全文获取类型
收费全文 | 1156篇 |
免费 | 1篇 |
专业分类
电工技术 | 1篇 |
化学工业 | 12篇 |
机械仪表 | 2篇 |
建筑科学 | 8篇 |
矿业工程 | 3篇 |
能源动力 | 5篇 |
轻工业 | 5篇 |
石油天然气 | 1篇 |
无线电 | 18篇 |
一般工业技术 | 20篇 |
冶金工业 | 1071篇 |
原子能技术 | 1篇 |
自动化技术 | 10篇 |
出版年
2019年 | 2篇 |
2017年 | 3篇 |
2014年 | 1篇 |
2013年 | 15篇 |
2012年 | 1篇 |
2011年 | 2篇 |
2010年 | 3篇 |
2009年 | 2篇 |
2008年 | 5篇 |
2007年 | 2篇 |
2006年 | 5篇 |
2005年 | 3篇 |
2003年 | 3篇 |
2001年 | 4篇 |
2000年 | 2篇 |
1999年 | 31篇 |
1998年 | 349篇 |
1997年 | 187篇 |
1996年 | 128篇 |
1995年 | 60篇 |
1994年 | 54篇 |
1993年 | 64篇 |
1992年 | 9篇 |
1991年 | 6篇 |
1990年 | 12篇 |
1989年 | 11篇 |
1988年 | 18篇 |
1987年 | 9篇 |
1986年 | 9篇 |
1985年 | 10篇 |
1984年 | 2篇 |
1983年 | 3篇 |
1982年 | 7篇 |
1981年 | 3篇 |
1980年 | 12篇 |
1979年 | 2篇 |
1978年 | 4篇 |
1977年 | 25篇 |
1976年 | 76篇 |
1975年 | 1篇 |
1973年 | 2篇 |
1972年 | 2篇 |
1971年 | 2篇 |
1969年 | 2篇 |
1961年 | 1篇 |
1956年 | 1篇 |
1955年 | 2篇 |
排序方式: 共有1157条查询结果,搜索用时 15 毫秒
71.
72.
73.
Results are presented from a monitoring study of the performance of a sample of UK domestic PV systems. Five-minute average climatic and performance data was recorded for 27 PV systems at two sites for up to 2 years of operation. On average, the annual energy losses due to faults were 3.6% (Site A, first year of operation), 6.6% (Site A, second year of operation) and 18.9% (Site B, first year of operation). Simple empirical models are constructed to describe the performance of the PV systems under ‘normal operation’ (when no faults occur). New analysis techniques are developed which estimate the energy losses of four different fault categories: sustained zero efficiency faults; brief zero efficiency faults; shading; and non-zero efficiency non-shading faults. The results demonstrate that faults have the potential to cause significant energy losses in domestic PV systems. The benefits of applying the data analysis techniques described in this work to PV system clusters and other urban micro-generation technologies are discussed. 相似文献
74.
75.
Methotrexate pharmacokinetic studies, performed on a patient with renal impairment who had toxic effects following 20 mg/sq m of intrathecally administered methotrexate, demonstrated prolonged serum concentrations of the drug, which accounted for the condition. After the return of normal renal function, pharmacokinetic studies were repeated following the same dose and route of administration of methotrexate. On this occasion there was a rapid clearance of serum methotrexate below toxic levels. 相似文献
76.
77.
A. R. Firth N. B. Gray A. K. Kyllo G. K. Williams 《Metallurgical and Materials Transactions B》2001,32(1):173-179
A solidified layer on the inside of a cooled flow channel can be used to control the flow rate of molten material through
that channel. This concept can be used for flow rate control of molten furnace products in the metallurgical industry. In
this study, internal solidification of molten metal flows has been modeled mathematically for both steady-state and dynamic
cases. The model predicted solidified layer thickness and metal flow rate. Experimental verification of the mathematical model
was obtained using molten tin. Novel design features of the experimental apparatus included the use of boiling heat transfer
and the vertical mounting of the cooling section. Engineering knowledge regarding the design, operation, and control of a
pilot scale (24 kg/s) molten metal circuit was obtained during the construction, commissioning, and operation of the experimental
apparatus. Experimental results for tin flow rate from the experimental apparatus were within experimental error of the predictions
of the mathematical model. 相似文献
78.
79.
JR Passweg G Socié W Hinterberger A Bacigalupo JC Biggs BM Camitta RE Champlin RP Gale E Gluckman EC Gordon-Smith JM Hows JP Klein ML Nugent R Pasquini PA Rowlings B Speck A Tichelli MJ Zhang MM Horowitz MM Bortin 《Canadian Metallurgical Quarterly》1997,90(2):858-864
Bone marrow transplants for severe aplastic anemia were first performed in the 1970s. Transplant regimens, supportive care, and patient selection have changed substantially since then. Our objective was to determine the impact of these changes on transplant outcome. We studied 1,305 recipients of HLA-identical sibling transplants for aplastic anemia between 1976 and 1992, reported to the IBMTR by 179 centers. We compared survival of transplants performed in three intervals (1976 through 1980 [n = 186], 1981 through 1987 [n = 648], and 1988 through 1992 [n = 471]) using Cox proportional hazards regression. Five-year survival (+/-95% confidence interval) increased from 48% +/- 7% in the 1976-1980 cohort to 66% +/- 6% in the 1988-1992 cohort (P < .0001). Risks of graft-versus-host disease (GVHD) and interstitial pneumonia decreased over time, but the risk of graft failure did not. Higher long-term survival resulted primarily from decreased mortality in the first 3 months posttransplantation. Late mortality risks were low and changed little over the intervals studied. In multivariate analysis, changes in transplantation strategies accounted for most but not all of the improved outcome. Use of cyclosporine to prevent GVHD was the most important factor. Changes in patient selection did not seem to explain improved survival. Survival after HLA-identical sibling bone marrow transplantations for aplastic anemia has improved since 1976. Changes in GVHD prophylaxis account for much of this improvement. Other changes may also operate. 相似文献
80.
PG Janu KD Sellers EC Mangiante 《Canadian Metallurgical Quarterly》1997,63(12):1065-9; discussion 1069-71
Inguinal herniorrhaphy remains one of the most common surgical operations, with approximately 10 to 20 per cent performed for recurrence. Reviews by specialized hernia centers show mesh repair has a recurrence rate of 0.2 per cent. Detractors of this repair include increased cost, technical difficulty, and risk for infection. The purpose of this study was to compare mesh versus nonmesh inguinal herniorrhaphy at a large teaching institution. From 1985 to 1994, 892 patients underwent primary repair for inguinal hernia at the Veterans Administration Hospital at Memphis, TN. Patients were stratified by repair [Lichtenstein (Mesh), open anterior (Bassini, Marcy, McVay, and Shouldice), laparoscopic (Lap), and preperitoneal (Post)]. Operative time for Mesh repair (111 +/- 2 minutes) was longer than for Bassini or McVay (91 +/- 2 and 98 +/- 2 minutes; P < 0.05), and Lap repairs were longer than all others (192 +/- 16 minutes; P < 0.05). Hospital stay averaged 2.2 +/- 0.1 days for Mesh versus 2.6 +/- 0.1 days for all repairs combined (P = not significant). Mesh patients developed four wound infections (1.0%), none requiring mesh removal, versus nine infections (1.8%) in other groups (P = not significant). One Mesh patient (0.3%) developed recurrence, compared with 16 (3.5%) with open anterior repair (P < 0.01). Inguinal herniorrhaphy using an open mesh repair technique provides superior recurrence rates without increasing risk for infection, length of stay, or technical difficulty. 相似文献