全文获取类型
收费全文 | 537篇 |
免费 | 2篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 1篇 |
化学工业 | 17篇 |
金属工艺 | 4篇 |
机械仪表 | 4篇 |
建筑科学 | 15篇 |
能源动力 | 5篇 |
轻工业 | 17篇 |
无线电 | 44篇 |
一般工业技术 | 22篇 |
冶金工业 | 386篇 |
原子能技术 | 3篇 |
自动化技术 | 22篇 |
出版年
2020年 | 2篇 |
2018年 | 1篇 |
2017年 | 3篇 |
2016年 | 2篇 |
2014年 | 3篇 |
2013年 | 14篇 |
2012年 | 9篇 |
2011年 | 7篇 |
2010年 | 4篇 |
2009年 | 3篇 |
2008年 | 6篇 |
2007年 | 7篇 |
2006年 | 3篇 |
2005年 | 3篇 |
2004年 | 5篇 |
2003年 | 5篇 |
2002年 | 4篇 |
2001年 | 5篇 |
2000年 | 5篇 |
1999年 | 13篇 |
1998年 | 131篇 |
1997年 | 72篇 |
1996年 | 57篇 |
1995年 | 36篇 |
1994年 | 16篇 |
1993年 | 29篇 |
1992年 | 7篇 |
1991年 | 6篇 |
1990年 | 3篇 |
1989年 | 5篇 |
1988年 | 2篇 |
1987年 | 5篇 |
1986年 | 1篇 |
1985年 | 5篇 |
1984年 | 2篇 |
1983年 | 6篇 |
1982年 | 4篇 |
1981年 | 3篇 |
1980年 | 6篇 |
1978年 | 1篇 |
1977年 | 17篇 |
1976年 | 16篇 |
1975年 | 2篇 |
1974年 | 2篇 |
1972年 | 1篇 |
1964年 | 1篇 |
排序方式: 共有540条查询结果,搜索用时 0 毫秒
71.
72.
In DFB (distributed feedback) lasers, the shape of the longitudinal intensity and carrier density distributions changes above threshold as a result of spatial hole burning. The longitudinally distributed coupling of spontaneous emission into the lasing mode also plays an important role for the noise properties. The authors demonstrate how both effects can be included in a dynamic analysis. They extend their previously developed theory for multielectrode lasers to enable calculation of stability properties as well as small-signal modulation responses and noise spectra. The theory is used to study global and local stability of the stationary solutions (modes). The numerical results for several laser structures are presented. It is shown that symmetric DFB lasers are likely to exhibit pitchfork bifurcations in their static tuning characteristics as the current is increased. The authors discuss how the presence or proximity of such instabilities can affect the modulation and noise properties, and in particular, the spectral linewidth 相似文献
73.
NN Petrovichev OV Chistiakova AV Smirnov TD Rudinskaia VS Poltoranina 《Canadian Metallurgical Quarterly》1995,57(4):25-30
Anti-macrophage monoclonal antibody (Mab) D-11 was tested in surgical material and biopsies of non-epithelial tumors and tumor-like lesions from 181 patients in order to assess possibility of using this Mab for diagnosis of histiocytic tumors, malignant fibrous histiocytoma in particular. The study was performed in parallel on cryostat sections and smears by immuno-peroxidase method. It is established that D-11 reacts positively with both histiocytic tumors and tumors of other genesis this being a limiting factor in differential diagnosis of histiocytic tumors. However, taking into consideration 100% of positive results with histiocytic tumors only, this antibody can be used for exclusion of tumors studied from the group of histiocytomas in cases of negative reaction. 相似文献
74.
75.
76.
77.
DC James RB Freedman M Hoare OW Ogonah BC Rooney OA Larionov VN Dobrovolsky OV Lagutin N Jenkins 《Canadian Metallurgical Quarterly》1995,13(6):592-596
Recombinant human interferon-gamma (IFN-gamma) was expressed in Chinese hamster ovary cells, baculovirus-infected Sf9 insect cells and the mammary gland of transgenic mice. The N-linked carbohydrate populations associated with both Asn25 and Asn97 glycosylation sites were characterized by matrix-assisted laser desorption/ionization-mass spectrometry (MALDI-MS) in combination with exoglycosidase array sequencing. A site-specific analysis of dual (2N) and single (1N) site-occupancy variants of IFN-gamma derived from Chinese hamster ovary cells showed that N-glycans were predominantly of the complex bi- and triantennary type. Although Asn25-linked glycans were substituted with a core fucose residue, Asn97 N-glycans were predominantly non-fucosylated, and truncated complex and high-mannose oligosaccharide chains were also evident. Transgenic mouse derived IFN-gamma exhibited considerable site-specific variation in N-glycan structures. Asn25-linked carbohydrates were of the complex, core fucosylated type, Asn97-linked carbohydrates were mainly of the oligomannose type, with smaller proportions of hybrid and complex N-glycans. Carbohydrates associated with both glycosylation sites of IFN-gamma from Sf9 insect cells were mainly tri-mannosyl core structures, with fucosylation confined to the Asn25 site. These data demonstrate the profound influence of host cell type and protein structure on the N-glycosylation of recombinant proteins. 相似文献
78.
DM Izmaylov LK Obukhova OV Okladnova AP Akifyev 《Canadian Metallurgical Quarterly》1993,28(2):169-180
The dynamics of life span (LS) and fecundity in Drosophila melanogaster, strain D-32, were analyzed in a series of successive generations. Highly reliable variations in both fitness components were found. On initial inspection the variations would be characterized as random or irregular wherein mean values differed up to threefold. The variance in longevity is greater in females than in males. By use of mathematical procedures we have shown a scale regularity in LS distributions for all generations. Such regularity, in spite of considerable differences in absolute values (mean and maximum LS), suggested that the origin of LS instability is nonrandom. 相似文献
79.
80.
The device consists of a conventional or a λ/4-shifted DFB (distributed-feedback) laser monolithically integrated with an external waveguide section with separate electrodes for phase control. Tuning curves are presented for threshold current, frequency, linewidth, and output power. The analysis demonstrates a generally higher side mode suppression and larger frequency tuning range but also a larger linewidth for the λ/4-shifted device compared to the device with a conventional DFB section 相似文献