全文获取类型
收费全文 | 1379篇 |
免费 | 27篇 |
国内免费 | 9篇 |
专业分类
化学 | 729篇 |
晶体学 | 3篇 |
力学 | 33篇 |
数学 | 364篇 |
物理学 | 286篇 |
出版年
2023年 | 7篇 |
2022年 | 18篇 |
2021年 | 14篇 |
2020年 | 19篇 |
2019年 | 26篇 |
2018年 | 28篇 |
2017年 | 26篇 |
2016年 | 39篇 |
2015年 | 37篇 |
2014年 | 37篇 |
2013年 | 98篇 |
2012年 | 106篇 |
2011年 | 76篇 |
2010年 | 44篇 |
2009年 | 47篇 |
2008年 | 84篇 |
2007年 | 73篇 |
2006年 | 70篇 |
2005年 | 68篇 |
2004年 | 72篇 |
2003年 | 51篇 |
2002年 | 29篇 |
2001年 | 31篇 |
2000年 | 31篇 |
1999年 | 28篇 |
1998年 | 9篇 |
1997年 | 11篇 |
1996年 | 9篇 |
1995年 | 16篇 |
1994年 | 13篇 |
1993年 | 13篇 |
1992年 | 14篇 |
1991年 | 8篇 |
1990年 | 8篇 |
1989年 | 5篇 |
1988年 | 6篇 |
1985年 | 11篇 |
1984年 | 10篇 |
1983年 | 6篇 |
1982年 | 13篇 |
1981年 | 12篇 |
1980年 | 5篇 |
1979年 | 8篇 |
1978年 | 9篇 |
1977年 | 10篇 |
1976年 | 10篇 |
1975年 | 9篇 |
1974年 | 13篇 |
1973年 | 6篇 |
1960年 | 3篇 |
排序方式: 共有1415条查询结果,搜索用时 265 毫秒
1.
Kavitha Telikepalli Király Tamás Matuschke Jannik Schlotter Ildikó Schmidt-Kraepelin Ulrike 《Mathematical Programming》2022,192(1-2):567-595
Mathematical Programming - Let G be a digraph where every node has preferences over its incoming edges. The preferences of a node extend naturally to preferences over branchings, i.e., directed... 相似文献
2.
Huan Yang Ying Zhou Pingtian Yu Yaya Yang Zhaoqun Jiao James P. Tam 《Natural product research》2019,33(9):1251-1256
A novel PCR technology was developed to detect short DNA fragments using species-specific primers for rapid and non-sequencing authentication of Bombyx batryticatus based on differences in the mitochondrial genome. Three specifically designed primer reactions were established to target species for the reliable identification of their commercial products. They were confirmed to have a high inter-species specificity and intra-species stability. The limit of detection was estimated as 1 ng of genomes for Beauveria bassiana and 100 pg for Bombyx mori and Metarhizium anisopliae. Furthermore, validation results demonstrated that raw materials and their processed products can be conveniently authenticated with good sensitivity and precision using this newly proposed approach. In particular, when counterfeits were assayed, these primer sets performed well, whereas COI barcoding technology did not. These could also assist in the discrimination and identification of adulterates of other animal-derived medicines in their pulverized and processed forms and even in complexes. 相似文献
3.
The minor relation of functions is generalized to multisorted functions. Pippenger’s Galois theory for minor-closed sets of functions is extended to multisorted functions and multisorted relation pairs. Reflections of minor-closed sets are again minor-closed, and the effect of reflections on the invariant relation pairs of minor-closed sets of multisorted functions is described. 相似文献
4.
Nguyen Van Hung Vo Minh Tam Dumitru Baleanu 《Mathematical Methods in the Applied Sciences》2020,43(7):4614-4626
In this paper, we consider a class of split mixed vector quasivariational inequality problems in real Hilbert spaces and establish new gap functions by using the method of the nonlinear scalarization function. Further, we obtain some error bounds for the underlying split mixed vector quasivariational inequality problems in terms of regularized gap functions. Finally, we give some examples to illustrate our results. The results obtained in this paper are new. 相似文献
5.
6.
7.
8.
9.
Expedient and Diastereodivergent Assembly of Terpenoid Decalin Subunits having Quaternary Stereocenters through Organocatalytic Robinson Annulation of Nazarov Reagent 下载免费PDF全文
Barbara Berkes Kristóf Ozsváth Laura Molnár Tamás Gáti Tamás Holczbauer György Kardos Tibor Soós 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(50):18101-18106
We report an expedient approach to highly functionalized cis‐ and trans‐decalines that could function as key structural subunits toward the synthesis of various classes of terpenoids. Key to the strategy is an organocatalyzed Robinson annulation reaction of the Nazarov reagent that affords chiral enone building blocks with high enantioselectivities. The quaternary carbon stereogenic center can direct the subsequent reactions and allow the rapid and diastereoconvergent assembly of complex decalines with contiguous stereocenters. 相似文献
10.
Nonlinear Dynamics - This work is based on the observation that the first Poincaré–Lyapunov constant is a quadratic function of the coefficients of the two-dimensional vector field at a... 相似文献