全文获取类型
收费全文 | 193486篇 |
免费 | 2942篇 |
国内免费 | 394篇 |
专业分类
化学 | 106669篇 |
晶体学 | 2233篇 |
力学 | 7326篇 |
综合类 | 8篇 |
数学 | 23586篇 |
物理学 | 57000篇 |
出版年
2021年 | 1406篇 |
2020年 | 1718篇 |
2019年 | 1739篇 |
2018年 | 2352篇 |
2017年 | 2253篇 |
2016年 | 3969篇 |
2015年 | 2820篇 |
2014年 | 3636篇 |
2013年 | 9029篇 |
2012年 | 7492篇 |
2011年 | 8589篇 |
2010年 | 5886篇 |
2009年 | 5638篇 |
2008年 | 7787篇 |
2007年 | 7656篇 |
2006年 | 7063篇 |
2005年 | 6713篇 |
2004年 | 5899篇 |
2003年 | 5113篇 |
2002年 | 4965篇 |
2001年 | 5131篇 |
2000年 | 4137篇 |
1999年 | 3136篇 |
1998年 | 2695篇 |
1997年 | 2573篇 |
1996年 | 2496篇 |
1995年 | 2269篇 |
1994年 | 2309篇 |
1993年 | 2123篇 |
1992年 | 2411篇 |
1991年 | 2454篇 |
1990年 | 2304篇 |
1989年 | 2237篇 |
1988年 | 2170篇 |
1987年 | 2048篇 |
1986年 | 1983篇 |
1985年 | 2581篇 |
1984年 | 2672篇 |
1983年 | 2175篇 |
1982年 | 2354篇 |
1981年 | 2270篇 |
1980年 | 2126篇 |
1979年 | 2263篇 |
1978年 | 2426篇 |
1977年 | 2306篇 |
1976年 | 2348篇 |
1975年 | 2229篇 |
1974年 | 2294篇 |
1973年 | 2295篇 |
1972年 | 1486篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
1.
2.
Inas A. Abdallah Sherin F. Hammad Alaa Bedair Mohamed A. Abdelaziz Neil D. Danielson Ahmed H. Elshafeey Fotouh R. Mansour 《Biomedical chromatography : BMC》2022,36(6):e5365
Favipiravir is a potential antiviral medication that has been recently licensed for Covid-19 treatment. In this work, a gadolinium-based magnetic ionic liquid was prepared and used as an extractant in dispersive liquid–liquid microextraction (DLLME) of favipiravir in human plasma. The high enriching ability of DLLME allowed the determination of favipiravir in real samples using HPLC/UV with sufficient sensitivity. The effects of several variables on extraction efficiency were investigated, including type of extractant, amount of extractant, type of disperser and disperser volume. The maximum enrichment was attained using 50 mg of the Gd-magnetic ionic liquid (MIL) and 150 μl of tetrahydrofuran. The Gd-based MIL could form a supramolecular assembly in the presence of tetrahydrofuran, which enhanced the extraction efficiency of favipiravir. The developed method was validated according to US Food and Drug Administration bioanalytical method validation guidelines. The coefficient of determination was 0.9999, for a linear concentration range of 25 to 1.0 × 105 ng/ml. The percentage recovery (accuracy) varied from 99.83 to 104.2%, with RSD values (precision) ranging from 4.07 to 11.84%. The total extraction time was about 12 min and the HPLC analysis time was 5 min. The method was simple, selective and sensitive for the determination of favipiravir in real human plasma. 相似文献
3.
Sakhautdinova G. F. Sakhautdinov I. M. Mustafin A. G. Yunusov M. S. 《Chemistry of Natural Compounds》2022,58(1):185-186
Chemistry of Natural Compounds - 相似文献
4.
Dominik Vítek Prof. Aleš Růžička Lise Vermeersch Dr. Libor Dostál Dr. Jan Turek Prof. Roman Jambor 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(70):e202202639
Reactivity studies of the GeII→B complex L(Cl)Ge⋅BH3 ( 1 ; L=2-Et2NCH2-4,6-tBu2-C6H2) were performed to determine the effect on the GeII→B donation. N-coordinated compounds L(OtBu)Ge⋅BH3 ( 2 ) and [LGe⋅BH3]2 ( 3 ) were prepared. The possible tuning of the GeII→B interaction was proved experimentally, yielding compounds 1-PPh2-8-(LGe)-C10H6 ( 4 ) and L(Cl)Ge⋅GaCl3 ( 5 ) without a GeII→B interaction. In 5 , an unprecedented GeII→Ga coordination was revealed. The experimental results were complemented by a theoretical study focusing on the bonding in 1 − 5 . The different strength of the GeII→E (E=B, Ga) donation was evaluated by using energy decomposition analysis. The basicity of different L(X)Ge groups through proton affinity is also assessed. 相似文献
5.
Peralta Cecilia Mariana Acosta Gimena Henestrosa Cecilia Gil Raúl Andrés Fernández Liliana Patricia 《Journal of Analytical Chemistry》2022,77(3):308-317
Journal of Analytical Chemistry - The present development involved a flow injection strategy using a mini-column of multiwalled carbon nanotubes and fluorescent detection (λex of 283 nm,... 相似文献
6.
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
7.
Bazarra Noelia Castejón Alberto Fernández José R. Quintanilla Ramón 《Meccanica》2021,56(12):3025-3037
Meccanica - In this work we study, from the numerical point of view, a one-dimensional thermoelastic problem where the thermal law is of type III. Quasi-static microvoids are also assumed within... 相似文献
8.
Set-Valued and Variational Analysis - In a Hilbert framework ℌ, we study the convergence properties of a Newton-like inertial dynamical system governed by a general maximally monotone... 相似文献
9.
Numerical Algorithms - In this paper, the block generalized product-type bi-conjugate gradient (GPBi-CG) method for solving large, sparse nonsymmetric linear systems of equations with multiple... 相似文献
10.