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41.
IwrRODUcrlONStainlessstalhasbeenusedwidelyasbuildingrnateria1,especiallyasdecoratingrnate-rialinbuildings.Ordinarystainlesssteehasonlyonemonot0noussilverywhitCcolourwhichsomeimesdoesnotrnatchwithitSsurmundingenvironment.lnordert0improveitSdereratingperfonnaneeandexpanditsuse,muchresearchhasbeenconductedsincethe4O'st0trytoformabright,uniform,highcorrosi0nandwearresistantco1ourfilmonastainlesssteesurface.Duringtheeariystage,anirnmersionedhodwasused,i.e.inimrs-ingthestainlesssteelinahots0luti…  相似文献   
42.
高速滑坡问题是当前工程地质和环境地质学界极为关注的问题。本文对诸如滑体高速滑动所对应的时空界限、滑体滑动过程所产生的热效应以及空气浮托力等高速滑坡产生机制问题进行了初步探讨。  相似文献   
43.
A wide-field time-series CCD photometric survey of variable stars in the field of the open cluster NGC 2168 was carried out using the BATC Schmidt telescope. In total 13 new variable stars are discovered with three W UMa systems, one EA type and two EB type eclipsing binaries (one of them could be a W UMa system), and seven pulsating stars including three candidates of δScuti stars.  相似文献   
44.
粤东海岸东起闽粤交界的大埕湾,西迄深圳市的大鹏湾,岸线曲折,港湾较多,河溪人海泥沙在潮间带及紧邻5m 等深线以内形成大片海涂,土壤类型多样,以泥质和沙泥质土壤为主;除河口湾的土壤含盐量低外,其余较高;土壤有机质含量中等,钾素较丰富,磷素较低。因地处亚热带南缘,光、热和水资源条件较好,且多数海湾有深入内地的小海湾和潮沟,甚适合发展海水养殖与晒盐,韩江口的义丰河和海门龟头海大闸外等滩地尚有围垦价值。多处海湾潮滩沙土适合作海滨浴场,也有小片滩地红树林适合旅游观赏。  相似文献   
45.
Histological study on the ontogeny of the lymphoid organs, kidney, thymus and spleen of Japanese flounder, Paralichthys olivaceus, from hatching to 40 d was carried out. The pronephric kidney duct appeared early in hatching although the primordial haemopoietic stem cells were observed within a week after hatching. The spleen was first seen after 8d of hatching. The thymus appeared after 15d, situated near the pronephric kidney. Small lymphoid cells appeared during the later phase of the post-larval stage in the sequence of thymus, kidney and spleen. During the 40d of observations, there were no distinct inner or outer zones in thymus and no red or white pulp in spleen. These results suggest that the nonspecific defense immune system plays a very important role in the early larval stage of Japanese flounder.  相似文献   
46.
章申  孙景信 《地理研究》1990,9(2):58-66
本文论述了珠穆朗玛峯地区土壤中稀土元素的含量,以及它们在土壤中的分布模式,并发现土壤中稀土元素的含量水平在很大程度上受土壤母质的制约。  相似文献   
47.
48.
Starfish oocytes with intact germinal vesicles (GVs) were cut along desired planes with glass needles or ligated using silk thread loops into two parts and allowed to mature in vitro, and inseminated. The experimental results showed that (1) only the parts with GVs or partial GV contents (PGVCs) cleaved, those without any GV materials did not; but nucleated and non-nucleated fragments cut from mature eggs were able to divide; (2) the development of animal parts of oocytes containing GVs or PGVCs was like that of animal fragments of matured oocytes with female pronuclei; most of them gave rise to permanent blastulae, and just a few formed ectodermal vesicles with a little primary mesenchyme; (3) a large part of vegetal fragments with GVs or PGVCs, and the vegetal parts of mature eggs without female pronuclei developed into small but normal embryos; (4) the fragments containing GVs or PGVCs obtained from the oocytes along a plane parallel to the animal-vegetal (A-V) axis developed as normally as the halves (with or without female pronuclei) severed from mature eggs along the same axis. Based on the data above, it was concluded that (1) the non-chromatin materials in the oocyte GVs are indispensable for successful fertilization and cleavage of starfish eggs; (2) some factor (s) located asymmetrically in the vegetal hemispheres of starfish oocytes is (are) responsible for formation of the archenteron and primary mesenchyme. It is evident from the above findings that the oocyte cytoplasm of the starfish had already regionalized before the GV break-down. Contribution No. 1722 from the Institute of Oceanology, Academia Sinica  相似文献   
49.
Recent Doppler velocity measurements have revealed the existence of two planets orbiting the star HD 12661 on medium-eccentricity orbits. The inner planet has a period of 263.6 d and a mass of 2.3 Jupiter masses, and the outer planet has a period of 1444.5d and a mass of 1.57 Jupiter masses. The stability of this system requires the two planets to be in a state of mean-motion orbit resonances. By numerical method we have studied the orbit migration and stability of the system in its early ages under the action of the proto-stellar disk, and calculated the probabilities of the planets being captured into the mean -motion resonances during their migrations. It is found that at present the two planets are probably situated at the edge of the 11:2 mean-motion resonance and are in chaotic motions. This result may be helpful to clarify the arguments on the present configuration. Besides, it is indicated that very probably, after the formation of the system, the gaseous disk has almost disappeared before the planets migrated to the present configuration.  相似文献   
50.
1 Introduction The Qinghai-Tibet Plateau, known as the highest plateau with the most complex topography in the world, covers an area of more than 200km2, with a mean elevation of more than 4000m a.s.l. (Ye and Gao, 1979). Surrounded by the Earth’s highest mountains, such as the Himalayas, Pamir, Kunlun Mountains, the plateau plays a significant role in climate change in China even in the world, thus attracted great attention of researchers. Up to now, many achievements have been gained by…  相似文献   
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