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991.
Richard Watson     
The development of the circular dividing engine in England is traced from Henry Hindley and Jesse Ramsden through the improvements introduced by Ramsden's successors to the self-acting engine of William Simms. Particular emphasis is given to the invention, evolution and transmission of the methods used to achieve accuracy in: dividing the wheel; ratching the teeth and matching them to the endless screw; and mounting the cutter. The procedures adopted by Ramsden and Troughton for correcting initial dividing marks are also described.  相似文献   
992.
Normal 0 false false false EN-US X-NONE X-NONE MicrosoftInternetExplorer4 st1\:*{behavior:url(#ieooui) } /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;} Sixty-four cougar ( Felis concolor ) stomachs and 41 intestinal tracts were examined for food items in northeastern Oregon from 1976 through 1979. Food items, in order of decreasing frequency, were mule deer ( Odocoileus hemionus ), North American elk ( Cervus elaphus ), porcupine ( Erethizon dorsatum ), snowshoe hare ( Lepus americanus ), and deer mouse ( Peromyscus maniculatus ).    相似文献   
993.
994.
The occurrence of infectious disease represents a failure of the immune system, a failure that must be prevented by effective vaccination or remedied by treatment. Vaccination against acute diseases such as smallpox and polio are very effective, due to the rapid and increased immune response of vaccinated individuals upon natural infection. In contrast, effective vaccination against intracellular pathogens that cause chronic diseases, such as the leishmaniases, tuberculosis and AIDS, has not been achieved. Clinical observations suggest cell-mediated, Th1 responses, exclusive of antibody production and the generation of Th2 cells, are optimally protective against these intracellular pathogens. Effective vaccination must ensure the generation of such a protective response. We explore here whether understanding very broad features of the regulation of the immune response can accommodate modern findings on the immunological features of these diseases, and provide a perspective within which strategies for effective vaccination and treatment can be developed.  相似文献   
995.
996.
To investigate the role of autologous serum components in the recognition of damaged cells by macrophages, we examined the binding and phagocytosis of damage oxidatively damaged red blood cells with Cu2+ and ascorbate (oxRBCs) by autologous resident mouse peritoneal macrophages. The binding of oxRBCs by macrophages was independent of the presence of serum. However, phagocytosis by macrophages increased with serum concentration, and macrophages showed little ingestion of oxRBCs in a serum-free medium. Macrophages neither bound nor appreciably ingested native RBCs (before oxidation) in either the absence or presence of autologous serum. Mouse macrophages ingested significantly more native as well as oxRBCs in the presence of heat-inactivated fetal calf serum than in the presence of heat-inactivated mouse serum. Pretreated oxRBCs with normal serum were rarely ingested by macrophages in a serum-free medium. Phagocytosis of oxRBCs was significantly inhibited by depletion of IgG or calcium from serum, by heat inactivation of complement, or by antiserum against mouse C3. These results demonstrate that serum components such as IgG, C3, and calcium are involved in phagocytosis of oxRBCs by autologous macrophages.  相似文献   
997.
Normal 0 false false false EN-US X-NONE X-NONE MicrosoftInternetExplorer4 st1\:*{behavior:url(#ieooui) } /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;} The relative abundance and habitat affinities of breeding and migratory waterfowl were documented for a 16,556 ha (40,880 acre) area of the Navajo Indian Reservation, San Juan County, New Mexico. The objective of the 1973 – 1974 study was to obtain baseline data for use as part of an environmental assessment for coal gasification plants and an associated strip mine proposed for an area not previously described in ornithological journals. Roadside breeding - bird surveys resulted in the observation of 26 species of birds, of which the horned lark was most abundant. Additional breeding - bird observations were made during afternoon reconnaissance surveys around stock ponds and arroyos, and by a helicopter survey of cliff - nesting raptors. Nine of 30 raptor nests located were active. Migratory waterfowl surveys were made in September and November at four stock ponds and a marsh on the study area. Peak waterfowl numbers were present in September, when teal and shovelers were the most abundant species. The importance of stock ponds to breeding and migratory birds and the significance of cliffs to nesting raptors were discussed. Details of observations made for five species of birds designated ";threatened"; or ";status undetermined"; were presented.     相似文献   
998.
Design for six sigma (DFSS) is a powerful approach of designing products,processes,and services with the objective of meeting the needs of customers in a cost-effective manner.DFSS activities are class...  相似文献   
999.
Streambed surveys were conducted along the upper Colorado River, Colorado, to describe the distributions of Claassenia sabulosa larvae in relation to current speed and to determine their diets. We also addressed diel feeding periodicity by sampling during both day and night. Claassenia sabulosa was more abundant in riffle habitats than in runs. A positive relationship existed between C. sabulosa abundance and stream current, with larval size increasing with current speed. Chironomidae, Baetidae, and Simulidae collectively accounted for 93% of the prey found in stonefly guts; however, these categories were not consumed equally by all C. sabulosa . Smaller C. sabulosa primarily ate chironomids, and larger individuals consumed more baetids. Only a slight difference existed in the percentage of empty guts between night- and day-collected stoneflies, and ranges of prey per gut at night were higher than those in the day, suggesting that these stoneflies may forage more intensively at night.  相似文献   
1000.
公路基本建设事业的快速发展,对公路养护工程提出了更高的要求,公路养护不断遇到新的难题,面对困难和挑战。文章结合本地区公路养护实际工作实践,对公路养护管理存在的问题进行了分析,并探讨了相应对策。  相似文献   
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