全文获取类型
收费全文 | 434838篇 |
免费 | 5538篇 |
国内免费 | 1227篇 |
专业分类
化学 | 233309篇 |
晶体学 | 6415篇 |
力学 | 18763篇 |
综合类 | 13篇 |
数学 | 49945篇 |
物理学 | 133158篇 |
出版年
2021年 | 3747篇 |
2020年 | 4190篇 |
2019年 | 4526篇 |
2018年 | 5858篇 |
2017年 | 5744篇 |
2016年 | 8834篇 |
2015年 | 5566篇 |
2014年 | 8553篇 |
2013年 | 20204篇 |
2012年 | 15660篇 |
2011年 | 19285篇 |
2010年 | 13511篇 |
2009年 | 13362篇 |
2008年 | 17665篇 |
2007年 | 17556篇 |
2006年 | 16272篇 |
2005年 | 14568篇 |
2004年 | 13550篇 |
2003年 | 11910篇 |
2002年 | 11748篇 |
2001年 | 13439篇 |
2000年 | 10094篇 |
1999年 | 7927篇 |
1998年 | 6573篇 |
1997年 | 6318篇 |
1996年 | 6088篇 |
1995年 | 5471篇 |
1994年 | 5400篇 |
1993年 | 5201篇 |
1992年 | 5836篇 |
1991年 | 5927篇 |
1990年 | 5667篇 |
1989年 | 5479篇 |
1988年 | 5497篇 |
1987年 | 5379篇 |
1986年 | 5095篇 |
1985年 | 6563篇 |
1984年 | 6697篇 |
1983年 | 5305篇 |
1982年 | 5389篇 |
1981年 | 5372篇 |
1980年 | 4959篇 |
1979年 | 5357篇 |
1978年 | 5493篇 |
1977年 | 5391篇 |
1976年 | 5336篇 |
1975年 | 4914篇 |
1974年 | 4847篇 |
1973年 | 4850篇 |
1972年 | 3432篇 |
排序方式: 共有10000条查询结果,搜索用时 359 毫秒
11.
Aequationes mathematicae - In this paper, we establish a new class of dynamic inequalities of Hardy’s type which generalize and improve some recent results given in the literature. More... 相似文献
12.
Yuki Shintani Taku Ohtomi Dr. Aya Shibata Dr. Yoshiaki Kitamura Koichiro M. Hirosawa Prof. Kenichi G. N. Suzuki Prof. Masato Ikeda 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(8):e202104421
Aqueous self-assembly of short peptides has attracted growing attention for the construction of supramolecular materials for various bioapplications. Herein, we describe how the thermolysin-assisted biocatalytic construction of a dipeptide hydrazide from an N-protected amino acid and an amino acid hydrazide leads to the formation of thermally stable supramolecular hydrogels. In addition, we demonstrate the post-assembly modification of the supramolecular architectures constructed in situ tethering hydrazide groups as a chemical handle by means of fluorescence imaging. 相似文献
13.
Journal of Structural Chemistry - Atomic and electronic structures of cyclic organosilicon compound 9,9,10,10-tetraethynyl-9,10-dihydrodisilaanthracene are studied by the density functional theory.... 相似文献
14.
Filatova S. M. Guseva M. K. Bodrova T. G. Parshina D. V. Budanova U. A. Sebyakin Yu. L. 《Russian Journal of General Chemistry》2022,91(1):S13-S23
Russian Journal of General Chemistry - The review article traces the main trends of the synthetic approach to the solution of the problem of overcoming the resistance of pathogenic bacterial... 相似文献
15.
Journal of Analytical Chemistry - The present study reports the development of a magnetic polyethylene glycol nanocomposite based on graphite reinforcement carbon paste electrode for the sensitive... 相似文献
16.
Varfolomeev S. D. Panin A. A. Semenova N. A. Ublinskiy M. V. Akhadov T. A. Bykov V. I. Tsybenova S. B. 《Russian Chemical Bulletin》2022,71(3):591-594
A kinetic study of the effect of thermoheliox (inhalation of a helium and oxygen mixture, 70 °C) on the functional hemodynamics of the human brain by functional magnetic resonance imaging was carried out. The dynamic responses of the BOLD signal were found to be biphasic. An empirical equation describing the first phase of the hemodynamic response to visual stimulus was proposed. It was shown that preliminary inhalation of thermoheliox stimulates the hemodynamic responses by slowing down the vasoconstriction.
相似文献17.
Siberian Mathematical Journal - Let $ \{(A_{i},B_{i})\}_{i=1}^{m} $ be a set pair system. Füredi, Gyárfás, and Király called it $ 1 $ -cross intersecting if $... 相似文献
18.
Kento Nishikibe Keisuke Nishikawa Momochika Kumagai Matsumi Doe Yoshiki Morimoto 《化学:亚洲杂志》2022,17(1):e202101137
There are marine cytotoxic bromotriterpenoids, named the thyrsiferol family that are structurally characterized by some tetrahydropyran (THP) and tetrahydrofuran (THF) rings. The thyrsiferol family belongs to natural products that are often difficult to determine their stereostructures even by the current, highly advanced spectroscopic methods, especially in acyclic systems including stereogenic tetrasubstituted carbon centers. In such cases, it is effective to predict and synthesize the possible stereostructures. Herein, to elucidate ambiguous stereostructures and unassigned absolute configurations of aplysiol B, laurenmariannol, and saiyacenol A, members of the thyrsiferol family, we carried out their asymmetric chemical syntheses featuring 6-exo and 5-exo oxacyclizations of epoxy alcohol precursors and 6-endo bromoetherification of a bishomoallylic alcohol. In this paper, we report total assignments of their stereostructures through their asymmetric chemical syntheses and also their preliminary cytotoxic activities against some tumor cells. These results could not have been achieved without depending on asymmetric total synthesis. 相似文献
19.
Analysis Mathematica - In this paper, we discuss measure theoretic characterizations for Moore-Penrose inverse of Lambert conditional operators, denoted by (MwEMu)?, in some operator classes... 相似文献
20.
Numerical Algorithms - This paper considers different versions of block-column iterative (BCI) methods for solving nonnegative constrained linear least squares problems. We present the convergence... 相似文献