全文获取类型
收费全文 | 534篇 |
免费 | 51篇 |
国内免费 | 181篇 |
专业分类
766篇 |
出版年
2024年 | 8篇 |
2023年 | 22篇 |
2022年 | 21篇 |
2021年 | 28篇 |
2020年 | 23篇 |
2019年 | 38篇 |
2018年 | 22篇 |
2017年 | 23篇 |
2016年 | 16篇 |
2015年 | 26篇 |
2014年 | 35篇 |
2013年 | 54篇 |
2012年 | 35篇 |
2011年 | 58篇 |
2010年 | 33篇 |
2009年 | 32篇 |
2008年 | 26篇 |
2007年 | 34篇 |
2006年 | 36篇 |
2005年 | 29篇 |
2004年 | 30篇 |
2003年 | 14篇 |
2002年 | 13篇 |
2001年 | 19篇 |
2000年 | 7篇 |
1999年 | 12篇 |
1998年 | 7篇 |
1997年 | 8篇 |
1996年 | 5篇 |
1995年 | 3篇 |
1994年 | 1篇 |
1993年 | 2篇 |
1992年 | 6篇 |
1991年 | 2篇 |
1990年 | 4篇 |
1989年 | 5篇 |
1988年 | 2篇 |
1986年 | 3篇 |
1985年 | 3篇 |
1984年 | 3篇 |
1983年 | 3篇 |
1982年 | 5篇 |
1981年 | 3篇 |
1980年 | 2篇 |
1979年 | 3篇 |
1978年 | 1篇 |
1976年 | 1篇 |
排序方式: 共有766条查询结果,搜索用时 0 毫秒
101.
102.
103.
Dr. Hans-Hermann Schmidt 《Archives Of Phytopathology And Plant Protection》2013,46(4):321-322
Information on the structure of the population of Phomopsis species in Ukraine, that describes the structure of Phomopsis spp. cultivated on medium: the morfological characteristics, properties of pathogenicity and phytotoxicity. It is described the method of evaluation and selection of unsusceptible forms of sunflower to phomopsis. It includes the optimal infection level, the forms of an inoculum that is effective and optimal way for artificial infection. 相似文献
104.
辽宁省菜田生态系统组分优势值与系统优势度分析 总被引:2,自引:1,他引:1
辽宁省菜田生态系统组分优势值与系统优势度分析周宝利,葛晓光李宁义(沈阳农业大学园艺系,110161)(沈阳市城建中专,110013)AnalysisonSuperiorityValueandDominanceDegreeofVariousCompon... 相似文献
105.
Ecological processes that can realistically account for network architectures are central to our understanding of how species assemble and function in ecosystems. Consumer species are constantly selecting and adjusting which resource species are to be exploited in an antagonistic network. Here we incorporate a hybrid behavioural rule of adaptive interaction switching and random drift into a bipartite network model. Predictions are insensitive to the model parameters and the initial network structures, and agree extremely well with the observed levels of modularity, nestedness and node-degree distributions for 61 real networks. Evolutionary and community assemblage histories only indirectly affect network structure by defining the size and complexity of ecological networks, whereas adaptive interaction switching and random drift carve out the details of network architecture at the faster ecological time scale. The hybrid behavioural rule of both adaptation and drift could well be the key processes for structure emergence in real ecological networks. 相似文献
106.
Tomas Laursen Solomon H. Stonebloom Venkataramana R. Pidatala Devon S. Birdseye Mads H. Clausen Jenny C. Mortimer Henrik Vibe Scheller 《The Plant journal : for cell and molecular biology》2018,94(2):340-351
Pectins are the most complex polysaccharides of the plant cell wall. Based on the number of methylations, acetylations and glycosidic linkages present in their structures, it is estimated that up to 67 transferase activities are involved in pectin biosynthesis. Pectic galactans constitute a major part of pectin in the form of side‐chains of rhamnogalacturonan‐I. In Arabidopsis, galactan synthase 1 (GALS1) catalyzes the addition of galactose units from UDP‐Gal to growing β‐1,4‐galactan chains. However, the mechanisms for obtaining varying degrees of polymerization remain poorly understood. In this study, we show that AtGALS1 is bifunctional, catalyzing both the transfer of galactose from UDP‐α‐d ‐Gal and the transfer of an arabinopyranose from UDP‐β‐l ‐Arap to galactan chains. The two substrates share a similar structure, but UDP‐α‐d ‐Gal is the preferred substrate, with a 10‐fold higher affinity. Transfer of Arap to galactan prevents further addition of galactose residues, resulting in a lower degree of polymerization. We show that this dual activity occurs both in vitro and in vivo. The herein described bifunctionality of AtGALS1 may suggest that plants can produce the incredible structural diversity of polysaccharides without a dedicated glycosyltransferase for each glycosidic linkage. 相似文献
107.
Peng Xi Yan Li Xiaojin Ge Dandan Liu Mingsan Miao 《Saudi Journal of Biological Sciences》2018,25(4):797-800
Objective
Observing the effect of nano-silver hydrogel coating film on deep partial thickness scald model of rabbit.Method
We prepared boiling water scalded rabbits with deep II degree scald models and applied high, medium and low doses of nano-silver hydrogel coating film for different time and area. Then we compared the difference of burned paper weight before administration and after administration model burns, burn local skin irritation points infection, skin crusting and scabs from the time, and the impact of local skin tissue morphology.Result
Rabbits deep II degree burn model successful modeling; on day 12, 18, high, medium and low doses of nano-silver hydrogel coating film significantly reduced skin irritation of rabbits infected with the integral value (P < 0.01, P < 0.05); high, medium and low doses of nano-silver hydrogel coating film group significantly decreased skin irritation, infection integral value (P < 0.01, P < 0.05); high, medium and low doses of nano-silver hydrogel coating film significantly reduced film rabbits’ scalded skin crusting time (P < 0.01), significantly shortened the rabbit skin burns from the scab time (P < 0.01), and significantly improved the treatment of skin diseases in rabbits scald model change (P < 0.01, P < 0.05).Conclusion
The nano-silver hydrogel coating film on the deep partial thickness burns has a significant therapeutic effect; external use has a significant role in wound healing. 相似文献108.
109.
110.
Previous work documented seasonal field response dynamics of Euschistus conspersus Uhler (Heteroptera: Pentatomidae) to Euschistus spp. pheromone [methyl (2E,4Z)‐decadienoate]‐baited traps in California processing tomatoes, Lycopersicon esculentum (Miller) (Solanaceae). A laboratory phenology model has been reported for E. conspersus egg incubation to adult emergence. In the present work, reproductive and thoracic dissections were performed on female E. conspersus collected year‐round from seasonal habitats in California's Central Valley. We used these dissection data to establish relationships between the morphology of E. conspersus and time of year, habitat, sample recovery method, and female attraction to pheromone traps in commercial tomato fields. All ovariole categories, sexually immature through postreproductive, were recorded for females collected from tomatoes by plant‐beating sample throughout the growing season. Conversely, pheromone trap captures in tomatoes over the same period revealed that females entering the traps were exclusively reproductively active with matured eggs. We conclude that early season female‐biased E. conspersus pheromone trap catch can be used to establish a ‘biofix’ from which to accumulate degree days and forecast nymphal development in the field. Focusing control efforts on the more susceptible nymph stages may improve efficacy of reduced‐risk insecticides such as the neonicotinoids. Thoracic dissection results, with no significant difference in flight muscle size or color by ovariole condition, failed to support our hypothesis of a life history trade‐off between female reproductive activity and flight capability to explain a decline in female pheromone trap response during the mid‐summer tomato‐fruiting stages. The adaptive value of the observed retention of E. conspersus flight capability over the calendar year, and across reproductive stages, is discussed. 相似文献