全文获取类型
收费全文 | 186877篇 |
免费 | 18879篇 |
国内免费 | 10656篇 |
专业分类
电工技术 | 14454篇 |
技术理论 | 4篇 |
综合类 | 14254篇 |
化学工业 | 27299篇 |
金属工艺 | 10725篇 |
机械仪表 | 11891篇 |
建筑科学 | 15283篇 |
矿业工程 | 5711篇 |
能源动力 | 5609篇 |
轻工业 | 14658篇 |
水利工程 | 4357篇 |
石油天然气 | 8401篇 |
武器工业 | 2010篇 |
无线电 | 22209篇 |
一般工业技术 | 19990篇 |
冶金工业 | 9741篇 |
原子能技术 | 2117篇 |
自动化技术 | 27699篇 |
出版年
2024年 | 865篇 |
2023年 | 2923篇 |
2022年 | 5864篇 |
2021年 | 8079篇 |
2020年 | 6081篇 |
2019年 | 4791篇 |
2018年 | 5363篇 |
2017年 | 6291篇 |
2016年 | 5584篇 |
2015年 | 8065篇 |
2014年 | 10136篇 |
2013年 | 12441篇 |
2012年 | 14133篇 |
2011年 | 14900篇 |
2010年 | 13576篇 |
2009年 | 12867篇 |
2008年 | 12754篇 |
2007年 | 12004篇 |
2006年 | 10884篇 |
2005年 | 8548篇 |
2004年 | 6030篇 |
2003年 | 5136篇 |
2002年 | 4937篇 |
2001年 | 4273篇 |
2000年 | 3492篇 |
1999年 | 2866篇 |
1998年 | 2330篇 |
1997年 | 1783篇 |
1996年 | 1605篇 |
1995年 | 1327篇 |
1994年 | 1116篇 |
1993年 | 789篇 |
1992年 | 607篇 |
1991年 | 462篇 |
1990年 | 382篇 |
1989年 | 346篇 |
1988年 | 269篇 |
1987年 | 213篇 |
1986年 | 203篇 |
1985年 | 177篇 |
1984年 | 169篇 |
1983年 | 139篇 |
1982年 | 120篇 |
1981年 | 142篇 |
1980年 | 126篇 |
1979年 | 121篇 |
1978年 | 96篇 |
1977年 | 124篇 |
1976年 | 147篇 |
1975年 | 87篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
Jiri Patocka Ran Wu Eugenie Nepovimova Martin Valis Wenda Wu Kamil Kuca 《International journal of molecular sciences》2021,22(4)
Mushroom poisoning has always been a threat to human health. There are a large number of reports about ingestion of poisonous mushrooms every year around the world. It attracts the attention of researchers, especially in the aspects of toxin composition, toxic mechanism and toxin application in poisonous mushroom. Inocybe is a large genus of mushrooms and contains toxic substances including muscarine, psilocybin, psilocin, aeruginascin, lectins and baeocystin. In order to prevent and remedy mushroom poisoning, it is significant to clarify the toxic effects and mechanisms of these bioactive substances. In this review article, we summarize the chemistry, most known toxic effects and mechanisms of major toxic substances in Inocybe mushrooms, especially muscarine, psilocybin and psilocin. Their available toxicity data (different species, different administration routes) published formerly are also summarized. In addition, the treatment and medical application of these toxic substances in Inocybe mushrooms are also discussed. We hope that this review will help understanding of the chemistry and toxicology of Inocybe mushrooms as well as the potential clinical application of its bioactive substances to benefit human beings. 相似文献
72.
为了解决被动雷达系统中的多发射源定位问题,提出了一种基于多重信号分类(MUSIC)算法和图像膨胀(IE)算法的直接定位方法。该方法结合了谱分析中的MUSIC思想,通过对接收量测协方差矩阵进行特征分析求解目标的位置。首先,在目标个数未知的前提下,利用Akaike信息准则(AIC)来确定模型阶数;然后,推导了基于MUSIC的定位代价函数;之后,利用图像膨胀算法处理得到的代价函数平面;最后,膨胀处理后的输出为目标个数及目标位置的估计值。提出的算法有效地解决了目标检测及提取的问题,能够确定多个目标的位置坐标,为后续的定位性能分析提供可能性,也保证了算法的完整性。进一步地分析了多个临近目标情况下影响目标提取性能的主要因素。 相似文献
73.
Wei LingNan Wang ZhenHua Zhang ZhiDong Liu Chieh-Wen Gao Xuan P. A. 《Nano Research》2020,13(5):1332-1338
Nano Research - We report the composition and back-gate voltage tuned transport properties of ternary compound Bi2(Te1−xSex)3 nanowires synthesized by chemical vapor deposition (CVD). It is... 相似文献
74.
Dr. Lina Liang Tong-You Wade Wei Pei-Yu Wu Wouter Herrebout Ming-Daw Tsai Prof. Stéphane P. Vincent 《Chembiochem : a European journal of chemical biology》2020,21(20):2982-2990
d -Glycero-d -manno-heptose-1β,7-bisphosphate (HBP) and d -glycero-d -manno-heptose-1β-phosphate (H1P) are bacterial metabolites that were recently shown to stimulate inflammatory responses in host cells through the activation of the TIFA-dependent NF-κB pathway. To better understand structure-based activity in relation to this process, a family of nonhydrolyzable phosphonate analogues of HBP and H1P was synthesized. The inflammation modulation by which these molecules induce the TIFA-NF-κB signal axis was evaluated in vivo at a low-nanomolar concentration (6 nM) and compared to that of the natural metabolites. Our data showed that three phosphonate analogues had similar stimulatory activity to HBP, whereas two phosphonates antagonized HBP-induced TIFA-NF-κB signaling. These results open new horizons for the design of pro-inflammatory and innate immune modulators that could be used as vaccine adjuvant. 相似文献
75.
76.
Zu Guoqing Lu Yukuan Yan Yi Zhang Xiaoming Zhao Jingwei Du Wei Ran Xu Jiang Zhengyi 《Metals and Materials International》2020,26(2):248-259
Metals and Materials International - The flow behaviour and microstructure characteristics of a ferritic stainless steel were investigated using plain strain compression test on a Gleeble 3500... 相似文献
77.
Martin Michálek Monika Michálková Gurdial Blugan Jakob Kuebler 《Ceramics International》2018,44(3):3255-3260
Up to now, commercially available alumina ceramics were claimed to have strength between 400 and 550 MPa. However, our study shows strength ~ 2 times higher for commercially available alumina than commonly believed. The average and characteristic strength, measured on 31 pure alumina ceramic discs by ball on three balls (B3B) test, were 1205 ± 93 MPa and 1257 MPa, respectively, with a Weibull modulus of m = 11.8. Tested specimens were in form of discs with a diameter of 5 mm and thickness 0.5 mm. The grain size distribution of the alumina is bimodal with an average grain size of ~ 850 nm measured at the surface. The fracture reveals a mixed transgranular / intergranular failure mode. To avoid incorporation of additional flaws, the discs were tested as sintered. The characteristic flexural strength measured in B3B was recalculated according to Weibull theory for standard 4-point bending bars of size 3 × 4 × 45 mm as bend 856 MPa. The measured strength of nearly 900 MPa shows the potential of strength for high purity alumina ceramics. 相似文献
78.
79.
80.
Bill Robert Fleck Martin Troya Javier Mayerhofer Tanja Wimmer Manuel 《Software and Systems Modeling》2019,18(2):1017-1046
Software and Systems Modeling - Many model transformation scenarios require flexible execution strategies as they should produce models with the highest possible quality. At the same time,... 相似文献