全文获取类型
收费全文 | 26159篇 |
免费 | 2333篇 |
国内免费 | 1560篇 |
专业分类
电工技术 | 1737篇 |
技术理论 | 2篇 |
综合类 | 2124篇 |
化学工业 | 3998篇 |
金属工艺 | 1437篇 |
机械仪表 | 1661篇 |
建筑科学 | 2140篇 |
矿业工程 | 665篇 |
能源动力 | 722篇 |
轻工业 | 2488篇 |
水利工程 | 557篇 |
石油天然气 | 1221篇 |
武器工业 | 295篇 |
无线电 | 3145篇 |
一般工业技术 | 2782篇 |
冶金工业 | 1128篇 |
原子能技术 | 349篇 |
自动化技术 | 3601篇 |
出版年
2024年 | 56篇 |
2023年 | 426篇 |
2022年 | 670篇 |
2021年 | 994篇 |
2020年 | 797篇 |
2019年 | 654篇 |
2018年 | 678篇 |
2017年 | 856篇 |
2016年 | 703篇 |
2015年 | 1063篇 |
2014年 | 1433篇 |
2013年 | 1671篇 |
2012年 | 1878篇 |
2011年 | 1950篇 |
2010年 | 1864篇 |
2009年 | 1724篇 |
2008年 | 1754篇 |
2007年 | 1670篇 |
2006年 | 1559篇 |
2005年 | 1291篇 |
2004年 | 991篇 |
2003年 | 882篇 |
2002年 | 921篇 |
2001年 | 796篇 |
2000年 | 589篇 |
1999年 | 483篇 |
1998年 | 368篇 |
1997年 | 288篇 |
1996年 | 235篇 |
1995年 | 196篇 |
1994年 | 165篇 |
1993年 | 100篇 |
1992年 | 98篇 |
1991年 | 57篇 |
1990年 | 58篇 |
1989年 | 46篇 |
1988年 | 24篇 |
1987年 | 13篇 |
1986年 | 10篇 |
1985年 | 2篇 |
1984年 | 7篇 |
1983年 | 5篇 |
1982年 | 7篇 |
1981年 | 2篇 |
1980年 | 7篇 |
1979年 | 2篇 |
1977年 | 3篇 |
1971年 | 2篇 |
1959年 | 1篇 |
1951年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 296 毫秒
11.
通过河南省渑池地区含锂铝土矿(岩)层工艺矿物学分析,查明铝土矿的物质组成、嵌布特征、伴生锂分布特征和赋存状态,为矿产综合利用提供理论依据。结果显示:该铝土矿Al2O3含量为54.8%,铝硅比值(A/S)为2.6,铝土矿层和粘土岩层中Li2O含量均高于伴生锂边界品位,粘土岩中锂更为富集;矿物组成除一水硬铝石之外,主要是以集合体形态产出的粘土矿物。采用稀酸解析、选矿测试和电子探针分析锂的赋存状态,查明矿石中锂主要是以类质同象置换形式赋存在伊利石和高岭石等粘土矿物中;选矿富锂尾矿中Li2O可富集到0.57%左右,是锂综合回收利用的重点研究对象。 相似文献
12.
Rong Zhang Hailong Hu Hai Chen Siqi Li Cheng Ying Shuai Huang Qingting Liu Xudong Fu Shengfei Hu Ching-Ping Wong 《应用聚合物科学杂志》2020,137(39):49186
Recently, thermal interface materials (TIMs) are in great demands for modern electronics. For mechanically mixed polymer composite TIMs, the thermal conductivity and the mechanical properties are generally lower than expected values due to the sharply increased viscosity and poor filler dispersion. This work shows that addition of a small amount of polyester-based hyperbranched polymer (HBP) avoided the trade-off in mechanically mixed ABS/hexagonal boron nitride (h-BN) composites. After adding 0.5 wt% HBP, the maximum h-BN content in the composites increased from 50 to 60 wt%. The out-of-plane, in-plane thermal conductivity, and tensile strength of ABS/h-BN with 50 wt% h-BN were 0.408, 0.517 W/mK, and 18 MPa, respectively, and were increased to 0.729, 0.847 W/mK, and 32 MPa by adding 0.5 wt% HBP, while 0.972, 1.12 W/mK, and 29.5 MPa were achieved for ABS/h-BN/HBP with 60 wt% h-BN. The morphological and rheological results proved that these enhancements are due to the improved h-BN dispersion by decreasing viscosity of composites during mixing. Theoretical modeling based on the modified effective medium theory confirmed such results and showed that the interfacial thermal resistance also decreased slightly. Thus, this work demonstrates a facile and scalable method for simultaneously improving the thermal conductivity and mechanical properties of thermoplastic-based TIMs. 相似文献
13.
14.
Xiaoyan Qiu Yongqiang Zhang Haitao Wu Rui Yang Jun Yang Rongjuan Liu Yong Liu Zhiping Zhou Tongfan Hao Yijing Nie 《Polymer International》2019,68(2):218-224
The crystallization of capped ultrathin polymer films is closely dependent on film thickness and interfacial interaction. Using dynamic Monte Carlo simulations, the crystallization behaviors of polymer films confined between two substrates were investigated. The crystallization rate of confined polymers is reduced with high interfacial interactions. Above a critical strength of interfacial interaction, polymer crystallization in the thin film is inhibited within the simulation time scales. An increase in film thickness leads to a rise in critical interfacial interaction. In thicker films, the chains have more space to change conformation to form crystal stems. In addition, there are fewer absorbed segments in confined chains for the thicker films, and thus the chains have stronger ability to adjust their conformation. Therefore an increase in film thickness can cause a reduction in the entropic barrier required for the formation of crystals and thus an increase in the critical interfacial interaction. © 2018 Society of Chemical Industry 相似文献
15.
16.
介绍机械制造厂燃煤锅炉的烟尘特点,分析滤料失效的原因,提出一套针对该工况的滤料解决方案。介绍针对复杂工况条件所选用的纤维种类以及复合面层原料成分配比的确定,最终选用针刺工艺加工并对该新产品的基本性能进行了测试分析。 相似文献
17.
18.
Kang Zhang Rong‐rong Wang Kai‐rui Zhang Fei Cheng Yu Tian Yi Lin Mi Zhou Pu‐xin Zhu 《Polymer International》2020,69(3):274-279
A series of hyperbranched poly(citric polyethylene glycol) (PCPEG) materials with varied polyethylene glycol (PEG) chain lengths as plasticizers were mixed with maize starch (MS) via cooking and film‐forming. The structure, pasting property, plasticization, aging property, moisture absorption and compatibility of plasticized starches were studied by means of Fourier transform infrared spectroscopy, X‐ray diffraction, rapid viscosity analysis, tension testing, moisture absorption measurements and scanning electron microscopy. Compared with PEG and citric acid, PCPEG was more effective in promoting starch chain movement and inhibiting the retrogradation of starch film. Also, PCPEG/MS had smaller moisture content. The longer the plasticizer chain, the better were the aging resistance and moisture resistance of starch. But with an increase of PEG chain length, mechanical properties of PCPEG/MS deteriorated and the compatibility between PCPEG and MS decreased. The hyperbranched derivative of PEG with longer chain exhibited improved plasticization and compatibility with starch. © 2019 Society of Chemical Industry 相似文献
19.
20.
Junyu Chen Yuze Li Yuming Jiang Liucheng Mao Mi Lai Lixia Jiang Huihui Liu Zongxiu Nie 《Advanced functional materials》2021,31(52):2106743
Cancer remains an intractable medical problem. Rapid diagnosis and identification of cancer are critical to differentiate it from nonmalignant diseases. High-throughput biofluid metabolic analysis has potential for cancer diagnosis. Nevertheless, the present metabolite analysis method does not meet the demand for high-throughput screening of diseases. Herein, a high-throughput, cost-effective, and noninvasive urine metabolic profiling method based on TiO2/MXene-assisted laser desorption/ionization mass spectrometry (LDI-MS) is presented for the efficient screening of bladder cancer (BC) and nonmalignant urinary disease. Combined with machine learning, TiO2/MXene-assisted LDI-MS enables high diagnostic accuracy (96.8%) for the classification of patient groups (including 47 BC and 46 ureteral calculus (UC) patients) from healthy controls (113 cases). In addition, BC patients can also be identified from noncancerous UC individuals with an accuracy of 88.3% in the independent test cohort. Furthermore, metabolite variations between BC and UC individuals are investigated based on relative quantification, and related pathways are also discussed. These results suggest that this method, based on urine metabolic patterns, provides a potential tool for rapidly distinguishing urinary diseases and it may pave the way for precision medicine. 相似文献