全文获取类型
收费全文 | 198366篇 |
免费 | 10771篇 |
国内免费 | 5281篇 |
学科分类
工业技术 | 214418篇 |
出版年
2024年 | 356篇 |
2023年 | 1796篇 |
2022年 | 3060篇 |
2021年 | 4561篇 |
2020年 | 3574篇 |
2019年 | 2907篇 |
2018年 | 17257篇 |
2017年 | 16656篇 |
2016年 | 13104篇 |
2015年 | 5365篇 |
2014年 | 6386篇 |
2013年 | 7612篇 |
2012年 | 11000篇 |
2011年 | 17527篇 |
2010年 | 15421篇 |
2009年 | 12284篇 |
2008年 | 13167篇 |
2007年 | 13939篇 |
2006年 | 6513篇 |
2005年 | 6722篇 |
2004年 | 4889篇 |
2003年 | 4295篇 |
2002年 | 3286篇 |
2001年 | 2566篇 |
2000年 | 2849篇 |
1999年 | 2894篇 |
1998年 | 2619篇 |
1997年 | 2052篇 |
1996年 | 1932篇 |
1995年 | 1558篇 |
1994年 | 1294篇 |
1993年 | 946篇 |
1992年 | 728篇 |
1991年 | 597篇 |
1990年 | 433篇 |
1989年 | 404篇 |
1988年 | 337篇 |
1987年 | 176篇 |
1986年 | 156篇 |
1985年 | 107篇 |
1984年 | 93篇 |
1983年 | 59篇 |
1982年 | 61篇 |
1981年 | 55篇 |
1980年 | 49篇 |
1968年 | 45篇 |
1966年 | 44篇 |
1965年 | 45篇 |
1955年 | 63篇 |
1954年 | 68篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
81.
Tao Li Zehui Du Nobumichi Tamura Mao Ye Saikumar Inguva Wei Lu Xierong Zeng Shanming Ke Haitao Huang 《Journal of the European Ceramic Society》2018,38(4):1488-1497
(1-x)Pb(Zn1/3Nb2/3)O3-xPbTiO3 ((1-x)PZN-xPT in short) is one of the most important piezoelectric materials. In this work, we extensively investigated (1-x)PZN-xPT (x = 0.07–0.11) ferroelectric single crystals using in-situ synchrotron μXRD, complemented by TEM and PFM, to correlate microstructures with phase transitions. The results reveal that (i) at 25 °C, the equilibrium state of (1-x)PZN-xPT is a metastable orthorhombic phase for x = 0.07 and 0.08, while it shows coexistence of orthorhombic and tetragonal phases for x = 0.09 and x = 0.11, with all ferroelectric phases accompanied by ferroelastic domains; (ii) upon heating, the phase transformation in x = 0.07 is Orthorhombic → Monoclinic → Tetragonal → Cubic. The coexistence of ferroelectric tetragonal and paraelectric cubic phases was in-situ observed in x = 0.08 above Curie temperature (TC), and (iii) phase transition can be explained by the evolution of the ferroelectric and ferroelastic domains. These results disclose that (1-x)PZN-xPT are in an unstable regime, which is possible factor for its anomalous dielectric response and high piezoelectric coefficient. 相似文献
82.
In this paper, we consider the classical finite mixture model, which is an effective tool for modeling lifetime distributions for random samples from heterogeneous populations. We discuss new results on stochastic comparison for two finite mixtures when each of them is drawn from one of the following semiparametric families, i.e., proportional hazards, accelerated lifetime and proportional reversed hazards. 相似文献
83.
84.
85.
Variations of Incomplete Open Cubes is the major project by the twentieth-century conceptual artist Sol LeWitt. In this paper we interpret the enumerative component of the project as embeddings of graphs. This formulation permits use of an algorithm to check the completeness of the list of the structures produced by the artist. Our conclusion is that the artist found the correct number of structures (that is, 122), but that his list contains a mistake in the presentation of a pair of incomplete cubes, a discovery that appears not to have been noted before. 相似文献
86.
87.
88.
Multifunctional 3D Patternable Drug‐Embedded Nanocarrier‐Based Interfaces to Enhance Signal Recording and Reduce Neuron Degeneration in Neural Implantation 下载免费PDF全文
89.
90.