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   15618篇
  免费   1010篇
  国内免费   381篇
  2024年   24篇
  2023年   166篇
  2022年   240篇
  2021年   815篇
  2020年   529篇
  2019年   648篇
  2018年   669篇
  2017年   512篇
  2016年   743篇
  2015年   882篇
  2014年   1073篇
  2013年   1245篇
  2012年   1321篇
  2011年   1150篇
  2010年   699篇
  2009年   578篇
  2008年   717篇
  2007年   673篇
  2006年   561篇
  2005年   512篇
  2004年   435篇
  2003年   375篇
  2002年   339篇
  2001年   208篇
  2000年   187篇
  1999年   172篇
  1998年   123篇
  1997年   92篇
  1996年   75篇
  1995年   92篇
  1994年   81篇
  1993年   81篇
  1992年   114篇
  1991年   90篇
  1990年   80篇
  1989年   71篇
  1988年   72篇
  1987年   49篇
  1986年   44篇
  1985年   59篇
  1984年   45篇
  1983年   38篇
  1982年   31篇
  1981年   33篇
  1980年   20篇
  1979年   34篇
  1978年   27篇
  1977年   19篇
  1976年   29篇
  1975年   22篇
排序方式: 共有10000条查询结果,搜索用时 843 毫秒
1.
2.
3.
4.
5.
  相似文献   
6.
Perspective texture synthesis has great significance in many fields like video editing, scene capturing etc., due to its ability to read and control global feature information. In this paper, we present a novel example-based, specifically energy optimization-based algorithm, to synthesize perspective textures. Energy optimization technique is a pixel-based approach, so it’s time-consuming. We improve it from two aspects with the purpose of achieving faster synthesis and high quality. Firstly, we change this pixel-based technique by replacing the pixel computation with a little patch. Secondly, we present a novel technique to accelerate searching nearest neighborhoods in energy optimization. Using k- means clustering technique to build a search tree to accelerate the search. Hence, we make use of principal component analysis (PCA) technique to reduce dimensions of input vectors. The high quality results prove that our approach is feasible. Besides, our proposed algorithm needs shorter time relative to other similar methods.  相似文献   
7.
Guo  Jianxiu  Bowatte  Saman  Hou  Fujiang 《Plant and Soil》2021,459(1-2):49-63
Plant and Soil - Seeds are involved in the transmission of microorganisms from one plant generation to the next, acting as initial inoculum for the plant microbiome, therefore provide a key source...  相似文献   
8.
One novel approach for the biological delivery of peptide drugs is to incorporate the sequence of the peptide into the structure of a natural transport protein such as human serum transferrin (HST). However, a potential drawback is that the HST may increase the immunoreactivity of the peptide, in the same way that carrier proteins can be used to generate highly immunogenic peptide hapten conjugates. In this study we have generated a recombinant HST carrier protein that contains a peptide substrate of HIV-1 protease (VSQNYPIVL). The protein retained native HST function, and the peptide was surface exposed since it was immunoreactive in native dot blots, and was cleaved by HIV-1 protease. Immunisation of rabbits with the recombinant protein elicited only a very poor anti-peptide immune response. In contrast, strong anti-peptide immune responses were raised against both the peptide alone, and a chemical conjugate of the peptide with HST. These data demonstrate that it is possible to attenuate the immune response normally directed against an immunogenic peptide sequence by engineering into a surface exposed loop of HST. These findings may have an important impact on the future design of peptide delivery systems.  相似文献   
9.
  1. As a highly endangered species, the giant panda (panda) has attracted significant attention in the past decades. Considerable efforts have been put on panda conservation and reproduction, offering the promising outcome of maintaining the population size of pandas. To evaluate the effectiveness of conservation and management strategies, recognizing individual pandas is critical. However, it remains a challenging task because the existing methods, such as traditional tracking method, discrimination method based on footprint identification, and molecular biology method, are invasive, inaccurate, expensive, or challenging to perform. The advances of imaging technologies have led to the wide applications of digital images and videos in panda conservation and management, which makes it possible for individual panda recognition in a noninvasive manner by using image‐based panda face recognition method.
  2. In recent years, deep learning has achieved great success in the field of computer vision and pattern recognition. For panda face recognition, a fully automatic deep learning algorithm which consists of a sequence of deep neural networks (DNNs) used for panda face detection, segmentation, alignment, and identity prediction is developed in this study. To develop and evaluate the algorithm, the largest panda image dataset containing 6,441 images from 218 different pandas, which is 39.78% of captive pandas in the world, is established.
  3. The algorithm achieved 96.27% accuracy in panda recognition and 100% accuracy in detection.
  4. This study shows that panda faces can be used for panda recognition. It enables the use of the cameras installed in their habitat for monitoring their population and behavior. This noninvasive approach is much more cost‐effective than the approaches used in the previous panda surveys.
  相似文献   
10.
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