全文获取类型
收费全文 | 2379篇 |
免费 | 5篇 |
国内免费 | 3篇 |
专业分类
综合类 | 1篇 |
化学工业 | 9篇 |
金属工艺 | 3篇 |
能源动力 | 1篇 |
轻工业 | 1篇 |
无线电 | 4篇 |
一般工业技术 | 39篇 |
冶金工业 | 2324篇 |
自动化技术 | 5篇 |
出版年
2019年 | 4篇 |
2017年 | 1篇 |
2016年 | 1篇 |
2015年 | 3篇 |
2014年 | 1篇 |
2013年 | 2篇 |
2012年 | 7篇 |
2011年 | 7篇 |
2010年 | 4篇 |
2009年 | 3篇 |
2008年 | 2篇 |
2007年 | 3篇 |
2006年 | 1篇 |
2005年 | 2篇 |
2004年 | 4篇 |
2003年 | 6篇 |
2002年 | 3篇 |
2001年 | 3篇 |
2000年 | 1篇 |
1999年 | 84篇 |
1998年 | 728篇 |
1997年 | 447篇 |
1996年 | 271篇 |
1995年 | 156篇 |
1994年 | 113篇 |
1993年 | 158篇 |
1992年 | 21篇 |
1991年 | 17篇 |
1990年 | 25篇 |
1989年 | 18篇 |
1988年 | 15篇 |
1987年 | 18篇 |
1986年 | 20篇 |
1985年 | 12篇 |
1983年 | 3篇 |
1982年 | 12篇 |
1981年 | 11篇 |
1980年 | 21篇 |
1979年 | 1篇 |
1978年 | 5篇 |
1977年 | 53篇 |
1976年 | 115篇 |
1975年 | 1篇 |
1955年 | 4篇 |
排序方式: 共有2387条查询结果,搜索用时 15 毫秒
991.
992.
S Favilli L De Simone I Pollini MG Bettuzzi D Cianfrini R Crepaz V Santillo D Trevisanuto G Vignati A Manetti 《Canadian Metallurgical Quarterly》1998,28(11):1247-1252
Modifying bacterial virulence genes to probe the nature of host immunity is mostly unexplored. Here we investigate whether host immune responses can be regulated by modification of bacterial virulence genes. In mice, attenuated Salmonella mutant strains with clinical relevance elicited differential host immune responses. Oral administration of a mutant strain with a PhoP-null phenotype promoted potent innate immune responses of macrophages that were sufficient for host defense. In contrast, administration of an Aro- mutant strain elicited stronger specific antibody and T-helper (Th)-cell responses, wherein Th1-type cells were required for clearance. Thus, genetic manipulation of bacteria may be used to broadly alter immune mechanisms that regulate attenuation within the host and to tailor host immunity to specific bacterial pathogens. 相似文献
993.
994.
995.
Discusses the role of testing in (a) delineating the behavioral consequences of brain lesions and (b) predicting the likely impact of such ability deficits on everyday functioning. The available studies that relate neuropsychological test scores to aspects of self-care and independent living, academic achievement, and vocational functioning are reviewed. Results are generally positive, but the clinical value of these studies is limited by the fact that most used only intelligence or screening tests with S groups that were not very representative of the patient population referred for neuropsychological testing. Methodological considerations for future research are discussed, in addition to the potential advantages of clinical over actuarial prediction in this area. To illustrate this type of clinical interpretation and suggest hypotheses for future research, it is described how results on comprehensive neuropsychological testing can be considered in relation to questions about patients' everyday functioning. (50 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
996.
997.
JR Sowers JM Hershman HE Carlson AE Pekary AW Reed MG Nair CM Baugh 《Canadian Metallurgical Quarterly》1976,43(4):856-860
The synthetic N3im-methyl analogue of thyrotropin releasing hormone (methyl-TRH) was administered intravenously to 15 euthyroid men, ages 36-62, in graded doses from 6.25 mug to 500 mug in order to establish the range of response of prolactin (PRL), TSH, T3 and T4 to various doses of methyl-TRH. There was a dose-related rise in serum TSH, PRL, T3, and T4 which gave a nearly linear relationship when the integrated area of response was used as an index of response to the various doses of methyl-TRH. All 15 men had a clear elevation in TSH, PRL, T3 and T4 following the lowest dose of methyl-TRH TESTED (6.25 mug). There was considerable variability in the response to methyl-TRH among the individuals. One hundred mug of methyl-TRH gave a maximum TSH response; a 25 mug dose elicited a maximum PRL response. 相似文献
998.
TW van der Mark R Peset H Beekhuis A Kiers AE Rookmaker MG Woldring 《Canadian Metallurgical Quarterly》1980,21(11):1029-1034
A method is described for analysis of xenon-133 washin and washout curves, in the presence of a slowly varying background. The method uses least-squares fitting of a single exponential together with a quadratic function to correct for the background. The method has been applied both to simulated data and to data from 25 patients. The accuracy in the relevant lung parameters was 5% over a wide range of the specific ventilation. A comparison is made with other methods in use to measure regional lung-function parameters. Our method produces reliable results even when specific ventilation is low, which can occur in patients with chronic airflow obstruction, where other methods may incur errors of more than 45%. 相似文献
999.
DP O'Brart DS Gartry CP Lohmann AL Patmore MG Kerr Muir J Marshall 《Canadian Metallurgical Quarterly》1993,77(11):702-708
A series of 122 eyes with band keratopathy was treated by excimer laser phototherapeutic keratectomy (PTK), with a mean follow up of over 12.3 months (range 3 to 60 months). A single photoablation zone was used to remove the opacity over the visual axis in smooth surfaced band deposition. In eyes with reduced vision, an improvement was reported in 88% and in a series of 66 eyes mean Snellen visual acuity increased significantly (p < 0.05, t = 2.27). A reduction in glare was reported in 88% and in a series of 17 patients, visual contrast sensitivity (p < 0.01) and measurements of disability glare (p < 0.01) improved postoperatively. The mean hyperopic shift in 32 eyes at 6 months was 1.4 D (range 0-4.25 D). Multiple overlapping ablation zones, with mechanical debulking of large calcium plaques, were used to smooth the irregular corneal surface in eyes with rough bands. Ocular discomfort was improved in 95%. Band keratopathy recurred in nine eyes (8%) within 2 to 30 months (mean 12 months) of surgery, with silicone oil responsible in five eyes. Reablation was necessary in three eyes and performed successfully in all cases. Excimer laser PTK is a safe and effective outpatient treatment for band keratopathy. 相似文献
1000.
MG Otsyula CJ Miller AF Tarantal ML Marthas TP Greene JR Collins KK van Rompay MB McChesney 《Canadian Metallurgical Quarterly》1996,222(1):275-278
We have reported that infection of fetal or neonatal rhesus macaques with attenuated SIVmac1A11 results in transient viremia, anti-SIV antibody responses, weak or absent cytotoxic T-lymphocyte responses, and no clinical disease. In light of these results, we hypothesized that congenital infection with SIVmac1A11 produced immune tolerance to SIV. To test this hypothesis, at approximately 1 year of age, five rhesus macaques infected with SIVmac1A11 as fetuses (n = 3) or newborns (n = 2) and five naive juvenile rhesus macaques were challenged orally with pathogenic SIVmac251. The five naive animals became persistently viremic after oral SIVmac251 inoculation. In contrast, one of three monkeys inoculated with SIVmac1A11 in utero and one of two animals inoculated with SIVmac1A11 at birth were virus culture negative. Virus was isolated from PBMC of the other animals infected with SIVmac1A11 in utero or at birth. However, one animal had a substantially lower viral load than the control animals. These results suggest that SIV-specific immunity rather than tolerance results from congenital infection with attenuated SIVmac and that this immunity is sufficient to provide some protection from pathogenic virus challenge. These results also demonstrate that SIV can be transmitted orally in 6- to 17-month-old rhesus monkeys. 相似文献