全文获取类型
收费全文 | 364586篇 |
免费 | 5549篇 |
国内免费 | 2640篇 |
专业分类
化学 | 177737篇 |
晶体学 | 5471篇 |
力学 | 18101篇 |
综合类 | 77篇 |
数学 | 53257篇 |
物理学 | 118132篇 |
出版年
2021年 | 2238篇 |
2020年 | 2464篇 |
2019年 | 2760篇 |
2018年 | 11598篇 |
2017年 | 12328篇 |
2016年 | 8712篇 |
2015年 | 4367篇 |
2014年 | 5258篇 |
2013年 | 13057篇 |
2012年 | 14227篇 |
2011年 | 24231篇 |
2010年 | 15149篇 |
2009年 | 14981篇 |
2008年 | 20892篇 |
2007年 | 24230篇 |
2006年 | 10109篇 |
2005年 | 15871篇 |
2004年 | 11418篇 |
2003年 | 10350篇 |
2002年 | 8262篇 |
2001年 | 8336篇 |
2000年 | 6443篇 |
1999年 | 4899篇 |
1998年 | 4084篇 |
1997年 | 4065篇 |
1996年 | 3849篇 |
1995年 | 3524篇 |
1994年 | 3390篇 |
1993年 | 3321篇 |
1992年 | 3611篇 |
1991年 | 3623篇 |
1990年 | 3411篇 |
1989年 | 3349篇 |
1988年 | 3365篇 |
1987年 | 3205篇 |
1986年 | 3090篇 |
1985年 | 4156篇 |
1984年 | 4316篇 |
1983年 | 3520篇 |
1982年 | 3863篇 |
1981年 | 3749篇 |
1980年 | 3622篇 |
1979年 | 3665篇 |
1978年 | 3901篇 |
1977年 | 3646篇 |
1976年 | 3895篇 |
1975年 | 3466篇 |
1974年 | 3576篇 |
1973年 | 3916篇 |
1972年 | 2374篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
131.
N. I. Golovina G. N. Nechiporenko G. G. Nemtsev G. P. Dolganova V. P. Roshchupkin D. B. Lempert G. B. Manelis 《Russian Journal of Applied Chemistry》2007,80(1):24-30
Methods for phase stabilization of ammonium nitrate were sought for in order to considerably expand the application area of this oxidizing agent in various-purpose self-combustible formulations, including that in a new generation of gas-generating formulations for automobile air bags. New methods for stabilization of ammonium nitrate were studied and, in particular, a search was made for organic compounds that can stabilize ammonium nitrate even at their low content. The mechanism of phase state stabilization of ammonium nitrate by compounds of this kind was examined. 相似文献
132.
Yu. V. Pokonova 《Russian Journal of Applied Chemistry》2007,80(12):2163-2164
Kinetic, sorption and selectivity properties of commercial adsorbents are improved by adding petroleum residues (tar asphaltene concentrates) 13% of whole mass. Obtained adsorbents can be used for selective extraction of nobel metals from multicomponent polymetallic solutions of heavy metals and fro sewages purification for removing arsenic. 相似文献
133.
G. Panina 《Central European Journal of Mathematics》2003,1(2):157-168
All 3-dimensional convex polytopes are known to be rigid. Still their Minkowski differences (virtual polytopes) can be flexible
with any finite freedom degree. We derive some sufficient rigidity conditions for virtual polytopes and present some examples
of flexible ones. For example, Bricard's first and second flexible octahedra can be supplied by the structure of a virtual
polytope. 相似文献
134.
135.
R. Notoya 《Russian Journal of Electrochemistry》2002,38(3):255-260
It is found that the density (number of the component ion or molecule in 1 cm3) of a molten salt could be expressed as a function of the product of the electron donating and accepting properties of the component anion and cation. This equation is very useful for estimating the density of any molten salt at high temperature with the standard deviation accurately. 相似文献
136.
137.
Investigated is the dependency of the crack tip opening displacement (CTOD) on the local microstructure of the heat affected zone in high-strength low-alloy (HSLA) microalloyed steel. Since the initiation of the crack tip location could not be controlled in fatigue, any possible correlation between heat iput in welding and fracture toughness could be smeared. Modified CTOD data are defined; they show that the fracture resistance of the weld joint decreased as the heat input increased. 相似文献
138.
An analysis is made of the conditions of formation and the stability region of static-soliton-type magnetic nonuniformities
in a (001)-crystal plate with combined anisotropy. It is shown that if demagnetizing fields in the plate are taken into account,
static solitons can localize at certain defects for appropriate parameters of the material. The soliton stability region was
found to be bounded by two extreme values of the material parameters, namely, those at which the soliton is unstable against
collapse and at which it expands. It was also found that the soliton stability region differs considerably from that predicted
theoretically in the model disregarding the finite size of the sample and the presence of defects.
Fiz. Tverd. Tela (St. Petersburg) 40, 1498–1502 (August 1998) 相似文献
139.
The barotropic compressible Navier–Stokes equations in an unbounded domain are studied. We prove the unique existence of the solution (u, p) of the system (1.1) in the Sobolev spaceHk + 3 × Hk + 2provided that the derivatives of the data of the problem are sufficiently small, wherek ≥ 0 is any integer. The proof follows from an analysis of the linearized problem, the solvability of the continuity equation, and the Schauder fixed point theory. Similar smoothness results are obtained for a linearized form of (1.1). 相似文献
140.
R. Plaga 《Foundations of Physics》1997,27(4):559-577
The many-worlds interpretation of quantum mechanics predicts the formation of distinct parallel worlds as a result, of a quantum
mechanical measurement. Communication among these parallel worlds would experimentally rule out alternatives to this interpretation.
A possible procedure for “interworld” exchange of information and energy, using only state of the art quantum optical equipement,
is described. A single ion is isolated from its environment in an ion trap. Then a quantum mechanical measurement with two
discrete outcomes is performed on another system, resulting in the formation of two parallel worlds. Depending on the outcome
of this measurement the ion is excited from only one of the parallel worlds before the ion decoheres through its interaction
with the environment. A detection of this excitation in the other parallel world is direct evidence for the many-worlds interpretation.
This method could have important practical applications in physics and beyond. 相似文献