全文获取类型
收费全文 | 1193篇 |
免费 | 31篇 |
国内免费 | 11篇 |
专业分类
化学 | 742篇 |
晶体学 | 7篇 |
力学 | 9篇 |
数学 | 90篇 |
物理学 | 387篇 |
出版年
2022年 | 10篇 |
2021年 | 11篇 |
2020年 | 14篇 |
2019年 | 12篇 |
2018年 | 7篇 |
2017年 | 8篇 |
2016年 | 22篇 |
2015年 | 23篇 |
2014年 | 22篇 |
2013年 | 45篇 |
2012年 | 72篇 |
2011年 | 62篇 |
2010年 | 48篇 |
2009年 | 65篇 |
2008年 | 62篇 |
2007年 | 61篇 |
2006年 | 60篇 |
2005年 | 56篇 |
2004年 | 44篇 |
2003年 | 40篇 |
2002年 | 49篇 |
2001年 | 35篇 |
2000年 | 38篇 |
1999年 | 12篇 |
1998年 | 17篇 |
1997年 | 13篇 |
1996年 | 19篇 |
1995年 | 18篇 |
1994年 | 24篇 |
1993年 | 9篇 |
1992年 | 12篇 |
1990年 | 9篇 |
1989年 | 14篇 |
1988年 | 16篇 |
1987年 | 12篇 |
1986年 | 10篇 |
1985年 | 23篇 |
1984年 | 10篇 |
1983年 | 11篇 |
1982年 | 8篇 |
1981年 | 12篇 |
1980年 | 6篇 |
1979年 | 12篇 |
1978年 | 9篇 |
1977年 | 6篇 |
1976年 | 7篇 |
1975年 | 9篇 |
1974年 | 8篇 |
1973年 | 9篇 |
1972年 | 13篇 |
排序方式: 共有1235条查询结果,搜索用时 15 毫秒
21.
Michael A. Luzuriaga Candace E. Benjamin Michael W. Gaertner Hamilton Lee Fabian C. Herbert Snipta Mallick 《Supramolecular chemistry》2019,31(8):485-490
ABSTRACTDrug delivery using metal-organic frameworks (MOF) has elicited interest in their biocompatibility; however, few studies have been conducted on their stability in common buffers, cell media, and blood proteins. In particular, the use of ZIF-8, a MOF interconnected by Zn and methylimidazole, has been frequently employed. In this study, we tested single crystals of ZIF-8 with common laboratory buffers, cell media, and serum, and noted several issues. Buffers containing phosphate and bicarbonate alter the appearance and composition of ZIF-8; however, these buffers do not appear to cause cargo to leak out even when the ZIF-8 itself is displaced by phosphates. On the other hand, serum dissolves ZIF-8, causing premature cargo release. Our results show that ZIF-8 undergoes surface chemistry changes that may affect the interpretation of cellular uptake and cargo release data. On the other hand, it provides a rational explanation as to how ZIF-8 neatly dissolves in vivo. 相似文献
22.
The method of analysis for sulfate by reduction of high oxidation state sulfur to hydrogen sulfide, followed by spectrophotometric analysis, has the advantages of allowing small quantities to be measured and some interfering species to be removed. However, it has been found that acid digested samples cannot be analysed by this method due to destruction of the reduction mixture. A column of zirconium(IV) oxide was successfully used to both, remove interfering ions (H(+), Cl(-) and NO(-)(3)) from a sediment digest, as well as perform preconcentration of sulfate. Recoveries from digests of standard sulfur samples were 101 +/- 1%, and from preconcentration solutions 98.8 +/- 1.2%. Comparison of results with independent analyses confirmed that not all sulfur species are detected with the same efficiency by the combined zirconia/reduction-spectrophotometric method. 相似文献
23.
24.
25.
Maria do Carmo Rangel Varela Milton Francisco de Jesus Filho Fernando Galembeck 《Hyperfine Interactions》1994,83(1):159-167
Mössbauer spectroscopy was used to follow the aging of ferrihydrite with different amounts of acetate, to achieve more crystalline products. Mössbauer spectra of fresh samples did not show any magnetic components. After two years aging, the solids presented crystalline fractions. Hematite formation was inhibited as acetate content increased in solids. For an acetate/iron molar ratio equal to 0.63 goethite was formed instead of hematite. X-ray diffraction confirmed these results. This work shows that synthetic samples can be used for elucidating the anti-hematitic effect of organic matter already detected in soils. 相似文献
26.
27.
LetA be a von Neumann algebra and a faithful normal state. ThenO
= {
ºAd(g
1) :g G
A
}andU
= {
ºAd(u
*) :u U
A
are homogeneous reductive spaces. IfA is aC
* algebra,e
the Jones projection of the faithful state viewed as a conditional expectation, then we prove that the similarity orbit ofe
by invertible elements ofA can be imbedded inAA in such a way thate
is carried to 1 1 and the orbit ofe
to a homogeneous reductive space and an analytic submanifold ofAA. 相似文献
28.
29.
30.
Yong‐Qian Wu David C. Limburg Douglas E. Wilkinson Gregory S. Hamilton 《Journal of heterocyclic chemistry》2003,40(1):191-193
A mild and efficient synthesis of five‐ and six‐membered nitrogen containing heterocyclic compounds, in which di(imidazole‐1‐yl)methanimine serves as a one‐carbon source, is reported. 相似文献