = 3:2 values ranged from 576.7 to 637.7 mg/kg d.m. The highest content of carotenoids and the most yellow colour were observed in powders with 1:3 gum Arabic to maltodextrin ratio. Powders with the highest amount of gum Arabic have the highest diameter and the lowest water activity. High inlet temperature caused brighter colour of powders, higher dry matter content, lower water activity and apparent density of powders. 相似文献
78.
79.
Laurà R Magnoli D Zichichi R Guerrera MC De Carlos F Suárez AÁ Abbate F Ciriaco E Vega JA Germanà A 《Microscopy research and technique》2012,75(3):359-366
The zebrafish pineal gland plays a fundamental role in the regulation of the circadian rhythm through the melatonin secretion. The pinealocytes, also called photoreceptive cells, are considered the morphofunctional unit of pineal gland. In literature, the anatomical features, the cellular characteristics, and the pinealocytes morphology of zebrafish pineal gland have not been previously described in detail. Therefore, this study was undertaken to analyze the structure and ultrastructure, as well as the immunohistochemical profile of the zebrafish pineal gland with particular reference to the pinealocytes. Here, we demonstrated, using RT-PCR, immunohistochemistry and transmission electron microscopy, the expression of the mRNA for rhodopsin in the pineal gland of zebrafish, as well as its cellular localization exclusively in the pinealocytes of adult zebrafish. Moreover, the ultrastructural observations demonstrated that the pinealocytes were constituted by an outer segment with numerous lamellar membranes, an inner segment with many mitochondria, and a basal pole with the synapses. Our results taken together demonstrated a central role of zebrafish pinealocytes in the control of pineal gland functions. 相似文献
80.
In this paper, we show that small artificial delays in the feedback loops operating in different time scales may stabilize singularly perturbed systems (SPSs). An artificial delay approach is proposed for the robust stabilization and L2‐gain analysis of SPSs in the finite frequency domain. A two‐time‐scale delayed static output feedback controller is designed, in which the controller gains are formulated via a linear matrix inequality (LMI) algorithm. A distinctive feature of the proposed algorithm is setting controller parameters as free variables, which increases the degrees of freedom in controller design and leads to more flexibility in solving LMIs. Moreover, the proposed method is further extended to analyze the finite frequency system specifications of SPSs. The L2‐gain performance analysis is conducted for parameter‐independent subsystems in their dominant frequency ranges, and the disturbance attenuation level of the original high‐order system is then estimated. Finally, the efficiency of the proposed design method is verified in an active suspension system subject to multiple finite frequency disturbance. 相似文献