全文获取类型
收费全文 | 15843篇 |
免费 | 1612篇 |
国内免费 | 567篇 |
专业分类
电工技术 | 523篇 |
技术理论 | 2篇 |
综合类 | 1145篇 |
化学工业 | 3950篇 |
金属工艺 | 590篇 |
机械仪表 | 728篇 |
建筑科学 | 1011篇 |
矿业工程 | 468篇 |
能源动力 | 288篇 |
轻工业 | 4498篇 |
水利工程 | 160篇 |
石油天然气 | 568篇 |
武器工业 | 83篇 |
无线电 | 604篇 |
一般工业技术 | 1420篇 |
冶金工业 | 697篇 |
原子能技术 | 406篇 |
自动化技术 | 881篇 |
出版年
2024年 | 73篇 |
2023年 | 318篇 |
2022年 | 465篇 |
2021年 | 750篇 |
2020年 | 732篇 |
2019年 | 567篇 |
2018年 | 580篇 |
2017年 | 608篇 |
2016年 | 619篇 |
2015年 | 632篇 |
2014年 | 973篇 |
2013年 | 1240篇 |
2012年 | 1137篇 |
2011年 | 1108篇 |
2010年 | 883篇 |
2009年 | 832篇 |
2008年 | 705篇 |
2007年 | 852篇 |
2006年 | 817篇 |
2005年 | 688篇 |
2004年 | 567篇 |
2003年 | 532篇 |
2002年 | 452篇 |
2001年 | 353篇 |
2000年 | 262篇 |
1999年 | 225篇 |
1998年 | 176篇 |
1997年 | 170篇 |
1996年 | 112篇 |
1995年 | 105篇 |
1994年 | 85篇 |
1993年 | 59篇 |
1992年 | 66篇 |
1991年 | 29篇 |
1990年 | 29篇 |
1989年 | 27篇 |
1988年 | 19篇 |
1987年 | 27篇 |
1986年 | 26篇 |
1985年 | 34篇 |
1984年 | 23篇 |
1983年 | 10篇 |
1982年 | 19篇 |
1981年 | 7篇 |
1980年 | 10篇 |
1979年 | 3篇 |
1978年 | 2篇 |
1959年 | 2篇 |
1958年 | 2篇 |
1951年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 203 毫秒
71.
Front-of-package labels (FOPL) are recommended to reduce consumer intake of ultra-processed food products (UPP). The multiple traffic-light label is one example of FOPL that indicates the content of target nutrients in products by displaying red (high), amber (medium), and/or green (low) color-coding. The red code may implicitly enhance sweetness perception and approach dispositions toward sweet UPP via cross-modal visual-taste interactions. We conducted two experiments to examine the possibility of contradictory influence of explicitly learned and implicit cross-modal associations on the emotional responses evoked by UPP pictures. In both experiments, we first explicitly associated the color codes with health-related meanings. In Experiment I (n = 78), a psychometric tool estimated the emotional responses (pleasantness and arousal ratings) evoked by UPP pictures when preceded by red, amber, or green color-codes. In Experiment II (n = 24), we recorded participants’ electrocortical brain activity to assess the early posterior negativity (EPN) component as an index of the emotional responses to UPP. The reported pleasantness (Experiment I) and the EPN amplitude (Experiment II) were greater for sweet UPP relative to salty UPP when primed with red codes but not when primed with green or amber. A red code increased positive emotions toward sweet UPP despite its explicit association with increased health-risks. Thus, the use of multiple traffic-lights might lead to an unintended implicit approach behavior toward sweet UPP. Designers, researchers, and policy makers may consider color-taste cross-modal associations when designing, testing, and applying FOPL. 相似文献
72.
Rieke Himstedt Dr. Silke Wagner Dr. Robert J. R. Jaeger Dr. Michèle-Laure Lieunang Watat Dr. Jana Backenköhler Dr. Zeljka Rupcic Prof. Dr. Marc Stadler Prof. Dr. Peter Spiteller 《Chembiochem : a European journal of chemical biology》2020,21(11):1613-1620
Mycenarubin C, a previously unknown red pyrroloquinoline alkaloid, was isolated from fruiting bodies of the mushroom Mycena rosea and its structure was elucidated mainly by NMR spectroscopy and mass spectrometry. Unlike mycenarubin A, the major pyrroloquinoline alkaloid in fruiting bodies of M. rosea, mycenarubin C, contains an eight-membered ring with an additional C1 unit that is hitherto unprecedented for pyrroloquinoline alkaloids known in nature. Incubation of mycenarubin A with an excess of formaldehyde revealed that mycenarubin C was generated nearly quantitatively from mycenarubin A. An investigation into the formaldehyde content of fresh fruiting bodies of M. rosea showed the presence of considerable amounts of formaldehyde, with values of 5 μg per gram of fresh weight in fresh fruiting bodies. Although mycenarubin C did not show bioactivity against selected bacteria and fungi, formaldehyde inhibits the growth of the mycoparasite Spinellus fusiger at concentrations present in fruiting bodies of M. rosea. Therefore, formaldehyde might play an ecological role in the chemical defence of M. rosea against S. fusiger. In turn, S. fusiger produces gallic acid—presumably to detoxify formaldehyde by reaction of this aldehyde with amino acids and gallic acid to Mannich adducts. 相似文献
73.
Zviadi Mestvirishvili Vakhtang Kvatchadze Irakli Bairamashvili Nikoloz Jalabadze Tornike Mestvirishvili 《Materials Science & Technology》2020,36(3):327-333
ABSTRACTA method of ultrafine macro-homogeneous composite powder – B4C–ZrO2 production using a planetary mill was developed. From the macro-homogeneous composite high-density ceramics, B4C–ZrB2 was produced by the method of reactive sintering (in situ) at 2000°C under the pressure of 41–42?MPa. The effect of ZrO2 grain size and of its distribution in the matrix on the consolidation parameters, and the microstructure of the obtained ceramics was studied. 相似文献
74.
75.
探析如何让京津冀地区独特的校园文化衍生品得到创新性发展,让文创产品更容易达到共情的目的,并传递不同的校园文化价值,围绕校园文化衍生品进行创新性设计。基于对京津冀地区不同校园文化背景的调研,在文旅融合背景下分析校园文化产品的现状与发展,以及有代表性的校园文化品牌。以清华大学文创产品为例,设计出具有创新性的校园文化产品,将文化元素与产品设计相结合。运用校园特色建筑、色彩、文化背景,发挥其原创性、传播性、文化性等优势,传播学校的理念及文化,扩大校园文化传播途径。在文旅融合背景下,设计出独特的校园文化衍生产品,传承文化内涵与理念,并提高校园文化认同感与归属感,成为京津冀地区发展校园文化的趋势,从而推动文化旅游产业的发展。 相似文献
76.
Bram H. Frohock Jessica M. Gilbertie Dr. Jennifer C. Daiker Dr. Lauren V. Schnabel Dr. Joshua G. Pierce 《Chembiochem : a European journal of chemical biology》2020,21(7):933-937
The failure of frontline antibiotics in the clinic is one of the most serious threats to human health and requires a multitude of novel therapeutics and innovative approaches to treatment so as to curtail the growing crisis. In addition to traditional resistance mechanisms resulting in the lack of efficacy of many antibiotics, most chronic and recurring infections are further made tolerant to antibiotic action by the presence of biofilms. Herein, we report an expanded set of 5-benzylidene-4-oxazolidinones that are able to inhibit the formation of Staphylococcus aureus biofilms, disperse preformed biofilms, and, in combination with common antibiotics, are able to significantly reduce the bacterial load in a robust collagen-matrix model of biofilm infection. 相似文献
77.
Qiaozhi Zhang Yanbo Wang Linglin Fu 《Comprehensive Reviews in Food Science and Food Safety》2020,19(5):2559-2587
Dietary advanced glycation end products (dAGEs) are complex and heterogeneous compounds derived from nonenzymatic glycation reactions during industrial processing and home cooking. There is mounting evidence showing that dAGEs are closely associated with various chronic diseases, where the absorbed dAGEs fuel the biological AGEs pool to exhibit noxious effects on human health. Currently, due to the uncertain bioavailability and rapid renal clearance of dAGEs, the relationship between dAGEs and biological AGEs remains debatable. In this review, we provide the most updated information on dAGEs including their generation in processed foods, analytical and characterization techniques, metabolic fates, interaction with AGE receptors, implications on human health and reducing strategies. Available evidence demonstrating a relevance between dAGEs and food allergy is also included. AGEs are ubiquitous in foods and their contents largely depend on the reactivity of carbonyl and amino groups, along with surrounding condition mainly pH and heating procedures. Once being digested and absorbed into the circulation, two separate pathways can be involved in the deleterious effects of dAGEs: an AGE receptor‐dependent way to stimulate cell signals, and an AGE receptor‐independent way to dysregulate proteins via forming complexes. Inhibition of AGEs formation during food processing and reduction in the diet are two potent approaches to restrict health‐hazardous dAGEs. To elucidate the biological role of dAGEs toward human health, the following significant perspectives are raised: molecular size and complexity of dAGEs; interactions between unabsorbed dAGEs and gut microbiota; and roles played by concomitant compounds in the heat‐processed foods. 相似文献
78.
Our study provides first empirical evidence on young Russian consumers’ attitudes towards novel functional bakery products. We employ two different bakery products, namely bread rolls and biscuits, in our experimental auctions. Both products are derived from purple wheat, an old wheat variety that is naturally rich in anthocyanins (ACNs). ACNs are assumed to possess anti-inflammatory, anti-cancer, anti-diabetic and ocular-health-enhancing properties. Participants are 207 students aged 18–30 years from Moscow and Irkutsk. Our results indicate a low level of knowledge about ACNs among participants. However, our results also show that in the presence of information about the health-enhancing characteristics most participants value these products over base products. Our findings also reinforce the idea that the base product matters. Purple wheat bread rolls were better accepted than purple wheat biscuits. Moreover, our results also highlight that the information strategy matters. Participants in our study exhibited a higher willingness to pay for purple wheat biscuits under an old variety information scenario in comparison to an anthocyanin information scenario. Moreover, while our results indicate no significant difference in the perception of the anthocyanin attribute between the two cities, the perception of old grain variety products was slightly different. The share of respondents considering old variety products as healthy was significantly higher in Irkutsk, whereas the share of respondents considering these products as exclusive was significantly higher in Moscow. Thus, while planning future marketing strategies such differences in underlying motives should be taken into account. 相似文献
79.
Foodborne illnesses are syndromes including nausea, vomiting, abdominal cramps and diarrhea caused by the ingestion of food contaminated by chemical substances or microorganisms and/or their toxins. Reporting of food poisoning has been mandatory for European Union member states since 2003. Data collected by the European Food Safety Authority (EFSA) include number of outbreaks per causative agent, number of human cases as well as hospitalization and death rates. This paper will focus on meat products as food vehicles for FBOs. Following the legal definition of meat and meat products and the European reporting scheme, the main pathogenic bacteria will be presented. 相似文献
80.
食物成瘾的研究进展及启示 总被引:2,自引:0,他引:2
食物成瘾是一种复杂的慢性疾病,导致人们在日常生活中对某种食物产生过度依赖与过度进食等相关行为特征,近年来已被认为是影响欧美发达国家肥胖症、暴食症、糖尿病等发病率持续升高的关键原因,引起学术界的极大关注,成为研究热点。本文主要介绍食物成瘾的概念、诊断标准,综述了食物成瘾的病理机制、影响因素和应对措施等方面的研究进展,并探讨食物成瘾对我国食品界的启示,为预防食物成瘾,保障公众健康提供有益借鉴。 相似文献