全文获取类型
收费全文 | 320篇 |
免费 | 9篇 |
国内免费 | 5篇 |
专业分类
化学 | 177篇 |
晶体学 | 4篇 |
力学 | 5篇 |
数学 | 60篇 |
物理学 | 88篇 |
出版年
2024年 | 1篇 |
2023年 | 5篇 |
2022年 | 2篇 |
2021年 | 10篇 |
2020年 | 10篇 |
2019年 | 7篇 |
2018年 | 6篇 |
2017年 | 5篇 |
2016年 | 4篇 |
2015年 | 11篇 |
2014年 | 11篇 |
2013年 | 24篇 |
2012年 | 19篇 |
2011年 | 11篇 |
2010年 | 13篇 |
2009年 | 9篇 |
2008年 | 15篇 |
2007年 | 23篇 |
2006年 | 9篇 |
2005年 | 17篇 |
2004年 | 17篇 |
2003年 | 12篇 |
2002年 | 17篇 |
2001年 | 4篇 |
2000年 | 11篇 |
1999年 | 6篇 |
1998年 | 3篇 |
1997年 | 4篇 |
1996年 | 9篇 |
1995年 | 10篇 |
1994年 | 6篇 |
1993年 | 4篇 |
1992年 | 7篇 |
1991年 | 3篇 |
1990年 | 2篇 |
1987年 | 3篇 |
1986年 | 1篇 |
1980年 | 1篇 |
1887年 | 1篇 |
1886年 | 1篇 |
排序方式: 共有334条查询结果,搜索用时 307 毫秒
91.
C. Y. Lee D. E. Lee C. K. Jeong Y. K. Hong J. H. Shim J. Joo M. S. Kim J. Y. Lee S. H. Jeong S. W. Byun D. S. Zang H. G. Yang 《先进技术聚合物》2002,13(8):577-583
Electromagnetic interference (EMI) shielding materials of complex type of conductive polypyrrole (PPy) as an intrinsically conducting polymer and silver‐palladium (AgPd) metal compound coated on woven or non‐woven fabrics are synthesized. From dc conductivity and SEM photographs of PPy/fabric complexes, we discuss charge transport mechanism and the homogeneity of coating on the fabrics. The EMI shielding efficiency of PPy/fabric and AgPd/fabric complexes is in the range of 8 ~ 80 dB depending on the conductivity and the additional Ag vacuum evaporation. The highest EMI shielding efficiency of PPy/fabric complexes vacuum‐evaporated by Ag is ~80 dB, indicating potential materials for military uses. We propose that PPy/fabrics are excellent RF and microwave absorber because of the relatively high absorbance and low reflectance of the materials. Copyright © 2002 John Wiley & Sons, Ltd. 相似文献
92.
It is important to define a standard method to store basic sensor information, such as the type and the structure of sensors for an electronic tongue system and there is no such method defined in the IEEE 1451.4 transducer electronic data sheet (TEDS) so far. The major challenge is to choose a suitable standard template that can be used with sensors for electronic tongues. However, the standard templates provide an imprecise specification when used with sensing devices for electronic tongues. In this paper, we present definitions of the basic TEDS of IEEE 1451.4 for sensors for an electronic tongue system and propose a new template TEDS for IEEE 1451.4 for potentiometric devices. 相似文献
93.
We study optimal W2,p-regularity for fourth-order parabolic equations with discontinuous coefficients in general domains. We obtain the global W2,p-regularity for each 1<p<∞ under the assumption that the coefficients have suitably small BMO semi-norm of weak type and the boundary of the domain is δ-Reifenberg flat. The situation of our main theorem arises when the conductivity on fractals is controlled by a random variable in the time direction. 相似文献
94.
In this paper we define time dependent parabolic Reifenberg domains and study Lp estimates for weak solutions of uniformly parabolic equations in divergence form on these domains. The basic assumption is that the principal coefficients are of parabolic BMO space with small parabolic BMO seminorms. It is shown that Lp estimates hold for time dependent parabolic δ-Reifenberg domains. 相似文献
95.
We study the inhomogeneous conormal derivative problem for thedivergence form elliptic equation, assuming that the principalcoefficients belong to the BMO space with small BMO semi-normsand that the boundary is -Reifenberg flat. These conditionsfor the W1, p-theory not only weaken the requirements on thecoefficients but also lead to a more general geometric conditionon the domain. In fact, the Reifenberg flatness is the minimalregularity condition for the W1, p-theory. 2000 MathematicsSubject Classification 35R05 (primary), 35J15 (secondary). 相似文献
96.
Y. Byun Y. Lee J. Park J. S. Ryu 《Proceedings of the American Mathematical Society》2001,129(4):1161-1168
We show that, on an oriented Riemannian 4-manifold, existence of a non-zero parallel spinor with respect to a spin structure implies that the underlying smooth manifold admits a Kähler structure. A similar but weaker condition is obtained for the 4-manifold to admit a symplectic structure. We also show that the structure in which the non-zero parallel spinor lives is equivalent to the canonical spin structure associated to the Kähler structure.
97.
Dr. Yearin Byun Lilia S. Xie Patrick Fritz Timur Ashirov Prof. Mircea Dincă Prof. Ali Coskun 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(35):15278-15282
Dimensionality plays an important role in the charge transport properties of organic semiconductors. Although three-dimensional semiconductors, such as Si, are common in inorganic materials, imparting electrical conductivity to covalent three-dimensional organic polymers is challenging. Now, the synthesis of a three-dimensional π-conjugated porous organic polymer (3D p-POP) using catalyst-free Diels–Alder cycloaddition polymerization followed by acid-promoted aromatization is presented. With a surface area of 801 m2 g−1, full conjugation throughout the carbon backbone, and an electrical conductivity of 6(2)×10−4 S cm−1 upon treatment with I2 vapor, the 3D p-POP is the first member of a new class of permanently porous 3D organic semiconductors. 相似文献
98.
In this paper, the oscillation of the meniscus in an electrospray with AC voltage is semi-analytically investigated. The electric field is achieved using the charge simulation method and the mutual interaction between the electric field and hydrodynamics is iteratively explored to investigate the oscillation. After determining the static meniscus shape on a nozzle, the meniscus oscillation is simulated under sinusoidal AC voltage. The semi-analytic simulation can offer the oscillating meniscus shapes and contours of the electric field outside the meniscus according to the applied frequency. Furthermore, the velocity profile of the liquid inside the meniscus is achieved. 相似文献
99.
100.
Song Ju Park Jung Min Cho Won‐Bae Byun Jong‐Cheol Lee Won Suk Shin In‐Nam Kang Sang‐Jin Moon Sang Kyu Lee 《Journal of polymer science. Part A, Polymer chemistry》2011,49(20):4416-4424
Polymer solar cells (PSCs) were fabricated using a ternary blend film consisting two conjugated polymers and a soluble fullerene derivative as the donor and acceptor materials, respectively. And, to compare ternary blend system, the single‐component copolymers consisting of the repeating units of each of the copolymers, used in ternary blend solar cells, were designed and synthesized for use as the electron donor materials in binary blend solar cells. We systematically investigated the field‐effect carrier mobilities and the optical, electrochemical, and photovoltaic properties of the copolymers. Under optimized conditions, the binary blend polymer systems showed power conversion efficiencies (PCEs) for the PSCs in the range 3.87–4.16% under AM 1.5 illumination (100 mW cm?2). All polymers exhibited similar PCEs that did not depend on the ratio of repeating units. The binary blend solar cell containing a single‐component copolymer as the electron donor material performed better than the ternary blend solar cell in this work. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011 相似文献