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排序方式: 共有246条查询结果,搜索用时 15 毫秒
181.
182.
Enomoto R Tanimori T Naito T Yoshida T Yanagita S Mori M Edwards PG Asahara A Bicknell GV Gunji S Hara S Hara T Hayashi S Itoh C Kabuki S Kajino F Katagiri H Kataoka J Kawachi A Kifune T Kubo H Kushida J Maeda S Maeshiro A Matsubara Y Mizumoto Y Moriya M Muraishi H Muraki Y Nakase T Nishijima K Ohishi M Okumura K Patterson JR Sakurazawa K Suzuki R Swaby DL Takano K Takano T Tokanai F Tsuchiya K Tsunoo H Uruma K Watanabe A Yoshikoshi T 《Nature》2002,416(6883):823-826
Protons with energies up to approximately 10(15) eV are the main component of cosmic rays, but evidence for the specific locations where they could have been accelerated to these energies has been lacking. Electrons are known to be accelerated to cosmic-ray energies in supernova remnants, and the shock waves associated with such remnants, when they hit the surrounding interstellar medium, could also provide the energy to accelerate protons. The signature of such a process would be the decay of pions (pi(0)), which are generated when the protons collide with atoms and molecules in an interstellar cloud: pion decay results in gamma-rays with a particular spectral-energy distribution. Here we report the observation of cascade showers of optical photons resulting from gamma-rays at energies of approximately 10(12) eV hitting Earth's upper atmosphere, in the direction of the supernova remnant RX J1713.7-3946. The spectrum is a good match to that predicted by pion decay, and cannot be explained by other mechanisms. 相似文献
183.
184.
Watanabe H Nakashima K Saito H Slaytor M 《Cellular and molecular life sciences : CMLS》2002,59(11):1983-1992
An endo-β-1,4-glucanase (EG) was purified from the hindgut of an Australian mound-building termite, Coptotermes lacteus. The hindgut extract had a peak separate from those for extracts obtained from the salivary glands and the midgut based on
sephacryl S-200 gel chromatography, and also demonstrated an origin different from the endogenous EGs of the termite itself.
The recovery was further purified by SDS-PAGE, and its N-terminal amino acid sequence analyzed. This showed high homology
to EGs from glycoside hydrolase family (GHF) 7. PCR-based cloning methods were applied to the hindgut contents of C. lacteus and individual protozoan symbionts from C. formosanus. cDNAs encoding putative EGs homologous to GHF7 members were then identified. The functionality of one of the putative proteins
was confirmed by its expression in Escherichia coli.
Received 18 September 2002; accepted 20 September 2002
RID="*"
ID="*"Corresponding author. 相似文献
185.
Mutations in IRF6 cause Van der Woude and popliteal pterygium syndromes 总被引:25,自引:0,他引:25
Kondo S Schutte BC Richardson RJ Bjork BC Knight AS Watanabe Y Howard E de Lima RL Daack-Hirsch S Sander A McDonald-McGinn DM Zackai EH Lammer EJ Aylsworth AS Ardinger HH Lidral AC Pober BR Moreno L Arcos-Burgos M Valencia C Houdayer C Bahuau M Moretti-Ferreira D Richieri-Costa A Dixon MJ Murray JC 《Nature genetics》2002,32(2):285-289
186.
H. Watanabe 《Cellular and molecular life sciences : CMLS》1970,26(1):69-70
Zusammenfassung Mittels elektronenmikroskopischer Untersuchungen wird die Anwesenheit adrenergischer Nervenendigungen im Ganglion hypogastricum des Meerschweinchens bewiesen. 相似文献
187.
Gastric acid secretory responses of acute gastric fistula preparation in anesthetized young chickens
Summary A reliable technique which permits quantitative determination of the gastric acid secretory responses to drugs was developed in anesthetized young chickens.The present study was supported by a Grant from the Ministry of Education of Japan. We are indebted to Mr.M. Murakami, Mr.S. Kojima and MissU. Kariya, for their technical assistance. 相似文献
188.
ACTH response induced by interleukin-1 is mediated by CRF secretion stimulated by hypothalamic PGE 总被引:3,自引:0,他引:3
We investigated whether hypothalamic prostaglandin E2 (PGE2) and corticotropin releasing factor (CRF) are responsible for the development of the adrenocorticotropic hormone (ACTH) response induced by interleukin-1 alpha (IL-1 alpha). The present results show that ACTH responses induced by intravenous injection of IL-1 alpha were suppressed by systemic pretreatment with indomethacin and that intrahypothalamic injection of PGE2 stimulates the secretion of ACTH. Furthermore, systemic pretreatment with anti-CRF antibody significantly suppressed the ACTH response induced by intrahypothalamic injection of PGE2. These data suggest that the ACTH response induced by IL-1 is mediated by CRF secretion stimulated by hypothalamic PGE2. 相似文献
189.
Hassall's corpuscles instruct dendritic cells to induce CD4+CD25+ regulatory T cells in human thymus 总被引:1,自引:0,他引:1
Hassall's corpuscles-first described in the human thymus over 150 years ago-are groups of epithelial cells within the thymic medulla. The physical nature of these structures differs between mammalian species. Although Hassall's corpuscles have been proposed to act in both the removal of apoptotic thymocytes and the maturation of developing thymocytes within the thymus, the function of Hassall's corpuscles has remained an enigma. Here we report that human Hassall's corpuscles express thymic stromal lymphopoietin (TSLP). Human TSLP activates thymic CD11c-positive dendritic cells to express high levels of CD80 and CD86. These TSLP-conditioned dendritic cells are then able to induce the proliferation and differentiation of CD4(+)CD8(-)CD25(-) thymic T cells into CD4(+)CD25(+)FOXP3(+) (forkhead box P3) regulatory T cells. This induction depends on peptide-major histocompatibility complex class II interactions, and the presence of CD80 and CD86, as well as interleukin 2. Immunohistochemistry studies reveal that CD25(+)CTLA4(+) (cytotoxic T-lymphocyte-associated protein 4) regulatory T cells associate in the thymic medulla with activated or mature dendritic cells and TSLP-expressing Hassall's corpuscles. These findings suggest that Hassall's corpuscles have a critical role in dendritic-cell-mediated secondary positive selection of medium-to-high affinity self-reactive T cells, leading to the generation of CD4(+)CD25(+) regulatory T cells within the thymus. 相似文献
190.
Summary The increased production of 1 in injured liver is primarily associated with hepatic injury and not with liver cell regeneration. 相似文献