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1.
Calorimetric properties of mixtures of ganglioside GM1 and dipalmitoylphosphatidylcholine 总被引:2,自引:0,他引:2
L O Sillerud D E Schafer R K Yu W H Konigsberg 《The Journal of biological chemistry》1979,254(21):10876-10880
2.
Restriction sites containing CpG show a higher frequency of polymorphism in human DNA 总被引:122,自引:0,他引:122
Unique loci in the human genome were examined with restriction enzymes in order to detect restriction fragment length polymorphisms (RFLPs). Of 31 arbitrary loci, nine were detectably polymorphic, reflecting ten polymorphic restriction sites. Nine of the ten polymorphic sites were revealed with two restriction enzymes, Msp I and Taq I, whose recognition sequences have in common the dimer sequence CpG. The cytosines in the CpG sequence are known to be frequently methylated in mammals, and the occurrence of significant variation in Msp I and Taq I sites supports the view that methylated cytosine residues are hotspots for mutation in mammalian DNA. 相似文献
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R Schafer C A Nacy T K Eisenstein 《Journal of immunology (Baltimore, Md. : 1950)》1988,140(5):1638-1644
A single injection of viable Salmonella typhimurium SL3235, an avirulent organism blocked in the aromatic pathway, induced the generation of activated peritoneal macrophages in three different C3H mouse strains, including macrophage-defective C3H/HeJ mice. Macrophages obtained from immunized mice were cytotoxic for B16 melanoma cells, P815 mastocytoma cells, and TU-5 fibrosarcoma cells and microbicidal in vitro for the obligate, intracellular, protozoan parasite Leishmania major. The capacity of live SL3235 to activate C3H/HeJ macrophages contrasts with the failure of live Bacillus Calmette-Guérin to induce activated macrophages in this mouse strain. Although viable SL3235 were capable of fully activating cells of both normal and defective mice, a dose-dependent difference was observed in the number of organisms necessary for induction of tumoricidal macrophages in C3HeB/FeJ (normal) and C3H/HeJ (defective) animals. As few as 80 viable SL3235 were capable of activating C3HeB/FeJ macrophages whereas 5 X 10(4) organisms were required to activate C3H/HeJ macrophages. Maximal macrophage activation occurred 7 to 10 days after SL3235 inoculation in C3H/HeJ and C3HeB/FeJ mice. Acetone-killed cells of SL3235 had some but not all of the activity of the living Salmonella. A single in vivo injection of the nonviable preparation resulted in the induction of tumoricidal macrophages in C3HeB/FeJ but not in C3H/HeJ mice, even when tested over a wide dosage range. Injection of acetone-killed cells of SL3235 did, however, result in a population of primed macrophages in C3H/HeJ mice, as explanted cells could be induced to express activated macrophage effector activities after additional treatment in vitro with either LPS or IFN-gamma. Thus, in vivo administration of viable SL3235 is, by itself, capable of eliciting the full series of steps required for activation of C3H/HeJ macrophages, whereas killed SL3235 only provides signals sufficient to prime these defective macrophages for further activation in vitro. AI 15613 相似文献
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- 1. The net uptake of α-aminoisobutyric acid (AIB) in Ehrlich ascites tumor cells has been studied under a variety of transmembrane concentration gradients of Na+, K+ and AIB itself. 相似文献
6.
Ting-Yang Lee Irwin A. Schafer 《Biochimica et Biophysica Acta (BBA)/General Subjects》1974,354(2):264-274
The glycosaminoglycan composition of human amniotic fluid between 12–21 weeks gestation has been studied by Dowex column chromatography coupled with enzymatic analyses of the specific glycosaminoglycan in each column fraction. The total uronic acid recovered from the columns consisted of “glycopeptides” (7%), hyaluronic acid (34%), nonsulfated chondroitin (14%), chondroitin-4-sulfate (13%), chondroitin-6-sulfate (20%), dermatan sulfate (5%), and heparan sulfate (6%). Based on these studies a simple screening procedure was devised to detect increased quantities of heparan sulfate and dermatan sulfate in 5–10-ml samples of amniotic fluid and tested in the antenatal diagnosis of Hurler and Hunter's syndrome. A false negative result was recorded in a Hunter fluid obtained early gestation and a false positive result recorded in a normal fluid obtained at
weeks. These data suggest that the time in gestation when amniotic fluid is sampled for chemical analysis is an important variable affecting glycosaminoglycan composition in both normal and pathological pregnancies. 相似文献
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I A Schafer A M Jamieson M Petrelli B J Price G C Salzman 《The journal of histochemistry and cytochemistry》1979,27(1):359-365
Multi-angle light scattering flow photometry was used to study the light scattering properties of normal cultured fibroblasts and a mutant fibroblast line containing cytoplasmic lysosomal inclusions. The effect of glutaraldehyde fixation on the light scattering properties of the cells was also examined and correlated with their ultrastructure. Normal fibroblasts showed uniform organelle distribution with few vacuoles or dense bodies in the cytoplasm while the mutant line showed abnormal cytoplasmic inclusions of varying morphology, density and lucency. As predicted by light scattering theory, the mutant cells containing the cytoplasmic inclusions scattered more light at large angles (greater than theta = 1.85 degrees) than did the normal cells. Glutaraldehyde fixation decreased light scattering at small angles (less than theta = 1.85 degrees), increased light scattering at larger angles (greater than theta = 1.85 degrees) in both normal and mutant cells and enhanced resolution of the light scattering signatures. The mutant line scattered 2-3 times more light at a wide angle (greater than theta = 12.74 degrees) than did the normal cells. These data suggest that abnormal lysosomal storage inclusion bodies in the cytoplasm of the cells can be detected by differential light scattering methods. 相似文献
10.
Irwin A. Schafer Maureen Kovach Robert L. Price Richard B. Fratianne 《Experimental cell research》1991,195(2)
Single cell suspensions of human keratinocytes when seeded onto floating three-dimensional gels constructed with type I collagen form a tissue resembling epidermis. These morphogenetic events occur in a serum-free environment in the absence of fibroblasts. Light and transmission electron microscopy show that cells form a basal layer plus suprabasilar cell layers corresponding to the stratum spinosum, stratum granulosum, and stratum corneum. The suprabasilar keratinocyte layers show morphologies which resemble intact skin in which cells are connected by desmosomes and contain intermediate filaments and keratohyalin-fillagrin granules. The basal cell layer differs from skin in vivo in that there is no connection to a basement membrane via hemidesmosomes. Cells in the basal layers are polarized as evidenced by the secretion of type IV collagen, heparan sulfate proteoglycans, and laminin at the cell membrane interface with the collagen gel. These proteins are not organized into a cytological basement membrane. Bullous pemphigoid antigen, a protein component of hemidesmosomes, is synthesized by basal keratinocytes, but like the basement membrane proteins it is not incorporated into a definable cytological structure. Keratinocytes in the basal and suprabasilar layers also synthesize α2β1 integrins. The mechanisms of keratinocyte adhesion to the gel may be through the interactions of this cell surface receptor with laminin and type IV collagen synthesized by the cell and/or direct interactions between the receptor and type I collagen within the gel. This in vitro experimental system is a useful model for defining the molecular events which control the formation and turnover of basement membranes and the mechanisms by which keratinocytes adhere to type I collagen when sheets of keratinocytes are used clinically for wound coverage. 相似文献