全文获取类型
收费全文 | 107473篇 |
免费 | 10150篇 |
国内免费 | 3603篇 |
专业分类
电工技术 | 6482篇 |
技术理论 | 6篇 |
综合类 | 6230篇 |
化学工业 | 24507篇 |
金属工艺 | 5765篇 |
机械仪表 | 5936篇 |
建筑科学 | 8703篇 |
矿业工程 | 2799篇 |
能源动力 | 2533篇 |
轻工业 | 7459篇 |
水利工程 | 1760篇 |
石油天然气 | 5451篇 |
武器工业 | 694篇 |
无线电 | 9876篇 |
一般工业技术 | 13746篇 |
冶金工业 | 4689篇 |
原子能技术 | 1118篇 |
自动化技术 | 13472篇 |
出版年
2024年 | 411篇 |
2023年 | 2210篇 |
2022年 | 2954篇 |
2021年 | 4247篇 |
2020年 | 3472篇 |
2019年 | 2886篇 |
2018年 | 3233篇 |
2017年 | 3406篇 |
2016年 | 3178篇 |
2015年 | 4213篇 |
2014年 | 5087篇 |
2013年 | 6595篇 |
2012年 | 6238篇 |
2011年 | 6467篇 |
2010年 | 5887篇 |
2009年 | 5955篇 |
2008年 | 5222篇 |
2007年 | 4989篇 |
2006年 | 5206篇 |
2005年 | 4622篇 |
2004年 | 3121篇 |
2003年 | 2703篇 |
2002年 | 2401篇 |
2001年 | 2137篇 |
2000年 | 2367篇 |
1999年 | 2770篇 |
1998年 | 2360篇 |
1997年 | 1913篇 |
1996年 | 2021篇 |
1995年 | 1667篇 |
1994年 | 1371篇 |
1993年 | 1077篇 |
1992年 | 853篇 |
1991年 | 676篇 |
1990年 | 554篇 |
1989年 | 507篇 |
1988年 | 407篇 |
1987年 | 346篇 |
1986年 | 307篇 |
1985年 | 253篇 |
1984年 | 226篇 |
1983年 | 211篇 |
1982年 | 197篇 |
1981年 | 236篇 |
1980年 | 188篇 |
1979年 | 175篇 |
1975年 | 202篇 |
1974年 | 188篇 |
1973年 | 365篇 |
1972年 | 212篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
41.
Poor aqueous solubility is one of the recurrent drawbacks of many compounds in medicinal chemistry. To overcome this limitation, the dilution of drug candidates from stock solutions of an organic solvent is common practice. However, the precise characterisation of these compounds in aqueous solutions is often neglected, leading to some uncertainties regarding the nature of the actual active species. In this communication, we demonstrate that two ruthenium complexes previously reported by our group for their chemotherapeutic potential against cancer, namely [Ru(DIP)2(sq)](PF6) and [Ru(DIP)2(3-methoxysq)](PF6), where DIP is 4,7-diphenyl-1,10-phenanthroline, sq=semiquinonate and 3-methoxysq=3-methoxysemiquinonate, form colloids in water-DMSO (1 % v/v) mixtures that are invisible to the naked eyes. [Ru(DIP)2(3-methoxysq)](PF6) was found to form a highly stable and monodispersed colloid with nanoaggregates of ∼25 nm. In contrast, [Ru(DIP)2(sq)](PF6) was found to form large reticulates of mostly spherical aggregates which size was found to increase over time. The difference in size and shape distribution of drug candidates is of tremendous significance as the study of their biological activity might be severely affected. Overall, we strongly believe that these observations should be taken into account by the scientific community working on the development of metal-based drugs with poor water solubility. 相似文献
42.
43.
Polymer Bulletin - Preparation of konjac glucomannan-grafted poly(trimethyl allyl ammonium chloride) (KGM-g-PTMAAC) was carried out using KGM as polysaccharide matrix and TMAAC as cationic... 相似文献
44.
Michael A. Clegg Prof. Nicholas C. O. Tomkinson Dr. Rab K. Prinjha Dr. Philip G. Humphreys 《ChemMedChem》2019,14(4):362-385
The bromodomain and extra terminal (BET) family of bromodomain-containing proteins (BCPs) have been the subject of extensive research over the past decade, resulting in a plethora of high-quality chemical probes for their tandem bromodomains. In turn, these chemical probes have helped reveal the profound biological role of the BET bromodomains and their role in disease, ultimately leading to a number of molecules in active clinical development. However, the BET subfamily represents just 8/61 of the known human bromodomains, and attention has now expanded to the biological role of the remaining 53 non-BET bromodomains. Rapid growth of this research area has been accompanied by a greater understanding of the requirements for an effective bromodomain chemical probe and has led to a number of new non-BET bromodomain chemical probes being developed. Advances since December 2015 are discussed, highlighting the strengths/caveats of each molecule, and the value they add toward validating the non-BET bromodomains as tractable therapeutic targets. 相似文献
45.
46.
47.
Qingna Gong Songtao Cao Yu Zhou Ruixin Wang Weizhou Jiao 《International Journal of Hydrogen Energy》2021,46(41):21442-21453
Ni2P nanoparticles and CdS nanorods were grew together on a mesoporous g-C3N4 through a facile in-situ solvothermal approach. Under visible light (λ > 400 nm), the as-prepared ternary PCN–CdS-5% Ni2P composite displays a high H2 evolution rate with 2905.86 μmol g?1 h?1, which is about 14, 18 and 279 times that of PCN–CdS, PCN–Ni2P and PCN, respectively. The enhanced photocatalytic activity is mainly attributed to the improved separation efficiency of the photocarriers by the type II PCN–CdS heterojunction and the effective extraction of photogenerated electrons by Ni2P. Meanwhile, Ni2P acts as co-catalyst to provide the photocatalytic active site for hydrogen reduction. In addition, PCN–CdS-5% Ni2P composite exerts good stability in 12-h cycles. 相似文献
48.
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
49.
Effects of different carbon sources and C/N values on nonvolatile taste components of Pleurotus eryngii
下载免费PDF全文
![点击此处可从《International Journal of Food Science & Technology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Wen Li Xiaobei Li Yan Yang Feng Zhou Yanfang Liu Shuai Zhou Hailong Yu 《International Journal of Food Science & Technology》2015,50(11):2360-2366
Pleurotus eryngii, the second largest industrial cultivation mushroom in China, is usually cultivated on substrates mainly consisting of sawdust and corncob. In this study, experiments were performed to determine the effects of different carbon sources and C/N values on nonvolatile taste components of P. eryngii. The effects of different carbon sources on nonvolatile taste components levels revealed that sawdust was beneficial to high levels of crude protein, amino acids, 5′‐nucleotides and equivalent umami concentration, while corncob was beneficial to high contents of carbohydrate, polysaccharides and trehalose. At the similar C/N values, relatively higher sawdust content was beneficial to umami amino acid production, while relatively higher corncob content was beneficial to high contents of carbohydrate, polysaccharides and mannitol. Higher C/N value was beneficial to high levels of crude protein, amino acids, 5′‐nucleotides and equivalent umami concentration, while lower C/N value was beneficial to high contents of carbohydrate, polysaccharides and trehalose. These results provided information for P. eryngii fruit body industrial cultivation to obtain specific nonvolatile taste components with high levels. 相似文献
50.