全文获取类型
收费全文 | 14309篇 |
免费 | 95篇 |
国内免费 | 84篇 |
专业分类
化学 | 6479篇 |
晶体学 | 84篇 |
力学 | 201篇 |
数学 | 5041篇 |
物理学 | 2683篇 |
出版年
2021年 | 109篇 |
2020年 | 104篇 |
2019年 | 107篇 |
2018年 | 176篇 |
2017年 | 209篇 |
2016年 | 169篇 |
2015年 | 212篇 |
2014年 | 281篇 |
2013年 | 739篇 |
2012年 | 417篇 |
2011年 | 473篇 |
2010年 | 378篇 |
2009年 | 404篇 |
2008年 | 531篇 |
2007年 | 544篇 |
2006年 | 525篇 |
2005年 | 433篇 |
2004年 | 336篇 |
2003年 | 372篇 |
2002年 | 320篇 |
2001年 | 332篇 |
2000年 | 334篇 |
1999年 | 280篇 |
1998年 | 224篇 |
1997年 | 202篇 |
1996年 | 227篇 |
1995年 | 200篇 |
1994年 | 219篇 |
1993年 | 166篇 |
1992年 | 194篇 |
1991年 | 218篇 |
1990年 | 275篇 |
1989年 | 237篇 |
1988年 | 279篇 |
1987年 | 236篇 |
1986年 | 197篇 |
1985年 | 226篇 |
1984年 | 237篇 |
1983年 | 141篇 |
1982年 | 218篇 |
1981年 | 207篇 |
1980年 | 182篇 |
1979年 | 163篇 |
1978年 | 192篇 |
1977年 | 162篇 |
1976年 | 165篇 |
1975年 | 131篇 |
1974年 | 151篇 |
1973年 | 164篇 |
1972年 | 91篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
81.
82.
Given an integer n ≥ 2, let λ(n) := (log n)/(log γ(n)), where γ(n) = Π
p|n p, stand for the index of composition of n, with λ(1) = 1. We study the distribution function of (λ(n) – 1) log n as n runs through particular sets of integers, such as the shifted primes, the values of a given irreducible cubic polynomial
and the shifted powerful numbers.
Research supported in part by a grant from NSERC.
Research supported by the Applied Number Theory Research Group of the Hungarian Academy of Science and by a grant from OTKA.
Professor M.V. Subbarao passed away on February 15, 2006.
Received: 3 March 2006 Revised: 28 October 2006 相似文献
83.
Please forward books for review to the book review editor: Magdolna Hargittai, Structural Chemistry Research Group of the Hungarian Academy of Sciences, Eötvös University, H-1431 Budapest, Pf. 117, Hungary 相似文献
84.
Z. Adonyi 《Journal of Thermal Analysis and Calorimetry》1994,42(2-3):491-503
Dimensionless number has been developed and introduced for quantitative analysis of the effect of thermogravimetric measuring factors like sample quantity, heating rate, etc. The TG, DTG and T data of different thermogravimetric measurements can be used directly for calculation of the three constants of analogy. TG data of CaCO3 measured in very different conditions show the method of transformation and its applicability for calculation of the correlation of measurements. 相似文献
85.
Tibor Cserháti 《Analytical and bioanalytical chemistry》1994,349(10-11):751-755
The interaction between 23 anticancer drugs and acetyl-β-cyclodextrin (acetyl-β-CD) was studied by reversed-phase charge-transfer thin-layer chromatography and the relative strength of interaction was calculated. Acetyl-β-CD formed inclusion complexes with 16 compounds, the complex always being more hydrophilic than the uncomplexed drug. The inclusion forming capacity of drugs differed considerably according to their chemical structure. The significant linear correlation between the hydrophobicity and specific hydrophobic surface area of anticancer drugs indicated that they can be considered as a homologous series of compounds, however, their chemical structures are highly different. 相似文献
86.
Domokos Szász 《Communications in Mathematical Physics》1992,145(3):595-604
TheK-property is demonstrated for a class of planar billiards satisfying Wojtkowski's principles. Their boundary may consist of convex-scattering, concave and linear pieces. Earlier Wojtkowski showed that these billards had non-zero Lyapunov exponents. 相似文献
87.
What is the maximum number of unit distances between the vertices of a convex n-gon in the plane? We review known partial results for this and other open questions on multiple occurrences of the same interpoint distance in finite planar subsets. Some new results are proved for small n. Challenging conjectures, both old and new, are highlighted. 相似文献
88.
89.
90.
Methotrexate (MTX) has been convalently attached to an IgG-type monoclonal antibody (791T/36) directed to tumour-associated antigen gp72. Conjugates were synthesized by the active ester method using MTX N-succinimidyl ester at various pH values (7.5-10.5). Following purification by gel filtration, high performance liquid chromatography was used to assess the free drug or its derivatives in samples of MTX-791T/36 conjugates previously treated (or not) with hydroxylamine. Quantitative analysis, performed on a reversed phase column (pore size 300 A) with isocratic acetonitrile-sodium acetate buffer (pH 4.8) as mobile phase, indicated no detectable amount of free methotrexate in hydroxylamine-treated conjugates even six months after their preparation. Similar observations were made with conjugates, whose synthesis were performed at pH greater than or equal to 10. In contrast, the presence of increasing amounts of drug/metabolite could be demonstrated in samples produced at lower pH values. Based on these findings, the pH-dependent kinetics of MTX release has been determined and used to design conditions under which stable MTX-791T/36 conjugates could be prepared without hydroxylamine reaction. 相似文献