全文获取类型
收费全文 | 13661篇 |
免费 | 753篇 |
国内免费 | 431篇 |
专业分类
电工技术 | 170篇 |
综合类 | 568篇 |
化学工业 | 3012篇 |
金属工艺 | 4008篇 |
机械仪表 | 1249篇 |
建筑科学 | 320篇 |
矿业工程 | 351篇 |
能源动力 | 283篇 |
轻工业 | 1506篇 |
水利工程 | 47篇 |
石油天然气 | 110篇 |
武器工业 | 110篇 |
无线电 | 215篇 |
一般工业技术 | 1895篇 |
冶金工业 | 804篇 |
原子能技术 | 29篇 |
自动化技术 | 168篇 |
出版年
2024年 | 25篇 |
2023年 | 150篇 |
2022年 | 197篇 |
2021年 | 339篇 |
2020年 | 318篇 |
2019年 | 227篇 |
2018年 | 254篇 |
2017年 | 383篇 |
2016年 | 431篇 |
2015年 | 424篇 |
2014年 | 695篇 |
2013年 | 675篇 |
2012年 | 905篇 |
2011年 | 1087篇 |
2010年 | 764篇 |
2009年 | 838篇 |
2008年 | 723篇 |
2007年 | 953篇 |
2006年 | 847篇 |
2005年 | 705篇 |
2004年 | 609篇 |
2003年 | 606篇 |
2002年 | 539篇 |
2001年 | 457篇 |
2000年 | 420篇 |
1999年 | 303篇 |
1998年 | 219篇 |
1997年 | 187篇 |
1996年 | 124篇 |
1995年 | 116篇 |
1994年 | 80篇 |
1993年 | 45篇 |
1992年 | 61篇 |
1991年 | 32篇 |
1990年 | 28篇 |
1989年 | 28篇 |
1988年 | 28篇 |
1987年 | 10篇 |
1986年 | 2篇 |
1985年 | 2篇 |
1983年 | 1篇 |
1982年 | 3篇 |
1966年 | 2篇 |
1962年 | 1篇 |
1954年 | 1篇 |
1951年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
51.
Yuki Tanaka Takumi Sako Tatsuhiro Hiraoka Misaki Yamaguchi Masayuki Yamaguchi 《应用聚合物科学杂志》2020,137(46):49516
The structure and rheological properties of binary blends of polycarbonate (PC) and polystyrene (PS) were investigated using various PS samples with different molecular weights, namely PS1k (Mw = 1,000), PS53k (Mw = 53,000), and PS240k (Mw = 240,000). The blends with PS53k and PS240k show phase-separated structures, whereas the blend with PS1k is miscible. The shear viscosity decreases greatly on addition of PS53k and PS240k, especially at high shear rates, which would be a great advantage at processing operations. Because the nonlinear response occurs in the small strain region for multilayered films of PC and PS240k, the origin of the significant viscosity drop for the phase-separated system is interfacial slippage at the phase boundary. 相似文献
52.
《中国生物制品学杂志》2020,(2):213-215,221
氢氧化铝佐剂是使用最为广泛的疫苗佐剂,在其使用过程中,疫苗抗原表位、缓冲体系及添加剂,在一定程度上会对氢氧化铝吸附疫苗的免疫效果造成影响。对氢氧化铝佐剂实行严格的质量控制,对确保佐剂效果及疫苗质量均具有非常重要的意义。本文主要对氢氧化铝佐剂在疫苗中的应用及研究现状作一综述。 相似文献
53.
To minimize the structure distortion and potential de-bonding in adhesive bonding of dissimilar materials (e.g., metals and polymeric composites), a two-component (2 K) low temperature cure modified adhesive consisting of 93.5 wt% commercial Henkel 5089 adhesive, 2.5 wt% N-(2-Hydroxyethyl) ethylenediamine (AEEA) and 4.0 wt% 2-ethyl-4-methylimidazole (2,4-EMI) was formulated. Experimental results showed that the use of the modified adhesive lowered the curing temperature from recommended 177 °C (for 20 min) for Henkel 5089 to 100 °C (for 20 min) or 120 °C (for 10 min) for AA6061-AA6061 joint, and 120 °C (for 20 min) or 130 °C (for 10 min) for AA6061-Cf/PA6 (Nylon 6) and Cf/PA6-Cf/PA6 joints, respectively, due to the faster curing reaction caused by the combined addition of AEEA and 2,4-EMI. It took 5, 3, and 2 days to cure the adhesive-bonded AA6061-AA6061, AA6061-Cf/PA6, and Cf/PA6-Cf/PA6 joints made with the modified adhesive and cured at ambient temperature, respectively. In addition, the modified adhesive had sound working life (5 h) at ambient temperature. The static strengths of all adhesive-bonded AA6061-AA6061, AA6061-Cf/PA6, and Cf/PA6-Cf/PA6 joints with the modified adhesive were hardly affected by thermal exposure cycle (i.e., exposure to 82 °C for 30 min). These results indicated that the modified adhesive possesses the promising characteristics for joining of similar and dissimilar materials. 相似文献
54.
55.
《Advanced Powder Technology》2020,31(4):1720-1727
A new concept of powder atomization based on the venturi phenomenon is presented in the current work. In the proposed method, the working gas speeds-up while flowing into the venturi nozzle. Under the low static pressure developing at the narrow part of the venturi, liquid metal is sucked and mixed perfectly with the gas. By controlling the operating parameters, metal powder of different sizes and shapes can be produced. Carbon dioxide and pure aluminum were mixed in the nozzle and the effect of different operating gas pressures on the produced particle size and shape were thoroughly investigated. Most of the particles were found to average to almost 150 μm, however, even sub-micron aluminum particles were produced at low mass fractions. With the increase of the gas pressure from 0.5 bar to 4 bar, finer aluminum particles are produced. One of the most attractive features of the proposed method is the low gas pressure required to cause melt atomization, which in certain cases may be up to 30 times lower compared to current industrial atomization methods. 相似文献
56.
Z. Zhu H. Peng Y. Liu H. Tu J. Wang X. Su 《Materialwissenschaft und Werkstofftechnik》2020,51(7):992-1001
Single-, two-, and three-stage homogenization treatments of heat-resistant alloy 2618 were conducted in this study. Results reveal a low melting point Al2CuMg phase and high melting point Al2Cu phase in the as-cast aluminum alloy 2618. After single-stage homogenization at 495 °C for 10 h, the Al2CuMg phase dissolves completely, but the Al2Cu phase cannot be completely dissolved even once the homogenization time is prolonged to 18 h. After the alloy 2618 are homogenized using two stages: 495 °C for 10 h and 520 °C for 8 h, a portion of the Al2Cu phase remains in the alloy. The Al2Cu phase remains undissolved even after prolonged time. After the two-stage homogenization treatment at 495 °C for 10 h and 540 °C for 5 h, the high melting point Al2Cu phase completely dissolves but overburn occurs. After the alloy 2618 are homogenized using three stages at 495 °C for 10 h, 520 °C for 5 h, and 540 °C for 3 h, the Al2Cu phase completely dissolves and no overburn is detected. The three-stage homogenization treatment is an effective method for dissolving the high melting point Al2Cu phase in the alloy 2618 and increasing their overburn temperature and solid solution temperature. 相似文献
58.
Jian-hua XIANG Chao ZHOU Chun-liang ZHANG Gui-yun LIU Cong-gui CHEN Wei ZHOU 《中国有色金属学会会刊》2018,28(7):1404-1412
A theoretical model of phase change heat sink was established in terms of thermal resistance network. The influence of different parameters on the thermal resistance was analyzed and the crucial impact factors were determined. Subsequently, the forming methods including ploughing–extrusion and stamping method of boiling enhancement structure at evaporation surface were investigated, upon which three-dimensional microgroove structure was fabricated to improve the efficiency of evaporation. Moreover, the crucial parameters related to the fabrication of miniaturized phase change heat sink were optimized. The heat transfer performance of the heat sink was tested. Results show that the developed phase change heat sink has excellent heat transfer performance and is suitable for high power LED applications. 相似文献
59.
针对某5A06铝合金鞍型横梁,设计了等温挤压近净成形试验。通过Deform有限元分析研究了鞍型横梁等温挤压过程中金属流动规律和缺陷产生原因,并进行了毛坯尺寸和热挤压件图的优化。设计了鞍型横梁等温挤压近净成形模具,可实现在普通压力机上加热管加热方式升温、成形后多顶杆同步脱模功能。通过等温挤压近净成形方法制备了长为580 mm、最薄壁厚为4 mm、筋高为8 mm、筋宽为6 mm的薄壁复杂多筋鞍型横梁,该构件90%以上部位尺寸精度可达到±0. 3 mm,其余部位尺寸精度可达±0. 5 mm,抗拉强度达340 MPa,伸长率约为25%。对等温挤压件装配部位进行少量机加,可获得3种不同尺寸的鞍型横梁。 相似文献
60.
随着经济的不断发展,国民也越来越注重食品的品质和安全。目前中小食品企业在国内得到越来越多的关注和重视。榨汁机被广泛应用在食品行业,发挥着巨大的作用。汁液获取的三种方法包括机械榨取、理化获取、酶法提取。理化和酶法在使用过程中因会产生物理化学反应,导致其他副作用从而在使用上有极大局限性,机械榨汁由于其无副作用而被企业广泛应用在蔬菜、水果上。基于此,研究了螺旋式连续榨汁机,其核心思想是以压缩体积为基础的一种机械榨取机。首先介绍了榨汁机的设计思路;其次介绍了工作原理;最后展示了榨汁机的机械组成。与传统的榨汁机相比,该方法设计的榨汁机是通过变螺距变径螺杆,从而充分地挤出新鲜果汁,具有十分重要的实际研究意义。 相似文献