全文获取类型
收费全文 | 1667篇 |
免费 | 35篇 |
国内免费 | 130篇 |
出版年
2024年 | 1篇 |
2023年 | 6篇 |
2022年 | 5篇 |
2021年 | 11篇 |
2020年 | 8篇 |
2019年 | 14篇 |
2018年 | 6篇 |
2017年 | 12篇 |
2016年 | 16篇 |
2015年 | 27篇 |
2014年 | 47篇 |
2013年 | 46篇 |
2012年 | 48篇 |
2011年 | 37篇 |
2010年 | 37篇 |
2009年 | 46篇 |
2008年 | 44篇 |
2007年 | 62篇 |
2006年 | 50篇 |
2005年 | 61篇 |
2004年 | 67篇 |
2003年 | 61篇 |
2002年 | 47篇 |
2001年 | 36篇 |
2000年 | 50篇 |
1999年 | 81篇 |
1998年 | 84篇 |
1997年 | 88篇 |
1996年 | 53篇 |
1995年 | 71篇 |
1994年 | 57篇 |
1993年 | 51篇 |
1992年 | 59篇 |
1991年 | 65篇 |
1990年 | 67篇 |
1989年 | 43篇 |
1988年 | 35篇 |
1987年 | 45篇 |
1986年 | 38篇 |
1985年 | 48篇 |
1984年 | 36篇 |
1983年 | 12篇 |
1982年 | 14篇 |
1981年 | 11篇 |
1980年 | 8篇 |
1979年 | 7篇 |
1978年 | 5篇 |
1977年 | 4篇 |
1976年 | 3篇 |
1970年 | 2篇 |
排序方式: 共有1832条查询结果,搜索用时 15 毫秒
1.
Mutants and mobilizing plasmids were developed as genetic tools in Alcaligenes eutrophus CH34. In order to map the chromosome, spontaneous and ethyl methane sulphonate (EMS)-induced mutants (mostly auxotrophs) were isolated. Another source of mutants was provided by the phenomenon of temperature-induced mortality and mutagenesis that is observed at 37° C and is characteristic of many metallotolerant strains of A. eutrophus. Plasmid pULB113 (RP4::miniMu) was used to map the available mutations. Twenty-five loci were ordered in a circular map. pMOL50, a rearranged derivative of plasmid pMOL28, which was obtained in a survivor at 37° C and displayed chromosome mobilizing activity (Cma+), was also used to mobilize chromosomal markers: resulting linkages were stronger than with pULB113, allowing confirmation of the circularity of the A. eutrophus CH34 chromosome with a small number of crosses. 相似文献
2.
Chang-Young Jang Judith A. Coppinger Guowei Fang 《Biochemical and biophysical research communications》2010,393(2):259-179
DDA3 is a microtubule-associated protein that controls chromosome congression and segregation by regulating the mitotic spindle. Depletion of DDA3 alters spindle structure, generates unaligned chromosomes at metaphase, and delays the mitotic progression. Through a mass spectrometry analysis, we found that DDA3 is phosphorylated on Ser225 during mitosis. Phosphorylation of this residue is important for the mitotic function of DDA3, as the phospho-mimicking DDA3-S225D variant, but not the nonphosphorable DDA3-S225A mutant, rescues the DDA3-knockdown phenotype. We conclude that the mitotic function of DDA3 is regulated by phosphorylation on the Ser225 residue. 相似文献
3.
Gerhard Pils 《Plant Systematics and Evolution》1985,149(1-2):19-45
The differences betweenFestuca vivipara (tetraploid) andF. ovina subsp.supina (diploid), two often confused taxa, are demonstrated in regard to morphology, leaf anatomy, ecology and distribution. New maps illustrate the distribution ofF. vivipara in the Alps and the Northern Hemisphere. The development of different polyploidy levels withinF. vivipara as a consequence of occasional sexual processes is discussed. (English Summary on p. 39.) 相似文献
4.
Z. Ouanes I. Ayed-Boussema T. Baati E.E. Creppy H. Bacha 《Mutation Research - Genetic Toxicology and Environmental Mutagenesis》2005,565(2):139-149
The cytogenetic effect of zearalenone (ZEN), a non-steroidal estrogenic mycotoxin, was evaluated in vivo, in mouse bone marrow cells, by assessing the percentage of cells bearing different chromosome aberrations. The studies included different conditions for animal treatment, as follows: (1) single intraperitoneal (ip) injection, (2) repeated ip injections, (3) pre-treatment for 24 h with Vitamin E (Vit E), and (4) pre-treatment for 4 h with 17β-estradiol (17β-Est) or progesterone (Prog). ZEN induced different types of chromosome aberrations, which was concentration-dependent (2–20 mg/kg bw). These doses corresponded to 0.4–4% of the LD50 in the mouse. Interestingly, when the dose of ZEN (40 mg/kg) was fractionated into four equivalent doses (4 × 10 mg/kg bw), into three doses (15 + 10 + 15 mg/kg bw), or into two equivalent doses (2 × 20 mg/kg bw), given every 24 h, the percentage of chromosome aberrations increased significantly. This finding suggests that ZEN proceeds by reversible binding on receptors that could become saturated, and that it damages the chromosomes in a ‘hit and go’ manner. Furthermore, pre-treatment of animals with 17β-estradiol or progesterone significantly decreased the percentage of chromosome aberrations, suggesting that (i) these hormones bind to the same cytoplasmic receptors transported into the nucleus to elicit DNA damage, (ii) they may play a role in preventing chromosome aberrations induced by ZEN. Similarly, Vit E prevented these chromosome aberrations indicating that Vit E, previously reported to prevent most of the toxic effects induced by ZEN, may also bind to the same receptors. 相似文献
5.
Molecular cytogenetic characterization of Roegneria ciliaris chromosome additions in common wheat 总被引:2,自引:0,他引:2
X. E. Wang P. D. Chen D. J. Liu P. Zhang B. Zhou B. Friebe B. S. Gill 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2001,102(5):651-657
The development of alien addition lines is important both for transferring useful genes from related species into common wheat and for studying the relationship between alien chromosomes and those of wheat. Roegneria ciliaris (2n=4x=28, ScScYcYc) is reported to be a potential source of resistance to wheat scab, which may be useful in wheat improvement. The amphiploid common wheat-R. ciliaris and BC1F7 or BC2F6 derivatives were screened by C-banding, genomic in situ hybridization (GISH), fluorescent in situ hybridization (FISH) and restriction fragment length polymorphism (RFLP) for the presence of R. ciliaris chromatin introgressed into wheat. Six lines were identified as disomic chromosome additions (DA), one as a ditelosomic addition (Dt), two as double disomic additions (dDA) and one as a monosomic chromosome addition (MA). RFLP analysis using wheat homoeologous group-specific clones indicated that the R. ciliaris chromosomes involved in these lines belong to groups 1, 2, 3, 5 and 7. The genomic affinities of the added R. ciliaris chromosomes were determined by FISH analysis using the repetitive sequence pCbTaq4.14 as a probe. These data suggest that the R. ciliaris chromosomes in five lines belong to the Sc genome. Based on the molecular cytogenetic data, the lines are designated as DA2Sc#1, Dt2Sc#1L, DA3Sc#1, dDA1Sc#2+5Yc#1, DA5Yc#1, DA7Sc#1, DA7Yc#1 and MA?Yc#1. Based on the present and previous work, 8 of the 14 chromosomes of R. ciliaris have been transferred into wheat. 相似文献
6.
B. Maestra T. Naranjo 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1999,98(5):744-750
Chromosome pairing at metaphase-I was analyzed in F1 hybrids among T. turgidum (AABB), T. aestivum (AABBDD), and T. timopheevii (AtAtGG) to study the chromosome structure of T. timopheevii relative to durum (T. turgidum) and bread (T. aestivum) wheats. Individual chromosomes and their arms were identified by means of C-banding. Homologous pairing between the A-genome
chromosomes was similar in the three hybrid types AAtBG, AAtBGD, and AABBD. However, associations of B-G were less frequent than B-B. Homoeologous associations were also observed, especially
in the AAtBGD hybrids. T. timopheevii chromosomes 1At, 2At, 5At, 7At, 2G, 3G, 5G, and 6G do not differ structurally from their counterpart in the A and B genomes. Thus, these three polyploid
species inherited translocation 5AL/4AL from the diploid A-genome donor. Chromosome rearrangements that occurred at the tetraploid
level were different in T. turgidum and T. timopheevii. Translocation 4AL/7BS and a pericentric inversion of chromosome 4A originated only in the T. turgidum lineage. The two lines of T. timophevii studied carry four different translocations, 6AtS/1GS, 1GS/4GS, 4GS/4AtL, and 4AtL/3AtL, which most likely arose in that sequence. These structural differences support a diphyletic origin of polyploid wheats.
Received: 15 June 1998 / Accepted: 19 August 1998 相似文献
7.
Protamine amount and cross linking in mouse teratospermatozoa and aneuploid spermatozoa 总被引:1,自引:0,他引:1
The level of SH-group oxidation in spermatozoa from the cauda epididymis was measured by a cytofluorometric method in chromosomally normal mice and two chromosome mutants. The first one, a tertiary trisomic karyotype (Ts(1(13]7OH), is characterized by severe oligospermia and high levels (approximately 75%) of malformed spermatozoa. The second, a hybrid between two European feral mouse stocks, is heterozygous for multiple Robertsonian translocations and produces exclusively aneuploid spermatozoa. Neither the severe teratospermiogenesis nor the severe aneuploidy was reflected in total SH-group fluorescence values nor in free SH-group fluorescence. It is concluded that both the production of protamines and protamine cross linking by S-S bridge formation are rather autonomous processes during spermatogenesis because 1) the increased DNA variance of the aneuploid spermatozoa is not reflected in an increased variance of the total and free SH-groups, 2) aneuploidy for the protamine gene carrying chromosome 16 is not reflected by the SH-group values for individual spermatozoa, and 3) protamine production and cross linking are independent of the mild to severe terataspermiogenesis in the tertiary trisomic karyotype. 相似文献
8.
Mercedes Soriano Luis Cistué María P. Vallés Ana M. Castillo 《Plant Cell, Tissue and Organ Culture》2007,91(3):225-234
The aim of this work was to study the effects of colchicine application on chromosome doubling and androgenic response in
anther and microspore culture of different bread wheat genotypes. Colchicine was applied during a mannitol stress pretreatment
or during the first 48 h of culture at concentrations of 0, 150 and 300 mg l−1. When colchicine was applied during stress pretreatment, the percentage of doubling depended on genotype and concentration.
A significant increase in doubling was observed with 300 mg l−1 in the low androgenic responding cv. Caramba. Colchicine incorporation during the first hours of culture improved percentage
of doubling in all genotypes, in both anther and microspore culture. Application of 300 mg l−1 colchicine improved the percentage of doubling in the two low responding genotypes, to 118% of control in DH24033, and 75%
in Caramba in microspore and anther culture, respectively. Concerning the androgenic response, the effect of colchicine on
embryo formation and percentage of green plants depended on the genotype and on the culture method. In cv. Pavon, a 2- and
a 3-fold increase in percentage of embryogenesis and green plants, respectively, were obtained with 300 mg l−1 colchicine in microspore culture. However, no significant differences in these two variables were observed in anther culture.
The number of green doubled haploid (DH) plants reflects the index of success of the procedure. Regardless of the culture
method, when colchicine was incorporated during the first hours of culture, the number of green DH plants increased significantly
in three of four genotypes. These results confirm the usefulness of colchicine application during the first hours of culture
in wheat breeding programs. 相似文献
9.
A. M. Carr S. M. Dorrington J. Hindley G. A. Phear S. J. Aves P. Nurse 《Molecular & general genetics : MGG》1994,245(5):628-635
We have isolated and characterised the pht1 gene from the fission yeast Schizosaccharomyces pombe. The sequence of the predicted translation product has revealed a striking similarity to the family of H2A.F/Z histone variant proteins, which have been found in a variety of different organisms. Cells deleted for the pht1 gene locus grow slowly, exhibit an altered colony morphology, increased resistance to heat shock and show a significant decrease in the fidelity of segregation of an S. pombe minichromosome. We propose that the histone H2A variant encoded by the pht1 gene is important for chromosomal structure and function, possibly including a role in controlling the fidelity of chromosomal segregation during mitosis. 相似文献
10.
SHINOBU AKIYAMA MICHIO WAKABAYASHI HIDEAKI OHBA F.L.S. 《Botanical journal of the Linnean Society. Linnean Society of London》1992,109(2):247-257
AKIYAMA, S., WAKABAYASHI, M. & OHBA, H., 1992. Chromosome evolution in Himalayan Impatiens (Balsaminaceae). Chromosome numbers and karyotypes have been investigated in species of Himalayan Impatiens . In addition to confirming previous chromosome counts, the presence of a tetraploid taxon ( I. exilis) is revealed. In central and east Nepal species with x = 9 are more common than those with other basic numbers and this number is shown to be one of the most frequent numbers in the genus. Most species with x = 9 have a bimodal karyotype. The species relationships are discussed. 相似文献