全文获取类型
收费全文 | 1071篇 |
免费 | 25篇 |
国内免费 | 9篇 |
专业分类
化学 | 815篇 |
晶体学 | 5篇 |
力学 | 49篇 |
数学 | 81篇 |
物理学 | 155篇 |
出版年
2023年 | 11篇 |
2022年 | 14篇 |
2021年 | 20篇 |
2020年 | 22篇 |
2019年 | 25篇 |
2018年 | 18篇 |
2017年 | 9篇 |
2016年 | 15篇 |
2015年 | 16篇 |
2014年 | 33篇 |
2013年 | 34篇 |
2012年 | 53篇 |
2011年 | 71篇 |
2010年 | 44篇 |
2009年 | 34篇 |
2008年 | 65篇 |
2007年 | 58篇 |
2006年 | 59篇 |
2005年 | 53篇 |
2004年 | 63篇 |
2003年 | 53篇 |
2002年 | 41篇 |
2001年 | 17篇 |
2000年 | 10篇 |
1999年 | 7篇 |
1998年 | 11篇 |
1997年 | 11篇 |
1996年 | 9篇 |
1995年 | 11篇 |
1994年 | 5篇 |
1993年 | 8篇 |
1992年 | 9篇 |
1990年 | 10篇 |
1989年 | 8篇 |
1987年 | 8篇 |
1986年 | 5篇 |
1985年 | 7篇 |
1984年 | 11篇 |
1982年 | 6篇 |
1980年 | 8篇 |
1979年 | 5篇 |
1978年 | 10篇 |
1977年 | 7篇 |
1975年 | 9篇 |
1973年 | 6篇 |
1972年 | 6篇 |
1970年 | 9篇 |
1969年 | 7篇 |
1968年 | 6篇 |
1967年 | 7篇 |
排序方式: 共有1105条查询结果,搜索用时 15 毫秒
51.
Alia Jouhara Eric Quarez Franck Dolhem Michel Armand Nicolas Dupr Philippe Poizot 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(44):15827-15831
The ever‐increasing demand for rechargeable batteries induces significant pressure on the worldwide metal supply, depleting resources and increasing costs and environmental concerns. In this context, developing the chemistry of anion‐inserting electrode organic materials could promote the fabrication of molecular (metal‐free) rechargeable batteries. However, few examples have been reported because little effort has been made to develop such anionic‐ion batteries. Here we show the design of two anionic host electrode materials based on the N‐substituted salts of azaaromatics (zwitterions). A combination of NMR, EDS, FTIR spectroscopies coupled with thermal analyses and single‐crystal XRD allowed a thorough structural and chemical characterization of the compounds. Thanks to a reversible electrochemical activity located at an average potential of 2.2 V vs. Li+/Li, the coupling with dilithium 2,5‐(dianilino)terephthalate (Li2DAnT) as the positive electrode enabled the fabrication of the first all‐organic anionic rechargeable batteries based on crystallized host electrode materials capable of delivering a specific capacity of ≈27 mAh/gelectrodes with a stable cycling over dozens of cycles (≈24 Wh/kgelectrodes). 相似文献
52.
Deschamps M Fayon F Cadars S Rollet AL Massiot D 《Physical chemistry chemical physics : PCCP》2011,13(17):8024-8030
Measuring internuclear distances through dipolar interaction is a major challenge for solid-state nuclear magnetic resonance (NMR) spectroscopy. Obtaining reliable interatomic distances provides an access to the local structure in ordered or disordered solids. We show that at magic angle spinning (MAS) frequencies larger than ca. 50 kHz, some of the three-spin terms of the homogeneous homonuclear dipolar Hamiltonian can be used to promote the creation of double-quantum coherences between neighbouring (1)H or (19)F spins without using dipolar recoupling pulse sequences in the Dipolar Homonuclear Homogeneous Hamiltonian (DH(3)) double-quantum/single-quantum correlation experiment. This makes it possible to probe inter-nuclear spatial proximity with limited risk of probe or sample damage from radio-frequency (RF) irradiation, and is fully appropriate for fast repetition rate offering sensitivity gains in favourable cases. Experimental demonstrations are supported by multi-spin numerical simulations, which points to new possibilities for the characterization of spin-system geometries. 相似文献
53.
54.
The short and efficient asymmetric synthesis of (-)-1-hydroxyquinolizidinone was achieved in seven steps and 25.2% overall yield from readily available 5-chloropentanal. It is a key intermediate in the formal syntheses of (-)-homopumilotoxin 223G and (-)-epiquinamide. 相似文献
55.
56.
In this study, through the method of rapid controlled precipitation (RCP), the influence of temperature and dissolved CO2 on the scaling capacity of mineral water in the presence of copper and zinc ions was studied in laboratory experiments. The
results indicated that with a rise in temperature or concentration of dissolved CO2, the scaling time of Salvetat water greatly decreased and the rate of precipitation considerably increased; therefore, the
minimum dosage of copper or zinc ion for achieving total inhibition of scaling needed to be increased, which would provide
better guidance for practical use of metal ions in inhibiting the scaling of drinking water. 相似文献
57.
58.
Here we describe the synthesis of a mesoporous composite material using the self-assembly of well defined tubular building blocks obtained from the exfoliation of [Nb6O17(4-)]n sheets. 相似文献
59.
Franck Leprévost 《manuscripta mathematica》1992,75(1):303-326
We construct here, forl=2g
2
+2g+1 or2g
2
+3g+1, a family with one parameter of hyperelliptic curves of genusg overQ such that its jacobian has a point of orderl rational overQ(t). Wheng=2 the method allows to construct, forl=17, 19 or 21 a family with one parameter of hyperelliptic curves of genus 2 overQ such that its jacobian has a point of orderl rational overQ(t).
相似文献
60.