全文获取类型
收费全文 | 798篇 |
免费 | 99篇 |
国内免费 | 70篇 |
专业分类
化学 | 228篇 |
力学 | 49篇 |
综合类 | 10篇 |
数学 | 44篇 |
物理学 | 140篇 |
综合类 | 496篇 |
出版年
2024年 | 2篇 |
2023年 | 1篇 |
2022年 | 13篇 |
2021年 | 28篇 |
2020年 | 30篇 |
2019年 | 20篇 |
2018年 | 16篇 |
2017年 | 13篇 |
2016年 | 31篇 |
2015年 | 42篇 |
2014年 | 57篇 |
2013年 | 61篇 |
2012年 | 47篇 |
2011年 | 52篇 |
2010年 | 46篇 |
2009年 | 48篇 |
2008年 | 45篇 |
2007年 | 56篇 |
2006年 | 41篇 |
2005年 | 49篇 |
2004年 | 34篇 |
2003年 | 29篇 |
2002年 | 25篇 |
2001年 | 24篇 |
2000年 | 28篇 |
1999年 | 17篇 |
1998年 | 17篇 |
1997年 | 17篇 |
1996年 | 15篇 |
1995年 | 7篇 |
1994年 | 8篇 |
1993年 | 5篇 |
1992年 | 5篇 |
1991年 | 4篇 |
1990年 | 4篇 |
1989年 | 3篇 |
1988年 | 4篇 |
1987年 | 4篇 |
1986年 | 8篇 |
1985年 | 3篇 |
1982年 | 1篇 |
1980年 | 1篇 |
1979年 | 2篇 |
1970年 | 1篇 |
1969年 | 1篇 |
1968年 | 1篇 |
1936年 | 1篇 |
排序方式: 共有967条查询结果,搜索用时 31 毫秒
1.
王珏 《西安联合大学学报》2008,11(1):94-96
近期,居民消费价格指数(CPI)呈线性增长态势,形成通胀压力.经过建立数学模型测定,以及定性分析对定量分析结果的修正,可以预见,CPI增幅将会突破5%,且今后一段时期内,CPI仍会处在增幅5%以上的高位波动,通胀压力仍然存在,但CPI的上升空间有限. 相似文献
2.
Jue Lu Chang K. Hong Richard P. Wool 《Journal of Polymer Science.Polymer Physics》2004,42(8):1441-1450
Some discovery work was done on the synthesis of clay nanocomposites based on renewable plant oils. Functionalized triglycerides, such as acrylated epoxidized soybean oil, maleinized acrylated epoxidized soybean oil, and soybean oil pentaerythritol maleates, combined with styrene were used as the polymer matrix. The miscibility of these monomers and clay organomodifier was assessed by solubility parameters. The formation of nanocomposites was confirmed by both X‐ray data and transmission electron microscopy. The morphology showed a mix of intercalated and partially exfoliated sheets. The flexural modulus increased 30% at only 4 vol % clay content, but there was no significant effect on flexural strength, glass‐transition temperature, and thermal stability. Property enhancement was related to the degree of exfoliation that depends on both the polarity and flexibility of the monomers. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 1441–1450, 2004 相似文献
3.
四溴双酚A锑铝双金属化合物的合成及其阻燃性能 总被引:1,自引:0,他引:1
以四溴双酚A(TBA)合成了在水和空气中稳定的四溴双酚A合锑铝双金属化合物(TBASA).通过IR、1HNMR和元素分析予以表征,并研究了其对聚乙烯(PE)和聚环氧乙烷(PEO)的阻燃性能.结果表明,这种分子中含有溴、锑和铝的化合物,对聚乙烯和聚环氧乙烷等高聚物材料有高的阻燃性能与消烟效果. 相似文献
4.
5.
This paper presents the applications of digital image correlation technique to the mesoscopic damage and fracture study of
some granular based composite materials including steelfiber reinforced concrete, sandstone and crystal-polymer composite.
The deformation fields of the composite materials resulted from stress localization were obtained by the correlation computation
of the surface images with loading steps and thus the related damage prediction and fracture parameters were evaluated. The
correlation searching could be performed either directly based on the gray levels of the digital images or from the wavelet
transform (WT) coefficients of the transform spectrum. The latter was developed by the authors and showed higher resolution
and sensitivity to the singularity detection. Because the displacement components came from the rough surfaces of the composite
materials without any coats of gratings or fringes of optical interferometry, both surface profiles and the deformation fields
of the composites were visualized which was helpful to compare each other to analyze the damage of those heterogeneous materials.
The project supported by the National Natural Science Foundation of China (10125211 and 10072002), the Scientific Committee
of Yunnan Province for the Program of Steel Fiber Reinforced Concrete, and the Institute of Chemical Materials, CAEP at Mianyang 相似文献
6.
7.
针对巨型水压机多层垫板组力学行为的多维非线性特征,本文应用作者开发的多体接触有限元程序,分析了300MN水压机垫板组力学行为规律,揭示了垫板组加载方式为几何空间状态与力学行为的相关性,说明了垫板组异常变形机制,提出了垫板组设计和使用的几点准则。 相似文献
8.
9.
10.
Jun Shen Tianhe Yang Qinyuan Zhang Jue Wang Qinyao Zhang 《Journal of Sol-Gel Science and Technology》2003,26(1-3):1029-1032
In GaAs based infrared detectors, a considerable part of the incident light will be reflected at the surface, thus it decreases the detectors sensitivity considerably. In this paper, a TiO2 nanoporous coating was prepared successfully on the GaAs substrate by sol-gel method. The optical parameters of the coating were also controlled successfully. It was proved that the coating could greatly improve the transmittance of the incident light, which agrees with the theoretical results quite well. In the 2.5–6.0 m waveband, the maximum transmittance of GaAs substrate is 56%, while the transmittance of the GaAs substrate coated with a nanostructured TiO2 coating is about 94%. 相似文献