全文获取类型
收费全文 | 11429篇 |
免费 | 374篇 |
国内免费 | 17篇 |
专业分类
化学 | 6165篇 |
晶体学 | 81篇 |
力学 | 311篇 |
数学 | 2469篇 |
物理学 | 2794篇 |
出版年
2022年 | 135篇 |
2021年 | 166篇 |
2020年 | 151篇 |
2019年 | 180篇 |
2018年 | 196篇 |
2017年 | 214篇 |
2016年 | 435篇 |
2015年 | 388篇 |
2014年 | 411篇 |
2013年 | 777篇 |
2012年 | 581篇 |
2011年 | 679篇 |
2010年 | 409篇 |
2009年 | 355篇 |
2008年 | 470篇 |
2007年 | 406篇 |
2006年 | 364篇 |
2005年 | 244篇 |
2004年 | 236篇 |
2003年 | 253篇 |
2002年 | 212篇 |
2001年 | 164篇 |
2000年 | 171篇 |
1999年 | 158篇 |
1998年 | 141篇 |
1997年 | 133篇 |
1996年 | 134篇 |
1995年 | 120篇 |
1994年 | 120篇 |
1993年 | 121篇 |
1992年 | 114篇 |
1991年 | 90篇 |
1990年 | 107篇 |
1989年 | 92篇 |
1988年 | 94篇 |
1987年 | 91篇 |
1986年 | 83篇 |
1985年 | 137篇 |
1984年 | 142篇 |
1983年 | 111篇 |
1982年 | 117篇 |
1981年 | 116篇 |
1980年 | 111篇 |
1979年 | 120篇 |
1978年 | 101篇 |
1977年 | 102篇 |
1976年 | 118篇 |
1975年 | 111篇 |
1974年 | 104篇 |
1973年 | 86篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
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
2.
Zakrajšek Srečko Rajkovič Vladislav Bernik Mojca Jereb Eva Rajkovič Uroš 《Central European Journal of Operations Research》2021,29(3):841-857
Central European Journal of Operations Research - Digital competences are among the most important competences in modern society, with the education system playing a key role in the acquisition of... 相似文献
3.
4.
5.
6.
Nováková Kateřina Hrdlička Vojtěch Navrátil Tomáš Vyskočil Vlastimil Barek Jiří 《Monatshefte für Chemie / Chemical Monthly》2015,146(5):761-769
Monatshefte für Chemie - Chemical Monthly - The voltammetric behavior of 5-nitroindazole was investigated at polished (p-AgSAE) and at mercury meniscus-modified (m-AgSAE) silver solid amalgam... 相似文献
7.
8.
9.
Vanessa R. Machado Louis P. Sandjo Giovanni L. Pinheiro Milene H. Moraes Mario Steindel Moacir G. Pizzolatti 《Natural product research》2018,32(3):275-281
The natural product lupeol 1 was isolated from aerial parts of Vernonia scorpioides with satisfactory yield, which made it viable to be used as starting material in semisynthetic approach. Ten lupeol derivatives 2–11 were prepared by classical procedures. Including, five new esters derivatives 7–11, which were obtained by structural modifications in the isopropylidene fragment. All semisynthetic compounds and lupeol 1–11 were confirmed by 1H NMR, 13C NMR and HRMS. Their antiprotozoal activity was evaluated in vitro against L. amazonensis and T. cruzi. Derivative 6 showed the best antitrypanosomal activity (IC50 = 12.48 μg/mL) and the lowest cytotoxic derivative (CC50 = 161.50 μg/mL). The mechanism of action of the most active derivatives (4, 6 and 11) is not dependent from the enzyme trypanothione reductase. 相似文献
10.
Separation of 23 dansylated amino acids by micellar electrokinetic chromatography at low temperature
Summary The baseline separation of 23 dansylated amino acids (including 3 didansylated species) is reported. Lowering of the analysis
temperature and fine control of the surfactant concentration were essential in obtaining this result. Calibration graphs with
good linearity were obtained. 相似文献