全文获取类型
收费全文 | 1527篇 |
免费 | 3篇 |
学科分类
工业技术 | 1530篇 |
出版年
2021年 | 4篇 |
2019年 | 4篇 |
2016年 | 3篇 |
2015年 | 2篇 |
2014年 | 8篇 |
2013年 | 43篇 |
2012年 | 4篇 |
2011年 | 7篇 |
2010年 | 7篇 |
2009年 | 10篇 |
2008年 | 11篇 |
2007年 | 14篇 |
2006年 | 17篇 |
2005年 | 11篇 |
2004年 | 5篇 |
2003年 | 3篇 |
2002年 | 7篇 |
2001年 | 10篇 |
2000年 | 11篇 |
1999年 | 34篇 |
1998年 | 370篇 |
1997年 | 172篇 |
1996年 | 144篇 |
1995年 | 78篇 |
1994年 | 69篇 |
1993年 | 85篇 |
1992年 | 19篇 |
1991年 | 28篇 |
1990年 | 31篇 |
1989年 | 34篇 |
1988年 | 20篇 |
1987年 | 28篇 |
1986年 | 13篇 |
1985年 | 12篇 |
1984年 | 6篇 |
1983年 | 9篇 |
1982年 | 7篇 |
1981年 | 11篇 |
1980年 | 13篇 |
1979年 | 2篇 |
1978年 | 7篇 |
1977年 | 34篇 |
1976年 | 87篇 |
1975年 | 11篇 |
1974年 | 5篇 |
1973年 | 3篇 |
1972年 | 2篇 |
1971年 | 4篇 |
1970年 | 2篇 |
1955年 | 3篇 |
排序方式: 共有1530条查询结果,搜索用时 15 毫秒
31.
32.
Carl T. Haas Ana Maria Rodriguez Robert Glover Paul M. Goodrum 《Construction Management & Economics》2013,31(6):633-641
Recent studies show the construction industry in the USA is facing a long term labour shortage. Multiskilling has been suggested as a strategy to address this issue by utilizing existing workers more efficiently. Multiskilling decreases the number of workers hired for a project and can improve productivity. Additional benefits include higher income and increased employability of the workforce. To take full advantage of these benefits, the workforce strategy and the planning and scheduling processes of a construction project must be adapted to use multiskilling effectively and efficiently. The multiskilled workforce should be scheduled and organized to maximize the duration of employment for workers, reduce the overall labour requirements and cover the skills combinations required by the project. This research synthesizes and formalizes the methods that successful construction companies are currently applying to implement a multiskilled workforce. A methodology for implementing multiskilling is outlined as well. 相似文献
33.
Ian Mabbett Jon Elvins Catherine Gowenlock Carol Glover Paul Jones Geraint Williams David Worsley 《Progress in Organic Coatings》2014
Near infrared (NIR) is becoming a popular option for rapid cure of coatings in the coil coating industry particularly where fast line speeds are required. The technology has the potential to reduce the cure time of a 20 μm polyester coating on a galvanised steel substrate from around 30 s via conventional heating methods down to <10 s under the lamps. Previous work suggested that the ideal situation in this case is to have a topcoat which is slightly transparent to NIR and an absorbing substrate to heat the coating from the substrate outwards in a two stage process which separates solvent removal from cross linking and film formation. This can be taken further by tinting the primer layer with a pigment that absorbs in the NIR region. In this study spectroscopy was used to show that a coated steel system could appear white in the visible region because of the reflectance of TiO2 but the NIR absorption could be altered by adding absorbing pigments such as carbon black. Lamp settings could be reduced by 20% to achieve equivalent cure with tinted primer systems. The potential degradation in corrosion protection afforded by carbon-black containing pigments at various loadings was assessed for model organic coatings applied to galvanised steel specimens. In situ scanning Kelvin probe studies showed that rates of corrosion-driven coating delamination by cathodic disbondment remained unchanged by pigment loadings of up to 3.5 wt%. 相似文献
34.
A. Glover Bailie Karel Bouzek Petr Lukek Ivo Rouar Anthony A. Wragg 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》1996,66(1):35-40
The solubility of potassium ferrate (K2FeO4) was measured in aqueous solutions of NaOH and KOH of total concentration 12 M containing various molar ratios of KOH:NaOH in the range 12:0 to 3:9. Several analytical methods were tested for the determination of ferrate concentration. The final method chosen consisted of potentiometric titration of the ferrate sample with an alkaline solution of As2O3. The assumption was made that ferrate dissociates in concentrated KOH solutions predominantly to KFeO4−. The solubility constant, S, defined as the product of the molar concentration of the potassium ion, K+, and the ferrate anion, KFeO4−, was found to be 0·044 ± 0·006 mol2 dm−6 for 20°C, 0·093 ± 0·004 mol2 dm−6 for 40°C and 0·15 ± 0·09 mol2 dm−6 for 60°C. From these results the heat of dissolution of K2FeO4 was calculated as −14·3 kJ mol−1. At 60°C the enhanced decomposition of the ferrate at the higher temperature led to a greater deviation in solubility values compared with data for either 20°C or 40°C. 相似文献
35.
<正>悉尼理工大学工程和计算机系系馆位于市区的显赫地段,旨在重新给大学城市校区注入活力,成为悉尼商务中心南端的门户。建筑本体如同一件雕塑作品,迥然和周围的传统建筑风格相异。建筑地上14层,地下4层,设有先进的演讲厅、学术办公室、会议室、学习和研究实验室、营业咖啡厅、娱乐区、停车场,并在隔壁建筑旁设计自行车停靠处。 相似文献
36.
Both extracellular and intracellular calcium (Ca2+) play important roles in hypoxic pulmonary vasoconstriction (HPV) and the vasoconstrictor responses to endogenous pulmonary vasoconstrictor substances, as evidenced by the effect of calcium-channel blockers on these vasoconstrictor responses and the measurement of changes in Ca2+ flux or intracellular Ca2+ concentrations in isolated cells. The more vasoselective the calcium-channel blocker, the greater its effect on pulmonary vasoconstriction. However, these drugs are not selective for the pulmonary vascular bed and are not as potent as pulmonary vasodilators when compared with other vasodilator drugs, including prostaglandin E1, isoproterenol, prostacyclin, or nitroglycerin. Moreover, the primary effect of vasoselective calcium-channel blockers on pulmonary vascular resistance is secondary to the effects of these agents on systemic vascular resistance and cardiac output. Although there is improvement in oxygen delivery, exercise tolerance, and survival in patients with primary pulmonary hypertension who respond to calcium-channel blockers, the response of individual patients to these drugs is difficult to predict because the extent of reversible versus irreversible changes in the pulmonary vasculature is not known. The use of these drugs in patients with chronic hypoxia-induced pulmonary vasoconstriction may be associated with a worsening of ventilation-perfusion mismatching secondary to inhibition of HPV. 相似文献
37.
38.
The kinetics of calcium phosphate crystal growth at the surfaces of proteins and phospholipids has been investigated using free drift and constant composition methods in supersaturated calcium phosphate solutions (relative supersaturations: with respect to hydroxyapatite, HAP, sigma HAP = 15.0, and with respect to octacalcium phosphate, OCP, sigma OCP = 1.9). Fibrinogen and collagen molecules adsorbed at hydrophobic surfaces as well as uncross-linked collagen fibrils induce ion binding and subsequent nucleation of calcium phosphate. The formation of OCP on phosphatidylserine vesicles introduced to highly supersaturated calcium phosphate solutions probably involves the interaction of the calcium ions with the ionized carboxylic groups of the phospholipid. 相似文献
39.
Bovine leukocyte adhesion deficiency--clinical course and laboratory findings in eight affected animals 总被引:1,自引:0,他引:1
KE Müller WE Bernadina HC Kalsbeek A Hoek VP Rutten GH Wentink 《Canadian Metallurgical Quarterly》1994,16(2):65-71
To compare multiple and singleton pregnancies in the treatment of threatened preterm delivery with prolonged intravenous ritodrine, 32 women with multiple pregnancy (26 twins, 6 triplets, 70 fetuses, 30.3 +/- 3.5 weeks) and 51 women with singleton pregnancy (31.3 +/- 2.6 weeks) admitted for threatened preterm delivery without rupture of the membranes were the subjects of a retrospective study of obstetric data, perinatal outcome and maternal adverse effects. Significance was assessed by chi 2 test and Student's t test. Multiple pregnancies were associated with a marked increase in the duration of tocolysis (17.2 +/- 17.3 vs. 7.6 +/- 8.1 days, P < 0.01), incidence of delivery before 37 weeks (87.5 vs. 35.3%, P < 0.01) and incidence of maternal cardiovascular complications (34.4 vs. 4.0%, P < 0.01), including three cases of pulmonary edema. The incidences of delivery before 32 weeks (12.5 vs. 7.8%) and of neonatal death (2.9 vs. 0%) were not significantly different in the two groups. Multiple pregnancies dramatically increased the incidence of maternal adverse effects of prolonged intravenous ritodrine therapy. Neonatal benefit is questionable and was difficult to establish since it was not a randomized study. 相似文献
40.
C Yost GH Farr SB Pierce DM Ferkey MM Chen D Kimelman 《Canadian Metallurgical Quarterly》1998,93(6):1031-1041
Dorsal accumulation of beta-catenin in early Xenopus embryos is required for body axis formation. Recent evidence indicates that beta-catenin is dorsally stabilized by the localized inhibition of the kinase Xgsk-3, utilizing a novel Wnt ligand-independent mechanism. Using a two-hybrid screen, we identified GBP, a maternal Xgsk-3-binding protein that is homologous to a T cell protooncogene in three well-conserved domains. GBP inhibits in vivo phosphorylation by Xgsk-3, and ectopic GBP expression induces an axis by stabilizing beta-catenin within Xenopus embryos. Importantly, antisense oligonucleotide depletion of the maternal GBP mRNA demonstrates that GBP is required for the establishment of the dorsal-ventral axis in Xenopus embryos. Our results define a family of GSK-3-binding proteins with roles in development and cell proliferation. 相似文献