全文获取类型
收费全文 | 953篇 |
免费 | 11篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 1篇 |
综合类 | 4篇 |
化学工业 | 72篇 |
金属工艺 | 45篇 |
机械仪表 | 8篇 |
建筑科学 | 8篇 |
轻工业 | 26篇 |
水利工程 | 3篇 |
无线电 | 18篇 |
一般工业技术 | 41篇 |
冶金工业 | 693篇 |
自动化技术 | 46篇 |
出版年
2023年 | 1篇 |
2022年 | 1篇 |
2021年 | 1篇 |
2020年 | 3篇 |
2019年 | 3篇 |
2018年 | 4篇 |
2017年 | 8篇 |
2016年 | 20篇 |
2015年 | 10篇 |
2014年 | 12篇 |
2013年 | 24篇 |
2012年 | 9篇 |
2011年 | 38篇 |
2010年 | 15篇 |
2009年 | 23篇 |
2008年 | 12篇 |
2007年 | 12篇 |
2006年 | 9篇 |
2005年 | 13篇 |
2004年 | 11篇 |
2003年 | 4篇 |
2002年 | 8篇 |
2001年 | 8篇 |
2000年 | 3篇 |
1999年 | 34篇 |
1998年 | 225篇 |
1997年 | 131篇 |
1996年 | 92篇 |
1995年 | 28篇 |
1994年 | 46篇 |
1993年 | 26篇 |
1992年 | 6篇 |
1991年 | 9篇 |
1990年 | 7篇 |
1989年 | 4篇 |
1988年 | 7篇 |
1987年 | 9篇 |
1986年 | 12篇 |
1985年 | 5篇 |
1984年 | 1篇 |
1982年 | 2篇 |
1981年 | 3篇 |
1980年 | 11篇 |
1977年 | 16篇 |
1976年 | 35篇 |
1975年 | 2篇 |
1972年 | 1篇 |
1955年 | 1篇 |
排序方式: 共有965条查询结果,搜索用时 0 毫秒
31.
32.
TM Link S Majumdar P Augat JC Lin D Newitt Y Lu NE Lane HK Genant 《Canadian Metallurgical Quarterly》1998,13(7):1175-1182
The purpose of this study was to use high resolution (HR) magnetic resonance (MR) images of the calcaneus to investigate the trabecular structure of patients with and without osteoporotic hip fractures and to compare these techniques with bone mineral density (BMD) in differentiating fracture and nonfracture patients. Axial and sagittal HR MR images of the calcaneus were obtained in 50 female (23 postmenopausal patients with osteoporotic hip fractures and 27 postmenopausal controls). A three-dimensional gradient-echo sequence was used with a slice thickness of 500 micron and in plane resolution of 195 x 195 micron. Texture analysis was performed using morphological features, analogous to standard histomorphometry and fractal dimension. Additionally, BMd measurements of the hip (dual-energy X-ray absorptiometry) were obtained in all patients. Significant differences between both patient groups were obtained using morphological parameters and fractal dimension as well as hip BMD (p < 0.05). Odds ratios for the texture parameters apparent (app.) bone volume/total volume and app. trabecular separation were higher than for hip BMD. Receiver operator characteristic values of texture measures and hip BMD were comparable. In conclusion, trabecular structure measures derived from HR MR images of the calcaneus can differentiate between postmenopausal women with and without osteoporotic hip fractures. 相似文献
33.
We have examined the immunolocalization of beta 1-integrin during feather development in the spino-lumbar tract of the backskin from normal and scaleless chick embryos. beta 1-integrin appears during early feather development in three distinct phases which correspond to important developmental events. The first phase (5-5 1/2 days of incubation; Hamburger and Hamilton [H.H.] stage 27) represents the period prior to the formation of dermis. During this phase, beta 1-integrin antiserum labels mesenchymal cells located in the central region of the spino-lumbar tract where the initiation site for feather development is located. The second phase (5 1/2-7 1/2 days of incubation; H.H. stages 28-32) corresponds to the period during which dermis is formed. The cells that make up the dermis are readily distinguished by their lack of beta 1-integrin immunostaining. The third phase (7 1/2-10 days of incubation; H.H. stages 33-36) begins with the sudden appearance of beta 1-integrin in the central and lateral regions of the dermis. The pattern of beta 1-integrin immunostaining in scaleless backskin becomes different from that of normal backskin during this phase. In normal backskin the dermal condensations of feather germs are not labeled with the beta 1-integrin antiserum. This produces a heterogeneous immunostaining pattern very similar to the pattern seen for Type I collagen (Mauger et al. [1982] Dev. Biol. 94:93-105). In contrast, homogeneous immunostaining is observed in the dermis of scaleless backskin. The initial time of appearance, manner of appearance, and pattern of integrin expression in the third phase suggest that beta 1-integrin may be involved in the stabilization of the feather pattern. We also observed the appearance of beta 1-integrin on the epidermal basal cells during the time of feather follicle formation. The beta 1-integrin antiserum reacts strongly with the baso-lateral surfaces of normal basal cells, yet the basal surfaces of the scaleless basal cells are unstained. This lack of immunostaining along the basal surfaces of the scaleless basal cells may relate to the abnormal adhesion between the epidermis and dermis in scaleless backskin. 相似文献
34.
35.
A theoretical approach to studying work empowerment in nursing: a review of studies testing Kanter's theory of structural power in organizations 总被引:2,自引:0,他引:2
HK Laschinger 《Canadian Metallurgical Quarterly》1996,20(2):25-41
Although work empowerment is a common theme in the current nursing systems literature, few systematic programs of research have studies the phenomenon from an explicitly theoretical framework. The author summarizes the results of a series of studies in a program of research designed to test Rosabeth Moss Kanter's Structural Theory of Organizational Behavior in the nursing population. Future directions for theory and research are proposed. 相似文献
36.
Antinociception produced by microinjection of morphine in the ventrolateral periaqueductal gray is mediated in part by alpha2-adrenoceptors in the spinal cord dorsal horn. However, several recent reports demonstrate that microinjection of morphine in the ventrolateral periaqueductal gray inhibits nociceptive responses to noxious heating of the tail by activating descending neuronal systems that are different from those that inhibit the nociceptive responses to noxious heating of the feet. More specifically, alpha2-adrenoceptors appear to mediate the antinociception produced by morphine using the tail-flick test, but not that using the foot-withdrawal or hot-plate tests. The present study extended these findings and determined the role of alpha1-adrenoceptors in mediating the antinociceptive effects of morphine microinjected into the ventrolateral periaqueductal gray using both the foot-withdrawal and the tail-flick responses to noxious radiant heating in lightly anesthetized rats. Intrathecal injection of selective antagonists was used to determine whether the antinociceptive effects of morphine were modulated by alpha1-adrenoceptors. Injection of the selective alpha1-adrenoceptor antagonists prazosin or WB4101 potentiated the increase in the foot-withdrawal response latency produced by microinjection of morphine in the ventrolateral periaqueductal gray. In contrast, either prazosin or WB4101 partially reversed the increase in the tail-flick response latency produced by morphine. These results indicate that microinjection of morphine in the ventrolateral periaqueductal gray modulates nociceptive responses to noxious heating of the feet by activating descending neuronal systems that are different from those that inhibit the nociceptive responses to noxious heating of the tail. More specifically, alpha1-adrenoceptors mediate a pro-nociceptive action of morphine using the foot-withdrawal response, but in contrast, alpha1-adrenoceptors appear to mediate part of the antinociceptive effect of morphine determined using the tail-flick test. 相似文献
37.
HK Jin T Yamashita K Ochiai O Haller T Watanabe 《Canadian Metallurgical Quarterly》1998,36(9-10):311-322
38.
H Susaki K Suzuki M Ikeda H Yamada HK Watanabe 《Canadian Metallurgical Quarterly》1998,46(10):1530-1537
Arginine-vasopressin (AVP) was acylated with various acyl azides (2a-j) in pH 9.1 buffer to give AVP derivatives (11a-j) modified at the tyrosine side chain with a carbohydrate via a spacer arm. Glycoconjugates of AVP modified at the N-terminal amide (12a-e) were also synthesized from AVP and carboxylic acids (3a-e) using dicyclohexylcarbodiimide and 1-hydroxybenzotriazole as coupling agent. Analogues (11a-j) exhibited greater in vivo antidiuretic activity than AVP. AVP and glycoconjugates (12a-e) were stable in rat plasma. On the other hand, glycoconjugates (11a-i) were found to readily convert to AVP according to first order kinetics. Hence, 11a-j are considered to be prodrugs of AVP. 相似文献
39.
40.