全文获取类型
收费全文 | 372篇 |
免费 | 37篇 |
国内免费 | 1篇 |
出版年
2023年 | 2篇 |
2022年 | 4篇 |
2021年 | 5篇 |
2020年 | 2篇 |
2018年 | 7篇 |
2017年 | 8篇 |
2016年 | 8篇 |
2015年 | 8篇 |
2014年 | 10篇 |
2013年 | 11篇 |
2012年 | 18篇 |
2011年 | 20篇 |
2010年 | 20篇 |
2009年 | 22篇 |
2008年 | 16篇 |
2007年 | 19篇 |
2006年 | 27篇 |
2005年 | 14篇 |
2004年 | 19篇 |
2003年 | 19篇 |
2002年 | 23篇 |
2001年 | 16篇 |
2000年 | 16篇 |
1999年 | 10篇 |
1998年 | 7篇 |
1997年 | 8篇 |
1996年 | 5篇 |
1995年 | 5篇 |
1994年 | 4篇 |
1993年 | 2篇 |
1992年 | 4篇 |
1991年 | 4篇 |
1990年 | 4篇 |
1989年 | 2篇 |
1988年 | 2篇 |
1986年 | 4篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1982年 | 1篇 |
1981年 | 2篇 |
1980年 | 5篇 |
1979年 | 1篇 |
1977年 | 5篇 |
1975年 | 3篇 |
1974年 | 7篇 |
1972年 | 2篇 |
1971年 | 2篇 |
1969年 | 1篇 |
1968年 | 1篇 |
1967年 | 1篇 |
排序方式: 共有410条查询结果,搜索用时 15 毫秒
401.
402.
The differential effect of either one night's total sleep deprivation (TSD) or of selective REM deprivation (REMD) was examined on post-deprivation daytime EEG patterns with respect to control, in the same group of rhesus monkeys. TSD resulted in significantly decreased wakefulness and increased amounts of NREM and REM on the first day following TSD. In contrast, highly significant REM elevation without alteration of other EEG states occurred for 3 days after REMD. Post-deprivation behavioural and photic-induced neural changes were minor. The results obtained after sleep deprivation in simians are comparable with similar findings in human subjects. 相似文献
403.
K. R. Barker R. S. Hussey L. R. Krusberg G. W. Bird R. A. Dunn H. Ferris V. R. Ferris D. W. Freckman C. J. Gabriel P. S. Grewal A. E. MacGuidwin D. L. Riddle P. A. Roberts D. P. Schmitt 《Journal of nematology》1994,26(2):127-137
Plant and soil nematodes significandy impact our lives. Therefore, we must understand and manage these complex organisms so that we may continue to develop and sustain our food production systems, our natural resources, our environment, and our quality of life. This publication looks specifically at soil and plant nematology. First, the societal impact of nematodes and benefits of nematology research are briefly presented. Next, the opportunities facing nematology in the next decade are outlined, as well as the resources needed to address these priorities. The safety and sustainability of U.S. food and fiber production depends on public and administrative understanding of the importance of nematodes, the drastic effects of nematodes on many agricultural and horticultural crops, and the current research priorities of nematology. 相似文献
404.
Genetic engineering of rice (Oryza sativa L. cv. Pusa basmati 1) using synthetic Cry1Ac gene has been achieved by “particle bombardment”. Scutellar tissues excised after 5 – 6 d from mature seeds cultured on
induction medium were bombarded using gold particles coated with a mixture of Cry1Ac and marker genes on medium with osmoticum. Bombarded tissues were subjected to 30 mg dm−3 hygromycin selection for two cycles. The selected calli after GUS assay were transferred to shoot regeneration medium. Regenerated
shoots were rooted and plantlets (T0) were grown to full maturity. Polymerase chain reaction (PCR) analysis of T0 plants using Cry1Ac specific primers revealed the presence of Cry1Ac gene in 65 % plants. Phenotypic assay, β-glucuronidase assay and PCR during T1 generation revealed the inheritance of the Cry1Ac and marker genes along with the native plant genes. 相似文献
405.
Xian B. Mardiros Ronni Park Bryan Clifton Gurman Grewal Amina K. Khizar Therese A. Markow 《Fly》2016,10(4):162-171
Speciation can occur through the presence of reproductive isolation barriers that impede mating, restrict cross-fertilization, or render inviable/sterile hybrid progeny. The D. willistoni subgroup is ideally suited for studies of speciation, with examples of both allopatry and sympatry, a range of isolation barriers, and the availability of one species complete genome sequence to facilitate genetic studies of divergence. D. w. willistoni has the largest geographic distribution among members of the Drosophila willistoni subgroup, spanning from Argentina to the southern United States, including the Caribbean islands. A subspecies of D. w. willistoni, D. w. quechua, is geographically separated by the Andes mountain range and has evolved unidirectional sterility, in that only male offspring of D. w. quechua females × D. w. willistoni males are sterile. Whether D. w. willistoni flies residing east of the Andes belong to one or more D. willistoni subspecies remains unresolved. Here we perform fecundity assays and show that F1 hybrid males produced from crosses between different strains found in Central America, North America, and northern Caribbean islands are reproductively isolated from South American and southern Caribbean island strains as a result of unidirectional hybrid male sterility. Our results show the existence of a reproductive isolation barrier between the northern and southern strains and suggest a subdivision of the previously identified D. willistoni willistoni species into 2 new subspecies. 相似文献
406.
407.
408.
Background
Guanosine triphosphate (GTP)-binding proteins play an important role in regulation of G-protein. Thus prediction of GTP interacting residues in a protein is one of the major challenges in the field of the computational biology. In this study, an attempt has been made to develop a computational method for predicting GTP interacting residues in a protein with high accuracy (Acc), precision (Prec) and recall (Rc). 相似文献409.
410.
K.K. Grewal 《FEMS microbiology letters》1990,69(1-2):97-99
The normally silent 4.5 kb tellurite resistance transposon Tn521 of RP4 has been shown to carry sequences from both the flanking kilA and korA loci of this broad host range plasmid. The major portion of both of these sequences were used as probes to examine DNA homology in Southern transfer hybridization experiments with plasmid recipients of Tn521 chosen from varying incompatibility groups. In the case of every recipients molecule analyzed using either probe, DNA homology was observed. 相似文献