全文获取类型
收费全文 | 5175篇 |
免费 | 237篇 |
国内免费 | 73篇 |
专业分类
电工技术 | 170篇 |
综合类 | 54篇 |
化学工业 | 839篇 |
金属工艺 | 112篇 |
机械仪表 | 152篇 |
建筑科学 | 99篇 |
矿业工程 | 19篇 |
能源动力 | 141篇 |
轻工业 | 207篇 |
水利工程 | 31篇 |
石油天然气 | 31篇 |
武器工业 | 8篇 |
无线电 | 813篇 |
一般工业技术 | 676篇 |
冶金工业 | 1559篇 |
原子能技术 | 29篇 |
自动化技术 | 545篇 |
出版年
2024年 | 11篇 |
2023年 | 36篇 |
2022年 | 103篇 |
2021年 | 129篇 |
2020年 | 79篇 |
2019年 | 66篇 |
2018年 | 87篇 |
2017年 | 93篇 |
2016年 | 95篇 |
2015年 | 114篇 |
2014年 | 177篇 |
2013年 | 325篇 |
2012年 | 262篇 |
2011年 | 266篇 |
2010年 | 215篇 |
2009年 | 202篇 |
2008年 | 205篇 |
2007年 | 195篇 |
2006年 | 185篇 |
2005年 | 110篇 |
2004年 | 106篇 |
2003年 | 109篇 |
2002年 | 81篇 |
2001年 | 62篇 |
2000年 | 65篇 |
1999年 | 109篇 |
1998年 | 533篇 |
1997年 | 314篇 |
1996年 | 227篇 |
1995年 | 128篇 |
1994年 | 137篇 |
1993年 | 126篇 |
1992年 | 53篇 |
1991年 | 47篇 |
1990年 | 47篇 |
1989年 | 51篇 |
1988年 | 31篇 |
1987年 | 24篇 |
1986年 | 18篇 |
1985年 | 22篇 |
1984年 | 19篇 |
1983年 | 8篇 |
1982年 | 15篇 |
1981年 | 17篇 |
1980年 | 13篇 |
1978年 | 12篇 |
1977年 | 35篇 |
1976年 | 77篇 |
1975年 | 17篇 |
1973年 | 5篇 |
排序方式: 共有5485条查询结果,搜索用时 15 毫秒
991.
Ou SL Kuo PC Ma SH Shen CL Tsai TL Chen SC Chiang DY Lee CT 《Journal of nanoscience and nanotechnology》2011,11(12):11138-11141
In this study, the (GeSbSn)(100-x0Co(x) films (x = 0-13.3) were deposited on natural oxidized silicon wafer and glass substrate by dc magnetron co-sputtering of GeSbSn and Co targets. The ZnS-SiO2 films were used as protective layers. The thicknesses of the (GeSbSn)(100-x)Co(x) films and protective layer were 100 nm and 30 nm, respectively. We investigated the effects of Co addition on the thermal property, crystallization kinetics, and crystallization mechanism of the GeSbSn recording film. The crystallization temperatures of (GeSbSn)(100-x)Co(x) films were decreased with Co content. It was found that the activation energy of the (GeSbSn)(100-x)Co(x) films will decrease from 1.53 eV to 0.55 eV as Co content increased from 0 at.% to 13.3 at.%. 相似文献
992.
Chang H Kao MJ Peng CH Kuo CG Huang KD 《Journal of nanoscience and nanotechnology》2011,11(8):7491-7494
This study applies the thermoelectric grains of Sb2Te3 on conductive glass to evaporate Sb2Te3 thin films by the electron beam evaporation method. Through experimental tests with different evaporation process parameters and film annealing conditions, thin films with better Seebeck coefficient, resistivity (p) and power fact (PF) can be obtained. Experimental results show that when thin films are annealed, their defects can be decreased accordingly, and carrier mobility can be enhanced to further elevate the conductivity of thin films. When the substrate temperature is set at 200 degrees C to fabricate Sb2Te3 thin films by the evaporation process and by annealing at 220 degrees C for 60 minutes, the Seebeck coefficient of Sb2Te3 thin films increase from 87.6 microV/K to 177.7 microV/K; resistivity falls from 6.21 m ohms-cm to 2.53 m ohms-cm and PF can achieve the maximum value of 1.24 10(-3) W/K2 m. Finally, this study attempts to add indium (In) to Sb2Te3 thin films. Indium has been successfully fabricated In3SbTe, thin films. This study also analyzes the effects of In on the thermoelectric properties of In3SbTe2 thin films. 相似文献
993.
Kao MJ Chang H Kuo CG Huang KD Chen YL 《Journal of nanoscience and nanotechnology》2011,11(8):7459-7462
This study deals with the fabrication of three different morphologies of TiO2 nanoparticles to fabricate two-layer photoelectrode thin film for dye-sensitized solar cells (DSSC). The four different TiO2 morphologies are titania nanotubes (Tnt), TiO2 nanoparticles (H220), TiO2 nanoparticle (SP) and commercial DP-25 nanoparticles (P-25). To prepare the thin films of the photoelectrodes, the first layer is coated by H220 TiO2 nanoparticles, and the second is coated by 3 kinds of materials optimally proportionally mixed - P25, SP and Tnt. The photoelectric conversion efficiency of DSSCs with photoelectrodes fabricated using H220 reached 6.31%. Finally, the TiO2 nanaomaterials with four different morphologies were used to prepare a two layer photoelectrode with the structure of H220/P25-Tnt-SP which was combined with a Pt counter electrode to assemble DSSCs. These DSSCs had photoelectric conversion efficiencies of as high as 7.47%. 相似文献
994.
995.
Shih‐Jen Cheng Huang‐Jen Chiu Yu‐Kang Lo Shu‐Wei Kuo Kuo‐Kuang Jen Kuo‐Sheng Fu Gwo‐Huei You Kun‐Feng Chen Chien‐Min Kao 《International Journal of Circuit Theory and Applications》2014,42(6):584-604
In this paper, a contact‐less power charger for robot applications is studied and developed. Contact‐less charging can be achieved by a separable transformer design. The transformer primary core is in the charger unit, and the secondary core is in the robots. The transformer air‐gap is equal to the distance between these two parts. By theoretical analysis, software simulations, and circuit implementation, the relationship among the transformer's coupling coefficient, the core geometry, and gap are formulated. In addition, a high‐efficiency circuit topology for the studied contact‐less charger is fulfilled. It is anticipated that the research results of this paper can contribute to the development of the contact‐less charging techniques for robot systems. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
996.
Design and implementation of a high‐efficiency bidirectional DC‐DC Converter for DC micro‐grid system applications
下载免费PDF全文
![点击此处可从《International Journal of Circuit Theory and Applications》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Huang‐Jen Chiu Yu‐Kang Lo Shu‐Wei Kuo Shih‐Jen Cheng Feng‐Tsuen Lin 《International Journal of Circuit Theory and Applications》2014,42(11):1139-1153
This paper studies the design and implementation of a non‐isolated dual‐half‐bridge bidirectional DC‐DC converter for DC micro‐grid system applications. High efficiency can be achieved under wide‐range load variations by the zero‐voltage‐switching features and an adaptive phase‐shift control method. A three‐stage charging scheme is designed to meet the fast‐charging demand and prolong the lifetime of LiFePO4 batteries. A digital‐signal‐processing control IC is used to realize the power flow control, DC‐bus voltage regulation, and battery charging/ discharging of the studied bidirectional DC‐DC converter. Finally, a 10 kW prototype converter with Enhanced Controller Area Network communication function is built and tested for micro‐grid system applications. A light‐load efficiency over 96% and a rated‐load efficiency over 98% can be achieved. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
997.
Kuo-Ti Peng Jiun-Liang Chen Liang-Tseng Kuo Pei-An Yu Wei-Hsiu Hsu Chiang-Wen Lee Pey-Jium Chang Tsung-Yu Huang 《International journal of molecular sciences》2021,22(13)
Periprosthetic joint infections (PJIs) caused by Staphylococcus aureus infection are difficult to treat due to antibiotic resistance. It is known that the biofilms from methicillin-resistant S. aureus (MRSA) promote expansion of myeloid-derived suppressor cells (MDSCs) to suppress T-cell proliferation and benefit bacterial infections. This study finds that GMI, a fungal immunomodulatory peptide isolated from Ganoderma microsporum, suppresses MDSC expansion to promote the proliferation of cytotoxic T cells. The enhancement is likely attributed to increased expression of IL-6 and TNF-α and reduction in ROS expression. Similar beneficial effects of GMI on the suppression of MDSC expansion and IL-6 expression are also observed in the whole blood and reduces the accumulation of MDSCs in the infected bone region in a mouse PJI infection model. This study shows that GMI is potentially useful for treating S. aureus-induced PJIs. 相似文献
998.
Shu-Yu Cheng Nan-Fu Chen Zhi-Hong Wen Zhi-Kang Yao Kuan-Hao Tsui Hsiao-Mei Kuo Wu-Fu Chen 《International journal of molecular sciences》2021,22(13)
Glioblastoma multiforme (GBM) is a malignant primary brain tumor. The 5-year relative survival rate of patients with GBM remains <30% on average despite aggressive treatments, and secondary therapy fails in 90% of patients. In chemotherapeutic failure, detoxification proteins are crucial to the activity of chemotherapy drugs. Usually, glutathione S-transferase (GST) superfamily members act as detoxification enzymes by activating xenobiotic metabolites through conjugation with glutathione in healthy cells. However, some overexpressed GSTs not only increase GST activity but also trigger chemotherapy resistance and tumorigenesis-related signaling transductions. Whether GSTM3 is involved in GBM chemoresistance remains unclear. In the current study, we found that T98G, a GBM cell line with pre-existing temozolomide (TMZ) resistance, has high glycolysis and GSTM3 expression. GSTM3 knockdown in T98G decreased glycolysis ability through lactate dehydrogenase A activity reduction. Moreover, it increased TMZ toxicity and decreased invasion ability. Furthermore, we provide next-generation sequencing–based identification of significantly changed messenger RNAs of T98G cells with GSTM3 knockdown for further research. GSTM3 was downregulated in intrinsic TMZ-resistant T98G with a change in the expression levels of some essential glycolysis-related genes. Thus, GSTM3 was associated with glycolysis in chemotherapeutic resistance in T98G cells. Our findings provide new insight into the GSTM3 mechanism in recurring GBM. 相似文献
999.
Yi-Cheng Chen Yu-Chi Chou Yu-Tung Hsieh Pin-Yu Kuo Mei-Lin Yang Hao-Earn Chong Chao-Liang Wu Ai-Li Shiau Chrong-Reen Wang 《International journal of molecular sciences》2021,22(13)
Diffuse alveolar hemorrhage (DAH) in systemic lupus erythematosus (SLE) is associated with significant mortality, requiring a thorough understanding of its complex mechanisms to develop novel therapeutics for disease control. Activated p53-dependent apoptosis with dysregulated long non-coding RNA (lncRNA) expression is involved in the SLE pathogenesis and correlated with clinical activity. We examined the expression of apoptosis-related p53-dependent lncRNA, including H19, HOTAIR and lincRNA-p21 in SLE-associated DAH patients. Increased lincRNA-p21 levels were detected in circulating mononuclear cells, mainly in CD4+ and CD14+ cells. Higher expression of p53, lincRNA-p21 and cell apoptosis was identified in lung tissues. Lentivirus-based short hairpin RNA (shRNA)-transduced stable transfectants were created for examining the targeting efficacy in lncRNA. Under pristane stimulation, alveolar epithelial cells had increased p53, lincRNA-p21 and downstream Bax levels with elevated apoptotic ratios. After pristane injection, C57/BL6 mice developed DAH with increased pulmonary expression of p53, lincRNA-p21 and cell apoptosis. Intra-pulmonary delivery of shRNA targeting lincRNA-p21 reduced hemorrhage frequencies and improved anemia status through decreasing Bax expression and cell apoptosis. Our findings demonstrate increased p53-dependent lncRNA expression with accelerated cell apoptosis in the lungs of SLE-associated DAH patients, and show the therapeutic potential of targeting intra-pulmonary lncRNA expression in a pristane-induced model of DAH. 相似文献
1000.
目的建立离子色谱-双波长紫外检测法同时测定水中碘酸盐和碘离子的分析方法。方法水样过0.22μm滤膜后直接进样测定,水中碘酸根和碘离子通过离子色谱柱分离,紫外检测器分别在200nm和226nm处检测。结果碘酸根和碘离子在0.01~1.00mg/L浓度范围内线性良好,相关系数r分别为0.99953和0.99950,检出限为0.004和0.005mg/L,相对标准偏差(relative standard deviations,RSDs)为2.8%和2.7%(n=8)。低(0.05mg/L)、中(0.10mg/L)、高(0.50mg/L)3个浓度IO_3~-和I~-加标回收率范围为94%~106%和92%~102%,精密度为1.04%~4.82%和0.75%~4.47%。结论本方法操作简单、准确度高、精密度好、线性范围宽,适用于水中碘酸盐和碘离子的测定。 相似文献