全文获取类型
收费全文 | 147590篇 |
免费 | 13139篇 |
国内免费 | 7631篇 |
专业分类
化学 | 73130篇 |
晶体学 | 1388篇 |
力学 | 11047篇 |
综合类 | 314篇 |
数学 | 39434篇 |
物理学 | 43047篇 |
出版年
2024年 | 280篇 |
2023年 | 1607篇 |
2022年 | 2723篇 |
2021年 | 2792篇 |
2020年 | 3119篇 |
2019年 | 2909篇 |
2018年 | 12309篇 |
2017年 | 11954篇 |
2016年 | 9241篇 |
2015年 | 4281篇 |
2014年 | 4417篇 |
2013年 | 5602篇 |
2012年 | 10307篇 |
2011年 | 16749篇 |
2010年 | 9862篇 |
2009年 | 9986篇 |
2008年 | 10893篇 |
2007年 | 12561篇 |
2006年 | 3962篇 |
2005年 | 4388篇 |
2004年 | 3892篇 |
2003年 | 3820篇 |
2002年 | 2720篇 |
2001年 | 1709篇 |
2000年 | 1643篇 |
1999年 | 1681篇 |
1998年 | 1493篇 |
1997年 | 1433篇 |
1996年 | 1484篇 |
1995年 | 1167篇 |
1994年 | 995篇 |
1993年 | 855篇 |
1992年 | 726篇 |
1991年 | 641篇 |
1990年 | 550篇 |
1989年 | 442篇 |
1988年 | 394篇 |
1987年 | 331篇 |
1986年 | 306篇 |
1985年 | 250篇 |
1984年 | 185篇 |
1983年 | 138篇 |
1982年 | 121篇 |
1981年 | 105篇 |
1980年 | 111篇 |
1979年 | 77篇 |
1978年 | 64篇 |
1977年 | 58篇 |
1976年 | 46篇 |
1973年 | 53篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
191.
X Y Liu C J Li 《Science in China. Series B, Chemistry, life sciences & earth sciences》1989,32(10):1215-1223
To further evaluate the causality between endogenous pyrogen (EP)-induced fever and cyclic adenosine-3',5'-monophosphate (cyclic AMP) level, the effects of sodium salicylate (SS) on the febrile response and increased levels of cyclic AMP in both cerebrospinal fluid (c.s.f.) and plasma during EP-induced fever in rabbits were observed. The results suggest that cyclic AMP is probably involved in the central mediation of EP-induced fever and that increased concentration of cyclic AMP in c.s.f. associated with EP-induced fever is not the result of temperature elevation but appears to be caused by the increased synthesis in the central nervous system. In addition it is confirmed that blood is impossibly a contributory source of increased cyclic AMP in c.s.f. during EP fever, and that SS may act subsequent to the increase in cyclic AMP. 相似文献
192.
Comprehensive studies of X-ray diffraction, oxygen content, superconductivity and Mössbauer effect have been made on FexCu1−xBa2YCu2O7+y superconductors (0.00≤x≤0.70) synthesized by ambient (AM) and high pressure (HP). Results indicate that all the HP-samples have tetragonal structure, smaller lattice parameter c and unit-cell volume than the AM-samples. The studies of oxygen content, and Mössbauer spectroscopy indicate that the HP-samples have higher oxygen content, carrier concentration and average valence of Fe than the AM-samples. Moreover, for the HP-samples more Fe atoms located in CuOx chains have fivefold-oxygen coordination. These are important reasons for the enhancement of Tc in the HP-samples. 相似文献
193.
194.
In this paper we obtain a number of Maharam-type slice integral representations, with respect to scalar measures, for positive
projections in Dedekind complete vector lattices and f-algebras.
AMS Classification: 47B65, 46A40, 06F25 相似文献
195.
In this paper, the transformation processes of two types of bis(8-hydroxyquinoline)zinc: Znq2 dihydrate and anhydrous (Znq2)4 were investigated by X-ray diffraction (XRD), infrared spectra (IR), scanning electron microscope (SEM), differential scanning calorimetry (DSC) and thermogravimetry (TG). The effects of crystal structure on optical properties of bis(8-hydroxyquinoiline)zinc were analyzed. Znq2 dihydrate can be transformed into anhydrous (Znq2)4 during heating under vacuum. Reversal transformation occurs by the interaction between chloroform and (Znq2)4. But (Znq2)4 was partially transformed into Znq2 dihydrate by the interaction between ethanol and (Znq2)4. The different molecular structure results in different crystal stacking and electronic structure, thereby affect its optical properties. 相似文献
196.
Valery V. Kiselev 《Central European Journal of Physics》2004,2(3):523-534
We calculate the leptonic constant for the pseudoscalar ground state of the B
c
meson in the framework of a QCD-motivated potential model taking into account the two-loop anomalous dimension for the heavy
quark current in nonrelativistic QCD as matched with full QCD. 相似文献
197.
Gaston Casanova 《Advances in Applied Clifford Algebras》2004,14(2):249-252
We define analytic functions within Clifford Algebras CL, and study their trigonometric properties. We write the addition formulas when their arguments, A and B in CL, commute, this generalizes ordinary trigonometry. We examine in particular the case A2 = 1.
相似文献
198.
M. Lashkarizadeh Bami 《Semigroup Forum》2004,69(2):219-229
In the present paper it is shown that if S1 and S2 are two
Clifford topological semigroups satisfying certain conditions
and T is an isometric isomorphism of LUC(S1*) onto LUC(S2*), then T
maps S1 topologically isomorphically onto S2. Furthermore, T
maps M
l
n(S1) (M(S1), respectively) isometrically
isomorphically onto M
l
n(S2) (M(S2), respectively). Indeed,
we have obtained a generalization of a well-known result of
Ghahramani, Lau and Losert for locally compact groups to a more
general setting of Clifford topological semigroups. 相似文献
199.
Continuity is obtained of some multilinear operators related to certain integral operators for the weighted Herz spaces with extreme exponents. The operators include the Littlewood–Paley and Marcinkiewicz operators. 相似文献
200.
Existence, Multiplicity and Infinite Solvability of Positive Solutions for One-Dimensional p-Laplacian 总被引:5,自引:0,他引:5
Qing Liu YAO 《数学学报(英文版)》2005,21(4):691-698
The existence, multiplicity and infinite solvability of positive solutions are established for some two-point boundary value problems of one-dimensional p-Laplacian. In this paper, by multiplicity we mean the existence of m solutions, where m is an arbitrary natural number. 相似文献