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   152篇
  免费   17篇
  169篇
  2013年   3篇
  2012年   4篇
  2011年   7篇
  2010年   5篇
  2009年   6篇
  2008年   4篇
  2007年   4篇
  2006年   4篇
  2005年   2篇
  2004年   2篇
  1998年   2篇
  1997年   2篇
  1996年   5篇
  1993年   2篇
  1991年   3篇
  1990年   2篇
  1989年   2篇
  1988年   2篇
  1987年   3篇
  1986年   2篇
  1984年   3篇
  1983年   2篇
  1981年   2篇
  1980年   4篇
  1979年   3篇
  1978年   2篇
  1976年   2篇
  1975年   2篇
  1974年   4篇
  1971年   5篇
  1970年   3篇
  1967年   1篇
  1966年   1篇
  1963年   1篇
  1962年   1篇
  1961年   1篇
  1960年   1篇
  1959年   4篇
  1958年   2篇
  1957年   7篇
  1956年   10篇
  1955年   3篇
  1954年   13篇
  1953年   2篇
  1952年   6篇
  1951年   2篇
  1950年   1篇
  1949年   1篇
  1948年   1篇
  1924年   1篇
排序方式: 共有169条查询结果,搜索用时 0 毫秒
81.
82.
83.
84.
The glandular trichomes ofFagoniaconsist of one secretory celland a multicellular stalk, which develops by division, elongationand elevation of epidermal cells. The latter become seperatedfrom the mesophyll and a subepidermal chamber is formed. Thelength of the stalk, which differs in the various species orvarieties is determined by the number of cell divisions and/or the extent of cell elongation. Although the basic morphologyand development of the trichomes of the species and varietiesexamined are similar, two types of mature trichomes can be distinguished:one occurs in the two examined varieties ofF. mollisand thesecond inF. glutinosaandF. arabica. The secretory cells of thesecond type possess a very thick wall and bear a porous cupuleon their top. Histochemical tests revealed that the sticky substancesecreted by the secretory cells contains mainly polysaccharidesand lipophilic compounds. The secreted material exhibits autofluorescence.InF. mollisvar.hispidachanges in the amount and shape of thefluorescent material inside the secretory cell, during the courseof development, have been observed. The contribution of theglandular trichomes inFagoniaspecies to survival in hot desertconditions is discussed. Fagonia; glandular trichomes; subepidermal chamber; secreted material; adaptation to desert conditions; stalk; fluorescence  相似文献   
85.
Movement of 14C-assimilates from young and mature leaves to young rose shoots (Rosa hybrida cv. Marimba) was examined in two developmental stages. In the first stage after bud breaking the young shoot, especially its tip, depends for its supply of assimilates mainly on the mature foliage. At this stage young leaves are powerful sinks and retain 97% of their own photosynthates. The translocated 3% move mainly to the roots. At a later stage, just after the appearance of the flower bud, most of the leaves on the shoot become a source. The upper leaves supply assimilates to the flower bud and to the upper part of the stem. The 14C-assimilates from the lower leaves move in two directions, the larger part being directed downward.  相似文献   
86.
Following a discussion of the rationale underlying the selection of human melanoma to test the usefulness of anti-idiotypic monoclonal antibodies in the therapy of solid tumors, the development of the anti-idiotypic monoclonal antibody MoAb) MF11–30 is described. This antibody recognizes a private idiotope within the antigen-combining site of the immunizing antihuman high molecular weight melanoma-associated antigen MoAb 225.28. The results of a phase I clinical trial with the MoAb MF11–30 in patients with advanced melanoma are described. The lack of toxic effects and the minor responses in six patients suggest that these studies should be extended to a larger number of patients with an emphasis on the analysis of the mechanisms underlying the clinical response.  相似文献   
87.
88.
89.
90.
Single node explants of ‘Baccara’ rose were fed through the basal cut surface with 14C-sucrose in agar. Accumulation of 14C-metabolites by buds is a steady process, while a quick uptake occurs in the stem piece during the initial stage of incubation suggesting a passive uptake at this stage. The uppermost 5-leaflet node buds had an initially higher 14C-uptake than the lowest bud. This difference disappeared after 2–3 days when growth started in both buds. Light enhanced uptake of 14C-sucrose by both stem pieces and buds. Accumulation of 14C-metabolites by buds was in direct relationship to buds deviation from the direction of gravity. This phenomenon was not evident in the stem part of the explant.  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