全文获取类型
收费全文 | 78篇 |
免费 | 2篇 |
出版年
2016年 | 1篇 |
2015年 | 3篇 |
2014年 | 1篇 |
2013年 | 5篇 |
2010年 | 6篇 |
2009年 | 3篇 |
2008年 | 1篇 |
2007年 | 5篇 |
2006年 | 3篇 |
2005年 | 1篇 |
2004年 | 3篇 |
2002年 | 2篇 |
2001年 | 1篇 |
1999年 | 3篇 |
1998年 | 4篇 |
1997年 | 2篇 |
1996年 | 5篇 |
1995年 | 1篇 |
1994年 | 4篇 |
1992年 | 2篇 |
1991年 | 2篇 |
1990年 | 3篇 |
1987年 | 4篇 |
1985年 | 1篇 |
1983年 | 1篇 |
1981年 | 3篇 |
1979年 | 1篇 |
1977年 | 2篇 |
1975年 | 1篇 |
1972年 | 1篇 |
1970年 | 1篇 |
1959年 | 1篇 |
1956年 | 2篇 |
1953年 | 1篇 |
排序方式: 共有80条查询结果,搜索用时 187 毫秒
41.
42.
HIROYUKI SHIMONO MASUMI OKADA MEGURU INOUE HIROFUMI NAKAMURA KAZUHIKO KOBAYASHI TOSHIHIRO HASEGAWA 《Plant, cell & environment》2010,33(3):322-331
Understanding of leaf stomatal responses to the atmospheric CO2 concentration, [CO2], is essential for accurate prediction of plant water use under future climates. However, limited information is available for the diurnal and seasonal changes in stomatal conductance (gs) under elevated [CO2]. We examined the factors responsible for variations in gs under elevated [CO2] with three rice cultivars grown in an open‐field environment under flooded conditions during two growing seasons (a total of 2140 individual measurements). Conductance of all cultivars was generally higher in the morning and around noon than in the afternoon, and elevated [CO2] decreased gs by up to 64% over the 2 years (significantly on 26 out of 38 measurement days), with a mean gs decrease of 23%. We plotted the gs variations against three parameters from the Ball‐Berry model and two revised versions of the model, and all parameters explained the gs variations well at each [CO2] in the morning and around noon (R2 > 0.68), but could not explain these variations in the afternoon (R2 < 0.33). The present results provide an important basis for modelling future water use in rice production. 相似文献
43.
Sympatric speciation has been contentious since its inception, yet is increasingly recognized as important based on accumulating theoretical and empirical support. Here, we present a compelling case of sympatric speciation in a taxon of marine reef fishes using a comparative and mechanistic approach. Hexagrammos otakii and H. agrammus occur in sympatry throughout their ranges. Molecular sequence data from six loci, with complete sampling of the genus, support monophyly of these sister species. Although hybridization occurrs frequently with an allopatric congener in an area of slight distributional overlap, we found no F1 hybrids between the focal sympatric taxa throughout their coextensive ranges. We present genetic evidence for complete reproductive isolation based on SNP analysis of 382 individuals indicating fixed polymorphisms, with no shared haplotypes or genotypes, between sympatric species. To address questions of speciation, we take a mechanistic approach and directly compare aspects of reproductive isolation between allopatric and sympatric taxa both in nature and in the laboratory. We conclude that the buildup of reproductive isolation is strikingly different in sympatric vs. allopatric taxa, consistent with theoretical predictions. Lab reared hybrids from allopatric species crosses exhibit severe fitness effects in the F1 or backcross generation. No intrinsic fitness effects are observed in F1 hybrids from sympatric species pairs, however these treatments exhibited reduced fertilization success and complete pre‐mating isolation is implied in nature because F1 hybrid adults do not occur. Our study addresses limitations of previous studies and supports new criteria for inferring sympatric speciation. 相似文献
44.
MITSUNORI IWATAKI GERT HANSEN ØJVIND MOESTRUP KAZUMI MATSUOKA 《The Journal of eukaryotic microbiology》2010,57(4):308-321
ABSTRACT. The external and internal ultrastructure of the harmful unarmored dinoflagellate Cochlodinium polykrikoides Margalef has been examined with special reference to the apical groove and three‐dimensional structure of the flagellar apparatus. The apical groove is U‐shaped and connected to the anterior sulcal extension on the dorsal side of the epicone. The eyespot is located dorsally and composed of two layers of globules situated within the chloroplast. A narrow invagination of the plasma membrane is associated with the eyespot. The nuclear envelope has normal nuclear pores similar to other eukaryotes but different from the Gymnodinium group with diagnostic nuclear chambers. The longitudinal and transverse basal bodies are separated by approximately 0.5–1.0 μm and interconnected directly by a striated basal body connective and indirectly by microtubular and fibrous structures. Characteristic features of the flagellar apparatus are as follows: (1) a nuclear extension projects to the R1 (longitudinal microtubular root) and is connected to the root by thin fibrous material; (2) fibrillar structures are associated with the longitudinal and transverse flagellar canal; and (3) a striated ventral connective extends toward the posterior end of the cell along the longitudinal flagellar canal. We conclude, based on both morphological and molecular evidence, that Cochlodinium is only distantly related to Gymnodinium. 相似文献
45.
Group spawning (1 female and more than 2 males) and streaking behaviour of subordinate males are common in pelagic‐spawning reef fishes such as the temperate tetrarogidid fish Hypodytes rubripinnis. Five microsatellite loci were isolated and characterized for paternity analysis of this species. Four of the five loci were highly polymorphic, having 11–34 alleles with observed heterozygosities between 0.89 and 1.00 in 37 unrelated individuals. These four loci conformed to Hardy–Weinberg equilibrium. These loci should be useful in future studies that assess how fertilization is partitioned among male H. rubripinnis in multimale spawning events. 相似文献
46.
The impact of exotic trout on native charr in a Japanese stream 总被引:5,自引:1,他引:4
47.
TATSUOMI MATSUOKA RYUSUKE MAMIYA KOJI TANEDA 《The Journal of eukaryotic microbiology》1990,37(4):323-328
Temperature sensitivity of Blepharisma cultured at 23°C was investigated in a temperature range between 18.5°C and 33.5°C. The cells accumulated in an optimal temperature (ca. 27°C) region when they were placed in a chamber with a temperature gradient, although a certain population of the cells accumulated at much higher temperatures. The quantitative analysis of behavioral responses exhibited by the cells revealed that three types of thermal response were responsible for thermoaccumulation of the cells in an optimal temperature: (1) an increase in the frequency of thermophobic response in the cells swimming away from the optimal temperature region; (2) acceleration of forward swimming velocity of the cells swimming toward the optimal temperature region; and (3) higher frequency of spontaneous ciliary reversal of the cells in higher temperature regions. 相似文献
48.
Mikako SAITO Asako KANEDA Tae SUGIYAMA Ryousuke IIDA Keiko OTOKUNI Misako KABURAGI Hideaki MATSUOKA 《Experimental Animals》2015,64(3):231-239
Exon II of glucokinase (Gk) was deleted to produce a systemic
heterozygous Gk knockout (Gk+/−) mouse. The
relative expression levels of Gk in the heart, lung, liver, stomach, and
pancreas in Gk+/− mice ranged from 0.41–0.68 versus that in
wild (Gk+/+) mice. On the other hand, its expression levels in
the brain, adipose tissue, and muscle ranged from 0.95–1.03, and its expression levels in
the spleen and kidney were nearly zero. Gk knockout caused no remarkable
off-target effect on the expression of 7 diabetes causing genes (Shp,
Hnf1a, Hnf1b, Irs1,
Irs2, Kir6.2, and Pdx1) in 10 organs.
The glucose tolerance test was conducted to determine the blood glucose concentrations
just after fasting for 24 h (FBG) and at 2 h after high-glucose application (GTT2h). The
FBG-GTT2h plots obtained with the wild strain fed the control diet (CD),
Gk+/− strain fed the CD, and
Gk+/− strain fed the HFD were distributed in separate areas
in the FBG-GTT2h diagram. The respective areas could be defined as the normal state,
prediabetes state, and diabetes state, respectively. Based on the results, the criteria
for prediabetes could be defined for the Gk+/− strain
developed in this study. 相似文献
49.
SHIGERU KIKUKAWA AKANE HIGUCHI TATSUYA IKEDA TAKESHI MUKAI HIROYUKI OKAMOTO KOUJI TANAKA SYUHEI YAGUCHI 《Physiological Entomology》2009,34(4):333-337
Plodia interpunctella Hübner (Lepidoptera: Pyralidae) comprises a model insect to analyse the photoperiodic time‐measuring system controlling its larval diapause. In the present study, the effective length of light pulse in night interruption experiments is determined at 25 °C. Various lengths of light pulse are tested by inserting them at the midnight of an LD 12 : 12 h photoperiod. When the light pulse is 15 or 30 min, the incidence of diapause is 86%. To inhibit the induction of diapause effectively, a light pulse of 1.75–2 h is needed. The incidence of diapause is 12% under an LD 12 : 5 : 2 : 5 h photoperiod. To determine the precise role of the light pulse, 2‐h light pulses placed at the midnight of an LD 12 : 12 h photoperiod are disrupted systematically by darkness. When a 2‐h light pulse is disrupted by 15 min of darkness, diapause is generally prevented (< 29%) regardless of the temporal position of darkness. Longer disruption by darkness induces diapause moderately (37–67%). A Bünsow experiment is also conducted at 25 and 20 °C, in which the main photophase of 12 h of light is combined with 24–72‐h scotophases scanned by a 2‐h light pulse. The photoperiodic cycle length tested, therefore, varies in the range 36–84 h. In each cycle length, the incidence of diapause fluctuates as the light pulse moves toward dawn. However, no regular and circadian changes in the percentage diapause are observed in relation to diapause determination. 相似文献
50.
NOBUHISA KOGA HIROYUKI TAKAHASHI† KAZUYUKI OKAZAKI† TSUTOMU KAJIYAMA‡ SOHEI KOBAYASHI§ 《Global Change Biology Bioenergy》2009,1(3):220-229
Sugar beet (Beta vulgaris L. subsp. vulgaris) is deemed to be one of the most promising bioethanol feedstock crops in northern Japan. To establish viable sugar beet‐based bioethanol production systems, energy‐efficient protocols in sugar beet cultivation are being intensively sought. On this basis, the effects of alternative agronomic practices for sugar beet production on total energy inputs (from fuels and agricultural materials during cultivation and transportation) and ethanol yields (estimated from sugar yields) were assessed in terms of (i) direct drilling, (ii) reduced tillage (no moldboard plowing), (iii) no‐fungicide application, (iv) using a high‐yielding beet genotype, (v) delayed harvesting and (vi) root+crown harvesting. Compared with the conventional sugar beet production system used in the Tokachi region of Hokkaido, northern Japan, which makes use of transplants, direct drilling and no‐fungicide application contributed to reduced energy inputs from raising seedlings and fungicides, respectively, but sugar (or ethanol) yields were also reduced by these practices, to a greater equivalent extent than the reductions in energy inputs. Consequently, direct drilling (6.84 MJ L?1) and no‐fungicide application (7.78 MJ L?1) worsened the energy efficiency (total energy inputs to produce 1 L of ethanol), compared with conventional sugar beet production practices (5.82 MJ L?1). Sugar yields under conventional plow‐based tillage and reduced tillage practices were similar, but total energy inputs were reduced as a result of reduced fuel consumption from not plowing. Hence, reduced tillage showed improved energy efficiency (5.36 MJ L?1). The energy efficiency was also improved by using a high‐yielding genotype (5.23 MJ L?1) and root+crown harvesting (5.21 MJ L?1). For these practices, no major changes in total energy inputs were noted, but sugar yields were consistently increased. Neither total energy inputs nor ethanol yields were affected by extending the vegetative growing period by delaying harvesting. 相似文献