全文获取类型
收费全文 | 399篇 |
免费 | 15篇 |
出版年
2022年 | 5篇 |
2021年 | 5篇 |
2020年 | 5篇 |
2019年 | 2篇 |
2018年 | 5篇 |
2017年 | 8篇 |
2016年 | 7篇 |
2015年 | 9篇 |
2014年 | 15篇 |
2013年 | 40篇 |
2012年 | 20篇 |
2011年 | 19篇 |
2010年 | 17篇 |
2009年 | 10篇 |
2008年 | 19篇 |
2007年 | 28篇 |
2006年 | 11篇 |
2005年 | 22篇 |
2004年 | 15篇 |
2003年 | 12篇 |
2002年 | 9篇 |
2001年 | 4篇 |
2000年 | 7篇 |
1999年 | 9篇 |
1998年 | 12篇 |
1997年 | 7篇 |
1996年 | 8篇 |
1995年 | 8篇 |
1994年 | 6篇 |
1993年 | 4篇 |
1992年 | 2篇 |
1991年 | 2篇 |
1990年 | 3篇 |
1989年 | 4篇 |
1988年 | 4篇 |
1987年 | 3篇 |
1986年 | 2篇 |
1985年 | 2篇 |
1984年 | 7篇 |
1983年 | 5篇 |
1982年 | 4篇 |
1981年 | 7篇 |
1980年 | 4篇 |
1979年 | 2篇 |
1977年 | 2篇 |
1973年 | 3篇 |
1968年 | 1篇 |
1964年 | 1篇 |
1960年 | 1篇 |
1923年 | 1篇 |
排序方式: 共有414条查询结果,搜索用时 390 毫秒
71.
The relationship between phylogeny and nucleomorph genome size was examined in 16 strains of cryptomonad algae using pulsed‐field gel electrophoresis, Southern hybridization and phylogenetic analyses. Our results suggest that all cryptomonads examined in this study contain three nucleomorph chromosomes and their total genome size ranges from 495 to 750 kb. In addition, we estimated the plastid genome size of the respective organisms. The plastid genomes of photosynthetic strains were approximately 120–160 kb in size, whereas the non‐photosynthetic Cryptomonas paramecium NIES715 possesses a genome of approximately 70 kb. Phylogenetic analysis of the nuclear small subunit ribosomal DNA (SSU rDNA) gene showed that nucleomorph genome size varies considerably within closely related strains. This result indicates that the reduction of nucleomorph genomes is a rapid phenomenon that occurred multiple times independently during cryptomonad evolution. The nucleomorph genome sizes of Cryptomonas rostratiformis NIES277 appeared to be approximately 495 kb. This is smaller than that of Guillardia theta CCMP327, which until now was thought to have the smallest known nucleomorph genome size among photosynthetic cryptomonads. 相似文献
72.
73.
Primates often modify dietary composition in relation to seasonal changes in food availability or climate conditions. We studied the feeding patterns of a troop of common brown lemurs (Eulemur fulvus), a semi-frugivorous strepsirhine, in a dry forest in northwestern Madagascar. To understand the mechanism of dietary modification, we recorded daily feeding times of diet items during 101 full-day observations over 1 year, and then conducted a linear model analysis to examine the effects of fruiting tree density in the forest, daily ambient temperature, and weekly rainfall (index of water retained in the forest) on the lemurs' daily feeding time. The lemurs spent dramatically more time on leaf-eating as well as total feeding time, and less time on fruit-eating during the late dry season (total 152 min/day, frugivory 56 min/day, folivory 77 min/day), as compared with other seasons when the diet was highly frugivorous (total 96 min/day, frugivory 81 min/day, folivory 8 min/day). Folivory increased as temperatures rose under the condition of low weekly rainfall, whereas frugivory was unrelated to fruiting tree density. Most (97.4 %) diurnal folivory during the late dry season was spent consuming Lissochilus rutenbergianus, chewing the succulent leaves and licking the juice. Because the nutritional analysis showed that L. rutenbergianus is rich in water (80.1 % of fresh weight) but poor in protein and nonstructural carbohydrates, its increased use was probably for rehydration. We conducted 13 full-night observations, because brown lemurs increase nocturnal activities during the dry season. At nighttime, the lemurs tended to spend more time eating fruit in the late dry season (32 min/night) than in the early dry season (14 min/night), and never consumed L. rutenbergianus. Fruits rich in nonstructural carbohydrates can be energy sources for Eulemur. They likely engaged in additional nocturnal frugivory for energy compensation. Brown lemurs have a flexible strategy of modifying their diet and feeding activities to cope with environmental stresses. 相似文献
74.
75.
Hanya G Ménard N Qarro M Ibn Tattou M Fuse M Vallet D Yamada A Go M Takafumi H Tsujino R Agetsuma N Wada K 《Primates; journal of primatology》2011,52(2):187-198
Habitat, diet and leaf chemistry are compared between Japanese and Barbary macaques to reveal the similarities and differences in dietary adaptations of temperate primates living at the eastern and western extremes of the genus Macaca. Tree species diversity and proportion of fleshy-fruited species are much higher in Japan than in North Africa. Both species spend considerable annual feeding time on leaves. Japanese macaques prefer fruits and seeds over leaves, and Barbary macaques prefer seeds. These characteristics are adaptive in temperate regions where fruit availability varies considerably with season, since animals can survive during the lean period by relying on leaf and other vegetative foods. The two species are different with respect to the higher consumption of herbs by Barbary macaques, and the leaves consumed contain high condensed and hydrolysable tannin for Barbary but not for Japanese macaques. Barbary macaques supplement less diverse tree foods with herbs. Because of the low species diversity and high tannin content of the dominant tree species, Barbary macaques may have developed the capacity to cope with tannin. This supports the idea that digestion of leaves is indispensable to survive in temperate regions where fruit and seed foods are not available for a prolonged period during each year. 相似文献
76.
Goro Kokubugata Yumiko Hirayama Ching-I Peng Masatsugu Yokota Michael M?ller 《Plant Systematics and Evolution》2011,292(3-4):177-188
Comparison of leaf morphometric variation and phylogenetic analyses based on nrITS and partial trnC-D cpDNA sequences were conducted for samples of Lysionotus pauciflorus sensu lato collected from China, Japan and Taiwan. In the morphometric comparison, leaves of plants from Japan proper and those from Taiwan proper were not significantly distinguishable by their leaf length to width ratio. In phylogenetic analyses, monophyly of L. pauciflorus s. l. samples was strongly supported, and Japanese and Taiwanese samples fell into a clade separate from Chinese samples. In the Japan?CTaiwan clade, plants from Japan proper formed a sister clade to those from Okinawa Island (Japan) and Taiwan. The present results suggest that (1) the L. pauciflorus s. l. samples from China, Japan and Taiwan must be treated as a single species; (2) L. pauciflorus s. l. originated in China; (3) a single dispersal event, dispersal via a land-bridge during low sea levels in a Pleistocene glacial maximum, from China to Taiwan and Japan is proposed; (4) three oversea dispersal events, probably through anemochory, to Japan proper, across the Tokara Gap, to Okinawa islands crossing the Kerama Gap, and from Taiwan to Lanyu Island are proposed. The study gives further insight into the biogeographical dynamics between the Ryukyus and surrounding areas. 相似文献
77.
Seiji Komeda Tinoush Moulaei Masahiko Chikuma Akira Odani Ralph Kipping Nicholas P. Farrell Loren Dean Williams 《Nucleic acids research》2011,39(1):325-336
The 1.7 Å X-ray crystal structure of the B-DNA dodecamer, [d(CGCGAATTCGCG)]2 (DDD)-bound non-covalently to a platinum(II) complex, [{Pt(NH3)3}2-µ-{trans-Pt(NH3)2(NH2(CH2)6NH2)2}](NO3)6 (1, TriplatinNC-A,) shows the trinuclear cation extended along the phosphate backbone and bridging the minor groove. The square planar tetra-am(m)ine Pt(II) units form bidentate N-O-N complexes with OP atoms, in a Phosphate Clamp motif. The geometry is conserved and the interaction prefers O2P over O1P atoms (frequency of interaction is O2P > O1P, base and sugar oxygens > N). The binding mode is very similar to that reported for the DDD and [{trans-Pt(NH3)2(NH2(CH2)6(NH3+)}2-µ-{trans-Pt(NH3)2(NH2(CH2)6NH2)2}](NO3)8 (3, TriplatinNC), which exhibits in vivo anti-tumour activity. In the present case, only three sets of Phosphate Clamps were found because one of the three Pt(II) coordination spheres was not clearly observed and was characterized as a bare Pt2+ ion. Based on the electron density, the relative occupancy of DDD and the sum of three Pt(II) atoms in the DDD-1 complex was 1:1.69, whereas the ratio for DDD-2 was 1:2.85, almost the mixing ratio in the crystallization drop. The high repetition and geometric regularity of the motif suggests that it can be developed as a modular nucleic acid binding device with general utility. 相似文献
78.
Tamura Y Hirohashi Y Kutomi G Nakanishi K Kamiguchi K Torigoe T Sato N 《Journal of immunology (Baltimore, Md. : 1950)》2011,186(7):4325-4330
Binding of immunoglobulin protein (BiP) is a major molecular chaperone localized in endoplasmic reticulum (ER). It has been demonstrated to interact with nascent Ig. However, contrary to other ER-resident heat shock proteins such as gp96, calreticulin, and ORP150, it is not clear whether tumor-derived BiP plays a role in inducing antitumor immunity. In this study, we show that the tumor-derived secreted form of BiP is capable of inducing antitumor CD8(+) T cell responses. We constructed an ER-retention signal KDEL-deleted mutant of BiP cDNA and transfected it to tumor cells, which resulted in continuous secretion of tumor-derived BiP into the extracellular milieu. We show that this secreted BiP is taken up by bone marrow-derived dendritic cells, and thereafter BiP-associated Ag peptide is cross-presented in association with MHC class I molecules, resulting in elicitation of an Ag-specific CD8(+) T cell response and antitumor effect. This strategy to boost antitumor immune responses shows that a tumor could be its own cellular vaccine via gene modification of the secretion of the tumor Ag-BiP complex. 相似文献
79.
80.
Goro Tanifuji Naoko T Onodera Matthew W Brown Bruce A Curtis Andrew J Roger Gane Ka-Shu Wong Michael Melkonian John M Archibald 《BMC genomics》2014,15(1)