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111.
Richard M. Franklin Lyman R. Emmons Rebecca P. Emmons Osamu Kai Anna Oommen J. Richard Pink Anne-Marie Rijnbeek Marianne Schnetzler Leena Tuderman Eeva Vainio 《Journal of cellular biochemistry》1984,24(1):1-14
X3, a monoclonal antibody of unusual specificity, is described. This antibody reacts with one or more cytokeratin polypeptides and also reacts with an avian (chicken, quail) nuclear antigen that appears to be present in all cell types (chicken) tested, although with variable staining pattern and intensity. This antigen is distinct from the cytokeratins but does have an epitope in common with this class of proteins. It disappears from the nucleus during the early stages of cell division and reappears during anaphase as a granular cytoplasmic structure. In late telophase the antigen is relocated in the nucleus. This antigen, which we have designated as avian-specific nuclear antigen (AVNA), is not associated with chromatin or ribonucleoproteins. From immunoblotting experiments on chicken fibroblast nuclei, AVNA is probably a complex composed of one or several polypeptides, one of which has a molecular weight of approximately 60 kD. The proteins were identified as nuclear matrix proteins rather than pore complex-lamina proteins by immunoblotting experiments on the purified nuclear matrix of chicken erythrocytes. The major polypeptide had a molecular weight of 60 kD and the minor polypeptide a molecular weight of 69 kD. 相似文献
112.
Although several approaches to the control of human parasites are possible, the prevention and therapy of the corresponding diseases still remain a difficult task. The development of vaccines has been hampered by the poor immunological response to or the high variability of parasitic antigens. Problems also arise for chemotherapy where differences in the biochemistry of host and parasite must be exploited. The increasingly difficult search for new drugs is always challenged by the appearance of resistance. 相似文献
113.
114.
McManus DC Scott BR Franklin V Sparks DL Marcel YL 《The Journal of biological chemistry》2001,276(24):21292-21302
We have devised a combined in vivo, ex vivo, and in vitro approach to elucidate the mechanism(s) responsible for the hypoalphalipoproteinemia in heterozygous carriers of a naturally occurring apolipoprotein A-I (apoA-I) variant (Leu(159) to Arg) known as apoA-I Finland (apoA-I(FIN)). Adenovirus-mediated expression of apoA-I(FIN) decreased apoA-I and high density lipoprotein cholesterol concentrations in both wild-type C57BL/6J mice and in apoA-I-deficient mice expressing native human apoA-I (hapoA-I). Interestingly, apoA-I(FIN) was degraded in the plasma, and the extent of proteolysis correlated with the most significant reductions in murine apoA-I concentrations. ApoA-I(FIN) had impaired activation of lecithin:cholesterol acyltransferase in vitro compared with hapoA-I, but in a mixed lipoprotein preparation consisting of both hapoA-I and apoA-I(FIN) there was only a moderate reduction in the activation of this enzyme. Importantly, secretion of apoA-I was also decreased from primary apoA-I-deficient hepatocytes when hapoA-I was co-expressed with apoA-I(FIN) following infection with recombinant adenoviruses, a condition that mimics secretion in heterozygotes. Thus, this is the first demonstration of an apoA-I point mutation that decreases LCAT activation, impairs hepatocyte secretion of apoA-I, and makes apoA-I susceptible to proteolysis leading to dominantly inherited hypoalphalipoproteinemia. 相似文献
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116.
A full length (192 amino acids) uracil-DNA glycosylase (TMUDG) has been expressed and purified from the extreme thermophile Thermotoga maritima. This protein is active up to 85 degrees C. The enzyme is product inhibited by abasic sites in DNA and weakly inhibited by uracil. TMUDG was originally cloned from an ORF which encoded a protein of 185 amino acids. This shorter protein was stable up to 70-75 degrees C and it seemed unusual that this enzyme had an optimal activity temperature below the growth temperature of the organism (80-90 degrees C). Following the publication of the complete genomic sequence of T. maritima, it was shown that the gene contains an additional seven amino acids (LYTREEL) at the N-terminal end of the protein. It is suggested that these seven residues are important in maintaining proper protein folding that results in increased temperature stability. We have also demonstrated that TMUDG can substitute for the Escherichia coli uracil-DNA glycosylase and initiate base excision repair using a closed circular DNA substrate containing a unique U:G base pair. 相似文献
117.
118.
Purification and characterization of Thermotoga maritima endonuclease IV, a thermostable apurinic/apyrimidinic endonuclease and 3'-repair diesterase
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Haas BJ Sandigursky M Tainer JA Franklin WA Cunningham RP 《Journal of bacteriology》1999,181(9):2834-2839
An endonuclease IV homolog was identified as the product of a conceptual open reading frame in the genome of the hyperthermophilic bacterium Thermotoga maritima. The T. maritima endonuclease IV gene encodes a 287-amino-acid protein with 32% sequence identity to Escherichia coli endonuclease IV. The gene was cloned, and the expressed protein was purified and shown to have enzymatic activities that are characteristic of the endonuclease IV family of DNA repair enzymes, including apurinic/apyrimidinic endonuclease activity and repair activities on 3'-phosphates, 3'-phosphoglycolates, and 3'-trans-4-hydroxy-2-pentenal-5-phosphates. The T. maritima enzyme exhibits enzyme activity at both low and high temperatures. Circular dichroism spectroscopy indicates that T. maritima endonuclease IV has secondary structure similar to that of E. coli endonuclease IV and that the T. maritima endonuclease IV structure is more stable than E. coli endonuclease IV by almost 20 degrees C, beginning to rapidly denature only at temperatures approaching 90 degrees C. The presence of this enzyme, which is part of the DNA base excision repair pathway, suggests that thermophiles use a mechanism similar to that used by mesophiles to deal with the large number of abasic sites that arise in their chromosomes due to the increased rates of DNA damage at elevated temperatures. 相似文献
119.
The Distribution of Microbial Communities in Anaerobic and Aerobic Zones of a Shallow Coastal Plain Aquifer 总被引:2,自引:0,他引:2
Abstract
Randomly amplified polymorphic DNA (RAPD) fingerprinting was used to determine the genetic similarity of whole-community DNA
extracts from unattached microorganisms in several groundwater wells. The study site was a shallow coastal plain aquifer on
the Eastern Shore of Virginia that contains distinct regions of anaerobic and aerobic groundwater. Several wells in each region
were sampled, and principal component and cluster analyses showed a clear separation of the microbial communities from the
two chemical zones of the aquifer. Within these zones, there was no relationship between the genetic relatedness of a pair
of communities and their spatial separation. Two additional sets of samples were taken at later times, and the same clear
separation between communities in the different zones of the aquifer was observed. The specific relationships between wells
within each zone changed over time, however, and the magnitude and direction of these changes corresponded to concurrent changes
in the groundwater chemistry at each well. Together, these results suggest that local variation in groundwater chemistry can
support genetically distinct microbial communities, and that the composition of the microbial communities can follow seasonal
fluctuations in groundwater chemistry.
Received: 25 May 1999; Accepted: 4 August 1999; Online Publication: 9 December 1999 相似文献
120.
Srikanth Sampathkumar Franklin Christopher C. Duke Richard C. Kraft Andrew S. 《Molecular and cellular biochemistry》1999,199(1-2):169-178
Recent studies have suggested that MAP kinase phosphatase 1 (MKP-1) is overexpressed in prostate cancer. To evaluate the role of MKP-1 in regulating cell death and tumor growth in prostate cancer, MKP-1 was conditionally overexpressed in the human prostate cancer cell line DU145. Overexpression of MKP-1 in DU145 cells blocked activation of stress-activated protein kinase (SAPK/JNK). MKP-1 overexpression in DU-145 cells was also found to inhibit Fas ligand (FasL)-induced apoptosis, as well as block the activation of caspases by Fas engagement. In addition, MKP-1 blocked the activation of apoptosis by transfected MEKK-1 and ASK-1, presumably through its inhibition of the SAPK/JNK family of enzymes. MKP-1 blocked the ability of FasL to induce loss of mitochondrial transmembrane potential (m), suggesting that MKP-1 acts upstream of mitochondrial pro-apoptotic events induced by FasL and that the SAPK/JNK pathway may form the signaling link between Fas receptor and mitochondrial dysfunction. Thus, MKP-1 overexpression in prostate cancer may play a role in promoting prostate carcinogenesis by inhibiting FasL-induced cell death. 相似文献