FINE STRUCTURE AND COMPOSITION OF A SILICEOUS SPONGE SPICULE

Carbon replicas of siliceous sponge spicules.

Sponge Structure; Introduction and Applications

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the underlying structure of language proficiency and the proficiency level

هدف از انجام این تخقیق بررسی رابطه احتمالی بین سطح مهارت زبان خارجی (foreign language proficiency) و ساختار مهارت زبان خارجی بود. تعداد 314 زبان آموز مونث و مذکر که عمدتا دانشجویان رشته های زبان انگلیسی در سطوح کارشناسی و کارشناسی ارشد بودند در این تحقیق شرکت کردند. از لحاظ سطح مهارت زبان خارجی شرکت کنندگان بسیار با هم متفاوت بودند، (75 نفر سطح پیشرفته، 113 نفر سطح متوسط، 126 سطح مقدماتی). کلا ...

On the Fine Structure and Composition of the Nuclear Envelope

Nuclei from nearly ripe eggs of Rana pipiens were isolated and cleaned in 0.1 M KCl. The whole nucleus was then digested to various degrees with ribonuclease or trypsin, followed by washing and fixation in either osmium tetroxide or potassium permanganate. The nuclear envelope was dissected off, placed on a grid, air dried, and compared with undigested controls in the electron microscope. Some ...

A Solid State NMR Investigation of Recent Marine Siliceous Sponge Spicules

The composition of four recent siliceous marine sponge spicules was studied and compared. In particular, multinuclear (29Si, 13C, 31P) solid state nuclear magnetic resonance (NMR) allowed the characterization of both the mineral and organic constituents in a non-destructive manner. The silica network condensation was similar for all samples. The organic matter showed a similar pattern but varie...