全文获取类型
收费全文 | 31529篇 |
免费 | 3190篇 |
国内免费 | 1336篇 |
专业分类
电工技术 | 1878篇 |
技术理论 | 1篇 |
综合类 | 1773篇 |
化学工业 | 4877篇 |
金属工艺 | 1757篇 |
机械仪表 | 1896篇 |
建筑科学 | 2187篇 |
矿业工程 | 731篇 |
能源动力 | 896篇 |
轻工业 | 2384篇 |
水利工程 | 660篇 |
石油天然气 | 1333篇 |
武器工业 | 291篇 |
无线电 | 3980篇 |
一般工业技术 | 3922篇 |
冶金工业 | 2529篇 |
原子能技术 | 489篇 |
自动化技术 | 4471篇 |
出版年
2024年 | 62篇 |
2023年 | 583篇 |
2022年 | 987篇 |
2021年 | 1520篇 |
2020年 | 1218篇 |
2019年 | 1012篇 |
2018年 | 1069篇 |
2017年 | 1123篇 |
2016年 | 987篇 |
2015年 | 1429篇 |
2014年 | 1851篇 |
2013年 | 2147篇 |
2012年 | 2325篇 |
2011年 | 2276篇 |
2010年 | 1925篇 |
2009年 | 1742篇 |
2008年 | 1669篇 |
2007年 | 1582篇 |
2006年 | 1445篇 |
2005年 | 1154篇 |
2004年 | 825篇 |
2003年 | 728篇 |
2002年 | 753篇 |
2001年 | 628篇 |
2000年 | 510篇 |
1999年 | 495篇 |
1998年 | 744篇 |
1997年 | 520篇 |
1996年 | 438篇 |
1995年 | 294篇 |
1994年 | 279篇 |
1993年 | 218篇 |
1992年 | 172篇 |
1991年 | 144篇 |
1990年 | 117篇 |
1989年 | 112篇 |
1988年 | 84篇 |
1987年 | 62篇 |
1986年 | 78篇 |
1985年 | 64篇 |
1984年 | 53篇 |
1983年 | 52篇 |
1982年 | 52篇 |
1981年 | 46篇 |
1980年 | 40篇 |
1979年 | 31篇 |
1977年 | 55篇 |
1976年 | 87篇 |
1975年 | 26篇 |
1974年 | 22篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
1.
Quan Nguyen Minh Quoc Dat Lai Hoang Nguy Minh Minh Tu Tran Kieu Ngoc Lam Gia Uyen Le My Phung Hang Hoang Dung Nguyen Tran Diem Ai Chau Ngoc Thuc Trinh Doan 《International Journal of Food Science & Technology》2022,57(7):4507-4517
To prevent the adulteration of agricultural resources and provide a solution to enhance the green coffee bean supply chain, authentication using the near-infrared spectroscopy (NIRS) technique was investigated. Partial least square with discrimination analysis (PLS-DA) models combined with various preprocessing methods were built from NIR spectra of 153 Vietnamese green coffee samples. The model combined with the standard normal variate and the first order of derivative yielded excellent performance in predicting coffee species with the error cross-validation of 0.0261. PLS-DA model of mean centre and first-order derivative spectra also yielded good performance in verifying geographical indication of green coffee with the error of 0.0656. By contrast, the predicting abilities of post-harvest methods were poor. The overall results showed a high potential of the NIRS in online authentication practices. 相似文献
2.
通过试验得出了C105混凝土100 mm×100 mm×100 mm立方体非标准试件抗压强度换算系数以及C105混凝土的标准方差和强度变异系数。采用理论计算,得到了棱柱体抗压强度与立方体抗压强度的比值αc1,并与试验实测平均值进行了比较,验证了理论计算方法的可行性。此外,通过对比分析,探讨了直接外延法和引用公式法两种C105混凝土设计参数计算方法的正确性,研究结果可为C105管桩混凝土的设计和应用提供参考。 相似文献
3.
Fire Technology - The current research on individual risks mainly focuses on the individual risk considering a single fire or the spatial distribution of multiple fires. It is more realistic to... 相似文献
4.
6.
Neural Processing Letters - Semi-supervised learning techniques have been attracting increasing interests in many machine learning fields for its effectiveness in using labeled and unlabeled... 相似文献
7.
以煤气化渣(CGS)为载体,采用溶胶凝胶法制备了Fe3+掺杂改性的Fe3+-TiO2@CGS光催化剂复合材料,利用电子扫描显微镜、N2物理吸附仪、热重分析仪等设备对复合材料进行了表征,并以苯酚废水为目标污染物,考察了该复合材料的光催化性能.实验结果表明,250mL浓度为300mg·L-1苯酚溶液在光催化反应器进行处理,当Fe3+-TiO2@CGS复合材料投入量为1.5g、溶液pH值为7、光源功率为600W时,苯酚溶液COD的去除效果最明显,去除率达64.8%. 相似文献
8.
Dr. Thomas Le Bihan Dr. Cathryn H. S. Driver Dr. Thomas Ebenhan Dr. Nathalie Le Bris Dr. Jan Rijn Zeevaart Prof. Dr. Raphaël Tripier 《ChemMedChem》2021,16(5):809-821
An improved glucose-chelator-albumin bioconjugate (GluCAB) derivative, GluCAB-2Mal, has been synthesized and studied for in vivo 64Cu-PET/CT imaging in breast cancer mice models together with its first-generation analogue GluCAB-1Mal. The radioligand works on the principle of tumor targeting through the enhanced permeability and retention (EPR) effect with a supportive role played by glucose metabolism. [64Cu]Cu-GluCAB-2Mal (99 % RCP) exhibited high serum stability with immediate binding to serum proteins. In vivo experiments for comparison between tumor targeting of [64Cu]Cu-GluCAB-2Mal and previous-generation [64Cu]Cu-GluCAB-1Mal encompassed microPET/CT imaging and biodistribution analysis in an allograft E0771 breast cancer mouse model. Tumor uptake of [64Cu]Cu-GluCAB-2Mal was clearly evident with twice as much accumulation as compared to its predecessor and a tumor/muscle ratio of up to 5 after 24 h. Further comparison indicated a decrease in liver accumulation for [64Cu]Cu-Glu-CAB-2Mal. 相似文献
9.
CoCrNiCux (x=0.16,0.33,0.75,and 1) without macro-segregation medium-entropy alloys (MEAs) was prepared using laser directed energy deposition (LDED).The microstructure and mechanical properties of CoCrNiCux alloys with increas-ing Cu content were investigated.The results indicate that a single matrix phase changes into a dual-phase structure and the tensile fracture behaviors convert from brittle to plastic pattern with increasing Cu content in CoCrNiCux alloys.In addi-tion,the tensile strength of CoCrNiCux alloys increased from 148 to 820 MPa,and the ductility increased from 1 to 11%with increasing Cu content.The nano-precipitated particles had a mean size of approximately 20 nm in the Cu-rich phase area,and a large number of neatly arranged misfit dislocations were observed at the interface between the two phases due to Cu-rich phase precipitation in the CoCrNiCu alloy.These misfit dislocations hinder the movement of dislocations during tensile deformation,as observed through transmission electron microscopy.This allows the CoCrNiCu alloy to reach the largest tensile strength and plasticity,and a new strengthening mechanism was achieved for the CoCrNiCu alloy.Moreover,twins were observed in the matrix phase after tensile fracture.Simultaneously,the dual-phase structure with different elastic moduli coordinated with each other during the deformation process,significantly improving the plasticity and strength of the CoCrNiCu alloy. 相似文献
10.
Dr. Barbara Wienen-Schmidt Matthias Oebbeke Dr. Khang Ngo Prof. Dr. Andreas Heine Prof. Dr. Gerhard Klebe 《ChemMedChem》2021,16(1):292-300
In lead optimization, protein crystallography is an indispensable tool to analyze drug binding. Binding modes and non-covalent interaction inventories are essential to design follow-up synthesis candidates. Two protocols are commonly applied to produce protein–ligand complexes: cocrystallization and soaking. Because of its time and cost effectiveness, soaking is the more popular method. Taking eight ligand hinge binders of protein kinase A, we demonstrate that cocrystallization is superior. Particularly for flexible proteins, such as kinases, and larger ligands cocrystallization captures more reliable the correct binding pose and induced protein adaptations. The geometrical discrepancies between soaking and cocrystallization appear smaller for fragment-sized ligands. For larger flexible ligands that trigger conformational changes of the protein, soaking can be misleading and underestimates the number of possible polar interactions due to inadequate, highly impaired positions of protein amino-acid side and main chain atoms. Thus, if applicable cocrystallization should be the gold standard to study protein–ligand complexes. 相似文献