全文获取类型
收费全文 | 74篇 |
免费 | 3篇 |
国内免费 | 6篇 |
专业分类
化学 | 63篇 |
综合类 | 1篇 |
数学 | 2篇 |
物理学 | 17篇 |
出版年
2022年 | 8篇 |
2021年 | 9篇 |
2020年 | 2篇 |
2019年 | 3篇 |
2018年 | 3篇 |
2017年 | 5篇 |
2016年 | 2篇 |
2015年 | 2篇 |
2014年 | 3篇 |
2013年 | 6篇 |
2012年 | 3篇 |
2011年 | 5篇 |
2010年 | 1篇 |
2009年 | 4篇 |
2008年 | 3篇 |
2007年 | 1篇 |
2006年 | 2篇 |
2005年 | 4篇 |
2004年 | 2篇 |
2002年 | 2篇 |
2001年 | 1篇 |
2000年 | 2篇 |
1998年 | 3篇 |
1997年 | 1篇 |
1996年 | 1篇 |
1995年 | 1篇 |
1991年 | 3篇 |
1978年 | 1篇 |
排序方式: 共有83条查询结果,搜索用时 15 毫秒
1.
A method is described for the simultaneous quantitative determination of monoamines and related compounds from urine and brain tissue samples in the pg-range, using a GC/MF instrument LKB-2091 provided with a multiple ion detection (MID) system and capillary columns. The simultaneous detection of “fingerprints” with fourteen and more compounds during one single GC run was achieved after the intoduction of “time gates” for the detection of the different characteristic masses. Several modifications to the LKB equipment permitted exact reproducibility of retention times, which is essential for the use of “time gates”. The detection of “fingerprints” with these acidic, basic and alcoholic substances was achieved by the extraction of the dried biological samples with silylating agents. 相似文献
2.
Oliveira SC Paiva TC Visconti AE Giudici R 《Applied biochemistry and biotechnology》1998,74(3):161-172
Discrimination between different rival models for describing the inhibitory effect of ethanol both on yeast growth and on
fermentation was studied for a continuous process of alcoholic fermentation in a tower reactor with recycling of flocculating
cells. Models tested include linear, parabolic, hyperbolic, exponential, and generalized nonlinear power-law types. The best
expressions were identified under the criteria that all the kinetic parameters should assume acceptable values in a feasible
range and should result in the best fit of the experimental data. The kinetic parameters were estimated from steady-state
data of several sugar concentrations in feeding stream (S0 = 160, 170, 180, 190, 200 g/L), constant dilution rate (D = 0.2 h-1), recycle ratio (α = 13.6), and temperature (T = 30°C). The best model for the yeast growth was of power-law type, whereas
for the product formation the best model was of linear type. These models were able to reproduce the trends of the process
variables satisfactorily. 相似文献
3.
Yulia B. Monakhova Svetlana P. Mushtakova Thomas Kuballa Dirk W. Lachenmeier 《Magnetic resonance in chemistry : MRC》2014,52(12):755-759
An eight‐fold suppression pulse sequence was recently developed to improve sensitivity in 1H NMR measurements of alcoholic beverages [Magn. Res. Chem. 2011 (49): 734–739]. To ensure that only one combined hydroxyl peak from water and ethanol appears in the spectrum, adjustment to a certain range of ethanol concentrations was required. To explain this observation, the structure of water–ethanol solutions was studied. Hydroalcoholic solutions showed extreme behavior at 25% vol, 46% vol, and 83% vol ethanol according to 1H NMR experiments. Near‐infrared spectroscopy confirmed the occurrence of four significant compounds (‘individual’ ethanol and water structures as well as two water–ethanol complexes of defined composition – 1 : 1 and 1 : 3). The successful multiple suppression can be achieved for every kind of alcoholic beverage with different alcoholic strengths, when the final ethanol concentration is adjusted to a range between 25% vol and 46% vol (e.g. using dilution or pure ethanol addition). In this optimum region, an individual ethanol peak was not detected, because the ‘individual’ water structure and the 1 : 1 ethanol–water complex predominate. The nature of molecular association in ethanol–water solutions is essential to elucidate NMR method development for measurement of alcoholic beverages. The presented approach can be used to optimize other NMR suppression protocols for binary water–organic solvent mixtures, where hydrogen bonding plays a dominant role. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
4.
5.
Muhammad Saleem Naseem Akhter Muhammad Shaiq Ali Mamona Nazir Naheed Riaz Muhammad Moazzam Muhammad Arshad Abdul Jabbar 《Magnetic resonance in chemistry : MRC》2009,47(3):263-265
Chromatographic analysis of the alcoholic extract from Salsola imbricata yielded two new secondary metabolites, salisomide (1) and salisoflavan (2). Their structures were established with the help of spectroscopic techniques including COSY, HMQC and HMBC NMR experiments. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
6.
Advanced solvent signal suppression for the acquisition of 1D and 2D NMR spectra of Scotch Whisky
下载免费PDF全文
![点击此处可从《Magnetic resonance in chemistry : MRC》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Will Kew Nicholle G.A. Bell Ian Goodall Dušan Uhrín 《Magnetic resonance in chemistry : MRC》2017,55(9):785-796
A simple and robust solvent suppression technique that enables acquisition of high‐quality 1D 1H nuclear magnetic resonance (NMR) spectra of alcoholic beverages on cryoprobe instruments was developed and applied to acquire NMR spectra of Scotch Whisky. The method uses 3 channels to suppress signals of water and ethanol, including those of 13C satellites of ethanol. It is executed in automation allowing high throughput investigations of alcoholic beverages. On the basis of the well‐established 1D nuclear Overhauser spectroscopy (NOESY) solvent suppression technique, this method suppresses the solvent at the beginning of the pulse sequence, producing pure phase signals minimally affected by the relaxation. The developed solvent suppression procedure was integrated into several homocorrelated and heterocorrelated 2D NMR experiments, including 2D correlation spectroscopy (COSY), 2D total correlation spectroscopy (TOCSY), 2D band‐selective TOCSY, 2D J‐resolved spectroscopy, 2D 1H, 13C heteronuclear single‐quantum correlation spectroscopy (HSQC), 2D 1H, 13C HSQC‐TOCSY, and 2D 1H, 13C heteronuclear multiple‐bond correlation spectroscopy (HMBC). A 1D chemical‐shift‐selective TOCSY experiments was also modified. The wealth of information obtained by these experiments will assist in NMR structure elucidation of Scotch Whisky congeners and generally the composition of alcoholic beverages at the molecular level. 相似文献
7.
目的评价冠状动脉造影的形态学特征对经皮室间隔心肌化学消融(PTSMA)术治疗肥厚型梗阻性心肌病(HOCM)的指导意义.方法选择32例药物疗效欠佳并行PTSMA手术的HOCM患者,研究其冠状动脉造影特点,并与30例年龄、性别相匹配的冠状动脉造影正常的患者(对照组)进行比较.根据定量冠状动脉造影(QCA)测定目标消融间隔支的直径,分为≤1.5mm(小间隔支组)和>1.5mm组(大间隔支组),比较两组PTSMA术前、术后心导管测量左心室流出道压差(LVOTG)的变化.结果冠状动脉造影显示HOCM组的左主干、左前降支、左回旋支及左间隔支内径均显著大于对照组(均P<0.05),HOCM组左前降支肌桥的发生率较对照组亦明显增加(P<0.05);23例消融成功,PTSMA术前、术后导管测量LVOTG分别为(85.8±31.1)、(37.25±31.9)mmHg(P<0.01),其中大间隔支组PTSMA成功率明显高于小间隔支组(P<0.05),大间隔支组LVOTG的下降程度明显大于小间隔支组(P<0.05),两组间无水乙醇用量差异无统计学意义(P>0.05).结论 HOCM患者的左前降支肌桥发生率增加,且左冠状动脉内径较粗大,尤其是左间隔支粗大;间隔支>1.5mm的HOCM患者是PTSMA手术成功的重要预测因素,这对PTSMA目标消融间隔支的选择具有重要指导意义. 相似文献
8.
Buse C Altmann F Amann B Hauck SM Poulsen Nautrup C Ueffing M Stangassinger M Deeg CA 《Electrophoresis》2008,29(6):1325-1332
There is increasing evidence that a large proportion of dilated cardiomyopathy (DCM) cases are mediated by autoimmune processes. Since DCM is a fatal disorder with rapid aggravation and is the leading cause of heart transplantation, further insights into disease pathogenesis are needed. Recent studies have separated the pathogenic capacity of autoantibodies and initial clinical trials removing such autoantibodies via immunoadsorption have been promising. In order to elucidate the full autoantibody repertoire involved in DCM, we applied an autoantibody screening test using ventricular and atrial proteomes as autoantigenic sources and subsequently tested the autoantibody-binding patterns of sera from dogs with spontaneous DCM. With this method, we detected five potentially DCM-related autoantigens which were identified by MS as being: myosin heavy chain cardiac muscle alpha isoform, alpha cardiac actin, mitochondrial aconitate hydratase, glyceraldehyde-3-phosphate dehydrogenase (GAPDH), and brain glycogen phosphorylase (GPBB). The recovery of two known DCM autoantigens (myosin heavy chain and alpha cardiac actin) and the discovery of three novel autoantigens (mitochondrial aconitate hydratase, GADPH, and GPBB) underscore the efficacy of this experimental method and the significance of the spontaneous canine DCM model. 相似文献
9.
牛丽芳 《原子与分子物理学报》2017,34(6)
采用Materials Studio8.0软件中的DMol3程序对醇类化合物热值改进剂的几何结构和性质(振动频率、反应活性、热力学及稳定性)进行了理论研究,得到了分子稳定的几何构型、各原子上的电荷分布、热力学性质、Fukui指数和前沿分子轨道能级。计算结果表明:醇类化合物热值改进剂分子结构中的1个-OH是影响其抗氧化活性的主要部位和亲电反应发生的活性位点,整体表现为比较理想的稳定性能。 相似文献
10.
Ning Ma Huaibing Cheng Minjie Lu Shiliang Jiang Gang Yin Shihua Zhao 《Magnetic resonance imaging》2012
The aim of the study was to evaluate the relationship between the presence of right ventricular abnormalities detected by cardiac magnetic resonance (CMR) and QRS dispersion, the strongest independent predictor of sudden death in ARVC. A consecutive series of 40 patients from a single institution were recruited with a clinical diagnosis of ARVC based on the diagnostic criteria. All patients underwent systematic clinical evaluation, including history and examination, electrocardiography, 24-h Holter monitor, chest radiography, echocardiography and CMR examination and were divided into two groups according to the QRS dispersion: group I, QRS dispersion ≥ 40 ms; group II, QRS dispersion < 40 ms. The relationship between the characteristic parameters of CMR image and QRS dispersion were analyzed in two groups. There were significant differences in QRS dispersion (57±14 ms vs. 26±11 ms), right ventricular end-diastolic diameter (57±10 mm vs. 48±11 mm, P=.012), right ventricular end-systolic diameter (52±10 mm vs. 44±11 mm, P=.010), right ventricular end-diastolic volume (260±105 ml vs. 180±66 ml, P=.006), right ventricular end-systolic volume (222±98 ml vs. 148±61 ml, P=.006) and myocardial fibrosis detection rate (74% vs. 38%, P=.024) between two groups. For all patients with ARVC, QRS dispersion and right ventricular end-diastolic volume (r= 0.66, P<.001), right ventricular end-systolic volume (r= 0.67, P<.001), right ventricular outflow tract area (r= 0.68, P<.001) showed a moderate positive correlation. Right ventricular outflow tract area, right ventricular end-diastolic volume and end-systolic volume detected by CMR in patients with ARVC were positively correlated to the extent of QRS dispersion (≥ 40 ms), the strongest independent predictor of sudden cardiac death. 相似文献