全文获取类型
收费全文 | 151篇 |
免费 | 5篇 |
专业分类
化学 | 108篇 |
晶体学 | 6篇 |
力学 | 3篇 |
数学 | 12篇 |
物理学 | 27篇 |
出版年
2022年 | 1篇 |
2021年 | 5篇 |
2020年 | 3篇 |
2019年 | 3篇 |
2017年 | 2篇 |
2016年 | 2篇 |
2015年 | 4篇 |
2014年 | 4篇 |
2013年 | 3篇 |
2012年 | 9篇 |
2011年 | 10篇 |
2010年 | 6篇 |
2009年 | 4篇 |
2008年 | 7篇 |
2007年 | 9篇 |
2006年 | 9篇 |
2005年 | 6篇 |
2004年 | 8篇 |
2003年 | 3篇 |
2002年 | 13篇 |
2001年 | 3篇 |
2000年 | 1篇 |
1999年 | 1篇 |
1998年 | 3篇 |
1997年 | 2篇 |
1996年 | 6篇 |
1994年 | 2篇 |
1993年 | 1篇 |
1992年 | 1篇 |
1990年 | 3篇 |
1989年 | 4篇 |
1988年 | 1篇 |
1986年 | 1篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1982年 | 2篇 |
1981年 | 4篇 |
1979年 | 4篇 |
1977年 | 1篇 |
1976年 | 1篇 |
1972年 | 1篇 |
1939年 | 1篇 |
排序方式: 共有156条查询结果,搜索用时 31 毫秒
131.
Samia Yahyaoui Rached Ben Hassen Vaclav Petí
ek Michal Duek Abdelhamid Ben Salah 《Acta Crystallographica. Section C, Structural Chemistry》2003,59(3):i24-i26
The ternary system SrBr2–CdBr2–H2O was investigated at room temperature. The title phase, SrCd2Br6·8H2O, has been isolated from this system and its structure determined by single‐crystal X‐ray diffraction. The structure consists of infinite double chains of CdBr6 octahedra and chains of Sr(H2O)9 polyhedra packed along the b axis. The interaction between these two isolated chains occurs through O—H⃛O and O—H⃛Br hydrogen bonds. The structure is compared with that of SrCd2Cl6·8H2O. 相似文献
132.
The method is based on catalysed ignition of a sample portion in a flow of oxygen, capture of mercury by an amalgamator and
measurement of the mercury vapour's absorbance after thermic release from the amalgamator. Three powdered food samples, a
certified reference material (CRM) human hair and a reference material (RM) urine (liquid) were measured in the first range
of the instrument (the possible contents determined according to our measurement procedure were 0.0003–0.5 ppm). The calibration
function used was a line passing through the origin. The combined standard uncertainties of the mercury determinations were
computed from uncertainty components of five quantities: absorbance of the sample, absorbance of the sample blank, slope of
the calibration line, correction factor of the abscissa axis, and mass or volume of the sample. The most important uncertainty
component is the uncertainty of the sample absorbance measurement which amounts to 52% of the determination uncertainty at
the minimum (RM urine) and about 90% at the maximum (in our laboratory homogenized powdered food samples; analysis of variance
showed their homogeneity to be insufficient). The results of the CRM and RM analyses do not indicate a significant systematic
error for this determination. The relative expanded uncertainty (coefficient was 2) of the determination increases from 9
to 13% for the insufficiently homogenized samples with decreasing mercury content (range of 0.004–0.03 ppm); higher homogeneity
of samples results in a decrease of the expanded uncertainty, e.g. 4.6% for the liquid sample (RM urine).
Received: 26 April 1999 / Accepted: 30 August 1999 相似文献
133.
134.
Received: 4 June 1997/Accepted: 13 June 1997 相似文献
135.
Mondello L Tranchida PQ Stanek V Jandera P Dugo G Dugo P 《Journal of chromatography. A》2005,1086(1-2):91-98
The triacylglycerol (TAG) profiles present in real world lipidic samples are usually quite complex and, as such, monodimensional high-performance liquid chromatographic (HPLC) techniques are inadequate when challenged with such matrices. In this respect, the complementary use of silver-ion (Ag) and non-aqueous (NA) reversed-phase (RP) HPLC can be exploited if thorough TAG separations are required. The present investigation reports the employment of a newly developed comprehensive LC (LC x LC) system, based on the different separation mechanisms of the aforementioned techniques, and applied to a rice oil sample. The approach was successful in the separation of a high number of solutes, otherwise unachievable through monodimensional LC. Furthermore, the use of atmospheric pressure chemical ionization mass spectrometry (APCI-MS), as detection system, provided a third analytical dimension boosting the identification power of the comprehensive chromatographic method. 相似文献
136.
Acylation of each primary group of spermidine with cholic acid, followed by acylation of the secondary amino group using an activated form of Nalpha,Ndelta,Nomega-tri-CBZ-l-arginine, and subsequent hydrogenolysis, afforded a conjugate (i.e., 1) which readily transports adenosine 5-triphosphate, but not glutathione, across phospholipid bilayers made from 1-palmitoyl-2-oleyol-sn-glycero-3-phosphocholine and 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphatidylglycerol. 相似文献
137.
A novel analysis of explosives via the coupling of an airline passenger personnel portal with a high-flow (HF), high-resolution (HR) ion mobility spectrometry (IMS) was shown for the first time. The HF-HR-IMS utilized a novel ion aperture grid design with a (63)Ni ionization source while operating at ambient pressure in the positive ion mode at 200 degrees C. The HF-HR-IMS response characteristics of 2,4,6-trinitrotoluene (TNT), 4,6-dinitro-o-cresol (4,6DNOC), and cyclo-1,3,5-trimethylene-2,4,6-trinitramine (RDX) were investigated. Modifications made to the HF-HR-IMS exhaust and ionization source created an 800% increase in the total ion current (TIC), from 0.85 to 6.8 nA. This translated into a 65% ion response increase for TNT when compared with a traditional IMS. A mixture of TNT and (4,6DNOC) was used to successfully demonstrate the resolving power of the species with similar reduced mobility constants (K(o)), 1.54 and 1.59, respectively. The reactant ion (H(2)O)(n)H(+), peak was also used to measure the resolving power of the spectrometer while varying the internal diameter of three different aperture openings from 1.00 to 3.54cm. This provided a resolving power range of 50-60, double that typically achievable by commercial IMS instruments. Most important, these changes made in this new instrumental design can be implemented to all existing and future IMS's to greatly enhance the achievable IMS resolving power. 相似文献
138.
A series of molecular umbrella conjugates, derived from cholic acid, deoxycholic acid, spermidine, lysine, and 5-mercapto-2-nitrobenzoic acid, have been synthesized and found capable of transporting an attached 16-mer oligonucleotide (S-dT16) across liposomal membranes made from 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC), 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphatidyldglycerol (POPG), and cholesterol [POPC/POPG/cholesterol (65/5/30; mol/mol/mol, v/v/v)] at 37 degrees C. Those molecular umbrellas containing four choloyl (or deoxycholoyl) groups resulted in significantly faster rates of transport as compared to those containing only two such moieties. A model that accounts for these membrane transport processes is proposed. 相似文献
139.
J. D'Ans K. Wagenmann Richard Berg K. R. Andreß G. Rienäcker J. Heyrovskv G. Mann K. Wüst G. Hesse M. Haitinger A. Winkel H. Siebert A. A. Benedetti-Pichler H. Lieb F. Löwe W. Meidinger Verein Deutscher Ingenieure W. Matz E. Wicke Hermann Mayer 《Analytical and bioanalytical chemistry》1939,117(3-4):157-158
140.