全文获取类型
收费全文 | 5997篇 |
免费 | 178篇 |
国内免费 | 42篇 |
专业分类
电工技术 | 159篇 |
综合类 | 63篇 |
化学工业 | 1338篇 |
金属工艺 | 142篇 |
机械仪表 | 183篇 |
建筑科学 | 274篇 |
矿业工程 | 36篇 |
能源动力 | 229篇 |
轻工业 | 1064篇 |
水利工程 | 68篇 |
石油天然气 | 79篇 |
武器工业 | 14篇 |
无线电 | 271篇 |
一般工业技术 | 775篇 |
冶金工业 | 591篇 |
原子能技术 | 58篇 |
自动化技术 | 873篇 |
出版年
2025年 | 9篇 |
2024年 | 97篇 |
2023年 | 73篇 |
2022年 | 170篇 |
2021年 | 262篇 |
2020年 | 204篇 |
2019年 | 215篇 |
2018年 | 227篇 |
2017年 | 244篇 |
2016年 | 227篇 |
2015年 | 221篇 |
2014年 | 266篇 |
2013年 | 501篇 |
2012年 | 339篇 |
2011年 | 388篇 |
2010年 | 317篇 |
2009年 | 247篇 |
2008年 | 232篇 |
2007年 | 184篇 |
2006年 | 156篇 |
2005年 | 104篇 |
2004年 | 134篇 |
2003年 | 142篇 |
2002年 | 164篇 |
2001年 | 98篇 |
2000年 | 87篇 |
1999年 | 80篇 |
1998年 | 174篇 |
1997年 | 122篇 |
1996年 | 60篇 |
1995年 | 50篇 |
1994年 | 63篇 |
1993年 | 51篇 |
1992年 | 26篇 |
1991年 | 15篇 |
1990年 | 18篇 |
1989年 | 22篇 |
1988年 | 18篇 |
1986年 | 11篇 |
1985年 | 17篇 |
1984年 | 12篇 |
1983年 | 12篇 |
1982年 | 17篇 |
1981年 | 11篇 |
1980年 | 13篇 |
1979年 | 7篇 |
1977年 | 12篇 |
1976年 | 28篇 |
1975年 | 8篇 |
1974年 | 7篇 |
排序方式: 共有6217条查询结果,搜索用时 15 毫秒
1.
The alarm lists presented to control center operators are usually difficult to interpret. The authors present an expert system that processes the alarm lists in Portuguese control centers. This system makes an intelligent synthesis of the available information and presents it in a flexible and structured way. It uses an original approach to deal with temporal reasoning and real-time constraints. The system incorporates an explanation module that enables its use as a tutor for novice operators 相似文献
2.
Cristiane Vieira Helm Alicia de Francisco Salete Aparecida Gaziola Ricardo Francisco Fornazier Georgia Bertoni Pompeu Ricardo Antunes Azevedo 《Food Biotechnology》2005,18(3):327-341
Barley (Hordeum vulgare L.) has had an important impact on human nutrition. Hull-less barley is a genetically improved type that has been widely used in recent years. Six Brazilian hull-less barley varieties (IAC-IBON 214-82; IAC 8612-421; IAC 8501-31; IAC 8501-12; IAPAR 39-ACUMAI; IAC 8501-22) were analyzed for storage protein constituents, amino acid contents, and similarity among the hull-less barley varieties. Albumins, globulins, prolamins I and II, and glutelins were extracted and separated by SDS-PAGE. The total protein amino acid contents of the flour were also determined for each variety by TLC and HPLC. Variations in intensity and appearance and disappearance of protein bands were observed among the varieties suggesting genetic variability. However, the amino acid profile did not indicate any major variations in the amino acid concentrations. The high lysine and threonine total concentrations detected in the seeds of the hull-less barley varieties encouraged an investigation into the regulation of amino acid metabolism and storage protein synthesis. 相似文献
3.
4.
Isolation and preliminary characterization of Pichia pinus mutants insensitive to glucose repression
A new method for the isolation of glucose repression-insensitive mutants in the methylotrophic yeast Pichia pinus was developed. The method is based on screening of small suspension samples derived from 2-deoxyglucose-resistant colonies for alcohol oxidase activity. Alcohol oxidase activity was evaluated by determination of formaldehyde excreted by cells. Mutants with glucose non-repressible alcohol oxidase and catalase synthesis were obtained. All mutants grew poorly on D -xylose compared to the wild type, whereas growth on L -arabinose was similar to the wild type. Changes in the glucose transport system were suggested to be responsible for altered growth characteristics and defective glucose repression. 相似文献
5.
6.
This paper presents a testing methodology to apply Behaviour Driven Development (BDD) techniques while developing Multi-Agent Systems (MASs), termed BEhavioural Agent Simple Testing (BEAST) Methodology. This methodology is supported by the open source framework (BEAST Tool) which automatically generates test cases skeletons from BDD scenarios specifications. The developed framework allows the testing of MASs based on JADE or JADEX platforms. In addition, this framework offers a set of configurable Mock Agents with the aim of being able to execute tests while the MAS is under development. The BEAST Methodology presents transparent traceability from user requirements to test cases. Thus, the stakeholders can be aware of the project status. The methodology and the associated tool have been validated in the development of a MAS for fault diagnosis in FTTH (Fiber To The Home) networks. The results have been measured in quantifiable way obtaining a reduction of the tests implementation time. 相似文献
7.
Natacha Kalline de Oliveira Lucyene Miguita Tais Helena Costa Salles Marcos Akira d’Ávila Márcia Martins Marques Maria Cristina Zindel Deboni 《Journal of Materials Science》2018,53(23):15757-15768
The aim of this study was to analyze the influence of nanoporous structure of polymeric biomaterials on the in vitro osteogenic induction of human stem cells. An electronic search in three databases (MEDLINE, SCOPUS, and Web of Science) was performed for articles that were published before May 2018. In vitro studies were included if they met the following criteria: (1) the use of polymeric scaffolds (natural or synthetic); (2) the co-culture of human stem cells with the scaffold; and (3) cell viability, proliferation, and osteogenic differentiation assays. The main characteristics of the published studies were summarized, and a quality assessment tool was used to analyze methodological features. Eighty-eight potential articles were firstly retrieved. Thirteen were eligible for qualitative analysis. Only three studies characterized cell stemness. Nanostructure of the scaffolds showed a significant influence on viability, proliferation, and osteogenic differentiation of human stem cells. Combination of porosity between 72 and 93% and a large range diameter between 50 and 224 μm resulted in more remarkable cellular proliferation and differentiation. Porous polymeric scaffolds can be functionalized by stem cells leading to osteogenic induction. High standards of laboratory practice and accurate methodological reporting are essential for the credibility of the results. 相似文献
8.
9.
10.
Abstract A simple geometrical model has been proposed for a citrus canopy. We assume the citrus orchard to be a lattice structure, with the trees positioned at its points and where the composite-scene reflectance is the sum of the reflectance of its individual components as weighted by their respective surfaces within a unit area. The model has been used to analyse the citrus spectral response obtained from Landsat-5 TM images for winter and summer, where the status of the orchard is different. The correlations between spectral and geometrical data show the influence of per cent crop cover, shadows and background in the composite scene reflectance. We conclude that the summer images could be more useful than the winter ones for parcel classification according to per cent crop cover. 相似文献