全文获取类型
收费全文 | 278篇 |
免费 | 1篇 |
国内免费 | 2篇 |
专业分类
系统科学 | 12篇 |
教育与普及 | 2篇 |
理论与方法论 | 1篇 |
现状及发展 | 58篇 |
研究方法 | 24篇 |
综合类 | 184篇 |
出版年
2022年 | 1篇 |
2021年 | 2篇 |
2019年 | 1篇 |
2018年 | 1篇 |
2014年 | 2篇 |
2013年 | 2篇 |
2012年 | 16篇 |
2011年 | 7篇 |
2010年 | 2篇 |
2008年 | 3篇 |
2007年 | 6篇 |
2006年 | 7篇 |
2005年 | 16篇 |
2004年 | 8篇 |
2003年 | 7篇 |
2002年 | 7篇 |
2001年 | 8篇 |
2000年 | 12篇 |
1999年 | 7篇 |
1992年 | 5篇 |
1991年 | 9篇 |
1990年 | 10篇 |
1989年 | 8篇 |
1988年 | 7篇 |
1987年 | 8篇 |
1986年 | 5篇 |
1985年 | 1篇 |
1984年 | 1篇 |
1983年 | 2篇 |
1982年 | 2篇 |
1981年 | 4篇 |
1980年 | 8篇 |
1979年 | 11篇 |
1978年 | 3篇 |
1977年 | 5篇 |
1976年 | 1篇 |
1975年 | 8篇 |
1974年 | 10篇 |
1973年 | 1篇 |
1972年 | 3篇 |
1971年 | 7篇 |
1970年 | 20篇 |
1969年 | 6篇 |
1968年 | 7篇 |
1967年 | 5篇 |
1966年 | 8篇 |
1965年 | 1篇 |
排序方式: 共有281条查询结果,搜索用时 15 毫秒
101.
Nucleic acid of influenza virus 总被引:6,自引:0,他引:6
102.
Cellular deficit in thymectomized mice 总被引:10,自引:0,他引:10
103.
104.
New cell lines from mouse epiblast share defining features with human embryonic stem cells 总被引:3,自引:0,他引:3
Tesar PJ Chenoweth JG Brook FA Davies TJ Evans EP Mack DL Gardner RL McKay RD 《Nature》2007,448(7150):196-199
105.
Wolkovich EM Cook BI Allen JM Crimmins TM Betancourt JL Travers SE Pau S Regetz J Davies TJ Kraft NJ Ault TR Bolmgren K Mazer SJ McCabe GJ McGill BJ Parmesan C Salamin N Schwartz MD Cleland EE 《Nature》2012,485(7399):494-497
Warming experiments are increasingly relied on to estimate plant responses to global climate change. For experiments to provide meaningful predictions of future responses, they should reflect the empirical record of responses to temperature variability and recent warming, including advances in the timing of flowering and leafing. We compared phenology (the timing of recurring life history events) in observational studies and warming experiments spanning four continents and 1,634 plant species using a common measure of temperature sensitivity (change in days per degree Celsius). We show that warming experiments underpredict advances in the timing of flowering and leafing by 8.5-fold and 4.0-fold, respectively, compared with long-term observations. For species that were common to both study types, the experimental results did not match the observational data in sign or magnitude. The observational data also showed that species that flower earliest in the spring have the highest temperature sensitivities, but this trend was not reflected in the experimental data. These significant mismatches seem to be unrelated to the study length or to the degree of manipulated warming in experiments. The discrepancy between experiments and observations, however, could arise from complex interactions among multiple drivers in the observational data, or it could arise from remediable artefacts in the experiments that result in lower irradiance and drier soils, thus dampening the phenological responses to manipulated warming. Our results introduce uncertainty into ecosystem models that are informed solely by experiments and suggest that responses to climate change that are predicted using such models should be re-evaluated. 相似文献
106.
Intrinsic differences in the growth rate of early nerve fibres related to target distance 总被引:3,自引:0,他引:3
A M Davies 《Nature》1989,337(6207):553-555
Target field innervation in the developing vertebrate nervous system coincides with the onset of important trophic interactions. Two factors that determine the timing of this event are the distance axons have to grow to reach their targets, which are known to vary, and the rate at which they grow. There have been few studies of axonal growth rate at this stage of development and no comparative study of the relationship between growth rate and target distance. Embryonic chick cranial sensory neurons are located in discrete ganglia and the distance axons have to grow to reach their targets is different for each ganglion, ranging from several hundred to several thousand microns. Here, I show that these neurons differ in their in vivo growth rates; neurons with more distant targets growing faster. In vitro, single isolated neurons from each of these populations grow at a similar rate to that observed in vivo, indicating that growth rate is an intrinsically determined property of neurons before they reach their targets. 相似文献
107.
A. H. Davies T. M. Preston C. A. King 《Cellular and molecular life sciences : CMLS》1981,37(7):708-709
Summary The speed of amoeboid locomotion was the same for amoebae moving on the top surface and bottom surface of a horizontal perfusion chamber i.e. cell-substrate adhesive forces must be considerably greater than the gravitational force acting on the locomoting amoeba.Acknowledgments. We would like to thank Les Cooper for technical assistance, and the Science Research Council for support. 相似文献
108.
Human genetics. The essence of inactivity 总被引:4,自引:0,他引:4
109.
Induction of immunological tolerance by porcine liver allografts 总被引:31,自引:0,他引:31
R Y Calne R A Sells J R Pena D R Davis P R Millard B M Herbertson R M Binns D A Davies 《Nature》1969,223(5205):472-476
110.
S N Bose R J Davies D W Anderson J C Van Niekerk L R Nassimbeni R D Macfarlane 《Nature》1978,271(5647):783-784