全文获取类型
收费全文 | 165篇 |
免费 | 7篇 |
国内免费 | 43篇 |
专业分类
215篇 |
出版年
2024年 | 3篇 |
2023年 | 1篇 |
2022年 | 4篇 |
2021年 | 9篇 |
2020年 | 3篇 |
2019年 | 4篇 |
2018年 | 2篇 |
2017年 | 5篇 |
2016年 | 7篇 |
2015年 | 6篇 |
2014年 | 13篇 |
2013年 | 9篇 |
2012年 | 11篇 |
2011年 | 14篇 |
2010年 | 9篇 |
2009年 | 12篇 |
2008年 | 12篇 |
2007年 | 11篇 |
2006年 | 10篇 |
2005年 | 8篇 |
2004年 | 7篇 |
2003年 | 7篇 |
2002年 | 8篇 |
2001年 | 6篇 |
2000年 | 4篇 |
1999年 | 6篇 |
1998年 | 5篇 |
1997年 | 2篇 |
1996年 | 2篇 |
1995年 | 2篇 |
1993年 | 1篇 |
1992年 | 1篇 |
1991年 | 1篇 |
1990年 | 2篇 |
1988年 | 1篇 |
1986年 | 1篇 |
1984年 | 1篇 |
1983年 | 2篇 |
1982年 | 1篇 |
1976年 | 1篇 |
1975年 | 1篇 |
排序方式: 共有215条查询结果,搜索用时 15 毫秒
1.
2.
The results of cytogenetic investigation of 14 crewmembers of "Soyuz" spacecrafts before and after 7 spaceflights are represented. No cytogenetic changes were noted at the investigated crewmembers on the first postflight day as compared to the preflight data. Possible causes of differences between the author's data and the data of foreign investigators on cytogenetic investigation of American crewmembers are discussed in the article. 相似文献
3.
4.
大中型食肉动物肇事事件导致人类与野生动物关系恶化,给生物多样性保护工作带来巨大的挑战。若尔盖湿地是我国三大湿地之一,湿地、草原分布广泛,生物多样性丰富,畜牧业发达,但近年来狼(Canis lupus)捕杀牲畜的肇事事件时有发生。为了解若尔盖野生狼肇事件的空间分布以及牧民对人-狼冲突管理的看法,本研究于2022年对若尔盖县13个乡镇83个行政村进行走访调查。结果表明:(1)多数受访者(66.0%)认为在过去5年内,若尔盖县野生狼数量有所增加;(2)狼肇事事件具有明显的空间分异性,最严重的是包座乡。包座乡临近山区,该区域牧场面积广阔、牧民饲养牲畜数量多等原因导致该镇发生狼肇事事件较多;(3)对于狼肇事,绝大多数牧民(85.0%)更希望采取经济补偿或者驱赶措施,只有少数牧民(9.4%)希望采取捕杀的措施;(4)影响牧民对狼肇事管理措施的偏好因子中,受教育程度、年龄、民族以及被杀牲畜数量有显著影响。建议加强狼种群监测管理,采取措施减少狼捕杀牲畜,优化补偿机制,缓解当地牧民与狼之间的矛盾。本研究为当前若尔盖县野生动物保护和管理决策提供了依据,对其他地区大型食肉动物与当地居民冲突管理具有借鉴意义。 相似文献
5.
6.
V I Rodina N A Krupina G N Kryzhanovski? N B Oknina 《Biulleten' eksperimental'no? biologii i meditsiny》1992,114(7):11-14
A new multiparameter method for evaluating anxiety-phobic states in rats is elaborated. The method is based on the ranged scale consisting of parameters which characterize the species-specific rat response to the series of ethologically adequate test-stimuli inducing manifestation of the anxiety-phobic states. The method makes it possible to evaluate individual anxiety-phobic level in rats, to form experimental groups with rats of known individual anxiety-phobic level, to conduct repeated observations in the same animals. The method is easy to perform in laboratory and makes it possible to get the results quickly. 相似文献
7.
V S Zueva O A Dmitrenko E A Krupina N G Belikov L N Nesterenko 《Zhurnal mikrobiologii, epidemiologii, i immunobiologii》1990,(10):11-15
The resistance of methicillin-resistant staphylococci to phage 85 is due to the presence of a certain system restriction modification in microbial cells. The loss of the capacity for restricting phage DNA by the cell as the consequence of the loss of the mec determinant is not accompanied by the loss of its capacity for modifying phage DNA. 相似文献
8.
Different values have resulted in conflicts between anglers and conservation lobbies in the management of trout in South Africa. Key to the conflict is the demarcation of boundaries to areas in which brown trout Salmo trutta and rainbow trout Oncorhynchus mykiss currently occur, or are likely to establish following stocking for angling. To provide a longer-term perspective on these areas, we developed models to link salmonid biological thermal thresholds to elevation. These, when applied spatially using a digital elevation model with a probability of occurrence model, provided the basis for estimating potentially available thermal habitat for these two cold water species. Here, we acknowledge that other variables (stocking history; river connectivity) also play a role in understanding trout distributions. Using a simple scenario of an increase in mean daily water temperatures of 2 °C, we demonstrated that both brown and rainbow trout are likely to exhibit considerable range reductions in the future. Because it is possible that these range restrictions will result in an increasing desire to introduce trout into areas above their current distribution limits for the maintenance of angling opportunities, conservation managers should prioritise these areas, with management interventions seeking to understand what will help to limit introductions. 相似文献
9.
10.
从茎花葱臭木种子中分离得到5个化合物,经理化与波谱分析鉴定为β-谷甾醇(1)、没食子酸乙酯(2)、胡萝卜苷(3)、1-O-β-D-吡喃葡萄糖基-(2S,3S,4R,8Z)-2-N-(2 ′-羟基二十四烷酰氨基)十八二氧鞘氨-8-烯(4)和2,3,2″,3″-四氢穗花杉双黄酮(5).这5个化合物均首次从该植物中分离得到.其中化合物5进行细胞毒活性测试,没有显示抑制活性. 相似文献