全文获取类型
收费全文 | 581篇 |
免费 | 53篇 |
国内免费 | 68篇 |
专业分类
电工技术 | 85篇 |
综合类 | 64篇 |
化学工业 | 67篇 |
金属工艺 | 4篇 |
机械仪表 | 12篇 |
建筑科学 | 24篇 |
矿业工程 | 5篇 |
能源动力 | 3篇 |
轻工业 | 20篇 |
水利工程 | 4篇 |
石油天然气 | 15篇 |
武器工业 | 7篇 |
无线电 | 123篇 |
一般工业技术 | 38篇 |
冶金工业 | 49篇 |
原子能技术 | 5篇 |
自动化技术 | 177篇 |
出版年
2024年 | 3篇 |
2023年 | 5篇 |
2022年 | 12篇 |
2021年 | 18篇 |
2020年 | 15篇 |
2019年 | 7篇 |
2018年 | 7篇 |
2017年 | 13篇 |
2016年 | 17篇 |
2015年 | 17篇 |
2014年 | 34篇 |
2013年 | 30篇 |
2012年 | 44篇 |
2011年 | 49篇 |
2010年 | 48篇 |
2009年 | 28篇 |
2008年 | 25篇 |
2007年 | 32篇 |
2006年 | 36篇 |
2005年 | 40篇 |
2004年 | 18篇 |
2003年 | 31篇 |
2002年 | 36篇 |
2001年 | 24篇 |
2000年 | 30篇 |
1999年 | 9篇 |
1998年 | 12篇 |
1997年 | 6篇 |
1996年 | 6篇 |
1995年 | 3篇 |
1994年 | 5篇 |
1993年 | 6篇 |
1992年 | 3篇 |
1991年 | 6篇 |
1990年 | 4篇 |
1989年 | 2篇 |
1987年 | 3篇 |
1985年 | 4篇 |
1984年 | 3篇 |
1983年 | 1篇 |
1982年 | 2篇 |
1980年 | 1篇 |
1979年 | 2篇 |
1978年 | 1篇 |
1976年 | 1篇 |
1965年 | 1篇 |
1961年 | 1篇 |
1958年 | 1篇 |
排序方式: 共有702条查询结果,搜索用时 15 毫秒
81.
为满足深水钻井隔水管系统的需要,采用等强度螺栓连接、高压动态密封、高强度厚壁管体全熔透对接焊接等技术,研制了MT-E50F型深水隔水管终端接头,并进行了8 896 kN载荷试验、静水压试验和连接互换性试验。试验结果表明,MT-E50F型隔水管终端接头满足深水使用要求和载荷工作要求,密封性能可靠。提出了进一步完成MT-E50F型隔水管终端接头深水水下工业性海试、开展隔水管LMRP系统集成研究和试验等建议。该装置的成功开发对海洋钻井隔水管系统国产化具有一定的参考作用。 相似文献
82.
83.
以明胶作为皮胶原模拟物,以甲醇、二碳酸二叔丁酯((Boc)2O)作为封端剂分别封闭明胶的羧基、氨基,并用FT-IR、等电点(PI)和总碳含量(TOC)等对未改性明胶、羧基封闭明胶、氨基封闭明胶分别进行结构和性能表征。结果显示,甲醇、(Boc)2O与明胶反应后分别有酯键、酰胺键生成;羧基封闭的明胶等电点由未改性明胶的4.8上升到6.2,而氨基封闭的明胶等电点则下降到3.6;未改性明胶、羧基封闭明胶、氨基封闭明胶单位体积的总C含量分别是41.48、46.46、48.96 mg/L,羧基封闭明胶和氨基封闭明胶总有机碳含量都高于未改性明胶,表明明胶的羧基、氨基分别被封闭。 相似文献
84.
Maciej Dabrowski Zuzanna Bukowy-Bieryllo Claire L. Jackson Ewa Zietkiewicz 《International journal of molecular sciences》2021,22(9)
Primary ciliary dyskinesia (PCD) is a rare disease with autosomal recessive inheritance, caused mostly by bi-allelic gene mutations that impair motile cilia structure and function. Currently, there are no causal treatments for PCD. In many disease models, translational readthrough of premature termination codons (PTC-readthrough) induced by aminoglycosides has been proposed as an effective way of restoring functional protein expression and reducing disease symptoms. However, variable outcomes of pre-clinical trials and toxicity associated with long-term use of aminoglycosides prompt the search for other compounds that might overcome these problems. Because a high proportion of PCD-causing variants are nonsense mutations, readthrough therapies are an attractive option. We tested a group of chemical compounds with known PTC-readthrough potential (ataluren, azithromycin, tylosin, amlexanox, and the experimental compound TC007), collectively referred to as non-aminoglycosides (NAGs). We investigated their PTC-readthrough efficiency in six PTC mutations found in Polish PCD patients, in the context of cell and cilia health, and in comparison to the previously tested aminoglycosides. The NAGs did not compromise the viability of the primary nasal respiratory epithelial cells, and the ciliary beat frequency was retained, similar to what was observed for gentamicin. In HEK293 cells transfected with six PTC-containing inserts, the tested compounds stimulated PTC-readthrough but with lower efficiency than aminoglycosides. The study allowed us to select compounds with minimal negative impact on cell viability and function but still the potential to induce PTC-readthrough. 相似文献
85.
This article analyzes the different ways to terminate public-private-partnership (PPP) contracts early. It discusses how early terminations should be addressed to mitigate the consequences in terms of attractiveness, bankability, unfairness and litigation. The different ways to compensate private partners are examined. A new methodology for calculating the due compensation is proposed whenever governments voluntarily terminate a PPP contract based on the public interest. We posit that early termination clauses of contracts that comprise fair and reasonable compensations are required to provide meaningful incentives and contestability to acceptable returns on essential public services avoiding political and conflicting issues. 相似文献
86.
Focuses on the termination of psychoanalytic treatment with young children, taking into account the relationship to the parents and its impact on the conduct of treatment, especially at the sensitive ending phase. The author reflects on D. W. Winnicott's (1977) case, "The Piggle," from this perspective. The verbatim notes and comments offer a classic, detailed example of the complex factors impinging upon the conclusion of treating a young child and the wisdom of an outstanding therapist. A 2nd case of a 7-yr-old girl who came to treatment because of a reaction of delayed mourning is also reviewed. The case illustrates the issues involved in the early traumatic loss of a parent, how this loss is reflected within the transference relationship, and the subsequent unfolding of treatment. (PsycINFO Database Record (c) 2011 APA, all rights reserved) 相似文献
87.
88.
由于缺乏合适的去模糊图像质量度量方法,迭代型去模糊算法通常将其迭代次数简单地设置为固定值,无法在执行效率和去模糊质量之间获得最优的平衡点。为此,提出一种粗精检测相结合的迭代终止机制并将其应用到迭代型去模糊算法中以自适应地确定它们最佳的迭代次数。具体地,在每一步迭代过程中利用伪PSNR值细粒度地判断去模糊图像质量是否趋于稳定,另一方面每隔若干步利用从反向卷积残差图像中提取的统计特征值粗粒度准确地判定图像质量是否达到最佳,将两种去模糊图像质量度量方法有机结合以实现一种效率高且准确的迭代终止判定机制。评估结果显示,将所提出的粗精相结合的终止机制应用于NCSR、GSR和ADMM共三种主流去模糊算法后,执行效率可提高50%左右,而去模糊图像质量也得到了最佳保证。实验结果表明,提出的检测机制能够有效地解决各种迭代型去模糊算法因采用固定迭代次数而存在的无益迭代和过迭代问题,非常具有普适性。 相似文献
89.
Han Gyeol Lee Lingfei Wang Liang Si Xiaoyue He Daniel G. Porter Jeong Rae Kim Eun Kyo Ko Jinkwon Kim Sung Min Park Bongju Kim Andrew Thye Shen Wee Alessandro Bombardi Zhicheng Zhong Tae Won Noh 《Advanced materials (Deerfield Beach, Fla.)》2020,32(8):1905815
The metal–insulator transition (MIT) in transition-metal-oxide is fertile ground for exploring intriguing physics and potential device applications. Here, an atomic-scale MIT triggered by surface termination conversion in SrRuO3 ultrathin films is reported. Uniform and effective termination engineering at the SrRuO3(001) surface can be realized via a self-limiting water-leaching process. As the surface termination converts from SrO to RuO2, a highly insulating and nonferromagnetic phase emerges within the topmost SrRuO3 monolayer. Such a spatially confined MIT is corroborated by systematic characterizations on electrical transport, magnetism, and scanning tunneling spectroscopy. Density functional theory calculations and X-ray linear dichroism further suggest that the surface termination conversion breaks the local octahedral symmetry of the crystal field. The resultant modulation in 4d orbital occupancy stabilizes a nonferromagnetic insulating surface state. This work introduces a new paradigm to stimulate and tune exotic functionalities of oxide heterostructures with atomic precision. 相似文献
90.