全文获取类型
收费全文 | 84077篇 |
免费 | 501篇 |
国内免费 | 406篇 |
专业分类
化学 | 28915篇 |
晶体学 | 845篇 |
力学 | 6812篇 |
数学 | 32257篇 |
物理学 | 16155篇 |
出版年
2022年 | 56篇 |
2021年 | 65篇 |
2020年 | 89篇 |
2019年 | 110篇 |
2018年 | 10474篇 |
2017年 | 10299篇 |
2016年 | 6164篇 |
2015年 | 941篇 |
2014年 | 429篇 |
2013年 | 606篇 |
2012年 | 4102篇 |
2011年 | 10885篇 |
2010年 | 5830篇 |
2009年 | 6278篇 |
2008年 | 6974篇 |
2007年 | 9135篇 |
2006年 | 665篇 |
2005年 | 1690篇 |
2004年 | 1901篇 |
2003年 | 2256篇 |
2002年 | 1300篇 |
2001年 | 364篇 |
2000年 | 374篇 |
1999年 | 229篇 |
1998年 | 270篇 |
1997年 | 226篇 |
1996年 | 282篇 |
1995年 | 185篇 |
1994年 | 131篇 |
1993年 | 150篇 |
1992年 | 94篇 |
1991年 | 105篇 |
1990年 | 78篇 |
1989年 | 88篇 |
1988年 | 94篇 |
1987年 | 98篇 |
1986年 | 109篇 |
1985年 | 119篇 |
1984年 | 104篇 |
1983年 | 68篇 |
1982年 | 101篇 |
1981年 | 97篇 |
1980年 | 105篇 |
1979年 | 93篇 |
1978年 | 74篇 |
1977年 | 48篇 |
1976年 | 51篇 |
1973年 | 51篇 |
1914年 | 45篇 |
1909年 | 41篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
901.
902.
903.
904.
905.
906.
907.
Yuhei Horio Md. Mijanur Rahman Yurei Imai Yoshihiro Hishikawa Takashi Minemoto 《Current Applied Physics》2017,17(10):1341-1346
The output energy of photovoltaic (PV) modules is influenced by the spectral irradiance distribution of the solar spectrum under outdoor conditions. To rate the precise output energy of PV modules, the correction of short circuit current (ISC) based on actual environmental conditions is needed, because ISC significantly depends on the shape of the spectral irradiance distribution. The average photon energy (APE) is a zero-dimensional index for spectral irradiance distribution, and APE value uniquely describes the shape of a solar spectrum. Thus, APE has an impact on ISC of PV modules. In this contribution, the relationship between APE coefficient and ISC of the multi-crystalline silicon, single-crystalline silicon, heterojunction intrinsic thin-layer, back contact, copper indium selenide and cadmium telluride PV modules has explored. It is revealed that APE value changes the ISC of PV modules which appeared to have immense possibilities of ISC correction using APE coefficient. This new approach can be very effective for precise rating the output energy of PV modules under actual outdoor conditions. 相似文献
908.
Takashi Ohta 《Journal of Turbulence》2017,18(6):497-511
Turbulent flow in the axial direction along a cylinder representing a monofilament yarn was reproduced for a relatively wide range of radius Reynolds numbers using direct numerical simulations. In the simulation of the thinnest cylinder, the friction coefficient agreed with a previously published formula. A pair of high- and low-speed streaks was detected around even the thinnest cylinder, whereby it was confirmed that turbulence was sustained according to the analysed turbulence statistics. Even when only a single pair of streaks around the cylinder was detected, the characteristics of the turbulence structures, such as the mean streak spacing based on the viscous length scale, were the same as those in flows over a flat plate. It was found that the friction coefficient changes in a way that maintains the structural characteristics of the flow, consistent with the view that universal characteristics of turbulence structures exist. 相似文献
909.
Don Koks 《Foundations of Physics》2017,47(4):505-531
The disk that rotates in an inertial frame in special relativity has long been analysed by assuming a Lorentz contraction of its peripheral elements in that frame, which has produced widely varying views in the literature. We show that this assumption is unnecessary for a disk that corresponds to the simplest form of rotation in special relativity. After constructing such a disk and showing that observers at rest on it do not constitute a true rotating frame, we choose a “master” observer and calculate a set of disk coordinates and spacetime metric pertinent to that observer. We use this formalism to resolve the “circular twin paradox”, then calculate the speed of light sent around the periphery as measured by the master observer, to show that this speed is a function of sent-direction and disk angle traversed. This result is consistent with the Sagnac Effect, but constitutes a finer analysis of that effect, which is normally expressed using an average speed for a full trip of the periphery. We also use the formalism to give a resolution of “Selleri’s paradox”. 相似文献
910.
Andrei Khrennikov 《Foundations of Physics》2017,47(8):1077-1099
We discuss the problems of quantum theory (QT) complicating its merging with general relativity (GR). QT is treated as a general theory of micro-phenomena—a bunch of models. Quantum mechanics (QM) and quantum field theory (QFT) are the most widely known (but, e.g., Bohmian mechanics is also a part of QT). The basic problems of QM and QFT are considered in interrelation. For QM, we stress its nonrelativistic character and the presence of spooky action at a distance. For QFT, we highlight the old problem of infinities. And this is the main point of the paper: it is meaningless to try to unify QFT so heavily suffering of infinities with GR. We also highlight difficulties of the QFT-treatment of entanglement. We compare the QFT and QM based measurement theories by presenting both theoretical and experimental viewpoints. Then we discuss two basic mathematical constraints of both QM and QFT, namely, the use of real (and, hence, complex) numbers and the Hilbert state space. We briefly present non-archimedean and non-hilbertian approaches to QT and their consequences. Finally, we claim that, in spite of the Bell theorem, it is still possible to treat quantum phenomena on the basis of a classical-like causal theory. We present a random field model generating the QM and QFT formalisms. This emergence viewpoint can serve as the basis for unification of novel QT (may be totally different from presently powerful QM and QFT) and GR. (It may happen that the latter would also be revolutionary modified.) 相似文献