全文获取类型
收费全文 | 271619篇 |
免费 | 25860篇 |
国内免费 | 256篇 |
出版年
2018年 | 2905篇 |
2017年 | 2817篇 |
2016年 | 3869篇 |
2015年 | 4362篇 |
2014年 | 5358篇 |
2013年 | 7537篇 |
2012年 | 8410篇 |
2011年 | 9012篇 |
2010年 | 6099篇 |
2009年 | 5471篇 |
2008年 | 7882篇 |
2007年 | 8091篇 |
2006年 | 7652篇 |
2005年 | 7311篇 |
2004年 | 7194篇 |
2003年 | 7028篇 |
2002年 | 6865篇 |
2001年 | 12790篇 |
2000年 | 12746篇 |
1999年 | 9822篇 |
1998年 | 3053篇 |
1997年 | 3090篇 |
1996年 | 3021篇 |
1995年 | 2771篇 |
1994年 | 2723篇 |
1993年 | 2630篇 |
1992年 | 7792篇 |
1991年 | 7545篇 |
1990年 | 7602篇 |
1989年 | 7438篇 |
1988年 | 6872篇 |
1987年 | 6570篇 |
1986年 | 5788篇 |
1985年 | 6180篇 |
1984年 | 4909篇 |
1983年 | 4216篇 |
1982年 | 3037篇 |
1981年 | 2832篇 |
1980年 | 2599篇 |
1979年 | 4497篇 |
1978年 | 3493篇 |
1977年 | 3190篇 |
1976年 | 3114篇 |
1975年 | 3579篇 |
1974年 | 3844篇 |
1973年 | 3852篇 |
1972年 | 3350篇 |
1971年 | 3105篇 |
1970年 | 2749篇 |
1969年 | 2527篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
951.
Ethnobotanical review of wild edible plants in Spain 总被引:5,自引:0,他引:5
JAVIER TARDÍO MANUEL PARDO-DE-SANTAYANA RAMÓN MORALES 《Botanical journal of the Linnean Society. Linnean Society of London》2006,152(1):27-71
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 Forty-six ethnobotanical and ethnographical sources from Spain were reviewed, together with some original unpublished field data from several Spanish provinces.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
952.
953.
954.
955.
956.
957.
958.
959.
N R Krieg 《Canadian journal of microbiology》1988,34(4):536-540
Classification of bacteria evolved from limited subjective groupings to general, more objective arrangements based on overall phenotypic similarities. However, classifications based on phenotypic characters lack stability, whereas those based on genetic relatedness tend to be stable. DNA-DNA hybridization has proven to be extremely useful in resolving taxonomic problems at the species level. Broad relationships among bacteria have been identified by comparing ribosomal RNA cistrons; however, many groups based on ribosomal RNA analysis are not easily definable in terms of phenotypic similarities. Unless resolved, these problems could lead to the establishment of two separate classification systems, one phylogenetic and the other practical. 相似文献
960.
Using fluorimetric and polarographic determination of cell respiration, metabolic reactions of the carotid body of rats to adequate stimulation have been revealed. Functional relationships of the dose--effect type, which were found for these reactions, may be approximated by equations which are similar to those describing the unconditioned reflexes from the carotid chemoreceptors. However, reactions of the metabolics systems of the carotid body account for the perception of not all chemical stimuli, but only of acids and some alkaloids. These data reveal the heteregeneity of the carotid chemosensory system not only in the amphibians (which was known earlier), but in mammals as well. 相似文献