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   210篇
  免费   10篇
  2018年   2篇
  2017年   7篇
  2016年   2篇
  2014年   2篇
  2013年   10篇
  2012年   9篇
  2011年   9篇
  2010年   18篇
  2009年   16篇
  2008年   19篇
  2007年   14篇
  2006年   11篇
  2005年   7篇
  2004年   3篇
  2003年   6篇
  2002年   4篇
  2001年   3篇
  1999年   4篇
  1998年   3篇
  1997年   4篇
  1996年   7篇
  1994年   1篇
  1993年   6篇
  1992年   4篇
  1990年   1篇
  1989年   3篇
  1988年   4篇
  1987年   1篇
  1985年   1篇
  1984年   2篇
  1983年   1篇
  1982年   1篇
  1981年   2篇
  1980年   1篇
  1978年   1篇
  1977年   1篇
  1975年   1篇
  1972年   2篇
  1971年   1篇
  1969年   1篇
  1958年   2篇
  1957年   1篇
  1956年   3篇
  1955年   2篇
  1954年   2篇
  1953年   1篇
  1952年   2篇
  1951年   6篇
  1948年   1篇
  1947年   1篇
排序方式: 共有220条查询结果,搜索用时 31 毫秒
1.
2.
3.
4.
Ethnobotanical review of wild edible plants in Spain   总被引:5,自引:0,他引:5  
This paper compiles and evaluates the ethnobotanical data currently available on wild plants traditionally used for human consumption in Spain. Forty-six ethnobotanical and ethnographical sources from Spain were reviewed, together with some original unpublished field data from several Spanish provinces. A total of 419 plant species belonging to 67 families was recorded. A list of species, plant parts used, localization and method of consumption, and harvesting time is presented. Of the seven different food categories considered, green vegetables were the largest group, followed by plants used to prepare beverages, wild fruits, and plants used for seasoning, sweets, preservatives, and other uses. Important species according to the number of reports include: Foeniculum vulgare , Rorippa nasturtium-aquaticum , Origanum vulgare , Rubus ulmifolius , Silene vulgaris , Asparagus acutifolius , and Scolymus hispanicus . We studied data on the botanical families to which the plants in the different categories belonged, overlapping between groups and distribution of uses of the different species. Many wild food plants have also been used for medicinal purposes and some are considered to be poisonous. This review highlights the rich traditional knowledge on edible plants that has remained in rural Spain. Until recently, many wild plants were used as dietary supplements. However, most of this knowledge survives only in the memory of the elderly, and will probably disappear in a few decades.  © 2006 The Linnean Society of London, Botanical Journal of the Linnean Society , 2006, 152 , 27–71.  相似文献   
5.
In north-central Venezuela Lutzomyia gomezi and Lu. ovallesi are the main endophilic/anthropophilic species of phlebotomine sandflies implicated as vectors of cutaneous leishmaniasis (CL). Lutzomyia ovallesi has been found infected with Leishmania braziliensis (1.2%) and less often with Le. mexicana (0.07%), while Le. braziliensis infections have also been found in Lu. gomezi (0.47%). We investigated population densities of these sandflies using two sampling methods with four series of collections between January 1991 and March 1995 at El Ingenio, Miranda State. All-night outdoor collections from a Shannon trap were correlated with indoor collections from CDC light–traps by linear regression, which proved to be statistically significant for both species. Estimated numbers of female sandflies per house per night were found to be proportional to monthly precipitation (i.e. rainfall), with a lag time of seven months for Lu. ovallesi and of six months for Lu. gomezi . Predominance of Lu. ovallesi over Lu. gomezi ( c. 10 :1 ) was observed throughout the year, with the number of infected females estimated as 0.043 ± 0.047 Lu. ovallesi and 0.0085 ± 0.0124 Lu. gomezi per CDC trap per house per night (ratio ∼ 5:1). The mean rate of new CL cases per house per year and sandfly abundance were correlated by linear regression, showing a statistically significant relationship for Lu. ovallesi but not for Lu. gomezi . The negative intercept indicated that, on average, the CDC trap density exceeds 800 Lu. ovallesi females/house/year before new CL cases occur at El Ingenio.  相似文献   
6.
Ibarra-Caballero, J., Villanueva-Verduzco, C., Molina-Galan,J. and Sanchez-de-Jimenez, E. 1988. Proline accumulation asa symptom of drought stress in maize: a tissue differentiationrequirement.—J. exp. Bot. 39: 889–897. Seedlings and callus tissue of maize (Zea mays L.) were testedfor proline accumulation under drought stress. A variety froma tropical humid region, a semi-desertic variety and its improvedpopulation selected for drought stress resistance, were usedfor this study. Proline accumulation was found in green leaves of maize seedlingsunder drought stress; no correlation was found between prolineaccumulation in leaves and the variety or population tested.White tissue, callus and leaves of etiolated seedlings did notshow this response to drought stress, nor did green callus ordetached leaves (green or etiolated), even when stress causeda loss of water from leaves similar to that observed when wholeseedlings were drought-stressed. Addition of abscisic acid togreen or white tissue did not result in proline accumulation.The above data indicate that proline accumulation caused bydrought stress does not seem to be an indication of droughtstress resistance, but rather a symptom of it. For this accumulationto take place it seems that fully organized chloroplasts arerequired as well as the systemic development of the plant. Key words: Proline, maize, drought-stress  相似文献   
7.
8.
FREIRE, S. E., CRISCI, J. V. & KATINAS, L., 1993. A cladistic analysis of Nassauvia Comm. ex Juss. (Asteraceae, Mutisieae) and related genera. Nassauvia and the most closely related genera Calopappus and Triptilion from the southern Andes and Patagonia of South America, form a monophyletic group diagnosed by the following synapomorphies: cypsela trichomes single two-celled, cypsela testa with strengthened cells, pollen grains spheroidal to spheroidal-oblate, colpi membrane with sexine processes, pappus bristles two to six, and pappus deciduous. Furthermore, Nassauvia, Triptilion, and Calopappus form a group with two other Andean genera, Moscharia and Polyachyrus, diagnosed by occurrence of pseudocephalia and a reduction in the number of flowers to five, three or one. A cladistic analysis of the group was undertaken using 35 characters from morphology, anatomy, and palynology. The monophyletic terminal taxa were the 38 species of Nassauvia, the genus Triptilion, the monotypic genus Calopappus, the genus Polyachyrus, and the genus Moscharia. Character polarity was based on outgroup comparison using Cephalopappus. The analysis resulted in 223 equally parsimonious cladograms, each with 70 steps and a consistency index of 0.57. A successive weighting procedure was applied, resulting in 15 cladograms with a consistency index of 0.82. Results of the cladistic analysis support most of the current systematic classification of Nassauvia, with three exceptions: (1) Nassauvia (excluding Calopappus) is paraphyletic; (2) section Masligophorus appears to be a polyphyletic group (N. pygmaea does not cluster with the remaining species of the section); (3) section Panargyrum (without N. lagascae= section Caloptilium) appears to be a paraphyletic group. The capitula arranged in cymose conflorescences in Triptilion are regarded as a primitive condition which gave rise to all stages present in Nassauvia (conflorescence spicate, pseudocephalium, capitula solitary). The capitula arranged in pseudocephalia in Moscharia and Polyachyrus are regarded as a parallel development to the pseudocephalium found in Nassauvia. Nassauvia, subgenus Strongyloma appears as the most primitive taxon, with its spicate conflorescence, whereas section Masligophorus with its solitary capitulum is thought-derived. These results correspond well with cytological data where species of the subgenus Strongyloma have n= 11 and the species of section Masligophorus are tetraploids (n = 22).  相似文献   
9.
SYNOPSIS. The stomatogastric nervous system of decapod crustaceansis an ideal system for the study of the processes underlyingthe generation of rhythmic movements by the nervous system.In this chapter we review recent work that uses mathematicalanalyses and computer simulations to understand: 1) the roleof individual currents in controlling the activity of neurons,and 2) the effects of electrical coupling on the activity ofneuronal oscillators. The aim of this review is to highlight,for the physiologist, what these studies have taught us aboutthe organization and function of single cell and multicellularneuronal oscillators.  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