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1.
The mechanisms that control lipolysis in intra-abdominal fat cells from various primate species, the marmoset (Callithrix jacchus), the baboon (Papio papio), and the macaque (Macaca fascicularis), were compared to those of human intraabdominal fat cells. Selective beta 1- or beta 2-adrenoceptor agonists induced lipolysis in all species. Selective beta 3-agonists (BRL 37344, CL 316243, and SR 58611) acted as partial agonists in marmoset but were inefficient in other primates, including humans. alpha 2-Adrenoceptor number ([3H]RX 8210002 binding) equalized (baboon) or exceeded (other primates) beta 1/beta 2-adrenoceptors ([3H]CGP 12177 binding). Baboon fat cell membranes expressed similar amounts of coupled beta- and alpha 2-adrenoceptors. In all species, norepinephrine- or epinephrine-induced lipolysis did not reach the lipolytic effect of isoproterenol but their effects were enhanced after alpha 2-adrenoceptor blockade. N6-phenylisopropyladenosine (PIA) induced a full antilipolytic effect in baboon, macaque, and human adipocytes through adenosine receptors ([3H]DPCPX binding). Peptide YY (PYY) weakly inhibited lipolysis in baboon. Adrenocorticotropic hormone (ACTH) was inactive whereas parathyroid hormone (PTH) partially stimulated lipolysis in primates. Histamine was partially lipolytic in marmoset only. This study emphasizes the similarities of the mechanisms controlling the lipolysis in nonhuman primate and in human adipocytes and suggests that the baboon and the macaque should provide unique models for the study of the regulation of lipolysis.  相似文献   
2.
结合我国放顶煤开采的实践,对放顶煤工作面顶煤的破碎和移动规律及上覆岩层的活动规律进行了研究,指出了开采深度、煤层强度、支架支护强度及煤层厚度等是影响顶煤破碎和放顶煤效果的主要因素。同时指出了顶煤的破碎是顶煤与上覆岩层相互作用的结果,而支架仅起辅助破煤的作用。并在此提出了顶煤破碎分区。  相似文献   
3.
The purpose of the present study was to evaluate the ability of LaFeO3 perovskites prepared using the “self-combustion method” to behave as efficient and stable catalysts in phenol oxidation using H2O2 in ambient conditions. Depending on the synthesis conditions, strong differences in the structural, textural and reducibility characteristics of the perovskites, as well as in phenol conversion and TOC abatement level were observed. High TOC abatement (76%) and very low iron leaching (0.27 wt%) were obtained at 40 °C in the presence of LaFeO3 nanoparticles exhibiting the lowest crystal domain size.  相似文献   
4.
Brown adipose tissue (BAT) is involved in the control of energy balance and has been demonstrated to be activated through beta 3-adrenoceptor (beta 3-AR) occupation in rodents. The ability to specifically activate energy expenditure via this receptor is of great interest for the treatment of obesity. Nevertheless, the extent of BAT and the presence of a functional beta 3-AR in humans are now debated, and this situation is difficult to clarify for evident practical and ethical reasons. We investigated the occurrence of brown adipocytes in fat deposits of prepubertal baboons using antibodies raised against uncoupling protein (UCP) in Western blotting and immunocytology experiments. UCP was detected in all types of fat pads studied and was revealed in multilocular cells. Pericardiac and axillary adipose tissues displayed large amounts of UCP and can be assimilated to typical BAT. Most of the other pads looked like white adipose tissue, but exhibited areas with clusters of brown adipocytes and, thus, can be assimilated to the convertible adipose tissue as previously described in rodents. The presence of beta 3-ARs was evaluated by both beta 2-agonist-stimulated lipolysis and messenger ribonucleic acid (mRNA) expression studies. There was no significant lipolytic effect of any of the beta 3-AR agonists tested (SR 58611A, BRL 37344, CGP 12177, or CL 316243) in either white or brown tissues. PCR analysis demonstrated that beta 3-AR mRNA expression is not related to the UCP content of fat pads and that beta 3-AR expression is low. This study demonstrates the presence of great proportions of brown adipocytes in adipose tissue and the heterogeneity of the fat pads in baboons. The lack of a metabolic effect of beta 3-agonists combined with the weak expression of beta 3-AR mRNAs raise the question of the role of beta 3-ARs in adipose tissues of primates.  相似文献   
5.
We investigated changes in the occurrence of allelochemicals from leachates of different Pinus halepensis organs taking into account the stages of pine stand age (i.e., young  < 15-years-old, middle age ± 30-years, and old  > 60-years-old). GC-MS analysis of aqueous extracts revealed approx. 59 components from needles and roots. The major constituents were divided into different phytochemical groups—phenolics (50%), fatty acids (44%), and terpenoids. Further analyses were carried out to characterize the distribution of allelochemicals in different organs and P. halepensis successional stages. Roots and needles had two distinct chemical profiles, while needle leachates were composed mainly of oxygenated terpenoids (e.g., α-eudesmol, α-cadinol, and α-terpineol). Roots mainly contained fatty acids. Needles from young pine stands had the highest content of monoterpenes, suggesting their role as potential allelochemicals that could help young pine stands to establish. Pooling the different functional chemical groups showed that needles and, to a lesser extent, old roots, had higher chemical diversity than the roots of young and medium-aged pines. The highest diversity in phenolic constituents and fatty acids was in young needles (Dchem = 2.38). Finally, caffeic acid, a compound that has allelopathic properties was found in aqueous extracts at high concentrations in both young needles and old roots. The role of this compound in mediation of biological interactions in P. halepensis ecosystem functioning is discussed.  相似文献   
6.
根据一般飞机发动机转子的结构特点,制造精度等及其在制造厂或大修厂中实际平衡、装配的工艺过程,分析了发动机转子装配到发动机机壳上后发动机整机不平衡量增大的诸因素,推导出了飞机发动机转子及整机不平衡量的计算公式,提出了飞机发动机整机不平衡增量产生根源的新概念和正确定量评估飞机发动机整机不平衡量大小的新方法,对飞机发动机的装配和可行性研究提供了依据。  相似文献   
7.
分析了 CO2 气体保护焊接工艺在变压器行业中应用的难点 ,提出了解决这些难点的措施和办法  相似文献   
8.
The diagnosis problem for discrete event systems consists in deciding whether some fault event occurred or not in the system, given partial observations on the run of that system. Diagnosability checks whether a correct diagnosis can be issued in bounded time after a fault, for all faulty runs of that system. This problem appeared two decades ago and numerous facets of it have been explored, mostly for permanent faults. It is known for example that diagnosability of a system can be checked in polynomial time, while the construction of a diagnoser is exponential. The present paper examines the case of transient faults, that can appear and be repaired. Diagnosability in this setting means that the occurrence of a fault should always be detected in bounded time, but also before the fault is repaired, in order to prepare for the detection of the next fault or to take corrective measures while they are needed. Checking this notion of diagnosability is proved to be PSPACE-complete. It is also shown that faults can be reliably counted provided the system is diagnosable for faults and for repairs.  相似文献   
9.
楼应侯  金寿松 《机电工程》1999,16(5):163-164
提出了不限于目前常见的AGV 或输送带等单一设备的系统模式,而代之以人、车辆、传送带、小车等各类输送设备为对象的混合型物流系统的设计思想。在物流系统及其设计中,强调人的作用,人—机的合理分工,良好的人—机界面及采用面向对象的设计方法  相似文献   
10.
This article discusses Al-Cu-Li 2050 alloy developed, qualified, and produced by Alcan Aerospace as plates. AA2050 alloy offers a low density high corrosion resistant alternative to incumbent medium to thick plate alloys like 7050-T7451, and to thin plate alloys like 2024 or higher damage tolerant versions. The fundamentals behind the choice of the Al-Cu-Li chemistry are highlighted, as well as the property balance generated in a wide range of thickness from 12 to 127 mm (0.5 to 5 in.). Manufacturing behavior of the alloy when machining or friction stir welding is also discussed in detail. Finally, it is shown that the appropriate recycling investments and logistics permit the use of 2050 alloy at an acceptable level of extra cost per kilo saved, when weight benefits are taken into account.  相似文献   
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