全文获取类型
收费全文 | 20477篇 |
免费 | 1050篇 |
国内免费 | 481篇 |
专业分类
电工技术 | 744篇 |
技术理论 | 1篇 |
综合类 | 1745篇 |
化学工业 | 3174篇 |
金属工艺 | 732篇 |
机械仪表 | 804篇 |
建筑科学 | 1968篇 |
矿业工程 | 521篇 |
能源动力 | 405篇 |
轻工业 | 1894篇 |
水利工程 | 374篇 |
石油天然气 | 399篇 |
武器工业 | 72篇 |
无线电 | 840篇 |
一般工业技术 | 2861篇 |
冶金工业 | 1118篇 |
原子能技术 | 196篇 |
自动化技术 | 4160篇 |
出版年
2024年 | 61篇 |
2023年 | 210篇 |
2022年 | 295篇 |
2021年 | 403篇 |
2020年 | 452篇 |
2019年 | 452篇 |
2018年 | 418篇 |
2017年 | 521篇 |
2016年 | 599篇 |
2015年 | 624篇 |
2014年 | 1134篇 |
2013年 | 1156篇 |
2012年 | 1354篇 |
2011年 | 1632篇 |
2010年 | 1239篇 |
2009年 | 1246篇 |
2008年 | 1017篇 |
2007年 | 1232篇 |
2006年 | 1072篇 |
2005年 | 910篇 |
2004年 | 822篇 |
2003年 | 733篇 |
2002年 | 627篇 |
2001年 | 511篇 |
2000年 | 411篇 |
1999年 | 403篇 |
1998年 | 332篇 |
1997年 | 295篇 |
1996年 | 216篇 |
1995年 | 238篇 |
1994年 | 158篇 |
1993年 | 147篇 |
1992年 | 110篇 |
1991年 | 91篇 |
1990年 | 86篇 |
1989年 | 86篇 |
1988年 | 89篇 |
1987年 | 59篇 |
1986年 | 49篇 |
1985年 | 69篇 |
1984年 | 78篇 |
1983年 | 89篇 |
1982年 | 91篇 |
1981年 | 29篇 |
1980年 | 34篇 |
1979年 | 21篇 |
1978年 | 19篇 |
1977年 | 18篇 |
1959年 | 5篇 |
1955年 | 11篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
ABSTRACTCommunity development service practitioners have been increasingly burdened with a broader range of responsibilities and ICT could enhance their productivity. Therefore, it is prudent to incorporate information communication technology (ICT) skills into the skills matrix required by the practitioners in order to deliver the service effectively. Furthermore, ICT use is prevalent in almost every organization, therefore, ICT can also serve as a major factor in flexibility of delivery of community development service to the communities, but only if the practitioners possess adequate skills in using ICT tools (software applications) in retrieving, presenting and disseminating valuable and adequate information within the workplace to the parties involved. The study determines the current work conditions, level of performance and expertise in the use of ICT among community development workers (CDWs) in KwaZulu-Natal, South Africa, by evaluating their abilities and experiences, with a view to identify the areas to enhance their effectiveness. Determining the competency of their use of ICT applications is not an easy task; thus a survey methodology was adopted, with a sample of 189 CDWs (63% female and 37% male). Respondents were given the opportunity to rate of their own current ability to use common computer software applications. 相似文献
92.
王银锁 《自动化与仪器仪表》2013,(6):86-87
介绍了电磁流量计的工作原理,电磁流量计的精度、口径和传感器绝缘衬里选择;一体电磁流量计和分体式电磁流量计的安装;电磁流量计在使用过程中故障现象和处理方法。 相似文献
93.
介绍了9F燃机发电机主变压器的绕组温度计异常现象的分析和处理及绕组温度测量的热模拟法和改进建议. 相似文献
94.
基于对信息需求的硬性需求,随着通信技术、显示技术、数据版权和计算机技术的飞速发展,移动阅读悄然进入我们的生活,改变着我们传统的阅读方式,由此也产生了信息量无限大而又具备纸质阅读感受的移动阅读终端。本文首先对移动阅读终端的软、硬件和功能进行介绍,进而简要介绍移动阅读终端的测试方法,最后对移动阅读终端发展进行了展望。 相似文献
95.
Liliana Marinescu Denisa Ficai Anton Ficai Ovidiu Oprea Adrian Ionut Nicoara Bogdan Stefan Vasile Laura Boanta Alexandru Marin Ecaterina Andronescu Alina-Maria Holban 《International journal of molecular sciences》2022,23(11)
The synthesis of nanoparticles from noble metals has received high attention from researchers due to their unique properties and their wide range of applications. Silver nanoparticles (AgNPs), in particular, show a remarkable inhibitory effect against microorganisms and viruses. Various methods have been developed to obtain AgNPs, however the stability of such nanostructures over time is still challenging. Researchers attempt to obtain particular shapes and sizes in order to tailor AgNPs properties for specific areas, such as biochemistry, biology, agriculture, electronics, medicine, and industry. The aim of this study was to design AgNPs with improved antimicrobial characteristics and stability. Two different wet chemical routes were considered: synthesis being performed (i) reduction method at room temperatures and (ii) solvothermal method at high temperature. Here, we show that the antimicrobial properties of the obtained AgNPs, are influenced by their synthesis route, which impact on the size and shape of the structures. This work analyses and compares the antimicrobial properties of the obtained AgNPs, based on their structure, sizes and morphologies which are influenced, in turn, not only by the type or quantities of precursors used but also by the temperature of the reaction. Generally, AgNPs obtained by solvothermal, at raised temperature, registered better antimicrobial activity as compared to NPs obtained by reduction method at room temperature. 相似文献
96.
97.
98.
Reinaldo Sousa Dos Santos Regla María Medina-Gali Ignacio Babiloni-Chust Laura Marroqui Angel Nadal 《International journal of molecular sciences》2022,23(9)
There is a need to develop identification tests for Metabolism Disrupting Chemicals (MDCs) with diabetogenic activity. Here we used the human EndoC-βH1 β-cell line, the rat β-cell line INS-1E and dispersed mouse islet cells to assess the effects of endocrine disruptors on cell viability and glucose-stimulated insulin secretion (GSIS). We tested six chemicals at concentrations within human exposure (from 0.1 pM to 1 µM). Bisphenol-A (BPA) and tributyltin (TBT) were used as controls while four other chemicals, namely perfluorooctanoic acid (PFOA), triphenylphosphate (TPP), triclosan (TCS) and dichlorodiphenyldichloroethylene (DDE), were used as “unknowns”. Regarding cell viability, BPA and TBT increased cell death as previously observed. Their mode of action involved the activation of estrogen receptors and PPARγ, respectively. ROS production was a consistent key event in BPA-and TBT-treated cells. None of the other MDCs tested modified viability or ROS production. Concerning GSIS, TBT increased insulin secretion while BPA produced no effects. PFOA decreased GSIS, suggesting that this chemical could be a “new” diabetogenic agent. Our results indicate that the EndoC-βH1 cell line is a suitable human β-cell model for testing diabetogenic MDCs. Optimization of the test methods proposed here could be incorporated into a set of protocols for the identification of MDCs. 相似文献
99.
100.
Rafael K. de Andrades Márcio Dorn Daniel S. Farenzena Luis C. Lamb 《Expert systems with applications》2013,40(13):5210-5218
The Medical and Pharmaceutical industries have shown high interest in the precise engineering of protein hormones and enzymes that perform existing functions under a wide range of conditions. Proteins are responsible for the execution of different functions in the cell: catalysis in chemical reactions, transport and storage, regulation and recognition control. Computational Protein Design (CPD) investigates the relationship between 3-D structures of proteins and amino acid sequences and looks for all sequences that will fold into such 3-D structure. Many computational methods and algorithms have been proposed over the last years, but the problem still remains a challenge for Mathematicians, Computer Scientists, Bioinformaticians and Structural Biologists. In this article we present a new method for the protein design problem. Clustering techniques and a Dead-End-Elimination algorithm are combined with a SAT problem representation of the CPD problem in order to design the amino acid sequences. The obtained results illustrate the accuracy of the proposed method, suggesting that integrated Artificial Intelligence techniques are useful tools to solve such an intricate problem. 相似文献