全文获取类型
收费全文 | 5604篇 |
免费 | 304篇 |
国内免费 | 209篇 |
专业分类
电工技术 | 75篇 |
技术理论 | 6篇 |
综合类 | 536篇 |
化学工业 | 305篇 |
金属工艺 | 97篇 |
机械仪表 | 194篇 |
建筑科学 | 1569篇 |
矿业工程 | 81篇 |
能源动力 | 82篇 |
轻工业 | 267篇 |
水利工程 | 143篇 |
石油天然气 | 545篇 |
武器工业 | 15篇 |
无线电 | 135篇 |
一般工业技术 | 397篇 |
冶金工业 | 743篇 |
原子能技术 | 50篇 |
自动化技术 | 877篇 |
出版年
2024年 | 11篇 |
2023年 | 40篇 |
2022年 | 90篇 |
2021年 | 116篇 |
2020年 | 138篇 |
2019年 | 97篇 |
2018年 | 90篇 |
2017年 | 139篇 |
2016年 | 151篇 |
2015年 | 167篇 |
2014年 | 327篇 |
2013年 | 357篇 |
2012年 | 318篇 |
2011年 | 442篇 |
2010年 | 325篇 |
2009年 | 358篇 |
2008年 | 334篇 |
2007年 | 358篇 |
2006年 | 338篇 |
2005年 | 278篇 |
2004年 | 222篇 |
2003年 | 233篇 |
2002年 | 227篇 |
2001年 | 162篇 |
2000年 | 126篇 |
1999年 | 109篇 |
1998年 | 70篇 |
1997年 | 52篇 |
1996年 | 45篇 |
1995年 | 39篇 |
1994年 | 43篇 |
1993年 | 22篇 |
1992年 | 33篇 |
1991年 | 16篇 |
1990年 | 21篇 |
1989年 | 16篇 |
1988年 | 15篇 |
1987年 | 22篇 |
1986年 | 10篇 |
1985年 | 14篇 |
1984年 | 15篇 |
1983年 | 13篇 |
1982年 | 6篇 |
1981年 | 6篇 |
1974年 | 7篇 |
1968年 | 6篇 |
1961年 | 5篇 |
1959年 | 10篇 |
1957年 | 7篇 |
1954年 | 14篇 |
排序方式: 共有6117条查询结果,搜索用时 136 毫秒
1.
学习不仅仅是自然科学知识的学习,更是社会科学、民族文化、正确人生观和价值观的形成过程,“课程思政”无疑正是实现该目标的捷径,它是当前高等院校思想政治教育的新模式。如何提升学生解决“复杂工程问题”的能力成为高校开展工程教育和“新工科”的难点和重点,而课程思政正是培养学生解决“复杂工程问题”中所需要的非技术因素的重要途径。“自动控制系统工程设计”是自动化专业高年级学生的一门专业课,当前关于“课程思政”的论述是指导思想居多、实施经验以及案例设计较少,针对该问题以“自动控制系统工程设计”为例,详细给出了“课程思政”教学案例的具体实施过程,对同类课程提供参考。 相似文献
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.
4.
ContextEnterprise software systems (e.g., enterprise resource planning software) are often deployed in different contexts (e.g., different organizations or different business units or branches of one organization). However, even though organizations, business units or branches have the same or similar business goals, they may differ in how they achieve these goals. Thus, many enterprise software systems are subject to variability and adapted depending on the context in which they are used.ObjectiveOur goal is to provide a snapshot of variability in large scale enterprise software systems. We aim at understanding the types of variability that occur in large industrial enterprise software systems. Furthermore, we aim at identifying how variability is handled in such systems.MethodWe performed an exploratory case study in two large software organizations, involving two large enterprise software systems. Data were collected through interviews and document analysis. Data were analyzed following a grounded theory approach.ResultsWe identified seven types of variability (e.g., functionality, infrastructure) and eight mechanisms to handle variability (e.g., add-ons, code switches).ConclusionsWe provide generic types for classifying variability in enterprise software systems, and reusable mechanisms for handling such variability. Some variability types and handling mechanisms for enterprise software systems found in the real world extend existing concepts and theories. Others confirm findings from previous research literature on variability in software in general and are therefore not specific to enterprise software systems. Our findings also offer a theoretical foundation for describing variability handling in practice. Future work needs to provide more evaluations of the theoretical foundations, and refine variability handling mechanisms into more detailed practices. 相似文献
5.
This paper presents an innovative solution to model distributed adaptive systems in biomedical environments. We present an original TCBR-HMM (Text Case Based Reasoning-Hidden Markov Model) for biomedical text classification based on document content. The main goal is to propose a more effective classifier than current methods in this environment where the model needs to be adapted to new documents in an iterative learning frame. To demonstrate its achievement, we include a set of experiments, which have been performed on OSHUMED corpus. Our classifier is compared with Naive Bayes and SVM techniques, commonly used in text classification tasks. The results suggest that the TCBR-HMM Model is indeed more suitable for document classification. The model is empirically and statistically comparable to the SVM classifier and outperforms it in terms of time efficiency. 相似文献
6.
为了提高设计创新效率,本研究基于心理图式提出了国庆彩车的设计程序与方法。研究按照浅层、中层和深层的次序递进,设计心理图式划分为“造型图式”“叙事与动作图式”以及“人物和情感图式”的基本类别,并提出了综合性、时态性、差异性和集体性四类基本属性。而后结合新中国成立70周年彩车设计,对不同心理图式的应用方法和属性进行了案例分析。本文所提出的方法在设计实践中得到了实证,具有一定的实用价值。 相似文献
7.
8.
东营凹陷王庄-宁海地区流体包裹体分析与流体充注研究 总被引:5,自引:4,他引:1
李传华 《油气地质与采收率》2006,13(1):34-36
利用流体包裹体分析技术,系统地分析了东营凹陷王庄-宁海地区覆盖所有含油层位的流体包裹体样品。包裹体荧光观察和均一温度特征分析揭示了包裹体发育期次为5期,说明该区油藏存在5次流体充注过程;据此确定了备期烃类的成藏期次。东营组沉积时期和明化镇组沉积末期的油气运聚均在成藏后遭受大气淡水淋滤和降解作用。沙三段原油可能经历至少2期稠油化作用。荧光观察进一步证实该区主要发生2期充注、2期成藏。 相似文献
9.
陆东凹陷油气藏烃类组成非均质性及其意义 总被引:1,自引:1,他引:0
陆东凹陷原油和油砂抽提物中烃类的宏观组成存在着明显的非均质性。在高孔隙度(>15%)储层单元中,饱和烃的含量高,占总组成的含量均大于40%,而极性化合物则相对较低,一般不足40%;相反,在低孔隙度(<15%)储层单元中,饱和烃的含量明显降低,而极性化合物则显著增加。此外,陆东凹陷原油和油砂抽提物中烃类成熟度亦存在着非均质性:在高孔隙度储层中,原油和油砂烃类的成熟度参数高,而在低孔隙度储层中原油和油砂烃类的成熟度参数低。根据原油和油砂抽提物中烃类的宏观组成特征和成熟度参数的变化规律,提出了陆东凹陷油气聚集模式。 相似文献
10.