全文获取类型
收费全文 | 98085篇 |
免费 | 20772篇 |
国内免费 | 3717篇 |
专业分类
电工技术 | 5490篇 |
技术理论 | 6篇 |
综合类 | 5483篇 |
化学工业 | 25767篇 |
金属工艺 | 3863篇 |
机械仪表 | 4714篇 |
建筑科学 | 6935篇 |
矿业工程 | 1940篇 |
能源动力 | 2701篇 |
轻工业 | 11749篇 |
水利工程 | 1781篇 |
石油天然气 | 3032篇 |
武器工业 | 650篇 |
无线电 | 13475篇 |
一般工业技术 | 17767篇 |
冶金工业 | 3357篇 |
原子能技术 | 696篇 |
自动化技术 | 13168篇 |
出版年
2024年 | 205篇 |
2023年 | 1018篇 |
2022年 | 1768篇 |
2021年 | 2791篇 |
2020年 | 3444篇 |
2019年 | 4718篇 |
2018年 | 4881篇 |
2017年 | 5391篇 |
2016年 | 5617篇 |
2015年 | 6455篇 |
2014年 | 7112篇 |
2013年 | 8702篇 |
2012年 | 6858篇 |
2011年 | 6797篇 |
2010年 | 6773篇 |
2009年 | 6256篇 |
2008年 | 6075篇 |
2007年 | 5559篇 |
2006年 | 5115篇 |
2005年 | 4131篇 |
2004年 | 3527篇 |
2003年 | 3443篇 |
2002年 | 3819篇 |
2001年 | 3326篇 |
2000年 | 2649篇 |
1999年 | 1698篇 |
1998年 | 872篇 |
1997年 | 760篇 |
1996年 | 668篇 |
1995年 | 536篇 |
1994年 | 377篇 |
1993年 | 270篇 |
1992年 | 236篇 |
1991年 | 174篇 |
1990年 | 133篇 |
1989年 | 119篇 |
1988年 | 84篇 |
1987年 | 52篇 |
1986年 | 46篇 |
1985年 | 15篇 |
1984年 | 14篇 |
1983年 | 9篇 |
1982年 | 17篇 |
1981年 | 16篇 |
1980年 | 30篇 |
1979年 | 7篇 |
1978年 | 2篇 |
1959年 | 3篇 |
1951年 | 2篇 |
1890年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 212 毫秒
11.
Karolina Storesund Francine Amon Anne Steen‐Hansen Shayesteh Haghighatpanah Ida Larsson 《火与材料》2021,45(1):181-190
The aim of this exploratory study has been to investigate the fire properties and environmental aspects of different upholstery material combinations, mainly for domestic applications. An analysis of the sustainability and circularity of selected textiles, along with lifecycle assessment, is used to qualitatively evaluate materials from an environmental perspective. The cone calorimeter was the primary tool used to screen 20 different material combinations from a fire performance perspective. It was found that textile covers of conventional fibres such as wool, cotton and polyester, can be improved by blending them with fire resistant speciality fibres. A new three‐dimensional web structure has been examined as an alternative padding material, showing preliminary promising fire properties with regard to ignition time, heat release rates and smoke production. 相似文献
12.
Wenjie Liu Jianmin Liu Shu Xing Xiaobin Li Liwen Han Kechun Liu Tao Wei Mingyang Zhou 《European Journal of Lipid Science and Technology》2021,123(6):2000276
In this study, the anti-atherosclerotic properties of three marine phospholipids (MPLs) extracts from fishery by-products including codfish roe, squid gonad, and shrimp head are verified. Their effects on key factors involved in atherosclerosis are examined and compared to explore whether the differences in their constitutions lead to the differences in the function. All three MPLs dampen oxidation of low- density lipoproteins (LDL) in vitro. Treating RAW264.7 macrophages and HUVECs endothelial cells with each MPLs ranging 10–100 µg mL−1 does not decrease cell viability, yet ox-LDL caused cytotoxicity of both cells are alleviated by 50 or 100 µg mL−1 MPLs treatment. In addition, the three MPLs reduce ox-LDL induced macrophage foam-like transition, mainly through inhibition of lipid uptake. Of the three MPLs, the one from squid gonad exhibits the best effect. On the other hand, all three MPLs modulate inflammatory responses, equally, by inhibiting the adhesion of monocytes to endothelial cells, and decreasing secretion of pro-inflammatory cytokines IL-6 and MCP-1. Using a high-cholesterol diet induced zebrafish model, it is found that all three MPLs, especially the one from squid gonad, alleviates cholesterol accumulation in early plaques, and decreases total cholesterol as well as lipid peroxide in vivo. Practical Applications: As a way of making the best of the increasingly scarce marine resources, valuable lipid components can be recovered from by-products and wastes from the fishery industry. Here, we tested the anti-atherosclerotic effects and the mechanisms of three MPLs extracted from codfish roe, squid gonad, and shrimp head. Our study provides further evidence that marine phospholipids extracted from fishery by-products could protect against atherosclerosis, and helps to elucidate the structure-function relationship of MPLs. 相似文献
13.
14.
针对采煤机滚筒进行煤岩的截割过程中,容易引起振动作用,不利于采煤机稳定工作的问题,基于滚筒的进给速度及旋转速度,建立滚筒与煤岩的动力学模型,分析不同的进给速度及旋转速度对采煤机动态响应的影响,为选择合理的参数提供依据. 相似文献
15.
16.
Fluorescence‐Activated Cell Sorters: Standing Surface Acoustic Wave (SSAW)‐Based Fluorescence‐Activated Cell Sorter (Small 40/2018) 下载免费PDF全文
17.
18.
Polymer‐grafted inorganic particles (PGIPs) are attractive building blocks for numerous chemical and material applications. Surface‐initiated controlled radical polymerization (SI‐CRP) is the most feasible method to fabricate PGIPs. However, a conventional in‐batch reaction still suffers from several disadvantages, including time‐consuming purification processes, low grafting efficiency, and possible gelation problems. Herein, a facile method is demonstrated to synthesize block copolymer–grafted inorganic particles, that is, poly(poly(ethylene glycol) methyl ether methacrylate) (PPEGMEMA)‐b‐poly(N‐isopropylacrylamide) (PNIPAM)–grafted silica micro‐particles using continuous flow chemistry in an environmentally friendly aqueous media. Immobilizing the chain transfer agent and subsequent SI‐CRP can be accomplished sequentially in a continuous flow system, avoiding multi‐step purification processes in between. The chain length (MW) of the grafted polymers is tunable by adjusting the flow time or monomer concentration, and the narrower molar mass dispersity (Ð < 1.4) of the grafted polymers reveals the uniform polymer chains on the particles. Moreover, compared with the in‐batch reaction at the same condition, the continuous system also suppresses possible gelation problems. 相似文献
19.
20.