全文获取类型
收费全文 | 4894篇 |
免费 | 334篇 |
专业分类
5228篇 |
出版年
2023年 | 22篇 |
2022年 | 57篇 |
2021年 | 101篇 |
2020年 | 52篇 |
2019年 | 86篇 |
2018年 | 95篇 |
2017年 | 90篇 |
2016年 | 128篇 |
2015年 | 197篇 |
2014年 | 229篇 |
2013年 | 332篇 |
2012年 | 444篇 |
2011年 | 386篇 |
2010年 | 245篇 |
2009年 | 200篇 |
2008年 | 334篇 |
2007年 | 307篇 |
2006年 | 305篇 |
2005年 | 259篇 |
2004年 | 259篇 |
2003年 | 243篇 |
2002年 | 179篇 |
2001年 | 63篇 |
2000年 | 50篇 |
1999年 | 53篇 |
1998年 | 58篇 |
1997年 | 42篇 |
1996年 | 51篇 |
1995年 | 34篇 |
1994年 | 26篇 |
1993年 | 24篇 |
1992年 | 32篇 |
1991年 | 33篇 |
1990年 | 21篇 |
1989年 | 19篇 |
1988年 | 12篇 |
1987年 | 7篇 |
1986年 | 12篇 |
1985年 | 14篇 |
1984年 | 16篇 |
1983年 | 13篇 |
1982年 | 19篇 |
1981年 | 11篇 |
1980年 | 9篇 |
1979年 | 9篇 |
1978年 | 10篇 |
1974年 | 5篇 |
1973年 | 4篇 |
1971年 | 4篇 |
1941年 | 4篇 |
排序方式: 共有5228条查询结果,搜索用时 15 毫秒
81.
82.
Bibiana S. O. Fam Guillermo Reales Pedro Vargas‐Pinilla Pamela Par Lucas H. Viscardi Vinicius A. Sortica Aline B. Felkl lvaro de O. Franco Aldo B. Lucion Claudio M. Costa‐Neto Alcides Pissinatti Francisco M. Salzano Vanessa R. Paixo‐Crtes Maria Ctira Bortolini 《American journal of primatology》2019,81(8)
Platyrrhini (New World monkeys, NWm) are a group of primates characterized by behavioral and reproductive traits that are otherwise uncommon among primates, including social monogamy, direct paternal care, and twin births. As a consequence, the study of Platyrrhine primates is an invaluable tool for the discovery of the genetic repertoire underlying these taxon‐specific traits. Recently, high conservation of vasopressin (AVP) sequence, in contrast with high variability of oxytocin (OXT), has been described in NWm. AVP and OXT functions are possible due to interaction with their receptors: AVPR1a, AVPR1b, AVPR2, and OXTR; and the variability in this system is associated with the traits mentioned above. Understanding the variability in the receptors is thus fundamental to understand the function and evolution of the system as a whole. Here we describe the variability of AVPR1b coding region in 20 NWm species, which is well‐known to influence behavioral traits such as aggression, anxiety, and stress control in placental mammals. Our results indicate that 4% of AVPR1b sites may be under positive selection and a significant number of sites under relaxed selective constraint. Considering the known role of AVPR1b, we suggest that some of the changes described here for the Platyrrhini may be a part of the genetic repertoire connected with the complex network of neuroendocrine mechanisms of AVP–OXT system in the modulation of the HPA axis. Thus, these changes may have promoted the emergence of social behaviors such as direct paternal care in socially monogamous species that are also characterized by small body size and twin births. 相似文献
83.
Cantalupo Claudio McCain Desiree Ward Jeannette P. 《International journal of primatology》2002,23(1):203-221
Head-cocking is rotation of the head about the rostrocaudal axis with a fixed direction of orientation. The behavior is a response to either visual or auditory stimuli according to species. Although head-cocking is prevalent in small primates, its functional significance is unclear. We studied head-cocking in response to a variety of novel visual and acoustic stimuli in Garnett's greater bush babies (Otolemur garnettii). We systematically varied stimulus type (animate vs. inanimate image) and mode of presentation (NON-VIDEO vs. VIDEO) to assess their effects on the head-cocking response. A higher incidence of head-cocking occurred with novel animal images and for NON-VIDEO presentations. Acoustic stimuli suppressed rather than facilitated head-cocking. Juveniles head-cocked much more than adults did. Clearly head-cocking in Otolemur garnettii is primarily involved in visual rather than auditory function. It does not serve simple sensory/perceptual functions such as depth perception or acuity. Instead, in consideration of the importance of novelty to the elicitation of the behavior, the higher incidence in younger animals, and the structure of the visual system, we propose that head-cocking is a motor strategy to encode the parameters of novel images in the process of form learning. 相似文献
84.
85.
86.
Sgt1 was described previously in yeast and humans to be a Hsp90 co‐chaperone and required for kinetochore assembly. We have identified a mutant allele of Sgt1 in Drosophila and characterized its function. Mutations in sgt1 do not affect overall kinetochore assembly or spindle assembly checkpoint. sgt1 mutant cells enter less frequently into mitosis and arrest in a prometaphase‐like state. Mutations in sgt1 severely compromise the organization and function of the mitotic apparatus. In these cells, centrioles replicate but centrosomes fail to mature, and pericentriolar material components do not localize normally resulting in highly abnormal spindles. Interestingly, a similar phenotype was described previously in Hsp90 mutant cells and correlated with a decrease in Polo protein levels. In sgt1 mutant neuroblasts, we also observe a decrease in overall levels of Polo. Overexpression of the kinase results in a substantial rescue of the centrosome defects; most cells form normal bipolar spindles and progress through mitosis normally. Taken together, these findings suggest that Sgt1 is involved in the stabilization of Polo allowing normal centrosome maturation, entry and progression though mitosis. 相似文献
87.
Claudio L. Messias Donald W. Roberts Anthony T. Grefig 《Journal of invertebrate pathology》1983,42(3):393-396
Six strains of the entomopathogenic fungus Matarhizium anisopliae var. anisopliae from North and South America and one strain of M. anisopliae var. major from Samoa were compared by pyrolysis-gas chromatography of conidia. Two strains established to be very similar by other methods proved 98% similar by pyrolysis-gas chromatography. Similarities of the other strains ranged from 62 to 88%. The method is proposed as a simple technique for routine identification of M. anisopliae strains. 相似文献
88.
Abstract Two Dematiaceous Hyphomycetes, Beltraniella lyrata and Beltraniopsis fabularis, found on tropical forest litter in the Tai National Park in Ivory Coast are proposed as new species and described. 相似文献
89.
Ferruccio Berti Claudio Omini Daniela Longiave 《Prostaglandins & other lipid mediators》1977,14(2):241-249
The horse-chestnut saponin Aescin, an anti-exudative compound, induces contraction of isolated portal vein of rat and rabbit. This effect appears to be mediated by Prostaglandins of Fα type.The ability of Aescin to stimulate generation and release of Prostaglandins has been demonstrated in isolated lung of the rat. Mass-fragmentographic analysis of the lung effluent indicate that when Aescin is perfused through this organ the release of PGF2α is increased. The capability of Aescin to generate Prostaglandins is discussed in connection with its anti-exudative activity. 相似文献
90.
Dean Frawley Claudio Greco Berl Oakley Mohamed M. Alhussain Alastair B. Fleming Nancy P. Keller
zgür Bayram 《Cellular microbiology》2020,22(6)
For eukaryotes like fungi to regulate biological responses to environmental stimuli, various signalling cascades are utilized, like the highly conserved mitogen‐activated protein kinase (MAPK) pathways. In the model fungus Aspergillus nidulans, a MAPK pathway known as the pheromone module regulates development and the production of secondary metabolites (SMs). This pathway consists five proteins, the three kinases SteC, MkkB and MpkB, the adaptor SteD and the scaffold HamE. In this study, homologs of these five pheromone module proteins have been identified in the plant and human pathogenic fungus Aspergillus flavus. We have shown that a tetrameric complex consisting of the three kinases and the SteD adaptor is assembled in this species. It was observed that this complex assembles in the cytoplasm and that MpkB translocates into the nucleus. Deletion of steC, mkkB, mpkB or steD results in abolishment of both asexual sporulation and sclerotia production. This complex is required for the positive regulation of aflatoxin production and negative regulation of various SMs, including leporin B and cyclopiazonic acid (CPA), likely via MpkB interactions in the nucleus. These data highlight the conservation of the pheromone module in Aspergillus species, signifying the importance of this pathway in regulating fungal development and secondary metabolism. 相似文献