全文获取类型
收费全文 | 468篇 |
免费 | 6篇 |
学科分类
工业技术 | 474篇 |
出版年
2021年 | 6篇 |
2019年 | 5篇 |
2018年 | 5篇 |
2016年 | 7篇 |
2015年 | 5篇 |
2014年 | 5篇 |
2013年 | 23篇 |
2012年 | 9篇 |
2011年 | 12篇 |
2010年 | 13篇 |
2009年 | 11篇 |
2008年 | 12篇 |
2007年 | 12篇 |
2006年 | 9篇 |
2005年 | 8篇 |
2004年 | 12篇 |
2003年 | 11篇 |
2002年 | 4篇 |
2001年 | 10篇 |
2000年 | 5篇 |
1999年 | 7篇 |
1998年 | 34篇 |
1997年 | 25篇 |
1996年 | 20篇 |
1995年 | 17篇 |
1994年 | 8篇 |
1993年 | 7篇 |
1992年 | 4篇 |
1991年 | 7篇 |
1990年 | 9篇 |
1989年 | 7篇 |
1988年 | 6篇 |
1987年 | 9篇 |
1986年 | 7篇 |
1985年 | 12篇 |
1984年 | 8篇 |
1983年 | 5篇 |
1982年 | 6篇 |
1981年 | 8篇 |
1979年 | 6篇 |
1978年 | 3篇 |
1977年 | 9篇 |
1976年 | 16篇 |
1975年 | 3篇 |
1974年 | 5篇 |
1973年 | 5篇 |
1972年 | 5篇 |
1969年 | 5篇 |
1968年 | 4篇 |
1966年 | 3篇 |
排序方式: 共有474条查询结果,搜索用时 140 毫秒
1.
Hefei Zhao Xiaoqing Xie Paul Read Benjamin Loseke Stephen Gamet Wenkuan Li Changmou Xu 《International Journal of Food Science & Technology》2021,56(2):825-837
Enriching the micronutrients, selenium (Se) and lithium (Li), in grapes to improve their nutraceutical properties were implemented by foliar application of organic fertiliser rich in Se and Li onto five grape cultivars. The effects of this biofortification on vine vigour, fruit quality, overall micronutrients and phenolic compounds also were investigated. Agronomic biofortification was found greatly increased the Se and Li content in the whole grape by multiple times, meanwhile it did not significantly affect the vine vigour and fruit quality of grapes. However, the biofortification did impact the Ionome (including all the mineral nutrients and trace elements) and phenolic compounds in grapes and this varied among cultivars. This study demonstrated foliar spray of organic Se/Li fertiliser was a very effective strategy to biofortify these micronutrients in grape berries, particularly in the skin, and therefore might be a promising strategy to increase the consumption and awareness of these grapes. 相似文献
2.
An investigation into the effects of pressure (helium gas) on the isothermal fluid behavior includes: (1) the effect of pressure on the rate of melting and coking as evidenced by the rate constants k(melt) and k(coke); (2) the effect of pressure on the energies of activation of melting and coking; (3) the effects of pressure on the characteristic times; (4) the effects of pressure on the maximum isothermal fluidity. Results from the effects of pressure on k(melt) revealed that it was generally the high total sulfur, low nitrogen, low reactives/mineral matter ratio, medium rank coals which show the greatest increase in k(melt), whereas the highest rank coals show the least decrease in k(coke). The energies of activation of melting and coking were not significantly affected by pressure. The investigation also reveals increases or decreases in the respective times of softening, maximum fluidity, resolidification and total time of fluid behavior under isothermal pressurized conditions. There appears the possibility that these shifts may be rank dependent. Additionally, the lower rank coals show the largest relative increase in their fluidities when subjected to pressure. Empirical relationships were derived in order to quantitatively predict the maximum isothermal fluidity for most (fluid) coals at a given pressure. 相似文献
3.
Kahler Christopher W.; Read Jennifer P.; Wood Mark D.; Palfai Tibor P. 《Canadian Metallurgical Quarterly》2003,17(3):226
Structural equation modeling was used to test the mediational role of social environmental selection on alcohol use in cross-sectional samples of 447 students from a rural state university and 421 students from an urban private university. Results showed that male gender, White ethnicity, and sensation seeking were uniquely associated with greater alcohol use. Mediational analyses indicated that socioenvironmental factors (i.e., Greek involvement, friends' approval of drinking/getting drunk) were positively associated with alcohol use and significantly accounted for parts of the effects of ethnicity and sensation seeking, but not gender, on alcohol use. Results suggest that White students and those high on sensation seeking may drink more heavily in college, in part because they select social environments in which alcohol use is encouraged. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
4.
5.
While cellular transformation by small DNA tumour viruses usually involves targeting the product of the p53 tumour suppressor gene by a virally encoded protein, none of the three polyoma virus (Py) specified T antigens have been observed to interact with p53. We show that primary mouse embryo fibroblasts and REF52 cells, which resemble primary cells in requiring co-operating oncogenes for transformation, cannot be transformed by the Py oncogene, middle T-antigen (PyMT), alone. These cells can be transformed by the complete Py early region, which encodes the Py large, middle and small T-antigens. We find that PyMT can transform rodent cells lacking a functional p53 protein (p53 null mouse embryo fibroblasts and DN-REF52 cells which contain a dominant negative p53). In Py transformed REF52 cells (Py-REF52) there is no significant accumulation of p53 protein, as opposed to SV40 transformed REF52 cells (SV-REF52) in which the amount of steady state p53 protein is elevated. However accumulation of p53 is observed following exposure of Py-REF52 cells to u.v. Treatment of Py-REF52 cells with X-rays results in a rapid increase in the levels of the p53-induced proteins p21/WAF1 and MDM2. In untransformed REF52 cells, X-irradiation causes p53 activation, which results in induction of both G1/S and G2/M blocks. In SV-REF52 and DN-REF52 cells, p53 abrogation results in the absence of both the G1/S and G2/M blocks. Only the absence of a G1/S block is observed in Py-REF52 cells exposed to X-irradiation. Together these results indicate that in contrast to most other DNA tumour viruses, Py does not appear to interfere with the DNA damage induced transactivation activities of the p53 protein but absence of a functional p53 protein can mediate transformation by the PyMT oncogene in the absence of other co-operating oncogenes. Possible modes of transformation by Py are discussed. 相似文献
6.
Carl A. Soderstrom Patricia C. Dischinger Gordon S. Smith J.Richard Hebel David R. McDuff David A. Gorelick Timothy J. Kerns Shiu M. Ho Kathleen M. Read 《Accident; analysis and prevention》1997,29(6):715-721
A structured in-depth interview employing standardized criteria was used to determine the prevalence of lifetime and current alcohol dependence (alcoholism) in unselected consecutive patients admitted to a regional Level I trauma center. Of 629 patients, 157 (25.0%) were current alcoholics at the time of injury. An additional 87 (13.8%) were diagnosed as lifetime non-current alcoholics. There was no significant difference in the rates of current alcohol dependence among patients injured in vehicular crashes (23.5%), other unintentional trauma victims (29.3%), and those injured as a result of violence (24.6%). Of BAC + (blood alcohol concentration positive) patients, 54.5% were current alcoholics. However, 14.4% of alcohol-negative patients were also diagnosed as alcohol dependent. 相似文献
7.
8.
Two measures of fracture toughness have been investigated. The first is the Cotterell's essential work of fracture (w
e) which reflects the energy absorbed in the process of localized necking and decohesion occurring within the crack tip region. The second is the familiar critical energy dissipation rate associated with the onset of crack extension and commonly designated by J
c. Total of 48 fracture tests have been performed on thin aluminum double-edge-notched panels and thin compact tension specimens with varying crack size-to-ligament ratios. In a simple experimental procedure it has been established that both measures are equivalent, at least under the plane stress conditions, and that they both represent the fraction of energy which is transmitted through the plastic deformation field into the crack tip region. The ratio essential work of fracture/total work of fracture has been suggested as a quantitative measure of the energy transmission process. Certain predictions are made concerning variations of the energy transmission factor (ETF) during the stable phase of ductile fracture propagation.
On leave from The University of Wisconsin-Milwaukee 相似文献
Résumé On étudie deux mesures de la ténacité à la rupture. La première est le travail essentiel de rupture de Cotterell (w e) qui représente l'énergie absorbée au cours du processus de striction et de décohésion localiseés qui se produit dans la région de l'extrémité d'une fissure. La deuxième est la notion familière de vitesse critique de dissipation d'énergie associée au démarrage de l'extension d'une fissure, qui est couramment représentée par J c. On a procédé à un total de 48 essais de rupture sur des panneaux minces d'aluminium présentant une double entaille de bord, et sur des éprouvettes minces de traction compactes présentant divers rapport de longueur de fissure sur longueurs de ligaments. Par une procédure expérimentale simple, on a établi que les deux mesures de la ténacité sont équivalentes, du moins en état plan de tension, et qu'elles représentent toutes deux la fraction d'énergie qui est transmise au travers du champ de déformation plastique dans la zone de l'extrémité de la fissure. On suggère comme mesure quantitative du processus de transmission d'énergie d'utiliser le rapport travail essentiel de rupture/travail total de rupture. Diverses prédictions sont faites en ce qui concerne les variations du facteur de transmission d'énergie au cours de la phase stable de propagation d'une rupture ductile.
On leave from The University of Wisconsin-Milwaukee 相似文献
9.
Chen Shengyu Kalanat Nasrin Xie Yiqun Li Sheng Zwart Jacob A. Sadler Jeffrey M. Appling Alison P. Oliver Samantha K. Read Jordan S. Jia Xiaowei 《Knowledge and Information Systems》2023,65(8):3223-3250
Knowledge and Information Systems - Physics-based models are widely used to study dynamical systems in a variety of scientific and engineering problems. However, these models are necessarily... 相似文献
10.
Virtual Reality - Virtual reality (VR) is a simulation tool that is being used extensively to study the effects of training and perception. However, several studies have shown that some aspects of... 相似文献