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991.
滑动模式对超高分子量聚乙烯摩擦磨损行为的影响 总被引:2,自引:1,他引:2
在自行研制的髋关节模拟试验机上,以交叉滑动及单向滑动2种方式对比考察了蒸馏水润滑条件下超高分子量聚乙烯(UHMWPE)的摩擦磨损性能,采用扫描电子显微镜观察分析了UHMWPE的磨损表面形貌并探讨其磨损机理.结果表明:在相同载荷条件下,UHMWPE在交叉滑动方式下的磨损率明显高于单向滑动方式;在交叉滑动方式下,UHMWPE的主要磨损机制为磨粒磨损、粘着磨损及塑性变形引起的表层剥落,而在单向滑动下其磨损形式主要为磨粒磨损伴随着少量的疲劳剥片;不同滑动方式所导致的磨损机理差异是造成UHMWPE磨损性能变化的主要原因.与其它试验方式相比,在髋关节模拟试验机上所得出的试验数据更接近临床观测结果. 相似文献
992.
泡沫铝填充薄壁圆管的三点弯曲实验的数值模拟 总被引:2,自引:0,他引:2
泡沫金属填充薄壁结构的应用日趋广泛,建立合理的数值计算模型对结构设计和工程应用非常重要.该文通过对泡沫铝填充薄壁铝合金圆管的三点弯曲实验的数值模拟,研究了它的力学行为.采用ABAQUS软件,建立了空管和泡沫铝全填充管的有限元模型,并对这两种结构在三点弯曲下的力学行为进行了数值模拟,所得结果与实验结果符合得较好.通过数值模拟分析了结构的承载机理和不同压头直径对结构承载能力的影响.此外,还研究了泡沫铝部分填充圆管的三点弯曲行为,分析了不同填充长度对结构承载能力的影响. 相似文献
993.
994.
灰色系统模型在结构损伤识别中的应用 总被引:1,自引:0,他引:1
开发结构健康监测系统是结构损伤识别的一个重要课题。由于建筑结构具有很多不确定因素,通过模态分析识别结构损伤的精度很难保证。本文提出一种灰色系统模型应用于结构损伤识别的方法。建立频率变化率和刚度变化的灰色系统模型,把一阶单变量的灰色模型(M(1,1))作为频率变化率和刚度变化之间的系统,通过一阶单变量的灰色模型(M(1,1))预测来体现结构动力指纹的整体功能,确定频率变化率和刚度变化之间的关系变量。为了验证理论,对多种工况进行了框架结构模型的振动试验并对结果进行了分析。试验结果表明:对于层间剪切结构,通过测量结构频率变化,建立的灰色系统模型可以较准确地确定结构的损伤位置和损伤程度,并使识别精度得到有效提高。 相似文献
995.
A nonparametric structural damage detection methodology based on neural networks method is presented for health monitoring
of structure-unknown systems. In this approach appropriate neural networks are trained by use of the modal test data from
a ‘healthy’ structure. The trained networks which are subsequently fed with vibration measurements from the same structure
in different stages have the capability of recognizing the location and the content of structural damage and thereby can monitor
the health of the structure. A modified back-propagation neural network is proposed to solve the two practical problems encountered
by the traditional back-propagation method, i.e., slow learning progress and convergence to a false local minimum. Various
training algorithms, types of the input layer and numbers of the nodes in the input layer are considered. Numerical example
results from a 5-degree-of-freedom spring-mass structure and analyses on the experimental data of an actual 5-storey-steel-frame
demonstrate that neural-networks-based method is a robust procedure and a practical tool for the detection of structural damage,
and that the modified back-propagation algorithm could improve the computational efficiency as well as the accuracy of detection
Project supported by the National Natural Science Foundation of China (No. 59908003) and the Natural Science Foundation of
Hubei Province (No. 99J035). 相似文献
996.
光纤陀螺可视化测试系统设计与实现 总被引:1,自引:0,他引:1
叙述了光纤陀螺可视化测试系统的设计方案和实现功能。该系统通过VC++6.0中方便简洁的串口通信控件MSComm来实现光纤陀螺的数据采集,并使用技巧的数据存储方法,存储后的数据通过MATLAB7.0开发的数据处理程序进行处理,所有操作均采用模块化设计和可视化方法,方便和简化了复杂的测试过程。实验结果表明整个测试系统具有准确性、方便性等优点。 相似文献
997.
On-line pseudo-dynamic network testing on base-isolated bridges using Internet and wireless Internet 总被引:2,自引:0,他引:2
D -U. Park C -B. Yun J -W. Lee K. Nagata E. Watanabe K. Sugiura 《Experimental Mechanics》2005,45(4):331-343
In this paper we present the results of the online pseudo-dynamic network testing using the Internet that were jointly conducted
by several institutions in Korea and Japan. Example studies were performed on base-isolated bridges with four continous spans.
Test facilities located at several institutions were interactively used to test the non-linear behaviors of the base isolators.
At first, a series of international network tests was carried out between Japan and Korea, and the performance of two system
configurations with different data communication schemes was compared. Then, network tests were repeated on a similar bridge
structure between two institutions in Korea, and the overall performance was discussed. A web-based Java monitoring system
was developed for checking the partners' testing conditions and for sharing the test results with the authorized observers.
Wireless Internet technology using mobile phones was also investigated. The results indicate that the time to execute a single
step varies widely, depending on the data communication/sharing schemes and the testing hardware, e.g., 0.2–15 s for data
communication and 1–10 s for execution of the pseudo-dynamic tests for each time-step. The time required additionally for
data communication in the on-line network testing is judged as reasonable in comparison with the time for the pseudo-dynamic
test. The results also show that the wireless communication is very attractive for on-line network testing, owing to the mobility
and Internet security. 相似文献
998.
导出了纤维金属胶接层板双面裂纹搭接剪切(DCLS)试样分层尺寸和柔度之间的线性关系式,提出了DCLS试样分层尺寸的柔度测量法,并与用光测法测得的分层尺寸进行了对比。结果表明,用柔度法测定DCLS试样的分层尺寸,不仅测量结果准确,而且简单易行,避免了光测法的诸多麻烦和精度低的缺点。 相似文献
999.
We present a procedure for measuring the dynamic fracture-initiation toughness of materials. The method is based on three-point
bending tests at high loading rates, performed in an experimental device which is a modification of the classical split Hopkinson
pressure bar. Coupled with the loading device, a high-speed photography system was used to measure the crack mouth opening
displacement (CMOD) directly on the specimen. The stress intensity factor was calculated by three different simplified methods
and the time to fracture was obtained from an appropriate specimen instrumentation. To evaluate the results derived from the
simplified methods, a two-dimensional full-numerical analysis of the dynamic bending fracture test was made. The model includes
the specimen, the input bar, the impacting projectile and the supporting device and takes into account the possible loss of
contact during the experiment between the input bar and the specimen and between the specimen and its supports. From the tests
and numerical results, it can be concluded that the CMOD procedure, together with the knowledge of the time to fracture determined
using crack gages, seems to be the best method for measuring dynamic fracture-initiation toughness. 相似文献
1000.