全文获取类型
收费全文 | 2343篇 |
免费 | 358篇 |
国内免费 | 157篇 |
专业分类
电工技术 | 213篇 |
综合类 | 134篇 |
化学工业 | 368篇 |
金属工艺 | 223篇 |
机械仪表 | 144篇 |
建筑科学 | 220篇 |
矿业工程 | 111篇 |
能源动力 | 93篇 |
轻工业 | 164篇 |
水利工程 | 66篇 |
石油天然气 | 185篇 |
武器工业 | 22篇 |
无线电 | 233篇 |
一般工业技术 | 251篇 |
冶金工业 | 87篇 |
原子能技术 | 43篇 |
自动化技术 | 301篇 |
出版年
2024年 | 30篇 |
2023年 | 74篇 |
2022年 | 189篇 |
2021年 | 248篇 |
2020年 | 141篇 |
2019年 | 93篇 |
2018年 | 91篇 |
2017年 | 131篇 |
2016年 | 104篇 |
2015年 | 168篇 |
2014年 | 162篇 |
2013年 | 175篇 |
2012年 | 172篇 |
2011年 | 184篇 |
2010年 | 139篇 |
2009年 | 128篇 |
2008年 | 119篇 |
2007年 | 124篇 |
2006年 | 96篇 |
2005年 | 56篇 |
2004年 | 42篇 |
2003年 | 32篇 |
2002年 | 20篇 |
2001年 | 13篇 |
2000年 | 25篇 |
1999年 | 26篇 |
1998年 | 9篇 |
1997年 | 15篇 |
1996年 | 17篇 |
1995年 | 10篇 |
1994年 | 5篇 |
1993年 | 6篇 |
1992年 | 5篇 |
1991年 | 1篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1986年 | 1篇 |
1985年 | 1篇 |
1984年 | 2篇 |
1980年 | 1篇 |
1959年 | 1篇 |
排序方式: 共有2858条查询结果,搜索用时 0 毫秒
1.
Effects of different carbon sources and C/N values on nonvolatile taste components of Pleurotus eryngii
下载免费PDF全文
![点击此处可从《International Journal of Food Science & Technology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Wen Li Xiaobei Li Yan Yang Feng Zhou Yanfang Liu Shuai Zhou Hailong Yu 《International Journal of Food Science & Technology》2015,50(11):2360-2366
Pleurotus eryngii, the second largest industrial cultivation mushroom in China, is usually cultivated on substrates mainly consisting of sawdust and corncob. In this study, experiments were performed to determine the effects of different carbon sources and C/N values on nonvolatile taste components of P. eryngii. The effects of different carbon sources on nonvolatile taste components levels revealed that sawdust was beneficial to high levels of crude protein, amino acids, 5′‐nucleotides and equivalent umami concentration, while corncob was beneficial to high contents of carbohydrate, polysaccharides and trehalose. At the similar C/N values, relatively higher sawdust content was beneficial to umami amino acid production, while relatively higher corncob content was beneficial to high contents of carbohydrate, polysaccharides and mannitol. Higher C/N value was beneficial to high levels of crude protein, amino acids, 5′‐nucleotides and equivalent umami concentration, while lower C/N value was beneficial to high contents of carbohydrate, polysaccharides and trehalose. These results provided information for P. eryngii fruit body industrial cultivation to obtain specific nonvolatile taste components with high levels. 相似文献
2.
Thermal comfort is an important factor for the design of buildings. Although it has been well recognized that many physiological parameters are linked to the state of thermal comfort or discomfort of humans, how to use physiological signal to judge the state of thermal comfort has not been well studied. In this paper, the feasibility of continuously determining feelings of personal thermal comfort was discussed by using electroencephalogram (EEG) signals in private space. In the study, 22 subjects were exposed to thermally comfortable and uncomfortably hot environments, and their EEG signals were recorded. Spectral power features of the EEG signals were extracted, and an ensemble learning method using linear discriminant analysis or support vector machine as a sub-classifier was used to build the discriminant model. The results show that an average discriminate accuracy of 87.9% can be obtained within a detection window of 60 seconds. This study indicates that it is feasible to distinguish whether a person feels comfortable or too hot in their private space by multi-channel EEG signals without interruption and suggests possibility for further applications in neuroergonomics. 相似文献
3.
H9000 V4.0计算机监控系统技术特点概要 总被引:8,自引:3,他引:5
为了满足三峡右岸电站的应用需要,在H9000 V3.0计算机监控系统的基础上研制开发了H9000 V4.0系统,改进和完善了原系统已有功能,开发了新功能,进一步提高了系统的性能指标和可靠性指标。文中主要介绍H9000 V4.0系统的设计原则,以及数据采集、人机联系、报表定制、Web信息发布、历史数据管理等主要新功能。 相似文献
4.
5.
Large-scale data-intensive cloud computing with the MapReduce framework is becoming pervasive for the core business of many
academic, government, and industrial organizations. Hadoop, a state-of-the-art open source project, is by far the most successful
realization of MapReduce framework. While MapReduce is easy- to-use, efficient and reliable for data-intensive computations,
the excessive configuration parameters in Hadoop impose unexpected challenges on running various workloads with a Hadoop cluster
effectively. Consequently, developers who have less experience with the Hadoop configuration system may devote a significant
effort to write an application with poor performance, either because they have no idea how these configurations would influence
the performance, or because they are not even aware that these configurations exist. There is a pressing need for comprehensive
analysis and performance modeling to ease MapReduce application development and guide performance optimization under different
Hadoop configurations. In this paper, we propose a statistical analysis approach to identify the relationships among workload
characteristics, Hadoop configurations and workload performance. We apply principal component analysis and cluster analysis
to 45 different metrics, which derive relationships between workload characteristics and corresponding performance under different
Hadoop configurations. Regression models are also constructed that attempt to predict the performance of various workloads
under different Hadoop configurations. Several non-intuitive relationships between workload characteristics and performance
are revealed through our analysis and the experimental results demonstrate that our regression models accurately predict the
performance of MapReduce workloads under different Hadoop configurations. 相似文献
6.
7.
8.
二硼化锆基超高温陶瓷的制备及性能 总被引:1,自引:0,他引:1
用碳化硅(SiC)颗粒增韧二硼化锆(ZrB2)陶瓷,在氩气流中热压烧结温度为1 950℃、保温1 h,20 MPa压力下成功制备出了致密的ZrB2/SiCp复合材料.ZrB2/SiCp复合材料的致密度随着SiC颗粒添加量的增加而增加.当SiC颗粒的体积分数(下同)为15%时,相对致密度达到100%.ZrB2/SiCp复合材料的抗弯强度和断裂韧性都随着SiC添加量的增加成上升趋势,当SiC颗粒的添加量在15%时同时达得最大值,分别为646 MPa和8.52 MPam·m1/2.SiCp的添加还提高了ZrB2/SiCp复合材料的耐氧化烧蚀性能. 相似文献
9.
Chong Huang Yafei Li Hailong Zhang Qingsheng Liu 《International journal of remote sensing》2014,35(8):2822-2834
The alpine ecosystem is one of the most fragile ecosystems threatened by global climate change. The impact of climate variability on the vegetation dynamics of alpine ecosystems has become important in global change studies. In this study, spatially explicit gridded data, including the Moderate Resolution Imaging Spectroradiometer (MODIS) land-surface temperature (LST) product (MOD11A1/A2), the Tropical Rainfall Measuring Mission (TRMM) rainfall product (3B43), and MODIS net primary productivity (NPP) product (MOD17A3), together with meteorological observation data, were used to explore the spatio-temporal pattern of climate variability and its impact on vegetation dynamics from 2000 to 2012 in the Lancang River headwater area. We found that the variation patterns of LST, precipitation, and NPP in the study area showed remarkable spatial differences. From the northwest to the southeast the spatial variation of average annual LST exhibited a decreasing–increasing–decreasing–increasing pattern. At the same time, most of the study area exhibited an increasing LST during the growing season. The annual precipitation increased in the semi-arid northern part, whereas it decreased in the semi-humid southern part. The precipitation variability during the growing season has a pattern similar to the annual precipitation variability. Although the majority of the regions have seen an NPP increase from 2000 to 2012, the responses of the vegetation to the varied climate factors were spatially heterogeneous. The alpine–subalpine meadows in the high-altitude areas were more sensitive to climate variability in the growing season. It is argued that satellite remote-sensing products have great potential in investigating the impact of climate variability on vegetation dynamics at the finer scale, especially for the Lancang River headwater area with complex surface heterogeneity. 相似文献
10.