全文获取类型
收费全文 | 177篇 |
免费 | 5篇 |
专业分类
电工技术 | 1篇 |
综合类 | 1篇 |
化学工业 | 6篇 |
机械仪表 | 4篇 |
建筑科学 | 6篇 |
能源动力 | 4篇 |
轻工业 | 35篇 |
无线电 | 5篇 |
一般工业技术 | 19篇 |
冶金工业 | 76篇 |
原子能技术 | 1篇 |
自动化技术 | 24篇 |
出版年
2022年 | 1篇 |
2021年 | 1篇 |
2020年 | 5篇 |
2019年 | 1篇 |
2018年 | 2篇 |
2017年 | 1篇 |
2016年 | 4篇 |
2015年 | 4篇 |
2014年 | 2篇 |
2013年 | 30篇 |
2012年 | 2篇 |
2011年 | 1篇 |
2010年 | 5篇 |
2009年 | 6篇 |
2008年 | 1篇 |
2007年 | 1篇 |
2004年 | 3篇 |
2003年 | 2篇 |
2002年 | 1篇 |
2000年 | 2篇 |
1999年 | 4篇 |
1998年 | 21篇 |
1997年 | 9篇 |
1996年 | 7篇 |
1995年 | 4篇 |
1994年 | 7篇 |
1993年 | 5篇 |
1992年 | 4篇 |
1991年 | 2篇 |
1990年 | 1篇 |
1989年 | 3篇 |
1988年 | 1篇 |
1986年 | 1篇 |
1984年 | 5篇 |
1982年 | 2篇 |
1981年 | 2篇 |
1980年 | 1篇 |
1979年 | 3篇 |
1978年 | 1篇 |
1977年 | 2篇 |
1976年 | 9篇 |
1975年 | 6篇 |
1974年 | 1篇 |
1973年 | 2篇 |
1965年 | 1篇 |
1964年 | 1篇 |
1961年 | 1篇 |
1929年 | 1篇 |
排序方式: 共有182条查询结果,搜索用时 15 毫秒
1.
M Nimtz W Martin V Wray KD Kl?ppel J Augustin HS Conradt 《Canadian Metallurgical Quarterly》1993,213(1):39-56
The native structures of the Asn-linked oligosaccharides and the O-glycans at Ser126 of human erythropoietin expressed from recombinant BHK cells have been elucidated. Enzymatically released N-glycans were studied by methylation analyses, fast-atom-bombardment mass spectrometry as well as one- and two-dimensional 1H-NMR spectrometry at 600 MHz. Many (82.7%) were found to be tetraantennary N-acetyllactosamine-type (22.8% with one, 3.6% with two and 0.4% with three N-acetyllactosamine repeats) being tetrasialylated (41%), trisialylated (29.6%) and disialylated (12.2%). A few (9.7%; 4.1% 2,4-branched, 5.6%, 2,6-branched) of the chains were triantennary (5.4% trisialyl, 4.3% disialyl) and 4.6% were of the disialyl diantennary type. Almost all of the innermost GlcNAc residues were alpha 1-6 fucosylated and NeuAc was exclusively alpha 2-3 linked to Gal beta 1-4GlcNAc-R; 60% of the protein was found to be O-glycosylated at Ser126; structures were monosialylated (70%) or disialylated (30%) forms of the Gal beta 1-3GalNAc core type. Glycosylation patterns at individual Asn-Xaa-Thr/Ser sites were determined by analytical high-pH anion-exchange chromatography with pulsed amperometric detection. Only tetraantennary chains with 0-3 N-acetyllactosamine repeats were detected at Asn38 and Asn83, while almost all of the di- and triantennary oligosaccharides were attached to Asn24. Batch analysis of different preparations of recombinant erythropoietin revealed the high reproducibility of the production procedure. Structures containing terminal GalNAc-GlcNAc were detected in small amounts in a few batches. 相似文献
2.
3.
A Further Comparison of Splitting Rules for Decision-Tree Induction 总被引:10,自引:0,他引:10
One approach to learning classification rules from examples is to build decision trees. A review and comparison paper by Mingers (Mingers, 1989) looked at the first stage of tree building, which uses a splitting rule to grow trees with a greedy recursive partitioning algorithm. That paper considered a number of different measures and experimentally examined their behavior on four domains. The main conclusion was that a random splitting rule does not significantly decrease classificational accuracy. This note suggests an alternative experimental method and presents additional results on further domains. Our results indicate that random splitting leads to increased error. These results are at variance with those presented by Mingers. 相似文献
4.
Science China Technological Sciences - We use 9 years data of Cluster to study the dependencies of plasma parameters and energy transport in the plasma sheet on the lasting time of... 相似文献
5.
6.
7.
The significance of guard-cam impact with respect to needle damage is briefly discussed, and a simplified theoretical analysis of guard-cam impact is derived. 相似文献
8.
K. Brad Wray 《Scientometrics》2009,81(3):757-764
I examine whether the professionalization of science, a process that unfolded between 1600 and 1899, afforded better opportunities
for young scientists to make significant discoveries. My analysis suggests that the professionalization of the sciences did
make it a little easier for scientists to make significant contributions at a younger age. But, I also argue that it is easy
to exaggerate the effects of professionalization. Older and middle age scientists continued to play an important role in making
significant discoveries throughout the history of modern science. 相似文献
9.
A simplified mathematical analysis is made of the motion of the latch as the needle passes down the stitch cam. Two practical cases are considered: (i) when the latch retains contact with the previously formed loop of yarn as it rises towards the needle head; and (ii) when the yarn moves with a stick–slip motion such that the latch loses contact with the yarn. It is shown that among possible methods for reducing latch impact are a reduction in latch mass, a reduction in the stitch-cam angle during the period when the latch is closed, and a reduction in the latch length; an improved latch design is also suggested. 相似文献
10.
In previous work, we showed a robust gamma-aminobutyric acid (GABAergic) synaptic input onto embryonic luteinizing hormone-releasing hormone (LHRH) neurons maintained in olfactory explants. In this study, we identify GABAergic neurons in olfactory pit (OP) of embryonic mice in vivo and study, using patch-pipet whole-cell current and voltage clamp techniques, synaptic interactions of these neurons in explant cultures. In vivo, glutamate decarboxylase (GAD, the enzyme which synthesizes GABA) mRNA was first detected in nasal regions on Embryonic Day (E) 11.5. From E12.5 to E13.5, robust GAD expression was localized to cells primarily in the ventral aspect of the OP. GAD mRNA was not detected over dorsally located cells in olfactory sensory or respiratory epithelium. In addition, GAD mRNA was not observed in cells along olfactory axons. GAD mRNA was dramatically reduced in the OP/vomeronasal organ by E16.5. Using antibodies against both GABA and GAD, immunopositive axonal-like tracts were detected in the nasal septum on E12.5. GABAergic staining decreased by E13.5. To examine synaptic interactions of these GABAergic cells, embryonic olfactory explants were generated and maintained in serum-free media. As explants spread, neuron-like cells migrated into the periphery, sometimes forming ganglion-like clusters. Cells were recorded, marked intracellularly with Lucifer Yellow and post-fixation, immunocytochemically examined. Forty-six cells, typically multipolar, were GABAergic, had resting potentials around -50 mV, and exhibited spontaneous action potentials which were generated by spontaneous depolarizing GABAergic (GABAA) synaptic activity. OP neurons depolarized in response to GABA by increasing Cl- conductance. The biophysical properties of OP-derived GABAergic neurons were distinct from those reported for olfactory receptor neurons but similar to embryonic LHRH neurons. However, unlike LHRH neurons, GABAergic neurons did not migrate large distances in olfactory explants or appear to leave the olfactory pit in vivo. 相似文献