全文获取类型
收费全文 | 70篇 |
免费 | 6篇 |
国内免费 | 4篇 |
专业分类
化学 | 19篇 |
力学 | 20篇 |
综合类 | 10篇 |
数学 | 10篇 |
物理学 | 21篇 |
出版年
2022年 | 1篇 |
2021年 | 4篇 |
2020年 | 4篇 |
2019年 | 4篇 |
2018年 | 2篇 |
2017年 | 3篇 |
2016年 | 5篇 |
2015年 | 1篇 |
2014年 | 1篇 |
2013年 | 10篇 |
2012年 | 5篇 |
2011年 | 7篇 |
2010年 | 3篇 |
2009年 | 4篇 |
2008年 | 2篇 |
2007年 | 1篇 |
2006年 | 4篇 |
2005年 | 5篇 |
2003年 | 1篇 |
2000年 | 2篇 |
1999年 | 1篇 |
1998年 | 4篇 |
1997年 | 3篇 |
1996年 | 1篇 |
1994年 | 1篇 |
1990年 | 1篇 |
排序方式: 共有80条查询结果,搜索用时 15 毫秒
61.
分析了目前可信计算平台中的设计缺陷,提出了一种简单有效的物理攻击.该攻击能绕过完整性度量对可信计算平台进行攻击.针对这种物理攻击,提出了基于信号完整性分析的TPM(trusted platform module)芯片改进设计方案.在TPM中增加模拟参数度量子模块TPM-APM(TPM-analog parameter measurement),TP-APM子模块通过对可信硬件平台特定网络的模拟参数进行度量与验证,进而保证整个可信硬件平台系统的完整性. 相似文献
62.
Dissimilar materials welded joints provide many advantages in power, automotive, chemical, and spacecraft industries. The weld bead integrity which is determined by process parameters plays a significant role in the welding quality during the fiber laser welding (FLW) of dissimilar materials. In this paper, an optimization method by taking the integrity of the weld bead and weld area into consideration is proposed for FLW of dissimilar materials, the low carbon steel and stainless steel. The relationships between the weld bead integrity and process parameters are developed by the genetic algorithm optimized back propagation neural network (GA-BPNN). The particle swarm optimization (PSO) algorithm is taken for optimizing the predicted outputs from GA-BPNN for the objective. Through the optimization process, the desired weld bead with good integrity and minimum weld area are obtained and the corresponding microstructure and microhardness are excellent. The mechanical properties of the optimized joints are greatly improved compared with that of the un-optimized welded joints. Moreover, the effects of significant factors are analyzed based on the statistical approach and the laser power (LP) is identified as the most significant factor on the weld bead integrity and weld area. The results indicate that the proposed method is effective for improving the reliability and stability of welded joints in the practical production. 相似文献
63.
Arleta Rasmußen 《Optimization》2017,66(12):2107-2124
In the experiment we model all possible consequences from misreporting for both the shareholder and for the manager, since we are interested in patterns in reporting behaviour resulting from different motivations for potential misrepresentation. This allows for examining the stability of the (mis)reporting behaviour in different treatments. Agents are primarily driven by the consequences for themselves rather than by the consequences for the principal, while deciding on misreporting. Participants are willing to sacrifice a small gain for themselves in order to prevent a greater loss for the principal. If agents misreport, they do it in order to generate positive rather than negative consequences for themselves. Reports in favour of the principal, but fruitless or even costly for the agent are very rare. The experiment indicates also that pro-social agents report more truthfully than pro-self agents. 相似文献
64.
基于BP网络,结合GPS接收机自主式完整性检测问题,给出一种用于GPS自主式完整性检测的BP神经网络,通过实验优化了网络参数,经仿真实验表明这种方法是有效可行的。 相似文献
65.
66.
Influence of the material removal mechanisms on hole integrity in ultrasonic machining of structural ceramics 总被引:3,自引:0,他引:3
Micro-chipping via micro-cracks, due to rapid mechanical indentations by abrasive grits, is the fundamental mechanism of material removal during ultrasonic machining (USM) of hard-brittle materials like ceramics and glass. This study aims mainly to investigate the adverse effects of this inherent removal phenomena on the hole integrity such as entrance chipping, wall roughness and subsurface damage. It also presents the material removal mechanism happens in the gap between the tool periphery and the hole wall (called ‘lateral gap’). To do so, experiments were conducted for drilling holes on three advanced structural ceramics, namely, silicon carbide, zirconia, and alumina. Earlier published basic studies on the initiation of different crack modes and their growth characteristics are employed to explain the experimental findings in this USM study. It is realized that the radial and the lateral cracks formed due to adjacent abrasives, which are under the tool face, extends towards radial direction of the hole resulting in entrance chipping. Additionally, the angle penetration and the rolling actions of the abrasives, which are at the periphery of the tool, contribute to the entrance chipping. Later on, in the ‘lateral gap’, the sliding (or abrasion) and the rolling mechanisms by the larger abrasives take part to material removal. However, they unfavorably produce micro-cracks in the radial direction resulting in surface and subsurface damages, which are ultimately responsible for higher wall-surface roughness. Since the size of micro-cracks in brittle materials is grit size dependent according to the earlier studied physics, it is realized that such nature of the hole integrity during USM can only be minimized by employing smaller grit size, but cannot fully be eliminated. 相似文献
67.
给出了计算Jq上n中取m码的全部码字数的公式,以及产生全体码字的生成算法,并分析了其检错能力,为应用这类编码提供了依据. 相似文献
68.
69.
Achiral and chiral liquid chromatographic methods utilizing mass spectrometric detection were developed to investigate the possibility of inversion of configuration at any or all of the chiral centers of the neurokinin-1 (NK-1) receptor antagonist, aprepitant (5-[[2(R)-[1(R)-(3,5-bistrifluoromethyl phenyl)ethoxy]-3(S)-(4-fluorophenyl)morpholin-4-yl]methyl]-2,4-dihydro-[1,2,4]triazol-3-one), in-vivo, following administration of the compound to man. A structure such as aprepitant, that contains three chiral centers, may exist in eight stereochemical forms or, more specifically, as four diastereoisomeric pairs of enantiomers. The four diastereoisomers were separated from each other using a ProntoSil C18 AQ HPLC column (4.6 x 100 mm, 3 microm particles) with a mobile phase composed of acetonitrile--water (47:53, v/v%). Detection was via a single quadrupole mass spectrometer that was connected to the HPLC system via an APCI interface. Analysis of post-dose plasma samples under these conditions indicated that only aprepitant and or its enantiomer were present following oral administration of the drug. Aprepitant and its enantiomer were separated using a Chiralcel OD-H HPLC column with a mobile phase composed of hexane-isopropanol (80:20, v/v%); tandem mass spectrometric detection using an APCI interface was employed. Post-dose plasma samples analyzed using the Chiracel column were found to contain only aprepitant. The results of these experiments confirm that the products of inversion of configuration at any or all of the three chiral centers of aprepitant are not detectable in human plasma samples obtained following the administration of the drug. 相似文献
70.
The surface reactivity of carbon adsorbents (carbon molecular sieves and graphitized carbons) used for analysis of volatile
organic compounds in atmospheric air was studied using 18O as a labelling agent. The carbon adsorbent surface activated in a stream of inert gas at 350°C and then exposed to air is
very active chemically. Apparently peroxide structures are formed. Owing to this activity the integrity of some analytes,
for example dienes and alcohols, among others, is compromised. The active surface can react with the volatile organic compounds
analyzed and even initiate free-radical polymerization. The consequences in analytical practice are discussed. 相似文献