全文获取类型
收费全文 | 61895篇 |
免费 | 6946篇 |
国内免费 | 3847篇 |
专业分类
电工技术 | 5170篇 |
技术理论 | 2篇 |
综合类 | 4968篇 |
化学工业 | 8927篇 |
金属工艺 | 3515篇 |
机械仪表 | 4408篇 |
建筑科学 | 5171篇 |
矿业工程 | 2026篇 |
能源动力 | 1719篇 |
轻工业 | 4816篇 |
水利工程 | 1454篇 |
石油天然气 | 2668篇 |
武器工业 | 734篇 |
无线电 | 7842篇 |
一般工业技术 | 6591篇 |
冶金工业 | 2367篇 |
原子能技术 | 809篇 |
自动化技术 | 9501篇 |
出版年
2024年 | 302篇 |
2023年 | 1088篇 |
2022年 | 2306篇 |
2021年 | 3169篇 |
2020年 | 2385篇 |
2019年 | 1852篇 |
2018年 | 2146篇 |
2017年 | 2288篇 |
2016年 | 2034篇 |
2015年 | 3198篇 |
2014年 | 3856篇 |
2013年 | 4244篇 |
2012年 | 4866篇 |
2011年 | 5137篇 |
2010年 | 4658篇 |
2009年 | 4127篇 |
2008年 | 3972篇 |
2007年 | 3702篇 |
2006年 | 3363篇 |
2005年 | 2742篇 |
2004年 | 2007篇 |
2003年 | 1665篇 |
2002年 | 1694篇 |
2001年 | 1439篇 |
2000年 | 1075篇 |
1999年 | 817篇 |
1998年 | 541篇 |
1997年 | 417篇 |
1996年 | 359篇 |
1995年 | 290篇 |
1994年 | 210篇 |
1993年 | 188篇 |
1992年 | 147篇 |
1991年 | 79篇 |
1990年 | 70篇 |
1989年 | 79篇 |
1988年 | 50篇 |
1987年 | 25篇 |
1986年 | 11篇 |
1985年 | 13篇 |
1984年 | 8篇 |
1983年 | 6篇 |
1982年 | 8篇 |
1981年 | 13篇 |
1980年 | 18篇 |
1979年 | 7篇 |
1977年 | 1篇 |
1966年 | 1篇 |
1959年 | 10篇 |
1951年 | 5篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
101.
XIAO Chang-jiang SUN Ming ZHOU Hong-yan LIU Sui-xin LONG Kai-chao HE Fei LI Tong 《中南工业大学学报(英文版)》2005,12(Z1)
Objective Study on the effect of NF-κB in ox-LDL injured HUVEC-304 and the intervention with the serum of Tongmai Decoction. Methods Tongmai Decoction herbage-contained serum was made by the serum pharmacology methods, then the HUVEC-304 cells were divided into 5 groups and incubated for 24 h: 1) normal group;2) fetal calf serum group; 3) ox-LDL group; 4) simvastatin group; 5) Tongmai Decoction group. RT-PCR was used to determine the mRNA of NF-κB in the cells, Western Blot Assay was used to determine the protein content of NF-κB in the cells. Results 1) Compared with the cells in normal group and serum control group , the endothelial cells in ox-LDL group are seriously injured, while those in Tongmai Decoction group grow better; 2) Compared with the cells in normal group and fetal calf serum group, the expressions of NF-κB gene and protein are up-regulated in ox-LDL group(P<0.05, P<0.01); 3) Compared with the cells in ox-LDL group, the expression of NF-κB gene and protein in Tongmai Decoction group are significantly down-regulated, there is no difference between Tongmai Decoction group and simvastatin group(P>0.05). Conclusion Tongmai Decoction can protect the injured endothelial cells, up-regulate the expressions of NF-κB gene and protein content. 相似文献
102.
Xiangfei Chen Jianping Yao Fei Zeng Zhichao Deng 《Photonics Technology Letters, IEEE》2005,17(7):1390-1392
A novel single-longitudinal-mode (SLM) fiber ring laser that incorporates an equivalent phase-shifted fiber Bragg grating acting as an ultra-narrow bandpass filter in the laser cavity is proposed. The equivalent phase-shifted fiber Bragg grating has an ultra-narrow transmission bandwidth which ensures an SLM lasing. Stable SLM operation without mode hopping is demonstrated. 相似文献
103.
104.
煤层物性测井评价方法初探 总被引:6,自引:1,他引:5
依据煤岩的赋存方式和结构特点,利用电阻率和井径测井资料在不同煤质结构的煤层所表现的差异性,建立了2个指标(即深侧向电阻率与微球电阻率之间的比值,井径与钻头之间的比值)对煤质结构进行了准确的识别。用多元回归的概率模型建立了煤岩镜质反射率的测井计算模式,其结果与已有的煤心分析数据对比,两者具有较好的一致性。在综合分析的基础上,对煤层的重要物性参数煤阶、煤质结构进行了测井评价。 相似文献
105.
Xiang‐Dan Li Zhen‐Xin Zhong Sang‐Hoon Han Seung Hee Lee Myong‐Hoon Lee 《Polymer International》2005,54(2):406-411
From chloromethylated polyimide, a useful starting material for modification of aromatic polyimides, a thermocurable transparent polyimide having acrylate side groups was prepared. In the presence of 1,8‐diazabicyclo[5,4,0]undec‐7‐ene, chloromethylated polyimide was esterified with acrylic acid to synthesize poly(imide methylene acrylate). The polymer was soluble in organic solvent, which makes it possible to prepare a planar film by spin coating. The polymer film became insoluble after thermal treatment at 230 °C for 30 min. Optical transparency of the film at 400 nm (for 1 µm thickness) was higher than 98 % and not affected by further heating at 230 °C for 250 min. Adhesion properties measured by the ASTM D3359‐B method ranged from 4B to 5B. Preliminary results of planarization testing showed a high degree of planarization (DOP) value (>0.53). These properties demonstrate that poly(imide methylene acrylate) could be utilized as a thermocurable transparent material in fabricating display devices such as TFT‐LCD. Copyright © 2004 Society of Chemical Industry 相似文献
106.
Aimin Xiang Zhongjie Du Qinghua Zeng Chen Zhang Hangquan Li 《Polymer International》2005,54(10):1366-1370
This paper presents recent efforts on the preparation of flexible polyhedral particles via concentrated emulsion templating polymerization in which the hydrophilic monomer (acrylamide) and hydrophobic monomer (butyl acrylate) are polymerized simultaneously in the continuous and dispersed phase, respectively. Such templating polymerization has been enhanced in our systems owing to the introduction of acrylamide monomer and their higher polymerization rate in continuous phase as compared with butyl acrylate in dispersed phase. Diffusion between the different phases was also inhibited. Furthermore, the stability of the concentrated emulsion and the molecular weight of the produced poly(butyl acrylate) were found to be significantly affected by the amount of redox initiator. The morphology of the particles could be controlled by varying the volume fraction of the dispersed phase and the polyhedral particles were achieved at higher volume fraction. Copyright © 2005 Society of Chemical Industry 相似文献
107.
基于地理信息系统的天津房地产管理数据库 总被引:1,自引:0,他引:1
从地理信息系统CIS的组成开始.提出该类系统的组织与管理方法,同时重点介绍了在现阶段开发该类系统时所使用的高端技术,最后对GIS系统的发展趋势作出分析与顶测。 相似文献
108.
109.
110.
A block‐oriented approximate feedback linearization for control of a pneumatic cylinder positioning system is introduced and a rather detailed discussion is presented on the uncertain linearization residual characterization. It is shown that making use of the characterized gain–phase information of the linearized system leads to a more reasonable trade‐off between performance and stability in the QFT control design and thus results in high control performance. Simulation and experimental results are shown. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献