全文获取类型
收费全文 | 41328篇 |
免费 | 2760篇 |
国内免费 | 2020篇 |
专业分类
电工技术 | 884篇 |
技术理论 | 1篇 |
综合类 | 2011篇 |
化学工业 | 14293篇 |
金属工艺 | 8107篇 |
机械仪表 | 1734篇 |
建筑科学 | 1589篇 |
矿业工程 | 836篇 |
能源动力 | 897篇 |
轻工业 | 3529篇 |
水利工程 | 223篇 |
石油天然气 | 1455篇 |
武器工业 | 273篇 |
无线电 | 1305篇 |
一般工业技术 | 6415篇 |
冶金工业 | 1846篇 |
原子能技术 | 249篇 |
自动化技术 | 461篇 |
出版年
2024年 | 233篇 |
2023年 | 768篇 |
2022年 | 1229篇 |
2021年 | 1342篇 |
2020年 | 1184篇 |
2019年 | 1103篇 |
2018年 | 1138篇 |
2017年 | 1372篇 |
2016年 | 1228篇 |
2015年 | 1312篇 |
2014年 | 1953篇 |
2013年 | 2230篇 |
2012年 | 2748篇 |
2011年 | 3151篇 |
2010年 | 2450篇 |
2009年 | 2472篇 |
2008年 | 2016篇 |
2007年 | 2704篇 |
2006年 | 2594篇 |
2005年 | 2234篇 |
2004年 | 1934篇 |
2003年 | 1555篇 |
2002年 | 1351篇 |
2001年 | 1124篇 |
2000年 | 965篇 |
1999年 | 764篇 |
1998年 | 633篇 |
1997年 | 511篇 |
1996年 | 406篇 |
1995年 | 333篇 |
1994年 | 247篇 |
1993年 | 208篇 |
1992年 | 196篇 |
1991年 | 113篇 |
1990年 | 81篇 |
1989年 | 66篇 |
1988年 | 36篇 |
1987年 | 11篇 |
1986年 | 27篇 |
1985年 | 10篇 |
1984年 | 8篇 |
1983年 | 15篇 |
1982年 | 11篇 |
1981年 | 5篇 |
1980年 | 5篇 |
1976年 | 2篇 |
1975年 | 2篇 |
1974年 | 5篇 |
1959年 | 2篇 |
1951年 | 8篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
凝汽器铜管FeSO4镀膜监测系统的开发 总被引:1,自引:0,他引:1
为了减缓凝汽器铜管的腐蚀,通常采用FeSO4造膜保护,而FeSO4膜质量很难控制,作者通过凝汽器铜管FeSO4镀膜成膜工艺,影响因素的深入研究,建立了以电化学响应为特征的镀膜控制系统,选择了相应的传感器,形成以计算机处理为核心的监测系统,应用表明,该系统方便,可靠。 相似文献
52.
针对深孔钻机水刹车传动机构原设计结构中存在的问题进行分析、研究、并对机构进行了改进,满足了钻机绞车的各项性能指标和技术要求。 相似文献
53.
医用聚氯乙烯材料的表面光接枝改性 总被引:6,自引:0,他引:6
研究了在不排氧氛围下 ,紫外光照射 ,以二苯甲酮 (BP)为光引发剂 ,甲基丙烯酸缩水甘油酯(GMA)在医用聚氯乙烯 (PVC)薄膜表面的气相接枝聚合。探讨了反应条件对接枝结果的影响 ,并用正交法指出了影响因素的显著性。用傅立叶红外 (FT- IR)、水接触角作为接枝改性结果的表征。FT- IR谱图表明 GMA已接枝到 PVC膜表面。水接触角由接枝前的 78°下降到 5 4° 相似文献
54.
针对大口径螺旋焊管内涂层涂敷作业时,钢管内残留的涂料挥发份如何清除的问题,介绍了一种自行设计制造的内涂层涂敷挥发份吹除装置。 相似文献
55.
Glass columns (length 50 cm, i.d. 4 cm) containing 900 g of uranium ore waste were subjected to a three-step process: (1) acid drainage generation, (2) neutralization and precipitation treatment and, again, (3) acid drainage generation. In the first acid generation step, lasting about one year, different variables (pyrite addition, inoculation and irrigation solution) were tested by measuring effluent pH, redox potential, total iron and sulphate. Conditions of acid generation were satisfactorily reproduced, reaching stable pH values around 2.0 that were determined mainly by pyrite addition and the type of irrigation solution used (distilled water or ferrous sulphate). The neutralization and precipitation treatment consisted of alternating irrigations of a neutralizing solution (CaO saturated plus NaOH) and a precipitating solution (ferric sulphate saturated). This treatment caused accumulation of basic iron sulphate and iron oxide precipitates according to SEM studies. After this treatment, the barrier effect created by the reaction products was checked, using irrigation solutions similar to the first step. The effluents collected showed higher pH and lower redox potential, total iron and sulphate values than those observed before the treatment, evidencing inhibition of acid drainage generation. 相似文献
56.
旋风分离器结构改进的研究 总被引:3,自引:0,他引:3
根据旋风分离器的工作原理及应用特点 ,分析了影响旋风分离器分离效率的因素及结构存在的问题 ,并提出了改进措施 ,即内管外壁增设螺旋翼片 ,扩散形锥体改为悬挂挡板。通过实验观察 ,改进结构的旋风分离器分离效率比常规旋风分离器高。实践证明 ,对于密度差异较小的非均相物系的分离 ,只要对旋风分离器作适当改进 ,仍能取得令人满意的效果 ,这大大拓宽了旋风分离器的应用领域 相似文献
57.
58.
A Oyane M Kasahara N Ichinose Y Yokoyama M Uchida A Ito 《武汉理工大学学报(材料科学英文版)》2005,20(B12):220-222
A synthetic polymer with a laminin-apatite composite layer on its surface would be useful as a percutaneous device. The preparation of such a composite was attempted in the present study using poly( ethylene terephthalate ) (PET) and polyethylene (PE) as the synthetic polymer. PET and PE plates and those pretreated with an oxygen plasma were alternately dipped in calcium and phosphate ion solutions, and then immersed in a metastable calcium phosphate solution supplemented with laminin ( LCP solution ). The PET and PE plates pretreated with an oxygen plasma formed a uniform and continuous layer of a laminin-apatite composite on their surfaces. In contrast, the PET and PE plates that had not been pretreated with an oxygen plasma did not form a continuous layer of a laminin-apatite composite on their surfaces. The hydrophilic functional groups on the PET and PE surfaces introduced by the plasma treatment were responsible for the successful laminin-apatite coruposite coating. 相似文献
59.
Novel polyurethane insulating coatings were prepared from the reaction of glycerin‐terminated polyurethane prepolymers (GPUPs) and a blocked isocyanate curing agent (BIC). The GPUPs were prepared from the reaction of one equivalent of polycaprolactone polyol (CAPA 210) with an excess amount of 4,4′‐methylene bis(phenyl isocyanate) (MDI) and subsequent reaction of the NCO‐terminated polyurethane with glycerin. The BIC was prepared from the reaction of trimethylol propane (TMP), toluene diisocyanate (TDI) and N‐methylaniline (NMA). The polyols and curing agent were characterized by conventional methods while the curing condition was optimized via gel content measurements. The curing kinetics of the polyurethane coating were investigated and the kinetic parameters derived. The crosslink densities of the samples were determined via the equilibrium swelling method, using the Flory–Rehner equation. The relationships between the crosslink density and the electrical, physical, mechanical and dynamic mechanical properties of the coatings were also studied. Copyright © 2005 Society of Chemical Industry 相似文献
60.