全文获取类型
收费全文 | 185篇 |
免费 | 25篇 |
国内免费 | 30篇 |
专业分类
系统科学 | 20篇 |
丛书文集 | 1篇 |
理论与方法论 | 1篇 |
现状及发展 | 42篇 |
研究方法 | 16篇 |
综合类 | 154篇 |
自然研究 | 6篇 |
出版年
2022年 | 3篇 |
2021年 | 6篇 |
2020年 | 7篇 |
2019年 | 5篇 |
2018年 | 9篇 |
2017年 | 10篇 |
2016年 | 9篇 |
2015年 | 6篇 |
2014年 | 7篇 |
2013年 | 14篇 |
2012年 | 18篇 |
2011年 | 19篇 |
2010年 | 5篇 |
2009年 | 8篇 |
2008年 | 9篇 |
2007年 | 7篇 |
2006年 | 15篇 |
2005年 | 10篇 |
2004年 | 7篇 |
2003年 | 12篇 |
2002年 | 6篇 |
2001年 | 3篇 |
2000年 | 5篇 |
1999年 | 1篇 |
1997年 | 1篇 |
1996年 | 4篇 |
1994年 | 1篇 |
1993年 | 2篇 |
1990年 | 3篇 |
1989年 | 4篇 |
1984年 | 3篇 |
1983年 | 1篇 |
1982年 | 1篇 |
1980年 | 3篇 |
1976年 | 4篇 |
1975年 | 1篇 |
1971年 | 3篇 |
1969年 | 2篇 |
1968年 | 2篇 |
1966年 | 1篇 |
1965年 | 1篇 |
1964年 | 1篇 |
1961年 | 1篇 |
排序方式: 共有240条查询结果,搜索用时 46 毫秒
121.
纳米技术是当前最感兴趣的课题,本书重点介绍以分子为基础在小系统中研究凝聚态物质,为理解纳米技术提供必要的基础知识。 相似文献
122.
AbdurRashid GhulamMustafa 《中国科学技术大学学报》2003,33(5):547-554
采用带限制算子的傅立叶拟谱方法近似求解了Burgers方程,分别证明了它的(Burgers方程)一般化的稳定性和收敛性,并获得了数值结果. 相似文献
123.
Gebhardt T Whitney PG Zaid A Mackay LK Brooks AG Heath WR Carbone FR Mueller SN 《Nature》2011,477(7363):216-219
Infections localized to peripheral tissues such as the skin result in the priming of T-cell responses that act to control pathogens. Activated T cells undergo migrational imprinting within the draining lymph nodes, resulting in memory T cells that provide local and systemic protection. Combinations of migrating and resident memory T cells have been implicated in long-term peripheral immunity, especially at the surfaces that form pathogen entry points into the body. However, T-cell immunity consists of separate CD4(+) helper T cells and CD8(+) killer T cells, with distinct effector and memory programming requirements. Whether these subsets also differ in their ability to form a migrating pool involved in peripheral immunosurveillance or a separate resident population responsible for local infection control has not been explored. Here, using mice, we show key differences in the migration and tissue localization of memory CD4(+) and CD8(+) T cells following infection of the skin by herpes simplex virus. On resolution of infection, the skin contained two distinct virus-specific memory subsets; a slow-moving population of sequestered CD8(+) T cells that were resident in the epidermis and confined largely to the original site of infection, and a dynamic population of CD4(+) T cells that trafficked rapidly through the dermis as part of a wider recirculation pattern. Unique homing-molecule expression by recirculating CD4(+) T effector-memory cells mirrored their preferential skin-migratory capacity. Overall, these results identify a complexity in memory T-cell migration, illuminating previously unappreciated differences between the CD4(+) and CD8(+) subsets. 相似文献
124.
Yusa K Rashid ST Strick-Marchand H Varela I Liu PQ Paschon DE Miranda E Ordóñez A Hannan NR Rouhani FJ Darche S Alexander G Marciniak SJ Fusaki N Hasegawa M Holmes MC Di Santo JP Lomas DA Bradley A Vallier L 《Nature》2011,478(7369):391-394
Human induced pluripotent stem cells (iPSCs) represent a unique opportunity for regenerative medicine because they offer the prospect of generating unlimited quantities of cells for autologous transplantation, with potential application in treatments for a broad range of disorders. However, the use of human iPSCs in the context of genetically inherited human disease will require the correction of disease-causing mutations in a manner that is fully compatible with clinical applications. The methods currently available, such as homologous recombination, lack the necessary efficiency and also leave residual sequences in the targeted genome. Therefore, the development of new approaches to edit the mammalian genome is a prerequisite to delivering the clinical promise of human iPSCs. Here we show that a combination of zinc finger nucleases (ZFNs) and piggyBac technology in human iPSCs can achieve biallelic correction of a point mutation (Glu342Lys) in the α(1)-antitrypsin (A1AT, also known as SERPINA1) gene that is responsible for α(1)-antitrypsin deficiency. Genetic correction of human iPSCs restored the structure and function of A1AT in subsequently derived liver cells in vitro and in vivo. This approach is significantly more efficient than any other gene-targeting technology that is currently available and crucially prevents contamination of the host genome with residual non-human sequences. Our results provide the first proof of principle, to our knowledge, for the potential of combining human iPSCs with genetic correction to generate clinically relevant cells for autologous cell-based therapies. 相似文献
125.
Zahra Amirsardari Akram Dourani Mohamad Ali Amirifar Nooredin Ghadiri Massoom 《矿物冶金与材料学报》2021,28(7):1233-1239
To discuss the potential role of iridium (Ir) nanoparticles loaded under atmospheric and high pressures, we prepared a series of catalysts with the same active phase but different contents of 10wt%, 20wt%, and 30wt% on gamma-alumina for decomposition of hydrazine. Under atmospheric pressure, the performance of the catalyst was better when 30wt% of the Ir nanoparticles was used with chelating agent that had greater selectivity of approximately 27%. The increase in the reaction rate from 175 to 220 h?1 at higher Ir loading (30wt%) was due to a good dispersion of high-number active phases rather than an agglomeration surface. As a satisfactory result of this investigation at high pressure, Ir catalysts with different weight percentages showed the same stability against crushing and activity with a characteristic velocity of approximately 1300 m/s. 相似文献
126.
The paper examines the propagation direction and velocity of largescale traveling ionospheric disturbances (LSTIDs) during extreme geomagnetic storms in the 23rd solar cycle (e.g., October 2003 and No-vember 2003 storms) using GPS observations. In the analysis, the time delay between the vertical total electron content (VTEC) structures at Scott Base, McMurdo, Davis and Casey GPS stations and the distance between these stations were the main parameters in the determination of LSTIDs propagation speed and di... 相似文献
127.
Preparation,characterization, and antibacterial activity of γ-irradiated silver nanoparticles in aqueous gelatin
下载免费PDF全文
![点击此处可从《矿物冶金与材料学报》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Majid Darroudi Mansor B. Ahmad Mohammad Hakimi Reza Zamiri Ali Khorsand Zak Hasan Ali Hosseini Mohsen Zargar 《矿物冶金与材料学报》2013,20(4):403-409
Colloidal silver nanoparticles (Ag-NPs) were obtained through γ-irradiation of aqueous solutions containing AgNO3 and gelatin as a silver source and stabilizer, respectively. The absorbed dose of γ-irradiation influences the particle diameter of the Ag-NPs, as evidenced from surface plasmon resonance (SPR) and transmission electron microscopy (TEM) images. When the γ-irradiation dose was increased (from 2 to 50 kGy), the mean particle size was decreased continuously as a result of γ-induced Ag-NPs fragmentation. The antibacterial properties of the Ag-NPs were tested against Methicillinresistant Staphylococcus aureus (MRSA) (Gram-positive) and Pseudomonas aeruginosa (P.a) (Gram-negative) bacteria. This approach reveals that the γ-irradiation-mediated method is a promising simple route for synthesizing highly stable Ag-NPs in aqueous solutions with good antibacterial properties for different applications. 相似文献
128.
Processing of nanostructured metallic matrix composites by a modified accumulative roll bonding method with structural and mechanical considerations
下载免费PDF全文
![点击此处可从《矿物冶金与材料学报》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Particulate reinforced metallic matrix composites have attracted considerable attention due to their lightweight, high strength, high specific modulus, and good wear resistance. Al/B4C composite strips were produced in this work by a modified accumulative roll bonding process where the strips were rotated 90° around the normal direction between successive passes. Transmission electron microscopy and X-ray diffraction analyses reveal the development of nanostructures in the Al matrix after seven passes. It is found that the B4C reinforcement distribution in the matrix is improved by progression of the process. Additionally, the tensile yield strength and elongation of the processed materials are increased with the increase of passes. 相似文献
129.
130.