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   613篇
  免费   31篇
  国内免费   32篇
化学   106篇
晶体学   4篇
力学   5篇
综合类   1篇
数学   133篇
物理学   12篇
综合类   415篇
  2024年   1篇
  2023年   4篇
  2022年   10篇
  2021年   11篇
  2020年   7篇
  2019年   13篇
  2018年   10篇
  2017年   7篇
  2016年   13篇
  2015年   9篇
  2014年   29篇
  2013年   32篇
  2012年   30篇
  2011年   40篇
  2010年   24篇
  2009年   29篇
  2008年   34篇
  2007年   40篇
  2006年   43篇
  2005年   45篇
  2004年   33篇
  2003年   29篇
  2002年   34篇
  2001年   16篇
  2000年   23篇
  1999年   16篇
  1998年   9篇
  1997年   3篇
  1996年   10篇
  1995年   13篇
  1994年   11篇
  1993年   6篇
  1992年   13篇
  1991年   6篇
  1990年   5篇
  1989年   4篇
  1988年   2篇
  1987年   7篇
  1986年   1篇
  1985年   1篇
  1984年   1篇
  1983年   1篇
  1982年   1篇
排序方式: 共有676条查询结果,搜索用时 515 毫秒
21.
Here, we present just a collection of beans (JACOB): an integrated batch‐based framework designed for the rapid development of computational chemistry applications. The framework expedites developer productivity by handling the generic infrastructure tier, and can be easily extended by user‐specific scientific code. Paradigms from enterprise software engineering were rigorously applied to create a scalable, testable, secure, and robust framework. A centralized web application is used to configure and control the operation of the framework. The application‐programming interface provides a set of generic tools for processing large‐scale noninteractive jobs (e.g., systematic studies), or for coordinating systems integration (e.g., complex workflows). The code for the JACOB framework is open sourced and is available at: www.wallerlab.org/jacob . © 2013 Wiley Periodicals, Inc.  相似文献   
22.
基于AutoIt3和VBA为自动批量批改FrontPage操作题设计一种程序框架。首先,依据FrontPage操作技能考核要求对FrontPage操作题各小题划分评分点和对应分值。然后,应用VBA实现单份FrontPage操作题的自动批改程序。最后,应用AutoIt3实现多份FrontPage操作题的自动批量批改程序。  相似文献   
23.
在对文题进行数学描述的基础上,建立求解该类问题的混合整数线性规划模型.证明问题NP 困难性并研究多项式可解子问题,进一步提出了3个启发式算法以及精确求解的分支定界算法.数值实验表明,所提出启发式算法以及分支定界算法的有效性与高效性.  相似文献   
24.
Textile and dye industries are main sources of dye bearing effluent. In present studies the anaerobic biological degradation of Acid Red 3BN dye water (AR3BNDW) and mixed dye water (MDW) for reduction of color and COD were studied in sequential batch reactor (SBR). The sludge as sources of microorganism was arranged from maize processing bio methanation wastewater treatment plant, which was acclimatized for treatment of AR3BNDW and MDW. After the acclimatization, dyes degradation were studied in SBR At optimum operation condition of hydraulics retention time (HRT) = 2.5 d, and treatment time (tR) = 16 h, AR3BNDW have gone maximum 87% color reduction of 500 mg/L dye, and 82.8% COD reduction of 380 mg/L COD. At same operating condition, 84.5% color reduction of 500 mg/L dye, and 79.42% COD reduction of 413 mg/L COD achieved for MDW. The second order Grau model was fitted well for COD and dye reductions. The kinetics parameter were evaluated for both the dye water.  相似文献   
25.
The use of flow photochemistry and its apparent superiority over batch has been reported by a number of groups in recent years. To rigorously determine whether flow does indeed have an advantage over batch, a broad range of synthetic photochemical transformations were optimized in both reactor modes and their yields and productivities compared. Surprisingly, yields were essentially identical in all comparative cases. Even more revealing was the observation that the productivity of flow reactors varied very little to that of their batch counterparts when the key reaction parameters were matched. Those with a single layer of fluorinated ethylene propylene (FEP) had an average productivity 20 % lower than that of batch, whereas three‐layer reactors were 20 % more productive. Finally, the utility of flow chemistry was demonstrated in the scale‐up of the ring‐opening reaction of a potentially explosive [1.1.1] propellane with butane‐2,3‐dione.  相似文献   
26.
A kinetic model for single-cell protein batch fermentation was developed using the numerical simultaneous integration approach of the fourth-order Runge-Kutta method. The model takes into account the effect of substrate inhibtion, maintenance energy, and cell death on the cell growth and substrate utilization during the fermentation process. The theoretical results obtained from the model compared well with the experimental data. The model was used to study the effect of the initial substrate concentration on the lag period, fermentation time, specific growth rate, population size, and cell productivity of batch fermentation. Increasing the initial substrate concentration increased the lag period and fermentation time and decreased the specific growth rate and cell yield. The growth limiting substrate concentration was 2.9 g/L, whereas the growth inhibiting substrate concentration was 69.0 g/L. Increasing the initial substrate concentration above 150 g/L significantly decreased the yeast population size.  相似文献   
27.
COD/N对亚硝酸盐型同步硝化反硝化脱氮的影响   总被引:1,自引:1,他引:0  
采用序批式活性污泥法,对人工配制的城市污水,通过控制泥龄成功实现亚硝酸盐型同步硝化反硝化,并考察了不同COD/N对亚硝酸盐型同步硝化反硝化效果的影响.试验结果显示:适宜的泥龄下,在控制适宜的pH、DO及COD:N为6.5左右的条件下,COD、氨氮和总氮的去除率分别可达90%~95%、99%左右、90%以上.因此,适宜的泥龄时,控制反应器内适宜的COD/N,可以使亚硝酸盐型同步硝化反硝化取得很好的效果.  相似文献   
28.
王爱芹  买文宁  余杰 《河南科学》2007,25(6):1052-1054
采用IC+SBR组合工艺处理高浓度抗生素废水,结果表明,抗生素废水进入IC反应器后,得到有效的水解发酵,将有机氮充分转化为氨氮,厌氧出水经过SBR反应器处理后出水氨氮质量浓度降低到30 mg/L,有时甚至在20 mg/L以下,去除率高达80%,出水水质良好.  相似文献   
29.
阐述了对太原第一热电厂原分炉计量系统改造的必要性和可行性,分析了原分炉计量系统产生误差的原因,介绍了改进原分炉计量系统的工作原理、技术方案和运行状况。  相似文献   
30.
批处理在高校计算机实验室管理中的应用   总被引:3,自引:1,他引:2  
高校计算机实验室是教学、科研的重要基地,是培养学生创新精神和实践能力的重要实践场所。根据高校计算机实验室管理情况,探讨利用批处理命令对计算机实验室进行维护的方法。用实例的方法介绍了利用批处理文件配置计算机名、IP地址、环境变量等日常管理,使计算机实验室管理更加规范、高效。  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