全文获取类型
收费全文 | 1560篇 |
免费 | 48篇 |
国内免费 | 6篇 |
专业分类
电工技术 | 10篇 |
化学工业 | 140篇 |
金属工艺 | 22篇 |
机械仪表 | 54篇 |
建筑科学 | 37篇 |
矿业工程 | 7篇 |
能源动力 | 21篇 |
轻工业 | 71篇 |
水利工程 | 5篇 |
无线电 | 95篇 |
一般工业技术 | 179篇 |
冶金工业 | 870篇 |
原子能技术 | 2篇 |
自动化技术 | 101篇 |
出版年
2023年 | 6篇 |
2022年 | 12篇 |
2021年 | 30篇 |
2020年 | 13篇 |
2019年 | 12篇 |
2018年 | 16篇 |
2017年 | 22篇 |
2016年 | 22篇 |
2015年 | 23篇 |
2014年 | 36篇 |
2013年 | 48篇 |
2012年 | 54篇 |
2011年 | 72篇 |
2010年 | 43篇 |
2009年 | 53篇 |
2008年 | 28篇 |
2007年 | 39篇 |
2006年 | 27篇 |
2005年 | 20篇 |
2004年 | 25篇 |
2003年 | 27篇 |
2002年 | 13篇 |
2001年 | 14篇 |
2000年 | 9篇 |
1999年 | 38篇 |
1998年 | 254篇 |
1997年 | 170篇 |
1996年 | 127篇 |
1995年 | 67篇 |
1994年 | 47篇 |
1993年 | 45篇 |
1992年 | 9篇 |
1991年 | 20篇 |
1990年 | 18篇 |
1989年 | 24篇 |
1988年 | 10篇 |
1987年 | 6篇 |
1986年 | 9篇 |
1985年 | 7篇 |
1983年 | 2篇 |
1982年 | 3篇 |
1980年 | 10篇 |
1978年 | 2篇 |
1977年 | 20篇 |
1976年 | 52篇 |
1975年 | 1篇 |
1973年 | 2篇 |
1972年 | 1篇 |
1968年 | 1篇 |
1955年 | 1篇 |
排序方式: 共有1614条查询结果,搜索用时 15 毫秒
1.
Woo‐Seok Cheong 《ETRI Journal》2003,25(6):503-509
Selective epitaxial growth (SEG) of silicon has attracted considerable attention for its good electrical properties and advantages in building microstructures in high‐density devices. However, SEG problems, such as an unclear process window, selectivity loss, and nonuniformity have often made application difficult. In our study, we derived processing diagrams for SEG from thermodynamics on gas‐phase reactions so that we could predict the SEG process zone for low pressure chemical vapor deposition. In addition, with the help of both the concept of the effective supersaturation ratio and three kinds of E‐beam patterns, we evaluated and controlled selectivity loss and nonuniformity in SEG, which is affected by the loading effect. To optimize the SEG process, we propose two practical methods: One deals with cleaning the wafer, and the other involves inserting dummy active patterns into the wide insulator to prevent the silicon from nucleating. 相似文献
2.
Norton NBD 200 silicon nitride ceramics were implanted with sodium to a dose of 7.0×1015cm-2 at 72 keV (1 at% peak sodium content at 100 nm). The sodium-implanted samples were further implanted with aluminium to 7.3×1015cm-2 at 87 keV (1 at% peak aluminium content at 100 nm). The implanted and unimplanted samples were oxidized in 1 atm dry oxygen
at 1100 and 1300°C for 2–6 h. Profilometry and scanning electron microscopy measurements indicated that sodium implantation
led to up to a two-fold increase in the oxidation rate of silicon nitride. The sodium effect was effectively neutralized when
aluminium was co-implanted. The opposite effects of sodium and aluminium on the oxidation resistance of silicon nitride can
be attributed to their different roles in modifying the structure and properties of the oxide formed.
This revised version was published online in November 2006 with corrections to the Cover Date. 相似文献
3.
FC Breedveld 《Canadian Metallurgical Quarterly》1997,141(15):717-719
Slow-acting antirheumatic drugs (SAARDs) are usually prescribed in rheumatoid arthritis only when non-steroid anti-inflammatory drugs can no longer suppress the inflammation or when articular damage is radiologically apparent. It was established recently that articular damage occurs in an early phase of RA. This damage is linked to subsequent disability; to prevent it is the purpose of SAARDs. In view of the short-term reduction of arthritis activity and improvement of function as well as the meanwhile established fact that the side effects of SAARDs are not different from those of other antirheumatic agents, SAARDs should be prescribed in an early phase of RA. 相似文献
4.
5.
6.
7.
Rh/Lil/SnR4 is an effective catalyst system for the conversion of methyl formate to acetic acid under carbon monoxide pressure. The effects
of solvent and initial CO partial pressure on the turnover rate of the reaction were investigated. The possibility of replacing
some of the iodide promoters by tin compounds has been probed. 相似文献
8.
JF DeFrance S Sands FC Schweitzer L Ginsberg JC Sharma 《Canadian Metallurgical Quarterly》1997,9(4):283-293
The purpose of this article is to deliberate the moral and legal dilemma entailed in the weapon of the labour strike as a pressure tactic on the Israeli Finance Ministry regarding job slots, budgets and, in effect, violating the collective agreement signed by the nurses and impairing patients' treatment, as opposed to refraining from striking and suffering the heavy burden of work, the lack of trained personnel, low wages, and the inability to give patients proper, high quality treatment. 相似文献
9.
10.
Temporal order and functional analysis of mutations within the Fli-1 and p53 genes during the erythroleukemias induced by F-MuLV 总被引:1,自引:0,他引:1
JC Howard S Yousefi G Cheong A Bernstein Y Ben-David 《Canadian Metallurgical Quarterly》1993,8(10):2721-2729
The erythroleukemias induced by Friend murine leukemia virus (F-MuLV) result from the accumulation of a number of genetic changes, including activation of the Fli-1 proto-oncogene and inactivation of the p53 tumor suppressor gene. We have determined the temporal order of mutation of the genes involved in this multistage malignancy, by serial in vivo transplantation of F-MuLV induced primary erythroleukemias into syngenic Balb/c mice. These primary tumors are capable of growing when transplanted into syngenic mice, but die after several days of in vitro culture. From the transplanted tumors grown in syngenic mice, erythropoietin-dependent cell lines were established in culture that are clonally related to cells in the primary tumors. We show that retroviral insertional activation of the Fli-1 ets family member is the first detectable genetic event in F-MuLV induced primary erythroleukemias. Mutations in the p53 gene were observed in the Epo-dependent cell lines but not in the transplanted erythroleukemias used to establish these cell lines in culture. These data suggest that activation of Fli-1 plays an important role in the early stages of F-MuLV-induced leukemia, perhaps by altering the self-renewal probabilities of erythroid progenitor cells and that p53 mutations immortalize these cells, enabling them to grow in vitro in the presence of Epo. 相似文献