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排序方式: 共有341条查询结果,搜索用时 16 毫秒
41.
Ways DK; Qin W; Riddle RS; Garris TD; Bennett TE; Steelman LS; McCubrey JA 《Blood》1991,78(10):2633-2641
FD/PMA is a subclone of the interleukin-3 (IL-3)-dependent, FDC-P1 cell line, which proliferates in response to either 12-O- tetradecanoylphorbol-13 acetate (PMA) or IL-3. While several endogenous substrates were phosphorylated in response to protein kinase C (PKC) activation in FDC-P1, phospholipid-dependent phosphorylation in the FD/PMA grown in PMA was not observed. Basal, phosphatidylserine- independent, and diolein-independent phosphorylation of cytosolic substrates with molecular weights of 17, 52, 57, and 105 Kd were enhanced in FD/PMA cells grown in PMA as compared with FDC-P1 cells cultured in IL-3. Phosphorylation of a 105-Kd substrate was enhanced in the particulate fraction of FD/PMA cells maintained in PMA. The 17-Kd substrate in FD/PMA cells comigrated with a substrate phosphorylated in a PKC-dependent manner in FDC-P1 cells. Phosphorylation of the 52- and 57-Kd substrates, but not of the 17-Kd substrate, was inhibited by H-7 and staurosporine. A portion of the PMA-induced cytosolic kinase activity coeluted with PKC on diethyl aminoethyl chromatography. While FD/PMA cells cultured in PMA contained negligible PKC-dependent phosphorylation of endogenous substrates or histone, alpha and epsilon PKC isoforms were detected by Western blot analysis. PKC phosphotransferase activity was observed in FD/PMA cells grown in PMA when peptides corresponding to residues 720 to 737 of PKC-epsilon or residues 4 to 14 of myelin basic protein were used as substrates. These data indicate that maintenance of FD/PMA cells in PMA stimulates proliferation and markedly alters PKC substrate specificity. Generation of at least two phospholipid-independent kinases occurs in PMA-treated cells. 相似文献
42.
Negative charge distribution and density on the surface of oxygenated normal and sickle red cells 总被引:2,自引:0,他引:2
Negative charges on the external surface of red cells were visualized by colloidal iron hydroxide labelling of 50% of the membrane area after osmotic hemolysis and glutaraldehyde fixation. Counts were made over randomly selected areas on electron micrographs at 350,000 x magnification. Statistical analyses showed that at the 95% level of confidence there was no significant difference between oxygenated normal (AA) and sickle (SS) cells in either the distribution or the density of negative charges. 相似文献
43.
Erythropoietin structure-function relationships: high degree of sequence homology among mammals 总被引:7,自引:3,他引:4
Wen D; Boissel JP; Tracy TE; Gruninger RH; Mulcahy LS; Czelusniak J; Goodman M; Bunn HF 《Blood》1993,82(5):1507-1516
To investigate structure-function relationships of erythropoietin (Epo), we have obtained cDNA sequences that encode the mature Epo protein of a variety of mammals. A first set of primers, corresponding to conserved nucleotide sequences between mouse and human DNAs, allowed us to amplify by polymerase chain reaction (PCR) intron 1/exon 2 fragments from genomic DNA of the hamster, cat, lion, dog, horse, sheep, dolphin, and pig. Sequencing of these fragments permitted the design of a second generation of species-specific primers. RNA was prepared from anemic kidneys and reverse-transcribed. Using our battery of species-specific 5' primers, we were able to successfully PCR- amplify Epo cDNA from Rhesus monkey, rat, sheep, dog, cat, and pig. Deduced amino acid sequences of mature Epo proteins from these animals, in combination with known sequences for human, Cynomolgus monkey, and mouse, showed a high degree of homology, which explains the biologic and immunological cross-reactivity that has been observed in a number of species. Human Epo is 91% identical to monkey Epo, 85% to cat and dog Epo, and 80% to 82% to pig, sheep, mouse, and rat Epos. There was full conservation of (1) the disulfide bridge linking the NH2 and COOH termini; (2) N-glycosylation sites; and (3) predicted amphipathic alpha- helices. In contrast, the short disulfide bridge (C29/C33 in humans) is not invariant. Cys33 was replaced by a Pro in rodents. Most of the amino acid replacements were conservative. The C-terminal part of the loop between the C and D helices showed the most variation, with several amino acid substitutions, deletions, and/or insertions. Calculations of maximum parsimony for intron 1/exon 2 sequences as well as coding sequences enabled the construction of cladograms that are in good agreement with known phylogenetic relationships. 相似文献
44.
High-affinity RNA-binding domains of alfalfa mosaic virus coat protein are not required for coat protein-mediated resistance. 总被引:1,自引:0,他引:1 下载免费PDF全文
V Yusibov L S Loesch-Fries 《Proceedings of the National Academy of Sciences of the United States of America》1995,92(19):8980-8984
A virus-based vector was used for the transient expression of the alfalfa mosaic virus coat protein (CP) gene in protoplasts and plants. The accumulation of wild-type CP conferred strong protection against subsequent alfalfa mosaic virus infection, enabling the efficacy of CP mutants to be determined without developing transgenic plants. Expression of the CP mRNA alone without CP accumulation conferred weaker protection against infection. The activity of the N-terminal mutant CPs in protection did not correlate with their activities in genome activation. The activity of a C-terminal mutant suggested that encapsidation did not have a role in protection. Our results indicate that interaction of the CP with alfalfa mosaic virus RNA is not important in protection, thereby leaving open the possibility that interactions with host factors lead to protection. 相似文献
45.
46.
Krimer LS; Herman MM; Saunders RC; Boyd JC; Hyde TM; Carter JM; Kleinman JE; Weinberger DR 《Cerebral cortex (New York, N.Y. : 1991)》1997,7(8):732-739
The entorhinal cortex (ERC) has been implicated in schizophrenia by a
number of studies. There is anatomical observation of neuronal heterotopias
in the rostral ERC, which is consistent with a hypothesis of
neurodevelopmental abnormalities in this disease. In view of the
significant cytoarchitectonic variation of the ERC throughout its
rostro-caudal extent, we performed a detailed subareal analysis of the
rostral two-thirds of the entorhinal cortex (ERCr) in 14 postmortem
schizophrenic brains and 14 matched controls (mean ages of 48 and 47
respectively). This systematic evaluation included both a qualitative
microscopic analysis of morphogenetic anomalies that would be consistent
with neurodevelopmental pathology and quantitative measurements of total
neuronal number, average neuronal density, laminar volume and laminar depth
from the cortical surface in cytoarchitectonically matched subareas of
schizophrenic and control brains. Parcellation of the entire ERC on the
basis of cytoarchitectonic criteria identified five distinct regions,
similar to those described in the macaque, except that in the human brain
three of the regions were further divisible into two or three subareas,
yielding nine distinct cellular compartments. Five rostral areas, prorhinal
(Pr), lateral (28L), intermediate rostral and caudal (281r and 281c), and
sulcal (28S), comprise the ERCr. Gross and microscopic examination of these
subdivisions throughout the ERCr failed to reveal laminar disorganization
in any of the schizophrenic brains. The brains also did not differ
significantly with respect to total neuronal number, total volume and
neuronal density per laminar and subareal subdivision, or laminar thickness
per entorhinal subarea. However, neuronal number and density were reduced
by 12-18% in Pr and 28L, suggesting that mild quantitative abnormalities
may exist in the ERCr and might possibly be revealed in a larger sample of
schizophrenic brains. We have failed to confirm previous reports of laminar
disorganization in the ERCr in brains of patients with schizophrenia; to
the extent that this region is implicated in schizophrenia, the structural
changes are likely to consist of more subtle cellular disturbances.
相似文献
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