全文获取类型
收费全文 | 6894篇 |
免费 | 398篇 |
国内免费 | 680篇 |
专业分类
化学 | 1601篇 |
晶体学 | 8篇 |
力学 | 55篇 |
综合类 | 87篇 |
数学 | 2631篇 |
物理学 | 458篇 |
综合类 | 3132篇 |
出版年
2024年 | 8篇 |
2023年 | 62篇 |
2022年 | 113篇 |
2021年 | 150篇 |
2020年 | 127篇 |
2019年 | 148篇 |
2018年 | 164篇 |
2017年 | 174篇 |
2016年 | 182篇 |
2015年 | 142篇 |
2014年 | 319篇 |
2013年 | 520篇 |
2012年 | 312篇 |
2011年 | 386篇 |
2010年 | 321篇 |
2009年 | 385篇 |
2008年 | 368篇 |
2007年 | 474篇 |
2006年 | 429篇 |
2005年 | 415篇 |
2004年 | 360篇 |
2003年 | 332篇 |
2002年 | 299篇 |
2001年 | 243篇 |
2000年 | 222篇 |
1999年 | 190篇 |
1998年 | 190篇 |
1997年 | 144篇 |
1996年 | 149篇 |
1995年 | 121篇 |
1994年 | 115篇 |
1993年 | 74篇 |
1992年 | 68篇 |
1991年 | 42篇 |
1990年 | 41篇 |
1989年 | 46篇 |
1988年 | 35篇 |
1987年 | 28篇 |
1986年 | 16篇 |
1985年 | 21篇 |
1984年 | 10篇 |
1983年 | 2篇 |
1982年 | 3篇 |
1981年 | 3篇 |
1980年 | 7篇 |
1979年 | 3篇 |
1978年 | 2篇 |
1976年 | 3篇 |
1959年 | 1篇 |
1936年 | 1篇 |
排序方式: 共有7972条查询结果,搜索用时 890 毫秒
1.
2.
Tianyu Gong Longhai Guo Jun Ye Lifan He Teng Qiu Xiaoyu Li 《Journal of polymer science. Part A, Polymer chemistry》2021,59(16):1807-1820
The implementation of covalent adaptable networks (CANs) in general resin system is becoming attractive. In this work, we propose a simple post-curing strategy based on the core-shell structured acrylate latex for the achievement on both the improved general performance and the CANs characteristics in latex films. The building to the CANs was relied on the introduction of 4,4′-diaminophenyl disulfide as the curing agent, which cured the acetoacetoxy decorated shell polymer through the ketoamine reaction. The metathesis reaction of aromatic disulfides in the crosslinking segments enabled the thermally induced dynamic behavior of the network as revealed in the stress relaxation tests by comparison with other diamine crosslinking agents without the incorporation of disulfide. The synergism of the dynamic crosslinking of the shell polymer and static crosslinking in the core polymer contributed to the improved mechanical strength (15 MPa, strain% = 250%) and the suppressed water adsorption (~1% in 24 h of soaking) of the latex film, which exhibited above 90% of recovery in both strength and strain from a cut-off film damage within 1 h at 80°C. Moreover, the cured latex film could be recycled, and 75% of the mechanical performance was regained after three fragmentation-hot-pressing cycles. These, in addition with the feasible and environmental friendly characteristics, suggest a sustainable paradigm toward the smart thermosetting latex polymers. 相似文献
3.
咸伟志 《重庆工商大学学报(自然科学版)》2015,32(9):33-38
柯西不等式是高等数学中的重要不等式,它在解析几何、数学分析与高等代数这3门数学专业主干基础课程中均有渗透.从这3门课程的角度,分别给出柯西不等式的不同形式和证明过程,并简要地阐述它们的联系,最后做出小结. 相似文献
4.
〈I〉型三角剖分下非张量积连续小波基的构造 总被引:1,自引:0,他引:1
多维非张量积小波是近年小波研究领域中的热点问题之一 ,它们与多维张量积小波相比具有更多的优势 .关于高维张量积、非张量积小波 ,目前已有一些很好的工作 (见文[2 ] [3 ] [4 ] ) ,但关于样条小波 ,还有许多问题有待于研究 .本文针对〈I〉型三角剖分下的二维线性元空间 ,讨论其具有紧支集和对称性的半正交样条小波基 .给定 x1 x2 平面上的〈I〉型三角剖分 (图 1 ( a)所示 ) ,记 j=( j1 ,j2 ) ,| j| =j1 + j2 ,πm= { 0≤ |j|≤ mCj1j2 xj11 xj22 ,Cj1,j2 是任意实数 }为次数不超过 m的代数多项式全体 .引入剖分尺度为 1的线性元空间 V0… 相似文献
5.
6.
A.Y. El-Etre 《Applied Surface Science》2006,252(24):8521-8525
The inhibitive effect of the extract of khillah (Ammi visnaga) seeds, on the corrosion of SX 316 steel in HCl solution was determined using weight loss measurements as well as potentiostatic technique. It was found that the presence of the extract reduces markedly the corrosion rate of steel in the acid solution. The inhibition efficiency increases as the extract concentration is increased. The inhibitive effect of khillah extract was discussed on the basis of adsorption of its components on the metal surface. Negative values were calculated for the energy of adsorption indicating the spontaneity of the adsorption process. The formation of insoluble complexes as a result of interaction between iron cations and khellin, which present in the extract, was also discussed. 相似文献
7.
产品数据管理(PDM)在制造业中的应用与发展 总被引:2,自引:0,他引:2
在计算机技术快速发展的今天,许多企业的软件使用者和领导者开始体会到新技术带来的效益和进一步发展的必要性,认为到企业信息化的基础是产品数据管理(PDM)从PDM的产生、特点、结构、应用和发展等方面,详细地介绍了PDM的功能及其地位,以及在实施中要注意的事项。 相似文献
8.
9.
10.
Relying on reliability growth testing to improve system designis neither usually effective nor efficient. Instead it is importantto design in reliability. This requires models to estimate reliabilitygrowth in the design that can be used to assess whether goalreliability will be achieved within the target timescale forthe design process. Many models have been developed for analysisof reliability growth on test, but there has been much lessattention given to reliability growth in design. This paperdescribes and compares two models: one motivated by the practicalengineering process; the other by extending the reasoning ofstatistical reliability growth modelling. Both models are referencedin the recently revised edition of international standard IEC61164. However, there has been no reported evaluation of theirproperties. Therefore, this paper explores the commonalitiesand differences between these models through an assessment oftheir logic and their application to an industrial example.Recommendations are given for the use of reliability growthmodels to aid management of the design process and to informproduct development. 相似文献