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   7518篇
  免费   354篇
  国内免费   61篇
化学   4872篇
晶体学   62篇
力学   282篇
数学   816篇
物理学   1901篇
  2023年   64篇
  2022年   133篇
  2021年   322篇
  2020年   290篇
  2019年   289篇
  2018年   308篇
  2017年   242篇
  2016年   349篇
  2015年   278篇
  2014年   351篇
  2013年   648篇
  2012年   532篇
  2011年   560篇
  2010年   380篇
  2009年   318篇
  2008年   347篇
  2007年   335篇
  2006年   253篇
  2005年   199篇
  2004年   164篇
  2003年   127篇
  2002年   98篇
  2001年   92篇
  2000年   71篇
  1999年   68篇
  1998年   34篇
  1997年   46篇
  1996年   54篇
  1995年   44篇
  1994年   53篇
  1993年   48篇
  1992年   51篇
  1991年   49篇
  1990年   35篇
  1989年   32篇
  1988年   40篇
  1987年   41篇
  1986年   29篇
  1985年   60篇
  1984年   46篇
  1983年   37篇
  1982年   42篇
  1981年   24篇
  1980年   62篇
  1979年   32篇
  1978年   34篇
  1977年   41篇
  1976年   28篇
  1973年   20篇
  1968年   18篇
排序方式: 共有7933条查询结果,搜索用时 15 毫秒
1.
Molecular Diversity - The terminal oxidases of the oxidative phosphorylation pathway play a significant role in the survival and growth of M. tuberculosis, targeting these components lead to...  相似文献   
2.
Molecular Diversity - Tuberculosis (TB) is an infectious disease and the leading cause of death globally. The rapidly emerging cases of drug resistance among pathogenic mycobacteria have been a...  相似文献   
3.
Aabid  Abdul  Khan  Sher Afghan  Afzal  Asif  Baig  Muneer 《Meccanica》2022,57(1):17-42
Meccanica - The present research focuses on dynamic flow control management using tiny jets with three combinations; the first one located at 90° intervals of the base, the second one located...  相似文献   
4.
5.
Novel functionalized graphene adsorbent was prepared and characterized using different techniques. The prepared adsorbent was applied for the removal of cadmium ions from aqueous solution. A response surface methodology was used to evaluate the simple and combined effects of the various parameters, including adsorbent dosage, pH, and initial concentration. Under the optimal conditions, the cadmium removal performance of 70% was achieved. A good agreement between experimental and predicted data in this study was observed. The experimental results revealed of cadmium adsorption with high linearity follow Langmuir isotherm model with maximum adsorption capacity of 502 mg g?1, and the adsorption data fitted well into pseudo‐second order model. Thermodynamic studies showed that adsorption process has exothermic and spontaneous nature. The recommended optimum conditions are: cadmium concentration of 970 mg L?1, adsorbent dosage of 1 g L?1, pH of 6.18, and T = 25 °C. The magnetic recovery of the adsorbent was performed using a magnetic surfactant to form a noncovalent magnetic functionalized graphene. After magnetic recovery of the adsorbent both components (adsorbent and magnetic surfactant) were recycled by tuning the surface charges through changing the pH of the solution. Desorption behavior studied using HNO3 solution indicated that the adsorbent had the potential for reusability.  相似文献   
6.
7.

This article studies buoyancy-driven natural convection of a nanofluid affected by a magnetic field within a square enclosure with an individual conductive pin fin. The effects of electromagnetic forces, thermal conductivity, and inclination angle of pin fin were investigated using non-dimensional parameters. An extensive sensitivity analysis was conducted seeking an optimal heat transfer setting. The novelty of this work lies in including different contributing factors in heat transfer analysis, rigorous analysis of design parameters, and comprehensive mathematical analysis of solution domain for optimization. Results showed that magnetic strength diminished the heat transfer efficacy, while higher relative thermal conductivity of pin fin improved it. Based on the problem settings, we also obtained the relative conductivity value in which the heat transfer is optimal. Higher sensitivity of heat transfer was, though, noticed for both magnetic strength and fin thermal conductivity in comparison to fin inclination angle. Further studies, specifically with realistic geometrical configurations and heat transfer settings, are urged to translate current findings to industrial applications.

  相似文献   
8.
Journal of Applied Spectroscopy - With the COVID-19 outbreak, many challenges are posed before the scientific world to curb this pandemic. The diagnostic testing, treatment, and vaccine development...  相似文献   
9.
A temperature control unit was implemented to vary the temperature of samples studied on a commercial Mobile Universal Surface Explorer nuclear magnetic resonance (MOUSE-NMR) apparatus. The device was miniaturized to fit the maximum MOUSE sampling depth (25 mm). It was constituted by a sample holder sandwiched between two heat exchangers placed below and above the sample. Air was chosen as the fluid to control the temperature at the bottom of the sample, at the interface between the NMR probe and the sample holder, in order to gain space. The upper surface of the sample was regulated by the circulation of water inside a second heat exchanger placed above the sample holder. The feasibility of using such a device was demonstrated first on pure water and then on several samples of bread dough with different water contents. For this, T1 relaxation times were measured at various temperatures and depths and were then compared with those acquired with a conventional compact closed-magnet spectrometer. Discussion of results was based on biochemical transformations in bread dough (starch gelatinization and gluten heat denaturation). It was demonstrated that, within a certain water level range, and because of the low magnetic field strength of the MOUSE, a linear relationship could be established between T1 relaxation times and the local temperature in the dough sample.  相似文献   
10.
A series of new substituted benzimidazoles embedded with a variety of function groups has been synthesized from N‐methyl‐2‐bromoacetylbenzimidazole. The synthesized compounds were fully characterized, and their structures were elucidated based on elemental analysis, spectral data, and alternative synthetic pathways, whenever possible. Some of benzimidazole derivatives were tested as corrosion inhibitors.  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