全文获取类型
收费全文 | 2275篇 |
免费 | 42篇 |
国内免费 | 10篇 |
专业分类
电工技术 | 95篇 |
综合类 | 4篇 |
化学工业 | 409篇 |
金属工艺 | 75篇 |
机械仪表 | 69篇 |
建筑科学 | 45篇 |
能源动力 | 61篇 |
轻工业 | 125篇 |
水利工程 | 18篇 |
无线电 | 264篇 |
一般工业技术 | 432篇 |
冶金工业 | 535篇 |
原子能技术 | 84篇 |
自动化技术 | 111篇 |
出版年
2023年 | 7篇 |
2022年 | 17篇 |
2021年 | 27篇 |
2020年 | 18篇 |
2019年 | 25篇 |
2018年 | 39篇 |
2017年 | 31篇 |
2016年 | 47篇 |
2015年 | 31篇 |
2014年 | 43篇 |
2013年 | 91篇 |
2012年 | 83篇 |
2011年 | 128篇 |
2010年 | 82篇 |
2009年 | 92篇 |
2008年 | 91篇 |
2007年 | 100篇 |
2006年 | 64篇 |
2005年 | 57篇 |
2004年 | 52篇 |
2003年 | 56篇 |
2002年 | 59篇 |
2001年 | 45篇 |
2000年 | 39篇 |
1999年 | 53篇 |
1998年 | 209篇 |
1997年 | 142篇 |
1996年 | 89篇 |
1995年 | 54篇 |
1994年 | 50篇 |
1993年 | 57篇 |
1992年 | 21篇 |
1991年 | 36篇 |
1990年 | 12篇 |
1989年 | 23篇 |
1988年 | 21篇 |
1987年 | 14篇 |
1986年 | 16篇 |
1985年 | 26篇 |
1984年 | 25篇 |
1983年 | 18篇 |
1982年 | 24篇 |
1981年 | 17篇 |
1980年 | 15篇 |
1978年 | 13篇 |
1977年 | 7篇 |
1976年 | 20篇 |
1975年 | 7篇 |
1974年 | 6篇 |
1972年 | 6篇 |
排序方式: 共有2327条查询结果,搜索用时 0 毫秒
41.
We have demonstrated operation of a transmission system at the 3 ?m band. The system consists of a fluoride optical fibre, a superconducting BaPb1?xBixO3 (BPB) detector and a semiconductor Pb-salt diode laser. The low-level optical signal transmitted through the fibre is detected by the BPB detector up to 600 MHz. The observed results suggest that the BPB detector is suitable for use in infra-red optical transmission. 相似文献
42.
Keiichiro Sugimoto Sayaka Sakamoto Kazuya Nakagawa Shuichi Hayashi Naoki Harada Ryoichi Yamaji Yoshihisa Nakano Hiroshi Inui 《Food chemistry》2011
Eucalyptus leaf extract (ELE) is rich in hydrolyzable tannins. We examined the effects of ELE and its constituents on lipopolysaccharide (LPS)-induced liver injury in mice. Mice fed a diet supplemented with 1% ELE were intraperitoneally administered LPS. Six hours later, the serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) activities were significantly lower in the ELE-supplemented mice than in the controls; LPS-induced hepatic inducible nitric oxide synthase (iNOS) expression was also suppressed. ELE lowered LPS-stimulated iNOS expression in cultured RAW 264.7 macrophages. Furthermore, the aglycones of hydrolyzable tannins, gallic acid (GA) and ellagic acid (EA), inhibited iNOS induction to a greater extent than did ELE (15-fold higher). When mice were fed a 1% GA or EA diet, the increase in the serum ALT and AST activities and hepatic iNOS expression in response to the LPS challenge were significantly attenuated. Thus, hydrolyzable tannins in ELE ameliorate LPS-induced liver injury. 相似文献
43.
Shigeru Murakami 《Molecular nutrition & food research》2015,59(7):1353-1363
Taurine is a sulfur‐containing amino acid that is present in mammalian tissues in millimolar concentrations. Taurine is involved in a diverse array of biological and physiological functions, including bile salt conjugation, osmoregulation, membrane stabilization, calcium modulation, anti‐oxidation, and immunomodulation. The prevalence of obesity and being overweight continues to rise worldwide at an alarming rate. Obesity is associated with a higher risk of metabolic and cardiovascular diseases, cancer, and other clinical conditions. Ingestion of taurine has been shown to alleviate metabolic diseases such as hyperlipidemia, diabetes, hypertension, and obesity in animal models. A global epidemiological survey showed that 24‐h urinary taurine excretion, as a marker of dietary taurine intake, was inversely associated with BMI, blood pressure, and plasma cholesterol in humans. In addition, taurine chloramine, an endogenous product derived from activated neutrophils, has been reported to suppress obesity‐induced oxidative stress and inflammation in adipocytes. Synthetic activity and concentration of taurine in adipose tissues and plasma have been shown to decrease in humans and animals during the development of obesity, suggesting a relationship between taurine deficiency and obesity. In this review, I summarize the effects of taurine on the progression of obesity in animal models and humans. Furthermore, I discuss possible mechanisms underlying the antiobesity effects of taurine. 相似文献
44.
Maeda-Yamamoto M Saito T Nesumi A Tokuda Y Ema K Honma D Ogino A Monobe M Murakami A Murakami A Tachibana H 《Journal of the science of food and agriculture》2012,92(11):2379-2386
BACKGROUND: The purpose of this study was to evaluate the effects of leaf order or crop season on anthocyanins and other chemicals in the anthocyanin‐rich tea cultivar ‘Sunrouge’ (Camellia sinensis x C. taliensis) by using high‐performance liquid chromatography, and to study the effect of ‘Sunrouge’ extract on acetylcholinesterase (AChE) activity in human neuroblastoma SK‐N‐SH cells. RESULTS: The total anthocyanin content was higher in the third (3.09 mg g?1) than in the second (2.24 mg g?1) or first crop season (1.79 mg g?1). The amount of anthocyanins contained in the stem was high (1.61 mg g?1). In the third crop season, the concentrations of delphinidin‐3‐O‐β‐D ‐(6‐(E)‐p‐coumaroyl)galactopyranoside (DCGa), cyanidin‐3‐O‐β‐D ‐(6‐(E)‐p‐coumaroyl)galactopyranoside, delphinidin‐3‐O‐β‐D ‐galactopyranoside, delphinidin‐3‐O‐β‐D ‐(6‐O‐(Z)‐p‐coumaroyl)galactopyranoside, cyanidin‐3‐O‐β‐D ‐galactoside, and delphinidin‐3‐O‐β‐D ‐glucoside were 1.57 mg g?1, 0.52 mg g?1, 0.40 mg g?1, 0.22 mg g?1, 0.14 mg g?1, and 0.11 mg g?1, respectively. DCGa accounted for about 50% of the anthocyanins present. The suppressive effect of ‘Sunrouge’ water extract on AChE activity in human neuroblastoma SK‐N‐SH cells was the strongest among the three tea cultivars (‘Sunrouge’, ‘Yabukita’ and ‘Benifuuki’). CONCLUSION: These results suggested that ‘Sunrouge’ might protect humans from humans from AChE‐related diseases by suppressing AChE activity. To obtain sufficient amounts of anthocyanins, catechins and/or caffeine for a functional food material, ‘Sunrouge’ from the third crop season should be used. Copyright © 2012 Society of Chemical Industry 相似文献
45.
46.
Kalidas Shetty Masahiro Ohshima Taka Murakami Katsuji Oosawa Yuko Ohashi 《Food Biotechnology》2013,27(2):111-128
Abstract Melon (Cucumis melo L.) is an important fruit crop cultivated widely in every region of the world. Our laboratory is targeting this species for production of novel proteins important to food industry. Prior to expression of protein of interest in transgenic melon an efficient genetic transformation system has to be developed. In this context we are testing a wide variety of promoters fused to reporter gene for β‐glucuronidase (GUS) for expression specifically in melon fruits. In this study in melon, salicylic acid‐inducible promoter region of pathogenesis‐related protein gene (PR1a) of tobacco fused to β‐glucuronidase (GUS) gene was introduced into melon via Agrobacterium‐mediated gene transfer using a binary vector system. Gene transfer was effective when Agrobacterium virulence factors like acetosyringone (100 μM) and low pH (5.2) were provided during the co‐culture step. Transformed shoots were recovered from benzyladenine‐induced cut cotyledons using kanamycin gene as a selective marker. Regeneration of shoots from cotyledons was stimulated by providing 10 mM proline in the shoot organogenesis medium. Southern and Northern blot analysis of transformants confirmed the presence of β‐glucuronidase gene in two selected clones J‐3 and PR‐G. The transformants also showed high β‐glucuronidase activity after salicylic acid treatment. Thiamine, a previously known inducer of pathogenesis‐related protein, stimulated β‐glucuronidase in J‐3 but not PR‐G melon transformants tested in this study. These studies showed that tobacco PR1a promoter region can be expressed in melon and it was stimulated by salicylic acid. This indicates the potential to use the promoter region of tobacco PR1a for genetic improvement of melon for specific food processing‐related characteristics or for expression of novel food‐related proteins. The promoter region could be used to drive specific target genes under stress or salicylic acid induced conditions. 相似文献
47.
48.
Karina Cardoso Tramonte João Gustavo Provesi Iolanda Moreira Dutra Albuquerque E Silva Aureanna Nairne Negrão Murakami Marcelo Maraschin Renata Dias De Mello Castanho Amboni Edna Regina Amante 《International Journal of Food Science & Technology》2011,46(9):1871-1877
The heart of palm is a food extracted from several species of palm trees. Only 10–20% of the raw material is transformed into canned hearts of palm, therefore this agro‐industry generates a large quantity of solid residue. The aim of this work was to extract and characterise a juice produced from this solid residue. This extract is compared with the traditional fruit juices (orange and pineapple juices), obtaining higher contents of minerals, such as magnesium (22.80 mg/100 g) and potassium (276.90 mg/100 g), phenolic compounds (gallic, 3,4‐dihydroxybenzoic, chlorogenic, syringic and caffeic acids) and high free radical scavenging capacity (expressed as 2,2‐diphenyl‐1‐picrylhydrazyl), which suggest high antioxidant activity. Additionally, a new soft drink was formulated using this king palm juice as its main ingredient. The soft drink samples formulated with this juice had high sensory acceptability and high intention of consumption, which suggests an important and low‐cost application for this industrial residue. 相似文献
49.
Dispersion in the Presence of Acetic Acid or Ammonia Confers Gliadin‐Like Characteristics to the Glutenin in Wheat Gluten 下载免费PDF全文
Spray‐dried gluten has unique properties and is commercially available in the food industry worldwide. In this study, we examined the viscoelastic properties of gluten powder prepared by dispersion in the presence of acetic acid or an ammonia solvent and then followed by lyophilization instead of a spray drying. Mixograph measurements showed that the acid‐ and ammonia‐treated gluten powders had marked decreases in the time to peak dough resistance when compared with the control gluten powder. The integrals of the dough resistance and bandwidth for 3 min after peak dough resistance decreased in both treated gluten powders. Similar phenomena were observed when gliadin was supplemented to gluten powders. Basic and acidic conditions were applied to the acid‐ and ammonia‐treated gluten powders, respectively, and the viscoelastic behaviors were found to depend on the pH in the gluten dispersion just before lyophilization. These behaviors suggest that gluten may assume a reversible change in viscoelasticity by a fluctuation in pH during gluten dispersion. SDS‐PAGE showed that the extractable proteins substantially increased in some polymeric glutenins including the low molecular weight‐glutenin subunit (LMW‐GS) when the ammonia‐treated gluten powder was extracted with 70% ethanol. In contrast, the extractable proteins markedly increased in many polymeric glutenins including the high molecular weight‐glutenin subunit and/or the LMW‐GS when the acid‐treated gluten powder was extracted with 70% ethanol. It thus follows that the extractability of polymeric glutenin to ethanol increases similarly to gliadin when gluten is exposed to an acidic or a basic pH condition; therefore, glutenin adopts gliadin‐like characteristics. 相似文献
50.