全文获取类型
收费全文 | 1177篇 |
免费 | 7篇 |
专业分类
电工技术 | 4篇 |
化学工业 | 47篇 |
金属工艺 | 9篇 |
机械仪表 | 11篇 |
建筑科学 | 20篇 |
能源动力 | 22篇 |
轻工业 | 38篇 |
水利工程 | 5篇 |
石油天然气 | 1篇 |
无线电 | 42篇 |
一般工业技术 | 62篇 |
冶金工业 | 870篇 |
原子能技术 | 5篇 |
自动化技术 | 48篇 |
出版年
2021年 | 6篇 |
2019年 | 5篇 |
2018年 | 5篇 |
2017年 | 4篇 |
2016年 | 7篇 |
2015年 | 5篇 |
2014年 | 5篇 |
2013年 | 23篇 |
2012年 | 9篇 |
2011年 | 15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 | 35篇 |
1998年 | 268篇 |
1997年 | 142篇 |
1996年 | 121篇 |
1995年 | 54篇 |
1994年 | 45篇 |
1993年 | 46篇 |
1992年 | 9篇 |
1991年 | 10篇 |
1990年 | 13篇 |
1989年 | 11篇 |
1988年 | 12篇 |
1987年 | 17篇 |
1986年 | 14篇 |
1985年 | 16篇 |
1984年 | 8篇 |
1983年 | 6篇 |
1982年 | 7篇 |
1981年 | 11篇 |
1980年 | 5篇 |
1979年 | 6篇 |
1977年 | 28篇 |
1976年 | 57篇 |
1975年 | 4篇 |
1974年 | 5篇 |
1973年 | 5篇 |
1972年 | 5篇 |
1969年 | 5篇 |
1968年 | 4篇 |
排序方式: 共有1184条查询结果,搜索用时 15 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.
Early patterning of prelimbic cortical axons to the striatal patch compartment in the neonatal mouse
LK Nisenbaum SM Webster SL Chang KD McQueeney JJ LoTurco 《Canadian Metallurgical Quarterly》1998,20(2-3):113-124
The striatum receives excitatory input from virtually the entire cerebral cortex. In the adult, this input is segregated into two functionally distinct compartments of the striatum, the patch (striosome) and matrix regions. This study determined whether the patterning of corticostriatal afferents from the prelimbic cortex to the striatal patch compartment develops during the early period of collateral formation or instead at the time of peak synaptogenesis. Initial formation of corticostriatal axon collaterals was observed by embryonic day (E) 19. Quantification of corticostriatal collaterals revealed a significant increase in the number and complexity of collateral branches at postnatal day 6 as compared to E19. Concomitant with the increase in collateral branching, a heterogeneous pattern of collateralization consisting of parallel rows of corticostriatal collaterals was observed in the medial striatum. In addition to the rows, clusters of corticostriatal axons occurred more laterally. These clusters colocalized with patches of dense tyrosine hydroxylase-positive fibers, a marker for the striatal patch compartment in the neonatal mouse. Together, these data indicate that corticostriatal patterning occurs during the period of early axon collateralization resulting in a segregation of corticostriatal axon collaterals from the prelimbic cortex to the striatal patch compartment. 相似文献
3.
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
4.
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
5.
A Notghi R Hutchinson D Kumar NB Smith LK Harding 《Canadian Metallurgical Quarterly》1994,35(7):976-981
Segmental colonic transit has been measured in 101 patients. Two MBq of 111Indium absorbed on resin pellets and encapsulated in an enteric coated capsule was given at 7 00 am. Hourly images during the first day, and three images during each subsequent day were acquired for up to three days. Using all scan and patient data the scans were categorised in one of the five patterns of colonic transit: normal, rapid, right delay, left delay, or generalised delay. The geometric centres and per cent activity at each time point was compared between the five groups of colonic transit patients to find the best time for imaging and so to distinguish the five groups. During the first day, early images did not help in diagnosis of patterns of transit, however, in the later images (six hours onwards after the ingestion of the activity) the rapid transit groups could be identified. Images at 27 and 51 hours were both required to distinguish all five groups of patients from each other. Only in the 'normal' transit patients was there some excretion of the activity during the course of the second day, otherwise there was no difference in the images taken in the course of a day (second or third day). A simplified protocol requires a minimum of three images to distinguish all five patterns of colonic transit. The activity should be ingested in the morning (7 00 am) and the first image taken at the end of the working day (8-10 hours after ingestion), the second image on the morning of the second day, and the third image during the course of the third day. This simple protocol would provide all the clinically relevant information necessary for correct classification of the colonic transit. 相似文献
6.
7.
8.
9.
Prednisolone therapy of idiopathic feline lower urinary tract disease: a double-blind clinical study
CA Osborne JM Kruger JP Lulich GR Johnston DJ Polzin LK Ulrich J Sanna 《Canadian Metallurgical Quarterly》1996,26(3):563-569
A double-blind clinical study was performed to evaluate prednisolone as treatment for idiopathic feline lower urinary tract disease. No differences in response were observed in prednisolone- and placebo-treated cats. 相似文献
10.
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