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   316篇
  免费   34篇
  国内免费   3篇
电工技术   4篇
综合类   1篇
化学工业   124篇
金属工艺   4篇
机械仪表   6篇
建筑科学   7篇
能源动力   10篇
轻工业   43篇
水利工程   6篇
石油天然气   5篇
武器工业   1篇
无线电   26篇
一般工业技术   75篇
冶金工业   3篇
原子能技术   2篇
自动化技术   36篇
  2024年   2篇
  2023年   5篇
  2022年   21篇
  2021年   27篇
  2020年   20篇
  2019年   27篇
  2018年   29篇
  2017年   39篇
  2016年   26篇
  2015年   14篇
  2014年   25篇
  2013年   27篇
  2012年   17篇
  2011年   19篇
  2010年   12篇
  2009年   3篇
  2008年   8篇
  2007年   4篇
  2006年   2篇
  2005年   2篇
  2004年   2篇
  2003年   1篇
  2002年   1篇
  2001年   2篇
  2000年   2篇
  1999年   1篇
  1998年   1篇
  1997年   1篇
  1996年   1篇
  1995年   1篇
  1994年   3篇
  1992年   1篇
  1989年   2篇
  1982年   1篇
  1977年   1篇
  1975年   1篇
  1974年   2篇
排序方式: 共有353条查询结果,搜索用时 15 毫秒
71.
Polycystic ovary syndrome (PCOS) is the most common endocrine and metabolic disorder in reproductive-aged women, and it typically involves elevated androgen levels. Recently, it has been reported that human bone marrow mesenchymal stem cells (hBM-MSCs) can regulate androgen synthesis pathways. However, the details of the mechanism are still unclear. hBM-MSC-derived secreted factors (the secretome) are promising sources of cell-based therapy as they consist of various types of proteins. It is thus important to know which proteins interact with disease-implicated biomolecules. This work aimed to investigate which secretome components contain the key factor that inhibits testosterone synthesis. In this study, we fractionated hBM-MSC-conditioned media into three fractions based on their molecular weights and found that, of the three fractions, one had the ability to inhibit the androgen-producing genes efficiently. We also analyzed the components of this fraction and established a protein profile of the hBM-MSC secretome, which was shown to inhibit androgen synthesis. Our study describes a set of protein components present in the hBM-MSC secretome that can be used therapeutically to treat PCOS by regulating androgen production for the first time.  相似文献   
72.
The increasing demand on execution of large-scale Cloud workflow applications which need a robust and elastic computing infrastructure usually lead to the use of high-performance Grid computing clusters. As the owners of Cloud applications expect to fulfill the requested Quality of Services (QoS) by the Grid environment, an adaptive scheduling mechanism is needed which enables to distribute a large number of related tasks with different computational and communication demands on multi-cluster Grid computing environments. Addressing the problem of scheduling large-scale Cloud workflow applications onto multi-cluster Grid environment regarding the QoS constraints declared by application’s owner is the main contribution of this paper. Heterogeneity of resource types (service type) is one of the most important issues which significantly affect workflow scheduling in Grid environment. On the other hand, a Cloud application workflow is usually consisting of different tasks with the need for different resource types to complete which we call it heterogeneity in workflow. The main idea which forms the soul of all the algorithms and techniques introduced in this paper is to match the heterogeneity in Cloud application’s workflow to the heterogeneity in Grid clusters. To obtain this objective a new bi-level advanced reservation strategy is introduced, which is based upon the idea of first performing global scheduling and then conducting local scheduling. Global-scheduling is responsible to dynamically partition the received DAG into multiple sub-workflows that is realized by two collaborating algorithms: (1) The Critical Path Extraction algorithm (CPE) which proposes a new dynamic task overall critically value strategy based on DAG’s specification and requested resource type QoS status to determine the criticality of each task; and (2) The DAG Partitioning algorithm (DAGP) which introduces a novel dynamic score-based approach to extract sub-workflows based on critical paths by using a new Fuzzy Qualitative Value Calculation System to evaluate the environment. Local-scheduling is responsible for scheduling tasks on suitable resources by utilizing a new Multi-Criteria Advance Reservation algorithm (MCAR) which simultaneously meets high reliability and QoS expectations for scheduling distributed Cloud-base applications. We used the simulation to evaluate the performance of the proposed mechanism in comparison with four well-known approaches. The results show that the proposed algorithm outperforms other approaches in different QoS related terms.  相似文献   
73.
Magnesium aluminate (MgAl2O4) spinel precursor sol was prepared using aluminum nitrate and magnesium nitrate as the precursors for alumina and magnesia, respectively. The obtained sol owned a translucent, homogenous, and stable appearance with a density of 1.19 g/cm3, and at the temperatures above 60 °C, converted to a soft and clear gel. The measured pH of sol was in the range of 3–4, and at the calcination temperature of 1000 °C, the solid content of 6% was reached. TGA/DSC analysis was utilized to study the thermal behavior of the sol. Fourier transforms infrared spectroscopy (FTIR) was applied to recognize the existing bounds in the dried and calcined sol. X-ray diffraction patterns revealed the formation of single-phase MgAl2O4 up to 600 °C. According to the FESEM images, the grain size for the sol calcined at 1000 °C was estimated at around 50 nm.  相似文献   
74.
Atherosclerosis is a major cause of human cardiovascular disease, which is the leading cause of mortality around the world. Various physiological and pathological processes are involved, including chronic inflammation, dysregulation of lipid metabolism, development of an environment characterized by oxidative stress and improper immune responses. Accordingly, the expansion of novel targets for the treatment of atherosclerosis is necessary. In this study, we focus on the role of foam cells in the development of atherosclerosis. The specific therapeutic goals associated with each stage in the formation of foam cells and the development of atherosclerosis will be considered. Processing and metabolism of cholesterol in the macrophage is one of the main steps in foam cell formation. Cholesterol processing involves lipid uptake, cholesterol esterification and cholesterol efflux, which ultimately leads to cholesterol equilibrium in the macrophage. Recently, many preclinical studies have appeared concerning the role of non-encoding RNAs in the formation of atherosclerotic lesions. Non-encoding RNAs, especially microRNAs, are considered regulators of lipid metabolism by affecting the expression of genes involved in the uptake (e.g., CD36 and LOX1) esterification (ACAT1) and efflux (ABCA1, ABCG1) of cholesterol. They are also able to regulate inflammatory pathways, produce cytokines and mediate foam cell apoptosis. We have reviewed important preclinical evidence of their therapeutic targeting in atherosclerosis, with a special focus on foam cell formation.  相似文献   
75.
Journal of Housing and the Built Environment - Although Abu Dhabi and Dubai have similar political and planning systems, the two cities’ neighborhoods feature different morphological layouts....  相似文献   
76.
Amiri  Sahar 《SILICON》2019,11(3):1193-1203
Silicon - A novel poly(acrylamide)/ clay mineral composite was synthesized by controlled radical polymerization of acrylamide, clay minerals using potassium persulfate (KPS) and N,...  相似文献   
77.
Cell–cell communication is an essential mechanism for the maintenance and development of various organs, including the female reproductive system. Today, it is well-known that the function of the female reproductive system and successful pregnancy are related to appropriate follicular growth, oogenesis, implantation, embryo development, and proper fertilization, dependent on the main regulators of cellular crosstalk, exosomes. During exosome synthesis, selective packaging of different factors into these vesicles happens within the originating cells. Therefore, exosomes contain both genetic and proteomic data that could be applied as biomarkers or therapeutic targets in pregnancy-associated disorders or placental functions. In this context, the present review aims to compile information about the potential exosomes with key molecular cargos that are dysregulated in female reproductive diseases which lead to infertility, including polycystic ovary syndrome (PCOS), premature ovarian failure (POF), Asherman syndrome, endometriosis, endometrial cancer, cervical cancer, ovarian cancer, and preeclampsia, as well as signaling pathways related to the regulation of the reproductive system and pregnancy outcome during these pathological conditions. This review might help us realize the etiology of reproductive dysfunction and improve the early diagnosis and treatment of the related complications.  相似文献   
78.
BACKGROUND: Salmeterol xinafoate is a highly selective beta2-adrenoceptor for the maintenance treatment of asthma in adults and children. OBJECTIVE: To review the pharmacokinetics, clinical pharmacology, and therapeutic properties of a recently introduced, long acting antiasthmatic drug. METHODS: Recent English-language publications were selected using Medline as database. RESULTS: Salmeterol's pharmacokinetics, clinical pharmacology, and therapeutic properties are reviewed and aspects related to salmeterol's unusual duration of action, its high potency, beta2-selectivity, possible antiinflammatory actions, its interaction with other drugs, low systemic adverse effects, dosage, and administration are also discussed. CONCLUSION: Salmeterol is a safe long-acting beta2-agonist very useful for maintenance treatment of asthma.  相似文献   
79.
Wireless Personal Communications - Smart cities are benefiting from Internet of Things (IoT) in optimizing their services. Smart waste management systems can provide substantial savings in time,...  相似文献   
80.
Optimized doped TiO2 is necessary for efficient visible light harvesting and widening the applications spectrum of TiO2-based materials. Titanium dioxide doped with silver and/or vanadium has been synthesized by one-pot hydrothermal method without post-calcination. Codoping induced visible light absorption while maintaining the photoactive anatase phase along with good crystallinity. Synthesized products are in nanometer range and possess high specific surface area. Having nearly spherical morphology, the particles are distributed and the particle size estimated from TEM observation is in accordance with the XRD results. Spectroscopic investigations reveal that the doped atoms successfully entered the TiO2 lattice modifying the band structure. The narrowed band gap allows visible light photons for absorption, and the codoped samples displayed enhanced visible light absorption among the synthesized samples. Photodegradation performance evaluated under visible light irradiations showed that silver- , vanadium-codoped TiO2 have the best visible light photocatalytic activity attributed to stable configuration, high visible light absorption, coupling between silver and vanadium and their optimal doping concentration.  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