全文获取类型
收费全文 | 692篇 |
免费 | 18篇 |
国内免费 | 9篇 |
专业分类
化学 | 475篇 |
晶体学 | 8篇 |
力学 | 12篇 |
数学 | 76篇 |
物理学 | 148篇 |
出版年
2022年 | 7篇 |
2021年 | 5篇 |
2020年 | 10篇 |
2019年 | 9篇 |
2018年 | 8篇 |
2017年 | 4篇 |
2016年 | 11篇 |
2015年 | 12篇 |
2014年 | 13篇 |
2013年 | 35篇 |
2012年 | 41篇 |
2011年 | 52篇 |
2010年 | 32篇 |
2009年 | 12篇 |
2008年 | 25篇 |
2007年 | 41篇 |
2006年 | 33篇 |
2005年 | 46篇 |
2004年 | 22篇 |
2003年 | 27篇 |
2002年 | 28篇 |
2001年 | 13篇 |
2000年 | 18篇 |
1999年 | 6篇 |
1998年 | 9篇 |
1997年 | 5篇 |
1996年 | 9篇 |
1995年 | 6篇 |
1994年 | 7篇 |
1993年 | 6篇 |
1992年 | 8篇 |
1991年 | 6篇 |
1990年 | 8篇 |
1989年 | 8篇 |
1988年 | 7篇 |
1987年 | 5篇 |
1986年 | 11篇 |
1985年 | 15篇 |
1984年 | 7篇 |
1983年 | 4篇 |
1982年 | 8篇 |
1981年 | 7篇 |
1976年 | 4篇 |
1975年 | 7篇 |
1974年 | 4篇 |
1973年 | 12篇 |
1972年 | 3篇 |
1969年 | 7篇 |
1968年 | 4篇 |
1943年 | 3篇 |
排序方式: 共有719条查询结果,搜索用时 62 毫秒
711.
Stevenson S Harich K Yu H Stephen RR Heaps D Coumbe C Phillips JP 《Journal of the American Chemical Society》2006,128(27):8829-8835
Separation difficulties have led to a paucity of purified metallic nitride fullerenes (MNFs). Fundamental research and application development has been hampered with limited sample availability. Separation techniques designed to remove contaminant empty-cage fullerenes (e.g., C(60), C(70)...C(2)(n)) and classical metallofullerenes (e.g., non-MNFs) traditionally require expensive and tedious chromatographic methods. Our motivation is an alternative purification approach to minimize dependence on HPLC. Herein we report the use of cyclopentadienyl (CPD) and amino functionalized silica to selectively bind contaminant fullerenes. This "Stir and Filter Approach" (SAFA) provides purified MNF samples at ambient and reflux conditions. Under reflux conditions, purified MNFs (80% recovery, 41 h) are obtained using CPD silica. However, at room temperature, there is an equilibrium established between fullerenes and CPD silica, and no purified MNF samples are obtained using SAFA. In contrast, purified MNF samples (99+%) are readily obtained at room temperature using amino, diamino, and triamino silica at recoveries of 93% (11 h), 76% (9 h), and 50% (6 h), respectively. 相似文献
712.
Surendra Barpete Priyanka Gupta Debjyoti Sen Gupta Jitendra Kumar Arpan Bhowmik Shiv Kumar 《Molecules (Basel, Switzerland)》2022,27(12)
ODAP (N-oxalyl-L-2,3-diaminopropionic acid) is present in the seeds of grass pea. In this study, variation of total ODAP accumulation in leaves throughout the crop growth starting from 40 days after sowing to maturity, and the distribution pattern of ODAP in different plant parts including the seeds at the mature stage was analyzed. Five grass pea accessions were evaluated for two subsequent growing seasons in one location of ICARDA, Aleppo (Syria). The results found that the rate of accumulation of total ODAP varied during plant development. Increased rates of synthesis were noticed in young leaves of grass pea. The highest total ODAP content in leaves was noted in the early growth stage (40–50 days after sowing). Mean total ODAP content in leaves ranged from 0.17 to 0.96 percent during 2010–2011 and from 0.19 to 1.28 percent during 2011–2012. During maturity, the total ODAP content was lowest in the seeds than in leaves, stems, pod cover, seed coat, and cotyledons. The ranges of total ODAP content were 0.13 (seed)–0.34 (stem), 0.20 (seed)–1.01 (leaf), 0.22 (seed)–0.62 (leaf), 0.21 (seed)–0.66 (leaf), and 0.21 (seed)–0.78 (leaf) percent in B387, B222, B390, Bio-520, and B587 accessions, respectively, during maturity. The results indicated that the rate of accumulation and synthesis of total ODAP varied during the plant lifespan. The lowest total ODAP content of leaves was observed after 130 days of sowing. The lower total ODAP content after the early vegetative stage of grass pea plants makes them suitable as a feed. 相似文献
713.
714.
715.
716.
717.
Isoscalar monopole strength in 100Mo: an indicator for static triaxial deformation in the ground state
下载免费PDF全文
![点击此处可从《中国物理C(英文版)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
We perform deformation constraint symmetry-unrestricted three-dimensional time-dependent density functional theory (TDDFT) calculations for the isoscalar monopole (ISM) mode in 100Mo. Monopole moments are obtained as a function of time using time propagating states based on different deformations. A Fourier transform is then performed on the obtained response functions. The resulting ISM strength functions are compared with experimental data. For the static potential-energy-surface (PES) calculations, the results using the SkM* and UNEDF1 energy-density functionals (EDFs) show spherical ground states and considerable softness in the triaxial deformation. The PES obtained with the SLy4 EDF shows static triaxial deformation. The TDDFT results based on different deformations show that a quadrupole deformation (characterized by \begin{document}$ \beta_2 $\end{document} ![]()
![]()
) value of 0.25–0.30 gives a two-peak structure of the strength functions. Increasing triaxial deformation (characterized by γ) from 0\begin{document}$ ^{\circ} $\end{document} ![]()
![]()
to 30\begin{document}$ ^{\circ} $\end{document} ![]()
![]()
results in the occurrence of an additional peak between the two, making the general shape of the strength functions closer to that of the data. Our microscopic TDDFT analyses suggest that 100Mo is triaxially deformed in the ground state. The calculated isoscalar \begin{document}$ Q_{20} $\end{document} ![]()
![]()
and \begin{document}$ Q_{22} $\end{document} ![]()
![]()
strength functions show peaks at lower energies. The coupling of these two modes with the ISM mode is the reason for the three-peak/plateau structure in the strengths of 100Mo. 相似文献
718.
719.
J. Ulises Reveles Patrizia Calaminici Marcela R. Beltran Andres M. Koester Shiv N. Khanna 《ChemInform》2008,39(16):no-no
ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option. 相似文献