全文获取类型
收费全文 | 1360篇 |
免费 | 148篇 |
国内免费 | 1篇 |
出版年
2023年 | 5篇 |
2022年 | 19篇 |
2021年 | 39篇 |
2020年 | 28篇 |
2019年 | 32篇 |
2018年 | 47篇 |
2017年 | 24篇 |
2016年 | 61篇 |
2015年 | 79篇 |
2014年 | 77篇 |
2013年 | 93篇 |
2012年 | 123篇 |
2011年 | 101篇 |
2010年 | 59篇 |
2009年 | 71篇 |
2008年 | 63篇 |
2007年 | 73篇 |
2006年 | 62篇 |
2005年 | 49篇 |
2004年 | 46篇 |
2003年 | 47篇 |
2002年 | 36篇 |
2001年 | 34篇 |
2000年 | 28篇 |
1999年 | 20篇 |
1998年 | 17篇 |
1997年 | 8篇 |
1996年 | 16篇 |
1995年 | 8篇 |
1994年 | 15篇 |
1993年 | 8篇 |
1992年 | 16篇 |
1991年 | 11篇 |
1990年 | 8篇 |
1989年 | 7篇 |
1988年 | 13篇 |
1987年 | 7篇 |
1986年 | 11篇 |
1985年 | 8篇 |
1984年 | 7篇 |
1983年 | 4篇 |
1982年 | 8篇 |
1981年 | 3篇 |
1980年 | 7篇 |
1979年 | 2篇 |
1978年 | 2篇 |
1968年 | 1篇 |
1962年 | 1篇 |
1960年 | 1篇 |
1957年 | 1篇 |
排序方式: 共有1509条查询结果,搜索用时 15 毫秒
141.
142.
Michael Seyffert Daniel L. Glauser Kurt Tobler Oleg Georgiev Rebecca Vogel Bernd Vogt Leticia Agúndez Michael Linden Hildegard Büning Mathias Ackermann Cornel Fraefel 《Journal of virology》2015,89(21):11150-11158
Adeno-associated virus type 2 is known to inhibit replication of herpes simplex virus 1 (HSV-1). This activity has been linked to the helicase- and DNA-binding domains of the Rep68/Rep78 proteins. Here, we show that Rep68 can bind to consensus Rep-binding sites on the HSV-1 genome and that the Rep helicase activity can inhibit replication of any DNA if binding is facilitated. Therefore, we hypothesize that inhibition of HSV-1 replication involves direct binding of Rep68/Rep78 to the HSV-1 genome. 相似文献
143.
144.
Deanna M Church Valerie A Schneider Karyn Meltz Steinberg Michael C Schatz Aaron R Quinlan Chen-Shan Chin Paul A Kitts Bronwen Aken Gabor T Marth Michael M Hoffman Javier Herrero M Lisandra Zepeda Mendoza Richard Durbin Paul Flicek 《Genome biology》2015,16(1)
The human genome reference assembly is crucial for aligning and analyzing sequence data, and for genome annotation, among other roles. However, the models and analysis assumptions that underlie the current assembly need revising to fully represent human sequence diversity. Improved analysis tools and updated data reporting formats are also required. 相似文献
145.
Merino-Puerto V Schwarz H Maldener I Mariscal V Mullineaux CW Herrero A Flores E 《Molecular microbiology》2011,82(1):87-98
The filamentous, heterocyst‐forming cyanobacteria are multicellular organisms in which two different cell types, the CO2‐fixing vegetative cells and the N2‐fixing heterocysts, exchange nutrients and regulators. In Anabaena sp. strain PCC 7120, inactivation of sepJ or genes in the fraC operon (fraC, fraD and fraE) produce filament fragmentation. SepJ, FraC and FraD are cytoplasmic membrane proteins located in the filament's intercellular septa that are needed for intercellular exchange of the fluorescent tracer calcein (622 Da). Transmission electron microscopy showed an alteration in the heterocyst cytoplasmic membrane at the vegetative cell‐heterocyst septa in ΔfraC and ΔfraD mutants. Immunogold labelling of FraD confirmed its localization in the intercellular septa and clearly showed the presence of part of the protein between the cytoplasmic membranes of the adjacent cells. This localization seemed to be affected in the ΔfraC mutant but was not impaired in a ΔsepJ mutant. Intercellular transfer of a smaller fluorescent tracer, 5‐carboxyfluorescein (374 Da), was largely impaired in ΔfraC, ΔfraD and double ΔfraC‐ΔfraD mutants, but much less in the ΔsepJ mutant. These results show the existence in the Anabaena filaments of a FraC/FraD‐dependent intercellular molecular exchange that does not require SepJ. 相似文献
146.
147.
Coll TA Tito LP Sobarzo CM Cebral E 《Birth defects research. Part B, Developmental and reproductive toxicology》2011,92(6):560-574
The aim was to study the control females (CF)-1 mouse embryo differentiation, growth, morphology on embryonic E- and N-cadherin expression at midgestation after periconceptional moderate alcohol ingestion. Adult female mice were exposed to 10% ethanol in drinking water for 17 days previous to and up to day 10 of gestation (ethanol-exposed females, EF) and were compared with nonexposed CF. EF presented reduced quantities of E10 to E10.5 embryos, greater percentage of embryos at stages less than E7.5, reduced implantation site numbers/female, and increased resorptions compared with CF. EF-embryo growth was significantly affected as evidenced by reduced cephalic and body sizes of E10 and E10.5 embryos (scanning electron microscopy) and decreased protein content of E10.5 embryos vs. CF embryos. A significantly higher percentage of EF-E10-10.5 embryos presented abnormal neural tube (NT) closure vs. the percentage of CF. E10 embryos from EF presented elevated tissue disorganization, pyknosis and nuclear condensation in somites, mesenchymal and neuroepithelial tissue. Immunohistochemical E- and N-cadherin distribution patterns were similar in organic structures of E10 embryos between groups. However, western blot revealed that E- and N-cadherin expression levels were significantly increased in EF-derived embryos vs. controls. Perigestational ethanol consumption by CF-1 mice induced significant damage in the organogenic embryogenesis by producing delayed differentiation, growth deficiencies, and increasing the frequency of NT defects. Ethanol exposure may disrupt cell-cell adhesion leading to upregulation of E- and N-cadherin expression suggesting that deregulation of cell adhesion molecules could be involved in the disruption of embryo development at organogenesis in CF-1 mouse. 相似文献
148.
Blanco Juan Carlos Ballesteros Fernando Garca-Serrano Alicia Herrero Juan Nores Carlos Palomero Guillermo 《European Journal of Wildlife Research》2011,57(3):669-673
Although brown bears (Ursus arctos) are known to be major predators of ungulates in North America and Northern Europe, there is little documentation regarding
bear predation on wild ungulates in Southern Europe. We describe search, detection, killing and prey consumption behaviour
by brown bears during seven attacks on <1-month roe deer, red deer and chamois fawns in spring in the Cantabrian Mountains,
north-western Spain. As soon as the bears detected a fawn by their smell or their mother's presence, they switched from routine
foraging on plants and insects to an intensive search for the fawns, mainly using smell to comb a 0.5–1 ha area for 15–45 min.
They killed the fawns either while the latter were resting or after a brief chase. The bears usually took their prey to dense
vegetation, consuming it immediately. In four cases, 5-month-old cubs accompanying the female did not participate in the hunt.
We also document the apparently non-predatory killing of a 40-kg wild boar by a female bear with cubs surprised by a sudden
encounter. They did not eat the boar after the attack. 相似文献
149.
Bianca BZ Vigna Guilherme C Alleoni Leticia Jungmann Cacilda B do Valle Anete P de Souza 《BMC research notes》2011,4(1):523
Background
Urochloa humidicola is a forage grass that grows in tropical regions and is recognized for its tolerance to seasonal flooding. It is a polyploid and apomictic species with high phenotypic plasticity. As molecular tools are important in facilitating the development of new cultivars and in the classification of related species, the objectives of this study were to develop new polymorphic microsatellite markers from an enriched library constructed from U. humidicola and to evaluate their transferability to other Urochloa species.Findings
Microsatellite sequences were identified from a previously constructed enriched library, and specific primers were designed for 40 loci. Isolated di-nucleotide repeat motifs were the most abundant followed by tetra-nucleotide repeats. Of the tested loci, 38 displayed polymorphism when screened across 34 polyploid Urochloa sp. genotypes, including 20 accessions and six hybrids of U. humidicola and two accessions each from U. brizantha, U. dictyoneura, U. decumbens and U. ruziziensis. The number of bands per Simple Sequence Repeat (SSR) locus ranged from one to 29 with a mean of 11.5 bands per locus. The mean Polymorphism Information Content (PIC) of all loci was 0.7136, and the mean Discrimination Power (DP) was 0.7873. Six loci amplified in all species tested. STRUCTURE analysis revealed six different allelic pools, and the genetic similarity values analyzed using Jaccard's coefficient ranged from 0.000 to 0.913.Conclusions
This work reports new polymorphic microsatellite markers that will be useful for breeding programs for Urochloa humidicola and other Urochloa species as well as for genetic map development, germplasm characterization, evolutionary and taxonomic studies and marker-assisted trait selection.150.
Increasing germplasm erosion requires the recovery and conservation of traditional cultivars before they disappear. Here we present a particular case in Spain where a thorough prospection of local fruit tree species was performed in the 1950s with detailed data of the origin of each genotype but, unfortunately, the accessions are no longer conserved in ex situ germplasm collections. However, for most of those cultivars, an old stone collection is still preserved. In order to analyze the diversity present at the time when the prospection was made and to which extent variability has been eroded, we developed a protocol in apricot (Prunus armeniaca L.) to obtain DNA from maternal tissues of the stones of a sufficient quality to be amplified by PCR. The results obtained have been compared with the results from the profiles developed from apricot cultivars currently conserved in ex situ germplasm collections. The results highlight the fact that most of the old accessions are not conserved ex situ but provide a tool to prioritize the recovery of particular cultivars. The approach used in this work can also be applied to other plant species where seeds have been preserved. 相似文献