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   11801篇
  免费   694篇
  国内免费   34篇
  12529篇
  2024年   34篇
  2023年   132篇
  2022年   419篇
  2021年   625篇
  2020年   374篇
  2019年   502篇
  2018年   555篇
  2017年   384篇
  2016年   538篇
  2015年   596篇
  2014年   700篇
  2013年   923篇
  2012年   935篇
  2011年   821篇
  2010年   502篇
  2009年   406篇
  2008年   497篇
  2007年   497篇
  2006年   433篇
  2005年   433篇
  2004年   352篇
  2003年   293篇
  2002年   260篇
  2001年   122篇
  2000年   109篇
  1999年   88篇
  1998年   66篇
  1997年   33篇
  1996年   49篇
  1995年   44篇
  1994年   31篇
  1993年   31篇
  1992年   54篇
  1991年   45篇
  1990年   55篇
  1989年   45篇
  1988年   49篇
  1987年   40篇
  1986年   36篇
  1985年   46篇
  1984年   41篇
  1983年   31篇
  1982年   24篇
  1981年   31篇
  1980年   20篇
  1979年   22篇
  1978年   25篇
  1977年   22篇
  1976年   26篇
  1975年   19篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
1.
2.
3.
4.
The morphology and innervation of the six oculomotor muscles in the gobiid fishTridentiger trigonocephalus are described. Every rectus muscle is composed of two types of muscle fibres. Muscles attach onto the cartilaginous or fibrous sclerotica. Oblique muscles attach onto the ethmoidal plate; recti muscles attach onto the parasphenoid or a thick fibrous membrane. There is no myodome. The common oculomotor nerve is composed of four bundles, the trochlear and the externus of two. The two kinds of fibres of the lateral rectus and the two distinct bundles of the nerve VI suggest a possible homology between this muscle in fishes and the lateral rectus+retractor bulbi in mammals.  相似文献   
5.
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.
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   
8.
The aim of this investigation was to evaluate the semen quality traits of purebred male rabbits and their crosses under subtropical Egyptian conditions. A full 3 x 3 diallel crossing was performed for producing the first generation progeny of New Zealand White (N), Flander (F) and Rex (R) breeds. The highest ejaculate volume (p< 0.05) and percentage of live sperms (p<0.01) with the lowest percentage of sperm cell morphological abnormalities (p<0.05) had been recorded in the NF bucks. Moreover, they possessed positive estimates of direct heterosis for ejaculate volume, mass motility (Mm), individual motility (Im) and sperm cell concentration (SCC). On the contrary, pH had negative estimates of direct heterosis in all crosses and their reciprocal. Semen pH was negatively correlated with SCC (r = -0.18), Mm (r = -0.13) and Im (r = -0.23). In conclusion, the superiority of crossbreeding was particularly obvious in the New Zealand White x Flander males, which cumulated heterosis and favorable maternal effects of the Flander dams.  相似文献   
9.
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