全文获取类型
收费全文 | 220篇 |
免费 | 6篇 |
专业分类
化学 | 172篇 |
晶体学 | 6篇 |
力学 | 2篇 |
数学 | 24篇 |
物理学 | 22篇 |
出版年
2022年 | 2篇 |
2020年 | 3篇 |
2016年 | 7篇 |
2015年 | 5篇 |
2014年 | 4篇 |
2013年 | 16篇 |
2012年 | 19篇 |
2011年 | 20篇 |
2010年 | 8篇 |
2009年 | 10篇 |
2008年 | 12篇 |
2007年 | 11篇 |
2006年 | 12篇 |
2005年 | 5篇 |
2004年 | 8篇 |
2003年 | 4篇 |
2002年 | 17篇 |
2001年 | 3篇 |
1999年 | 2篇 |
1997年 | 4篇 |
1995年 | 2篇 |
1993年 | 1篇 |
1992年 | 1篇 |
1990年 | 2篇 |
1989年 | 2篇 |
1987年 | 2篇 |
1985年 | 4篇 |
1984年 | 2篇 |
1983年 | 1篇 |
1982年 | 5篇 |
1980年 | 3篇 |
1979年 | 1篇 |
1978年 | 3篇 |
1977年 | 1篇 |
1974年 | 1篇 |
1973年 | 1篇 |
1972年 | 1篇 |
1971年 | 1篇 |
1964年 | 1篇 |
1961年 | 1篇 |
1960年 | 1篇 |
1952年 | 1篇 |
1941年 | 1篇 |
1935年 | 2篇 |
1930年 | 2篇 |
1929年 | 1篇 |
1928年 | 1篇 |
1925年 | 1篇 |
1919年 | 1篇 |
1913年 | 1篇 |
排序方式: 共有226条查询结果,搜索用时 15 毫秒
11.
Mantz YA Gerard H Iftimie R Martyna GJ 《Journal of the American Chemical Society》2004,126(13):4080-4081
The cis-trans isomerization of N-methylacetamide, a molecular model of the polypeptide chain, is examined via umbrella sampling Car-Parrinello MD and classical MD, in both gas and solution phases at 300 K. A new analysis of the C(O)-N bond interconversion and a full examination of the solvent shell structure are presented. 相似文献
12.
A microfluidic approach for rapid bioluminescent real-time detection of single nucleotide polymorphism (SNP) is presented. The method is based on single-step primer extension using pyrosequencing chemistry to monitor nucleotide incorporations in real-time. The method takes advantage of the fact that the reaction kinetics differ between matched and mismatched primer-template configurations. We show here that monitoring the initial reaction in real time accurately scores SNPs by comparing the initial reaction kinetics between matched and mismatched configurations. Thus, no additional treatment is required to improve the sequence specificity of the extension, which has been the case for many allele-specific extension assays. The microfluidic approach was evaluated using four SNPs. Three of the SNPs included primer-template configurations that have been previously reported to be difficult to resolve by allele-specific primer extension. All SNPs investigated were successfully scored. Using the microfluidic device, the volume for the bioluminescent assay was reduced dramatically, thus offering a cost-effective and fast SNP analysis method. 相似文献
13.
14.
15.
16.
Ohne Zusammenfassung 相似文献
17.
Marie Kjærgaard Bjørk Marie K. K. Nielsen Lotte Ø. Markussen Helene B. Klinke Kristian Linnet 《Analytical and bioanalytical chemistry》2010,396(7):2393-2401
A high-performance liquid chromatography (LC)–tandem mass spectrometry (MS/MS) method has been developed and validated for
the determination of 19 drugs of abuse and metabolites and used in whole blood. The following compounds were included: amphetamine,
methylenedioxyamphetamine, methylenedioxyethylamphetamine, methylenedioxymethamphetamine, methamphetamine, cocaine, benzoylecgonine,
morphine, 6-acetylmorphine, codeine, methadone, buprenorphine, norbuprenorphine, ketobemidone, tramadol, O-desmethyltramadol, zaleplone, zolpidem, and zopiclone. The sample pretreatment consisted of solid-phase extraction using
mixed-mode columns (Isolute Confirm HCX). Deuterated analogues were used as internal standards for all analytes, except for
ketobemidone and O-desmethyltramadol. The analytes were separated by a methanol/ammonium formate gradient using high-performance LC (Agilent
HPLC 1100) with a 3 mm × 100 mm Varian Pursuit 3 C18 column, 3-μm particle size, and were quantified by MS/MS (Waters Quattro micro tandem quadrupole mass spectrometer) using
multiple reaction monitoring in positive mode. Two transitions were used for all analytes, except for tramadol and O-desmethyltramadol. The run time of the method was 35 min including the equilibration time. For all analytes, responses were
linear over the range investigated, with R
2 > 0.99. One-point calibration was found to be adequate by validation, thereby saving analysis of multiple calibrators. The
limits of quantification (LOQs) for the analytes ranged from 0.0005 to 0.01 mg/kg. Absolute recoveries of the analytes were
from 34 to 97%, except for zaleplone (6%). Both the interday precision and the intraday precision were less than 15% (20%
at the LOQ) for all analytes, except buprenorphine, norburprenorphine, and zaleplone (less than 18%). Accuracy (bias) was
within ±15% (±20% at the LOQ) for all analytes, except MDMA and O-desmethyltramadol (within ±19%). No ion suppression or enhancement was seen nor was suppression from coeluted analytes seen.
Matrix effects were found to be less than 23% for all analytes, except zopiclone (64%). High-concentration and low-concentration
quality control samples gave acceptable values, and the method has been tried in international proficiency test schemes with
good results. The present LC-MS/MS method provides a simple, specific, and sensitive solution for the quantification of some
of the most frequent drugs of abuse and their metabolites in whole blood. The quantification by LC-MS/MS was successfully
applied to 412 forensic cases from October 2008 to mid February 2009, where 267 cases were related to zero-tolerance traffic
legislation. 相似文献
18.
19.
20.