全文获取类型
收费全文 | 5146篇 |
免费 | 81篇 |
国内免费 | 144篇 |
专业分类
教育 | 3409篇 |
科学研究 | 710篇 |
体育 | 600篇 |
综合类 | 444篇 |
文化理论 | 5篇 |
信息传播 | 203篇 |
出版年
2024年 | 1篇 |
2023年 | 2篇 |
2022年 | 26篇 |
2021年 | 62篇 |
2020年 | 70篇 |
2019年 | 69篇 |
2018年 | 57篇 |
2017年 | 67篇 |
2016年 | 95篇 |
2015年 | 114篇 |
2014年 | 300篇 |
2013年 | 395篇 |
2012年 | 400篇 |
2011年 | 434篇 |
2010年 | 299篇 |
2009年 | 262篇 |
2008年 | 312篇 |
2007年 | 379篇 |
2006年 | 307篇 |
2005年 | 348篇 |
2004年 | 288篇 |
2003年 | 260篇 |
2002年 | 212篇 |
2001年 | 147篇 |
2000年 | 133篇 |
1999年 | 87篇 |
1998年 | 46篇 |
1997年 | 44篇 |
1996年 | 37篇 |
1995年 | 25篇 |
1994年 | 26篇 |
1993年 | 14篇 |
1992年 | 20篇 |
1991年 | 9篇 |
1990年 | 11篇 |
1989年 | 8篇 |
1988年 | 4篇 |
1987年 | 1篇 |
排序方式: 共有5371条查询结果,搜索用时 15 毫秒
951.
国有商业银行如何应对利率市场化改革的风险 总被引:1,自引:0,他引:1
利率市场化改革给国有商业银行的经营带来更大的风险,如:竞争风险、信用风险、利率风险、流动性风险等。如何趋利避害,应对风险,笔者认为从4个方面入手:产权制度改革;经营观念的转变;业务上由传统业务向中间业务、表外业务转变,由分业经营向混业经营转变;风险的全面管理。 相似文献
952.
Frame skipping in low bit video coding could significantly reduce the visual quality of reconstructed video. At the same time, if the complexity of the video sequence remains high for a long period, then driving up the long term average bit rate, the only resort of MPEG-4 Q2 rate control algorithm results in using a high quantization scale, which shows a poor visual quality of the reconstructed video. This paper analyzes the main causes of frame skipping in current MPEG-4 frame rate control scheme, and presents a new rate control algorithm based on the quadratic R-D model over a CBR channel. Key features of the present work are. 1) the bits allocated to each P-frame or B-frame are in proportion to its distance from the end of this GOP, i.e. more bits are allocated to the frames that are nearer to their reference Ⅰ -frame: 2) the target buffer level is changeable in the GOP, at the end of each GOP( five P-frames or B-frames), the target buffer level is linearly reduced from 1/2 to 1/4 of buffer size, to other frames, the target buffer level is set to 1/2 of buffer size: 3 ) a selective and judicious use of the reduced resolution mode, in addition to a modulation of the quantization scale parameter, is to control the average long term bit rate. Experimental results with different video sequences of varied complexity, encoded at low bit rates show better efficacy of the proposed algorithm than MPEG-4 Q2 rate control scheme, and the experimental results also show that the improved algorithm has significantly reduced the number of frame skipping, increased the overall PSNR, and improved the perceptual quality. 相似文献
953.
7-二乙氨基-4-甲基香豆素(DAMC)在聚合物溶液中,荧光量子效率(φf)在非极性溶剂中与聚合物的含量无关;在极性溶剂中随聚合物的含量增加而增大,即与体系的粘度有关。在各种介质中,φf与辐射和非辐射失活速率常数的变化相一致。荧光偏振随聚合物的含量增加而增大。DAMC的荧光行为与其激发态构型密切相关。 相似文献
954.
高校评教是高校教育教学管理中的重要一环。文章针对目前已有的评教系统数据源单一、数据使用不充分、教师反馈不及时、师生互动性欠佳、学生评教积极性不高等现状,提出了一个高校评教系统新框架,以评教结果的使用范围为目的,反推出评教数据来源应具备多次性和多样性。每学期多次评教,实现教师与学生的互动,促进学生评教积极性,促进教师及时改进教学方法。评教人员除了学生之外,还应包括督导专家和往届生。 相似文献
955.
应用索洛余值法对福建全省经济增长及科技进步贡献率进行测算,计算出科技进步和其他要素对经济增长的贡献份额,并对各地市的数据进行横向比较,得出福建省各地市科技进步的差距。 相似文献
956.
A new neural network based method for solving the problem of congestion control arising at the user network interface (UNI) of ATM networks is proposed in this paper. Unlike the previous methods where the coding rate for all traffic sources as controller output signals is tuned in a body, the proposed method adjusts the coding rate for only a part of the traffic sources while the remainder sources send the cells in the previous coding rate in case of occurrence of congestion. The controller output signals include the source coding rate and the percentage of the sources that send cells at the corresponding coding rate. The control methods not only minimize the cell loss rate but also guarantee the quality of information (such as voice sources) fed into the multiplexer buffer. Simulations with 150 ADPCM voice sources fed into the multiplexer buffer showed that the proposed methods have advantage over the previous methods in the aspect of the performance indices such as cell loss rate (CLR) and voice quali 相似文献
957.
张殿成 《襄樊职业技术学院学报》2003,2(2):42-43
解决好雏鸡成活率是提高养殖业生产效益的关键措施,其常规操作规程是:育雏前的准备工作、雏鸡的选择标准、育雏的温度与湿度、雏鸡的饮水、雏鸡的饲喂、雏鸡的饲养密度、育雏舍的通风换气、适宜的光照与运动、做好雏鸡防病工作、认真实施疫病防治等,其目的在于减少饲养中的损失,以提高养鸡的生产效益,促进养鸡业的发展。 相似文献
958.
959.
960.
The objective of the study is the cytocidal and inhibitory effect of energy-controllable pulse on ovarian cancer cell line SKOV3.Ovarian cancer cell suspension were treated by electric pulse with different parameters,.The inhibitory rate(IR) was assayed by modified colorimetric MTT methods,the growth curves of two test groups and one control group were also measured.and the ultrasturctureal changes were observed under electron microscopy(EM) and scan electron microscopy (SEM),It was found that the treated SKOV3 cell proliferated more slowly.IR was increased with the enhancement of pulse paramters,The ultrastructural study showed that morphological changes occured obviously.Swollen mitochondria,fracutured ridges,cytoplasmic vacuoles and membrane holes appeard in most of the processed cells,and a part of bilayer membrane was ruptured.It is indicated that irreversible electric breakdown occurred in some of the treated cells,and the electric pulse could kill cancer cell and inhibit its recovery and growth. 相似文献