全文获取类型
收费全文 | 544篇 |
免费 | 0篇 |
专业分类
电工技术 | 1篇 |
矿业工程 | 1篇 |
石油天然气 | 1篇 |
无线电 | 1篇 |
一般工业技术 | 1篇 |
冶金工业 | 525篇 |
自动化技术 | 14篇 |
出版年
2023年 | 1篇 |
2012年 | 2篇 |
2011年 | 2篇 |
2003年 | 3篇 |
1999年 | 7篇 |
1998年 | 136篇 |
1997年 | 83篇 |
1996年 | 62篇 |
1995年 | 28篇 |
1994年 | 36篇 |
1993年 | 28篇 |
1992年 | 2篇 |
1991年 | 10篇 |
1990年 | 8篇 |
1989年 | 10篇 |
1988年 | 7篇 |
1987年 | 5篇 |
1986年 | 3篇 |
1985年 | 6篇 |
1984年 | 2篇 |
1983年 | 1篇 |
1982年 | 5篇 |
1981年 | 5篇 |
1980年 | 5篇 |
1979年 | 1篇 |
1978年 | 2篇 |
1977年 | 29篇 |
1976年 | 55篇 |
排序方式: 共有544条查询结果,搜索用时 15 毫秒
151.
LN Turkeri I Daudi JL Abraham AR Wojtowycz GP Haas 《Canadian Metallurgical Quarterly》1998,5(1):96-8; discussion 99
This paper reports a rare case of cirsoid renal arteriovenous malformation (AVM) that showed radiological characteristics of a renal malignancy. Using only conventional procedures such as computerized tomography, the present case was misdiagnosed as a solid tumor mass and therefore radical nephrectomy was indicated. Angiographic analysis is expected to improve the accuracy of diagnosis of AVM, thus reducing the need to resort to invasive techniques. 相似文献
152.
DL Wetzel AJ Eilert LN Pietrzak SS Miller JA Sweat 《Canadian Metallurgical Quarterly》1998,44(1):145-168
Routine use of 6 microm or 12 microm apertures with synchrotron microspectroscopy provide good spectra without excessive co-addition of scans. 100% mapping by stepping in pixel sized increments reveals chemical heterogeneity within cellular dimensions. The brightness of the synchrotron source and the absence of thermal noise compared to a conventional thermal (globar) source yields favorable signal-to-noise operation. The nondivergent characteristics of the source result in minimal loss of radiation at the aperture, hence, spatial resolution approaches the diffraction limit. Details of cellular dimensions are then localized within any maps produced and individual spectra obtained from adjacent pixels clearly shows the striking difference in chemistry even within a microscopic vicinity. In this report the mapping of plant tissue with the synchrotron is contrasted to previous lower spatial resolution mapping experiments done with the globar on similar materials using interpolation between separated sampling spots and larger apertures. 相似文献
153.
The pathogenesis of endodermal cysts of the posterior fossa is still incompletely understood. The authors reviewed three new cases and those reported in the literature to clarify the clinical, pathological, radiological, and surgical characteristics of these lesions. A total of 49 cases were reviewed. Details on demographic profiles, clinical characteristics, histopathological and radiological features, and surgical methods were collected. These cysts have a predominance in male patients (61%) and can occur at any age (birth-77 years). In patients with posterior fossa endodermal cysts there is a bimodal age distribution and headache is the most frequent complaint. On immunohistopathological examination, endodermal cysts were reactive for epithelial membrane antigen and for keratin immunostains whenever the latter were tested. The cysts were reactive for carcinoembryonic antigen in nine of 11 cases. Endodermal cysts were located anterior to the brainstem in 51% of cases and in the fourth ventricle in 21% of cases. They frequently appeared hypodense on computerized tomography scans, and in five cases, the lesion was missed. The cyst's appearance on magnetic resonance imaging is variable. Resection was complete in 19 cases and partial in 11; marsupialization was achieved in two cases. Three recurrences have been reported. Total excision with preservation of neurological function should be the goal. Cranial base approaches are helpful for surgical access in selected examples of these lesions. 相似文献
154.
155.
On most real channels hybrid error control schemes are expected to provide a throughput higher than that of automatic repeatrequest (ARQ) systems and a reliability better than forward error correction (FEC) systems. On compound channels, channels with a mixture of random and burst errors, generalized burst-trapping (GBT) codes seem to be quite effective for FEC. In this paper, a hybrid scheme with Go BackN ARQ as the retransmission component and GBT code as the FEC component, is described. Its performance is analyzed in terms of throughput efficiency and undetected error probability and is compared with that of a forward-acting GBT code. Numerical calculations of the parameters are presented to illustrate the performance. 相似文献
156.
157.
158.
159.
160.