全文获取类型
收费全文 | 409389篇 |
免费 | 3368篇 |
国内免费 | 1387篇 |
专业分类
化学 | 214719篇 |
晶体学 | 6546篇 |
力学 | 17885篇 |
综合类 | 7篇 |
数学 | 46789篇 |
物理学 | 128198篇 |
出版年
2020年 | 3418篇 |
2019年 | 3914篇 |
2018年 | 5284篇 |
2017年 | 5147篇 |
2016年 | 7346篇 |
2015年 | 4384篇 |
2014年 | 7125篇 |
2013年 | 17821篇 |
2012年 | 13170篇 |
2011年 | 16234篇 |
2010年 | 11581篇 |
2009年 | 11469篇 |
2008年 | 15255篇 |
2007年 | 15346篇 |
2006年 | 14398篇 |
2005年 | 13064篇 |
2004年 | 11858篇 |
2003年 | 10650篇 |
2002年 | 10545篇 |
2001年 | 11646篇 |
2000年 | 9077篇 |
1999年 | 6988篇 |
1998年 | 5985篇 |
1997年 | 5940篇 |
1996年 | 5604篇 |
1995年 | 4882篇 |
1994年 | 4939篇 |
1993年 | 4982篇 |
1992年 | 5276篇 |
1991年 | 5469篇 |
1990年 | 5160篇 |
1989年 | 5138篇 |
1988年 | 5081篇 |
1987年 | 4950篇 |
1986年 | 4692篇 |
1985年 | 6331篇 |
1984年 | 6616篇 |
1983年 | 5332篇 |
1982年 | 5758篇 |
1981年 | 5592篇 |
1980年 | 5295篇 |
1979年 | 5576篇 |
1978年 | 5764篇 |
1977年 | 5730篇 |
1976年 | 5782篇 |
1975年 | 5333篇 |
1974年 | 5385篇 |
1973年 | 5485篇 |
1972年 | 3819篇 |
1971年 | 3277篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
71.
V. L. Gilyarov A. I. Slutsker V. P. Volodin L. A. Laius 《Physics of the Solid State》1997,39(1):132-135
The dependence of the energy characteristics on an adiabatically slowly increasing external force is determined analytically
for an anharmonic oscillator. The analytical results are confirmed by a numerical calculation. The nature of the force dependences
of the energy characteristics are determined and discussed.
Fiz. Tverd. Tela (St. Petersburg) 39, 153–157 (January 1997) 相似文献
72.
Flowing and static gas-phase samples of HNO3 in O2 and N2 were analyzed by long-path ultraviolet/visible (UV/VIS) spectroscopy to reveal the presence of both NO2 and NO3, the concentrations of which were calculated using differential absorption cross sections. NO2 is produced predominantly by the heterogeneous decomposition of HNO3, whereas NO3 is generated in the gas phase by the thermal decomposition of N2O5, a product of the self-disproportionation of liquid HNO3. © 1993 John Wiley & Sons, Inc. 相似文献
73.
The gauge compensation fields induced by the differential operators of the Stueckelberg-Schrödinger equation are discussed, as well as the relation between these fields and the standard Maxwell fields; An action is constructed and the second quantization of the fields carried out using a constraint procedure. The properties of the second quantized matter fields are discussed. 相似文献
74.
75.
Modeling and numerical simulations of the convective flows induced by the vibration of the monocrystal during crystal growth have been performed for two configurations simulating the Cz and FZ methods. This permitted to emphasize the role of different vibrational mechanisms in the formation of the average flows. It is shown that an appropriate combination of these mechanisms can be used to counteract the usual convective flows (buoyancy- and/or thermocapillary-driven) inherent to crystal growth processes from the liquid phase. While vibrational convection is rather complex due to these identified mechanisms, the new modeling used in the present paper opens up very promising perspectives to efficiently control heat and mass transfer during real industrial applications of crystal growth from the liquid phase. 相似文献
76.
A generalization of strong regularity around a vertex subset C of a graph Γ, which makes sense even if Γis non-regular, is studied. Such a structure appears, together with a kind of distance-regularity around C , when an spectral bound concerning the so-called predistance polynomial of C is attained. As a main consequence of these results, it is shown that a regular (connected) graph Γwith d + 1 distinct eigenvalues is distance-regular, and its distance- d graph Γ d is strongly regular with parameters a = c , if and only if the number of vertices at distance d from each vertex satisfies an expression which depends only on the order of Γand the different eigenvalues of Γ. 相似文献
77.
D. Citterio Stefan Rásonyi Ursula E. Spichiger 《Fresenius' Journal of Analytical Chemistry》1996,354(7-8):836-840
New chromoionophores have been developed, focused on NIR applications so that optode membranes may be used in monolithically integrated optical sensors. The wavelength of maximum absorbance has been estimated for a new model compound by the Pariser-Parr-Pople (PPP) method. Several cyanine type dyes have been tested as membrane chromoionophores. Membrane composition has been altered to overcome solubility problems. In this way, simple pH-sensitive optode membranes have been produced. 相似文献
78.
H.-J. Sue E. I. Garcia-Meitin N. A. Orchard 《Journal of Polymer Science.Polymer Physics》1993,31(5):595-608
The fracture behavior of a core-shell rubber (CSR) modified epoxy is investigated using both fracture mechanics and microscopy tools. The CSR-modified epoxy is found to be toughened via numerous line-array cavitations of the CSR particles, followed by plastic flow of the epoxy matrix. The toughening effect via the above craze-like damage process is found to be as effective as that of the well-known widespread rubber cavitation/matrix shear yielding mechanisms. The conditions for triggering the craze-like damage appear to be both stress state and rubber concentration dependent. The type of rubber tougheners utilized also plays a critical role in triggering this rather unusual craze-like damage in epoxy systems. © 1993 John Wiley & Sons, Inc. 相似文献
79.
80.
M. Trunk J. Popp I. Hartmann M. Lankers E. Urlaub W. Kiefer 《Fresenius' Journal of Analytical Chemistry》1996,355(3-4):354-356
In situ measurements of gas-liquid surface reactions of single aerosol microdroplets are presented. By means of optical levitation in combination with elastic (Mie) and inelastic (Raman) light scattering it is possible to get information on the chemistry of e.g. acid/base reactions as well as the physical behavior of single microparticles. 相似文献