全文获取类型
收费全文 | 823篇 |
免费 | 3篇 |
学科分类
工业技术 | 826篇 |
出版年
2020年 | 1篇 |
2019年 | 3篇 |
2018年 | 1篇 |
2017年 | 1篇 |
2015年 | 2篇 |
2014年 | 4篇 |
2013年 | 18篇 |
2012年 | 7篇 |
2011年 | 8篇 |
2010年 | 2篇 |
2009年 | 7篇 |
2008年 | 5篇 |
2007年 | 5篇 |
2006年 | 5篇 |
2005年 | 2篇 |
2004年 | 2篇 |
2003年 | 9篇 |
2002年 | 3篇 |
1999年 | 18篇 |
1998年 | 206篇 |
1997年 | 117篇 |
1996年 | 85篇 |
1995年 | 37篇 |
1994年 | 44篇 |
1993年 | 41篇 |
1992年 | 10篇 |
1991年 | 18篇 |
1990年 | 9篇 |
1989年 | 9篇 |
1988年 | 7篇 |
1987年 | 12篇 |
1986年 | 13篇 |
1985年 | 11篇 |
1983年 | 2篇 |
1982年 | 5篇 |
1981年 | 5篇 |
1980年 | 6篇 |
1978年 | 2篇 |
1977年 | 21篇 |
1976年 | 34篇 |
1975年 | 9篇 |
1974年 | 2篇 |
1973年 | 5篇 |
1972年 | 5篇 |
1971年 | 4篇 |
1970年 | 1篇 |
1969年 | 2篇 |
1955年 | 1篇 |
排序方式: 共有826条查询结果,搜索用时 0 毫秒
821.
Roger D.H. Warburton 《International Journal of Project Management》2011,29(8):1082-1090
This paper proposes a formal method for including time dependence into Earned Value (EV) management. The model requires three parameters, which map directly to the fundamental “triple constraint” of scope, cost, and schedule: the reject rate of activities, the cost overrun parameter, and the time to repair the rejected activities. Time dependent expressions for the planned value, earned value, and actual cost are derived, along with the cost performance index (CPI) and schedule performance index (SPI). The model is built on the well-established Putnam–Norden–Rayleigh (PNR) labor rate profile, which is a useful representation for large software projects. We apply the model to a well-known software dataset, demonstrating how to estimate the project's final cost, which converges faster to the correct answer with less variability than standard Estimate-at-Completion (EAC) calculations. The model also accurately predicts the required revised labor profile and the new schedule. 相似文献
822.
The concept of the equilibrium relative humidity (e.r.h.) of a product as a measure of storage potential is discussed. It is stressed that whilst moisture content gives an estimate of the amount of water in a product it does not, by itself, indicate the biological activity, or potential activity, of the product. Graphs are presented giving the e.r.h., at a given moisture content, for different temperatures of a soft wheat, barley, American yellow dent maize, flint maize grown in England, and tick beans (Vicia faba L.). 相似文献
823.
AM Alino HD Perry AJ Kanellopoulos ED Donnenfeld EK Rahn 《Canadian Metallurgical Quarterly》1998,105(6):1120-1123
PURPOSE: The authors reviewed their experience with total conjunctival flaps (TCF) and partial conjunctival flaps (PCF) for the past 5 years in 61 patients. METHODS: Forty-eight patients had TCF and 13 had PCF. Diagnoses for surgery included severe bullous keratopathy for chronic graft failure (not candidates for keratoplasty) (19), herpes zoster ophthalmicus (7), chronic ulcerative keratitis (14), neurotrophic keratitis (2), and herpes simplex keratitis (9). RESULTS: There were seven complications. Four flap retractions occurred in the TCF group, requiring resuturing in two. Three complications occurred in the PCF group. One patient had two flap retractions and recurrent ulceration, requiring tarsorrhaphy. One patient with PCF suffered a perforation after flap retraction, necessitating penetrating keratoplasty. CONCLUSION: The authors believe conjunctival flaps are underused and should be considered seriously for bullous keratopathy, neurotrophic keratitis, recalcitrant keratitis, and persistent nonhealing epithelial defects. 相似文献
824.
825.
826.
S Basavappa SF Pedersen NK J?rgensen JC Ellory EK Hoffmann 《Canadian Metallurgical Quarterly》1998,79(3):1441-1449
Arachidonic acid or its metabolites have been implicated in the regulatory volume decrease (RVD) response after hypotonic cell swelling in some mammalian cells. The present study investigated the role of arachidonic acid (AA) during RVD in the human neuroblastoma cell line CHP-100. During the first nine minutes of hypo-osmotic exposure the rate of 3H-arachidonic acid (3H-AA) release increased to 250 +/- 19% (mean +/- SE, n = 22) as compared with cells under iso-osmotic conditions. This release was significantly inhibited after preincubation with AACOCF3, an inhibitor of the 85-kDa cytosolic phospholipase A2 (cPLA2). This indicates that a PLA2, most likely the 85-kDa cPLA2 is activated during cell swelling. In contrast, preincubation with U73122, an inhibitor of phospholipase C, did not affect the swelling-induced release of 3H-AA. Swelling-activated efflux of 36Cl and 3H-taurine were inhibited after preincubation with AACOCF3. Thus the swelling-induced activation of cPLA2 may be essential for stimulation of both 36Cl and 3H-taurine efflux during RVD. As the above observation could result from a direct effect of AA or its metabolite leukotriene D4 (LTD4), the effects of these agents were investigated on swelling-induced 36Cl and 3H-taurine effluxes. In the presence of high concentrations of extracellular AA, the swelling-induced efflux of 36Cl and 3H-taurine were inhibited significantly. In contrast, addition of exogenous LTD4 had no significant effect on the swelling-activated 36Cl efflux. Furthermore, exogenous AA increased cytosolic calcium levels as measured in single cells loaded with the calcium sensitive dye Fura-2. On the basis of these results we propose that cell swelling activates phospholipase A2 and that this activation via an increased production of AA or some AA metabolite(s) other than LTD4 is essential for RVD. 相似文献