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   131篇
  免费   3篇
  国内免费   1篇
电工技术   2篇
化学工业   23篇
金属工艺   2篇
机械仪表   6篇
能源动力   1篇
轻工业   12篇
水利工程   1篇
石油天然气   1篇
无线电   16篇
一般工业技术   19篇
冶金工业   22篇
自动化技术   30篇
  2024年   2篇
  2022年   6篇
  2021年   6篇
  2020年   5篇
  2019年   3篇
  2018年   4篇
  2017年   1篇
  2016年   7篇
  2015年   3篇
  2014年   10篇
  2013年   14篇
  2012年   4篇
  2011年   5篇
  2010年   8篇
  2009年   7篇
  2008年   3篇
  2007年   8篇
  2006年   4篇
  2005年   2篇
  2002年   2篇
  1999年   1篇
  1998年   8篇
  1997年   4篇
  1996年   2篇
  1995年   1篇
  1993年   2篇
  1990年   1篇
  1985年   1篇
  1983年   1篇
  1982年   1篇
  1981年   1篇
  1979年   1篇
  1978年   1篇
  1977年   2篇
  1976年   2篇
  1975年   1篇
  1974年   1篇
排序方式: 共有135条查询结果,搜索用时 15 毫秒
11.
Abstract

Inventory management deals with a tradeoff between the benefits of keeping stocks of goods that allows fulfillment of the customer’s demand, and the cost of carrying inventory. Inventory control techniques are very important components and the most organizations can substantially reduce their costs associated with the flow of materials. This paper presents new inventory management model based on particle swarm optimization and pure adaptive search global optimization algorithm in production-inventory system. The proposed model is focusing on planned level of demand for finished goods, production and raw materials cost, production capacity as the norm, change of the production cost and inventory capital cost, all of which are typical factors in automobile manufacture industry. The model determines different factors such as the minimizing inventory quantity, minimizing inventory value, and minimizing production cost based on demand for production items. The model is tested with original real-world dataset obtained from the automotive company Lear from US and its factory in Novi Sad, Serbia.  相似文献   
12.
13.
Galectins are a family of conserved soluble proteins defined by an affinity for β-galactoside structures present on various glycoconjugates. Over the past few decades, galectins have been recognized as important factors for successful implantation and maintenance of pregnancy. An increasing number of studies have demonstrated their involvement in trophoblast cell function and placental development. In addition, several lines of evidence suggest their important roles in feto-maternal immune tolerance regulation and angiogenesis. Changed or dysregulated galectin expression is also described in pregnancy-related disorders. Although the data regarding galectins’ clinical relevance are still at an early stage, evidence suggests that some galectin family members are promising candidates for better understanding pregnancy-related pathologies, as well as predicting biomarkers. In this review, we aim to summarize current knowledge of galectins in early pregnancy as well as in pregnancy-related pathologies.  相似文献   
14.
Non-heme Fe(IV)-oxo intermediates   总被引:1,自引:0,他引:1  
High-valent non-heme iron-oxo intermediates have been proposed for decades as the key intermediates in numerous biological oxidation reactions. In the past three years, the first direct characterization of such intermediates has been provided by studies of several alphaKG-dependent oxygenases that catalyze either hydroxylation or halogenation of their substrates. In each case, the Fe(IV)-oxo intermediate is implicated in cleavage of the aliphatic C-H bond to initiate hydroxylation or halogenation. The observation of non-heme Fe(IV)-oxo intermediates and Fe(II)-containing product(s) complexes with almost identical spectroscopic parameters in the reactions of two distantly related alphaKG-dependent hydroxylases suggests that members of this subfamily follow a conserved mechanism for substrate hydroxylation. In contrast, for the alphaKG-dependent non-heme iron halogenase, CytC3, two distinct Fe(IV) complexes form and decay together, suggesting that they are in rapid equilibrium. The existence of two distinct conformers of the Fe site may be the key factor accounting for the divergence of the halogenase reaction from the more usual hydroxylation pathway after C-H bond cleavage. Distinct transformations catalyzed by other mononuclear non-heme enzymes are likely also to involve initial C-H bond cleavage by Fe(IV)-oxo complexes, followed by diverging reactivities of the resulting Fe(III)-hydroxo/substrate radical intermediates.  相似文献   
15.
We have analyzed all available data including birth certificates, maternity records, pediatric records, and pathology reports of spontaneous and induced abortions and newborn deaths to determine the frequency of congenital anomalies of the central nervous system. We found 76 infants (34 males, 39 females and 3 of undetermined sex) with CNS anomalies during the 1990-93 period. In the same period there were 23,425 births. The frequency of CNS anomalies in this period was 32,4/10,000 births. These results are at variance with conclusions of previously published and incomprehensive studies in Croatia. Therefore, a systematic follow-up of the autopsy findings of induced and spontaneous abortions and newborn deaths in the epidemiology of CNS anomalies is clearly needed.  相似文献   
16.
The effect of human recombinant (hr) thrombopoietin (TPO) on human megakaryocytopoiesis was studied in a serum-free system. hrTPO induced megakaryocyte colony formation by purified CD 34-positive cells and polyploidization of megakaryocytes by purified CD41a-positive cells. hrTPO gave rise to much smaller colonies which appeared at an earlier time compared to the use of human recombinant interleukin-3 (hrIL-3), suggesting that hrTPO predominantly affects the population of megakaryocyte progenitor cells in the late stage. hrIL-3 additively increased the hrTPO-induced megakaryocyte colony formation by CD34-positive cells. The hrTPO-induced megkaryocyte colony formation was also increased by the presence of hrIL-6, hrIL-11, human recombinant erythropoietin (hrEpo) or human recombinant stem cell factor (hrSCF), none of which stimulated megakaryocyte colony growth when added alone. The combined addition of hrTPO, hrIL-3 and hrSCF to CD34-positive cells markedly stimulated megakaryocyte colony formation and produced large numbers of megakaryocytes. hrTPO stimulated the polyploidization of CD34-positive cell-derived megakaryocytes in liquid culture. However, the addition of hrIL-6, hrIL-11 or hrEpo to hrTPO did not further enhance the hrTPO-induced polyploidization. These findings indicate that at the megakaryocyte progenitor cell level, the effect of hrTPO can be promoted by the presence of various hematopoietic growth factors involved in human megakaryocytopoiesis.  相似文献   
17.
OLED技术是显示领域的热点技术,国内企业在加大研发力度的同时,将面临如何进行专利布局以有效保护研究成果的问题.本文重点探讨了三星公司在OLED领域的中国专利申请情况及其特点.通过专利状况分析,对研究OLED行业的发展趋势以及使国内相关企业做好专利防范具有重要的参考意义.  相似文献   
18.
Intermetallics phases along Mo–Pt phase diagram have been investigated as cathode materials for the production of hydrogen by electrolysis from water KOH solutions, in an attempt to increase the electrolytic process efficiency. These materials were compared with conventional cathodes (Fe and Ni), often used in the alkaline electrolysis, and also with the intermetallic Ti–Pt. An significant upgrade of the electrolytic efficiency using intermetallics in pure KOH electrolyte was achieved in comparison with conventional cathode materials.  相似文献   
19.
Molecular imaging enables the non-invasive investigation of cellular and molecular processes. Although there are challenges to overcome, the development of targeted contrast agents to increase the sensitivity of molecular imaging techniques is essential for their clinical translation. In this study, spontaneously forming, small unilamellar vesicles (sULVs) (30 nm diameter) were used as a platform to build a bimodal (i.e., optical and magnetic resonance imaging (MRI)) targeted contrast agent for the molecular imaging of brain tumors. sULVs were loaded with a gadolinium (Gd) chelated lipid (Gd-DPTA-BOA), functionalized with targeting antibodies (anti-EGFR monoclonal and anti-IGFBP7 single domain), and incorporated a near infrared dye (Cy5.5). The resultant sULVs were characterized in vitro using small angle neutron scattering (SANS), phantom MRI and dynamic light scattering (DLS). Antibody targeted and nontargeted Gd loaded sULVs labeled with Cy5.5 were assessed in vivo in a brain tumor model in mice using time domain optical imaging and MRI. The results demonstrated that a spontaneously forming, nanosized ULVs loaded with a high payload of Gd can selectively target and image, using MR and optical imaging, brain tumor vessels when functionalized with anti-IGFBP7 single domain antibodies. The unique features of these targeted sULVs make them promising molecular MRI contrast agents.  相似文献   
20.
Naulleau PP  George SA 《Applied optics》2011,50(19):3346-3350
In the case of extreme ultraviolet (EUV) lithography, modeling has shown that reflector phase roughness on the lithographic mask is a significant concern due to the image plane speckle it causes and the resulting line-edge roughness on imaged features. Modeling results have recently been used to determine the requirements for future production worthy masks yielding the extremely stringent specification of 50 pm rms roughness. Owing to the scale of the problem in terms of memory requirements, past modeling results have been based on the thin mask approximation in this application. EUV masks, however, are inherently three-dimensional (3D) in nature and thus the question arises as to the validity of the thin mask approximation. Here, we directly compare the image plane speckle calculation results using the fast two-dimensional thin mask model to rigorous finite-difference time-domain results and find the two methods to agree to within 10% in the computation of the speckle magnitude and 20% in the computation of the line-edge roughness limited depth of focus. For both types of computation, the two-dimensional method provides a conservative estimate. The 3D modeling is also used to show that layer-to-layer correlated roughness is indeed the roughness metric of most concern.  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