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排序方式: 共有397条查询结果,搜索用时 115 毫秒
1.
The evolution of egg yolk proteins 总被引:13,自引:0,他引:13
2.
Sacco C. de Vries Hilbert Booij Peter Meyerink Gert Huisman H. Dayton Wilde Terry L. Thomas Ab van Kammen 《Planta》1988,176(2):196-204
Embryogenic suspension cultures of domesticated carrot (Daucus carota L.) are characterized by the presence of proembryogenic masses (PEMs) from which somatic embryos develop under conditions of low cell density in the absence of phytohormones. A culture system, referred to as starting cultures, was developed that allowed analysis of the emergence of PEMs in newly initiated hypocotyl-derived suspension cultures. Embryogenic potential, reflected by the number of FEMs present, slowly increased in starting cultures over a period of six weeks. Addition of excreted, high-molecular-weight, heat-labile cell factors from an established embryogenic culture considerably accelerated the acquisition of embryogenic potential in starting cultures. Analysis of [35S]methionine-labeled proteins excreted into the medium revealed distinct changes concomitant with the acquisition of embryogenic potential in these cultures. Analysis of the pattern of gene expression by in-vitro translation of total cellular mRNA from starting cultures with different embryogenic potential and subsequent separation of the [35S]methionine-labeled products by two-dimensional polyacrylamide gel electrophoresis demonstrated a small number of abundant in-vitro-translation products to be present in somatic embryos and in embryogenic cells but absent in nonembryogenic cells. Several other in-vitro-translation products were present in explants, non-embryogenic and embryogenic cells but were absent in somatic embryos. Hybridization of an embryoregulated complementary-DNA sequence, Dc3, to RNA extracted from starting cultures showed that the corresponding gene is expressed in somatic embryos and PEMs but not in non-embryogenic cells.Abbreviations 2,4-D
2,4-dichlorophenoxyacetic acid
- cDNA
complementary DNA
- PAGE
polyacrylamide gel electrophoresis
- PEM
proembryogenic mass 相似文献
3.
4.
Jacques Hille Frank Verheggen Peter Roelvink Henk Franssen Ab van Kammen Pim Zabel 《Plant molecular biology》1986,7(3):171-176
Summary Plant cells are sensitive to the antibiotic bleomycin, a DNA damaging glycopeptide. A bleomycin resistance determinant, located on transposon Tn5 and functional in bacteria, has been cloned in a plant expression vector and introduced into Nicotiana plumbaginifolia using Agrobacterium tumefaciens. The expression of this determinant in plant cells confers resistance to bleomycin and allows selection of transformed plant cells. 相似文献
5.
Anke J. de Jong Theo Hendriks Ellen A. Meijer Maarten Penning Fiorella L. Schiavo Mario Terzi Ab van Kammen Sacco C. de Vries 《Genesis (New York, N.Y. : 2000)》1995,16(4):332-343
At the nonpermissive temperature, somatic embryos of the temperature-sensitive (ts) carrot (Daucus carota L.) cell variant ts11 only proceed beyond the globular embryo stage in the presence of medium conditioned by wild-type cells. The causative component in the conditioned medium has been identified as an acidic 32 kD endochitinase. An antiserum raised against the 32 kD chitinase detected this protein in culture medium from ts11 embryo cultures grown at the permissive temperature as well as at the nonpermissive temperature. No difference in biochemical characteristics or in effect on ts11 embryo development could be detected between the 32 kD chitinase purified from wild-type cultures and the chitinase from ts11 cultures grown at the permissive or at the nonpermissive temperature. Compared to the amount present in a ts11 embryo culture at the permissive temperature, a reduction in the amount of 32 kD chitinase was observed during the temperature-sensitive period at the nonpermissive temperature. These results imply that the arrested embryo phenotype of ts11 is not the result of a structural difference in its 32 kD chitinase, but is the result of a transient decrease in the amount of 32 kD chitinase present. Morphological observations indicate that the ts11 phenotype is pleiotropic and also affects the cell wall of nonembryogenic cells. © 1995 Wiley-Liss, Inc. 相似文献
6.
7.
Enzyme IIBcellobiose of the phosphoenol-pyruvate-dependent phosphotransferase system of Escherichia coli: backbone assignment and secondary structure determined by three-dimensional NMR spectroscopy. 总被引:1,自引:1,他引:0 下载免费PDF全文
E. Ab G. K. Schuurman-Wolters M. H. Saier J. Reizer M. Jacuinod P. Roepstorff K. Dijkstra R. M. Scheek G. T. Robillard 《Protein science : a publication of the Protein Society》1994,3(2):282-290
The assignment of backbone resonances and the secondary structure determination of the Cys 10 Ser mutant of enzyme IIBcellobiose of the Escherichia coli cellobiose-specific phosphoenol-pyruvate-dependent phosphotransferase system are presented. The backbone resonances were assigned using 4 triple resonance experiments, the HNCA and HN(CO)CA experiments, correlating backbone 1H, 15N, and 13C alpha resonances, and the HN(CA)CO and HNCO experiments, correlating backbone 1H,15N and 13CO resonances. Heteronuclear 1H-NOE 1H-15N single quantum coherence (15N-NOESY-HSQC) spectroscopy and heteronuclear 1H total correlation 1H-15N single quantum coherence (15N-TOCSY-HSQC) spectroscopy were used to resolve ambiguities arising from overlapping 13C alpha and 13CO frequencies and to check the assignments from the triple resonance experiments. This procedure, together with a 3-dimensional 1H alpha-13C alpha-13CO experiment (COCAH), yielded the assignment for all observed backbone resonances. The secondary structure was determined using information both from the deviation of observed 1H alpha and 13C alpha chemical shifts from their random coil values and 1H-NOE information from the 15N-NOESY-HSQC. These data show that enzyme IIBcellobiose consists of a 4-stranded parallel beta-sheet and 5 alpha-helices. In the wild-type enzyme IIBcellobiose, the catalytic residue appears to be located at the end of a beta-strand. 相似文献
8.
The NMR side-chain assignments and solution structure of enzyme IIBcellobiose of the phosphoenolpyruvate-dependent phosphotransferase system of Escherichia coli. 总被引:1,自引:1,他引:0 下载免费PDF全文
E. Ab G. Schuurman-Wolters J. Reizer M. H. Saier K. Dijkstra R. M. Scheek G. T. Robillard 《Protein science : a publication of the Protein Society》1997,6(2):304-314
The assignment of the side-chain NMR resonances and the determination of the three-dimensional solution structure of the C10S mutant of enzyme IIBcellobiose (IIBcel) of the phosphoenolpyruvate-dependent phosphotransferase system of Escherichia coli are presented. The side-chain resonances were assigned nearly completely using a variety of mostly heteronuclear NMR experiments, including HCCH-TOCSY, HCCH-COSY, and COCCH-TOCSY experiments as well as CBCACOHA, CBCA(CO)NH, and HBHA(CBCA)(CO)NH experiments. In order to obtain the three-dimensional structure, NOE data were collected from 15N-NOESY-HSQC, 13C-HSQC-NOESY, and 2D NOE experiments. The distance restraints derived from these NOE data were used in distance geometry calculations followed by molecular dynamics and simulated annealing protocols. In an iterative procedure, additional NOE assignments were derived from the calculated structures and new structures were calculated. The final set of structures, calculated with approximately 2000 unambiguous and ambiguous distance restraints, has an rms deviation of 1.1 A on C alpha atoms. IIBcel consists of a four stranded parallel beta-sheet, in the order 2134. The sheet is flanked with two and three alpha-helices on either side. Residue 10, a cysteine in the wild-type enzyme, which is phosphorylated during the catalytic cycle, is located at the end of the first beta-strand. A loop that is proposed to be involved in the binding of the phosphoryl-group follows the cysteine. The loop appears to be disordered in the unphosphorylated state. 相似文献
9.
10.
How is the flagellar length of mature sperm determined? I. Comparison of flagellar growth in spermatids between newt and Xenopus in vitro 总被引:2,自引:0,他引:2
The kinetics of flagellar growth in round spermatids were compared between Xenopus laevis and Cynops pyrrhogaster in vitro, the latter of which has about 13 times longer flagella in mature sperm than the former. In both species, more than 90% of the spermatids derived from marked primary spermatocytes grew flagella. In Xenopus the average flagellar length increased to 28 microns by the 6th day and then stopped growth, while in the newt, flagellar growth did not stop until reaching 107 microns in average on the 10th day. Maximal length was 36-38 microns in Xenopus and 187 microns in the newt. Two major differences in kinetics of flagellar growth were found between the two species. First, the initial rate of growth in the newt was about double the rate in Xenopus. Second, the period of flagellar growth in the newt (10 days) was also about double the period in Xenopus (5-6 days). Actinomycin D (10 micrograms/ml) had no inhibitory effect on flagellar growth in either species, whereas cycloheximide (10 microM) inhibited flagellar growth by more than 80% in both species. These results indicate that translational control presumably of flagellar protein synthesis plays an important role in flagellar growth in both species and in the difference in flagellar length in spermatids between Xenopus and newt. 相似文献