全文获取类型
收费全文 | 3986篇 |
免费 | 224篇 |
国内免费 | 71篇 |
专业分类
电工技术 | 171篇 |
综合类 | 54篇 |
化学工业 | 834篇 |
金属工艺 | 110篇 |
机械仪表 | 152篇 |
建筑科学 | 94篇 |
矿业工程 | 19篇 |
能源动力 | 141篇 |
轻工业 | 204篇 |
水利工程 | 31篇 |
石油天然气 | 31篇 |
武器工业 | 8篇 |
无线电 | 814篇 |
一般工业技术 | 674篇 |
冶金工业 | 374篇 |
原子能技术 | 29篇 |
自动化技术 | 541篇 |
出版年
2024年 | 11篇 |
2023年 | 36篇 |
2022年 | 103篇 |
2021年 | 130篇 |
2020年 | 78篇 |
2019年 | 66篇 |
2018年 | 87篇 |
2017年 | 92篇 |
2016年 | 95篇 |
2015年 | 114篇 |
2014年 | 177篇 |
2013年 | 323篇 |
2012年 | 263篇 |
2011年 | 265篇 |
2010年 | 214篇 |
2009年 | 202篇 |
2008年 | 204篇 |
2007年 | 196篇 |
2006年 | 185篇 |
2005年 | 108篇 |
2004年 | 106篇 |
2003年 | 105篇 |
2002年 | 81篇 |
2001年 | 62篇 |
2000年 | 65篇 |
1999年 | 68篇 |
1998年 | 152篇 |
1997年 | 108篇 |
1996年 | 83篇 |
1995年 | 53篇 |
1994年 | 68篇 |
1993年 | 55篇 |
1992年 | 49篇 |
1991年 | 32篇 |
1990年 | 36篇 |
1989年 | 35篇 |
1988年 | 21篇 |
1987年 | 19篇 |
1986年 | 13篇 |
1985年 | 18篇 |
1984年 | 17篇 |
1983年 | 7篇 |
1982年 | 8篇 |
1981年 | 9篇 |
1980年 | 6篇 |
1978年 | 8篇 |
1977年 | 7篇 |
1976年 | 9篇 |
1975年 | 7篇 |
1973年 | 5篇 |
排序方式: 共有4281条查询结果,搜索用时 15 毫秒
101.
Chih-Yu Kuo Ting-Yu Liu Andri Hardiansyah Chia-Fen Lee Man-Sheng Wang Wen-Yen Chiu 《Nanoscale research letters》2014,9(1):520
In the present work, we prepare thermo- and pH-sensitive polymer-based nanoparticles incorporating with magnetic iron oxide as the remote-controlled, stimuli-response nanocarriers. Well-defined, dual functional tri-block copolymer poly[(acrylic acid)-block-(N-isopropylacrylamide)-block-(acrylic acid)], was synthesized via reversible addition-fragmentation chain-transfer (RAFT) polymerization with S,S′-bis(α,α′-dimethyl-α″-acetic acid)trithiocarbonate (CMP) as a chain transfer agent (CTA). With the aid of using 3-aminopropyltriethoxysilane, the surface-modified iron oxides, Fe3O4-NH2, was then attached on the surface of self-assembled tri-block copolymer micelles via 1-[3-(dimethylamino)propyl]-3-ethylcarbodiimide hydrochloride/N-hydroxysuccinamide (EDC/NHS) crosslinking method in order to furnish not only the magnetic resources for remote control but also the structure maintenance for spherical morphology of our nanocarriers. The nanocarrier was characterized by transmission electron microscope (TEM), Fourier transform infrared spectroscopy (FT-IR), and ultraviolet–visible (UV/Vis) spectral analysis. Rhodamine 6G (R6G), as the modeling drugs, was encapsulated into the magnetic nanocarriers by a simple swelling method for fluorescence-labeling and controlled release monitoring. Biocompatibility of the nanocarriers was studied via 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, which revealed that neither the pristine nanocarrier nor the R6G-loaded nanocarriers were cytotoxic to the normal fibroblast cells (L-929 cells). The in vitro stimuli-triggered release measurement showed that the intelligent nanocarriers were highly sensitive to the change of pH value and temperature rising by the high-frequency magnetic field (HFMF) treatment, which provided the significant potential to apply this technology to biomedical therapy by stimuli-responsive controlled release. 相似文献
102.
Da-Ren Hang Sk Emdadul Islam Krishna Hari Sharma Shiao-Wei Kuo Cheng-Zu Zhang Jun-Jie Wang 《Nanoscale research letters》2014,9(1):632
Vertically aligned ZnO nanorods (NRs) on aluminum-doped zinc oxide (AZO) substrates were fabricated by a single-step aqueous solution method at low temperature. In order to optimize optical quality, the effects of annealing on optical and structural properties were investigated by scanning electron microscopy, X-ray diffraction, photoluminescence (PL), and Raman spectroscopy. We found that the annealing temperature strongly affects both the near-band-edge (NBE) and visible (defect-related) emissions. The best characteristics have been obtained by employing annealing at 400°C in air for 2 h, bringing about a sharp and intense NBE emission. The defect-related recombinations were also suppressed effectively. However, the enhancement decreases with higher annealing temperature and prolonged annealing. PL study indicates that the NBE emission is dominated by radiative recombination associated with hydrogen donors. Thus, the enhancement of NBE is due to the activation of radiative recombinations associated with hydrogen donors. On the other hand, the reduction of visible emission is mainly attributed to the annihilation of OH groups. Our results provide insight to comprehend annealing effects and an effective way to improve optical properties of low-temperature-grown ZnO NRs for future facile device applications. 相似文献
103.
The effect of dispersion processes on complex permittivity and microwave absorption in 2?18 GHz ranges is presented for nanocomposites loaded with different amounts of carbon nanotubes (CNTs) ranging from 1 to 5 wt %. The ultrasonic sonication (US) method and the three‐roll mill (TRM) method were performed for the manufacturing of the CNT/epoxy absorbers with different dispersing levels. Microscopic observations revealed that the CNT agglomerates were reduced after the TRM process, and individual CNTs were uniformly dispersed in the epoxy resin. For the same weight content of CNT fillers, the percentage increase of between US and TRM samples varies from 35.5% to 101.7% while the corresponding increment of (dielectric loss) varies from 79.6% to 248.8%. A minimum reflection loss for the US sample with 2 wt % CNTs is only ?7.8 dB at 11.3 GHz while the corresponding TRM sample is greatly improved to reach ?37.4 dB at 7.76 GHz for the same matching thickness of 3 mm. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40963. 相似文献
104.
Chien-Chang Lu Hsing-Chun Kuo Feng-Sheng Wang Ming-Huey Jou Ko-Chao Lee Jiin-Haur Chuang 《International journal of molecular sciences》2015,16(1):159-177
Toll-like receptors (TLRs) not only form an important part of the innate immune system but also serve to activate the adaptive immune system in response to cancer. Real-time PCR; immunohistochemical stain and Western blotting analyses were performed to clarify molecular alterations in colorectal cancer (CRC) patients. We identified Toll-like receptor 1 (TLR1), TLR2, TLR4 and TLR8 gene expression levels and downstream gene, i.e., interleukin-6 (IL-6), IL-8, interferon-α (IFN-α) and myeloid differentiation primary-response protein-88 (MyD88), expression levels in CRC patients and in cancer cell lines. CRC tissues have higher TLR1, TLR2, TLR4, TLR8, IL-6 and IL-8 gene expression levels than do the normal colon mucosa (p < 0.05). TLR2 expression varied in different cell types (mucosa and lymphocytes). There was no difference in the MyD88 and IFN-α gene expression levels between cancerous and normal colon mucosa. CRC patients had higher levels of IL-6 (p = 0.002) and IL-8 (p = 0.038) expression than healthy volunteers did; and higher IL-6 and IL-8 expression was also found to signify a higher risk of recurrence. CL075 (3M002) treatments can reduce the production of IL-8 in different cancer cell lines. The signaling pathway of TLRs in cancer tissue is different from that in normal cells; and is MyD88-independent. Higher expression levels of TLR1, TLR2, TLR 4 and TLR 8 mRNA were related to upregulation inflammatory cytokines IL-6 and IL-8 gene expression in tissue and to the upregulation of IL-6 in blood. The concentration of IL-6 in serum can be used as an indicator of the possibility of CRC recurrence. Treatment with 3M002 can reduce IL-6 production in vitro and may prevent CRC recurrence. Our findings provide evidence that TLR1, TLR2, TLR4 and TLR8 gene expression induce downstream IL-6 and IL-8 gene expression; detection of these expression levels can serve as a CRC marker. 相似文献
105.
Jih-Jung Chen Chieh-Kai Yang Yueh-Hsiung Kuo Tsong-Long Hwang Wen-Lung Kuo Yun-Ping Lim Ping-Jyun Sung Tsung-Hsien Chang Ming-Jen Cheng 《International journal of molecular sciences》2015,16(5):9719-9731
Three new coumarin derivatives, 8-formylalloxanthoxyletin (1), avicennone (2), and (Z)-avicennone (3), have been isolated from the stem bark of Zanthoxylum avicennae (Z. avicennae), together with 15 known compounds (4–18). The structures of these new compounds were determined through spectroscopic and MS analyses. Compounds 1, 4, 9, 12, and 15 exhibited inhibition (half maximal inhibitory concentration (IC50) values ≤7.65 µg/mL) of superoxide anion generation by human neutrophils in response to formyl-l-methionyl-l-leucyl-l-phenylalanine/cytochalasin B (fMLP/CB). Compounds 1, 2, 4, 8 and 9 inhibited fMLP/CB-induced elastase release with IC50 values ≤8.17 µg/mL. This investigation reveals bioactive isolates (especially 1, 2, 4, 8, 9, 12 and 15) could be further developed as potential candidates for the treatment or prevention of various inflammatory diseases. 相似文献
106.
Dong-Hau Kuo Waltraud M. Kriven Thomas J. Mackin 《Journal of the American Ceramic Society》1997,80(12):2987-2996
Fiber pushout tests were used to quantify the effects of fiber coating thickness on the mechanical properties of two model composite systems: a monazite-coated (LaPO4 -coated) alumina (Al2 O3 ) fiber in an Al2 O3 matrix and a LaPO4 -coated yttrium aluminum garnet (YAG) fiber in an Al2 O3 matrix. Interface properties were quantified using the Liang and Hutchinson (LH) pushout model and mechanistically rationalized by considering the change in residual thermal stresses with changes in the coating thickness. Measures of the pure Mode II interfacial fracture energy, the coefficient of friction, and a radial clamping pressure are extracted by fitting the LH equations to the experimental results. Using the approach that has been developed herein, a methodology is available for measuring the interfacial properties, predicting the effect of coating thickness, and selecting the coating thickness to 相似文献
107.
采用自制端羧基超分散剂(ECH)改性剑麻纤维(SF)/聚丙烯(PP)复合材料,探讨了ECH的使用对SF/PP复合材料的力学性能、热力学性能和结晶性能的影响,并采用扫描电镜(SEM)观察复合材料的冲击断面形貌。结果表明,经ECH改性后的SF/PP复合材料的冲击强度、弯曲强度分别比未改性的复合材料提高了67.3%和21.0%,复合材料的热稳定性、PP相的结晶速率和结晶度有所提高,但晶态结构仍是典型的α晶型,ECH的加入使得复合材料的储能模量提高,损耗因子降低。 相似文献
108.
JY Yeh MS Coumar HY Shiao TJ Lin YC Lee HC Hung S Ko FM Kuo MY Fang YL Huang JT Hsu TK Yeh SR Shih YS Chao JT Horng HP Hsieh 《ChemMedChem》2012,7(9):1546-1550
From a high-throughput screening (HTS) hit with inhibitory activity against virus-induced cytophathic in the low micromolar range, we have developed a potent anti-influenza lead through careful optimization without compromising the drug-like properties of the compound. An orally bioavailable compound was identified as a lead agent with nanomolar activity against influenza, representing a 140-fold improvement over the initial hit. 相似文献
109.
Chia-Hung Kuo Hsin-Hung Chen Jiann-Hwa Chen Yung-Chuan Liu Chwen-Jen Shieh 《International journal of molecular sciences》2012,13(9):11694-11704
Wax esters are long-chain esters that have been widely applied in premium lubricants, parting agents, antifoaming agents and cosmetics. In this study, the biocatalytic preparation of a specific wax ester, cetyl octanoate, is performed in n-hexane using two commercial immobilized lipases, i.e., Lipozyme® RMIM (Rhizomucor miehei) and Novozym® 435 (Candida antarctica). Response surface methodology (RSM) and 5-level-4-factor central composite rotatable design (CCRD) are employed to evaluate the effects of reaction time (1–5 h), reaction temperature (45–65 °C), substrate molar ratio (1–3:1), and enzyme amount (10%–50%) on the yield of cetyl octanoate. Using RSM to optimize the reaction, the maximum yields reached 94% and 98% using Lipozyme® RMIM and Novozym® 435, respectively. The optimum conditions for synthesis of cetyl octanoate by both lipases are established and compared. Novozym® 435 proves to be a more efficient biocatalyst than Lipozyme® RMIM. 相似文献
110.
Three‐dimensional particle size segregation structures of binary mixtures of six different size ratios (SR = 1.42–3.37) in a rotating drum are studied. The formation of two smaller particle satellites around the central smaller‐particle rich band after the band formation core‐thickening mechanism is reported for the first time. The binary mixtures of six SRs show three satellite shapes, including the small bump shape, the axe shape, and the hemisphere shape. Except for the binary mixture of SR = 2.01 with the axe satellite shape, the satellite size increases with the increasing of the SR value at the same bed depth. The degrees of mixing of binary mixtures of six different SRs at different bed depths are analyzed using the Lacey mixing index. The degree of mixing at the bed surface and close to the drum cylindrical wall can be explained by the drift‐diffusional model of Savage (1993). © 2011 American Institute of Chemical Engineers AIChE J, 2012 相似文献