全文获取类型
收费全文 | 12801篇 |
免费 | 1641篇 |
国内免费 | 783篇 |
专业分类
电工技术 | 990篇 |
综合类 | 1003篇 |
化学工业 | 2014篇 |
金属工艺 | 992篇 |
机械仪表 | 836篇 |
建筑科学 | 964篇 |
矿业工程 | 338篇 |
能源动力 | 283篇 |
轻工业 | 1516篇 |
水利工程 | 267篇 |
石油天然气 | 490篇 |
武器工业 | 162篇 |
无线电 | 1325篇 |
一般工业技术 | 1436篇 |
冶金工业 | 532篇 |
原子能技术 | 188篇 |
自动化技术 | 1889篇 |
出版年
2024年 | 80篇 |
2023年 | 321篇 |
2022年 | 670篇 |
2021年 | 854篇 |
2020年 | 651篇 |
2019年 | 513篇 |
2018年 | 528篇 |
2017年 | 553篇 |
2016年 | 541篇 |
2015年 | 743篇 |
2014年 | 934篇 |
2013年 | 1014篇 |
2012年 | 1052篇 |
2011年 | 918篇 |
2010年 | 895篇 |
2009年 | 804篇 |
2008年 | 678篇 |
2007年 | 632篇 |
2006年 | 517篇 |
2005年 | 394篇 |
2004年 | 321篇 |
2003年 | 222篇 |
2002年 | 242篇 |
2001年 | 228篇 |
2000年 | 190篇 |
1999年 | 133篇 |
1998年 | 103篇 |
1997年 | 86篇 |
1996年 | 90篇 |
1995年 | 63篇 |
1994年 | 57篇 |
1993年 | 46篇 |
1992年 | 31篇 |
1991年 | 26篇 |
1990年 | 18篇 |
1989年 | 18篇 |
1988年 | 10篇 |
1987年 | 7篇 |
1986年 | 3篇 |
1985年 | 7篇 |
1984年 | 6篇 |
1983年 | 2篇 |
1982年 | 2篇 |
1980年 | 8篇 |
1976年 | 4篇 |
1972年 | 1篇 |
1970年 | 1篇 |
1968年 | 1篇 |
1959年 | 2篇 |
1951年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
Xiao-Mei Sha Li-Jun Zhang Wen-Mei Chen Guang-Yao Wang Jin-Lin Li Zi-Zi Hu Zong-Cai Tu 《International Journal of Food Science & Technology》2022,57(3):1573-1586
Thermal action in extraction process had effects on characteristic tryptic peptides identification and gelling properties of porcine gelatin. SDS-PAGE, HPLC-LTQ/Orbitrap high-resolution mass spectrometry, texture analyser and rheometer were used to evaluate collagen depolymerisation degree, characteristic tryptic peptides and gelling properties of gelatins prepared in various thermal actions. Results showed that with increasing temperature and time, depolymerisation degree enlarged, while gel strength, gelling and melting temperature decreased. Mass spectra showed that 47 and 49 common characteristic tryptic peptides were identified in gelatins extracted at 50 °C and 100 °C with various times, respectively. Moreover, 34 common characteristic tryptic peptides were identified in all gelatin samples. Further comparison between this work and our previous investigations yielded 20 common characteristic tryptic peptides, which stably exist in various thermal actions. These common characteristic tryptic peptides may be very helpful for the accurate authentication of porcine gelatin. 相似文献
3.
Yan Jing Zhu Rongying Wu Fan Zhao Ziyin Ye Huan Hou Mengying Liu Yong Yin Lichen 《Nano Research》2020,13(10):2706-2715
Nano Research - Insufficient intratumoral penetration greatly hurdles the anticancer performance of nanomedicine. To realize highly efficient tumor penetration in a precisely and spatiotemporally... 相似文献
4.
5.
6.
Wan Huan Wang Hui Scotney Bryan Liu Jun Ng Wing W. Y. 《Multimedia Tools and Applications》2020,79(39-40):29327-29352
Multimedia Tools and Applications - In many real-world classification problems there exist multiple subclasses (or clusters) within a class; in other words, the underlying data distribution is... 相似文献
7.
The titanium carbides are potential candidates to achieve both high hardness and refractory property. We carried out a structural search for titanium carbides at three pressures of 0 GPa, 30 GPa and 50 GPa. A phase diagram of the Ti-C system at 0 K was obtained by elucidating formation enthalpies as a function of compositions, and their mechanical and metallic properties of titanium carbides were investigated systematically. We also discussed the relation of titanium concentration to the both mechanical and metallic properties of titanium carbides. It has been found that the average valence electron density and tractility improved at higher concentrations of titanium, while the degree of covalent bonding directionality decreased. To this effect, the hardness of titanium carbide decreases as the content of titanium increases. Our results indicated that the titanium content significantly affected the metallic properties of the Ti-C system. 相似文献
8.
In this paper, we consider the problem of designing optimal asynchronous wake-up schedules to facilitate distributed power management and neighbor discovery in multihop wireless networks. We first formulate it as a block design problem and derive the fundamental trade-offs between wake-up latency and the average duty cycle of a node. After the theoretical foundation is laid, we then devise a neighbor discovery and schedule bookkeeping protocol that can operate on the optimal wake-up schedule derived. To demonstrate the usefulness of asynchronous wake-up, we investigate the efficiency of neighbor discovery and the application of on-demand power management, which overlays a desirable communication schedule over the wake-up schedule mandated by the asynchronous wake-up mechanism. Simulation studies demonstrate that the proposed asynchronous wake-up protocol has short discovery time which scales with the density of the network; it can accommodate various traffic characteristics and loads to achieve an energy savings that can be as high as 70 percent, while the packet delivery ratio is comparable to that without power management. 相似文献
9.
土石过水围堰过水期最不利工况及其流量确定 总被引:7,自引:0,他引:7
本文系统分析了影响土石过水围堰溢流工况的主要因素,提出衡量最不利工况的指标和确定员不利流量的方法,为土石过水围堰堰体下游护坡结构及消能防冲设施设计提供了理论依据。通过理论计算结果与模型试验现场观测资料数据对比分析,说明提出的过水期最不利流量判别方法是符合实际情况的。 相似文献
10.
Fastmet工艺评述 总被引:5,自引:0,他引:5
介绍了Fastmet工艺及发展状况,并对工艺特点和指标进行了分析。使用冷固结含碳球团和转底炉使该工艺可直接采用粉矿和提高生产效率,但因硫含量高、铁品位低而产品质量较差。不过投资和生产成本与传统工艺比较却占有较大优势。 相似文献