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排序方式: 共有249条查询结果,搜索用时 33 毫秒
1.
Mutations in the E1a gene of type 5 adenovirus result in oncogenic transformation of Fischer rat embryo cells 总被引:1,自引:0,他引:1
G J Duigou L E Babiss W S Liaw S G Zimmer H S Ginsberg P B Fisher 《Journal of cellular biochemistry》1987,33(2):117-126
Transformation of a specific clone of Fischer rat embryo (CREF) cells with wild-type 5 adenovirus (Ad5) or the E1a plus E1b transforming gene regions of Ad5 results in epithelioid transformants that grow efficiently in agar but that do not induce tumors when inoculated into nude mice or syngeneic Fischer rats. In contrast, CREF cells transformed by a host-range Ad5 mutant, H5hrl, which contains a single base-pair deletion of nucleotide 1055 in E1a resulting in a 28-kd protein (calculated) in place of the wild-type 51-kd acidic protein, display a cold-sensitive transformation phenotype and an incomplete fibroblastic morphology but surprisingly do induce tumors in nude mice and syngeneic rats. Tumors develop in both types of animals following injection of CREF cells transformed by other cold-sensitive Ad5 E1a mutants (H5dl101 and H5in106), which contain alterations in their 13S mRNA and consequently truncated 289AA proteins. CREF cells transformed with only the E1a gene (0-4.5 m.u.) from H5hrl or H5dl101 also produce tumors in these animals. To directly determine the role of the 13S E1a encoded 289AA protein and the 12S E1a encoded 243AA protein in initiating an oncogenic phenotype in adenovirus-transformed CREF cells, we generated transformed cell lines following infection with the Ad2 mutant pm975, which synthesizes the 289AA E1a protein but not the 243AA protein, and the Ad5 mutant H5dl520 and the Ad2 mutant H2dl1500, which do not produce the 289AA E1a protein but synthesize the normal 243AA E1a protein. All three types of mutant adenovirus-transformed CREF cells induced tumors in nude mice and syngeneic rats. Tumor formation by these mutant adenovirus-transformed CREF cells was not associated with changes in the arrangement of integrated adenovirus DNA or in the expression of adenovirus early genes. These results indicate, therefore, that oncogenic transformation of CREF cells can occur in the presence of a wild-type 13S E1a protein or a wild-type 12S E1a protein when either protein is present alone, but does not occur when both wild-type E1a proteins are present. 相似文献
2.
Two Lyt-2 polypeptides arise from a single gene by alternative splicing patterns of mRNA 总被引:17,自引:0,他引:17
The Lyt-2/3 molecule is a glycoprotein expressed on T lymphocytes and has classically been considered a marker for the cytotoxic/suppressor T cell subset. It has been postulated to be a receptor for class I major histocompatibility complex proteins. We have used a cDNA clone encoding the analogous human protein, Leu-2/T8, to isolate mouse cDNA clones, which were used as probes to isolate mouse genomic clones. By transfection we have shown that the mouse homologue of Leu-2/T8 is Lyt-2 and not Lyt-3. We have further demonstrated that two Lyt-2 polypeptide chains are encoded by a single gene and result from alternative modes of mRNA splicing. The nucleotide sequence of cDNA clones encoding each of these polypeptide chains has been determined and shows the difference between the two Lyt-2 polypeptide chains to be in the lengths of their cytoplasmic tails. 相似文献
3.
Trace elements and lipid peroxidation in 26 patients with chronic renal failure treated with hemodialysis and 25 healthy subjects
were observed. Both plasma and erythrocyte trace elements and plasma malon dialdehyde (MDA) were examined immediately before
and after hemodialysis. Increased levels of plasma Cu, MDA, and erythrocyte Pb, Mn, Zn, and a significantly decreased plasma
Se, Zn and erythrocyte Se were found in patients before hemodialysis. After a single hemodialysis, erythrocyte Mn, Cu, Zn,
and plasma Cu, Al, and MDA were significantly increased whereas both plasma and erythrocyte Se were lower in patients than
in healthy subjects. The level of MDA was not significantly changed during the single hemodialysis. Both plasma and erythrocyte
Zn levels and plasma Cu and Al were significantly higher after hemodialysis than before hemodialysis. In conclusion, levels
of trace elements are altered by hemodialysis, which may increase patient susceptibility to lipid peroxidation in uremia. 相似文献
4.
C. Goldstein P. Liaw S. A. Jimenez A. M. Buchberg L. D. Siracusa 《Mammalian genome》1994,5(11):696-700
The fibrillin genes, FBN1 and FBN2, encode large extracellular matrix glycoproteins involved in the structure and function of microfibrils. Mutations in FBN1 are found in patients with Marfan syndrome, a heritable connective tissue disease that primarily affects the cardiovascular, ocular, and skeletal systems. We extended the studies of these genes by determining their chromosomal position in the mouse genome. Restriction fragment length polymorphisms (RFLPs) between the progenitors of an interspecific backcross involving AEJ/Gn and Mus spretus mice were used to establish the segregation patterns of the murine homologs, Fbn1 and Fbn2, in the backcross progeny. The results position Fbn1 between the B2m and Illa genes on mouse Chromosome (Chr) 2 and establish its candidacy for the Tight skin (Tsk) mutation. The results position Fbn2 between the D18Mit35 and Pdgfrb loci in the central region of mouse Chr 18. Fbn2 maps near three mutations [bouncy (bc), plucked (pk), and shaker with syndactyly (sy)] and may be a candidate for the pk mutation. 相似文献
5.
A systematic structural comparison of several carp gamma-crystallins with high methionine contents was made by the secondary-structure prediction together with computer model-building based on the established X-ray structure of calf gamma-II crystallin. The overall surface hydrophilicity profile and the distribution of helices, beta-sheets, and beta-turns along the polypeptide chains are very similar among these carp gamma-crystallins. In addition, their general polypeptide packing is close to the characteristic 2 domain/4 motif Greek key three-dimensional conformation depicted for the calf gamma-II crystallin. Interestingly, most hydrophobic methionine residues are located on the protein surface with only a few buried inside the protein surface or in the interface between two motifs of each domain. The exposed hydrophobic and polarizable methionine cluster on the protein surface may have a bearing on the crystallin stability and dense packing in the piscine species, and probably also provides a malleable nonpolar surface for the interaction with other crystallin components for the maintenance of a clear and transparent lens. 相似文献
6.
The molecular and crystal structure of steffimycin have been determined by single crystal X-ray diffraction to 0.9 angstrom resolution. The triclinic crystals are in the space group P1, with the unit cell dimensions of a = 8.606(3) angstrom, b = 22.168(7) angstrom, c = 8.448(2) angstrom, alpha = 97.56(3) degrees, beta = 95.97(2) degrees, gamma = 87.94(3) degrees, Z = 2. The structure was solved by direct methods and refined by the full-matrix least-squares method to a final R value of 0.065 with 3405 (Inet greater than 2.0 sigma (Inet] observed reflections using the NRCVAX software package. The crystal lattice includes 2 independent steffimycin, 3 water and one 2-methyl-2,4-pentanediol molecules. The conformation of steffimycin is grossly similar to other anthracycline antibiotics including daunorubicin. The crystal packing interactions of steffimycin suggest a preferred stacking of the aglycone chromophore of the antibiotic which resembles the intercalative interactions seen in the daunorubicin-d(CGTACG) (Wang et al., Biochemistry 26, 1152 (1987] and nogalamycin-d(CGT(pS)ACG) (Liaw et al., Biochemistry 28, 9913 (1989] complexes. The atomic coordinates data from these complexes were used to model the intercalative binding of steffimycin to DNA. The models were then stereochemically idealized by the constraint refinement program NUCLSQ. Subsequently XPLOR software package was used for energy minimization of these models in vacuo. The model building studies suggest that steffimycin has a higher CpG base sequence specificity over the TpA step, similar to that of daunorubicin and nogalamycin. 相似文献
7.
The three-dimensional molecular structures of the complexes between a novel antitumor drug nogalamycin and its derivative U-58872 with a modified DNA hexamer d[m5CGT(pS)Am5CG] have been determined at 1.7- and 1.8-A resolution, respectively, by X-ray diffraction analyses. Both structures (in space group P6(1)) have been refined with constrained refinement procedure to final R factors of 0.208 (3386 reflections) and 0.196 (2143 reflections). In both complexes, two nogalamycins bind to the DNA hexamer double helix in a 2:1 ratio with the elongated aglycon chromophore intercalated between the CpG steps at both ends of the helix. The aglycon chromophore spans across the GC Watson-Crick base pairs with its nogalose lying in the minor groove and the aminoglucose lying in the major groove of the distorted B-DNA double helix. Most of the sugars remain in the C2'-endo pucker family, except three deoxycytidine residues (terminal C1, C7, and internal C5). All nucleotides are in the anti conformation. Specific hydrogen bonds are found in the complex between the drug and guanine-cytosine bases in both grooves of the helix. One hydroxyl group of the aminoglucose donates a hydrogen bond to the N7 of guanine, while the other receives a hydrogen bond from the N4 amino group of cytosine. The orientation of these two hydrogen bonds suggests that nogalamycin prefers a GC base pair with its aglycon chromophore intercalating at the 5'-side of a guanine (between NpG), or at the 3'-side of a cytosine (between CpN) with the sugars pointing toward the GC base pair. The binding of nogalamycin to DNA requires that the base pairs in DNA open up transiently to allow the bulky sugars to go through, suggesting that nogalamycin prefers GC sequences embedded in a stretch of AT sequences. 相似文献
8.
Irradiation of the kinetochore region of PtK2 chromosomes by laser light of 532 nm was used to study the function of the kinetochore region in chromosome movement and
to create artificial micronuclei in cells. When the sister kinetochores of a chromosome were irradiated at prometaphase, the
affected chromosome detached from the spindle and exhibited no further directed movements for the duration of mitosis. The
chromatids of the chromosome remained attached to one another until anaphase, at which point they separated. No poleward movement
of the chromatids was observed, and at telophase they passively moved to one of the daughter cells and were enclosed in a
micronucleus. The daughter cell containing the micronucleus was then isolated by micromanipulation and followed through subsequent
mitoses. At the next mitosis, two chromosomes, each with two chromatids, condensed in the micronucleus. These chromosomes
did not attach to the spindle and showed chromatid separation, but no poleward movements at anaphase. They were again enclosed
in micronuclei at telophase. The third generation mitosis was similar to the second.
Occasionally, both the irradiation-produced and naturally occurring micronuclei exhibited no chromosome condensation at mitosis.
Feulgenstained monolayers of PtK2 cells with naturally occurring micronuclei showed that some micronuclei stain positive for DNA and others do not. This finding
raises questions about the fate of chromosomes in a micronucleus. 相似文献
9.
Chia-Ching Liaw Yu-Chen Chen Ahmed Eid Fazary Ju-Liang Hsieh Shun-Ying Chen Ching-Te Chien Shiow-Yunn Sheu Yao-Haur Kuo Bor-Luen Chiang Ya-Ching Shen 《Phytochemistry letters》2013,6(3):397-402
A novel C6–C3 prenylated compound, illicarborene A (1), together with illioliganfunone D (2), 1-allyl-3,5-dimethoxy-4-(3-methylbut-2-enyloxy)benzene (3), (?)-illicinone A (4), (?)-illicinone B (5) and (?)-illicinone A derivative (6) was isolated and characterized from the fruits of Illicium arborescens Hayata. Compound 1 possesses a new class of tricyclic 6/6/5 ring system. The structure of 1 was determined by spectroscopic analysis such as 1H–1H COSY, HMQC, HMBC, and NOESY, and confirmed by chemical reaction to yield 7. Compounds 1–5 were found to increase proliferative activity in primary cell culture of osteoblast cells. 相似文献
10.
Antibody amyloidogenesis is the aggregation of soluble proteins into amyloid fibrils that is one of major causes of the failures of humanized antibodies. The prediction and prevention of antibody amyloidogenesis are helpful for restoring and enhancing therapeutic effects. Due to a large number of possible germlines, the existing method is not practical to predict sequences of novel germlines, which establishes individual models for each known germline. This study proposes a first automatic and across-germline prediction method (named AbAmyloid) capable of predicting antibody amyloidogenesis from sequences. Since the amyloidogenesis is determined by a whole sequence of an antibody rather than germline-dependent properties such as mutated residues, this study assess three types of germline-independent sequence features (amino acid composition, dipeptide composition and physicochemical properties). AbAmyloid using a Random Forests classifier with dipeptide composition performs well on a data set of 12 germlines. The within- and across-germline prediction accuracies are 83.10% and 83.33% using Jackknife tests, respectively, and the novel-germline prediction accuracy using a leave-one-germline-out test is 72.22%. A thorough analysis of sequence features is conducted to identify informative properties for further providing insights to antibody amyloidogenesis. Some identified informative physicochemical properties are amphiphilicity, hydrophobicity, reverse turn, helical structure, isoelectric point, net charge, mutability, coil, turn, linker, nuclear protein, etc. Additionally, the numbers of ubiquitylation sites in amyloidogenic and non-amyloidogenic antibodies are found to be significantly different. It reveals that antibodies less likely to be ubiquitylated tend to be amyloidogenic. The method AbAmyloid capable of automatically predicting antibody amyloidogenesis of novel germlines is implemented as a publicly available web server at http://iclab.life.nctu.edu.tw/abamyloid. 相似文献