全文获取类型
收费全文 | 5520篇 |
免费 | 90篇 |
国内免费 | 17篇 |
专业分类
电工技术 | 36篇 |
综合类 | 13篇 |
化学工业 | 338篇 |
金属工艺 | 106篇 |
机械仪表 | 69篇 |
建筑科学 | 106篇 |
矿业工程 | 7篇 |
能源动力 | 40篇 |
轻工业 | 134篇 |
水利工程 | 16篇 |
石油天然气 | 24篇 |
无线电 | 163篇 |
一般工业技术 | 266篇 |
冶金工业 | 4027篇 |
原子能技术 | 81篇 |
自动化技术 | 201篇 |
出版年
2022年 | 24篇 |
2021年 | 33篇 |
2020年 | 17篇 |
2019年 | 22篇 |
2018年 | 28篇 |
2017年 | 34篇 |
2016年 | 35篇 |
2015年 | 47篇 |
2014年 | 36篇 |
2013年 | 99篇 |
2012年 | 58篇 |
2011年 | 102篇 |
2010年 | 63篇 |
2009年 | 70篇 |
2008年 | 94篇 |
2007年 | 84篇 |
2006年 | 90篇 |
2005年 | 65篇 |
2004年 | 57篇 |
2003年 | 66篇 |
2002年 | 40篇 |
2001年 | 27篇 |
2000年 | 31篇 |
1999年 | 166篇 |
1998年 | 1357篇 |
1997年 | 724篇 |
1996年 | 442篇 |
1995年 | 280篇 |
1994年 | 226篇 |
1993年 | 276篇 |
1992年 | 63篇 |
1991年 | 70篇 |
1990年 | 57篇 |
1989年 | 49篇 |
1988年 | 56篇 |
1987年 | 78篇 |
1986年 | 43篇 |
1985年 | 47篇 |
1984年 | 26篇 |
1983年 | 19篇 |
1982年 | 25篇 |
1981年 | 33篇 |
1980年 | 35篇 |
1979年 | 17篇 |
1978年 | 16篇 |
1977年 | 88篇 |
1976年 | 132篇 |
1975年 | 12篇 |
1974年 | 8篇 |
1970年 | 8篇 |
排序方式: 共有5627条查询结果,搜索用时 15 毫秒
961.
962.
Pulmonary interstitial emphysema is a well-documented complication of positive-pressure ventilation. However, the occurrence of large sub-pleural air cysts is a less well-known, extreme manifestation of this entity. We present here an infant who developed this complication of pulmonary barotrauma during cardiopulmonary resuscitative efforts. 相似文献
963.
964.
965.
966.
For each of several regions a firm has forecasted a probability distribution of future annual demand, and the plan is to build a single production facility to serve this demand. Each region is served by a simple leased warehouse with a lease cost which is a linear function of capacity. Any regional demand exceeding warehouse capacity is lost. The cost of building the plant is a nonlinear function of its capacity, and the unit cost of producing the product and supplying it to a region is constant. We develop an efficient algorithm based on the Kuhn-Tucker conditions for simultaneously determining the plant and warehouse capacities which will maximize the firm's expected profit. The paper includes a numerical example demonstrating the use of this algorithm. 相似文献
967.
Abnormalities of the systemic atrioventricular (A-V) valve are frequently present in patients with corrected transposition. Systemic A-V valve regurgitation is usually present and may be amenable to operative correction with valve replacement if the regurgitation is caused by normally positioned but deformed valve leaflets or a dilated valve ring, or both. Systemic A-V valve regurgitation secondary to the more common Ebstein-type malformation of the inverted tricuspid valve is an inoperable conditon at present. Displacement of the valve leaflets below the level of the valve ring may be seen in the angiocardiograms of patients with this finding and is the differentiating feature between the two lesions. Ten cases of systemic A-V valve regurgitation in patients with corrected transposition are reviewed to illustrate these features. 相似文献
968.
969.
RH Dean RW Kieffer BM Smith JA Oates JH Nadeau JW Hollifield WD DuPont 《Canadian Metallurgical Quarterly》1981,116(11):1408-1415
Serial renal function studies were performed on 41 patients wtih renovascular hypertension (RVH) secondary to atherosclerotic renal artery disease who had been randomly selected for nonoperative management. In 19 patients, serum creatinine levels increased between 25% and 120%. The glomerular filtration rates dropped between 25% and 50% in 12 patients. Fourteen patients (37%) lost more than 10% of renal length. In four patients (12%), a significant stenosis progressed to total occlusion. Seventeen patients (41%) had deterioration of renal function or loss of renal size that led to operation. One patient required removal of a previously reconstructible kidney. Of the 17 patients with deterioration, 15 had acceptable blood pressure (BP) control during the period of nonoperative observation. Progressive deterioration of renal function in nonoperatively treated patients with atherosclerotic renal artery stenosis and RVH is common, and occurs even in the presence of BP control with drugs. 相似文献
970.
This paper describes and classifies stress measurement techniques used in metal forming to provide research workers with a critical evaluation of usable methods. Eight techniques are considered; pressure transmitting pins, photoelasticity, ridged metallic sheets, paper sheets, split tools, strain gauged tools, orifices in tools and visioplasticity. In addition to these, some new transducer designs using optics and conical pins are presented. These are particularly useful for pressure measurement in hot forming operations. 相似文献