全文获取类型
收费全文 | 60930篇 |
免费 | 4234篇 |
国内免费 | 2681篇 |
专业分类
化学 | 36743篇 |
晶体学 | 440篇 |
力学 | 1931篇 |
综合类 | 262篇 |
数学 | 9721篇 |
物理学 | 18748篇 |
出版年
2023年 | 547篇 |
2022年 | 666篇 |
2021年 | 888篇 |
2020年 | 1197篇 |
2019年 | 1134篇 |
2018年 | 1200篇 |
2017年 | 1159篇 |
2016年 | 2062篇 |
2015年 | 1823篇 |
2014年 | 2050篇 |
2013年 | 3626篇 |
2012年 | 3531篇 |
2011年 | 3819篇 |
2010年 | 2601篇 |
2009年 | 2359篇 |
2008年 | 3280篇 |
2007年 | 3030篇 |
2006年 | 2896篇 |
2005年 | 2603篇 |
2004年 | 2190篇 |
2003年 | 1845篇 |
2002年 | 1714篇 |
2001年 | 1405篇 |
2000年 | 1186篇 |
1999年 | 873篇 |
1998年 | 681篇 |
1997年 | 648篇 |
1996年 | 745篇 |
1995年 | 634篇 |
1994年 | 659篇 |
1993年 | 628篇 |
1992年 | 660篇 |
1991年 | 479篇 |
1990年 | 488篇 |
1989年 | 438篇 |
1988年 | 394篇 |
1987年 | 402篇 |
1986年 | 360篇 |
1985年 | 564篇 |
1984年 | 560篇 |
1983年 | 445篇 |
1982年 | 474篇 |
1981年 | 462篇 |
1980年 | 461篇 |
1979年 | 436篇 |
1978年 | 428篇 |
1977年 | 439篇 |
1976年 | 401篇 |
1975年 | 389篇 |
1974年 | 382篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
Karakuş Erman Erdemir Eda Suna Garen Liv Lokman Gunduz Simay Can Şevval Arzu 《Journal of fluorescence》2021,31(6):1617-1625
Journal of Fluorescence - We have constructed a novel fluorescein-based fluorescent chemosensor, FL-In, functionalised with an indole moiety and capable of sensing by both the optical... 相似文献
2.
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
3.
4.
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
5.
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
6.
为提高煤与瓦斯突出矿井瓦斯抽放效果,建立了3个一级指标、14个二级指标的突出矿井瓦斯抽放限制影响因素评价指标体系,利用AHP和熵权法分别确定指标因子主、客观权重.通过实地调研分析和反馈验证了AHP-熵权法的可行性和正确性,利用加权平均法确定评价模型的综合权重.研究表明:封孔方式、钻孔半径、抽放时间、煤体裂隙发育程度和抽放负压是目前影响煤矿瓦斯抽放效果的主控因素. 相似文献
7.
Verdecho María-José Alarcón-Valero Faustino Pérez-Perales David Alfaro-Saiz Juan-José Rodríguez-Rodríguez Raúl 《Central European Journal of Operations Research》2021,29(4):1231-1251
Central European Journal of Operations Research - Sustainability practice within supply chains remains in an early development phase. Enterprises still need tools that support the integration of... 相似文献
8.
The Ramanujan Journal - We calculate the dimensions of the spaces of invariant vectors under the Klingen congruence subgroup of level $${\mathfrak {p}}^2$$ for all irreducible, admissible... 相似文献
9.
10.
Laurens Kooijman Dr. Matthias Schuster Christian Baumann Simon Jurt Dr. Frank Löhr Dr. Boris Fürtig Prof. Dr. Peter Güntert Prof. Dr. Oliver Zerbe 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(47):21151-21158
To achieve efficient proton pumping in the light-driven proton pump bacteriorhodopsin (bR), the protein must be tightly coupled to the retinal to rapidly convert retinal isomerization into protein structural rearrangements. Methyl group dynamics of bR embedded in lipid nanodiscs were determined in the dark-adapted state, and were found to be mostly well ordered at the cytosolic side. Methyl groups in the M145A mutant of bR, which displays only 10 % residual proton pumping activity, are less well ordered, suggesting a link between side-chain dynamics on the cytosolic side of the bR cavity and proton pumping activity. In addition, slow conformational exchange, attributed to low frequency motions of aromatic rings, was indirectly observed for residues on the extracellular side of the bR cavity. This may be related to reorganization of the water network. These observations provide a detailed picture of previously undescribed equilibrium dynamics on different time scales for ground-state bR. 相似文献