全文获取类型
收费全文 | 2687篇 |
免费 | 153篇 |
国内免费 | 323篇 |
出版年
2024年 | 12篇 |
2023年 | 53篇 |
2022年 | 55篇 |
2021年 | 107篇 |
2020年 | 87篇 |
2019年 | 102篇 |
2018年 | 83篇 |
2017年 | 84篇 |
2016年 | 82篇 |
2015年 | 90篇 |
2014年 | 109篇 |
2013年 | 164篇 |
2012年 | 89篇 |
2011年 | 91篇 |
2010年 | 86篇 |
2009年 | 111篇 |
2008年 | 117篇 |
2007年 | 136篇 |
2006年 | 135篇 |
2005年 | 129篇 |
2004年 | 117篇 |
2003年 | 111篇 |
2002年 | 78篇 |
2001年 | 99篇 |
2000年 | 91篇 |
1999年 | 79篇 |
1998年 | 81篇 |
1997年 | 69篇 |
1996年 | 73篇 |
1995年 | 63篇 |
1994年 | 61篇 |
1993年 | 57篇 |
1992年 | 35篇 |
1991年 | 28篇 |
1990年 | 21篇 |
1989年 | 18篇 |
1988年 | 14篇 |
1987年 | 21篇 |
1986年 | 14篇 |
1985年 | 25篇 |
1984年 | 22篇 |
1983年 | 13篇 |
1982年 | 15篇 |
1981年 | 11篇 |
1980年 | 6篇 |
1979年 | 6篇 |
1978年 | 6篇 |
1977年 | 2篇 |
1976年 | 2篇 |
1950年 | 1篇 |
排序方式: 共有3163条查询结果,搜索用时 15 毫秒
11.
Bruno W. S. Sobral Rhonda J. Honeycutt Alan G. Atherly Michael McClelland 《Plant Molecular Biology Reporter》1990,8(4):253-275
TheOryza sativa (rice) genome is small (600 to 900 megabase pairs) when compared to that of other monocotyledonous plants. Rice was the first
of the major cereals to be successfully transformed and regenerated. An RFLP map with approximately 300 markers is readily
available, and the DNA content per map unit is only two to three times that ofArabidopsis thaliana. Rice is also the main staple food for the majority of peoples in the world. We developed techniques for the preparation
of intact genomic DNA from Indica and Japonica subspecies of rice, used statistical methods to determine which restriction
endonucleases are rare-cutting, and used pulsed-field gel electrophoresis (PFE) to separate large fragments of rice DNA. Southern
hybridization to blotted rice PFE gels was used to show that the digests were complete. The long-term goal of our work is
to generate an integrated genetic/physical map for the rice genome, as well as helping to establish rice as a model for map-based
gene cloning and genome analysis. 相似文献
12.
猕猴属五个种mtDNA多态性研究 总被引:17,自引:2,他引:15
本文以10种限制性内切酶研究猕猴属5个种(Macaca mulatta.M.nemestrina.M.assemensis.M.thibetana,M arctoides)线粒体DNA进化。在13个个体中,共检出8种限制性类型。恒河猴种内存在广泛的线粒休DNA限制性片段长度多态性(RFLP)。结合日本猴(M.fuscata)的有关资料,构建了猕猴属6个种的分子系统树,并给出各个种的分化时间。结果表明,这6个种可分成4个类群,熊猴和藏酋猴、恒河猴和日本猴之间的遗传距离较近,可分别划为同一类群,红面猴与其他5种猴的遗传距离最远,在系统发生上分离最早。 相似文献
13.
Using DNA clones, the physical distance between the linked genesnov andstr inHaemophilus influenzae was estimated. Although none of the cloned inserts contained both the markers, pJ1-8StrR 13 (insert of 18·7 kb) includedstr gene at one end and part ofnov gene at the other end of the insert. By EcoRI restriction analysis and by Southern hybridization, the distance between the
two EcoRI sites, cutting at which inactivates the two genes, was estimated to be 17·7 kb. A single continuous EcoRI fragment
(containing 4EcoRI sites within it) carrying both the genes intact would need to be 20·4 kb in size. These estimates were confirmed independently
using different clones ofnov
r andstr
r alleles as probes for hybridization with BamHI-digested chromosomal DNA. 相似文献
14.
Mitochondrial DNA from the fall armyworm, Spodoptera frugiperda (J.E. Smith), was cloned and characterized using restriction enzyme mapping. Genome size is approximately 16.3 kilobase (Kb), consistent with that of most animals. Three fragments, 8.1 Kb, 6.2 Kb, and 2.0 Kb, were produced by digestion with restriction enzyme Xbal and cloned into a pUC19 vector. Twenty-nine restriction enzymes were used to generate a detailed physical restriction enzyme map of the three cloned fragments. These data represent the first detailed characterization of a lepidopteran mitochondrial genome. © 1992 Wiley-Liss, Inc. 相似文献
15.
David A. Patton Linda H. Franzmann David W. Meinke 《Molecular & general genetics : MGG》1991,227(3):337-347
Summary We have previously isolated and characterized over 90 recessive mutants of Arabidopsis thaliana defective in embryo development. These emb mutants have been shown to differ in lethal phase, extent of abnormal development, and response in culture. We demonstrate in this report the value and efficiency of mapping emb genes relative to visible and molecular markers. Sixteen genes essential for embryo development were mapped relative to visible markers by analyzing progeny of selfed F1 plants. Embryonic lethals are now the most common type of visible marker included on the linkage map of Arabidopsis. Backcrosses were used in several cases to orient genes relative to adjacent markers. Three genes were located to chromosome arms with telotrisomics by screening for a reduction in the percentage of aborted seeds produced by F1 plants. A restriction fragment length polymorphism (RFLP) mapping strategy that utilizes pooled EMB/EMB F2 plants was devised to increase the efficiency of mapping embryonic lethals relative to molecular markers. This strategy was tested by demonstrating that the biol locus of Arabidopsis is within 0.5 cM of an existing RFLP marker. Mapping embryonic lethals with both visible and molecular markers may therefore help to identify large numbers of genes with essential functions in Arabidopsis. 相似文献
16.
G. J. Muehlbauer P. E. Staswick J. E. Specht G. L. Graef R. C. Shoemaker P. Keim 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1991,81(2):189-198
Summary A molecular marker analysis of a near-isogenic line (NIL), its donor parent (DP), and its recurrent parent (RP) can provide information about linkages between molecular markers and a conventional marker introgressed into the NIL. If the DP and RP possess different alleles for a given molecular marker, and if the NIL possesses the same allele as the DP, then it is reasonable to presume a linkage between that molecular marker and the introgressed marker. In this study, we examined the utility of RFLPs as molecular markers for the NIL genemapping approach. The allelic status of fifteen RFLP loci was determined in 116 soybean RP/NIL/DP line sets; 66 of the Clark RP type and 50 of the Harosoy RP type. Of the 1740 possible allelic comparisons (116 NILs x 15 RFLP loci), 1638 were tested and 462 (33.9%) of those were informative (i.e., the RP and DP had different RFLP alleles). In 15 (3.2%) of these 462 cases the NIL possessed the DP-derived RFLP allele, leading to a presumption of linkage between the RFLP locus and the introgressed conventional marker locus. Two presumptive linkages, pK-3 — and pK-472 — Lf
i, were subsequently confirmed by cosegregation linkage analysis. Although not yet confirmed, two other associations, pk-7 ab and pK-229 — y
9 seemed to be plausible linkages, primarily because the pk-7 — ab association was detected in two independently derived NILs and both markers of the pK-229 — y
9 association were known to be linked to Pb. The data obtained in this investigation indicated that RFLP loci were useful molecular markers for the NIL gene-mapping technique.Published as Paper no. 9101, Journal Series, Nebraska Agric. Res. Div. Project no. 12-091. Research partially funded by a grant from the Nebraska Soybean Development, Utilization, and Marketing Board 相似文献
17.
18.
两种锦鸡和环颈雉线粒体DNA(mtDNA)的比较研究 总被引:15,自引:3,他引:12
本文以10种限制性内切酶分析雉科中环颈雉,红腹锦鸡和白腹锦鸡线粒体DNA(mtDNA)。雉属与锦鸡属之间的遗传距离P为0.076(0.067-0.085),红腹锦鸡与白腹锦鸡的P为0.012。推算雉属和锦鸡属的分化大约发生在3.8×10[6]年以前,红腹锦鸡与白腹锦鸡的分化大约在6×10[5]年以前。这些结果表明:1.在雉科系统发生中,雉属与锦鸡属是近缘的属;2.红腹锦鸡和白腹锦鸡的分化较晚,关系密切,可能只是两个亚种。 相似文献
19.
20.
The effect of lake restoration measures on the physical,chemical and phytoplankton variables of Lake Bled 总被引:2,自引:2,他引:0
Monthly changes of physical, chemical and biological variables due a combination of artificial inflow of clean water, removal of hypolimnetic water, and diversion of sewage were studied in Lake Bled from December 1980 to December 1982.During the winter period 1981/82 the species composition of the phytoplankton changed. New species replaced those observed in previous years. We conclude that the combined effect of these three lake restoration measures was responsible for the sudden disappearance ofOscillatoria rubescens D.C. A marked decrease in some nutrients and an increase in temperature and oxygen concentration also occurred. 相似文献