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   1699篇
  免费   139篇
  国内免费   154篇
  2023年   26篇
  2022年   24篇
  2021年   29篇
  2020年   51篇
  2019年   40篇
  2018年   55篇
  2017年   45篇
  2016年   47篇
  2015年   61篇
  2014年   68篇
  2013年   88篇
  2012年   55篇
  2011年   75篇
  2010年   66篇
  2009年   92篇
  2008年   100篇
  2007年   95篇
  2006年   93篇
  2005年   61篇
  2004年   72篇
  2003年   61篇
  2002年   57篇
  2001年   38篇
  2000年   34篇
  1999年   33篇
  1998年   39篇
  1997年   30篇
  1996年   39篇
  1995年   35篇
  1994年   36篇
  1993年   43篇
  1992年   45篇
  1991年   36篇
  1990年   32篇
  1989年   23篇
  1988年   16篇
  1987年   19篇
  1986年   16篇
  1985年   27篇
  1984年   14篇
  1983年   9篇
  1982年   14篇
  1981年   11篇
  1980年   4篇
  1979年   6篇
  1978年   5篇
  1977年   4篇
  1976年   9篇
  1975年   4篇
  1974年   3篇
排序方式: 共有1992条查询结果,搜索用时 15 毫秒
1.
Both leica microscopic camera system and scanning electron microscopy was used to observe and characterize the feet, back, abdomen, antennae and mouthparts of the Pseudoregma bambucicola from the bamboo, Bambusa multiplex. The possible functions of all the external morphological characteristics of the P. bambucicola were described and discussed in detail, which offers a basis for further enriching the biology, phylogeny and ecological niche of the P. bambucicola. Moreover, the morphological results should contribute to morphological identification and differentiation of the P. bambucicola from other aphids in the same family.  相似文献   
2.
3.
A morphological mutation particularly detectable in the dikaryotic state was found in Lentinula edodes. The mutant dikaryon was readily distinguishable from the normal dikaryon by the irregularly branched short hyphae, very slow hyphal growth, and sparse aerial hyphae. Genetic analysis revealed that expression of this mutation was controlled by a single recessive gene, mor-13. Linkage analysis showed that the mor-13 was not linked to either the incompatibility factors (A and B) or the five kinds of mor genes that were segregated independently of each other in a previous study. Contribution no. 380 from the Tottori Mycological Institute  相似文献   
4.
The morphology of dissociated single cerebellar Purkinje cells obtained from wild-type P1 CD1 mice was assessed in the absence and in the presence of glia. A dedicated noninvasive technique based on optical microscopy was developed. Image processing algorithms were implemented to extract metrical features characterizing cell structure and dendritic arborization. The morphological features were analyzed in order to identify quantitative differences in Purkinje cell morphology due to interactions with astrocytes.  相似文献   
5.
We have analyzed dermatoglyphic finger patterns in a Spanish Basque population (841 males and 911 females). Bimanual and sexual comparisons have been carried out by means of contingency analysis. The results in the Basque population are compared with those of other Spanish populations, based on univariate (chi 2 contingency test and Student's t-test) and multivariate (principal components analyses) statistical methods. Bilateral distribution asymmetry and sexual dimorphism were observed in the Basque sample. The results of the chi 2 test for pattern types in males and females show statistically significant differences between the Basques and other Spanish populations, with the exception of the males from El Bierzo. Comparing populations with regard to the Pattern Intensity Index, the differences observed are much lower; therefore, this confirms what other authors have suggested regarding the limited usefulness of indexes in populational comparisons. In the Caucasian variation range of pattern types, Basques are located in the high part with regard to arches, in the low part with regard to whorls and radial loops, and in an intermediate part in relation to ulnar loops and overall pattern intensity. Results of the multivariate comparisons show which populations are more or less distant from the Basque population and which variables are significant in contributing to these population relationships.  相似文献   
6.
7.
The first international comparison test on swine lymphocyte alloantigens (SLA) was held in Helsinki, Finland in July 1986. The results reported were based on a comparison of 157 alloantisera originating from six laboratories. The antisera were tested against a selected panel of 264 lymphocyte samples belonging to four laboratories. The most common breeds in Europe were chosen for this first comparison test (Landrace and Large White). Eighteen of the 31 previously known specificities were confirmed and a new nomenclature was established.  相似文献   
8.
9.
Primary cell cultures were prepared from breast muscles of 11 day 4 hour-embryonic chicks. Cytoplasmic RNAs were isolated from the cultured cells at various time intervals from day 3 to day 8. A [P32] DNA probe complementary to messenger RNA of myosin heavy chain was used to hybridize with the RNAs after gel electrophoresis. A transient species of polyadenylated RNA with a decreased mobility in electrophoresis was detected during a period of time when contractions of syncytial fibers were first observed.  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