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101.
Haploinsufficiency of cytosolic serine hydroxymethyltransferase in the Smith-Magenis syndrome. 总被引:2,自引:1,他引:1
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S H Elsea R C Juyal S Jiralerspong B M Finucane M Pandolfo F Greenberg A Baldini P Stover P I Patel 《American journal of human genetics》1995,57(6):1342-1350
Folate-dependent one-carbon metabolism is critical for the synthesis of numerous cellular constituents required for cell growth, and serine hydroxymethyltransferase (SHMT) is central to this process. Our studies reveal that the gene for cytosolic SHMT (cSHMT) maps to the critical interval for Smith-Magenis syndrome (SMS) on chromosome 17p11.2. The basic organization of the cSHMT locus on chromosome 17 was determined and was found to be deleted in all 26 SMS patients examined by PCR, FISH, and/or Southern analysis. Furthermore, with respect to haploinsufficiency, cSHMT enzyme activity in patient lymphoblasts was determined to be approximately 50% that of unaffected parent lymphoblasts. Serine, glycine, and folate levels were also assessed in three SMS patients and were found to be within normal ranges. The possible effects of cSHMT hemizygosity on the SMS phenotype are discussed. 相似文献
102.
A rapid method based on previously described DNA extraction procedures was developed for the isolation of DNA from dental plaque samples. The isolated DNA is suitable for use in the PCR. Freeze-thawing, cell wall-degrading enzymes, and guanidine isothiocyanate were used to lyse cells and release DNA. The released DNA was adsorbed onto diatomaceous earth and purified by washing with guanidine isothiocyanate, ethanol, and acetone. The purified DNA was released from the diatomaceous earth into an aqueous buffer and analyzed by PCR with 16S rDNA primers (rDNA is DNA coding for rRNA). As judged from studies with pure cultures of a number of bacterial species, gram-negative and gram-positive organisms were lysed equally well by this procedure. The amount of PCR product was proportional to the number of cells analyzed over the range tested, 500 to 50,000 cells. On the basis of studies with plaque samples that were spiked with known quantities of the oral bacterium Treponema denticola, the DNA prepared from plaque was free of substances inhibitory to PCR. This method should have utility in molecular genetic studies of bacterial populations not only in uncultured plaque samples but also in other complex bacterial assemblages. 相似文献
103.
George A. Carlson Benjamin A. Taylor Susan T. Marshall Arnold H. Greenberg 《Immunogenetics》1984,20(3):287-300
The genetic control of natural resistance in vivo to four natural killer (NK) cell-resistant H-2 homozygous lymphoid tumor cell lines was investigated by following the survival and organ distribution of cells prelabeled with radioactive iododeoxyuridine. Backcross mice derived from DBA/2J and CBA/J parents were injected with H-2
dtumor cells and tumor cell elimination was lowest in H-2
dhomozygotes. Natural killer cell activity was also reduced in mice with the H-2
dhaplotype, but no direct correlation between NK cell levels against YAC-1 or SL2-5 lymphoma cells and natural resistance in vivo was demonstrable. Analysis of 23 BXD recombinant inbred strains indicated that natural resistance to H-2
dtumors was restricted to H-2
bstrains. There was no direct association of NK cell activity with H-2 type in the BXD strains and NK cell levels did not correlate with tumor survival in vivo. By comparing natural resistance to H-2
dand H-2
btumors in DBA/2, C57BL/6, B6D2F1, and B10.D2 mice we found that H-2 nonidentity between the tumor and the host, rather than the host H-2 haplotype, determined whether natural resistance occurred. Again, NK cell activity against YAC-1 cells was not predictive of tumor survival in these strains. These results provide genetic evidence that NK cells alone cannot account for natural resistance to H-2 nonidentical cells of hemopoietic origin. 相似文献
104.
105.
The lowest viscosity that stops translational motility of cells (minimum immobilizing viscosity [MIV] was determined for various spirochetes. The viscous agent used was polyvinylpyrrolidone, The MIV for either Spirochaeta halophila P1 or Spirochaeta aurantia J4T was approximately 1,000 centipoise (cp), and for Leptospira interrogans (biflexa) B16 the MIV was greater than 500 cp. In comparison, the MIV for the flagellated bacteria Escherichia coli and Spirillum serpens was 60 cp. MIV values for two S. halophila mutant strains lacking the characteristic cell coiling (Hel-mutants) were 70 and 120 cp, approximately one-tenth the MIV for the wild-type strain. MIV values for cells of S. aurantia strains with fewer coils than comparably long cells of S. aurantia J4T were 300 to 600 cp. The average velocity of strains of S. aurantia and S. halophila decreased at viscosities higher than 2 to 3 cp. At 2 cp the average velocity of S. halophila P1 was 16 micron/s, whereas the average velocities of Hel-mutant strains were 7 to 9 micron/s. This study indicates that the coiling of spirochetes plays a role in their ability to move through environments of realtively high viscosity. Among the spirochetes we investigated, this ability is greater in the more extensively coiled strains. 相似文献
106.
Using concentrations of [3H] dihydroergokryptine between 0.1 and 5 nM, saturable binding can be demonstrated in rat cerebral cortical membranes with a dissociation constant (KD) of about 0.8 nM. α-Noradrenergic agonists and antagonists compete for the sites labeled by these low concentrations of [3H] dihydroergokryptine with relative potencies characteristics of classical α-noradrenergic receptors. The very low potency of serotonin in competing for these binding sites indicates that, in contrast to findings with higher concentrations of [3H] DHE, low concentrations do not label serotonin receptors. Moreover, the low potency of dopamine in competing for [3H] dihydroergokryptine binding in both striatal and cortical membranes indicates that no detectable portion of binding is associated with postsynaptic dopamine receptors. 相似文献
107.
108.
Composition and molecular organization of lipids and proteins in the envelope of mycoplasmavirus MVL2. 总被引:2,自引:0,他引:2
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MVL2 virus was purified from culture supernatants of infected Acholeplasma laidlawii cells by differential centrifugation, followed by velocity centrifugation in sucrose gradients. The purified virus contained 0.08 to 0.1 mumol of lipid phosphorous per ml of viral protein. Thin-layer chromatography of viral lipids revealed the presence of phospho-, glyco-, and phosphoglycolipids identical with those found in the host cell membrane, but the relative amount of phosphatidylglycerol was much lower than that in the virus. The fatty acid composition of lipids incorporated into the virus included lipids synthesized before and after infection. The freedom of motion of spin-labeled fatty acids in MVL2 depended markedly on temperature and on the position of the nitroxide group on the hydrocarbon chain of the probe, suggesting that the local environment of the probe has the properties of a lipid bilayer. Nevertheless, the lipid hydrocarbon chains in MVL2 appear to be less mobile than those in membranes of the host cells. Polyacrylamide gel electrophoresis of purified MVL2 revealed four major and about five minor polypeptide bands. None of the polypeptide bands gave a positive periodic acid-Schiff reaction. Lactoperoxidase-mediated iodination, followed by proteolytic digestion of intact MVL2 particles, revealed that at least two major polypeptides are localized on the external surface of the viral envelope. 相似文献
109.
110.
S. B. Greenberg G. L. Grove V. J. Cristofalo 《In vitro cellular & developmental biology. Plant》1977,13(5):297-300
Summary Changes in the size of the area covered by individual cultured WI-38 cells as the cultures age have been studied by using
a new microphotographic paper cutout technique. This method is nondestructive and nonintrusive and avoids a number of artifacts
which can occur in the measurement of suspended cells. The measurements reveal that the decreased cell yield of late passage
cultures-reflects not only the appearance of a subpopulation of larger cells but also the failure of the cells to utilize
all the growth surface available to them.
This work was supported in part by USPHS research grant AG-00378 and by a fellowship, AG-05019, from the National Institute
on Aging. 相似文献