全文获取类型
收费全文 | 846篇 |
免费 | 1篇 |
国内免费 | 12篇 |
专业分类
电工技术 | 1篇 |
综合类 | 2篇 |
化学工业 | 9篇 |
金属工艺 | 31篇 |
机械仪表 | 11篇 |
建筑科学 | 7篇 |
矿业工程 | 2篇 |
能源动力 | 5篇 |
轻工业 | 35篇 |
水利工程 | 4篇 |
石油天然气 | 2篇 |
无线电 | 22篇 |
一般工业技术 | 23篇 |
冶金工业 | 680篇 |
原子能技术 | 3篇 |
自动化技术 | 22篇 |
出版年
2023年 | 3篇 |
2022年 | 3篇 |
2021年 | 1篇 |
2020年 | 4篇 |
2019年 | 3篇 |
2018年 | 3篇 |
2017年 | 2篇 |
2016年 | 3篇 |
2015年 | 4篇 |
2014年 | 7篇 |
2013年 | 16篇 |
2012年 | 8篇 |
2011年 | 18篇 |
2010年 | 12篇 |
2009年 | 10篇 |
2008年 | 8篇 |
2007年 | 7篇 |
2006年 | 9篇 |
2005年 | 9篇 |
2004年 | 9篇 |
2003年 | 5篇 |
2002年 | 2篇 |
2001年 | 1篇 |
2000年 | 5篇 |
1999年 | 22篇 |
1998年 | 195篇 |
1997年 | 120篇 |
1996年 | 73篇 |
1995年 | 41篇 |
1994年 | 34篇 |
1993年 | 38篇 |
1992年 | 7篇 |
1991年 | 7篇 |
1990年 | 13篇 |
1989年 | 22篇 |
1988年 | 14篇 |
1987年 | 13篇 |
1986年 | 7篇 |
1985年 | 8篇 |
1984年 | 1篇 |
1983年 | 3篇 |
1982年 | 5篇 |
1981年 | 6篇 |
1980年 | 3篇 |
1978年 | 2篇 |
1977年 | 28篇 |
1976年 | 41篇 |
1975年 | 1篇 |
1955年 | 3篇 |
排序方式: 共有859条查询结果,搜索用时 472 毫秒
61.
In order to investigate the effect of aluminization on the oxidation properties of 12Cr martensitic heat resisting steel,
a specimen was prepared by forging after centrifugal casting. After aluminizing treatment under various conditions, scanning
electron microscopy observation, and hardness, line profile and x-ray diffraction analysis of the alloy layer were performed.
The results confirmed that the thickness of the layer of Al13Fe4, with a Vickers hardness of over 880, increased with increasing aluminizing temperature and time. Moreover, it was concluded
from the results of the oxidation experiment that the oxidation properties of the aluminized specimen were improved by up
to approximately 30 %. 相似文献
62.
63.
64.
65.
CG Jones RS Ostfeld MP Richard EM Schauber JO Wolff 《Canadian Metallurgical Quarterly》1998,279(5353):1023-1026
In eastern U.S. oak forests, defoliation by gypsy moths and the risk of Lyme disease are determined by interactions among acorns, white-footed mice, moths, deer, and ticks. Experimental removal of mice, which eat moth pupae, demonstrated that moth outbreaks are caused by reductions in mouse density that occur when there are no acorns. Experimental acorn addition increased mouse density. Acorn addition also increased densities of black-legged ticks, evidently by attracting deer, which are key tick hosts. Mice are primarily responsible for infecting ticks with the Lyme disease agent. The results have important implications for predicting and managing forest health and human health. 相似文献
66.
EC Griffith Z Su S Niwayama CA Ramsay YH Chang JO Liu 《Canadian Metallurgical Quarterly》1998,95(26):15183-15188
Angiogenesis inhibitors are a novel class of promising therapeutic agents for treating cancer and other human diseases. Fumagillin and ovalicin compose a class of structurally related natural products that potently inhibit angiogenesis by blocking endothelial cell proliferation. A synthetic analog of fumagillin, TNP-470, is currently undergoing clinical trials for treatment of a variety of cancers. A common target for fumagillin and ovalicin recently was identified as the type 2 methionine aminopeptidase (MetAP2). These natural products bind MetAP2 covalently, inhibiting its enzymatic activity. The specificity of this binding is underscored by the lack of inhibition of the closely related type 1 enzyme, MetAP1. The molecular basis of the high affinity and specificity of these inhibitors for MetAP2 has remained undiscovered. To determine the structural elements of these inhibitors and MetAP2 that are involved in this interaction, we synthesized fumagillin analogs in which each of the potentially reactive epoxide groups was removed either individually or in combination. We found that the ring epoxide in fumagillin is involved in the covalent modification of MetAP2, whereas the side chain epoxide group is dispensable. By using a fumagillin analog tagged with fluorescein, His-231 in MetAP2 was identified as the residue that is covalently modified by fumagillin. Site-directed mutagenesis of His-231 demonstrated its importance for the catalytic activity of MetAP2 and confirmed that the same residue is covalently modified by fumagillin. These results, in agreement with a recent structural study, suggest that fumagillin and ovalicin inhibit MetAP2 by irreversible blockage of the active site. 相似文献
67.
JO Nielsen 《Canadian Metallurgical Quarterly》1998,113(9):287-289
The most important preventive measures against accidental HIV infection in health care are the education of personnel and the observance of routine procedures in everyday work. In this way, the accidental infection rate can be reduced by more than 50 per cent. Consistent registration of the causes of accidental infection can further reduce work-related risks. In January, the Danish authorities issued guidelines for the use of antiviral chemoprophylaxis against HIV infection following occupational exposure. A four-week course of triple-drug anti-retroviral prophylaxis is recommended to prevent HIV infection in causes of needle-stick or other penetration injuries. 相似文献
68.
M Robert JO Roux F Bourelly AM Boularan J Guiter L Monnier 《Canadian Metallurgical Quarterly》1994,74(3):294-297
OBJECTIVE: To evaluate the circadian fluctuations in the risk of urinary calcium oxalate stone formation with regard to critical periods of crystallization. PATIENTS AND METHODS: Over a given time period, the Tiselius index depends on urine volume and urinary excretion of oxalate, calcium, citrate and magnesium. This crystallization potential was evaluated during three successive periods spread over 24 h for 25 recurrent stone-formers aged 16-76 years (mean 50) and 25 control subjects aged 27-71 years (mean 44). RESULTS: There was no significant difference in the value of the Tiselius index for all equivalent time periods in both groups of patients. The minimum value was recorded in the afternoon and the circadian pattern of the index illustrated the predominant importance of urinary output in its determination. Morning urinary concentrations and excretions of citrate, and nocturnal levels of magnesium were significantly higher in the stone-formers when compared with the control subjects. CONCLUSION: The lithogenic risk for calcium oxalate stones was maximal at the end of the night or during the early morning, when urinary output was minimal. This circadian study revealed abnormalities that are not apparent from non-fractionated 24 h urine samples, and which were potentially relevant to therapy. 相似文献
69.
Z Mourelatos JO Gonatas LM Nycum NK Gonatas JA Biegel 《Canadian Metallurgical Quarterly》1995,28(2):354-355
70.