全文获取类型
收费全文 | 464篇 |
免费 | 16篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 10篇 |
综合类 | 1篇 |
化学工业 | 47篇 |
金属工艺 | 3篇 |
机械仪表 | 5篇 |
建筑科学 | 15篇 |
能源动力 | 15篇 |
轻工业 | 54篇 |
水利工程 | 4篇 |
石油天然气 | 3篇 |
无线电 | 28篇 |
一般工业技术 | 115篇 |
冶金工业 | 145篇 |
原子能技术 | 6篇 |
自动化技术 | 30篇 |
出版年
2024年 | 1篇 |
2023年 | 1篇 |
2022年 | 5篇 |
2021年 | 2篇 |
2020年 | 2篇 |
2019年 | 1篇 |
2018年 | 5篇 |
2017年 | 12篇 |
2016年 | 6篇 |
2015年 | 4篇 |
2014年 | 9篇 |
2013年 | 14篇 |
2012年 | 17篇 |
2011年 | 25篇 |
2010年 | 26篇 |
2009年 | 17篇 |
2008年 | 29篇 |
2007年 | 17篇 |
2006年 | 22篇 |
2005年 | 10篇 |
2004年 | 18篇 |
2003年 | 3篇 |
2002年 | 7篇 |
2001年 | 11篇 |
2000年 | 11篇 |
1999年 | 9篇 |
1998年 | 38篇 |
1997年 | 28篇 |
1996年 | 20篇 |
1995年 | 13篇 |
1994年 | 21篇 |
1993年 | 15篇 |
1992年 | 8篇 |
1991年 | 8篇 |
1990年 | 6篇 |
1989年 | 5篇 |
1988年 | 5篇 |
1987年 | 4篇 |
1986年 | 2篇 |
1985年 | 1篇 |
1983年 | 1篇 |
1981年 | 2篇 |
1979年 | 2篇 |
1978年 | 1篇 |
1977年 | 3篇 |
1976年 | 12篇 |
1975年 | 1篇 |
1967年 | 1篇 |
排序方式: 共有481条查询结果,搜索用时 0 毫秒
71.
Zahari Zlatev Per Grove Thomsen 《International journal for numerical methods in engineering》1979,14(7):1051-1061
The application of finite element methods to parabolic partial differential equations leads to large linear systems of first-order ordinary differential equations. Very often these systems are stiff and difficulties arise in their numerical solution. We attempt to analyse the problem of how to select numerical methods for the solution of such linear systems. 相似文献
72.
J L Thomsen 《Journal of dairy science》1976,59(2):288-292
Magnesium, potassium, sodium, creatinine and bilirubin concentrations, and osmolality in bovine fetal fluids have been investigated to seek a possible application to the determination of gestation age. Potassium ion concentration during pregnancy decreased in amniotic fluid. Sodium ion concentration and osmolality increased in allantoic fluid during the same period. Creatinine concentration rose throughout pregnancy in both amniotic and allantoic fluids. However, none of these indicators provided a reliable correlation with fetal age as determined by measurements of head circumference. 相似文献
73.
L. Sennerby P. Thomsen L. E. Ericson 《Journal of materials science. Materials in medicine》1993,4(3):240-250
The tissue response to screw-shaped implants of commercially pure titanium was studied by light microscopy 3–180 days after insertion in the rabbit tibia. The implant site in the tibial metaphysis consisted mainly of cortical bone. Three days after implantation, osteoblasts, producing osteoid, were observed at the endosteal surface and elongated mesenchymal cells were present in the injury area. Some macrophages but rather few other inflammatory cells were identified. Multinuclear giant cells were in direct contact with the implant and formed an almost continuous layer along the surface from the 7th day. The number of giant cells decreased with time and with increased bone-titanium contact. Bone formation was never seen direct on the implant surface but was first observed at day 7 as a woven trabecular bone formed at the endosteal surface and extending towards the implant and as a solitary formation of woven bone close to the implant. The solitary bone matrix served as a base for surface osteoblasts which produced osteoid in a lamellar arrangement. With time the two types of newly formed bone fused and more bone filled the threads and became remodelled by bone remodelling units. Light microscopic morphometry in ground sections demonstrated that the bone/titanium contact and bone area in the threads increased with time up to 6 months after implantation 相似文献
74.
JC Nielsen HR Andersen PE Thomsen L Thuesen PT Mortensen T Vesterlund AK Pedersen 《Canadian Metallurgical Quarterly》1998,97(10):987-995
OBJECTIVE: In the present study, physical and sexual abuse among incarcerated youth were examined with respect to sexual activity, contraceptive use, and pregnancy. METHOD: The self-report survey data were collected from 62 females and 334 males who were incarcerated in Nevada youth correctional facilities in the summer of 1994. Of the males, 46.8% (n = 156) reported a history of physical abuse and 9.9% (n = 33) reported sexual abuse. A surprisingly high 73% (n = 46) of the females reported a history of physical abuse and 68.3% (n = 43) reported sexual abuse. RESULTS: The analyses indicated that females who reported a history of sexual abuse had an earlier mean age of first intercourse than those who reported no sexual abuse. In addition, male and female respondents with a history of physical and/or sexual abuse reported using no method of contraception as compared to youth with no history of abuse. CONCLUSIONS: Implications of these results for detention-based counseling and prevention programming are discussed. 相似文献
75.
76.
77.
PH Thomsen 《Canadian Metallurgical Quarterly》1996,158(34):4737-4740
Obsessive-compulsive disorder (OCD) in children and adolescents is apparently a much more common disorder than previously believed. The literature on OCD in children and adolescents is reviewed, and OCD is described as a severe disorder with a poor prognosis for about half of the patients. The clinical picture seems to be the same across different cultures. The most common symptoms are obsessions about dirt and contamination and washing rituals. 相似文献
78.
PURPOSE: The purpose was to obtain normal values of the apparent diffusion coefficient (ADC) in the infant brain and to compare ADC maps with T1- and T2-weighted images. METHOD: Diffusion was measured in nine infants with an ECG-gated SE sequence compensated for first-order motion. One axial slice at the basal ganglia level was investigated with the diffusion-encoding gradients in the slice-selection direction. RESULTS: On ADC maps, the corpus callosum and the optic radiations appeared dark before the onset of myelination, and the crus posterior of the internal capsule could be visualized before it appeared on T1- or T2-weighted images. In gray and white matter, the mean ADC ranged from 0.95 x 10(-9) to 1.76 x 10(-9) m2/s. In the frontal and occipital white matter, in the genu corporis callosi, and in the lentiform nucleus, the ADC decreased with increasing age. The cortex/white matter ratio of the ADC increased with age and approached 1 at the age of 30 weeks. CONCLUSION: ADC maps add information to the T1 and T2 images about the size and course of unmyelinated as well as myelinated tracts in the immature brain. 相似文献
79.
80.
E Soloy V Srsen A Pavlok P Hyttel PD Thomsen SD Smith R Procházka M Kubelka R H?ier P Booth J Motlík T Greve 《Canadian Metallurgical Quarterly》1997,111(1):151-157
It was demonstrated previously that replication of plasmids derived from bacteriophage lambda (so-called lambda plasmids) is inhibited in wild-type Escherichia coli cells starved for isoleucine and arginine whereas it proceeds under the same conditions in relA mutants. Since replication of other replicons during the stringent or relaxed response depends on the nature of the deprived amino acid, we investigated replication of lambda plasmids in E. coli relA+ and relA- strains starved for different amino acids. We found that replication of lambda plasmids is generally inhibited during the stringent, but not relaxed, response. Differences between cells starved for different amino acids, although reproducible, were not dramatic. Amino acid starvation was previously proposed as a method for amplification of lambda plasmid DNA in vivo. We found that during amino acid limitation lambda plasmids replicate more extensively in the relA mutants than during amino acid starvation. The efficiency of plasmid DNA amplification was found to be dependent on the kind of limited amino acid; in relA- bacteria limited for leucine we observed about 10-fold plasmid amplification. Some lambda plasmid replication was also found under these conditions in the relA+ host. The mechanism of the stringent control of lambda plasmid DNA replication has already been proposed. Here the possible mechanism of the regulation of lambda plasmid replication during amino acid limitation is presented. 相似文献