全文获取类型
收费全文 | 232811篇 |
免费 | 16958篇 |
国内免费 | 8577篇 |
专业分类
电工技术 | 12297篇 |
技术理论 | 15篇 |
综合类 | 12904篇 |
化学工业 | 38305篇 |
金属工艺 | 13545篇 |
机械仪表 | 14568篇 |
建筑科学 | 14627篇 |
矿业工程 | 6161篇 |
能源动力 | 5737篇 |
轻工业 | 13487篇 |
水利工程 | 4074篇 |
石油天然气 | 14450篇 |
武器工业 | 1483篇 |
无线电 | 24340篇 |
一般工业技术 | 35053篇 |
冶金工业 | 14435篇 |
原子能技术 | 5519篇 |
自动化技术 | 27346篇 |
出版年
2023年 | 3219篇 |
2022年 | 5790篇 |
2021年 | 8600篇 |
2020年 | 6512篇 |
2019年 | 5624篇 |
2018年 | 7051篇 |
2017年 | 7667篇 |
2016年 | 6887篇 |
2015年 | 8017篇 |
2014年 | 10422篇 |
2013年 | 12743篇 |
2012年 | 13568篇 |
2011年 | 14783篇 |
2010年 | 12599篇 |
2009年 | 12254篇 |
2008年 | 12035篇 |
2007年 | 11439篇 |
2006年 | 10914篇 |
2005年 | 9504篇 |
2004年 | 6964篇 |
2003年 | 6706篇 |
2002年 | 6542篇 |
2001年 | 5885篇 |
2000年 | 5479篇 |
1999年 | 5254篇 |
1998年 | 4294篇 |
1997年 | 3563篇 |
1996年 | 3302篇 |
1995年 | 2855篇 |
1994年 | 2343篇 |
1993年 | 1914篇 |
1992年 | 1728篇 |
1991年 | 1478篇 |
1990年 | 1397篇 |
1989年 | 1246篇 |
1988年 | 1099篇 |
1987年 | 966篇 |
1986年 | 852篇 |
1985年 | 799篇 |
1984年 | 754篇 |
1982年 | 707篇 |
1981年 | 695篇 |
1979年 | 749篇 |
1978年 | 780篇 |
1977年 | 746篇 |
1976年 | 763篇 |
1975年 | 718篇 |
1974年 | 721篇 |
1973年 | 724篇 |
1972年 | 707篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
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
92.
Colour remains one of the key factors in presenting an object and, consequently, has been widely applied in retrieval of images based on their visual contents. However, a colour appearance changes with the change of viewing surroundings, the phenomenon that has not been paid attention yet while performing colour‐based image retrieval. To comprehend this effect, in this article, a chromatic contrast model, CAMcc, is developed for the application of retrieval of colour intensive images, cementing the gap that most of existing colour models lack to fill by taking simultaneous colour contrast into account. Subsequently, the model is applied to the retrieval task on a collection of museum wallpapers of colour‐rich images. In comparison with current popular colour models including CIECAM02, HSI and RGB, with respect to both foreground and background colours, CAMcc appears to outperform the others with retrieved results being closer to query images. In addition, CAMcc focuses more on foreground colours, especially by maintaining the balance between both foreground and background colours, while the rest of existing models take on dominant colours that are perceived the most, usually background tones. Significantly, the contribution of the investigation lies in not only the improvement of the accuracy of colour‐based image retrieval but also the development of colour contrast model that warrants an important place in colour and computer vision theory, leading to deciphering the insight of this age‐old topic of chromatic contrast in colour science. © 2014 Wiley Periodicals, Inc. Col Res Appl, 40, 361–373, 2015 相似文献
93.
94.
95.
96.
97.
Guo-Yu Li Ya-Xin Zheng Fu-Zhou Sun Jian Huang Meng-Meng Lou Jing-Kai Gu Jin-Hui Wang 《International journal of molecular sciences》2015,16(9):22190-22204
This study aimed at investigating the possible mechanisms of hepatic protective activity of Cichorium intybus L. (chicory) in acute liver injury. Pathological observation, reactive oxygen species (ROS) detection and measurements of biochemical indexes on mouse models proved hepatic protective effect of Cichorium intybus L. Identification of active compounds in Cichorium intybus L. was executed through several methods including ultra performance liquid chromatography/time of flight mass spectrometry (UPLC-TOF-MS). Similarity ensemble approach (SEA) docking, molecular modeling, molecular docking, and molecular dynamics (MD) simulation were applied in this study to explore possible mechanisms of the hepato-protective potential of Cichorium intybus L. We then analyzed the chemical composition of Cichorium intybus L., and found their key targets. Furthermore, in vitro cytological examination and western blot were used for validating the efficacy of the selected compounds. In silico analysis and western blot together demonstrated that selected compound 10 in Cichorium intybus L. targeted Akt-1 in hepatocytes. Besides, compound 13 targeted both caspase-1 and Akt-1. These small compounds may ameliorate liver injury by acting on their targets, which are related to apoptosis or autophagy. The conclusions above may shed light on the complex molecular mechanisms of Cichorium intybus L. acting on hepatocytes and ameliorating liver injury. 相似文献
98.
99.
100.
随着FPGA技术和电力电机技术的发展,FPGA+ARM的集成方式已经成为FPGA的发展方向.针对一体化多轴运动控制与驱动的特点,选用了集成双核ARM CPU与FPGA结合的Xilinx Zynq-7020全可编程System-on-chip(SoC)作为硬件平台,一个ARM CPU完成多轴的位置环、速度环和电流环的算法以及多轴轨迹生成,能同时完成伺服高级算法如谐振等,另一个ARM CPU完成交互功能,发挥FPGA高速运算的功能,完成6轴电流环流水线控制以及双采样双更新电流环算法.提高了系统整体带宽,实现多轴ns级同步精度以实现更精确的位置轨迹,驱控一体内部数据通过共享内存以及高速内部总线的方式进行交换,其传输速度更快、传输信息更加丰富. 相似文献