全文获取类型
收费全文 | 1824篇 |
免费 | 16篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 5篇 |
综合类 | 2篇 |
化学工业 | 62篇 |
金属工艺 | 8篇 |
机械仪表 | 7篇 |
建筑科学 | 19篇 |
矿业工程 | 2篇 |
能源动力 | 23篇 |
轻工业 | 11篇 |
水利工程 | 2篇 |
石油天然气 | 1篇 |
无线电 | 71篇 |
一般工业技术 | 64篇 |
冶金工业 | 1536篇 |
原子能技术 | 12篇 |
自动化技术 | 17篇 |
出版年
2022年 | 3篇 |
2021年 | 5篇 |
2020年 | 7篇 |
2019年 | 5篇 |
2018年 | 11篇 |
2017年 | 3篇 |
2016年 | 9篇 |
2015年 | 5篇 |
2014年 | 3篇 |
2013年 | 12篇 |
2012年 | 13篇 |
2011年 | 13篇 |
2010年 | 9篇 |
2009年 | 10篇 |
2008年 | 18篇 |
2007年 | 13篇 |
2006年 | 11篇 |
2005年 | 10篇 |
2004年 | 14篇 |
2003年 | 14篇 |
2002年 | 7篇 |
2001年 | 8篇 |
2000年 | 6篇 |
1999年 | 48篇 |
1998年 | 429篇 |
1997年 | 252篇 |
1996年 | 182篇 |
1995年 | 85篇 |
1994年 | 97篇 |
1993年 | 88篇 |
1992年 | 30篇 |
1991年 | 32篇 |
1990年 | 26篇 |
1989年 | 15篇 |
1988年 | 20篇 |
1987年 | 31篇 |
1986年 | 27篇 |
1985年 | 18篇 |
1984年 | 3篇 |
1983年 | 7篇 |
1982年 | 17篇 |
1981年 | 16篇 |
1980年 | 19篇 |
1979年 | 3篇 |
1978年 | 5篇 |
1977年 | 58篇 |
1976年 | 110篇 |
1974年 | 2篇 |
1966年 | 2篇 |
1954年 | 2篇 |
排序方式: 共有1842条查询结果,搜索用时 406 毫秒
91.
Plasma-chemical etching of silicon and silicon compounds is reviewed. It is shown that present data indicates that fluorine atoms and molecules are the main particles responsible for etching of silicon and that atomic fluorine is the main active particle for etching of silicon dioxide. Insufficient data exists to establish the contribution of charged and excited states to the etching of silicon and its compounds but oxygen atoms and molecules are seen to have a strong influence and fluorocarbon radicals can passivate the surface by forming polymer films. 相似文献
92.
93.
LS Cherkasova GG Vereshchako TM Mironova VA Novik MIu Ta?ts GF Tsykhun VG Fomichenko 《Canadian Metallurgical Quarterly》1977,49(4):15-18
Intensity of glycolysis was studied under conditions of immobilization stress and adrenalectomy as well as with administration of adrenaline and hydrocortisone. The processes of aerobic glycolysis, activity of enzymes of the tricarboxylic acid cycle and mitochondria respiratory chain, content of total, free and protein-bound glycogen, glucose-I-phosphate, glucose-6-phosphate, pyruvate, alpha-ketoglutarate, cytrate and macroergs in the brain are shown to depend on the level of adrenal hormones producing a multilateral effect on a series of energy metabolism links. 相似文献
94.
95.
96.
97.
L Zardi LS Vincent A Barbin R Montesano GP Margison 《Canadian Metallurgical Quarterly》1977,3(3-4):183-188
DNA repair was measured in human fibroblasts, mouse C3H 10 T 1/2 fibroblsts and rat hepatocytes by the non-semi-conservative incorporation of [3H]-TdR during DNA repair synthesis using liquid scintillation techniques. Confluent monolayers of these cells grown on cover slips were exposed to split doses (125 or 250 microgram/ml) of the mutagenic and carcinogenic alkylating agent MNU and DNA repair synthesis compared with that produced by a single dose (500 microgram/ml). No significant difference in DNA repair capacity was detected in the three cell lines treated with a single dose or split doses of MNU. 相似文献
98.
This paper presents a M6800 microprocessor based hardware monitor for measuring certain selected parameters of the EC-1030 computer system. The motivation for this work was to get an insight into the operation of the system under the present work load and use these results towards improvement and design studies. The three main classes of quantitative indices of computer system performance/productivity, responsiveness and use have been measured using hardware and software tools. This paper describes the hardware monitor design and discusses the measurements made. 相似文献
99.
In this paper a conceptual framework for the analysis of economiclearning is developed. Economic learning, by analogy with organizationallearning, results in the development of economic competences,or capabilities, shared between firms, which rest on a foundationof economic resources, from which value is generated, and economicroutines, through which resources are utilized. It is the mobilityof resources, and their exchange and production dynamics, alongevolutionary pathways, which underpins the plausibility of anotion of economic learning. The paper elaborates this frameworkas a resource-based view (RBV) of the economyas a whole, as an extension of the RBV of the firm. Such a frameworkcaptures the dynamics of exchange and circulation of technologies,know-how and intangible assets, as well as of tangible assetsand capital goods; it is concerned with investment behaviorby entrepreneurs rather than with the behavior of producersand consumers in goods and services markets. Within this resourceeconomy framework, it is possible to generate an account ofthe resource dynamics that underpin production of goods andservicesincluding resource propagation, diffusion, imitation,replication and recombination. These processes encompass evolutionarypressures, experienced through resource variation, selectionand retention. Entrepreneurial initiatives take the form ofresource recombinations, while resource innovation capturesthe creation of new economic resources, such as technologicalstandards. Such a perspective brings into focus the resourcespecialization and configurations that drive real economies,within firms and between firms, that translates into enhancedor diminished performance of the economy as a whole. 相似文献
100.
The pebble bed modular reactor (PBMR) is a new generation high temperature gas-cooled reactor, making use of spherical fuel elements. The spent fuel and partially burnt fuel (called used fuel) is stored in large storage tanks. This paper presents the cooling design of the storage tanks, with special emphasis on its passive cooling ability.For corrosion protection, the tanks are cooled with a closed loop active system, however, passive cooling is seen as the ultimate cooling mode for the storage tanks. If the active cooling fails, the flow automatically bypasses the active system and passive cooling takes over. The active cooling is thus not safety-related; rather its purpose is for investment protection.The storage tank design with its longitudinal internal cooling pipes has a good passive cooling ability. The layout of the tank concrete cubicle ensures that cooling air can flow only in the desired direction. Computational fluid dynamics (CFD) analyses have been done for various heat load scenarios inside the tank. Passive cooling exists for tanks with a low spent fuel fill level with heat load below 25 kW up to a tank containing a full PBMR core (used fuel) with heat load of 640 kW. For all scenarios, the maximum fuel temperature is below 400 °C.A method was developed to calculate the passive cooling characteristics of the tank at a fraction of the time it takes CFD by using the pipe network simulation software Flownex. The method was also used to analyze transient passive cooling events and showed flow phenomenon similar to what CFD analyses have predicted.A small-scale two-dimensional representation of the storage tank and cubicle layout has been built. This experiment demonstrates the passive cooling ability of the tank. It also proved the flow characteristics that were predicted by the CFD and Flownex analyses.It has been shown through diverse techniques that the fuel inside the tanks can be cooled passively. There are still a few aspects which need to be explored in more detail, but overall it can be said that passive cooling of the PBMR spent and used fuel in bulk storage tanks is viable. 相似文献