全文获取类型
收费全文 | 1616篇 |
免费 | 4篇 |
专业分类
化学工业 | 12篇 |
金属工艺 | 1篇 |
机械仪表 | 2篇 |
建筑科学 | 4篇 |
轻工业 | 5篇 |
水利工程 | 1篇 |
一般工业技术 | 4篇 |
冶金工业 | 1589篇 |
自动化技术 | 2篇 |
出版年
2023年 | 1篇 |
2022年 | 4篇 |
2021年 | 1篇 |
2018年 | 3篇 |
2017年 | 1篇 |
2016年 | 2篇 |
2014年 | 2篇 |
2011年 | 3篇 |
2008年 | 2篇 |
2006年 | 2篇 |
2004年 | 2篇 |
2003年 | 6篇 |
1999年 | 41篇 |
1998年 | 464篇 |
1997年 | 273篇 |
1996年 | 190篇 |
1995年 | 109篇 |
1994年 | 79篇 |
1993年 | 87篇 |
1992年 | 13篇 |
1991年 | 14篇 |
1990年 | 17篇 |
1989年 | 29篇 |
1988年 | 21篇 |
1987年 | 17篇 |
1986年 | 14篇 |
1985年 | 15篇 |
1982年 | 6篇 |
1981年 | 17篇 |
1980年 | 22篇 |
1979年 | 2篇 |
1978年 | 7篇 |
1977年 | 45篇 |
1976年 | 104篇 |
1975年 | 3篇 |
1955年 | 2篇 |
排序方式: 共有1620条查询结果,搜索用时 31 毫秒
1.
C Harro GL Braden AB Morris GS Lipkowitz RL Madden 《Canadian Metallurgical Quarterly》1997,24(5):955-957
Nontuberculous mycobacteria are increasingly recognized as important pathogens in peritonitis associated with continuous ambulatory peritoneal dialysis (CAPD). Mycobacterium gordonae rarely causes human infection and is the least likely mycobacterium to produce clinical infection in CAPD patients. We describe a patient with persistent M. gordonae peritonitis acquired while undergoing CAPD. During 18 months of treatment, clinical improvement occurred but a microbiological cure could not be achieved. Principles of therapy for mycobacterial peritonitis developing during CAPD are reviewed, and potential explanations for our patient's failure to respond to therapy are discussed. 相似文献
2.
3.
4.
AB Deisseroth Z Zu D Claxton EG Hanania S Fu D Ellerson L Goldberg M Thomas K Janicek WF Anderson 《Canadian Metallurgical Quarterly》1994,83(10):3068-3076
Relapse after autologous bone marrow transplantation for chronic myelogenous leukemia (CML) can be due either to the persistence of leukemia cells in systemic tissues following preparative therapy, or due to the persistence of leukemia cells in the autologous marrow used to restore marrow function after intensive therapy. To help distinguish between these two possible causes of relapse, we used safety-modified retroviruses, which contain the bacterial resistance gene NEO, to mark autologous marrow cells that had been collected from patients early in the phase of hematopoietic recovery after in vivo chemotherapy. The cells were then subjected to ex vivo CD34 selection following collection and 30% of the bone marrow were exposed to a safety-modified virus. This marrow was infused after delivery of systemic therapy, which consisted of total body irradiation (1,020 cGy), cyclophosphamide (120 mg/kg), and VP-16 (750 mg/m2). RT PCR assays specific for the bacterial NEO mRNA, which was coded for by the virus, and the bcr-abl mRNA showed that in two evaluable CML patients transplanted with marked cells, sufficient numbers of leukemia cells remained in the infused marrow to contribute to systemic relapse. In addition, both normal and leukemic cells positive for the retroviral transgenome persisted in the systemic circulation of the patients for at least 280 days posttransplant showing that the infused marrow was responsible for the return of hematopoiesis following the preparative therapy. This observation shows that it is possible to use a replication-incompetent safety-modified retrovirus in order to introduce DNA sequences into the hematopoietic cells of patients undergoing autologous bone marrow transplantation. Moreover, this data suggested that additional fractionation procedures will be necessary to reduce the probability of relapse after bone marrow transplantation in at least the advanced stages of the disease in CML patients undergoing autologous bone marrow transplantation procedures. 相似文献
5.
6.
7.
M Manickam M Ramanathan MA Jahromi JP Chansouria AB Ray 《Canadian Metallurgical Quarterly》1997,60(6):609-610
Glucose levels in rats with hyperglycemia induced by streptozotocin were determined after i.p. administration of marsupsin (1), pterosupin (2), and pterostilbene (3), three important phenolic constituents of the heartwood of Pterocarpus marsupium. Marsupsin and pterostilbene significantly lowered the blood glucose level of hyperglycemic rats, and the effect was comparable to that of 1,1-dimethylbiguanide (metformin). 相似文献
8.
Y Numagami AB Zubrow OP Mishra M Delivoria-Papadopoulos 《Canadian Metallurgical Quarterly》1997,69(4):1542-1547
Nitric oxide (NO) is reported to cause neuronal damage through various mechanisms. The present study tests the hypothesis that NO synthase inhibition by N(omega)-nitro-L-arginine (NNLA) will result in decreased oxygen-derived free radical production leading to the preservation of cell membrane structure and function during cerebral hypoxia. Ten newborn piglets were pretreated with NNLA (40 mg/kg); five were subjected to hypoxia, whereas the other five were maintained with normoxia. An additional 10 piglets without NNLA treatment underwent the same conditions. Hypoxia was induced with a lowered FiO2 and documented biochemically by decreased cerebral ATP and phosphocreatine levels. Free radicals were detected by using electron spin resonance spectroscopy with a spin trapping technique. Results demonstrated that free radicals, corresponding to alkoxyl radicals, were induced by hypoxia but were inhibited by pretreatment with NNLA before inducing hypoxia. NNLA also inhibited hypoxia-induced generation of conjugated dienes, products of lipid peroxidation. Na+,K+-ATPase activity, an index of cellular membrane function, decreased following hypoxia but was preserved by pretreatment with NNLA. These data demonstrate that during hypoxia NO generates free radicals via peroxynitrite production, presumably causing lipid peroxidation and membrane dysfunction. These results suggest that NO is a potentially limiting factor in the peroxynitrite-mediated lipid peroxidation resulting in membrane injury. 相似文献
9.
10.
PURPOSE: Conventional techniques for implant metal framework fabrication produce error of a magnitude that is inconsistent with the passive-fit requirement for osseointegrated implants. To understand the correlation between prosthesis fit and the implant-tissue response, evaluation of the interface tissue reactions to customary levels of fit is required. The purpose of this study is to determine the accuracy of torch casting full arch frameworks using a high palladium alloy and a ringless phosphate-bonded investment technique. MATERIALS AND METHODS: Three different variables were considered relative to casting accuracy effect. The first variable, completeness of mold-fill, compared cast specimens where the entire sprue system was filled as part of the casting and cast specimens without the sprue system filled. The second variable, phosphate-bonded investment special liquid concentrations, compared groups of castings produced from 0%, 12%, 25%, and 50% special liquid. The third variable, investment mold shape, compared casting produced from a conventional ringless mold shape with a modified ringless mold shape where the investment in the same horizontal plane as the pattern was equal in thickness at the internal and external surfaces. Horizontal and vertical distances on the wax pattern and resulting framework were measured using a machinists microscope to determine casting error. Combined vertical and horizontal error was used for comparison between groups (one-way analysis of variance). RESULTS: No significant differences existed among the three groups compared (P > 0.05). The mean error comparison between the complete and incomplete mold-fill groups showed no statistical difference, while the incomplete fill group was found to be more porous. The mean error of all groups (0.130 mm) exceeded the recommended level of fit needed to satisfy the passive fit requirement by more than 10-fold. CONCLUSIONS: These results verify clinical observation and suggest that the use of conventional lost wax casting technique to cast one-piece full arch implant frameworks is both imprecise and inaccurate as judged against the passive fit requirement. The consequences of screw-fastening misfitting prostheses to osseointegrated implants is currently under investigation. 相似文献