全文获取类型
收费全文 | 3884篇 |
免费 | 567篇 |
国内免费 | 150篇 |
专业分类
电工技术 | 133篇 |
综合类 | 206篇 |
化学工业 | 690篇 |
金属工艺 | 131篇 |
机械仪表 | 157篇 |
建筑科学 | 445篇 |
矿业工程 | 17篇 |
能源动力 | 55篇 |
轻工业 | 1387篇 |
水利工程 | 17篇 |
石油天然气 | 188篇 |
武器工业 | 12篇 |
无线电 | 284篇 |
一般工业技术 | 346篇 |
冶金工业 | 156篇 |
原子能技术 | 28篇 |
自动化技术 | 349篇 |
出版年
2024年 | 9篇 |
2023年 | 76篇 |
2022年 | 152篇 |
2021年 | 241篇 |
2020年 | 180篇 |
2019年 | 149篇 |
2018年 | 154篇 |
2017年 | 198篇 |
2016年 | 168篇 |
2015年 | 203篇 |
2014年 | 218篇 |
2013年 | 268篇 |
2012年 | 250篇 |
2011年 | 286篇 |
2010年 | 246篇 |
2009年 | 189篇 |
2008年 | 195篇 |
2007年 | 203篇 |
2006年 | 208篇 |
2005年 | 163篇 |
2004年 | 129篇 |
2003年 | 112篇 |
2002年 | 82篇 |
2001年 | 71篇 |
2000年 | 63篇 |
1999年 | 46篇 |
1998年 | 35篇 |
1997年 | 36篇 |
1996年 | 37篇 |
1995年 | 20篇 |
1994年 | 31篇 |
1993年 | 18篇 |
1992年 | 15篇 |
1991年 | 18篇 |
1990年 | 13篇 |
1989年 | 7篇 |
1988年 | 12篇 |
1987年 | 7篇 |
1986年 | 5篇 |
1985年 | 12篇 |
1984年 | 10篇 |
1983年 | 6篇 |
1982年 | 8篇 |
1981年 | 7篇 |
1980年 | 4篇 |
1979年 | 12篇 |
1962年 | 4篇 |
1958年 | 2篇 |
1957年 | 3篇 |
1955年 | 2篇 |
排序方式: 共有4601条查询结果,搜索用时 265 毫秒
121.
以建筑美学作为了解光伏建筑设计的切入点,利用设计学三大构成分析光伏组件的美学特性,进行运用形式美规律分析组件与建筑设计的一些处理手法,以期为涉足光伏建筑领域的设计师提供参考。 相似文献
122.
123.
124.
Development and Validation of an Artificial Mechanical Skin Model for the Study of Interactions between Skin and Microneedles 下载免费PDF全文
Sahan A. Ranamukhaarachchi Thomas Schneider Sarah Lehnert Lisa Sprenger Jonathon R. Campbell Iman Mansoor Jacqueline C. Y. Lai Kimit Rai Jan Dutz Urs O. Häfeli Boris Stoeber 《大分子材料与工程》2016,301(3):306-314
Microneedles are small needle‐like structures that are almost invisible to the naked eye. They have an immense potential to serve as a valuable tool in many medical applications, such as painless vaccination. Microneedles work by breaking through the stratum corneum, the outermost barrier layer of the skin, and providing a direct path for drug delivery into the skin. A lot of research has been presented over the past two decades on the applications of microneedles, yet the fundamental mechanism of how they interact, pressure, and penetrate the skin in its native state is worth examining further. As such, a major difficulty with understanding the mechanism of microneedle–skin interaction is the lack of an artificial mechanical human skin model to use as a standardized substrate. In this research news, the development of an artificial mechanical skin model based on a thorough mechanical study of fresh human and porcine skin samples is presented. The artificial mechanical skin model can be used to study the mechanical interactions between microneedles and skin, but not diffusion of molecules across skin. This model can assist in improving the performance of microneedles by enhancing the reproducibility of microneedle depth insertions for optimal drug delivery and biosensing.
125.
126.
The influence of the use of moulding sand with furan resin, prepared both with fresh sand and reclaimed matrix, on the formation of a flake graphite formation at the surface layer of ductile iron castings has been investigated. A series of experimental heats of ductile iron cast in moulds made of moulding sand characterised by different levels of surface active elements (sulphur, oxygen) were performed. The effect of the wall thickness and the initial temperature of the metal in the mould cavity on the formation of flake graphite in the surface layer of the casting is shown in the paper. Investigations carried out by means of scanning electron microscopy (energy dispersive X-ray spectroscopy and wavelength dispersive X-ray spectroscopy) showed concentration of gradient profiles of surface active elements in the castings surface layer, which are responsible for their quality. Finally, it has been shown that there exists a significant effect of the quality of the sand on the formation of the flake graphite layer and the surface characteristics of ductile iron castings. 相似文献
127.
Laurence Feldmeyer Kristine Heidemeyer Nikhil Yawalkar 《International journal of molecular sciences》2016,17(8)
Acute generalized exanthematous pustulosis (AGEP) is a severe, usually drug-related reaction, characterized by an acute onset of mainly small non-follicular pustules on an erythematous base and spontaneous resolution usually within two weeks. Systemic involvement occurs in about 20% of cases. The course is mostly benign, and only in rare cases complications lead to life-threatening situations. Recent studies highlight the importance of genetic variations in interleukin-36 receptor antagonist gene (IL-36RN) in the pathogenesis of this disease. The physiopathology of AGEP remains unclear, but an involvement of innate and acquired immune cells together with resident cells (keratinocytes), which recruit and activate neutrophils via production of cytokines/chemokines such as IL-17, IL-36, granulocyte-macrophage colony-stimulating factor (GM-CSF), tumor necrosis factor alpha (TNFα) and chemokine (C-X-C motif) ligand 8 (CXCL8)/IL-8, has been postulated. Treatment is based on the removal of the causative drug, supportive care, infection prevention and use of potent topical or systemic steroids. 相似文献
128.
目的:观察复方甘草酸苷对着色紫癜性皮肤病(pigmented purpuric dermatosis,PPD)患者抗菌肽LL-37的表达及其对患者临床预后的影响。方法:选取本院2015年4月到2018年4月间收治的54例PPD患者为研究对象,随机抽签将其分为观察组和对照组,每组27例,另外选取30例正常受试者作为正常组。对照组口服甲泼尼龙片、皮损处涂抹氟芬那酸丁酯软膏进行治疗;观察组在此基础上给予口服复方甘草酸苷片治疗;正常组不做任何治疗处理,1个月后进行观察评价。比较观察组和对照组患者的疗效、不良反应发生率及复发率,比较三组血清中LL-37水平与皮损处LL-37水平以及三组血清TNF-α、IL-6、IL-17炎性因子水平。结果:治疗前,观察组和对照组患者血清LL-37水平、皮损处LL-37水平以及血清TNF-α、IL-6、IL-17水平比较无明显差异(P>0.05),治疗后,两组患者血清LL-37水平、皮损处LL-37水平与血清TNF-α、IL-6、IL-17水平均显著降低(P<0.05),且观察组血清LL-37水平、皮损处LL-37水平与血清TNF-α、IL-6、IL-17水平均明显低于对照组(P<0.05)。观察组治疗有效率为70.37%,显著高于对照组51.85%(P<0.05);观察组不良反应发生率为18.52%,略低于对照组33.33%,但差异无统计学意义(P>0.05);观察组复发率为11.11%,略低于对照组18.52%,但差异无统计学意义(P>0.05)。结论:复方甘草酸苷能够降低PPD患者体内抗菌肽LL-37的表达水平,减轻炎性反应,同时不良反应发生率和复发率更低,疗效及安全性更佳,值得临床推广。 相似文献
129.
130.
针对现有文献对速度趋肤效应影响下的电磁轨道炮电感梯度研究不足的问题,从毕奥-萨伐尔定律出发,提出一种新的电感梯度计算方法。指出文献给出的4种电感梯度计算方法的缺点与不足,将轨道中电流假设为均匀分布于轨道的内表面及上、下表面,采用文中方法与文献给出4种计算方法对电感梯度进行分析,并将其计算值与ANSYS仿真及实验得到的电感梯度值进行对比。结果表明:该方法与文献给出4种计算方法所得计算值的变化趋势较为一致,但方法得到的电感梯度值较为接近,具有形式简单、计算准确的优点。 相似文献