全文获取类型
收费全文 | 4858篇 |
免费 | 276篇 |
国内免费 | 8篇 |
专业分类
电工技术 | 62篇 |
综合类 | 8篇 |
化学工业 | 929篇 |
金属工艺 | 56篇 |
机械仪表 | 78篇 |
建筑科学 | 181篇 |
矿业工程 | 5篇 |
能源动力 | 160篇 |
轻工业 | 339篇 |
水利工程 | 54篇 |
石油天然气 | 35篇 |
无线电 | 403篇 |
一般工业技术 | 1210篇 |
冶金工业 | 662篇 |
原子能技术 | 15篇 |
自动化技术 | 945篇 |
出版年
2024年 | 13篇 |
2023年 | 59篇 |
2022年 | 96篇 |
2021年 | 141篇 |
2020年 | 113篇 |
2019年 | 122篇 |
2018年 | 127篇 |
2017年 | 137篇 |
2016年 | 162篇 |
2015年 | 135篇 |
2014年 | 190篇 |
2013年 | 333篇 |
2012年 | 318篇 |
2011年 | 387篇 |
2010年 | 298篇 |
2009年 | 285篇 |
2008年 | 311篇 |
2007年 | 247篇 |
2006年 | 217篇 |
2005年 | 191篇 |
2004年 | 157篇 |
2003年 | 135篇 |
2002年 | 128篇 |
2001年 | 67篇 |
2000年 | 62篇 |
1999年 | 65篇 |
1998年 | 67篇 |
1997年 | 52篇 |
1996年 | 54篇 |
1995年 | 46篇 |
1994年 | 47篇 |
1993年 | 39篇 |
1992年 | 38篇 |
1991年 | 23篇 |
1990年 | 29篇 |
1989年 | 17篇 |
1988年 | 18篇 |
1987年 | 33篇 |
1986年 | 18篇 |
1985年 | 28篇 |
1984年 | 15篇 |
1983年 | 7篇 |
1982年 | 13篇 |
1981年 | 20篇 |
1980年 | 8篇 |
1977年 | 8篇 |
1976年 | 10篇 |
1975年 | 9篇 |
1973年 | 8篇 |
1971年 | 6篇 |
排序方式: 共有5142条查询结果,搜索用时 15 毫秒
101.
The aim of this study was to evaluate the suitability of Methylene Blue (MB) and Vitamin B12 (Vit-B12) as water soluble inner aqueous phase (W1) markers for measuring the encapsulation efficiency and stability of water-in-oil-in-water (W1/O/W2) double emulsions stabilized by sodium caseinate (NaCN). The encapsulation efficiency and stability were determined by centrifugation of the double emulsion to separate the cream phase (W1/O) and the outer aqueous phase (W2) and measuring the concentration of marker in W2 by absorbance spectrophotometry. To validate this method the marker concentration measurable and the stability of the marker in W2 were measured. Both markers could be accurately measured in W2 and there was no change in the concentration of marker on storage of a W2 solution for 7 days at 45 °C. The recovery yields of MB and Vit-B12 in the recovered W2 of an oil-in-water (O/W2) emulsion, determined using the procedure normally used for measuring encapsulation efficiency and stability, were 78% and 99%, respectively, and 52 and 100%, respectively. Double emulsions had encapsulation efficiency of 61.9 ± 21.4% and 16.6 ± 1.1% and encapsulation stability of 62.0 ± 22.6% and 10.7 ± 0.7% for MB and Vit-B12, respectively. Recovery yield and encapsulation efficiency/stability data for MB indicate that it is not a suitable marker for measuring the encapsulation properties of NaCN stabilized double emulsions while similar data for Vit-B12 indicate that it is a suitable marker for studying the encapsulation properties of double emulsions stabilized with NaCN. Methods used in other studies to measure encapsulation properties of double emulsions are discussed in light of the results obtained in this study. 相似文献
102.
Jonathan Lesser 《Natural Gas \u0026amp; Electricity》2016,32(9):1-6
No other environmental issue today is the subject of more discussion, debate, and media coverage than human-induced climate change, which is supposedly caused by increasing emissions of carbon dioxide (CO2) from the combustion of fossil fuels. These debates cover everything from basic questions of physical measurement—How has the earth's climate changed over time? How may the climate change in the future because of increased CO2 concentrations in the atmosphere?—to debates over how increased CO2 emissions will affect the economic well-being of future generations. 相似文献
103.
Impact of the Cd2+ treatment on the electrical properties of Cu2ZnSnSe4 and Cu(In,Ga)Se2 solar cells
Khaled Ben Messaoud Marie Buffire Guy Brammertz Hossam ElAnzeery Souhaib Oueslati Jonathan Hamon Bas J. Kniknie Marc Meuris Mosbah Amlouk Jef Poortmans 《Progress in Photovoltaics: Research and Applications》2015,23(11):1608-1620
The present contribution aims at determining the impact of modifying the properties of the absorber/buffer layer interface on the electrical performance of Cu2ZnSnSe4 (CZTSe) thin‐film solar cells, by using a Cd2+ partial electrolyte (Cd PE) treatment of the absorber before the buffer layer deposition. In this work, CZTSe/CdS solar cells with and without Cd PE treatment were compared with their respective Cu(In,Ga)Se2 (CIGSe)/CdS references. The Cd PE treatment was performed in a chemical bath for 7 min at 70 °C using a basic solution of cadmium acetate. X‐ray photoemission spectroscopy measurements have revealed the presence of Cd at the absorber surface after the treatment. The solar cells were characterized using current density–voltage (J–V), external quantum efficiency, and drive‐level capacitance profiling measurements. For the CZTSe‐based devices, the fill factor increased from 57.7% to 64.0% when using the Cd PE treatment, leading to the improvement of the efficiency (η) from 8.3% to 9.0% for the best solar cells. Similar observations were made on the CIGSe solar cell reference. This effect comes from a considerable reduction of the series resistance (RS) of the dark and light J–V, as determined using the one‐diode model. The crossover effect between dark and light J–V curves is also significantly reduced by Cd PE treatment. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
104.
Frank Greenway Brian Loveridge Richard M. Grimes Tori R. Tucker Michael Alexander Scott A. Hepford Justin Fontenot Candi Nobles-James Carol Wilson Adam M. Starr Mohammed Abdelsaid Stanley T. Lewis Jonathan R. T. Lakey 《International journal of molecular sciences》2022,23(3)
Prevalence of type 2 diabetes increased from 2.5% of the US population in 1990 to 10.5% in 2018. This creates a major public health problem, due to increases in long-term complications of diabetes, including neuropathy, retinopathy, nephropathy, skin ulcers, amputations, and atherosclerotic cardiovascular disease. In this review, we evaluated the scientific basis that supports the use of physiologic insulin resensitization. Insulin resistance is the primary cause of type 2 diabetes. Insulin resistance leads to increasing insulin secretion, leading to beta-cell exhaustion or burnout. This triggers a cascade leading to islet cell destruction and the long-term complications of type 2 diabetes. Concurrent with insulin resistance, the regular bursts of insulin from the pancreas become irregular. This has been treated by the precise administration of insulin more physiologically. There is consistent evidence that this treatment modality can reverse the diabetes-associated complications of neuropathy, diabetic ulcers, nephropathy, and retinopathy, and that it lowers HbA1c. In conclusion, physiologic insulin resensitization has a persuasive scientific basis, significant treatment potential, and likely cost benefits. 相似文献
105.
Peter T.Cummings Philippe M.Fauchet Michael Goldfarb Martha W.M.Jones Maithilee Kunda Jonathan B.Perlin Nilanjan Sarkar Keivan G.Stassun Zachary E.Warren Karl E.Zelik 《工程(英文)》2021,7(2):141-143,中插10-中插13
1. Background
The use of engineering tools, design, research, and thinking to create environments and capabilities whereby individuals who are currently under-e... 相似文献
106.
Erica Perreca Franziska Eberl Maricel Valeria Santoro Louwrance Peter Wright Axel Schmidt Jonathan Gershenzon 《International journal of molecular sciences》2022,23(7)
White spruce (Picea glauca) emits monoterpenes that function as defensive signals and weapons after herbivore attack. We assessed the effects of drought and methyl jasmonate (MeJA) treatment, used as a proxy for herbivory, on monoterpenes and other isoprenoids in P. glauca. The emission of monoterpenes was significantly increased after MeJA treatment compared to the control, but drought suppressed the MeJA-induced increase. The composition of the emitted blend was altered strongly by stress, with drought increasing the proportion of oxygenated compounds and MeJA increasing the proportion of induced compounds such as linalool and (E)-β-ocimene. In contrast, no treatment had any significant effect on the levels of stored monoterpenes and diterpenes. Among other MEP pathway-derived isoprenoids, MeJA treatment decreased chlorophyll levels by 40%, but had no effect on carotenoids, while drought stress had no impact on either of these pigment classes. Of the three described spruce genes encoding 1-deoxy-D-xylulose-5-phosphate synthase (DXS) catalyzing the first step of the MEP pathway, the expression of only one, DXS2B, was affected by our treatments, being increased by MeJA and decreased by drought. These findings show the sensitivity of monoterpene emission to biotic and abiotic stress regimes, and the mediation of the response by DXS genes. 相似文献
107.
Daniel S. K. Liu Qi Zhi Clayton Yang Mohammad Asim Jonathan Krell Adam E. Frampton 《International journal of molecular sciences》2022,23(7)
Extracellular vesicles (EVs) are important for intercellular signalling in multi-cellular organisms. However, the role of mature transfer RNAs (tRNAs) and tRNA fragments in EVs has yet to be characterised. This systematic review aimed to identify up-to-date literature on tRNAs present within human EVs and explores their potential clinical significance in health and disease. A comprehensive and systematic literature search was performed, and the study was conducted in accordance with PRISMA guidelines. Electronic databases MEDLINE and EMBASE were searched up until 1 January 2022. From 685 papers, 60 studies were identified for analysis. The majority of papers reviewed focussed on the role of EV tRNAs in cancers (31.7%), with numerous other conditions represented. Blood and cell lines were the most common EV sources, representing 85.9% of protocols used. EV isolation methods included most known methods, precipitation being the most common (49.3%). The proportion of EV tRNAs was highly variable, ranging between 0.04% to >95% depending on tissue source. EV tRNAs are present in a multitude of sources and show promise as disease markers in breast cancer, gastrointestinal cancers, and other diseases. EV tRNA research is an emerging field, with increasing numbers of papers highlighting novel methodologies for tRNA and tRNA fragment discovery. 相似文献
108.
Jonathan Mandel Martina Casari Maria Stepanyan Alexey Martyanov Carsten Deppermann 《International journal of molecular sciences》2022,23(7)
There is accumulating evidence that platelets play roles beyond their traditional functions in thrombosis and hemostasis, e.g., in inflammatory processes, infection and cancer, and that they interact, stimulate and regulate cells of the innate immune system such as neutrophils, monocytes and macrophages. In this review, we will focus on platelet activation in hemostatic and inflammatory processes, as well as platelet interactions with neutrophils and monocytes/macrophages. We take a closer look at the contributions of major platelet receptors GPIb, αIIbβ3, TLT-1, CLEC-2 and Toll-like receptors (TLRs) as well as secretions from platelet granules on platelet–neutrophil aggregate and neutrophil extracellular trap (NET) formation in atherosclerosis, transfusion-related acute lung injury (TRALI) and COVID-19. Further, we will address platelet–monocyte and macrophage interactions during cancer metastasis, infection, sepsis and platelet clearance. 相似文献
109.
Stereolithography (SL) is a rapid prototyping process, which allows one to build complex shapes quickly. Current research investigates the possibilities of using this process to make injection molds. This would allow designers to manufacture and test molds easily and rapidly. One of the main issues with this technique is the effects of its surface on the part. Molds built by SL have high roughness. This gives rise to a high friction force between the part and the mold, and increases the ejection force needed to eject the part from the mold. High ejection forces often lead to damage or breakage of the part and the mold. Research was undertaken on the effects of draft angle and roughness on ejection forces. It was found that increasing the draft angle does not necessary assist the ejection of the part. As the draft angle increases, the roughness and hence the friction force between the part and the mold also increase. There is a trade‐off between draft angle and roughness. A model based on Glanvill's equation was developed to predict ejection force and was consistent with experimental results. 相似文献
110.
Jason Iles Raminta Zmuidinaite Christoph Sadee Anna Gardiner Jonathan Lacey Stephen Harding Jernej Ule Debra Roblett Jonathan Heeney Helen Baxendale Ray K. Iles 《International journal of molecular sciences》2022,23(8)
The immune response to SARS-CoV-2 infection requires antibody recognition of the spike protein. In a study designed to examine the molecular features of anti-spike and anti-nucleocapsid antibodies, patient plasma proteins binding to pre-fusion stabilised complete spike and nucleocapsid proteins were isolated and analysed by matrix-assisted laser desorption ionisation–time of flight (MALDI-ToF) mass spectrometry. Amongst the immunoglobulins, a high affinity for human serum albumin was evident in the anti-spike preparations. Careful mass comparison revealed the preferential capture of advanced glycation end product (AGE) forms of glycated human serum albumin by the pre-fusion spike protein. The ability of bacteria and viruses to surround themselves with serum proteins is a recognised immune evasion and pathogenic process. The preference of SARS-CoV-2 for AGE forms of glycated serum albumin may in part explain the severity and pathology of acute respiratory distress and the bias towards the elderly and those with (pre)diabetic and atherosclerotic/metabolic disease. 相似文献