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   1239篇
  免费   95篇
  国内免费   2篇
  2023年   14篇
  2022年   19篇
  2021年   51篇
  2020年   29篇
  2019年   31篇
  2018年   35篇
  2017年   44篇
  2016年   54篇
  2015年   63篇
  2014年   66篇
  2013年   127篇
  2012年   110篇
  2011年   96篇
  2010年   57篇
  2009年   39篇
  2008年   64篇
  2007年   39篇
  2006年   50篇
  2005年   52篇
  2004年   38篇
  2003年   26篇
  2002年   22篇
  2001年   17篇
  2000年   11篇
  1999年   16篇
  1998年   8篇
  1997年   4篇
  1995年   5篇
  1992年   6篇
  1991年   4篇
  1990年   7篇
  1989年   8篇
  1988年   8篇
  1987年   5篇
  1986年   8篇
  1985年   8篇
  1984年   4篇
  1983年   8篇
  1982年   5篇
  1981年   6篇
  1980年   11篇
  1979年   10篇
  1977年   4篇
  1975年   3篇
  1974年   4篇
  1973年   5篇
  1971年   5篇
  1970年   3篇
  1969年   6篇
  1966年   4篇
排序方式: 共有1336条查询结果,搜索用时 31 毫秒
21.
22.
23.
During the survey of two successive years 2012–2013, in nearby places of Gorakhpur districts, Uttar Pradesh, India, Arundo donax plants were found to be exhibiting witches’ broom, excessive branching accompanied with little leaf symptoms with considerable disease incidence. Nested PCR carried out with universal primers pair R16F2n/R16R2 employing the PCR (P1/P7) product as a template DNA (1:20) resulted in expected size positive amplification ~1.2 kb in all symptom-bearing plants suggested the association of phytoplasma with witches’ broom disease of Narkat plants. BLASTn analysis of the 16S rRNA gene sequence showed the highest (99%) sequence identity with Candidatus phytoplasma asteris (16SrI group). In phylogenetic analysis, the sequence data showed close relationships with the members of 16SrI phytoplasma and clustered within a single clade of 16SrI group and closed to B subgroup representatives. This is a first report of 16Sr I-B group phytoplasma associated with witches’ broom accompanied with little leaf disease of Narkat in India.  相似文献   
24.
25.
Journal of Plant Biochemistry and Biotechnology - Pigeonpea, an important legume crop is a good host plant for lac cultivation in North East India. In the present study, sixty-three polymorphic EST...  相似文献   
26.
Journal of Plant Biochemistry and Biotechnology - Caseinolytic protease (Clp)/Hsp100 proteins are members of the AAA+ (ATPase associated with a variety of cellular activities) family of proteins...  相似文献   
27.
Archives of Microbiology - Biofilms are structured microbial communities of single or multiple populations in which microbial cells adhere to a surface and get embedded in extracellular polymeric...  相似文献   
28.

Riparian zones are among the most valuable ecosystems on the earth. They act as the ecological engineers that improve river health through delivering a range of ecosystem functions. Stream bank stabilization, pollutant and sediment buffering, temperature regulation, provision of energy to river food webs and communities, groundwater recharge and provision of ecological corridors and habitat for wildlife, are among major ecosystem functions of riparian zones that play a great role in river health. Besides these ecosystem functions, riparian zones also provide various ecosystem goods and services for human well-being. But in the current scenario, riparian zones are under severe threat due to agricultural activities, urbanization, river flow alteration, overexploitation, climate change, pollution, and biological invasion. In the present and probable future scenarios of declining river health and global environmental changes, there is a pressing need of an integrated approach for managing riparian zones. This review article aims to advocate an integrated approach for riparian zone management based on various components such as riparian condition assessment, policy framework, stakeholder’s participation, management practices, legislation, and awareness. Authors also discussed riparian zones in context of their concepts, features, functions, and threats.

  相似文献   
29.
Russian Journal of Bioorganic Chemistry - 1,4-Dihydropyridinecarboxylates were prepared by the reaction of nicotinaldehydes with aminocrotonoates in the presence of p-TsOH at room temperature. The...  相似文献   
30.
When an γ‐irradiated Dy‐, Tm‐, Sm‐ or Mn‐doped CaSO4 crystal is impulsively deformed, two peaks appear in the ML intensity versus time curve, whereby the first ML peak is found in the deformation region and the second in the post‐deformation region of the crystals. In this study, intensities Im1 and Im2 corresponding to first and second ML peaks, respectively, increased linearly with an impact velocity v0 of the piston used to deform the crystals, and times tm1 and tm2 corresponding to the first and second ML peaks, respectively, decreased with impact velocity. Total ML intensity initially increased with impact velocity and then reached a saturation value for higher values of impact velocity. ML intensity increased with increasing γ‐doses and size of crystals. Results showed that the electric field produced as a result of charging of newly‐created surfaces caused tunneling of electrons to the valence band of the hole‐trapping centres. The free holes generated moved in the valence band and their subsequent recombination with electron trapping centres released energy, thereby resulting in excitation of luminescent centres. Copyright © 2012 John Wiley & Sons, Ltd.  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