全文获取类型
收费全文 | 148030篇 |
免费 | 2073篇 |
国内免费 | 584篇 |
专业分类
化学 | 83997篇 |
晶体学 | 2261篇 |
力学 | 5615篇 |
综合类 | 5篇 |
数学 | 14258篇 |
物理学 | 44551篇 |
出版年
2021年 | 1069篇 |
2020年 | 1084篇 |
2019年 | 1047篇 |
2016年 | 1953篇 |
2015年 | 1564篇 |
2014年 | 2130篇 |
2013年 | 6164篇 |
2012年 | 5044篇 |
2011年 | 6261篇 |
2010年 | 3903篇 |
2009年 | 3528篇 |
2008年 | 5481篇 |
2007年 | 5336篇 |
2006年 | 5419篇 |
2005年 | 5125篇 |
2004年 | 4479篇 |
2003年 | 4006篇 |
2002年 | 3860篇 |
2001年 | 4013篇 |
2000年 | 3107篇 |
1999年 | 2486篇 |
1998年 | 2086篇 |
1997年 | 2062篇 |
1996年 | 2067篇 |
1995年 | 1951篇 |
1994年 | 1746篇 |
1993年 | 1730篇 |
1992年 | 1907篇 |
1991年 | 1863篇 |
1990年 | 1797篇 |
1989年 | 1775篇 |
1988年 | 1751篇 |
1987年 | 1740篇 |
1986年 | 1638篇 |
1985年 | 2207篇 |
1984年 | 2315篇 |
1983年 | 1926篇 |
1982年 | 2271篇 |
1981年 | 2087篇 |
1980年 | 2106篇 |
1979年 | 2100篇 |
1978年 | 2227篇 |
1977年 | 2129篇 |
1976年 | 2154篇 |
1975年 | 2100篇 |
1974年 | 1935篇 |
1973年 | 2141篇 |
1972年 | 1304篇 |
1968年 | 1055篇 |
1967年 | 1107篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
62.
Ju Yeon Woo Eun Hee Kim Byung Kyu Kim 《Journal of polymer science. Part A, Polymer chemistry》2007,45(23):5590-5596
Doping of conductive fullerene particles to the formulation of conventional holographic polymer dispersed liquid crystal‐induced dual effects of reducing both droplet coalescence and operating voltage. Fullerene induced an induction period which otherwise does not exist, followed by a gradual increase of diffraction efficiency to a saturation value being increased with increasing fullerene content. The increased diffraction efficiency was caused by the decreased droplet coalescence which was due to the hindered migration of LC by the fullerene particles. On the other hand, doped fullerene particles augmented the conductivity of polymer phase and hence the local electrical field imposed on LC droplet, which overcome the threshold for driving and reduced operating voltage and response times. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 5590–5596, 2007 相似文献
63.
64.
65.
Arthur W. Apter 《Mathematical Logic Quarterly》2006,52(5):457-463
We construct models for the level by level equivalence between strong compactness and supercompactness in which for κ the least supercompact cardinal and δ ≤ κ any cardinal which is either a strong cardinal or a measurable limit of strong cardinals, 2δ > δ + and δ is < 2δ supercompact. In these models, the structure of the class of supercompact cardinals can be arbitrary, and the size of the power set of κ can essentially be made as large as desired. This extends and generalizes [5, Theorem 2] and [4, Theorem 4]. We also sketch how our techniques can be used to establish a weak indestructibility result. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
66.
67.
68.
This paper presents the development and laboratory evaluation of a PM10/2.5/1.0 trichotomous sampling inlet that consists of two main parts: a previously designed PM10 size‐selective inlet part and a PM2.5/1.0 two‐stage virtual impactor, which was newly fabricated and attached serially to the PM10 size selective inlet part. Particles are collected in three locations through the trichotomous sampling inlet to provide for not only particle concentration measurements of PM10, PM2.5 and PM1.0, but also those of PM2.5–10 and PM1.0–2.5. 相似文献
69.
70.
For the methylsilsesquioxane film whose optical birefringence is almost zero, it was recently reported that its vertical thermal expansion coefficient (CTE) was approximately one order of magnitude larger than the lateral CTE. Though the birefringence is not an absolute predictor of anisotropic behavior, the discrepancy in both the CTEs was so remarkable that it was essential to investigate whether the anisotropy was intrinsic property or not. If the effect of Poisson's ratio is considered in the calculation of the vertical CTE and when elastic modulus measured by surface acoustic wave spectroscopy is used in the assessment of the lateral CTE, both the CTEs are coincident with each other. Therefore, it can be concluded that the discrepancy in the CTEs can be attributed to a higher in‐plane polymer chain orientation but it can also arise from the misleadingly assumed modulus and Poisson's ratio. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 3109–3120, 2006 相似文献