全文获取类型
收费全文 | 488366篇 |
免费 | 7512篇 |
国内免费 | 2515篇 |
专业分类
电工技术 | 9468篇 |
技术理论 | 4篇 |
综合类 | 1391篇 |
化学工业 | 71895篇 |
金属工艺 | 17308篇 |
机械仪表 | 14759篇 |
建筑科学 | 13273篇 |
矿业工程 | 1902篇 |
能源动力 | 13856篇 |
轻工业 | 46736篇 |
水利工程 | 4296篇 |
石油天然气 | 6099篇 |
武器工业 | 147篇 |
无线电 | 64036篇 |
一般工业技术 | 90951篇 |
冶金工业 | 91379篇 |
原子能技术 | 8030篇 |
自动化技术 | 42863篇 |
出版年
2022年 | 2848篇 |
2021年 | 4455篇 |
2020年 | 3290篇 |
2019年 | 3830篇 |
2018年 | 6028篇 |
2017年 | 6104篇 |
2016年 | 6409篇 |
2015年 | 4771篇 |
2014年 | 7937篇 |
2013年 | 22994篇 |
2012年 | 13047篇 |
2011年 | 18018篇 |
2010年 | 14214篇 |
2009年 | 16002篇 |
2008年 | 16841篇 |
2007年 | 16662篇 |
2006年 | 15213篇 |
2005年 | 13641篇 |
2004年 | 12949篇 |
2003年 | 13063篇 |
2002年 | 11993篇 |
2001年 | 12694篇 |
2000年 | 11744篇 |
1999年 | 12743篇 |
1998年 | 31334篇 |
1997年 | 21808篇 |
1996年 | 16607篇 |
1995年 | 12539篇 |
1994年 | 11065篇 |
1993年 | 10860篇 |
1992年 | 7673篇 |
1991年 | 7298篇 |
1990年 | 7007篇 |
1989年 | 6626篇 |
1988年 | 6444篇 |
1987年 | 5303篇 |
1986年 | 5154篇 |
1985年 | 5994篇 |
1984年 | 5379篇 |
1983年 | 5115篇 |
1982年 | 4696篇 |
1981年 | 4694篇 |
1980年 | 4446篇 |
1979年 | 4112篇 |
1978年 | 3801篇 |
1977年 | 4561篇 |
1976年 | 6088篇 |
1975年 | 3179篇 |
1974年 | 3060篇 |
1973年 | 3074篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
951.
Uraoka Y. Eriguchi K. Tamaki T. Tsuji K. 《Semiconductor Manufacturing, IEEE Transactions on》1994,7(3):293-297
Gate oxide damage by plasma processing was evaluated using structures with various antenna lengths. The gate oxide damage by plasma processing was found to be monitored quantitatively by measuring the charge to breakdown, QBD. From the QBD measurements, we have confirmed that the degradation occurs during overetching, not in main etching. Plasma current was calculated from the decrease of QBD during the etching. The breakdown spot in the gate oxide was detected by photon emission and TEM. The LOCOS structure plays an important role for the degradation by plasma damage. In this paper, it is demonstrated that the QBD method is effective for realizing a highly reliable process against plasma damage 相似文献
952.
Surveys show that, although there is generally high awareness of the legal requirement to conform with the EMC Directive, confusion and uncertainty remain with regard to both the legal and technical issues. The EMC Directive will be fully implemented in all member states of the EU from 1 January 1996. It is imperative to recognise that after this date it will be a criminal offence to market electrical/electronic products that do not conform with its protection requirements. The precise details of how enforcement will be carried out in each member state are unclear. The guidance given to the; enforcement bodies from the DTI is to help companies to conform rather than to prosecute. The overriding issue is that, whatever the level of enforcement, manufacturers have a duty in law to demonstrate conformance for their products. The process of demonstrating conformance also requires clarification. It is how to demonstrate that products conform that is the stumbling block for many companies. The author discusses the routes to compliance and planning for it. Case studies are briefly outlined and the growth areas in EMC compliance are discussed. A sample showing suggested contents for a technical construction file is also given 相似文献
953.
Lucyszyn S. Stewart C. Robertson I.D. Aghvami A.H. 《Electronics & Communication Engineering Journal》1994,6(2):69-76
Introduces the basic technologies that are associated with measurements of monolithic microwave integrated circuits. The use of test fixtures and wafer probe stations at ambient room temperature is reviewed and their role at thermal and cryogenic temperatures is discussed. With the increasing need for performing non-invasive measurements, advances in experimental field probing techniques are explored 相似文献
954.
This paper looks first at the background to the development of intelligent networking concepts and then tracks this development to the advanced intelligent networks (AINs) of today. The network architecture and basic nodal functions are explained, and a brief review given of the essential intelligent network building blocks, namely the IN (intelligent network) call model and the enhanced CCITT No.7 signalling system. Typical intelligent network services are examined and the tutorial finishes with a review of the latest IN standards 相似文献
955.
J Jassem H Karnicka-M?odkowska C van Pottelsberghe M van Glabbeke MA Noseda A Ardizzoni F Gozzelino A Planting N van Zandwijk 《Canadian Metallurgical Quarterly》1993,(12):1720-1722
26 previously treated patients with progressive recurrent small cell lung cancer (SCLC) were given vinorelbine (Navelbine), 30 mg/m2 weekly. All patients had responded to first-line chemotherapy and were off therapy for at least 3 months. Partial response was observed in 4 out of 25 eligible patients (16%; 95% confidence interval 4-36%), stable disease in 7 patients and progression in 12 patients. The limiting toxicity was a non-cumulative leucopenia (80%, 32% WHO grade 3-4). Reaction at the site of injection was observed in 5 patients, causing treatment discontinuation in 2 cases. Other non-haematological toxicities were moderate. These results suggest acceptable toxicity and some antitumour activity of vinorelbine in pretreated SCLC patients. 相似文献
956.
957.
Using ion exchange chromatography and an ATP-dependent actin precipitation step, we have isolated three myosin-I isozymes that, together, account for most of the K+EDTA-ATPase activity recovered from extracts of Dictyostelium. The two major myosin-I isozymes, present in approximately equal amounts, had apparent molecular masses of 125 kDa on SDS gels and have been identified by amino acid sequence analysis as the products of the Dictyostelium myosin-IB (DMIB) and myosin-ID (DMID) genes. DMIB, with a specific K+EDTA-ATPase activity 10-fold higher than DMID, was responsible for most of the activity in cell extracts. The third isozyme, present in low amounts, had an apparent molecular mass of 137 kDa on SDS gels and is too large to be the product of any of the known myosin-I genes. DMIB eluted from DE53 cellulose columns as two distinct peaks (II and III). Addition of the phosphatase inhibitor okadaic acid to the extraction buffer increased the fraction of DMIB recovered from growth phase cells in peak III from 35 to 70%. DMIB isolated from peak III, but not from peak II, displayed a significant level of actin-activated MgATPase activity. These results indicate that peak III represents a phosphorylated, actin-activatable form of DMIB. 相似文献
958.
959.
Fracture toughness and fatigue crack propagation (FCP) of plain and modified anhydride-cured epoxy resin (EP) were studied at ambient temperature. Liquid carboxyl-terminated acrylonitrile-butadiene (CTBN) and silicon (SI) rubber dispersions were used as tougheners for the EP. The morphology of the modified EP was characterized by dynamic mechanical analysis (DMA) and by scanning electron microscopy (SEM). The fracture toughness, Kc, of the compositions decreased with increasing deformation rate. Kc of the EP was slightly improved by CTBN addition and practically unaffected by incorporation of the SI dispersion when tests were performed at low cross-head speed, v. Both modifiers improved Kc at high v, and also the resistance to FCP, by shifting the curves to higher stress intensity factor ranges, ΔK, by comparison with the plain EP. It was established that both fracture and fatigue performance rely on the compliance, JR, at the rubbery plateau, and thus on the apparent molecular mass between crosslinks, Mc. The failure mechanisms were less dependent upon the loading mode (fracture, fatigue), but differed basically for the various modifiers. Rubber-induced cavitation and shear yielding of the EP were dominant for CTBN, whereas crack bifurcation and branching controlled the cracking in SI-modified EP. The simultaneous use of both modifiers resulted in a synergistic effect for both the fracture toughness at high deformation rate and the FCP behavior. 相似文献
960.
This article describes a test piece that minimizes the spread of the results of testing of composite materials on a metal base by extension in the direction of a reinforcing fiber and, from the results, determines the mechanical properties of intermediate and finished products made of these materials.Translated from Izmeritel'naya Tekhnika, No. 10, pp. 39–40, October, 1993. 相似文献