全文获取类型
收费全文 | 61664篇 |
免费 | 1870篇 |
国内免费 | 166篇 |
专业分类
化学 | 38018篇 |
晶体学 | 386篇 |
力学 | 1008篇 |
综合类 | 5篇 |
数学 | 11348篇 |
物理学 | 12935篇 |
出版年
2023年 | 394篇 |
2022年 | 605篇 |
2021年 | 830篇 |
2020年 | 890篇 |
2019年 | 913篇 |
2018年 | 1144篇 |
2017年 | 1077篇 |
2016年 | 2057篇 |
2015年 | 1728篇 |
2014年 | 1751篇 |
2013年 | 3797篇 |
2012年 | 3688篇 |
2011年 | 3687篇 |
2010年 | 2479篇 |
2009年 | 2198篇 |
2008年 | 3249篇 |
2007年 | 3064篇 |
2006年 | 2752篇 |
2005年 | 2694篇 |
2004年 | 2267篇 |
2003年 | 1929篇 |
2002年 | 1669篇 |
2001年 | 1304篇 |
2000年 | 1243篇 |
1999年 | 901篇 |
1998年 | 701篇 |
1997年 | 651篇 |
1996年 | 815篇 |
1995年 | 582篇 |
1994年 | 663篇 |
1993年 | 620篇 |
1992年 | 634篇 |
1991年 | 530篇 |
1990年 | 568篇 |
1989年 | 468篇 |
1988年 | 458篇 |
1987年 | 442篇 |
1986年 | 417篇 |
1985年 | 555篇 |
1984年 | 530篇 |
1983年 | 413篇 |
1982年 | 415篇 |
1981年 | 425篇 |
1980年 | 370篇 |
1979年 | 341篇 |
1978年 | 321篇 |
1977年 | 325篇 |
1976年 | 332篇 |
1974年 | 289篇 |
1973年 | 312篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
102.
Periodica Mathematica Hungarica - In our paper we study the usage of partially defined Boolean functions (PDBFs) for generating cryptographically strong Boolean functions. A PDBF can be considered... 相似文献
103.
A note on a generalized Douglas space 总被引:1,自引:0,他引:1
Periodica Mathematica Hungarica - 相似文献
104.
Paramagnetic pyrroline and 1,2,3,6-tetrahydropyridine derivatives of BODIPY and their diamagnetic analogs have been synthesized and characterized as novel redox double sensor and cation sensitive reagents. 相似文献
105.
The influence of the sample orientation on the effective value of the hydrostatic piezoelectric coefficients d
h
(i)
of Sn2P2S6 crystals has been studied. The hydrostatic piezoelectric coefficients d
h
(1)
and d′
h
(3)
, were measured, d
h
(1)
=(244±3) pC/N and d′
h
(3)
=(92±1) pC/N. The hydrostatic piezoelectric coefficient d
h
(3)
for orthogonal axis system was calculated to be d
h
(3)
=(87±2) pC/N. The, optimal orientation of the sample has been found as (Xy l)−20°-cut. Maximal value of the effective hydrostatic piezoelectric coefficient d
h
(1)
equals 260 pC/N. Double rotated samples were also studied. The orientation of the samples insensitive to the pressure has
been found. The theoretical mean value of hydrostatic piezoelectric coefficient (d
h
)
mean
corresponding to randomly oriented Sn2P2S6 grains in a poled composite has been calculated to be (d
h
)
mean
=136 pC/N. 相似文献
106.
The function lattice, or generalized Boolean algebra, is the set of ℓ-tuples with the ith coordinate an integer between 0 and a bound ni. Two ℓ-tuples t-intersect if they have at least t common nonzero coordinates. We prove a Hilton–Milner type theorem for systems of t-intersecting ℓ-tuples.Received September 29, 2004 相似文献
107.
Sufficient conditions which guarantee that certain linear integro-differential equation cannot have a positive solution are
established. 相似文献
108.
Máté Matolcsi 《Acta Mathematica Hungarica》2005,108(1-2):129-136
Summary He present work deals with estimations of the n-th linear polarization constant c(H)n of an n-dimensional real Hilbert space H. We provide some new lower bounds on the value of sup║y║=1 │1,y> ... n,y>│, where x1, ... ,xn are unit vectors in H. In particular, the results improve an earlier estimate of Marcus. However, the intriguing conjecture c(H) n= nn/2 remains open. 相似文献
109.
110.
No analytic solutions of the Schrödinger equation are known for the quartic anharmonic oscillator. We show in this paper that there are closely related modified quartic oscillators with the potential depending on |x| for which analytic solutions for some states exist. These results can be extended to the higher order oscillators 相似文献