全文获取类型
收费全文 | 6086篇 |
免费 | 540篇 |
国内免费 | 7篇 |
专业分类
电工技术 | 27篇 |
综合类 | 5篇 |
化学工业 | 1432篇 |
金属工艺 | 81篇 |
机械仪表 | 120篇 |
建筑科学 | 235篇 |
矿业工程 | 6篇 |
能源动力 | 119篇 |
轻工业 | 1293篇 |
水利工程 | 76篇 |
石油天然气 | 26篇 |
无线电 | 239篇 |
一般工业技术 | 1020篇 |
冶金工业 | 1212篇 |
原子能技术 | 17篇 |
自动化技术 | 725篇 |
出版年
2024年 | 17篇 |
2023年 | 79篇 |
2022年 | 65篇 |
2021年 | 343篇 |
2020年 | 172篇 |
2019年 | 191篇 |
2018年 | 282篇 |
2017年 | 260篇 |
2016年 | 265篇 |
2015年 | 251篇 |
2014年 | 246篇 |
2013年 | 453篇 |
2012年 | 348篇 |
2011年 | 454篇 |
2010年 | 295篇 |
2009年 | 287篇 |
2008年 | 274篇 |
2007年 | 281篇 |
2006年 | 169篇 |
2005年 | 144篇 |
2004年 | 133篇 |
2003年 | 103篇 |
2002年 | 112篇 |
2001年 | 65篇 |
2000年 | 64篇 |
1999年 | 77篇 |
1998年 | 321篇 |
1997年 | 234篇 |
1996年 | 140篇 |
1995年 | 86篇 |
1994年 | 54篇 |
1993年 | 66篇 |
1992年 | 25篇 |
1991年 | 12篇 |
1990年 | 16篇 |
1989年 | 24篇 |
1988年 | 25篇 |
1987年 | 22篇 |
1986年 | 18篇 |
1985年 | 16篇 |
1984年 | 14篇 |
1983年 | 13篇 |
1982年 | 12篇 |
1981年 | 11篇 |
1980年 | 11篇 |
1978年 | 4篇 |
1977年 | 16篇 |
1976年 | 29篇 |
1975年 | 4篇 |
1973年 | 7篇 |
排序方式: 共有6633条查询结果,搜索用时 78 毫秒
1.
Journal of Chemical Ecology - Biocontrol agents such as parasitic wasps use long-range volatiles and host-associated cues from lower trophic levels to find their hosts. However, this chemical... 相似文献
2.
Esperanza González-Redondo 《建筑学研究前沿(英文版)》2022,11(2):255-277
The constructive analysis of Madrid's old timber-framed collective courtyard buildings, whether demolished, preserved intact, or enlarged, has achieved the dating of relevant case studies. New parameters established in this study set a chronology based on front sector original projects: old (1737–1788), pre-modern (1788–1847) and modern (1847–1892). The on-site inspection and archival research point to ongoing misleading construction in the historic Southern area. Some modern corralas erected on top of pre-existing buildings confirm the initial hypothesis. First dimensioning rules for new façades and the stability required in old ones before adding new storeys, maintaining the original masonry or double-layered system, are discovered. Undated buildings suggest their possible origin a la malicia and a later transformation into transitional corralas. Finally, an analysis of the demolished courtyards narrows down the dating and points to new conjectures in some preserved by showing their uneven layout, old features, and structural discordances in each sector. 相似文献
3.
4.
Towards a Better Prediction of Cell Settling on Nanostructure Arrays—Simple Means to Complicated Ends 下载免费PDF全文
Nina Buch‐Månson Sara Bonde Jessica Bolinsson Trine Berthing Jesper Nygård Karen L. Martinez 《Advanced functional materials》2015,25(21):3246-3255
Vertical arrays of nanostructures (NSs) are emerging as promising platforms for probing and manipulating live mammalian cells. The broad range of applications requires different types of interfaces, but cell settling on NS arrays is not yet fully controlled and understood. Cells are both seen to deform completely into NS arrays and to stay suspended like tiny fakirs, which have hitherto been explained with differences in NS spacing or density. Here, a better understanding of this phenomenon is provided by using a model that takes into account the extreme membrane deformation needed for a cell to settle into a NS array. It is shown that, in addition to the NS density, cell settling depends strongly on the dimensions of the single NS, and that the settling can be predicted for a given NS array geometry. The predictive power of the model is confirmed by experiments and good agreement with cases from the literature. Furthermore, the influence of cell‐related parameters is evaluated theoretically and a generic method of tuning cell settling through surface coating is demonstrated experimentally. These findings allow a more rational design of NS arrays for the numerous exciting biological applications where the mode of cell settling is crucial. 相似文献
5.
6.
7.
D. Kherifi H. Belhouchet S. Ramesh K.Y. Sara Lee A. Kenzour S. Djoualah M.K.G. Abbas Y.H. Wong S. Ramesh 《Ceramics International》2021,47(12):16483-16490
In this work, the sintering behaviour of fluorapatite (FAp)–silicate composites prepared by mixing variable amounts of natural quartz (2.5 wt% to 20 wt%) and FAp was studied. The composites were pressureless sintered in air at temperatures from 1000 °C to 1350 °C. The effects of temperatures on the densification, phase formation, chemical bonding and Vickers hardness of the composites were evaluated. All the samples exhibited mixed phase, comprising FAp and francolite as the major constituents along with some minor phases of cristobalite, wollastonite, dicalcium silicate and/or whitlockite dependent on the quartz content and sintering temperature. The composite containing 2.5 wt% quartz exhibited the best sintering properties. The highest bulk density of 3 g/cm3 and a Vickers hardness of >4.2 GPa were obtained for the 2.5 wt% quartz–FAp composite when sintered at 1100 °C. The addition of quartz was found to alter the microstructure of the composites, where it exhibited a rod-like morphology when sintered at 1000 °C and a regular rounded grain structure when sintered at 1350 °C. A wetted grain surface was observed for composites containing high quartz content and was believed to be associated with a transient liquid phase sintering. 相似文献
8.
9.
10.
Alessandro Lucidi Danilo Buca Carlo Ronsini Sara Tinari Giuseppina Bologna Davide Buca Martina Leombroni Marco Liberati Francesco DAntonio Giovanni Scambia Paola Lanuti Marco Petrillo 《International journal of molecular sciences》2020,21(22)
Extracellular vesicles (EVs) are a heterogeneous group of cell-derived submicron vesicles released under physiological or pathological conditions. EVs mediate the cellular crosstalk, thus contributing to defining the tumor microenvironment, including in epithelial ovarian cancer (EOC). The available literature investigating the role of EVs in EOC has been reviewed following PRISMA guidelines, focusing on the role of EVs in early disease diagnosis, metastatic spread, and the development of chemoresistance in EOC. Data were identified from searches of Medline, Current Contents, PubMed, and from references in relevant articles from 2010 to 1 April 2020. The research yielded 194 results. Of these, a total of 36 papers, 9 reviews, and 27 original types of research were retained and analyzed. The literature findings demonstrate that a panel of EV-derived circulating miRNAs may be useful for early diagnosis of EOC. Furthermore, it appears clear that EVs are involved in mediating two crucial processes for metastatic and chemoresistance development: the epithelial–mesenchymal transition, and tumor escape from the immune system response. Further studies, more focused on in vivo evidence, are urgently needed to clarify the role of EV assessment in the clinical management of EOC patients. 相似文献