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排序方式: 共有117条查询结果,搜索用时 375 毫秒
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2.
Julie Gordon Robert Rumpf Samuel L. Shank Dawne Vernon C. William Birky 《Journal of phycology》1995,31(2):312-313
The nuclear Rrn18 gene coding for small-subunit ribosomal RNA was amplified from Chlamydomonas humicola and C. dysosmos. The sequences were identical, in agreement with the combination of these two species under the name C. applanata on morphological and physiological grounds by Ettl and Schlösser (1992). 相似文献
3.
E1A 12S and 13S of the transformation-defective adenovirus type 12 strain CS-1 inactivate proteins of the RB family, permitting transactivation of the E2F-dependent promoter. 总被引:1,自引:0,他引:1
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The transformation-defective Vero cell host range mutant CS-1 of the highly oncogenic adenovirus type 12 (Ad12) (Ad12-CS-1) has a 69-bp deletion in the early region 1A (E1A) gene that removes the carboxy-terminal half of conserved region 2 and the amino-terminal half of the Ad12-specific so-called spacer that seems to play a pivotal role in the oncogenicity of the virus. Despite its deficiency in immortalizing and transforming primary rodent cells, we found that the E1A 13S protein of Ad12-CS-1 retains the ability to bind p105-RB, p107, and p130 in nuclear extract binding assays with glutathione S-transferase-E1A fusion proteins and Western blot analysis. Like wild-type E1A, the mutant protein was able to dissociate E2F from retinoblastoma-related protein-containing complexes, as judged from gel shift experiments with purified 12S and 13S proteins from transfection experiments with an E1A expression vector or from infection with the respective virus. Moreover, in transient expression assays, the 12S and 13S products of wild-type Ad12 and Ad12-CS-1 were shown to transactivate the Ad12 E1A promoter containing E2F-1 and E2F-5-motifs, respectively, in a comparable manner. The same results were obtained from transfection assays with the E2F motif-dependent E2 promoter of adenovirus type 5 or the human dihydrofolate reductase promoter. These data suggest that efficient infection by Ad12 and the correlated virus-induced reprogramming of the infected cells, including the induction of cell cycle-relevant mechanisms (e.g. E2F activation), can be uncoupled from the transformation properties of the virus. 相似文献
4.
A highly conserved nuclear gene for low-level phylogenetics: elongation factor-1 alpha recovers morphology-based tree for heliothine moths 总被引:8,自引:2,他引:6
Cho S; Mitchell A; Regier JC; Mitter C; Poole RW; Friedlander TP; Zhao S 《Molecular biology and evolution》1995,12(4):650-656
Molecular systematists need increased access to nuclear genes. Highly
conserved, low copy number protein-encoding nuclear genes have attractive
features for phylogenetic inference but have heretofore been applied mostly
to very ancient divergences. By virtue of their synonymous substitutions,
such genes should contain a wealth of information about lower-level
taxonomic relationships as well, with the advantage that amino acid
conservatism makes both alignment and primer definition straightforward. We
tested this postulate for the elongation factor-1 alpha (EF-1 alpha) gene
in the noctuid moth subfamily Heliothinae, which has probably diversified
since the middle Tertiary. We sequenced 1,240 bp in 18 taxa representing
heliothine groupings strongly supported by previous morphological and
allozyme studies. The single most parsimonious gene tree and the
neighbor-joining tree for all nucleotides show almost complete concordance
with the morphological tree. Homoplasy and pairwise divergence levels are
low, transition/transversion ratios are high, and phylogenetic information
is spread evenly across gene regions. The EF-1 alpha gene and presumably
other highly conserved genes hold much promise for phylogenetics of
Tertiary age eukaryote groups.
相似文献
5.
Cultured chick embryo fibroblasts derived from skin and skeletal muscle exhibit hyaluronidase activity both associated with the cell layer and secreted into the medium. Although both forms of the enzyme have a number of similar characteristics (R.W. Orkin and B.P. Toole, 1980, J. Biol. CHem. 255), they differ in thermal stability at neutral pH and in behavior on ion-exchange chromatography. Both forms of the enzyme are equally stable at acidic pH for long intervals, but the cell-associated hyaluronidase is significantly less stable than the secreted froms at neutral pH and at temperatures more than or equal to 30 degrees C. Neither the presence of proteases nor inhibitors of hyaluronidase appear to be involved in the cell-asspcoated enzyme. Chromatography of the two forms of hyaluronidase on carboxymethyl cellulose reveals that most (60-90 percent) of the secreted form of the enzyme elutes at a lower ionic strength than the cell- associated enzyme. Treatment of the secreted form of hyaluronidase with neuraminidase shifts its elution profile on carboxymethyl cellulose toward that of the cell-associated form, and also decreases its thermal stability at neutral pH. In contrast, treatment of the secreted form of hyaluronidase with alkaline phosphatase has no detectable effect. These data suggest that the secreted hyaluronidase differs from the cellular form in possessing additional sialic acid residues which endow the former with increased stability in the extracellular milieu. 相似文献
6.
A PBX1 transcriptional network controls dopaminergic neuron development and is impaired in Parkinson's disease
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J Carlos Villaescusa Bingsi Li Enrique M Toledo Pia Rivetti di Val Cervo Shanzheng Yang Simon RW Stott Karol Kaiser Saiful Islam Daniel Gyllborg Rocio Laguna‐Goya Michael Landreh Peter Lönnerberg Anna Falk Tomas Bergman Roger A Barker Sten Linnarsson Licia Selleri Ernest Arenas 《The EMBO journal》2016,35(18):1963-1978
7.
The present study was to verify the incidence of bovine diploid oocytes when vitrified at various maturation stages. Bovine cumulus-oocyte complexes were recovered from ovaries at a slaughterhouse and then divided into five groups: control group (unvitrified oocytes), 0 h group (composed of oocytes vitrified before the onset of maturation) and 8, 12, and 22 h groups (vitrified respectively at 8, 12 and 22 h after the onset of maturation). The oocytes remained vitrified for 24 h, and then were thawed. In all groups, the oocytes completed 24 h of maturation. Subsequently, the cumulus cells were removed, and the denuded oocytes fixed on slides and stained with aceto-orcein. No differences (P>0.05) in the incidence of diploid metaphase II oocytes were observed between the control, non-vitrified group (2.4%, 1/41) and oocytes vitrified at 12 h (6.9%, 3/43) or 22 h (2%, 1/50). However, significantly (P<0.05) more diploid oocytes were detected after vitrification at 0 h (28.5%, 10/35) or 8 h (35.4%, 11/31) of maturation. These results suggest that the nuclear stage at which bovine oocytes are vitrified may affect the incidence of diploid oocytes, especially in oocytes vitrified before maturation or 8 h after the onset of maturation. 相似文献
8.
The present study aimed to evaluate viability and in vitro fertilizing ability of cryopreserved epididymal spermatozoa obtained from dead animals. To collect spermatozoa, epididymides from three males (Bulls A1, A2 and A3) were collected at a local slaughterhouse. As a reference ejaculate from a bull with known in vitro fertility, was used. Sperm characteristics (motility, chromatin and acrosome integrity) were evaluated before and after cryopreservation. Then, frozen spermatozoa from all animals were used for in vitro fertilization. Cleavage and blastocyst rates at 48 h (day 2) and 168 h (day 7) post in vitro insemination, for bull A1 (82.1 and 38.6%) and A2 (80.7 and 33.8%) were similar (P>0.05) to the reference bull (88.9 and 57.2%). Bull A3 had the lesser cleavage (42.0%) and blastocyst (26.1%) rates. The results showed that epididymal spermatozoa from dead animals can be successfully cryopreserved and used in vitro production of embryos. 相似文献
9.
10.
Gregan J Rabitsch PK Rumpf C Novatchkova M Schleiffer A Nasmyth K 《Nature protocols》2006,1(5):2457-2464
We have designed the most efficient strategy to knock out genes in fission yeast Schizosaccharomyces pombe on a large scale. Our technique is based on knockout constructs that contain regions homologous to the target gene cloned into vectors carrying dominant drug-resistance markers. Most of the steps are carried out in a 96-well format, allowing simultaneous deletion of 96 genes in one batch. Based on our knockout technique, we designed a strategy for cloning knockout constructs for all predicted fission yeast genes, which is available in a form of a searchable database http://mendel.imp.ac.at/Pombe_deletion/. We validated this technique in a screen where we identified novel genes required for chromosome segregation during meiosis. Here, we present our protocol with detailed instructions. Using this protocol, one person can knock out 96 S. pombe genes in 8 days. 相似文献