全文获取类型
收费全文 | 87701篇 |
免费 | 1100篇 |
国内免费 | 408篇 |
专业分类
电工技术 | 806篇 |
综合类 | 2322篇 |
化学工业 | 12302篇 |
金属工艺 | 4822篇 |
机械仪表 | 3084篇 |
建筑科学 | 2494篇 |
矿业工程 | 574篇 |
能源动力 | 1223篇 |
轻工业 | 4021篇 |
水利工程 | 1315篇 |
石油天然气 | 352篇 |
武器工业 | 1篇 |
无线电 | 9479篇 |
一般工业技术 | 16908篇 |
冶金工业 | 3162篇 |
原子能技术 | 270篇 |
自动化技术 | 26074篇 |
出版年
2022年 | 45篇 |
2021年 | 67篇 |
2020年 | 58篇 |
2019年 | 81篇 |
2018年 | 14522篇 |
2017年 | 13446篇 |
2016年 | 10050篇 |
2015年 | 671篇 |
2014年 | 359篇 |
2013年 | 490篇 |
2012年 | 3311篇 |
2011年 | 9651篇 |
2010年 | 8450篇 |
2009年 | 5736篇 |
2008年 | 6959篇 |
2007年 | 7973篇 |
2006年 | 282篇 |
2005年 | 1372篇 |
2004年 | 1245篇 |
2003年 | 1271篇 |
2002年 | 648篇 |
2001年 | 157篇 |
2000年 | 249篇 |
1999年 | 137篇 |
1998年 | 148篇 |
1997年 | 105篇 |
1996年 | 132篇 |
1995年 | 66篇 |
1994年 | 65篇 |
1993年 | 62篇 |
1992年 | 58篇 |
1991年 | 58篇 |
1989年 | 43篇 |
1988年 | 41篇 |
1987年 | 37篇 |
1986年 | 38篇 |
1985年 | 39篇 |
1984年 | 54篇 |
1983年 | 48篇 |
1982年 | 41篇 |
1981年 | 36篇 |
1980年 | 36篇 |
1968年 | 45篇 |
1966年 | 45篇 |
1965年 | 44篇 |
1959年 | 35篇 |
1958年 | 37篇 |
1957年 | 36篇 |
1955年 | 63篇 |
1954年 | 68篇 |
排序方式: 共有10000条查询结果,搜索用时 10 毫秒
101.
Sebastián Bruque-Cámara Alfonso Vargas-Sánchez M. Jesús Hernández-Ortiz 《欧洲信息系统杂志》2004,13(2):133-146
The aim of this paper is to propose new organizational factors that might explain the differences in the extent and the speed of IT adoption. With this in mind, we carried out an analysis of 16 cases in the pharmaceutical distribution sector in Spain. The results indicate that there are certain intangible assets that favour the introduction and development of IT. Among these are a frank and fluid communication between departments and members of the organization, low levels of conflict, the explicit support of top management towards IT adoption and learning and creative skills of IT-staff. In addition to these factors, we found others that we propose as catalysts of IT adoption. Among these we might mention the special relationship between the member-clients and the company in the case of cooperative firms. 相似文献
102.
103.
104.
Ian Haywood 《Cities》1985,2(3):186-197
Khartoum is the capital of a country whose creation resulted more from colonial politicians' desires for straight boundaries than from local social or political realities. This profile traces Khartoum's history of growth and planning legislation since its establishment as an administrative capital at the turn of the century. The city, developed from three separate towns, grew rapidly after independence as administrative functions grew and industrial development started. However, lack of an effective mechanism for planning and control of the city's growth has meant that a pattern of sprawling low-density land uses has developed, with inadequate services and deteriorating environmental standards. What planning control does exist operates through land-use zoning and building byelaws, though often arbitrarily applied. Planning problems are exacerbated by high population growth rates and national economic problems. 相似文献
105.
Lewinsohn Peter M.; Roberts Robert E.; Seeley John R.; Rohde Paul; Gotlib Ian H.; Hops Hyman 《Canadian Metallurgical Quarterly》1994,103(2):302
In a prospective study of adolescent depression, adolescents (N?=?1,508) were assessed at Time 1 and after 1 yr (Time 2) on psychosocial variables hypothesized to be associated with depression. Most psychosocial variables were associated with current (n?=?45) depression. Formerly depressed adolescents (n?=?217) continued to differ from never depressed controls on many of the psychosocial variables. Many of the depression-related measures also acted as risk factors for future depression (n?=?112), especially past depression, current other mental disorders, past suicide attempt, internalizing behavior problems, and physical symptoms. Young women were more likely to be, to become, and to have been depressed. Controlling for the psychosocial variables eliminated the gender difference for current and future but not for past depression. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
106.
A trade-off analysis on the cost and system packaging metrics of an electronic product aimed at the commercial/retail industry has been carried out. By comparing the system cost and packaging metrics with those of comparable consumer products, we have determined that there is opportunity for significant cost, size, and weight reduction of the overall electronics packaging system. These include the use of fine pitch IC packages, smaller discrete components, denser PCB wiring technology, double sided IC package surface mount, surface mount connectors, and improved plastics for the product housing. The analysis concluded that PCB area reduction of 40%, using a single PCB instead of three boards, reduction in board cost of over 50% and product weight reduction of over 28% are possible using available technologies. 相似文献
107.
Terasa Kubala Baldev Gambhir S. Ian Borst 《Drug development and industrial pharmacy》1993,19(7):749-757
A high performance liquid chromatography method is described for the determination of diclofenac sodium, its related compounds and degradation products in commercial sources of raw materials and solid dosage forms. This method is specific, accurate and stability indicating. The method employs a reverse-phase octylsilane (C18) column with a mobile phase composed of acetonitrile/methanol/pic B-6 (25:25:50) and detection at 229 nm. The method resolves six principal related compounds with quantitation in the range 0.3-1.5%. Assay recoveries by spiking commercial formulations with diclofenac sodium were 99.64 ± 1.30%. Drug content in several commercial formulations are reported. Accelerated stability tests were conducted on raw materials and drug products and 1-(2,6-dichlorophenyl)-2-indolin-2-one was identified for the first time as a degradation product in solid dosage forms which are stressed under humidity and heat. 相似文献
108.
Lalumiére Martin L.; Quinsey Vernon L.; Beninger Richard D.; Barsetti Ian; Earls Christopher M. 《Canadian Metallurgical Quarterly》1993,34(4):461
Discusses controversies surrounding the work of B. F. Skinner's influence on various theories of human and animal behavior. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
109.
Frantz Rowe 《欧洲信息系统杂志》2006,15(3):244-248
110.