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   1548篇
  免费   43篇
  国内免费   7篇
化学   837篇
晶体学   22篇
力学   111篇
数学   163篇
物理学   465篇
  2023年   17篇
  2022年   19篇
  2021年   23篇
  2020年   32篇
  2019年   33篇
  2018年   38篇
  2017年   32篇
  2016年   43篇
  2015年   33篇
  2014年   58篇
  2013年   128篇
  2012年   110篇
  2011年   101篇
  2010年   68篇
  2009年   71篇
  2008年   79篇
  2007年   77篇
  2006年   55篇
  2005年   51篇
  2004年   32篇
  2003年   34篇
  2002年   20篇
  2001年   9篇
  2000年   16篇
  1999年   10篇
  1998年   9篇
  1997年   11篇
  1996年   13篇
  1995年   20篇
  1994年   11篇
  1993年   14篇
  1992年   8篇
  1991年   13篇
  1990年   12篇
  1989年   17篇
  1988年   11篇
  1986年   11篇
  1985年   13篇
  1984年   19篇
  1982年   13篇
  1981年   17篇
  1980年   12篇
  1979年   14篇
  1978年   9篇
  1977年   11篇
  1976年   10篇
  1975年   10篇
  1974年   9篇
  1973年   7篇
  1936年   13篇
排序方式: 共有1598条查询结果,搜索用时 234 毫秒
971.
The European Physical Journal E - We synthesized and characterized the colloidal suspensions of $\mathrm{FeO}\cdot\mathrm{Fe}_{(2-x)}\mathrm{Nd}_{x} \mathrm{O_{3}}$ nanoparticles with x = 0.00,...  相似文献   
972.
973.
974.
The synergistic effects of iron and copper in copper ferrite nanoparticles for the N-arylation of heterocycles with aryl halides were demonstrated. The magnetic nature of the catalyst facilitates its removal from the reaction medium for further use. Negligible leaching of Cu and Fe in consecutive cycles makes the catalyst economical and environmentally benign for C-N cross-coupling reactions.  相似文献   
975.
Bhowmik  Ratul  Manaithiya  Ajay  Vyas  Bharti  Nath  Ranajit  Rehman  Sara  Roy  Shubham  Roy  Ratna 《Structural chemistry》2022,33(3):815-831
Structural Chemistry - The Ebola virus is a deadly pathogen that causes a highly lethal hemorrhagic fever illness in humans, sometimes known as Ebola virus sickness (EVD). The Ebola virus...  相似文献   
976.
Smarter and minimization of devices are consistently substantial to shape the energy landscape. Significant amounts of endeavours have come forward as promising steps to surmount this formidable challenge. It is undeniable that material scientists were contemplating smarter material beyond purely inorganic or organic materials. To our delight, metal-organic frameworks (MOFs), an inorganic-organic hybrid scaffold with unprecedented tunability and smart functionalities, have recently started their journey as an alternative. In this review, we focus on such propitious potential of MOFs that was untapped over a long time. We cover the synthetic strategies and (or) post-synthetic modifications towards the formation of conductive MOFs and their underlying concepts of charge transfer with structural aspects. We addressed theoretical calculations with the experimental outcomes and spectroelectrochemistry, which will trigger vigorous impetus about intrinsic electronic behaviour of the conductive frameworks. Finally, we discussed electrocatalysts and energy storage devices stemming from conductive MOFs to meet energy demand in the near future.  相似文献   
977.
Goel  Shruti  Khulbe  Mihir  Aggarwal  Anshul  Kathuria  Abha 《Molecular diversity》2022,26(5):2939-2948

In the current scenario, flow chemistry is emerging as a significant technology in the field of organic synthesis. This miniaturized protocol including microreactors facilitates excellent heat transfer, low solvent wastage, lesser reaction time, a safer environment for reagent handling and appreciable yields of desired products. Thus, this “enabling technology” has a great scope in the synthesis and preparation of a variety of heterocycles that require toxic reagents as starting materials. This review discusses the recent advances (2020–2021) in continuous flow strategy for synthesis and derivatization of variety of heterocyclic entities, of different ring size, using different approaches. This also highlights the advantages of different combined techniques like Microwave assisted heating, electrochemical flow cell, LED light source, NMR and FT-IR analysis, etc., that enables utilization of various mechanisms and real-time monitoring of reactions leading to improved results.

Graphic abstract
  相似文献   
978.
A new analogue of graphene containing boron, carbon and nitrogen (BCN) has been obtained by the reaction of high‐surface‐area activated charcoal with a mixture of boric acid and urea at 900 °C. X‐ray photoelectron spectroscopy and electron energy‐loss spectroscopy reveal the composition to be close to BCN. The X‐ray diffraction pattern, high‐resolution electron microscopy images and Raman spectrum indicate the presence of graphite‐type layers with low sheet‐to‐sheet registry. Atomic force microscopy reveals the sample to consist of two to three layers of BCN, as in a few‐layer graphene. BCN exhibits more electrical resistivity than graphene, but weaker magnetic features. BCN exhibits a surface area of 2911 m2 g?1, which is the highest value known for a BxCyNz composition. It exhibits high propensity for adsorbing CO2 (≈100 wt %) at 195 K and a hydrogen uptake of 2.6 wt % at 77 K. A first‐principles pseudopotential‐based DFT study shows the stable structure to consist of BN3 and NB3 motifs. The calculations also suggest the strongest CO2 adsorption to occur with a binding energy of 3.7 kJ mol?1 compared with 2.0 kJ mol?1 on graphene.  相似文献   
979.
Thin films of pure Pd and composite of Pd and 1% multiwalled carbon nanotube have been obtained on glassy carbon electrodes by borohydride reduction method and investigated as electrocatalysts for the oxidation of phenol in acid medium at 25 °C, using cyclic voltammetry (CV), chronopotentiometry, and high-performance liquid chromatography. The CV study showed that both the electrocatalysts are quite stable and active for the phenol oxidation in acid medium. Further, these electrodes do not seem to undergo deactivation due to intermediates and products formed during the phenol oxidation. With the increase in phenol concentration from 2 to 25 mM, the peak current (I p) increases initially, reaches maximum at about 15 mM, and tends to decrease thereafter. The peak potential (E p) value was found to be practically unchanged with phenol concentration. The rate for phenol oxidation (I p) at the surface of both the electrocatalysts increased with the decrease in pH of the reaction mixture. The electrocatalytic activity of the composite electrode was, however, higher than that of pure Pd under similar experimental conditions. Benzoquinone and hydroquinone were identified as the major phenol degradation intermediate products.  相似文献   
980.
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