全文获取类型
收费全文 | 60506篇 |
免费 | 6192篇 |
国内免费 | 3062篇 |
专业分类
电工技术 | 4433篇 |
技术理论 | 9篇 |
综合类 | 6323篇 |
化学工业 | 3604篇 |
金属工艺 | 939篇 |
机械仪表 | 2724篇 |
建筑科学 | 8836篇 |
矿业工程 | 4043篇 |
能源动力 | 1784篇 |
轻工业 | 7487篇 |
水利工程 | 4121篇 |
石油天然气 | 5244篇 |
武器工业 | 1159篇 |
无线电 | 3112篇 |
一般工业技术 | 4368篇 |
冶金工业 | 1827篇 |
原子能技术 | 1214篇 |
自动化技术 | 8533篇 |
出版年
2024年 | 153篇 |
2023年 | 848篇 |
2022年 | 1765篇 |
2021年 | 2191篇 |
2020年 | 2230篇 |
2019年 | 1699篇 |
2018年 | 1705篇 |
2017年 | 1890篇 |
2016年 | 2376篇 |
2015年 | 2457篇 |
2014年 | 4767篇 |
2013年 | 3953篇 |
2012年 | 5259篇 |
2011年 | 5051篇 |
2010年 | 3750篇 |
2009年 | 3709篇 |
2008年 | 3406篇 |
2007年 | 4064篇 |
2006年 | 3561篇 |
2005年 | 2986篇 |
2004年 | 2349篇 |
2003年 | 2040篇 |
2002年 | 1476篇 |
2001年 | 1223篇 |
2000年 | 934篇 |
1999年 | 758篇 |
1998年 | 544篇 |
1997年 | 515篇 |
1996年 | 391篇 |
1995年 | 343篇 |
1994年 | 271篇 |
1993年 | 225篇 |
1992年 | 138篇 |
1991年 | 125篇 |
1990年 | 84篇 |
1989年 | 104篇 |
1988年 | 62篇 |
1987年 | 38篇 |
1986年 | 36篇 |
1985年 | 36篇 |
1984年 | 37篇 |
1983年 | 38篇 |
1982年 | 18篇 |
1981年 | 14篇 |
1979年 | 13篇 |
1978年 | 11篇 |
1977年 | 9篇 |
1963年 | 7篇 |
1959年 | 13篇 |
1956年 | 7篇 |
排序方式: 共有10000条查询结果,搜索用时 203 毫秒
1.
2.
Yujie Chen Yiping Song Zhen Zhang Yali Chen Qiliang Deng Shuo Wang 《Advanced functional materials》2021,31(41):2104885
Various products, including foods and pharmaceuticals, are sensitive to temperature fluctuations. Thus, temperature monitoring during production, transportation, and storage is critical. Facile indicators are required to monitor temperature conditions via color changes in real time. This study aimed to prepare and apply thiol-functionalized covalent organic frameworks (COFs) as a novel indicator for monitoring thermal history and temperature abuse. The COFs underwent obvious color changes from bright yellow to purple after exposure to different temperatures for varying durations. The reaction kinetics are analyzed under isothermal conditions, which reveal that the order of reaction rates is k−20°C < k4°C < k20°C < k35°C < k55°C. The activation energy (Ea) of the COFs is calculated using the Arrhenius equation as 50.71 kJ moL−1. The COFs are capable of sensitive color changes and offer a broad temperature tracking range, thereby demonstrating their application potential for the monitoring of temperature and time exposure history during production, transportation, and storage. This excellent performance thermal history indicator also shows promise for expanding the application field of COFs. 相似文献
3.
Giorgio Valabrega Giulia Scotto Valentina Tuninetti Arianna Pani Francesco Scaglione 《International journal of molecular sciences》2021,22(8)
Poly(ADP-ribose) polymerases (PARP) are proteins responsible for DNA damage detection and signal transduction. PARP inhibitors (PARPi) are able to interact with the binding site for PARP cofactor (NAD+) and trapping PARP on the DNA. In this way, they inhibit single-strand DNA damage repair. These drugs have been approved in recent years for the treatment of ovarian cancer. Although they share some similarities, from the point of view of the chemical structure and pharmacodynamic, pharmacokinetic properties, these drugs also have some substantial differences. These differences may underlie the different safety profiles and activity of PARPi. 相似文献
4.
Karolina Storesund Francine Amon Anne Steen‐Hansen Shayesteh Haghighatpanah Ida Larsson 《火与材料》2021,45(1):181-190
The aim of this exploratory study has been to investigate the fire properties and environmental aspects of different upholstery material combinations, mainly for domestic applications. An analysis of the sustainability and circularity of selected textiles, along with lifecycle assessment, is used to qualitatively evaluate materials from an environmental perspective. The cone calorimeter was the primary tool used to screen 20 different material combinations from a fire performance perspective. It was found that textile covers of conventional fibres such as wool, cotton and polyester, can be improved by blending them with fire resistant speciality fibres. A new three‐dimensional web structure has been examined as an alternative padding material, showing preliminary promising fire properties with regard to ignition time, heat release rates and smoke production. 相似文献
5.
6.
分析近年来RTO装置发生的安全事故,找出了该类环保装置存在的安全风险,并在储罐与污水池废气分类处理、在线废气浓度检测仪与废气切断阀的位置设置、新风稀释及风机控制、阻火器与爆破片、操作压力、储罐呼吸阀后采用非接触废气罩收集、风机材质等方面提出了建议。 相似文献
7.
Oblivious polynomial evaluation (OPE) is a two-party protocol that allows a receiver, R to learn an evaluation f(α), of a sender, S's polynomial f(x), whilst keeping both α and f(x) private. This protocol has attracted a lot of attention recently, as it has wide ranging applications in the field of cryptography.
In this article we review some of these applications and, additionally, take an in-depth look at the special case of information theoretic OPE. Specifically, we provide a current and critical review of the existing information theoretic OPE protocols in the literature. We divide these protocols into two distinct cases (three-party and distributed OPE) allowing for the easy distinction and classification of future information theoretic OPE protocols. In addition to this work, we also develop several modifications and extensions to existing schemes, resulting in increased security, flexibility and efficiency. Lastly, we also identify a security flaw in a previously published OPE scheme. 相似文献
8.
为缓解我国水、能源和粮食资源紧张问题,促进资源可持续利用,构建水-能源-粮食系统,利用耦合协调度模型对我国的30个省(自治区、直辖市)进行测算,并利用空间杜宾模型分析主要影响因素。结果表明:2003—2017年,我国能源、粮食评价[JP]指数高于水资源评价指数,系统综合评价指数逐年递增;大部分省份耦合协调度处于初级协调水平且呈现逐年上升的态势,个别省份耦合协调度濒临失调;耦合协调度空间自相关性较强,虽有明显波动,但是呈现逐年加强的态势;影响耦合协调度的主要因素有从业人口数、固定资产投资额、人均生产总值、人口总数、[JP]文盲人口占比、工业污染排放、城镇化。 相似文献
9.
Anisse Pereira Hong C. Lee Robert Lammert Jr. Cailyn Wolberg Jr. Danyi Ma Chad Immoos Federico Casassa Iksoon Kang 《International Journal of Food Science & Technology》2022,57(3):1814-1823
This study was conducted to evaluate the effect of red-wine grape pomaces on the quality and sensory attributes of beef hamburger patties. Both phenolic content and antioxidant activity were assessed using Syrah, Merlot and Cabernet Sauvignon pomaces. Following the assessment, hamburger patties were prepared with Merlot pomace at 0%, 2% and 4% for the patty quality and sensory attributes. Grape seeds possessed significantly higher phenolics and antioxidant activities over the seedless pomace (P < 0.05), whereas no significant difference was found for phenolics and antioxidant activities within the seeds and seedless pomaces. The patty pH decreased as the pomace was added for 2% and 4%. Colour values (L*, a* and b*) of patties lowered as the pomace was added. Allo-Kramer shear force and hardness values increased while cooking yield decreased (P < 0.05) with the addition of pomace. No significant difference between control and Merlot patties was found for flavour, juiciness and colour, whereas lower sensory attributes were observed for texture, taste and overall acceptability. It is observed that the addition of fermented red-wine grape pomace provides hamburger patties with health promoting factors such as antioxidant and other functional components, but it also provided darker, sourer and lower cooking yield. 相似文献
10.