全文获取类型
收费全文 | 41089篇 |
免费 | 5059篇 |
国内免费 | 3638篇 |
专业分类
电工技术 | 4653篇 |
技术理论 | 3篇 |
综合类 | 4061篇 |
化学工业 | 4952篇 |
金属工艺 | 3034篇 |
机械仪表 | 2813篇 |
建筑科学 | 3264篇 |
矿业工程 | 1436篇 |
能源动力 | 1162篇 |
轻工业 | 3469篇 |
水利工程 | 1153篇 |
石油天然气 | 1418篇 |
武器工业 | 661篇 |
无线电 | 4537篇 |
一般工业技术 | 4156篇 |
冶金工业 | 1907篇 |
原子能技术 | 650篇 |
自动化技术 | 6457篇 |
出版年
2024年 | 292篇 |
2023年 | 876篇 |
2022年 | 1654篇 |
2021年 | 2334篇 |
2020年 | 1611篇 |
2019年 | 1102篇 |
2018年 | 1275篇 |
2017年 | 1431篇 |
2016年 | 1261篇 |
2015年 | 1936篇 |
2014年 | 2258篇 |
2013年 | 2766篇 |
2012年 | 3220篇 |
2011年 | 3408篇 |
2010年 | 3123篇 |
2009年 | 2979篇 |
2008年 | 3078篇 |
2007年 | 2913篇 |
2006年 | 2609篇 |
2005年 | 2116篇 |
2004年 | 1575篇 |
2003年 | 1158篇 |
2002年 | 1255篇 |
2001年 | 1114篇 |
2000年 | 838篇 |
1999年 | 433篇 |
1998年 | 181篇 |
1997年 | 193篇 |
1996年 | 152篇 |
1995年 | 137篇 |
1994年 | 89篇 |
1993年 | 72篇 |
1992年 | 66篇 |
1991年 | 44篇 |
1990年 | 51篇 |
1989年 | 31篇 |
1988年 | 25篇 |
1987年 | 17篇 |
1986年 | 23篇 |
1985年 | 4篇 |
1984年 | 4篇 |
1983年 | 9篇 |
1982年 | 9篇 |
1981年 | 10篇 |
1980年 | 12篇 |
1979年 | 6篇 |
1976年 | 8篇 |
1973年 | 4篇 |
1959年 | 5篇 |
1951年 | 9篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
恶意代码数量已经呈现爆炸式增长,对于恶意代码的检测防护显得尤为重要.近几年,基于深度学习的恶意代码检测方法开始出现,基于此,提出一种新的检测方法,将恶意代码二进制文件转化为十进制数组,并利用一维卷积神经网络(1 Dimention Convolutional Neural Networks,1D CNN)对数组进行分类和识别.针对代码家族之间数量不平衡的现象,该算法选择在分类预测上表现良好的XGBoost,并对Vision Research Lab中的25个不同恶意软件家族的9458个恶意软件样本进行了实验.实验结果表明,所提的方法分类预测精度达到了97%. 相似文献
3.
Dong Liu Xia Ke Zhong-Ce Hu Yu-Guo Zheng 《Journal of Bioscience and Bioengineering》2021,131(5):518-524
4.
Zhenkun Ke Xin Cao Chuanli Shan Lifen Shi Pingping Wang Yong Yang Fengyang Zhao Jiedong Cui Jinwei Li Gang Zhou Min Guan Tao Yu 《Ceramics International》2021,47(14):19605-19613
The purpose of the current work was to research the effect of alkali metal oxide on the structure, thermal properties, viscosity and chemical stability in the glass system (R2O–CaO–B2O3–SiO2) systematically. Because the glass would emulsify when Li2O was added to the glass batch, this article did not discuss Li2O. The results showed that when the amount of Na2O was less than 4 mol.%, there was a higher interconnectivity of borate and silicate sub-networks in glass, as more mixed Si–O–B bonds were present in glass. The glass samples exhibited excellent thermal properties and chemical stabilities. As the amount of Na2O exceeded 4 mol.%, the interconnectivity of borate and silicate sub-networks was weakened. The thermal properties and chemical stabilities of the glass samples were reduced. The connectivity of the silicate sub-network was weakened slightly as the Na/K ratio varied, and the coefficient of thermal expansion (CTE) of the glass samples gradually increased, and the resistance to thermal shock (RTS) value gradually decreased. Moreover, the viscosity of the glass samples decreased with the ratio of Na/Si and Na/K increased. 相似文献
5.
目的 为了解决目前三维数据隐藏算法不能兼顾无失真和盲提取的问题,提出一种新的完全无失真的三维网格模型数据隐藏盲算法。方法 首先使用混沌逻辑映射选择嵌入与提取模式,保证数据的安全性。然后利用面元素重排,完全不会造成三维模型失真的性质,通过不同嵌入模式规则对三角面元素进行重排,以嵌入秘密数据。接收端则可根据相应的提取模式规则提取秘密数据。结果 仿真结果与分析表明,该算法不会对三维模型造成任何失真,嵌入容量为每顶点2比特,且能抵抗仿射变换攻击、噪声攻击和平滑攻击等。结论 这种三维数据隐藏盲算法无失真,容量大、安全性高、鲁棒性强,适用于三维载体不容修改的情形,如军事、医学、秘密通信和版权保护等。 相似文献
6.
Fangjun Zhu You Shi Guorong Hu Zhongdong Peng Yanbing Cao Qian Sun Zhichen Xue Yinjia Zhang Ke Du 《Ceramics International》2021,47(3):3070-3078
Titanium and boron are simultaneously introduced into LiNi0.8Co0.1Mn0.1O2 to improve the structural stability and electrochemical performance of the material. X-ray diffraction studies reveal that Ti4+ ion replaces Li+ ion and reduces the cation mixing; B3+ ion enters the tetrahedron of the transition metal layers and enlarges the distance of the [LiO6] layers. The co-doped sample has spherical secondary particles with elongated and enlarged primary particles, in which Ti and B elements distribute uniformly. Electrochemical studies reveal the co-doped sample has improved rate performance (183.1 mAh·g-1 at 1 C and 155.5 mAh·g-1 at 10 C) and cycle stability (capacity retention of 94.7% after 100 cycles at 1 C). EIS and CV disclose that Ti and B co-doping reduces charge transfer impedance and suppresses phase change of LiNi0.8Co0.1Mn0.1O2. 相似文献
8.
Rui ZHAO Weikai LI Tian WANG Ke ZHAN Zheng YANG Ya YAN Bin ZHAO Junhe YANG 《材料科学前沿(英文版)》2020,14(2):188
Effective thermal management of electronic integrated devices with high powder density has become a serious issue, which requires materials with high thermal conductivity (TC). In order to solve the problem of weak bonding between graphite and Cu, a novel Cu/graphite film/Cu sandwich composite (Cu/GF/Cu composite) with ultrahigh TC was fabricated by electro-deposition. The micro-riveting structure was introduced to enhance the bonding strength between graphite film and deposited Cu layers by preparing a rectangular array of micro-holes on the graphite film before electro-deposition. TC and mechanical properties of the composites with different graphite volume fractions and current densities were investigated. The results showed that the TC enhancement generated by the micro-riveting structure for Cu/GF/Cu composites at low graphite content was more effective than that at high graphite content, and the strong texture orientation of deposited Cu resulted in high TC. Under the optimizing preparing condition, the highest in-plane TC reached 824.3 W·m−1·K−1, while the ultimate tensile strength of this composite was about four times higher than that of the graphite film. 相似文献
9.
10.