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71.
Donald L. Hoffman Dr. John H. Abel Jr. Thomas H. McNeill 《Cell and tissue research》1977,182(2):177-191
Summary The role of the paraventricular nucleus (PVN) and biogenic amines (BA) in regulating the level of corticoids in the serum of osmotically stressed mallard ducks (Anas platyrhynchos) was analyzed employing three experimental approaches: 1) pharmacologic alteration of central BA levels, 2) microscopic evaluation of BA distribution, and 3) placement of electrolytic lesions into the PVN. Reserpine and -methyl-p-tyrosine (mpt), agents that decrease the amount of BA's in the central nervous system, produced a fivefold increase in the concentration of serum corticoids. Conversely, pargyline and amphetamine, agents that increase the functional pool of BA's, prevented the rise in serum corticoid concentration normally observed in birds challenged with an intraperitoneal injection of hypertonic saline. When the topographic distribution of BA's was analyzed in the brains of osmotically stressed and nonstressed ducks distinct changes in the intensity of catecholamine (CA) fluorescence were observed in only one location, the PVN of the hypothalamus. Additionally, electrolytic lesions stereotaxically placed in the PVN blocked the osmotic stress-induced rise in serum corticoid concentration. These data therefore indicate that the PVN in the mallard duck plays some role in regulating the observed stress-induced rise in serum corticoid concentration, and that this regulatory function is probably inhibited by catecholamines.This research was supported by research grant No. GB 33321 from the National Science Foundation. We wish to express our sincere thanks to Mr. Howard Funk, research director, Colorado Division of Wildlife, for the use of the State's animal facilitiesThis research was submitted as partial fulfillment for the degree of Doctor of Philosophy, Department of Physiology and Biophysics, Colorado State University, Ft. Collins, CO 80521 相似文献
72.
Harvey R. Herschman Dennis S. Passovoy Rebecca M. Pruss Aharon Aharonov 《Journal of cellular biochemistry》1978,8(3):263-268
The growth-promoting activities of fetal bovine serum, cortisol, phorbol myristate acetate, prostaglandin F2α, insulin, epidermal growth factor, and fibroblast growth factor were evaluated on four murine embryo cell lines (Swiss 3T3, Balb 3T3, M2, and C3H10T1/2). Each cell had an unique response spectrum to this collection of reported mitogens. Phorbol myristate acetate and prostaglandin F2α were active only on selected cell lines; cortisol was inactive on all four lines. Serum, epidermal growth factor, and fibroblast growth factor were able to stimulate cell division in all four lines, albeit to varying degrees for the different target cells. 相似文献
73.
Differences in growth response to hydrocortisone and ascorbic acid by human diploid fibroblasts 总被引:2,自引:0,他引:2
David W. Rowe Barbra J. Starman Wilfred Y. Fujimoto Robert H. Williams 《In vitro cellular & developmental biology. Plant》1977,13(12):824-830
Summary The effects of hydrocortisone and ascorbic acid on growth parameters were measured in human diploid skin fibroblasts from
fetal and adult donors. In the presence of culture medium containing 10% fetal bovine serum, 0.3 μM hydrocortisone produced
a 20% increase in the population growth rate and a 50 to 70% increase in the confluent density of fibroblasts from adult donors.
Daily addition of 28 μM ascorbic acid also stimulated the population growth rate and cell density at confluency. The effects
of hydrocortisone and ascorbic acid on the final cell density were additive. The action of hydrocortisone was restricted to
cells in log-phase growth, whereas ascorbic acid affected cells in both the log and the postconfluent phases of the growth
cycle. In fibroblasts from fetal donors, ascorbic acid was stimulative but hydrocortisone was not. The data suggest that whereas
both compounds stimulate cell growth in an additive manner, they do so by different cellular mechanisms.
This investigation was supported in part by USPHS Grants AM 02456, AM 05020 and AM 15312, and by the Kroc Foundation, No.
UW 63-2986. Dr. Rowe is a fellow of the Helen Hay Whitney Foundation. Dr. Fujimoto is a recipient of a Research Career Development
Award, AM 47142, from NIAMDD. 相似文献
74.
Hugh B. Martin L.L. Houston 《Biochimica et Biophysica Acta (BBA)/Molecular Cell Research》1983,762(1):128-134
A conjugate containing α2-macroglobulin and highly purified ricin A chain was made using N-succinimidyl-3-(2-pyridyldithio)propionate. Radioimmunoassay indicated that it contained 1.2 mol A chain per mol α2-macroglobulin. The conjugate inhibited polyuridylic-acid directed translation by rat liver ribosomes and protein synthesis in human fibroblasts. There was a 90 min lag period before the beginning of inhibition in fibroblasts, but complete inhibition could be achieved. By measuring protein synthesis as a function of protein concentration, it was demonstrated that 8.25·10?9M conjugate was required to inhibit 50% of protein synthesis in 6 h. To achieve the same level of inhibition, 165-times more (1.3·10?6M) unconjugated A chain was required, and 180-times less ricin (4.6·10?11M). Ricin was more than 28 000 times more inhibitory than A chain alone. The presence of α2-macroglobulin did not increase the cytotoxicity of unconjugated A chain, and it even protected the cells to a slight extent. The inhibitory action of the conjugate was blocked by antibodies specific for α2-macroglobulin or ricin, and it was not prevented by galactose or antibodies specific for ricin B chain. Electron microscopy of the conjugate indirectly labelled with ferritin demonstrated that it was internalized by receptor mediated endocytosis through coated pits. These data indicate that the A chain portion of the conjugate survives the conditions in the lysosomes to the extent that it retains its ability to inactivate cytoplasmic ribosomes. 相似文献
75.
Developmental changes in the calcium currents in embryonic chick ventricular myocytes 总被引:1,自引:0,他引:1
Summary Using the patch-clamp technique, we recorded whole-cell calcium current from isolated cardiac myocytes dissociated from the apical ventricles of 7-day and 14-day chick embryos. In 70% of 14-day cells after 24 hr in culture, two component currents could be separated from totalI
Ca activated from a holding potential (V
h) of –80 mV. L-type current (I
L) was activated by depolarizing steps fromV
h –30 or –40 mV. The difference current (I
T) was obtained by subtractingI
L, fromI
Ca.I
T could also be distinguished pharmacologically fromI
L in these cells.I
T was selectively blocked by 40–160 m Ni2+, whereasI
L was suppressed by 1 m D600 or 2 m nifedipine. The Ni2+-resistant and D600-resistant currents had activation thresholds and peak voltages that were near those ofI
T andI
L defined by voltage threshold, and resembled those in adult mammalian heart. In 7-day cells,I
T andI
L could be distinguished by voltage threshold in 45% (S cells), while an additional 45% of 7-day cells were nonseparable (NS) by activation voltage threshold. Nonetheless, in mostNS cells,I
Ca was partly blocked by Ni2+ and by D600 given separately, and the effects were additive when these agents were given together. Differences among the cells in the ability to separateI
T andI
L by voltage threshold resulted largely from differences in the position of the steady-state inactivation and activation curves along the voltage axis. In all cells at both ages in which the steady-state inactivation relation was determined with a double-pulse protocol, the half-inactivation potential (V
1/2) of the Ni2+-resistant currentI
L averaged –18 mV. In contrast,V
1/2 of the Ni2+-sensitiveI
T was –60 mV in 14-day cells, –52 mV in 7-dayS cells, and –43 mV in 7-day NS cells. The half-activation potential was near –2 mV forI
L at both ages, but that ofI
T was –38 mV in 14-day and –29 mV in 7-day cells. Maximal current density was highly variable from cell to cell, but showed no systematic differences between 7-day and 14-day cells. These results indicate that the main developmental change that occurs in the components ofI
Ca is a negative shift with, embryonic age in the activation and inactivation relationships ofI
T along the voltage axis. 相似文献
76.
Summary A serum-free culture system supplemented with neural tissue extract for normal and tumor human esophagi was applied to the
culture of mouse esophageal epithelium. Similar to mouse mesenchyme and skin epithelium, esophageal epithelial lines (MEE)
emerged after serial culture. The cells had an apparent unlimited life span but retained morphology and other characteristics
of normal epithelial cells. The cells formed a small cyst consisting of keratined squamous epithelium in syngenic hosts. A
screen for growth factors that stimulated growth of the nonmalignant MEE cells in the absence of neural extract revealed that
epidermal growth factor (EGF) and heparin-binding (fibroblast) growth factors (HBGF) were most effective. An HBGF-like activity
was apparent in extracts of rapidly proliferating but not quiescent MEE cells at low or confluent densities. A cloned cell
line (MEE/C8) was selected from MEE cell cultures in the absence of neural extract. MEE/C8 cells proliferated independent
of either EGF or HBGF at rates equal to MEE cells, cell extracts exhibited HBGF-like activity at all stages of proliferation,
and the cells formed large invasive tumors in syngenic hosts. The HBGF-like activity present in extracts of tumorigenic MEE/C8
and proliferating nonmalignant MEE cells had properties similar to HBGF-1 (acidic fibroblast growth factor). These results
constitute a cultured mouse esophageal epithelial cell model for study of conversion of immortalized premalignant cells to
malignant cells, and suggest that conversion from a state of cell cycle-dependent autocrine expression of one or more members
of the HBGF family to a state of constitutive expression correlates with and may contribute to malignancy.
The work was supported in part by grants CA37589 and DK35310 to Dr. McKeehan, from the National Cancer Institute, Bethesda,
MD. 相似文献
77.
In an attempt to determine whether phagocytosis of collagen by fibroblasts involves binding of the fibril to the plasma membrane, the effect of the lectin concanavalin A (Con A) was studied in an in vitro model system. Metacarpal bone rudiments from 19-day-old mouse fetuses were incubated with varying concentrations of the lectin. Quantitative electron microscopic analysis indicated that Con A caused a dose-related increase in the amount of phagocytosed collagen fibrils in periosteal fibroblasts, suggesting either an enhanced uptake or a decreased intracellular breakdown of fibrils. Since a Con A-inducible increase was not seen in the combined presence of both the lectin and the proteinase inhibitor leupeptin, which is known to inhibit the intracellular digestion of phagocytosed fibrillar collagen, it is unlikely that Con A stimulated phagocytosis. Based on the finding that Con A interfered with the digestion of a synthetic substrate by the collagenolytic lysosomal enzyme cathepsin B it is suggested that the augmentation of intracellular fibrillar collagen under the influence of the lectin was due to a decreased intracellular digestion. Since Con A did not inhibit the uptake of collagen fibrils by the fibroblasts it is concluded that Con A-inhibitable binding sites for collagen molecules are unlikely to be involved in phagocytosis of collagen fibrils by fibroblasts. 相似文献
78.
Yanan Zhang Dilbir S. Bindra Marie-Bernadette Barrau George S. Wilson 《Biosensors & bioelectronics》1991,6(8):653-661
Cell culture toxicity testing methods were modified and applied to the development of implantable glucose microsensors, and positive and negative control materials suitable for the microsensor assessment were established. The location, source and degree of the toxic effect in a multi-component biosensor was spatially visualized with cell monolayers. A freshly prepared sensor showed moderate toxicity, mainly as a result of the presence of glutaraldehyde and the residual solvents in the polymer layers. However, it was possible to reduce the toxicity by removing the leachable toxic substances through extraction in phosphate, buffer, and a non-toxic sensor was readily obtained. 相似文献
79.
Neuroethological approaches to the study of motor development in chicks: Achievements and challenges
Anne Bekoff 《Developmental neurobiology》1992,23(10):1486-1505
Chicks and chick embryos provide a useful model system for the study of related to the development of motor behaviors. EMG and kinematic analyses of leg movements have been used to provide new data on the organization of embryonic motility. These data suggest that the circuitry needed to produce a basic, coordinated motor pattern is available early in development. This circuitry then appears to be retained throughout life. Evidence from analysis of EMG patterns and leg deafferentation studies suggest that the output of this basic circuit can be modulated by sensory input to produce the motor patterns of later behaviors, such as hatching and walking. If the same circuitry is present throughout life, then mechanisms for initiation and termination of particular behaviors must be available to ensure that specific behaviors are turned on and off at appropriate times. For example, hatching can be turned on by a specific sensory signal: proprioceptive signals from the bent neck. In addition to reviewing current research on the development of chick motor behaviors, methodological considerations and suggestions for future research are presented. © 1992 John Wiley & Sons, Inc. 相似文献
80.
M.J. Edwards W.K. Kaufmann 《Biochimica et Biophysica Acta (BBA)/Molecular Cell Research》1982,721(2):223-225
Replicative DNA synthesis in normal human fibroblasts was inhibited by 50% when they were X-irradiated (8 Gy) and made permeable 30 min later, whereas only a slight inhibition (20%) was observed in similarly treated ataxia-telangiectasia cells. Treatment of irradiated normal cells with caffeine (2 mM) before permeabilization reversed the inhibitory effects of X-rays, buf caffeine had no effect on DNA synthesis in permeable ataxia-telangiectasia cells. Diadenosine tetraphosphate (0.1 mM) did not affect DNA synthesis in permeable normal fibroblasts. 相似文献