全文获取类型
收费全文 | 263篇 |
免费 | 43篇 |
国内免费 | 32篇 |
专业分类
化学 | 73篇 |
力学 | 68篇 |
综合类 | 21篇 |
数学 | 54篇 |
物理学 | 122篇 |
出版年
2024年 | 1篇 |
2023年 | 6篇 |
2022年 | 17篇 |
2021年 | 24篇 |
2020年 | 10篇 |
2019年 | 4篇 |
2018年 | 8篇 |
2017年 | 16篇 |
2016年 | 21篇 |
2015年 | 30篇 |
2014年 | 14篇 |
2013年 | 19篇 |
2012年 | 12篇 |
2011年 | 9篇 |
2010年 | 8篇 |
2009年 | 9篇 |
2008年 | 12篇 |
2007年 | 11篇 |
2006年 | 11篇 |
2005年 | 9篇 |
2004年 | 5篇 |
2003年 | 11篇 |
2002年 | 9篇 |
2001年 | 7篇 |
2000年 | 10篇 |
1999年 | 13篇 |
1998年 | 7篇 |
1997年 | 6篇 |
1996年 | 7篇 |
1995年 | 1篇 |
1994年 | 3篇 |
1993年 | 1篇 |
1992年 | 2篇 |
1990年 | 1篇 |
1988年 | 1篇 |
1987年 | 1篇 |
1986年 | 1篇 |
1979年 | 1篇 |
排序方式: 共有338条查询结果,搜索用时 15 毫秒
91.
为适应自主驾驶车辆的高精度、高频率与高可靠性的导航要求,提出了一种机器视觉/数字地图/CP-DGPS共同辅助SINS的智能车辆组合导航方法,建立了组合导航系统的滤波模型。该滤波模型的量测信息不仅包括GPS与SINS形成的位置与姿态观测信息,还包括机器视觉/数字地图/SINS形成的横向偏差观测信息。通过对SINS的多重冗余辅助,使得导航系统具备容错能力。仿真结果表明,该组合导航系统能为智能车辆提供其空间位置、速度、加速度与姿态角等众多导航信息,并具有100Hz的高频输出、厘米级的导航精度和容错性能,当GPS较长时间中断时,通过SINS/视觉/数字地图的组合仍能为智能车辆提供可靠的导航数据。 相似文献
92.
加速度计智能化检测系统设计研究 总被引:2,自引:0,他引:2
本文对部队现役装备及测试体制进行了分析研究,设计了加速度计(PI-GA)智能化检测系统,并在系统中加入了故障自诊断功能。 相似文献
93.
94.
SELF-CORRECTED PID VIBRATION CONTROL BASED ON DUAL-FREEDOM DUAL-DRIVE INTELLIGENT CANTILEVER BEAM 1)
随着科技不断进步,智能结构的振动控制在航天航空、机械制造、车辆与船舶等领域得到了广泛应用。由于多输入多输出存在多样性和复杂性,严重威胁系统稳定性。为了解决这一问题,针对两输入单输出的双驱动智能悬臂梁系统提出一种自适应控制策略,首先基于压电线性本构方程,应用假设模态方法建立双驱动智能悬臂梁的力学模型,得到了基于闭环控制系统的状态方程,同时利用递推最小二乘法在线辨识系统参数设计比例积分微分(proportional--integral--derivative, PID)控制器实现自校正PID控制。通过数值仿真对比在有无PID 控制下两输入单输出双驱动智能悬臂梁系统的振动情况,分析自校正PID 控制的控制效果。通过实验验证自校正PID 控制对双输入单输出的双驱动智能悬臂梁系统的控制效果;再设置两组不同的单输入单输出自校正PID控制实验作对比。结果表明:自校正PID 控制方法可以较为有效地抑制智能悬臂梁的自由振动,相比单输入单输出的两组,两输入单输出自校正PID控制的效果更为明显和有效。 相似文献
95.
96.
97.
Instrumental test of food quality using perception sensors instead of human panel test is attracting massive attention recently. A novel cross-perception multi-sensors data fusion imitating multiple mammal perception was proposed for the instrumental test in this work. First, three mimic sensors of electronic eye, electronic nose and electronic tongue were used in sequence for data acquisition of rice wine samples. Then all data from the three different sensors were preprocessed and merged. Next, three cross-perception variables i.e., color, aroma and taste, were constructed using principal components analysis (PCA) and multiple linear regression (MLR) which were used as the input of models. MLR, back-propagation artificial neural network (BPANN) and support vector machine (SVM) were comparatively used for modeling, and the instrumental test was achieved for the comprehensive quality of samples. Results showed the proposed cross-perception multi-sensors data fusion presented obvious superiority to the traditional data fusion methodologies, also achieved a high correlation coefficient (>90%) with the human panel test results. This work demonstrated that the instrumental test based on the cross-perception multi-sensors data fusion can actually mimic the human test behavior, therefore is of great significance to ensure the quality of products and decrease the loss of the manufacturers. 相似文献
98.
Jun Seok Kim Hee-Sung Ahn Soo Min Cho Ji Eun Lee YoungSoo Kim Cheolju Lee 《Analytica chimica acta》2014
Amyloid-β (Aβ) in human plasma was detected and quantified by an antibody-free method, selected reaction monitoring mass spectrometry (SRM-MS) in the current study. Due to its low abundance, SRM-based quantification in 10 μL plasma was a challenge. Prior to SRM analysis, human plasma proteins as a whole were digested by trypsin and high pH reversed-phase liquid chromatography (RPLC) was used to fractionate the tryptic digests and to collect peptides, Aβ1–5, Aβ6–16, Aβ17–28 and Aβ29–40(42) of either Aβ1–40 or Aβ1–42. Among those peptides, Aβ17–28 was selected as a surrogate to measure the total Aβ level. Human plasma samples obtained from triplicate sample preparations were analyzed, obtaining 4.20 ng mL−1 with a CV of 25.3%. Triplicate measurements for each sample preparation showed CV of <5%. Limit of quantification was obtained as 132 pM, which corresponded to 570 pg mL−1 of Aβ1–40. Until now, most quantitative measurements of Aβ in plasma or cerebrospinal fluid have required antibody-based immunoassays. Since quantification of Aβ by immunoassays is highly dependent on the extent of epitope exposure due to aggregation or plasma protein binding, it is difficult to accurately measure the actual concentration of Aβ in plasma. Our diagnostic method based on SRM using a surrogate peptide of Aβ is promising in that actual amounts of total Aβ can be measured regardless of the conformational status of the biomarker. 相似文献
99.
100.