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   85篇
  免费   3篇
电工技术   7篇
化学工业   11篇
建筑科学   1篇
能源动力   9篇
轻工业   4篇
无线电   25篇
一般工业技术   8篇
冶金工业   9篇
原子能技术   10篇
自动化技术   4篇
  2022年   2篇
  2021年   2篇
  2019年   1篇
  2018年   1篇
  2017年   1篇
  2016年   1篇
  2015年   1篇
  2014年   2篇
  2013年   3篇
  2012年   2篇
  2011年   2篇
  2010年   2篇
  2009年   1篇
  2008年   2篇
  2006年   5篇
  2005年   6篇
  2003年   1篇
  2002年   3篇
  2001年   2篇
  2000年   3篇
  1999年   6篇
  1998年   5篇
  1997年   3篇
  1996年   5篇
  1995年   4篇
  1994年   3篇
  1993年   6篇
  1992年   3篇
  1990年   2篇
  1985年   1篇
  1984年   3篇
  1980年   1篇
  1979年   1篇
  1978年   1篇
  1977年   1篇
排序方式: 共有88条查询结果,搜索用时 15 毫秒
21.
Quantitative evalution of starch-lipid interaction was attempted by means of amylography, the degree of gelatinization, iodine affinity, iodine color intensity, solubility and swelling power using isolated non-defatted, defatted, and re-embraced or impregnated starch with fatty acids, whose starch was isolated from non-glutinous rice. The data obtained support that characteristics of rice starch are greatly affected by a trace amount of embraced lipid. The saturated amount of lipid in the rice starch might be reasonably deduced to be about 1 % or less. This value estimated from set back and maximum viscosity in amylography is in good agreement with the data obtained already.  相似文献   
22.
BACKGROUND: Because graft arteries are smaller and shorter in living-related liver transplantation (LRLT) than in whole or reduced-size liver transplantation from cadavers, arterial reconstruction is thought to be one of the critical points for success. METHODS: Thirty LRLT patients were classified into two groups: those in whom all graft hepatic arteries were reconstructed (group A), and those whom only had some were reconstructed (group B). In group A 17 patients had a single hepatic artery and three had two hepatic arteries. In group B the thickest one of several arteries was reconstructed, but the others were ligated after pulsatile back-bleeding from their cut stumps had been confirmed. The clinical results were compared between the two groups. RESULTS: Neither arterial thrombosis nor liver dysfunction related to the arterial blood supply was observed during the postoperative course. One case of bile leakage and two cases of bile duct stenosis occurred in group A. No significant difference was noted in the postoperative values of aspartate aminotransferase, alanine aminotransferase, and lactate dehydrogenase between the two groups. Overall patient and graft survival was 90%. CONCLUSIONS: Although several hepatic arteries may supply the potential allograft in LRLT, it is not always necessary to reconstruct all of them.  相似文献   
23.
24.
This paper presents a novel system reduction method which makes it possible to consider the impact of photovoltaic (PV) penetration on transient stability precisely. The object system for system reduction can be aggregated into a simple equivalent circuit by using the proposed method. The equivalent circuit consists of a lumped load model, a lumped PV model, and three equivalent impedances. Using the equivalent circuit, power flow into the object system when the system voltage changes can be analyzed without repeated power flow calculation of the original system. In order to verify the proposed method, this paper presents a numerical example of transient stability analysis with a one‐generator‐to‐infinite‐bus system model. The results of analysis indicate that transient stability considering PV penetration can be analyzed with high accuracy with the proposed method.  相似文献   
25.
The temperature dependence of luminescence from [Cu(dnbp)(DPEPhos)]BF4 (dnbp = 2,9‐di‐n‐butylphenanthroline, DPEPhos = bis[2‐(diphenylphosphino)phenyl]ether) in a poly(methyl methacrylate) (PMMA) film indicates the presence of long‐life green emission arising from two thermally equilibrated charge transfer (CT) excited states and one non‐equilibrated triplet ligand center (3LC) excited state. At room temperature, the lower triplet CT state is found to be the predominantly populated excited state, and the zero‐zero energy of this state is found to be 2.72 eV from the onset of its emission at 80 K. The tunable emission maximum of [Cu(dnbp)(DPEPhos)]BF4 in various hosts with different triplet energies is explained in terms of the multiple triplet energy levels of this complex in amorphous films. Using the high triplet energy charge transport material as a host and an exciton‐blocking layer (EBL), a [Cu(dnbp)(DPEPhos)]BF4 based organic light‐emitting diode (OLED) achieves a high external quantum efficiency (EQE) of 15.0%, which is comparable to values for similar devices based on Ir(ppy)3 and FIrpic. The photoluminescence (PL) and electroluminescence (EL) performance of green emissive [Cu(μI)dppb]2 (dppb = 1,2‐bis[diphenylphosphino]benzene) in organic semiconductor films confirmed its 3CT state with a zero‐zero energy of 2.76 eV as the predominant population excited state.  相似文献   
26.
The homeobox gene otx2 is a key regulator for specifying the rostral part of the vertebrate head. In Xenopus, otx2 directly controls the differentiation of the cement gland, the anterior-most organ formed in the tadpole. Since embryos of a direct developing frog, Eleutherodactylus coqui, lack a cement gland, we are interested in whether altered expression of the otx2 gene is involved in this evolutionary change. We have cloned the E. coqui homologue of otx2, Ecotx2. The homeodomain of the Ecotx2 protein is identical to the mouse and zebrafish Otx2 proteins and differs by a single amino acid from the Xenopus Otx2 protein. Study of the spatiotemporal expression pattern shows that Ecotx2 RNA is progressively restricted to the anterior region of the embryo during gastrulation and becomes further restricted to the future forebrain and midbrain during neural development. In Xenopus, in addition to the conserved expression in the anterior neuroectoderm, the expression in ectoderm expands more anteriorly to the cement gland primordium. This anterior expansion of otx2 expression is not found in E. coqui, correlating with the loss of a cement gland. When misexpressed in Xenopus laevis ectoderm, Ecotx2 can activate expression of the cement-gland-specific genes XCG and XAG1, indicating that the function of activating the pathway of cement gland formation is retained by the Ecotx2 protein. Our results indicate that there are modifications in the pathway of cement gland formation, upstream of otx2 expression, in the development of E. coqui.  相似文献   
27.
We study the atomic mixing at metal (Bi or Au)/oxide (SiO2 or Al2O3) interfaces under 150–200 MeV heavy ion irradiation. Irradiation-induced interface mixing state is examined by means of Rutherford backscattering spectrometry (RBS). For Bi/Al2O3 interfaces, the heavy ion irradiations induce a strong atomic mixing and the amount of the mixing increases with increasing the electronic stopping power for heavy ions. By comparing the results with that for 3 MeV Si ion irradiation, we conclude that the strong atomic mixing observed at Bi/Al2O3 interfaces is attributed to the high-density electronic excitation. On the other hand, for other interfaces (Bi/SiO2, Au/Al2O3 and Au/SiO2), atomic mixing is rarely observed after the irradiation. The dependence of atomic mixing on combinations of irradiating ions and interface-forming materials is discussed.  相似文献   
28.
It is unclear whether the menstrual cycle affects the basics of performance, mainly task performance and cognitive functions. We examined menstrual cycle effects on VDT-based task performance, cognitive indices based on the signal-detection theory, and subjective ratings in questionnaires. We experimented in three phases: premenstrual, menstrual and postmenstrual phases. Previous studies reported premenstrual tension syndrome (PMST) in the premenstrual phase. Women used physiological and psychological strategies to cope during the menstrual phase. However, task performance, cognitive indices and subjective ratings showed no menstrual cycle effects. Thus, we can conclude that the information processing for the VDT-based task was not affected by menstrual cycle.  相似文献   
29.
An interface modification by hydrocarbon radicals from cracked-propane (C3H8) and dimethylgermane ((CH3)2GeH2:DMGe) in heteroepitaxy of 3C-SiC on Si has been studied with in situ reflection high-energy electron diffraction (RHEED) and a high-resolution scanning electron microscope. In the case of cracked-C3H8, a clean Si surface is carbonized at 750°C. Whereas, in the case of DMGe, it can be carbonized reproducibly at as low as 650°C. A RHEED pattern of a carbonized layer prepared using DMGe indicates single-crystalline 3C-SiC without twins and Ge-related patterns. The activation energy in the range of 46.9-51.1 kcal/ mol is obtained in the initial stage of 3C-SiC growth for both hydrocarbon sources. The difference in 3C-SiC growth by using different hydrocarbon sources is discussed in detail.  相似文献   
30.
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