全文获取类型
收费全文 | 14047篇 |
免费 | 590篇 |
国内免费 | 343篇 |
专业分类
电工技术 | 148篇 |
技术理论 | 5篇 |
综合类 | 2734篇 |
化学工业 | 1586篇 |
金属工艺 | 349篇 |
机械仪表 | 687篇 |
建筑科学 | 2896篇 |
矿业工程 | 182篇 |
能源动力 | 261篇 |
轻工业 | 2233篇 |
水利工程 | 115篇 |
石油天然气 | 517篇 |
武器工业 | 41篇 |
无线电 | 229篇 |
一般工业技术 | 1249篇 |
冶金工业 | 591篇 |
原子能技术 | 286篇 |
自动化技术 | 871篇 |
出版年
2024年 | 56篇 |
2023年 | 132篇 |
2022年 | 250篇 |
2021年 | 356篇 |
2020年 | 337篇 |
2019年 | 288篇 |
2018年 | 217篇 |
2017年 | 279篇 |
2016年 | 244篇 |
2015年 | 349篇 |
2014年 | 985篇 |
2013年 | 773篇 |
2012年 | 997篇 |
2011年 | 1047篇 |
2010年 | 951篇 |
2009年 | 986篇 |
2008年 | 861篇 |
2007年 | 995篇 |
2006年 | 979篇 |
2005年 | 753篇 |
2004年 | 647篇 |
2003年 | 500篇 |
2002年 | 457篇 |
2001年 | 324篇 |
2000年 | 276篇 |
1999年 | 191篇 |
1998年 | 139篇 |
1997年 | 107篇 |
1996年 | 67篇 |
1995年 | 71篇 |
1994年 | 55篇 |
1993年 | 44篇 |
1992年 | 48篇 |
1991年 | 42篇 |
1990年 | 33篇 |
1989年 | 29篇 |
1988年 | 18篇 |
1987年 | 15篇 |
1986年 | 16篇 |
1985年 | 12篇 |
1984年 | 6篇 |
1983年 | 7篇 |
1982年 | 5篇 |
1973年 | 4篇 |
1972年 | 3篇 |
1961年 | 3篇 |
1960年 | 3篇 |
1959年 | 3篇 |
1957年 | 2篇 |
1955年 | 3篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
Effects of different carbon sources and C/N values on nonvolatile taste components of Pleurotus eryngii 下载免费PDF全文
Wen Li Xiaobei Li Yan Yang Feng Zhou Yanfang Liu Shuai Zhou Hailong Yu 《International Journal of Food Science & Technology》2015,50(11):2360-2366
Pleurotus eryngii, the second largest industrial cultivation mushroom in China, is usually cultivated on substrates mainly consisting of sawdust and corncob. In this study, experiments were performed to determine the effects of different carbon sources and C/N values on nonvolatile taste components of P. eryngii. The effects of different carbon sources on nonvolatile taste components levels revealed that sawdust was beneficial to high levels of crude protein, amino acids, 5′‐nucleotides and equivalent umami concentration, while corncob was beneficial to high contents of carbohydrate, polysaccharides and trehalose. At the similar C/N values, relatively higher sawdust content was beneficial to umami amino acid production, while relatively higher corncob content was beneficial to high contents of carbohydrate, polysaccharides and mannitol. Higher C/N value was beneficial to high levels of crude protein, amino acids, 5′‐nucleotides and equivalent umami concentration, while lower C/N value was beneficial to high contents of carbohydrate, polysaccharides and trehalose. These results provided information for P. eryngii fruit body industrial cultivation to obtain specific nonvolatile taste components with high levels. 相似文献
2.
Andrés Mario Zervigón 《History of Photography》2019,43(2):130-143
For decades now, Douglas Crimp’s landmark 1980 essay ‘The Photographic Activity of Postmodernism’ has shaped our understanding of modernism’s aftermath, at least as it unfolded in North America and Western Europe. Less remembered, however, is the degree to which the procedures of disjunction, copying, appropriation, and outright theft that he highlighted were epitomised not just by contemporary photography, but by photomontage in particular. This article recovers the debates that led critics such as Crimp, Abigail Solomon-Godeau, Christopher Phillips, Benjamin Buchloh and others to turn to photomontage as one of their principal objects of concern in what became known as the postmodern critique of photography. Why was montage tasked to perform this critical function, particularly by people around the journal October who had not otherwise devoted the balance of their writing to photography’s history? The article suggests that these men and women, along with the contemporary artists they foregrounded, manifested what Mary Anne Doane has called a ‘desire for signification’, a reaction in the late 1970s against the mute theatricality of minimalist and conceptual art. Photomontage reintroduced representation to contemporary art and to the canon of art history. But unlike the reemerging illusionism in painting that also manifested this desire, montage guarded against an uncomplicated realism by highlighting and critiquing operations of representation in a manner that painting no longer could. 相似文献
3.
《Ceramics International》2021,47(21):30051-30060
Hydroxyapatite (HA) is a highly regarded synthetic bone graft material. Porous HA ceramics blocks are used to substitute harvested natural bone grafts. Being similar to bone mineral, HA material integrates with the host bone through surface osteointegration and slowly resorb along with the natural bone remodeling process. The blocks in use currently have random and tortuous pore structures. The present work explores the usefulness of cage-like HA ceramic design with end-to-end open pores, with the help of in vitro cell culture methods. Such a structure, on implantation, will take up the blood factors and cells and host the bone remodeling process inside the bulk of the cage, leading to early healing. In the study, HA samples with aligned through-pores were prepared and explored in vitro, with a focus on how the pores host the cells inside and to what level the cells maintain their activity. Human osteoblast-like cells (HOS) were used, at different seeding and culturing approaches. Cell seeding was done through (i) conventional large volume cell suspension, (ii) a confined mini chamber with a limited volume of cell suspension, and (iii) placing a concentrated drop of cell suspension directly on top of the scaffold. The third approach gave the best cell adhesion and proliferation, and hence used for further explorations. A dynamic culture system was designed in-house by bifurcating the cell culture wells using vertical inserts, holding the samples horizontally with their ends open to both sides, and making the media flow across using a rocker platform. The HOS cell adhesion, viability and proliferation were tested in the HA cages, in static and dynamic culture conditions, with conventional porous ceramics as the control. The cell infiltration was deeper and the cell viability over a period of 7 days was significantly higher in dynamic culture conditions in the test samples. 相似文献
4.
对AP1000压水堆核电站安全壳贯穿件的非径向管板焊接接头结构特点进行了介绍,并分析其超声检测工艺的重点和难点。通过建立统一的缺陷定位坐标系并结合被检构件的几何特点进行综合分析,推导得出了h值(缺陷回波最高点距套管外壁的距离)的计算方法。为超声检测对这类焊接接头缺陷的准确识别和定位提供了行之有效的方法,为解决这类焊接接头的超声检测技术受限区提供了行之有效的措施。 相似文献
5.
6.
通过对大直径平底负压容器平底板的设计计算,平底板计算厚度很厚。通过分析,提出了对平底板采取加强措施,从而减薄平底板计算厚度的方法。该容器在实际生产过程中性能可靠、稳定,对类似设备设计具有借鉴意义。 相似文献
7.
《Planning》2019,(2)
2017年,美国心脏病学会和美国心脏协会提出将高血压诊断标准降为130/80 mm Hg (1 mm Hg=0. 133 kPa),这与其他指南有所不同。降压治疗的核心目标在于靶器官的保护,近年来降压治疗与脑小血管病预防的相关问题日益受到临床重视。目前研究结果表明,降压治疗对腔隙性卒中患者的二级预防以及白质病变进展的预防可能有一定积极意义,但确切的降压目标值并未确定。血压与临床结局可能呈现J型关系,血压过低或过高可能均有害,而取得最大获益的降压目标有待进一步探索。 相似文献
8.
9.
10.