全文获取类型
收费全文 | 3763篇 |
免费 | 222篇 |
国内免费 | 195篇 |
专业分类
4180篇 |
出版年
2024年 | 3篇 |
2023年 | 52篇 |
2022年 | 48篇 |
2021年 | 98篇 |
2020年 | 65篇 |
2019年 | 82篇 |
2018年 | 94篇 |
2017年 | 74篇 |
2016年 | 108篇 |
2015年 | 109篇 |
2014年 | 145篇 |
2013年 | 178篇 |
2012年 | 119篇 |
2011年 | 123篇 |
2010年 | 86篇 |
2009年 | 147篇 |
2008年 | 151篇 |
2007年 | 179篇 |
2006年 | 190篇 |
2005年 | 163篇 |
2004年 | 133篇 |
2003年 | 138篇 |
2002年 | 146篇 |
2001年 | 145篇 |
2000年 | 122篇 |
1999年 | 124篇 |
1998年 | 134篇 |
1997年 | 147篇 |
1996年 | 111篇 |
1995年 | 90篇 |
1994年 | 92篇 |
1993年 | 82篇 |
1992年 | 61篇 |
1991年 | 54篇 |
1990年 | 46篇 |
1989年 | 35篇 |
1988年 | 38篇 |
1987年 | 37篇 |
1986年 | 33篇 |
1985年 | 34篇 |
1984年 | 41篇 |
1983年 | 19篇 |
1982年 | 41篇 |
1981年 | 19篇 |
1980年 | 13篇 |
1979年 | 13篇 |
1978年 | 4篇 |
1977年 | 4篇 |
1976年 | 8篇 |
1974年 | 1篇 |
排序方式: 共有4180条查询结果,搜索用时 15 毫秒
51.
Y. Eshed D. Zamir 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1994,88(6-7):891-897
RFLP-defined chromosome segments covering the entire tomato genome were introgressed from the wild green-fruited speciesLycopersicon pennellii into the cultivated tomato (L. esculentum cv M82; Eshed et al. 1992). SixL. pennellii chromosome segments were selected for a detailed evaluation based on previous observations of their effects on the two yield components, fresh tomato yield and total soluble-solids content (Brix). Differences in the quantitative traits measured between M82 and the introgression lines, or their hybrids with different inbred parents, can be attributed to the alien chromosome segments. Replicated field trials, grown at wide and dense spacing, identified three quantitative trait loci (QTLs) for solublesolids content on chromosomes 1, 5 and 7. In plants heterozygous for the chromosome-5 locus there was a 50% increase in soluble-solids yield in wide but not in dense spacing. Plants heterozygous for the chromosome-1 QTL/s were tested over a 2-year period, in three genetic backgrounds, and showed a significant 16% elevation in soluble-solids yield only in dense spacing. These results demonstrate that wild tomato germplasm can be used to improve the yield of the cultivated crop. 相似文献
52.
M. J. Kearsey V. Hyne 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1994,89(6):698-702
A method to locate quantitative trait loci (QTL) on a chromosome and to estimate their additive and dominance effects is described. It applies to generations derived from an F1 by selfing or backcrossing and to doubled haploid lines, given that marker genotype information (RFLP, RAPD, etc.) and quantitative trait data are available. The method involves regressing the additive difference between marker genotype means at a locus against a function of the recombination frequency between that locus and a putative QTL. A QTL is located, as by other regression methods, at that point where the residual mean square is minimised. The estimates of location and gene effects are consistent and as reliable as conventional flanking-marker methods. Further applications include the ability to test for the presence of two, or more, linked QTL and to compare different crosses for the presence of common QTL. Furthermore, the technique is straightforward and may be programmed using standard pc-based statistical software. 相似文献
53.
54.
本文给出了方程dx/dt=f(x(t-1))出现4/(2n 1),4/(2n-1),4/(2n-3),…,4/7,4/5,4/3,4一周期解并蕴含浑沌的一个条件。 相似文献
55.
伪狂犬病毒闽A株基因文库的构建及物理图谱分析 总被引:6,自引:0,他引:6
本文报道以质粒pBR322作载体,用鸟枪法克隆出了PRV闽A株除BamHI-1,2外的所有酶切片段,构建了PRV闽A株基因文库,并以克隆出的BamHI片段用光生物素标记作探针,应用分子杂交法确定了PRV闽A株绝大部分限制性内切酶位点的位置。 相似文献
56.
Corine Vernet Joëlle Boretto Marie-Geneviève Mattéi Masahide Takahashi Lucinda J. W. Jack Ian H. Mather Sylvie Rouquier Pierre Pontarotti 《Journal of molecular evolution》1993,37(6):600-612
Summary During a search for novel coding sequences within the human MHC class I region (chromosome 6p21.3), we found an exon (named B30-2) coding for a 166-amino-acid peptide which is very similar to the C-terminal domain of several coding sequences: human 52-kD Sjögren's syndrome nuclear antigen A/Ro (SS-A/Ro) and ret finger protein (RFP), Xenopus nuclear factor 7 (XNF7), and bovine butyrophilin. The first three of these proteins share similarities over the whole length of the molecule whereas butyrophilin is similar in the C-terminal domain. The N-terminal domain of butyrophilin is similar to rat myelin/oligodendrocyte glycoprotein (MOG) and chicken B blood group system (B-G) protein. These domains are components of a new subfamily of the immunoglobulin superfamily (IgSF). Butyrophilin is thus a mosaic protein composed of the MOG/B-G Ig-like domain and the C-terminal domain of 52-kD SS-A/Ro, RFP, and XNF7 (1330-2-like domain). Moreover, in situ hybridization shows that RFP, butyrophilin, and MOG map to the human chromosome 6p2l.3-6p22 region and are thus close to the MHC class I genes. It is therefore possible that the butyrophilin gene is the product of an exon shuffling event which occurred between ancestors of the RFP and MOG genes. To our knowledge, this is the first example of the colocalization of a chimeric gene and its putative progenitors. Finally, regulatory protein T-lymphocyte 1 (Rpt-1) shares similarities with the N-terminal halves of RFP, 52-kD SS-A/Ro, and XNF7, but not with the B30-2-like domain. We show that the ancestral Rpt-l gene evolved by overprinting.
Correspondence to: P. Pontarotti 相似文献
57.
Mapping of genes controlling seed storage-proteins and cytological markers on chromosome 1R of rye 总被引:1,自引:0,他引:1
J. Orellana B. Fernández-Calvín J. F. Vázquez J. M. Carrillo 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1993,85(5):639-643
Summary Rye secalins, telomeric C-bands, and telocentric chromosomes were used as markers in the progeny of a test-cross in order to determine the position of seed storage-protein genes Glu-R1 and Gli-R1 with respect to the centromere and both telomeres of chromosome 1 R in rye. These genes were linked to the centromere (32.35±3.28% and 36.27±3.37% recombination, respectively). Glu-R1 was loosely linked to the telomere of the long arm (43.63±3.47% recombination), while Gli-R1 was closely linked to the telomere of the short arm (9.80±2.08% recombination). This finding supports the possibility that rye - and -secalin genes may be located on the satellites, as has been described in wheat for genes that code similar proteins. The importance of metaphase-I pairing failure and its consequences for the estimation of the recombination fraction are also discussed. 相似文献
58.
A panel of bovine somatic cell hybrids was used to map ovine microsatellites. Five of seven microsatellites were assigned to five bovine syntenic groups. These microsatellites were designated D5S10 (MAF23), D1S4 (MAF46), D13S1 (MAF18), D4S3 (MAF50), and DXS2 (MAF45), mapped to syntenic groups U3 (chromosome 5), U10 (chromosome 1), U11, U13, and the X chromosome, respectively. Two remaining sheep microsatellites amplified rodent DNA in the hybrid somatic cell panel, and were not assigned to bovine syntenic groups. Assignment of ovine-derived microsatellites to bovine syntenic groups provides additional evidence of the usefulness of microsatellites for mapping closely related species. The use of ovine and bovine microsatellites will aid in development of comparative genomic maps for these two species. 相似文献
59.
本文报道在我国广西隆林壮族中发现一个罕見的HbQ复合α,β地中海贫血家系。先证者女,18岁,贫血面容,肝脾肿大。化学结构分析确证本Hb变异体为HbQ Thailand[α74(EF3)Asp→His]。血红蛋白组成以及α和β珠蛋白基因分析结果表明,先证者的珠蛋白基因型为-α~Q/-α~T复合β°/β°(IVSI-1G→T/Codon17A→T);先证者父的基因型为-‘α~Q/-复合β~O/β~A(IVSI-1G→T/β~A);先证母的基因型为-α~T/αα复合β~O/β~A(Codon17A→T/β~A)。 相似文献
60.
Mapping of ben genes of Pseudomonas aeruginosa 总被引:1,自引:0,他引:1
Abstract Four ben genes responsible for the conversion of benzoate to catechol in Pseudomonas aeruginosa PAO have been mapped to a 4.6 kb Kpn I fragment. ben -1 and ben -4 were known to be separate genes but now ben-1508 has been found to be different from ben-2 . The two genes were distinguished by Tn 5 mutagenesis of a cosmid clone and deletion mapping. It is likely that the four genes mapped ( ben-4, ben-2, ben-1508 and ben-1 ) correspond to the previously characterized benR (regulatory gene) and benABC (benzoate dioxygenase) respectively. 相似文献