全文获取类型
收费全文 | 1145篇 |
免费 | 33篇 |
专业分类
1178篇 |
出版年
2017年 | 12篇 |
2015年 | 18篇 |
2014年 | 20篇 |
2013年 | 29篇 |
2012年 | 21篇 |
2011年 | 24篇 |
2010年 | 37篇 |
2009年 | 27篇 |
2008年 | 33篇 |
2007年 | 57篇 |
2006年 | 29篇 |
2005年 | 24篇 |
2004年 | 24篇 |
2003年 | 18篇 |
2002年 | 22篇 |
2000年 | 12篇 |
1999年 | 16篇 |
1998年 | 12篇 |
1997年 | 19篇 |
1996年 | 14篇 |
1995年 | 16篇 |
1994年 | 17篇 |
1993年 | 21篇 |
1992年 | 12篇 |
1991年 | 19篇 |
1990年 | 22篇 |
1989年 | 14篇 |
1988年 | 13篇 |
1987年 | 22篇 |
1986年 | 17篇 |
1985年 | 14篇 |
1984年 | 13篇 |
1982年 | 13篇 |
1980年 | 13篇 |
1979年 | 12篇 |
1976年 | 12篇 |
1974年 | 18篇 |
1973年 | 18篇 |
1972年 | 21篇 |
1971年 | 15篇 |
1970年 | 11篇 |
1965年 | 36篇 |
1964年 | 19篇 |
1963年 | 32篇 |
1962年 | 23篇 |
1961年 | 35篇 |
1960年 | 21篇 |
1959年 | 27篇 |
1958年 | 28篇 |
1957年 | 12篇 |
排序方式: 共有1178条查询结果,搜索用时 13 毫秒
71.
72.
SYNOPSIS. Supraspecific taxa of the ciliate Order Tintinnida Corliss, 1955 are indexed by 304 entries; genetic type species are cited with reference to the original citation. The accompanying bibliography of 133 entries includes those publications cited in the index. Authors for several type citations are corrected, as is authorship of some genera, and a new type designation is made for Parundella to replace the previous erroneous designation. Genera present in the fossil record are so indicated. 相似文献
73.
74.
ROWLAND-BAMFORD AMANDA J; ALLEN L HARTWELL JR; BAKER JEFFREY T; BOOTE KEN J 《Journal of experimental botany》1990,41(12):1601-1608
The atmospheric carbon dioxide (CO2) concentration has beenrising and is predicted to reach double the present concentrationsometime during the next century. The objective of this investigationwas to determine the long-term effects of different CO2 concentrationson carbohydrate status and partitioning in rice (Oryza sativaL cv. IR-30). Rice plants were grown season-long in outdoor,naturally sunlit, environmentally controlled growth chamberswith CO2 concentrations of 160, 250, 330, 500, 660, and 900µmolCO2 mol1 air. In leaf blades, the priority between the partitioningof carbon into storage carbohydrates or into export changedwith developmental stage and CO2 concentration. During vegetativegrowth, leaf sucrose and starch concentrations increased withincreasing CO2 concentration but tended to level off above 500µmolmol1 CO2. Similarly, photosynthesis also increased withCO2 concentrations up to 500µmol mol1 and thenreached a plateau at higher concentrations. The ratio of starchto sucrose concentration was positively correlated with theCO2 concentration. At maturity, increasing CO2 concentrationresulted in an increase in total non-structural carbohydrate(TNC) concentration in leaf blades, leaf sheaths and culms.Carbohydrates that were stored in vegetative plant parts beforeheading made a smaller contribution to grain dry weight at CO2concentrations below 330µmol mol1 than for treatmentsat concentrations above ambient Increasing CO2 concentrationhad no effect on the carbohydrate concentration in the grainat maturity Key words: CO2 enrichment, starch, sucrose 相似文献
75.
76.
77.
78.
KHALIFAH R. A.; LEWIS L. N.; COGGINS C. W. JR.; RADLICK P. C. 《Journal of experimental botany》1965,16(3):511-517
Evidence for the non-indolic nature of the new citrus auxinis presented on the basis of fluorometric properties, thin-layerchromatography, Ehrlich's colour reaction, paper electrophoresis,and the infra-red spectra determinations. Citrus auxin had alower Rf in TLC than IAA, did not give the typical indole reactionwith Ehrlich's reagent, and behaved differently in electrophoresis.The infra-red spectra also provided preliminary informationconcerning chemical structure. The hypothesis that indolic compoundsconstitute the only natural auxins in higher plants should berevised in view of this evidence that a non-indole auxin existsin higher plants. 相似文献
79.
We describe an illusion in which a stranger's voice, when presented as the auditory concomitant of a participant's own speech, is perceived as a modified version of their own voice. When the congruence between utterance and feedback breaks down, the illusion is also broken. Compared to a baseline condition in which participants heard their own voice as feedback, hearing a stranger's voice induced robust changes in the fundamental frequency (F0) of their production. Moreover, the shift in F0 appears to be feedback dependent, since shift patterns depended reliably on the relationship between the participant's own F0 and the stranger-voice F0. The shift in F0 was evident both when the illusion was present and after it was broken, suggesting that auditory feedback from production may be used separately for self-recognition and for vocal motor control. Our findings indicate that self-recognition of voices, like other body attributes, is malleable and context dependent. 相似文献
80.