首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   233篇
  免费   9篇
电工技术   16篇
化学工业   59篇
金属工艺   8篇
机械仪表   3篇
建筑科学   2篇
矿业工程   1篇
能源动力   21篇
轻工业   20篇
无线电   18篇
一般工业技术   45篇
冶金工业   38篇
原子能技术   2篇
自动化技术   9篇
  2022年   2篇
  2021年   5篇
  2020年   2篇
  2019年   4篇
  2018年   5篇
  2017年   2篇
  2016年   1篇
  2015年   5篇
  2014年   5篇
  2013年   10篇
  2012年   12篇
  2011年   12篇
  2010年   10篇
  2009年   15篇
  2008年   14篇
  2007年   16篇
  2006年   12篇
  2005年   4篇
  2004年   11篇
  2003年   1篇
  2002年   8篇
  2001年   2篇
  2000年   2篇
  1999年   7篇
  1998年   11篇
  1997年   13篇
  1996年   9篇
  1995年   6篇
  1994年   2篇
  1993年   2篇
  1992年   4篇
  1991年   2篇
  1990年   2篇
  1989年   2篇
  1988年   3篇
  1987年   1篇
  1985年   1篇
  1984年   3篇
  1982年   2篇
  1981年   2篇
  1979年   2篇
  1977年   3篇
  1976年   3篇
  1968年   1篇
  1967年   1篇
排序方式: 共有242条查询结果,搜索用时 62 毫秒
51.
Genetic analysis of diabetogenic genes involved in developing spontaneous diabetes of NIDDM type in the OLETF rat was performed in (OLETF female X B N male)F2 and (OLETF female X BN male)F1 female X OLETF male backcross male offspring. In the F2 and/or backcross offspring, a high frequency of diabetes was found to be associated with a coat color gene, H (hooded). Since it is know that H gene is located on chromosome 14. an attempt was made to examine the linkage association of the gene responsible for elevating plasma glucose with various microsatellite markers of chromosome 14 in male F2 and/or backcross offspring. The results show that a high linkage exists with a microsatellite marker, D14Mit4 (LOD > 2). The gene was designated Odb2. It was also found that both genes, Odb1 which was previously found on chromosome X, and homozygous Odh2 are required to cause elevated plasma glucose in OGTT.  相似文献   
52.
To elucidate the effects of recombinant human erythropoietin (rHuEpo) on the interactions between glomerular endothelial cells (GENs) and mesangial cells (GMCs), we investigated whether or not cultured bovine GENs alter endothelin (ET)-1 secretion from bovine MCs and MC proliferate under basal or rHuEpo-stimulated conditions. Incubation for 24 hours with synthetic ET-1 stimulated MC in a dose-dependent manner. In addition, 100 pg/ml of ET-1 significantly stimulated MC proliferation after more than 12 hours incubation. Moreover, rHuEpo stimulated ET-1 secretion from GENs in a dose-dependent manner and showed less stimulation of ET-1 secretion from GMCs than GENs. DNA synthesis in both GENs and GMCs was significantly stimulated with more than 5 U/ml of rHuEpo. ET-1 secretion from GENs co-cultured with GMCs was higher than that from cultured GENs only. Conditioned medium, obtained from co-culture of GENs and GMCs, stimulated the proliferation of GMCs that were significantly inhibited with 10(-6) M approximately 10(-5) M BQ-123, a ETA receptor antagonist. These results suggest that rHuEpo directly stimulates the proliferation of GENs and GMCs, and this stimulatory effect is in part due to ET-1 secreted from these cells, especially GENs.  相似文献   
53.
The pressure to infiltrate molten aluminum into alumina short-fiber preforms was generated by centrifugal force, and it was proved that centrifugal force is effective as a motive force for the infiltration and sound composites that are produced. The initiation pressure of the infiltration was also calculated and obtained clearly. The start pressure agreed well with the threshold pressure obtained theoretically. The characteristics of the infiltration in the preform was discussed using a one-dimensional solution of D’Arcy’s law in a centrifugal force field. It was made clear that when preform surface pressure is low, the region having lower pressure than the threshold pressure appears in the infiltrated region.  相似文献   
54.
Summary Carbon blacks were found capable of initiating the ringopening polymerization of 2-substituted-2-oxazolines at relativery high temperatures. The activation energy of the polymerization of 2-methyl-2-oxazoline was estimated to be 13.4 kcal/mol. Carbon black lost the initiating activity of the polymerization upon the blocking of carboxyl groups on the surface by the treatment with potassium hydroxide or diazomethane. Therefore, it was concluded that carboxyl groups on carbon black play an important role in the initiation of the polymerization. Furthermore, it was found that during the polymerization, poly(N-acylethyleneimine) was grafted onto carbon black by the termination of growing polymer chain with the surface.  相似文献   
55.
Continuous stoichiometric silicon nitride fiber was produced by the pyrolysis of perhydropolysilazane. This high-purity silicon nitride fiber is colorless and has high strength, modulus of elasticity, and thermal stability which are properties suitable for reinforcing plastics, metals, glasses, and even ceramics. The structures of three kinds of amorphous silicon nitride fibers (with stoichiometric, Si-excess and O-excess composition) were investigated by X-ray diffraction followed by calculating the radial distribution functions. Radial distribution functions were calculated from several possible crystal structures and compared with observed radial distribution functions.  相似文献   
56.
57.
Rechargeable Mg-ion batteries have gained significant attention as promising alternatives to Li-ion batteries. Owing to its high theoretical energy density and relatively high Mg-ion diffusivity, spinel oxide MgMn2O4 is a viable candidate as a cathode material; however, its poor rate capability limits its applicability. Decreasing the particle size can effectively address this problem by enhancing Mg-ion diffusion. In this paper, we demonstrate the conventional solvothermal synthesis of MgMn2O4 spinel nanoparticles. Solvothermal process is one of the most fundamental methods for nanoparticle synthesis because of its simple and flexible synthetic conditions. In the alcohol solvothermal conditions, spinel type MgMn2O4 nanoparticles of approximately 10–15 nm are successfully synthesized using amorphous MnO2 as a precursor. We note that controlling Mg2+ solvation and oxidation/reduction conditions in the reaction solution is crucial for the effective intercalation of Mg2+ into the MnO6 octahedral framework. Although the obtained MgMn2O4 nanoparticles aggregate to form submicron secondary particles, the aggregation can be suppressed by compositing them with the carbon nanotubes dispersed in the reaction solution. The composite exhibits a discharge capacity of 60 mAh g?1 with maintaining 80% of capacity retention after the 10th cycle.  相似文献   
58.
The authors set out to investigate the durability of the bond between carbon fibre (CF) sheet reinforcement and concrete. They conducted an outdoor exposure test in a moderate climate for 14 years and an immersion test for 6 months on CF sheet bonded to concrete, and then evaluated the adhesive bond properties using the pull-off and peel methods.The pull-off strength slightly decreased after 14 years of exposure, but residual values still indicate quite good adhesive properties. The failure modes for both the initial specimens and the specimens after 14 years of exposure consisted of concrete substrate failures in all cases. This result suggests that the slight decrease in pull-off strength does not necessarily indicate a change in the properties of the bond between CF sheet and concrete. On the other hand, results of the peel tests showed different types of failure modes and seemed more discriminant than those of the pull-off method.As regards specimens immersed in water, pull-off results were in few cases consistent with the peel characterizations, showing significant evolutions in the strength and failure mode. But for most specimens, the two methods provided divergent trends. In the end, this study suggested that the peel test could be relevant for evaluating the durability of the bond between CF sheet and concrete, while the representativeness of the pull-off test remains a matter of discussion.  相似文献   
59.
Zirconia powders doped with C60 molecules were prepared from an aqueous solution of zirconium oxynitrate dihydrate, C60 and C16TMA, and sintered at 600°C under 5.5 GPa for 2 h. C60 was found to be retained in the sintered specimens by HRTEM, and carbon was observed to be uniformly dispersed by the SEM-EDX analysis. HRTEM observations of the sintered specimens exhibited the formation of ZrO2 crystal grains covered with thin graphitic or amorphous carbon films.  相似文献   
60.
We report the first well‐controlled room temperature anionic polymerization of 2‐vinylnaphthalene (2‐VNP), using alkyllithium (RLi) initiators. The nucleophilicity and solubility of the RLi as well as that of the 2‐vinylnaphthalenyllithium (VNPLi) and poly(2‐vinylnaphthalenyl)lithium (PVNPLi) propagating species were found to be very important factors in this reaction. An initiator system composed of n‐butyllithium (n‐BuLi) with tetrahydrofuran (THF) in 1,2,3,4‐tetrahydronaphthalene (THN) was determined to be the most effective of the various systems examined. The n‐BuLi/THF complex initiates polymerization and the resulting VNPLi/THF and PVNPLi/THF complexes act as propagating species at room temperature. These species offer adequate nucleophilicity and stability without promoting side reactions. As a result, rapid anionic polymerization was achieved. Various poly(2‐VNP) products with well‐defined polymeric chain structures were synthesized by this process at room temperature. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41901.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号