全文获取类型
收费全文 | 27540篇 |
免费 | 1168篇 |
国内免费 | 8篇 |
出版年
2017年 | 180篇 |
2016年 | 243篇 |
2015年 | 433篇 |
2014年 | 494篇 |
2013年 | 1176篇 |
2012年 | 780篇 |
2011年 | 814篇 |
2010年 | 617篇 |
2009年 | 752篇 |
2008年 | 763篇 |
2007年 | 853篇 |
2006年 | 778篇 |
2005年 | 774篇 |
2004年 | 706篇 |
2003年 | 699篇 |
2002年 | 749篇 |
2001年 | 248篇 |
2000年 | 264篇 |
1999年 | 299篇 |
1998年 | 321篇 |
1997年 | 265篇 |
1996年 | 297篇 |
1995年 | 295篇 |
1994年 | 254篇 |
1993年 | 396篇 |
1992年 | 399篇 |
1991年 | 367篇 |
1990年 | 401篇 |
1989年 | 512篇 |
1988年 | 452篇 |
1987年 | 559篇 |
1986年 | 474篇 |
1985年 | 510篇 |
1984年 | 439篇 |
1983年 | 346篇 |
1982年 | 416篇 |
1981年 | 420篇 |
1980年 | 404篇 |
1979年 | 399篇 |
1978年 | 439篇 |
1977年 | 491篇 |
1976年 | 503篇 |
1975年 | 512篇 |
1974年 | 375篇 |
1973年 | 245篇 |
1972年 | 219篇 |
1971年 | 212篇 |
1970年 | 204篇 |
1969年 | 173篇 |
1964年 | 173篇 |
排序方式: 共有10000条查询结果,搜索用时 140 毫秒
131.
132.
Dr. Ed. Formánek 《Plant Systematics and Evolution》1884,34(5):157-168
Ohne Zusammenfassung 相似文献
133.
134.
Susan F. Hirsch 《American anthropologist》2000,102(1):169-170
Just Words: Law, Language, and Power. John M. Conley and William M. O'Barr. Chicago: The University of Chicago Press, 1998. 168 pp. 相似文献
135.
136.
Claude E. Payri Stéphane Maritorena Christophe Bizeau Michel Rodière 《Journal of phycology》2001,37(2):223-234
Pigment concentration, in vivo absorption, and photosynthetic parameters of the coralline alga Hydrolithon onkodes (Heydrich) Penrose and Woelkerling were compared among samples from a lagoon and from a reef crest of Tahiti Island. Four groups of specimens were considered, differing in their natural exposure to PAR. For specimens collected from the lagoon, the tissues from low-light samples had significantly higher pigment concentration, particularly chl a and phycobilins, compared with the high-light exposed plants that contained more total carotenoids. The in vivo absorption spectra normalized to chl a (called a* values) also revealed differences. The low-light samples had a reduced absorption capacity and a well-marked phycobilin absorption signature, whereas sunlit samples showed a greater absorption at wavelengths absorbed mainly by chl a and carotenoids. The decrease of a* when pigment concentration increased is interpreted as a consequence of the pigment packaging. Significantly lower α (chlorophyll basis) and higher Ek values were found in the shaded plants. The values of P max for the four groups of specimens were not significantly different. The samples showed various degrees of photoinhibition depending on the light exposure during growth, and this effect was more pronounced in the shaded plants. The specimens from the reef crest deviate from the general model presented for the lagoon samples and show a mix of sun- and shade-exposed characteristics. We have shown that the coralline alga H. onkodes responds to its light environment, probably by acclimation rather than ecotypic genetic variation, by adjusting its physiology, but some morphological differences are also involved. Photoacclimation can explain partly the wide distribution of this species over the reef ecosystem and its major contribution to the building of the reef. 相似文献
137.
138.
139.
140.