نتایج جستجو برای: chemical element

تعداد نتایج: 575159  

Journal: :Proceedings of the National Academy of Sciences of the United States of America 2011
Harry Y McSween Ralph L McNutt Thomas H Prettyman

Measurements by instruments on spacecraft have significantly advanced cosmochemistry. Spacecraft missions impose serious limitations on instrument volume, mass, and power, so adaptation of laboratory instruments drives technology. We describe three examples of flight instruments that collected cosmochemical data. Element analyses by Alpha Particle X-ray Spectrometers on the Mars Exploration Rov...

2005
A. Y. Potekhin

We study the relation between the mean effective surface temperature T s and the internal temperature Tb for magnetic neutron stars, assuming that the magnetic field near the surface has a presumably small-scale structure. The heavy-element (iron) and light-element (accreted) heat-blanketing envelopes are considered, and the results are compared with the case of a dipole magnetic field. We argu...

2000
Patrik Andersson Gottfried Otting

a Experiments with X-half-filter elements allow the separation of the resonances from protons bound and unbound to a spin X into different subspectra. This Communication presents a modified half-filter element where the filter delay is simultaneously used for chemical shift labeling and scalar coupling evolution in a semiconstant time experiment. The filter element is demonstrated with a H NOES...

2012
Kaveh PourAkbar Saffar Nima JamilPour Ahmad Raeisi Najafi Gholamreza Rouhi Ahmad Reza Arshi Abdolhossein Fereidoon

The presence of chemical bonding between functionalized carbon nanotubes and matrix in carbon nanotube reinforced composites is modeled by elastic beam elements representing covalent bonding characteristics. Neglecting other reinforcing mechanisms in the composite such as relatively weak interatomic Van der Waals forces, this model shows close results to the Rule of Mixtures model’s prediction ...

Journal: :Fresenius' journal of analytical chemistry 2000
A Lopez-Molinero A Castro J Pino J Perez-Arantegui J R Castillo

Artificial neural networks with unsupervised learning strategy known as Self-Organizing Maps were applied to classify ancient Roman glazed ceramics. Their clay ceramic bodies were analyzed by Inductively Coupled Plasma-Atomic Emission Spectroscopy and the chemical composition obtained was processed by this neural algorithm. The results obtained provide two types of information: firstly, classif...

Journal: :Angewandte Chemie 2006
Matthias Schädel

The number of chemical elements has increased considerably in the last few decades. Most excitingly, these heaviest, man-made elements at the far-end of the Periodic Table are located in the area of the long-awaited superheavy elements. While physical techniques currently play a leading role in these discoveries, the chemistry of superheavy elements is now beginning to be developed. Advanced an...

پایان نامه :وزارت علوم، تحقیقات و فناوری - دانشگاه تربیت مدرس - دانشکده فنی مهندسی 1388

طراحی دیوارهای حائل انعطاف پذیر به صورت مرسوم با استفاده از تحلیل های ساده شده و کلاسیک یا روشهای تجربی انجام می شود. متاسفانه کاربرد این روشها می تواند به تخمین های متفاوتی از پارامترهای عمده طراحی منجر گردد. هنگامی که تغییرمکانهای خاک مهم باشد و یا فضای ساخت محدود باشد، دیوارهای طره¬ای مدفون (با ویا بدون مهار) ممکن است استفاده شوند. انعطاف پذیری دیوارهای مدفون درمحدوده وسیعی تغییرمی کند و این...

Journal: :Proceedings of the National Academy of Sciences of the United States of America 2005
Philip A Bland Olivier Alard Gretchen K Benedix Anton T Kearsley Olwyn N Menzies Lauren E Watt Nick W Rogers

Bulk chondritic meteorites and terrestrial planets show a monotonic depletion in moderately volatile and volatile elements relative to the Sun's photosphere and CI carbonaceous chondrites. Although volatile depletion was the most fundamental chemical process affecting the inner solar nebula, debate continues as to its cause. Carbonaceous chondrites are the most primitive rocks available to us, ...

2004
Rhea K. Workman Stanley R. Hart

We derive an estimate for the chemical composition of the depleted MORB mantle (DMM), the source reservoir to mid-ocean ridge basalts (MORBs), which represents at least 30% the mass of the whole silicate Earth. A database for the chemical and physical properties of abyssal peridotites has become robust and complete enough to truly access a reference DMM. Using trace element depletion trends fro...

2012

Modeling transfer phenomena in several chemical engineering operations leads to the resolution of partial differential equations systems. According to the complexity of the operations mechanisms, the equations present a nonlinear form and analytical solution became difficult, we have then to use numerical methods which are based on approximations in order to transform a differential system to a...

نمودار تعداد نتایج جستجو در هر سال

با کلیک روی نمودار نتایج را به سال انتشار فیلتر کنید