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51.
Eggs differ widely in their ability to develop into an embryo. To address this characteristic, the concept of developmental competency has been coined, defined as the ability or potential of an oocyte to undergo maturation, fertilization and development to blastocyst stages or live offspring. Developmental competency is acquired progressively during folliculogenesis and is linked to follicular size. In an effort to understand the molecular changes underlying differences in competency we compared oocytes derived from large follicles (>or=5mm) to those from small follicles (相似文献
52.
Maize (Zea mays L.) leaf acetyl-CoA carboxylase (ACCase) was purified about 500-fold by ammonium sulfate fractionation and gel filtration and blue Sepharose affinity and anion-exchange chromatography. Most ACCase activity (85%) recovered from the anion-exchange column was found in a highly purified fraction (specific activity 5.5 [mu]mol acid-stable product min-1 mg-1) that consisted primarily of a single 227-kD biotinylated polypeptide. The fraction represented 29% of the original activity and was designated ACCase I. A second partially purified ACCase activity (ACCase II) eluted earlier during anion-exchange chromatography, contained a single biotinylated polypeptide of 219 kD, was poorly recognized by antiserum raised against the ACCase I polypeptide, and was less inhibited by the herbicides haloxyfop or sethoxydim than was ACCase I. ACCase I and II both utilized propionyl-CoA as substrate about 50% as effectively as acetyl-CoA, and neither utilized methylcrotonyl-CoA. Immunoprecipitation with antiserum and protein blotting of crude extracts of leaf, embryo, and endosperm tissue and suspension cells indicated that most ACCase activity in these tissues was immunologically similar and consisted of ACCase I. Only leaves contained significant amounts of the ACCase II polypeptide; however, no ACCase II polypeptide was found in isolated mesophyll chloroplasts. The ACCase I and II polypeptides appear to be subunits of distinct ACCase isoforms. 相似文献
53.
Expression of the Acc1 Gene-Encoded Acetyl-Coenzyme A Carboxylase in Developing Maize (Zea mays L.) Kernels 下载免费PDF全文
Somers DA Keith RA Egli MA Marshall LC Gengenbach BG Gronwald JW Wyse DL 《Plant physiology》1993,101(3):1097-1101
A mutation (Acc1-S2) in the structural gene for maize (Zea mays L.) acetyl-coenzyme A carboxylase (ACCase) that significantly reduces sethoxydim inhibition of leaf ACCase activity was used to investigate the gene-enzyme relationship regulating ACCase activity during oil deposition in developing kernels. Mutant embryo and endosperm ACCase activities were more than 600-fold less sensitive to sethoxydim inhibition than ACCase in wild-type kernel tissues. Moreover, in vitro cultured mutant kernels developed normally in the presence of sethoxydim concentrations that inhibited wild-type kernel development. The results indicate that the Acc1-encoded ACCase accounts for the majority of ACCase activity in developing maize kernels, suggesting that Acc1-encoded ACCase functions not only during membrane biogenesis in leaves but is also the predominant form of ACCase involved in storage lipid biosynthesis in maize embryos. 相似文献
54.
Michael D. Woodrow Stuart P. Ballantine Michael D. Barker Beth J. Clarke John Dawson Tony W. Dean Christopher J. Delves Brian Evans Sharon L. Gough Steven B. Guntrip Stuart Holman Duncan S. Holmes Michael Kranz Mika K. Lindvaal Fiona S. Lucas Margarete Neu Lisa E. Ranshaw Yemisi E. Solanke Don O. Somers Peter Ward Joanne O. Wiseman 《Bioorganic & medicinal chemistry letters》2009,19(17):5261-5265
Crystallography driven optimisation of a lead derived from similarity searching of the GSK compound collection resulted in the discovery of quinoline-3-carboxamides as highly potent and selective inhibitors of phosphodiesterase 4B. This series has been optimized to GSK256066, a potent PDE4B inhibitor which also inhibits LPS induced production of TNF-α from isolated human peripheral blood mononuclear cells with a pIC50 of 11.1. GSK256066 also has a suitable profile for inhaled dosing. 相似文献
55.
Genotoxic air pollution is ubiquitous in urban and industrial areas. A variety of studies has linked human exposure to air
pollution with a number of different somatic cell endpoints including cancer. However, the potential for inducing mutations
in the human germline remains unclear. Sentinel animal studies of germline mutations at tandem-repeat loci (specifically minisatellites
and expanded simple tandem repeats) have recently provided proof of principle that germline mutations can be induced in vertebrates
(birds and mice) by air pollution under ambient conditions. Although humans may also be susceptible to induced germline mutations
in polluted areas, uncertainties regarding causative agents, doses, and mutational mechanisms at repetitive DNA loci currently
preclude extrapolation from animal data to the evaluation of human risk. Nevertheless, several recent studies have linked
air pollution exposure to DNA damage in human sperm, indicating that our germ cells are not impervious to the genotoxic effects
of air pollution. Thus, both sentinel animal and human studies have raised the possibility that ambient air pollution may
increase human germline mutation rates, especially at repetitive DNA loci. Given that some human genetic conditions appear
to be modulated by length mutations at tandem-repeat loci (e.g. HRAS1 cancers, type 1 diabetes, etc.), there is an urgent need for extensive study in this area. Research should be primarily focused
upon: (1) the direct measurement of mutation frequencies at repetitive DNA loci in human male germ cells as a function of
air pollution exposure, (2) large-scale epidemiology studies of inherited disorders and tandem-repeat associated genetic conditions
and air pollution, and (3) the characterization of mutational mechanisms at hypervariable tandem-repeat loci.
相似文献
Christopher M. SomersEmail: |
56.
Growth of high quality crystals is often the most difficult step in the determination of protein structures by X-ray diffraction. Automation can improve the success of this process both by reducing the amount of protein required for each screen and by relieving the tedium of setting up crystallization experiments by hand. We have been using an automated system for the design and execution of hanging drop crystallization experiments for the last two years. The system includes robots for the preparation of solutions, setup of hanging drops, and automated imaging, as well as a new software package (RoCKS) for managing all phases of the crystallization process. Here, we review the fundamentals of automated protein crystallization and present results from our comparisons of various approaches to screening. 相似文献
57.
Svitashev SK Pawlowski WP Makarevitch I Plank DW Somers DA 《The Plant journal : for cell and molecular biology》2002,32(4):433-445
To more fully characterize the internal structure of transgene loci and to gain further understanding of mechanisms of transgene locus formation, we sequenced more than 160 kb of complex transgene loci in two unrelated transgenic oat (Avena sativa L.) lines transformed using microprojectile bombardment. The transgene locus sequences from both lines exhibited extreme scrambling of non-contiguous transgene and genomic fragments recombined via illegitimate recombination. A perfect direct repeat of the delivered DNA, and inverted and imperfect direct repeats were detected in the same transgene locus indicating that homologous recombination and synthesis-dependent mechanism(s), respectively, were also involved in transgene locus rearrangement. The most unexpected result was the small size of the fragments of delivered and genomic DNA incorporated into the transgene loci via illegitimate recombination; 50 of the 82 delivered DNA fragments were shorter than 200 bp. Eleven transgene and genomic fragments were shorter than the DNA lengths required for Ku-mediated non-homologous end joining. Detection of these small fragments provided evidence that illegitimate recombination was most likely mediated by a synthesis-dependent strand-annealing mechanism that resulted in transgene scrambling. Taken together, these results indicate that transgene locus formation involves the concerted action of several DNA break-repair mechanisms. 相似文献
58.
Ouedraogo R Becker B Boverie S Somers F Antoine MH Pirotte B Lebrun P de Tullio P 《Biological chemistry》2002,383(11):1759-1768
A series of 2-alkyl-3-alkylamino-2H-benzo- and 2-alkyl-3-alkylamino-2H-pyrido[4,3-e]-1,2,4-thiadiazine 1,1-dioxides, structurally related to BPDZ 44 and BPDZ 73, two potent pancreatic B-cells K+ATP channel openers, were synthesized and tested on rat pancreatic islets (endocrine tissue) as well as on rat aorta rings (vascular smooth muscle tissue). Alkylation of the 2-position led to double bond tautomerization and formation of compounds with a 2H-conformation. In contrast to the previously described pyridothiadiazine dioxides, such as BPDZ 44, and 7-chlorobenzothiadiazine dioxides, such as BPDZ 73, the 2-alkyl-substituted analogs were found to be poorly active on the insulin releasing process although most drugs exhibited a vasorelaxant activity. As a result, the new 2-alkyl-substituted pyridinic compounds expressed a selectivity profile (vascular smooth muscle tissue vs pancreatic tissue) opposite to that of their non-alkyl-substituted counterparts, i.e. BPDZ 44. Additional investigations revealed that, in contrast to their non 2-alkyl-substituted analogs, the most interesting 2-methyl-substituted derivatives did not express the pharmacological profile of classical K+ATP channel openers. The pharmacological results rather suggest that alkylation of the 2-position of the thiadiazine ring led to drugs that could act as Ca2+ channel blockers rather than as potassium channel openers. 相似文献
59.
60.
Expression of IFI 16 in epithelial cells and lymphoid tissues 总被引:3,自引:1,他引:2