全文获取类型
收费全文 | 1070篇 |
免费 | 54篇 |
国内免费 | 54篇 |
出版年
2023年 | 13篇 |
2022年 | 9篇 |
2021年 | 32篇 |
2020年 | 18篇 |
2019年 | 26篇 |
2018年 | 28篇 |
2017年 | 18篇 |
2016年 | 16篇 |
2015年 | 36篇 |
2014年 | 48篇 |
2013年 | 64篇 |
2012年 | 48篇 |
2011年 | 48篇 |
2010年 | 29篇 |
2009年 | 48篇 |
2008年 | 56篇 |
2007年 | 51篇 |
2006年 | 54篇 |
2005年 | 51篇 |
2004年 | 46篇 |
2003年 | 47篇 |
2002年 | 41篇 |
2001年 | 40篇 |
2000年 | 24篇 |
1999年 | 27篇 |
1998年 | 25篇 |
1997年 | 23篇 |
1996年 | 17篇 |
1995年 | 22篇 |
1994年 | 16篇 |
1993年 | 20篇 |
1992年 | 15篇 |
1991年 | 22篇 |
1990年 | 13篇 |
1989年 | 9篇 |
1988年 | 10篇 |
1987年 | 12篇 |
1986年 | 6篇 |
1985年 | 8篇 |
1984年 | 4篇 |
1983年 | 5篇 |
1982年 | 7篇 |
1981年 | 6篇 |
1980年 | 3篇 |
1979年 | 6篇 |
1978年 | 3篇 |
1977年 | 1篇 |
1976年 | 3篇 |
1974年 | 2篇 |
1972年 | 1篇 |
排序方式: 共有1178条查询结果,搜索用时 15 毫秒
71.
Among domesticated mammals, rabbit (Oryctolagus cuniculus) is the only species possessing not more than one subclass of immunoglobulin (IgG) antibodies. The rabbit IGHGCH2 or e locus presents two serologically defined alleles, the e14 and e15 allotypes, which are correlated with amino acid variation at the IgG CH2-CH3 interface. Genetic studies, while revealing the adaptive value of this polymorphism, have relied so far entirely upon allo-antisera. Here we show how these alleles can be distinguished by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) methods. The proposed PCR-RFLP approach allows the monitoring of IGHG locus diversity in rabbit. 相似文献
72.
Svitashev SK Pawlowski WP Makarevitch I Plank DW Somers DA 《The Plant journal : for cell and molecular biology》2002,32(4):433-445
To more fully characterize the internal structure of transgene loci and to gain further understanding of mechanisms of transgene locus formation, we sequenced more than 160 kb of complex transgene loci in two unrelated transgenic oat (Avena sativa L.) lines transformed using microprojectile bombardment. The transgene locus sequences from both lines exhibited extreme scrambling of non-contiguous transgene and genomic fragments recombined via illegitimate recombination. A perfect direct repeat of the delivered DNA, and inverted and imperfect direct repeats were detected in the same transgene locus indicating that homologous recombination and synthesis-dependent mechanism(s), respectively, were also involved in transgene locus rearrangement. The most unexpected result was the small size of the fragments of delivered and genomic DNA incorporated into the transgene loci via illegitimate recombination; 50 of the 82 delivered DNA fragments were shorter than 200 bp. Eleven transgene and genomic fragments were shorter than the DNA lengths required for Ku-mediated non-homologous end joining. Detection of these small fragments provided evidence that illegitimate recombination was most likely mediated by a synthesis-dependent strand-annealing mechanism that resulted in transgene scrambling. Taken together, these results indicate that transgene locus formation involves the concerted action of several DNA break-repair mechanisms. 相似文献
73.
Transgenic Research - 相似文献
74.
Toward positional cloning of Vgt1, a QTL controlling the transition from the vegetative to the reproductive phase in maize 总被引:1,自引:0,他引:1
Salvi S Tuberosa R Chiapparino E Maccaferri M Veillet S van Beuningen L Isaac P Edwards K Phillips RL 《Plant molecular biology》2002,48(5-6):601-613
Vgt1 (Vegetative to generative transition 1) is a quantitative trait locus (QTL) for flowering time in maize (Zea mays L.). Vgt1 was initially mapped in a ca. 5-cM interval on chromosome bin 8.05, using a set of near-isogenic lines (NILs) in the genetic background of the late dent line N28, with the earliness allele introgressed from the early variety Gaspé Flint. A new large mapping population was produced by crossing N28 and one early NIL with a ca. 6-cM long Gaspé Flint introgression at the Vgt1 region. Using PCR-based assays at markers flanking Vgt1, 69 segmental NILs homozygous for independent crossovers near the QTL were developed. When the NILs were tested in replicated field trials for days to pollen shed (DPS) and plant node number (ND), the QTL followed a Mendelian segregation. Using bulk segregant analysis and AFLP profiling, 17 AFLP markers linked to the QTL region were identified. Statistical analysis indicated a substantial coincidence of the effects of Vgt1 on both DPS and ND. Vgt1 was mapped at ca. 0.3 cM from an AFLP marker. As compared to DPS, the higher heritability of ND allowed for a more accurate assessment of the effects of Vgt1. The feasibility of the positional cloning of Vgt1 is discussed. 相似文献
75.
Kobayashi S Fukuta Y Sato T Osaki M Khush GS 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2003,107(8):1350-1356
Rice (Oryza sativa L.) plants develop vertically with shoot elongation and horizontally with tillering. The purpose of this study was to identify and characterize genomic regions influencing the rice plant architecture by quantitative trait locus (QTL) analysis for the component traits: culm length (CL), panicle length (PnL), panicle number (PnN) and tiller number (TN). For this QTL analysis, 191 recombinant inbred lines (F7) derived from a cross of Milyang 23 (M23) and Akihikari (AK) were grown in 1995, 1996 and 1997 (May–Oct) in Joetsu, Japan (temperate climate), and in the 2000 dry season (Jan–Apr), the 2000 wet season (Jun–Oct) and the 2001 dry season in Los Baños, The Philippines (tropical climate). Results showed that rice plant architecture was influenced by 19 genomic regions categorized into five groups. In Group I, two regions (on chrs. 6 and 11) affected shoot elongation (CL and PnL) and tillering (PnN and TN) in opposite directions more significantly in Los Baños than in Joetsu. In Group II, two regions (chrs. 3 and 12) affected shoot elongation, whereas in Group III, five regions [chrs. 1 (two), 2, 3 and 9] affected only culm length (CL). Expressions of four regions of Group III were influenced by either tropical or temperate environments. In Group IV, seven regions (chrs. 1, 2, 4, 5, 6, 8 and 9) controlled panicle development (PnN or PnL), and in Group V, three regions (chrs. 1, 2 and 3) regulated tillering (PnN or TN). Characterizing these 19 genomic regions provided a detailed analysis of rice plant architecture with emphasis on the multiple effect and environmental responsive regions.Communicated by D. Mackill 相似文献
76.
Pleiotropic effect of a locus on chromosome 4 influencing alcohol drinking and emotional reactivity in rats 总被引:2,自引:0,他引:2
A QTL search in a segregating F2 intercross between HEP (High-Ethanol Preferring line) and wistar-kyoto (WKY, a low-alcohol consuming strain) rats identified a locus on chromosome 4 linked to the consumption of a 5% alcohol solution offered as a free choice with water (Terenina-Rigaldie et al. submitted). In order to confirm and analyse the influence of this locus, F2 rats were selected according to their genotype at the markers flanking the QTL and bred in order to obtain two groups of rats homozygous HEP/HEP ('HIGH' line) or WKY/WKY ('LOW' line) at the QTL, the rest of the genome being randomly inherited from one or the other founder strain. These two groups of animals displayed large differences in emotional reactivity (open field, elevated-plus maze), sensitivity to taste reinforcers (saccharin, quinine) and alcohol consumption (either forced or as a free choice with water). These results confirm the influence of this locus on alcohol intake and emotional reactivity traits, and suggest a pleiotropic effect of the gene(s) involved. Current research aims at the identification of this (these) gene(s). 相似文献
77.
Galea E Heneka MT Dello Russo C Feinstein DL 《Cellular and molecular neurobiology》2003,23(4-5):625-635
It is now well accepted that inflammatory responses in brain contribute to the genesis and evolution of damage in neurological diseases, trauma, and infection. Inflammatory mediators including cytokines, cell adhesion molecules, and reactive oxygen species including NO are detected in human brain and its animal models, and interventions that reduce levels or expression of these agents provide therapeutic benefit in many cases. Although in some cases, the causes of central inflammatory responses are clear—for example those due to viral infection in AIDS dementia, or those due to the secretion of proinflammatory substances by activated lymphocytes in multiple sclerosis—in other conditions the factors that allow the initiation of brain inflammation are not well understood; nor is it well known why brain inflammatory activation is not as well restricted as it is in the periphery. The concept is emerging that perturbation of endogenous regulatory mechanisms could be an important factor for initiation, maintenance, and lack of resolution of brain inflammation. Conversely, activation of intrinsic regulatory neuronal pathways could provide protection in neuroinflammatory conditions. This concept is the extension of the principle of central neurogenic neuroprotection formulated by Donald Reis and colleagues, which contends the existence of neuronal circuits that protect the brain against the damage initiated by excitotoxic injury. In this paper we will review work initiated in the Reis laboratory establishing that activation of endogenous neural circuits can exert anti-inflammatory actions in brain, present data suggesting that these effects could be mediated by noradrenaline, and summarize recent studies suggesting that loss of noradrenergic locus ceruleus neurons contributes to inflammatory activation in Alzheimer's disease. 相似文献
78.
Urvater JA McAdam SN Loehrke JH Allen TM Moran JL Rowell TJ Rojo S López de Castro JA Taurog JD Watkins DI 《Immunogenetics》2000,51(4-5):314-325
The human major histocompatibility complex (MHC) class I gene, HLA-B27, is a strong risk factor for susceptibility to a group of disorders termed spondyloarthropathies. Rodents that express HLA-B27 develop spondyloarthropathies, implicating HLA-B27 in the etiology of these disorders. To determine whether an HLA-B27-like molecule was associated with spondyloarthropathies
in nonhuman primates, we analyzed the MHC class I cDNAs expressed in a cohort of rhesus macaques that developed reactive arthritis
after an outbreak of shigellosis. We identified several cDNAs with only limited sequence similarity to HLA-B27. Interestingly, one of these MHC molecules had a B pocket identical to that of HLA-B39. Pool sequencing of radiolabeled peptides
bound by this molecule demonstrated that, like HLA-B27 and HLA-B39, it could bind peptides with arginine at the second position.
However, extensive analysis of the MHC class I molecules in this cohort revealed no statistically significant association
between any particular MHC class I allele and susceptibility to reactive arthritis. Furthermore, none of the rhesus MHC class I
molecules bore a strong resemblance to HLA-B27, indicating that reactive arthritis can develop in this animal model in the
absence of an HLA-B27-like molecule. Surprisingly, there was a statistically significant association between the rhesus macaque
MHC A locus allele, Mamu-A*12, and the absence of reactive arthritis following Shigella infection.
Received: 26 July 1999 / Revised: 28 December 1999 相似文献
79.
The classical view of norepinephrine transporter (NET) function is the re-uptake of released norepinephrine (NE) by mature sympathetic neurons and noradrenergic neurons of the locus ceruleus (LC; [1-3]). In this report we review previous data and present new results that show that NET is expressed in the young embryo in a wide range of neuronal and non-neuronal tissues and that NET has additional functions during embryonic development. Sympathetic neurons are derived from neural crest stem cells. Fibroblast growth factor-2 (FGF-2), neurotrophin-3 (NT-3) and transforming growth factor-1 (TGF-1) regulate NET expression in cultured quail neural crest cells by causing an increase in NET mRNA levels. They also promote NET function in both neural crest cells and presumptive noradrenergic cells of the LC. The growth factors are synthesized by the neural crest cells and therefore are likely to have autocrine function. In a subsequent stage of development, NE transport regulates differentiation of noradrenergic neurons in the peripheral nervous system and the LC by promoting expression of tyrosine hydroxylase (TH) and dopamine--hydroxylase (DBH). Conversely, uptake inhibitors, such as the tricyclic antidepressant, desipramine, and the drug of abuse, cocaine, inhibit noradrenergic differentiation in both tissues. Taken together, our data indicate that NET is expressed early in embryonic development, NE transport is involved in regulating expression of the noradrenergic phenotype in the peripheral and central nervous systems, and norepinephrine uptake inhibitors can disturb noradrenergic cell differentiation in the sympathetic ganglion (SG) and LC. 相似文献
80.