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101.
Yumi Kono Suyun Yang Eve A. Roberts 《In vitro cellular & developmental biology. Animal》1997,33(6):467-472
Summary To develop a strategy for extended primary culture of human hepatocytes, we placed human hepatocytes between two layers of
collagen gel, called a “collagen gel sandwich.” Maintenance of hepatocellular functions in this system was compared with that
of identical hepatocyte preparations cultured on dry-collagen coated dishes or co-cultured with rat liver epithelial cells.
Human hepatocytes in a collagen gel sandwich (five separate cultures) survived for more than 4 wk, with the longest period
of culture being 78 d. They maintained polygonal morphology with bile canaliculuslike structures and high levels of albumin
secretion throughout the period of culture. In contrast, hepatocytes on dry-collagen became feature-less, and albumin secretion
could not be detected after 14 d of culture. This loss of albumin secretion was partially recovered by overlaying one layer
of collagen gel. Ethoxyresorufin O-deethylase activity, associated with cytochrome P450 1A2, was detected basally up to 29 d in collagen gel sandwich culture.
These activities were induced four- to eightfold after induction with dibenz(a,h)anthracene. Cocultures also maintained basal activity up to 29 d. However, their inducibility was lower than that of hepatocytes
in collagen gel sandwich. No ethoxyresorufin O-deethylase activity was detected in hepatocytes cultured on dry-collagen at 7 d. Thus, the collagen gel sandwich system preserves
differentiated morphology and functions of human hepatocytes in primary culture for a prolonged period of time. This system
is a promising model for studying human hepatocellular function, including protein synthesis and drug metabolism in vitro. 相似文献
102.
Chan Alvin C. Wagner Michelle Kennedy Chris Chen Eve Lanuville Odette Mezl Vasek A. Tran Khai Choy Patrick C. 《Molecular and cellular biochemistry》1998,185(1-2):153-159
The alteration in calcium transport in the liver nuclei of rats orally administered carbon tetrachloride (CCl4) was investigated. Rats received a single oral administration of CCl4(5, 10, and 25%, 1.0ml/100 g body weight), and 5, 24 and 48 h later the animals were sacrificed. The administration of CCl4 (25%) caused a remarkable elevetion of calcium content in the liver tissues and the nuclei of rats. Liver nuclear Ca2+-ATPase activity was markedly decreased by CCl4 (25%) administration. The presence of dibutyryl cyclic AMP(10-4 and 10-3 M) or inositol 1,4,5-trisphosphate (10-6 and 10-5 M) in the enzyme reaction mixture caused a significant decrease in Ca2+-ATPase activity in the liver nuclei obtained from normal rat, while the enzyme activity was significantly increased by calmodulin (1.0 and 2.0 g/ml). These signaling factor's effects were completely impaired in the liver nuclei obtained from CCl4 (25%)-administered rats. DNA fragmentation in the liver nuclei obtained from CCl4 -administered rats was significantly decreased by the presence of EGTA (2 mM) in the reaction mixture, suggesting that the endogenous calcium activates nuclear DNA fragmentation. The present study demonstrates that calcium transport system in the liver nuclei is impaired by liver injury with CCl4 administration in rats. 相似文献
103.
SUBPLASMALEMMAL MICROFILAMENTS AND MICROTUBULES IN RESTING AND PHAGOCYTIZING CULTIVATED MACROPHAGES 总被引:53,自引:34,他引:19 下载免费PDF全文
The subplasmalemmal organization of the free and glass-attached surfaces of resting and phagocytizing cultivated macrophages were examined in an attempt to define specific membrane-associated structures related to phagocytosis. From analysis of serial thin sections of oriented cells it was found that the subplasmalemmal region of the attached cell surface has a complex microfilament and microtubule organization relative to the subplasmalemmal area of the free surface. A filamentous network composed of 40–50-Å microfilaments extended for a depth of 400–600 Å from the attached plasma membrane. Immediately subjacent to the filamentous network was a zone of oriented bundles of 40–50-Å microfilaments and a zone of microtubules. Additional microtubules were found to extend from the plasma membrane to the interior of the cell in close association with electron-dense, channellike structures. In contrast, the free aspect of the cultivated macrophage contained only the subplasmalemmal filamentous network. However, after a phagocytic pulse with polystyrene particles (14 µm diam) microtubules and oriented filaments similar to those found on the attached surface were observed surrounding the ingested particles. The observations reported in this paper provide support for the hypothesis that microfilaments and/or microtubules play a role in the translocation of plasma membrane required for the functionally similar processes of phagocytosis and cell attachment to glass. 相似文献
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108.
Salman Azhar Ya Luo Satyanarayana Medicherla Eve Reaven 《Journal of cellular physiology》1999,180(2):190-202
This study examines the effect of mutation of the low-density lipoprotein receptor (LDLR) on cholesterol metabolism, and especially lipoprotein-derived cholesteryl ester uptake, in murine ovarian granulosa cells. Although the tests were conducted on cells prepared by two different procedures, the results are similar. Deletion of LDLR function did not noticeably affect key enzymes of the steroidogenic pathway or affect progestin production and secretion in granulosa cells. No change was found in expression of LDL-related protein (LRP). These data suggested that cholesterol turnover in cells from the knockout animals is within normal limits and that the cells are not stressed to acquire more cholesterol. Both biochemical and morphological data indicate that unstimulated granulosa cells from LDLR−/− mice are nonetheless programmed to take in double the amount of lipoprotein-derived cholesteryl ester (via the selective cholesteryl ester uptake pathway) and to process (hydrolyze, re-esterify, or utilize) more than twofold the cholesteryl ester processed by cells from wildtype (LDLR+/+) animals. Bt2cAMP stimulation of the murine granulosa cells increases the mass of cholesteryl ester taken up by the selective pathway by an additional 38%. To determine to what extent this increase is related to high-density lipoprotein (HDL) scavenger receptor protein (SR-BI) or caveolin function, Western blots and immunohistochemical studies were performed under a variety of conditions. SR-BI levels are found to be low in unstimulated cells of both LDLR+/+ and LDLR−/− animals, but highly expressed (∼20-fold increase over basal levels) in stimulated (Bt2cAMP) cells of both animal models. Thus, the functional relationship between selective cholesteryl ester uptake and SR-BI receptor protein is not as tight as in previously reported studies, suggesting a requirement for other tissue factors. Caveolin expression did not change under any of the conditions tested and appears not to be functionally involved in this process. J. Cell. Physiol. 180:190–202, 1999. Published 1999 Wiley-Liss, Inc. 相似文献
109.
110.
Pogonophora, also known as Siboglinidae, are tube-dwelling marine annelids. They rely on endosymbiotic chemoautotrophic bacteria
for nutrition and their anatomy and physiology are adapted to their need to obtain both oxygen and reduced sulphur compounds.
Frenulate pogonophores are generally long and slender, sediment-living tubeworms; vestimentiferans are stouter, inhabitants
of hydrothermal vents and cool seeps; and moniliferans or sclerolinids are very slender inhabitants of decaying wood and sulphidic
sediments. The anatomy and ultrastructure of the three groups are compared and recent publications are reviewed. Annelid characters
are the presence of chaetae and septa, concentrated at the hind end. The adaptations to a specialised way of life include,
in particular, the chitinous tube; the anterior appendages that function as gills; the internal tissue called the trophosome,
where the endosymbiotic bacteria live; and the blood vascular system that transports oxygen, sulphide and carbon dioxide to
the trophosome. 相似文献