全文获取类型
收费全文 | 661898篇 |
免费 | 22129篇 |
国内免费 | 1851篇 |
专业分类
化学 | 372515篇 |
晶体学 | 9568篇 |
力学 | 30749篇 |
综合类 | 30篇 |
数学 | 78189篇 |
物理学 | 194827篇 |
出版年
2021年 | 6935篇 |
2020年 | 9476篇 |
2019年 | 7913篇 |
2018年 | 10230篇 |
2017年 | 8759篇 |
2016年 | 16674篇 |
2015年 | 11724篇 |
2014年 | 15666篇 |
2013年 | 32444篇 |
2012年 | 23855篇 |
2011年 | 26796篇 |
2010年 | 21504篇 |
2009年 | 21174篇 |
2008年 | 24487篇 |
2007年 | 24301篇 |
2006年 | 22069篇 |
2005年 | 19647篇 |
2004年 | 17974篇 |
2003年 | 16106篇 |
2002年 | 16057篇 |
2001年 | 18091篇 |
2000年 | 13814篇 |
1999年 | 10764篇 |
1998年 | 9193篇 |
1997年 | 9111篇 |
1996年 | 8555篇 |
1995年 | 7780篇 |
1994年 | 7795篇 |
1993年 | 7483篇 |
1992年 | 8266篇 |
1991年 | 8457篇 |
1990年 | 8061篇 |
1989年 | 7914篇 |
1988年 | 7757篇 |
1987年 | 7776篇 |
1986年 | 7353篇 |
1985年 | 9509篇 |
1984年 | 9877篇 |
1983年 | 8302篇 |
1982年 | 8593篇 |
1981年 | 8252篇 |
1980年 | 8145篇 |
1979年 | 8478篇 |
1978年 | 8903篇 |
1977年 | 8757篇 |
1976年 | 8837篇 |
1975年 | 8228篇 |
1974年 | 8344篇 |
1973年 | 8435篇 |
1972年 | 5996篇 |
排序方式: 共有10000条查询结果,搜索用时 109 毫秒
21.
Dr. Yolimar Gil Dr. Alejandro Castro-Alvarez Dr. Pablo Fuentealba Prof. Evgenia Spodine Dr. Daniel Aravena 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(48):e202200336
Enhancement of axial magnetic anisotropy is the central objective to push forward the performance of Single-Molecule Magnet (SMM) complexes. In the case of mononuclear lanthanide complexes, the chemical environment around the paramagnetic ion must be tuned to place strongly interacting ligands along either the axial positions or the equatorial plane, depending on the oblate or prolate preference of the selected lanthanide. One classical strategy to achieve a precise chemical environment for a metal centre is using highly structured, chelating ligands. A natural approach for axial-equatorial control is the employment of macrocycles acting in a belt conformation, providing the equatorial coordination environment, and leaving room for axial ligands. In this review, we present a survey of SMMs based on the macrocycle belt motif. Literature systems are divided in three families (crown ether, Schiff-base and metallacrown) and their general properties in terms of structural stability and SMM performance are briefly discussed. 相似文献
22.
Russian Chemical Bulletin - New representatives of (O-Si)-chelate compounds, N-(fluorosilyl)methyl derivatives of N-methylacetamide, N-methylbenzamide, N-phenylacetamide, and N-phenylbenzamide,... 相似文献
23.
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
24.
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
25.
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
26.
Tsyganova S. I. Fetisova O. Yu. Mazurova E. N. Taran O. P. Kuznetsov B. N. 《Russian Journal of Applied Chemistry》2022,95(3):408-416
Russian Journal of Applied Chemistry - A method for the disposal of hydrolysis lignin waste based on its modification with ZnCl2 and FeCl3 and subsequent carbonization at 800°C was proposed.... 相似文献
27.
Roopa K. P. Keshavamurthy K. Mahesh B. Veena K. P. Shankara B. S. Basavaiah K. 《Journal of Applied Spectroscopy》2022,89(4):809-818
Journal of Applied Spectroscopy - Three simple, sensitive, precise, and rapid spectrophotometric methods are developed and optimized for the assay of vardenafil in pharmaceutical formulations. The... 相似文献
28.
Gürbüzbalaban Mert Ruszczyński Andrzej Zhu Landi 《Journal of Optimization Theory and Applications》2022,194(3):1014-1041
Journal of Optimization Theory and Applications - We consider a distributionally robust formulation of stochastic optimization problems arising in statistical learning, where robustness is with... 相似文献
29.
Russian Journal of Applied Chemistry - In September 1975, the head of Russian electrochemists, Academician A.N. Frumkin (1895–1976), in his report at the XI Mendeleev Congress on General and... 相似文献
30.
Moroz Ya. A. Lozinskyy N. S. Lopanov A. N. Chebyshev K. A. 《Russian Journal of General Chemistry》2022,92(1):101-107
Russian Journal of General Chemistry - Tungstophosphatozincates with the Keggin anion structure Kt5[PW11O39Zn(H2O)]?nH2O, Kt = Rb+, Cs+, (CH3)4N+; (C2H5)4N+ were synthesized. Their... 相似文献