全文获取类型
收费全文 | 762篇 |
免费 | 1篇 |
专业分类
化学工业 | 10篇 |
机械仪表 | 2篇 |
建筑科学 | 1篇 |
能源动力 | 1篇 |
轻工业 | 19篇 |
无线电 | 2篇 |
一般工业技术 | 1篇 |
冶金工业 | 724篇 |
自动化技术 | 3篇 |
出版年
2021年 | 1篇 |
2020年 | 1篇 |
2017年 | 1篇 |
2012年 | 3篇 |
2011年 | 3篇 |
2010年 | 9篇 |
2009年 | 3篇 |
2008年 | 3篇 |
2007年 | 2篇 |
2004年 | 4篇 |
2003年 | 1篇 |
2002年 | 1篇 |
2000年 | 2篇 |
1999年 | 31篇 |
1998年 | 237篇 |
1997年 | 119篇 |
1996年 | 105篇 |
1995年 | 38篇 |
1994年 | 37篇 |
1993年 | 39篇 |
1992年 | 7篇 |
1991年 | 3篇 |
1990年 | 4篇 |
1989年 | 4篇 |
1988年 | 6篇 |
1987年 | 10篇 |
1986年 | 7篇 |
1985年 | 4篇 |
1983年 | 1篇 |
1982年 | 1篇 |
1981年 | 3篇 |
1980年 | 5篇 |
1978年 | 1篇 |
1977年 | 19篇 |
1976年 | 41篇 |
1975年 | 1篇 |
1960年 | 1篇 |
1948年 | 1篇 |
1947年 | 1篇 |
1941年 | 1篇 |
1931年 | 2篇 |
排序方式: 共有763条查询结果,搜索用时 0 毫秒
101.
KJ Yarema LK Mahal RE Bruehl EC Rodriguez CR Bertozzi 《Canadian Metallurgical Quarterly》1998,273(47):31168-31179
The development of chemical strategies for decorating cells with defined carbohydrate epitopes would greatly facilitate studies of carbohydrate-mediated cell surface interactions. This report describes a general strategy for engineering the display of chemically defined oligosaccharides on cell surfaces that combines the concepts of metabolic engineering and selective chemical reactivity. Using a recently described method (Mahal, L. K., Yarema, K. J., and Bertozzi, C. R. (1997) Science 276, 1125-1128), we delivered a uniquely reactive ketone group to endogenous cell surface sialic acid residues by treating cells with the ketone-bearing metabolic precursor N-levulinoylmannosamine (ManLev). The ketone undergoes highly selective condensation reactions with complementary nucleophiles such as aminooxy and hydrazide groups. The detailed quantitative parameters of ManLev metabolism in human and nonhuman-derived cell lines were determined to establish a foundation for the modification of cell surfaces with novel epitopes at defined cell-surface densities. Ketones within the glycoconjugates on ManLev-treated cells were then reacted with synthetic aminooxy and hydrazide-functionalized carbohydrates. The remodeled cells were endowed with novel lectin binding profiles as determined by flow cytometry analysis. The simplicity and generality of this method make it well suited for use in the study of carbohydrate-mediated cell surface interactions. 相似文献
102.
103.
104.
105.
LK Bogush IA Zharakhovich MM Shmelev NE Kubrik SK Rasshivalov 《Canadian Metallurgical Quarterly》1976,71(1):89-93
The single nephron glomerular filtration rate (SNGFR) was determined in superficial (S) and juxtamedullary (JM) nephrons of 10 anesthetized rabbits by the 14C ferrocyanide infusion technique. The length of the proximal tubules and the volume of the glomeruli were also determined for the same nephrons. SNGFR was higher in JM than in S: 28.6 +/- 3.4 versus 22.6 +/- 3.0 nl/min, P less than 0.001. In JM nephrons, glomeruli were larger than in S: 1.3 +/- 0.1 versus 0.9 +/- 0.1 nl, P less than 0.001, whereas there was no difference between proximal tubule length in either category (s, 8.7 +/- 0.3 and JM, 8.9 +/- 0.5 mm). In 6 out of 8 animals, SNGFR was significantly correlated to glomerular volume. Lack of correlation was observed between SNGFR and length of proximal tubule in all animals but one. These results show that the rabbit, as well as small rodents and the dog, has a higher SNGFR in juxtamedullary than superficial glomeruli. Although this functional difference is not related to the length of the proximal tubule in each individual animal, the ratio between the mean SNGFR value and the mean length of the proximal tubule in superficial rabbit nephrons is similar to the ratio found in other species. 相似文献
106.
Transillumination of the skull in infants is a simple technique which can be used to detect several major abnormalities of the central nervous system. The usefulness of transillumination has been limited, however, by the lack of standard techniques for its performance and by the absence of normal values, especially in premature infants. In healthy premature infants, there is a progressive increase in transillumination with increasing gestational age over three sites--the anterior fontanelle, the frontotemporal fossa, and the parieto-occipital eminence. 相似文献
107.
LK Katosova 《Canadian Metallurgical Quarterly》1977,13(3):403-404
Studies have been made on ontogenetic changes in the activity of succinic dehydrogenase, alpha-glycerophosphate dehydrogenase and acid phosphatase from the lymphocytes of rabbit blood. It was found that maturation of alpha-glycerophosphate dehydrogenase takes place at later stages as compared to other enzymes. The activity of succinic dehydrogenase gradually decreases. Acid phosphatase activity, being rather high in very young animals, also decreases with ageing. 相似文献
108.
PC Berquin JN Giedd LK Jacobsen SD Hamburger AL Krain JL Rapoport FX Castellanos 《Canadian Metallurgical Quarterly》1998,50(4):1087-1093
Clinical, neuroanatomic, neurobehavioral, and functional brain-imaging studies suggest a role for the cerebellum in cognitive functions, including attention. However, the cerebellum has not been systematically studied in attention-deficit hyperactivity disorder (ADHD). We quantified the cerebellar and vermal volumes, and the midsagittal areas of three vermal regions, from MRIs of 46 right-handed boys with ADHD and 47 matched healthy controls. Vermal volume was significantly less in the boys with ADHD. This reduction involved mainly the posterior inferior lobe (lobules VIII to X) but not the posterior superior lobe (lobules VI to VII). These results remained significant even after adjustment for brain volume and IQ. A cerebello-thalamo-prefrontal circuit dysfunction may subserve the motor control, inhibition, and executive function deficits encountered in ADHD. 相似文献
109.
110.