全文获取类型
收费全文 | 1667篇 |
免费 | 100篇 |
国内免费 | 3篇 |
专业分类
电工技术 | 17篇 |
综合类 | 9篇 |
化学工业 | 558篇 |
金属工艺 | 35篇 |
机械仪表 | 30篇 |
建筑科学 | 68篇 |
矿业工程 | 2篇 |
能源动力 | 46篇 |
轻工业 | 128篇 |
水利工程 | 31篇 |
石油天然气 | 2篇 |
无线电 | 99篇 |
一般工业技术 | 310篇 |
冶金工业 | 188篇 |
原子能技术 | 6篇 |
自动化技术 | 241篇 |
出版年
2023年 | 18篇 |
2022年 | 45篇 |
2021年 | 44篇 |
2020年 | 36篇 |
2019年 | 56篇 |
2018年 | 48篇 |
2017年 | 47篇 |
2016年 | 50篇 |
2015年 | 40篇 |
2014年 | 76篇 |
2013年 | 97篇 |
2012年 | 76篇 |
2011年 | 119篇 |
2010年 | 81篇 |
2009年 | 64篇 |
2008年 | 76篇 |
2007年 | 72篇 |
2006年 | 64篇 |
2005年 | 59篇 |
2004年 | 41篇 |
2003年 | 48篇 |
2002年 | 27篇 |
2001年 | 26篇 |
2000年 | 15篇 |
1999年 | 22篇 |
1998年 | 42篇 |
1997年 | 30篇 |
1996年 | 23篇 |
1995年 | 26篇 |
1994年 | 16篇 |
1993年 | 22篇 |
1992年 | 14篇 |
1991年 | 10篇 |
1990年 | 16篇 |
1989年 | 11篇 |
1988年 | 7篇 |
1987年 | 7篇 |
1986年 | 17篇 |
1985年 | 11篇 |
1984年 | 12篇 |
1983年 | 15篇 |
1982年 | 11篇 |
1981年 | 16篇 |
1980年 | 10篇 |
1979年 | 16篇 |
1978年 | 10篇 |
1977年 | 15篇 |
1976年 | 11篇 |
1975年 | 10篇 |
1973年 | 7篇 |
排序方式: 共有1770条查询结果,搜索用时 15 毫秒
61.
Due to the recognized toxicity of acrylamide, intensive efforts have been made to reduce the concentration of this undesired Maillard by-product in food. This work reports the results obtained from a series of experiments aimed at determining the concentration of acrylamide and the in vitro radical scavenging capacity in the same roasted and ground coffee samples, as it is well established that a significant part of the antioxidant activity in coffee is linked to the melanoidins, which are also considered as Maillard reaction products (MRPs). The radical scavenging capacity was measured using electroparamagnetic resonance (EPR). Coffee samples from the Robusta and Arabica varieties were roasted at 236 °C over different time periods to obtain very light, light, medium and dark roast. Color analyses were performed on all samples. Increasing the roasting degree led to a decrease in acrylamide concentration as well as radical scavenging capacity. The results of this work indicate that any mitigation efforts must also take into account the potential loss of desired food constituents and consequently changes to the risk/benefit characteristics of foods. 相似文献
62.
Daniel Cozzolino Marcel Labandera 《Journal of the science of food and agriculture》2002,82(4):380-384
Near‐infrared reflectance spectroscopy (NIRS) was used to predict the dry matter (DM) and crude protein (CP) contents of untreated forage samples. Four hundred forage samples were analysed in reflectance mode. Two mathematical treatments based on the order of derivative of log(1/R), the gap in data points and the numbers of data points used in the first and second smoothings were applied. Predictive equations were developed using modified partial least squares (MPLS) with internal cross‐validation. The coefficient of determination of calibration and the standard error of cross‐validation (SECV, in parentheses) for DM were 0.92 (12.4), 0.92 (12.6) and 0.93 (11.7) for the two treatments and log(1/R) respectively on a g kg?1 fresh weight basis. For CP the NIRS calibration statistics yielded and SECV (in parentheses) values of 0.85 (19.8), 0.85 (19.5) and 0.87 (18.1) for the two treatments and log(1/R) respectively on a g kg?1 fresh weight basis. It was concluded that NIRS is a suitable method to predict the dry matter and crude protein contents of fresh forage without sample preparation. © 2002 Society of Chemical Industry 相似文献
63.
Arnau Vidal Marcel Mengelers Shupeng Yang Sarah De Saeger Marthe De Boevre 《Comprehensive Reviews in Food Science and Food Safety》2018,17(5):1127-1155
To date, the use of biomarkers has become generally accepted. Biomarker‐driven research has been proposed as a successful method to assess the exposure to xenobiotics by using concentrations of the parent compounds and/or metabolites in biological matrices such as urine or blood. However, the identification and validation of biomarkers of exposure remain a challenge. Recent advances in high‐resolution mass spectrometry along with new analytical (post‐acquisition data‐mining) techniques will improve the quality and output of the biomarker identification process. Chronic or even acute exposure to mycotoxins remains a daily fact, and therefore it is crucial that the mycotoxins’ metabolism is unravelled so more knowledge on biomarkers in humans and animals is acquired. This review aims to provide the scientific community with a comprehensive overview of reported in vitro and in vivo mycotoxin metabolism studies in relation to biomarkers of exposure for deoxynivalenol, nivalenol, fusarenon‐X, T‐2 toxin, diacetoxyscirpenol, ochratoxin A, citrinin, fumonisins, zearalenone, aflatoxins, and sterigmatocystin. 相似文献
64.
Solar radiation is a key factor determining electricity produced by photovoltaic (PV) systems. This paper presents a solar radiation database of Europe developed in the geographical information system, and three interactive web applications providing an access to it. The database includes monthly and yearly average values of the global irradiation on horizontal and inclined surfaces, as well as climatic parameters needed for an assessment of the potential PV electricity generation (Linke atmospheric turbidity, the ratio of diffuse to global irradiation, an optimum inclination angle of modules to maximize energy yield). In the first web application, a user may browse radiation maps and query irradiation incident on a PV module for different inclination angles. The second application simulates daily profiles of irradiance for a chosen month and module inclination and orientation. The third web application estimates electricity generation for a chosen PV configuration. It also calculates optimal inclination and orientation of a PV module for a given location. The database and the applications are accessible at http://re.jrc.cec.ev.int/pvgis/pv/imaps/imaps.htm. 相似文献
65.
Cristina Flox Javier Rubio-Garcia Raquel Nafria Reza Zamani Marcel Skoumal Teresa Andreu Jordi Arbiol Andreu Cabot Joan Ramon Morante 《Carbon》2012,50(6):2372-2374
Graphene-supported monometallic (Pt) and bimetallic (CuPt3) cubic nanocatalysts have been investigated as new positive electrode materials for improving the VO2+/VO2+ redox process occurring in the vanadium redox flow batteries (VRB). High-resolution transmission electron microscopy (HRTEM) and scanning electron microscopy (SEM) have been employed to characterize the electrodes. The presence of the CuPt3 nanocubes on graphene conferred higher electrocatalytic activity due to the much higher electroactive area compared to that obtained with the Pt nanoparticles. The electrochemical surface area of the nano-(CuPt3)-decorated graphene electrode was 105% higher compared to non-decorated graphene, being then a promising alternative for improving the VRB. 相似文献
66.
Esther Hontañón Marcel Rouenhoff Alfredo Azabal Emilio Ramiro Frank Einar Kruis 《Aerosol science and technology》2014,48(3):333-339
An existing differential mobility analyzer (DMA) of cylindrical electrodes and a novel DMA of rectangular plate electrodes are demonstrated for size fractionation of nanoparticles at high-aerosol flow rates in this work. The two DMAs are capable of delivering monodisperse size selected nanoparticles (SMPS σg < 1.1) at gas flow rates ranging from 200 slm to 500 slm. At an aerosol flow rate of 200 slm, the maximum attainable particle mean size is of about 20 nm for the cylindrical DMA and of nearly 50 nm for the rectangular plate DMA. The number concentration of the monodisperse nanoparticles delivered by the high-flow DMAs spans from 104 cm?3 to 106 cm?3 depending upon the particle mean size and particle size dispersion.
Copyright 2014 American Association for Aerosol Research 相似文献
67.
For measurement outside the laboratory, uncertainty evaluations have to be model-based. Therefore models should not only represent the measurand but also its environment. For measurement in social science these models will be too complex, therefore instead of white-box models, grey-box (modular-designed) models are preferred. They are much simpler. Uncertainty evaluations of measurements outside the laboratory are more of the kind of Type B evaluations. In social science, due to the lack of authoritative scientific institutions, Type B evaluations will be of a different character. In case of measurements based on grey-box models they are the so-called structure-oriented behaviour tests. 相似文献
68.
The presence of saliva in the oral environment is relevant for several essential health processes. However, the noncontrolled early saliva interaction with biomaterials manufactured for oral rehabilitation may generate alterations in the superficial properties causing negative biological outcomes. Therefore, the present review aimed to provide a compilation of all possible physical–chemical–biological changes caused by the early saliva interaction in dental implants and materials for oral regeneration. Dental implants, bone substitutes and membranes in dentistry possess different properties focused on improving the healing process when in contact with oral tissues. The early saliva interaction was shown to impair some positive features present in biomaterials related to quick cellular adhesion and proliferation, such as surface hydrophilicity, cellular viability and antibacterial properties. Moreover, biomaterials that interacted with contaminated saliva containing specific bacteria demonstrated favorable conditions for increased bacterial metabolism. Additionally, the quantity of investigations associating biomaterials with early saliva interaction is still scarce in the current literature and requires clarification to prevent clinical failures. Therefore, clinically, controlling saliva exposure to sites involving the application of biomaterials must be prioritized in order to reduce impairment in important biomaterial properties developed for rapid healing. 相似文献
69.
Daniela Grimm Herbert Schulz Marcus Krüger Jos Luis Corts-Snchez Marcel Egli Armin Kraus Jayashree Sahana Thomas J. Corydon Ruth Hemmersbach Petra M. Wise Manfred Infanger Markus Wehland 《International journal of molecular sciences》2022,23(6)
Cancer is a disease exhibiting uncontrollable cell growth and spreading to other parts of the organism. It is a heavy, worldwide burden for mankind with high morbidity and mortality. Therefore, groundbreaking research and innovations are necessary. Research in space under microgravity (µg) conditions is a novel approach with the potential to fight cancer and develop future cancer therapies. Space travel is accompanied by adverse effects on our health, and there is a need to counteract these health problems. On the cellular level, studies have shown that real (r-) and simulated (s-) µg impact survival, apoptosis, proliferation, migration, and adhesion as well as the cytoskeleton, the extracellular matrix, focal adhesion, and growth factors in cancer cells. Moreover, the µg-environment induces in vitro 3D tumor models (multicellular spheroids and organoids) with a high potential for preclinical drug targeting, cancer drug development, and studying the processes of cancer progression and metastasis on a molecular level. This review focuses on the effects of r- and s-µg on different types of cells deriving from thyroid, breast, lung, skin, and prostate cancer, as well as tumors of the gastrointestinal tract. In addition, we summarize the current knowledge of the impact of µg on cancerous stem cells. The information demonstrates that µg has become an important new technology for increasing current knowledge of cancer biology. 相似文献
70.
Social impacts and degrees of organization inherent to opinion formation for interacting agents on networks present interesting
questions of general interest from physics to sociology. We present a quantitative analysis of a case implying an evolving
small size network, i.e. that inherent to the ongoing debate between modern creationists (most are Intelligent Design (ID)
proponents (IDP) and Darwin’s theory of Evolution Defenders (DED)). This study is carried out by analyzing the structural
properties of the citation network unfolded in the recent decades by publishing works belonging to members of the two communities.
With the aim of capturing the dynamical aspects of the interaction between the IDP and DED groups, we focus on two key quantities,
namely, the degree of activity of each group and the corresponding degree of impact on the intellectual community at large.
A representative measure of the former is provided by the rate of production of publications (RPP), whilst the latter can
be assimilated to the rate of increase in citations (RIC). These quantities are determined, respectively, by the slope of
the time series obtained for the number of publications accumulated per year and by the slope of a similar time series obtained
for the corresponding citations. The results indicate that in this case, the dynamics can be seen as geared by triggered or
damped competition. The network is a specific example of marked heterogeneity in exchange of information activity in and between
the communities, particularly demonstrated through the nodes having a high connectivity degree, i.e. opinion leaders. 相似文献