首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   323篇
  免费   27篇
  国内免费   29篇
化学   134篇
力学   68篇
综合类   1篇
数学   112篇
物理学   64篇
  2025年   3篇
  2024年   8篇
  2023年   19篇
  2022年   14篇
  2021年   25篇
  2020年   50篇
  2019年   33篇
  2018年   12篇
  2017年   15篇
  2016年   11篇
  2015年   9篇
  2014年   23篇
  2013年   15篇
  2012年   12篇
  2011年   23篇
  2010年   13篇
  2009年   11篇
  2008年   2篇
  2007年   5篇
  2006年   3篇
  2005年   2篇
  2004年   4篇
  2003年   3篇
  2002年   4篇
  2001年   6篇
  1999年   4篇
  1998年   2篇
  1997年   1篇
  1996年   1篇
  1995年   1篇
  1993年   1篇
  1990年   4篇
  1989年   1篇
  1988年   3篇
  1987年   7篇
  1986年   4篇
  1978年   3篇
  1975年   1篇
  1974年   3篇
  1972年   2篇
  1971年   3篇
  1970年   1篇
  1969年   1篇
  1968年   1篇
  1967年   2篇
  1966年   3篇
  1965年   2篇
  1958年   1篇
  1954年   1篇
  1948年   1篇
排序方式: 共有379条查询结果,搜索用时 15 毫秒
1.
Herein we summarized some clean preparation examples to emphasize the concept of dual roles design (or named as “two birds one stone strategy”) in green and sustainable chemistry. In those examples, the reactants and/or solvent play dual roles rendering a cleaner organic preparation process. Consequently, both the chemical waste and manufacturing cost could be reduced.  相似文献   
2.
在方差和均值有限的条件下,得到了随机环境中迁入分枝过程对应的规范化过程的几乎处处收敛性和L^2收敛性.这对于刻画过程本身的发散速度,具有重要的意义.  相似文献   
3.
In this paper, the singular value decompositions of anti-symmetric matrices and anti-bisymmetric matrices are presented, and a class of parameterized inverse singular value problem for anti-bisymmetric matrices is solved. Numerical examples which confirm our theory are presented.  相似文献   
4.
    
《中国化学快报》2020,31(12):2991-2992
The recent development of selective oxidation of aromatic sulfides with molecular oxygen was highlighted. The sulfoxides and sulfones could be obtained by simply switching the reaction media, i.e., bis(2-butoxyethyl)ether (BBE) or poly(ethylene glycol)dimethyl ether (PEGDME). The application of the high-boiling-point polyether as an initiator and green media can eliminate the need of large quantities of additives and volatile solvents. This strategy represents an economic and eco-friendly method that could find potential applications.  相似文献   
5.
    
《中国化学快报》2020,31(12):2989-2990
The recent molecular iodine catalyzed [1,2]-rearrangement of aryl amines and 3-amino-1H-indazolesfor the synthesis of 1,2,3-benzotriazines is highlighted.  相似文献   
6.
《中国化学快报》2020,31(7):1855-1858
By virtue of electrochemistry, a series of α,α-dihaloacetophenones were easily obtained with good to excellent yields. This electrochemical procedure was taken in a divided cell with constant current in aqueous media. The reaction can be carried out smoothly at room temperature under metal and oxidant free condition, which provides an eco-friendly synthesis for the α,α-dihaloacetophenone derivatives.  相似文献   
7.
    
《中国化学快报》2020,31(10):2839-2842
Electrochemical detection is an efficient method for the detection of Bisphenol A (BPA). Herein, a sensitive photo-electrochemical sensor based on two-dimensional (2D) TiO2 (001) nanosheets was fabricated and then used for BPA electrochemical detection. Upon light irradiation, the 2D TiO2 (001) nanosheets electrode provided a lower detection limit of BPA detection compared with an ambient electrochemical determination. The low detection limit is ∼5.37 nmol/L (S/N = 3). Furthermore, profiting from the photoelectric characteristics, the 2D TiO2 (001) nanosheets electrode exhibits a nice regeneration property. After 45 min of light irradiation, the electrochemical signal was regenerated from 14.7% to 82.9% of the original signal at the 6th cycle. This is attributed to the non-selective OH mediation produced by the 2D TiO2 (001) nanosheets mineralizing anodic polymeric products and resuming surface reactive sites. This investigation indicates that photo-assistance is an efficient method to improve the electrochemical sensor for detecting BPA in water environments.  相似文献   
8.
The Au−S bond is the classic way to functionalize gold nanoparticles (AuNPs). However, cleavage of the bond by biothiols and other chemicals is a long-standing problem hindering practical applications, especially in cells. Instead of replacing the thiol by a carbene or selenol for stronger adsorption, it is now shown that the Pt−S bond is much more stable, fully avoiding cleavage by biothiols. AuNPs were deposited with a thin layer of platinum, and an AuNP@Pt-S nanoflare was constructed to detect the miRNA-21 microRNA in living cells. This design retained the optical and cellular uptake properties of DNA-functionalized AuNPs, while showing high-fidelity signaling. It discriminated target cancer cells even in a mixed-cell culture system, where the Au-S based nanoflare was less sensitive. Compared to previous methods of changing the ligand chemistry, coating a Pt shell is more accessible, and previously developed methods for AuNPs can be directly adapted.  相似文献   
9.
    
Micro- and spongiform nanocrystalline Zn2V2O7 compounds were synthesized by hydrothermal and solid-state reaction techniques, and their morphological features were investigated by scanning electron microscopy (SEM). The grain size ranges of the produced powders were 3–15, 0.5–2 μm, and 50–500 nm. The luminescence spectra of these compounds were measured under pulse cathode beam and photoexcitation (200–400 nm). The luminescence decay properties of Zn2V2O7 were studied.It is found that the intensity, maximum position of luminescence spectra and luminescence decay time of Zn2V2O7 samples depend considerably on the grain size of the synthesized powders. The processes of energy relaxation in Zn2V2O7 and the observed size effect on the luminescence properties are also discussed.  相似文献   
10.
    
Pumpkin seed oil (PSO), which is a valuable compound with high nutritional value used for the prevention of various chronic diseases, is prone to oxidation. In this work, small and uniform (su) ovalbumin (OVA) and pectin (PEC) were used to stabilize PSO in the form of an emulsion. The results showed that suOVA-PEC-PSO emulsion with a droplet size of 9.82 ± 0.05 μm was successfully self-assembled from PSO, PEC, and suOVA solution (with a droplet size of 230.13 ± 14.10 nm) treated with 300 W ultrasound, owing to the formation of a more stable interfacial film on the surface of droplets. The interfacial, rheological, emulsifying, and antioxidant properties of the suOVA-PES-PSO emulsions were excellent, owing to the synergistic effects between PEC and suOVA solution. Moreover, the physical stability of the suOVA-PEC-PSO emulsions to salt stress, a freeze-thaw cycle, and heat treatment was also increased and the oxidation of linolenic acid was notably delayed. These results have extended the food-related applications of OVA and PSO, and provide a promising foundation for further exploration of the self-assembly of composite emulsions by small and uniform proteins.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号