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Between January 1982 and December 1985, 65 species of Mollusca were collected from the Layari River, an ephemeral stream that bisects Karachi. Gastropods were dominant followed by bivalves. The upstream region is hypersaline and devoid of molluscs; the stretch within Karachi is heavily polluted and almost no living molluscs occur here. 相似文献
496.
Background
Poly(ADP-ribose) polymerase is evolutionarily conserved as a responder to various forms of stress. Though PARP's role in cell death is well addressed, its role in development and multicellularity is still an enigma. We have previously reported the role of PARP in oxidative stress induced delayed development of D. discoideum. 相似文献497.
Satoshi Nakaba Shahanara Begum Yusuke Yamagishi Hyun-O Jin Takafumi Kubo Ryo Funada 《Trees - Structure and Function》2012,26(3):743-750
Differences in the timing of cell death, differentiation and function among three different types of ray parenchyma cells
in the hardwood Populus sieboldii × P. grandidentata which form uniseriate and homocellular rays were examined and clarified. Ray parenchyma cells died within 5 years, and the
disappearance of nuclei from ray parenchyma cells did not occur successively from the pith side, even within individual radial
cell lines of a given ray. Cell death occurred earliest in contact cells, which were connected to adjacent vessel elements
through pits, in the fourth annual ring from the cambium. Cell death occurred next in intermediate cells, which were located
within the same cell lines as contact cells but were not adjacent to vessel elements, in the fourth annual ring from the cambium.
Finally, isolation cells, which were located within the other cell lines of a given ray, died in the fifth annual ring from
the cambium. Secondary wall thickenings in contact cells and intermediate cells were initiated before those in isolation cells
in the current year’s xylem. Most starch grains were localized in intermediate cells, and there were more lipid droplets in
contact cells and intermediate cells than in isolation cells. In addition, the largest quantities of protein were found in
contact cells. Our results indicate that the position within a ray and neighboring short-lived vessel elements might affect
the timing of cell death and differentiation and, thus, the function of long-lived ray parenchyma cells in Populus sieboldii × P. grandidentata. 相似文献
498.
Increased plasma glutamic acid in a genetic model of epilepsy 总被引:4,自引:0,他引:4
A significant increase in the plasma levels of glutamic acid and a significant decrease in aspartic acid and taurine in epileptic patients and their first degree relatives was reported more than a decade ago and an underlying genetic basis for these amino acid changes was suggested. The main objective of the present study was to determine the plasma levels of glutamic acid, aspartic acid and taurine in El mice which are an inbred epileptic mutant mouse strain. The results show a significant increase in plasma glutamic acid but no changes in aspartic acid or taurine in the epileptic mice as compared to controls. The data provide the first evidence of a significant increase in plasma glutamic acid in an animal model of hereditary epilepsy and substantiate the hypothesis that a genetic defect underlies the elevated plasma glutamic acid levels in association with epilepsy. The findings are also compatible with neurochemical and neurophysiological evidence implicating glutamic acid in the mechanism of seizures. 相似文献
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Shahanara Begum Satoshi Nakaba Yuichiro Oribe Takafumi Kubo Ryo Funada 《Trees - Structure and Function》2010,24(1):43-52
Differences in the timing of cambial reactivation and the initiation of xylem differentiation in response to the sum of daily
maximum temperatures were studied in two Cryptomeria japonica trees with cambium of different ages under natural and locally heated conditions. In addition, we observed the effects of
low temperature on cambial activity. The timing of cambial reactivation and of the initiation of xylem differentiation differed
between 55- and 80-year-old cambium under natural conditions. In the 55-year-old cambium, cambial reactivation occurred when
the cambial reactivation index (CRI), calculated on the basis of daily maximum temperatures in excess of 10°C, was 94 and
97°C in 2007 and 2008, respectively. In 80-year-old cambium, cambial reactivation occurred when the CRI, calculated on the
basis of daily maximum temperatures in excess of 11°C, was 69 and 71°C in 2007 and 2008, respectively. After cambial reactivation
in 2007, normal cell division was evident in the cambium even though the minimum temperature had fallen between −2 and −3°C.
Under natural conditions, xylem differentiation started 38–44 days after cambial reactivation. In heated stems, the time between
cambial reactivation and the initiation of xylem differentiation ranged from 14 to 16 days, a much shorter time than under
natural conditions, indicating that continuous exposure to an elevated temperature had induced earlier xylem differentiation.
Our observations indicate that the sensitivity to reactivation inducing stimuli of the cambium depends on both the stage of
dormancy and tree age of the cambium. 相似文献