全文获取类型
收费全文 | 1745篇 |
免费 | 21篇 |
专业分类
电工技术 | 2篇 |
化学工业 | 46篇 |
金属工艺 | 4篇 |
机械仪表 | 10篇 |
建筑科学 | 7篇 |
矿业工程 | 1篇 |
能源动力 | 2篇 |
轻工业 | 43篇 |
水利工程 | 3篇 |
石油天然气 | 1篇 |
无线电 | 38篇 |
一般工业技术 | 35篇 |
冶金工业 | 1536篇 |
原子能技术 | 1篇 |
自动化技术 | 37篇 |
出版年
2024年 | 4篇 |
2023年 | 3篇 |
2022年 | 4篇 |
2021年 | 13篇 |
2020年 | 7篇 |
2019年 | 11篇 |
2018年 | 13篇 |
2017年 | 10篇 |
2016年 | 13篇 |
2015年 | 7篇 |
2014年 | 8篇 |
2013年 | 16篇 |
2012年 | 12篇 |
2011年 | 22篇 |
2010年 | 20篇 |
2009年 | 15篇 |
2008年 | 8篇 |
2007年 | 3篇 |
2006年 | 2篇 |
2005年 | 4篇 |
2004年 | 3篇 |
2003年 | 6篇 |
2002年 | 3篇 |
2000年 | 6篇 |
1999年 | 27篇 |
1998年 | 456篇 |
1997年 | 261篇 |
1996年 | 187篇 |
1995年 | 143篇 |
1994年 | 85篇 |
1993年 | 85篇 |
1992年 | 21篇 |
1991年 | 18篇 |
1990年 | 12篇 |
1989年 | 9篇 |
1988年 | 11篇 |
1987年 | 8篇 |
1986年 | 7篇 |
1985年 | 9篇 |
1984年 | 3篇 |
1983年 | 5篇 |
1982年 | 5篇 |
1981年 | 13篇 |
1980年 | 21篇 |
1978年 | 7篇 |
1977年 | 56篇 |
1976年 | 102篇 |
1975年 | 2篇 |
排序方式: 共有1766条查询结果,搜索用时 15 毫秒
161.
H Dosogne AV Capuco MJ Paape E Roets C Burvenich B Fenwick 《Canadian Metallurgical Quarterly》1998,81(3):672-677
Bovine neutrophils contain the enzyme acyloxyacyl hydrolase, which hydrolyzes the acyloxyacyl linkage of the two nonhydroxylated fatty acyl chains to two 3-hydroxy fatty acids in the highly conserved lipid A part of endotoxins with high specificity. This hydrolysis decreases the toxicity of lipid A, but the immunostimulatory capacity of endotoxins is largely maintained. In two trials, we studied the activity of acyloxyacyl hydrolase in neutrophils that had been isolated from the blood of 18 dairy cows around parturition. Between 10 and 26 d after parturition, the activity of acyloxyacyl hydrolase in neutrophils decreased approximately 20% below prepartum activity. At about 2 mo after parturition, acyloxyacyl hydrolase activity returned to prepartum values. Changes in acyloxyacyl hydrolase activity could not be attributed to changes in binding of lipopolysaccharides by the CD14 molecules on neutrophils or monocytes. We hypothesize that decreased acyloxyacyl hydrolase activity in neutrophils shortly after parturition is a factor that increases the susceptibility of dairy cows to coliform mastitis during early lactation. 相似文献
162.
163.
164.
AV Gasparian KK Laktionov MS Belialova NA Pirogova AG Tatosyan IB Zborovskaya 《Canadian Metallurgical Quarterly》1998,77(10):1604-1611
The mapping of allelic loss on the short arm of chromosome 1 has been performed in non-small-cell lung cancer. We used a set of 11 microsatellite loci spanning 1p to examine the frequency of allelic imbalance in a panel of 58 tumours. Fifty-one of 58 (87.9%) cases have shown somatic allelic loss at one or more loci tested. The two shortest regions of the overlap (SRO) of the deletions have been identified: SRO 1 at 1p13.1 and SRO 2 at 1p32-pter. Allelic losses at these regions have been compared among adenocarcinoma and squamous cell carcinoma and no difference has been found. In contrast to SRO 1, deletions at SRO 2 significantly correlated with advanced stage of the disease as well as post-operative metastasizing and relapse. These data may suggest that SRO 1 and SRO 2 can harbour tumour-supressor genes (TSGs) involved in different stages of NSCLC development. SRO 2 is still quite large and its refined mapping should help attempts to clone and identify the putative TSG(s). Microsatellite instability (replication errors) affecting only 6 (10.3%) of 58 tumour samples is an infrequent genetic alteration at the loci tested. 相似文献
165.
166.
AV Sidorov VV Zverev AG Zdanovski? AV Pugach VV Maliushova OG Andzhaparidze 《Canadian Metallurgical Quarterly》1994,39(1):6-10
Lack of uniformity in the classification of oral diseases, and variability of study designs, measurements, methods, and statistical formats, hamper the interpretation, comparison and review of the evidence linking smoking and oral diseases. However, there have been a significant number of controlled studies, allowing definitive conclusions to be drawn. This review of 22 controlled scientific studies from 1983-1992, considers the role of smoking as an aetiological agent in: gingival problems (impaired gingival bleeding, ANUG), periodontal problems (periodontitis, bone loss, tooth loss), and caries. 相似文献
167.
168.
169.
JE Biaglow CJ Koch SW Tuttle Y Manevich IS Ayene EJ Bernhard WG McKenna AV Kachur 《Canadian Metallurgical Quarterly》1998,42(4):769-773
PURPOSE: Methylene blue (MB) can be used as an intracellular electron acceptor. The purpose of this study was to demonstrate the usefulness of MB for the determination of total bioreductive capacity of cell suspensions. METHODS AND MATERIALS: We measured oxygen consumption by Clark electrode and pentose cycle activity by release of 14CO2 from 1-14C-glucose. RESULTS: Methylene blue catalyzes the reaction of intracellular reductants NADPH, NADH, and reduced glutathione (GSH) with oxygen, causing the production of hydrogen peroxide. The reaction rate correlates with the negative charge of molecule (NADPH(-4) > NADH(-2) > GSH(-1)), suggesting that reaction with positively charged oxidized MB is the limiting step of the reaction. In a cellular system MB causes the electron flow from cellular endogenous substrates to oxygen. It is activated by the disruption of the NADP+/NADPH ratio due to several processes. These are direct oxidation of NADPH and GSH, the GSH peroxidase catalyzed reaction of GSH with H2O2, followed by NADPH oxidation by oxidized glutathione (GSSG). This results in increased cellular oxygen consumption and stimulation of the oxidative limb of pentose cycle (PC) in the presence of MB. The cellular effect of MB differs from other electron accepting drugs. Diamide and tert-butylhydroperoxide act as direct oxidants, while MB is an electron carrier to oxygen. Accordingly, MB shows the highest effect on PC activation and oxygen consumption. CONCLUSIONS: Our results indicate that MB may be used for the determination of the total bioreductive capacity of the cells, measured by oxygen consumption and PC activation. 相似文献
170.