全文获取类型
收费全文 | 1522篇 |
免费 | 133篇 |
国内免费 | 1篇 |
出版年
2023年 | 4篇 |
2022年 | 5篇 |
2021年 | 23篇 |
2020年 | 19篇 |
2019年 | 31篇 |
2018年 | 18篇 |
2017年 | 33篇 |
2016年 | 48篇 |
2015年 | 73篇 |
2014年 | 89篇 |
2013年 | 104篇 |
2012年 | 131篇 |
2011年 | 126篇 |
2010年 | 80篇 |
2009年 | 68篇 |
2008年 | 92篇 |
2007年 | 73篇 |
2006年 | 83篇 |
2005年 | 74篇 |
2004年 | 72篇 |
2003年 | 72篇 |
2002年 | 58篇 |
2001年 | 23篇 |
2000年 | 22篇 |
1999年 | 18篇 |
1998年 | 11篇 |
1997年 | 9篇 |
1996年 | 7篇 |
1995年 | 11篇 |
1994年 | 5篇 |
1993年 | 10篇 |
1992年 | 15篇 |
1991年 | 11篇 |
1990年 | 20篇 |
1989年 | 21篇 |
1988年 | 7篇 |
1987年 | 13篇 |
1986年 | 8篇 |
1985年 | 5篇 |
1984年 | 4篇 |
1983年 | 7篇 |
1981年 | 4篇 |
1980年 | 3篇 |
1979年 | 4篇 |
1977年 | 5篇 |
1976年 | 9篇 |
1975年 | 4篇 |
1974年 | 7篇 |
1973年 | 5篇 |
1968年 | 5篇 |
排序方式: 共有1656条查询结果,搜索用时 15 毫秒
1.
Daniele Caligiore Magda Mustile Daniele Cipriani Peter Redgrave Jochen Triesch Maria De Marsico Gianluca Baldassarre 《PloS one》2015,10(3)
Intrinsic motivations drive the acquisition of knowledge and skills on the basis of novel or surprising stimuli or the pleasure to learn new skills. In so doing, they are different from extrinsic motivations that are mainly linked to drives that promote survival and reproduction. Intrinsic motivations have been implicitly exploited in several psychological experiments but, due to the lack of proper paradigms, they are rarely a direct subject of investigation. This article investigates how different intrinsic motivation mechanisms can support the learning of visual skills, such as “foveate a particular object in space”, using a gaze contingency paradigm. In the experiment participants could freely foveate objects shown in a computer screen. Foveating each of two “button” pictures caused different effects: one caused the appearance of a simple image (blue rectangle) in unexpected positions, while the other evoked the appearance of an always-novel picture (objects or animals). The experiment studied how two possible intrinsic motivation mechanisms might guide learning to foveate one or the other button picture. One mechanism is based on the sudden, surprising appearance of a familiar image at unpredicted locations, and a second one is based on the content novelty of the images. The results show the comparative effectiveness of the mechanism based on image novelty, whereas they do not support the operation of the mechanism based on the surprising location of the image appearance. Interestingly, these results were also obtained with participants that, according to a post experiment questionnaire, had not understood the functions of the different buttons suggesting that novelty-based intrinsic motivation mechanisms might operate even at an unconscious level. 相似文献
2.
Gabrielle C. Winters Gianluca Polese Anna Di Cosmo Leonid L. Moroz 《Journal of morphology》2020,281(7):790-801
Neuropeptide Y (NPY) is an evolutionarily conserved neurosecretory molecule implicated in a diverse complement of functions across taxa and in regulating feeding behavior and reproductive maturation in Octopus. However, little is known about the precise molecular circuitry of NPY-mediated behaviors and physiological processes, which likely involve a complex interaction of multiple signal molecules in specific brain regions. Here, we examined the expression of NPY throughout the Octopus central nervous system. The sequence analysis of Octopus NPY precursor confirmed the presence of both, signal peptide and putative active peptides, which are highly conserved across bilaterians. In situ hybridization revealed distinct expression of NPY in specialized compartments, including potential “integration centers,” where visual, tactile, and other behavioral circuitries converge. These centers integrating separate circuits may maintain and modulate learning and memory or other behaviors not yet attributed to NPY-dependent modulation in Octopus. Extrasomatic localization of NPY mRNA in the neurites of specific neuron populations in the brain suggests a potential demand for immediate translation at synapses and a crucial temporal role for NPY in these cell populations. We also documented the presence of NPY mRNA in a small cell population in the olfactory lobe, which is a component of the Octopus feeding and reproductive control centers. However, the molecular mapping of NPY expression only partially overlapped with that produced by immunohistochemistry in previous studies. Our study provides a precise molecular map of NPY mRNA expression that can be used to design and test future hypotheses about molecular signaling in various Octopus behaviors. 相似文献
3.
Sonia Coni Silvia Maria Serrao Zuleyha Nihan Yurtsever Laura Di Magno Rosa Bordone Camilla Bertani Valerio Licursi Zaira Ianniello Paola Infante Marta Moretti Marialaura Petroni Francesca Guerrieri Alessandro Fatica Alberto Macone Enrico De Smaele Lucia Di Marcotullio Giuseppe Giannini Marella Maroder Enzo Agostinelli Gianluca Canettieri 《Cell death & disease》2020,11(12)
4.
5.
Hanhan Liu Qiangqiang Jia Gianluca Tettamanti Sheng Li 《Insect biochemistry and molecular biology》2013,43(11):1068-1078
In the fruitfly, Drosophila melanogaster, autophagy and caspase activity function in parallel in the salivary gland during metamorphosis and in a common regulatory hierarchy during oogenesis. Both autophagy and caspase activity progressively increase in the remodeling fat body, and they are induced by a pulse of the molting hormone (20-hydroxyecdysone, 20E) during the larval-prepupal transition. Inhibition of autophagy and/or caspase activity in the remodeling fat body results in 25–40% pupal lethality, depending on the genotypes. Interestingly, a balancing crosstalk occurs between autophagy and caspase activity in this tissue: the inhibition of autophagy induces caspase activity and the inhibition of caspases induces autophagy. The Drosophila remodeling fat body provides an in vivo model for understanding the molecular mechanism of the balancing crosstalk between autophagy and caspase activity, which oppose with each other and are induced by the common stimulus 20E, and blockage of either path reinforces the other path. 相似文献
6.
W Taccone M Gion F Pecchio M Rapellino C Tremolada R Mione C Gatti A Ruol A Segalin M Dei Poli 《The International journal of biological markers》1991,6(3):173-176
An ELISA method for the determination of circulating specific HSV-TAA antibodies has recently become available (TAF test). The presence of TAF was tested in serum of 154 patients with primary esophageal carcinoma, collected in three institutions. The overall TAF-test positivity rate was 57.1%, being significantly lower in stage IV than in stage III patients. The concordance rate between TAF and CEA, ferritin, TPA, SCC and TATI was low, suggesting that TAF is probably independent of the other tumor markers evaluated. The clinical role of TAF-test determination in patients with esophageal carcinoma is currently under evaluation. 相似文献
7.
8.
L Morpurgo I Savini G Gatti M Bolognesi L Avigliano 《Biochemical and biophysical research communications》1988,152(2):623-628
A very pure ascorbate oxidase solution was obtained by dissolving a crystalline sample of the enzyme. The ratio between 280 and 610 nm absorbancies was 22.5. It contained 8.0 +/- 0.2 Cu ions, 50% EPR detectable, per dimeric molecule (140,000 M.W.) with a molar extinction coefficient of 10,000 cm-1 at 610 nm. Two Cu ions were removed by treatment with N,N-diethyldithiocarbamate. The optical blue absorption band was unaffected, while two EPR detectable Cu ions were lost, with disappearance of the type 2 Cu signal. It is concluded that native ascorbate oxidase contains two type 1, two type 2, and four type 3 Cu ions. 相似文献
9.
R L Walford T Gossett G M Troup R A Gatti K K Mittal A Robins G B Ferrara E Zeller 《Journal of immunology (Baltimore, Md. : 1950)》1976,116(6):1704-1710
An analysis of the typing results of a 70-member chronic lymphatic leukemia B cell panel revealed evidence for 13 possible groups of the Merrit alloantigenic system. Six of these appeared possibly allelic and may represent a segregant series. The CLL panel was also fully typed for HLA and some degree of linkage dysequilibrium between Merrit and HLA seemed apparent from the data. Merrit antibodies can be absorbed out with selected surface membrane immunoglobulin (SMIG)-positive normal lymphocytes and less so or not at all with E rosette-forming T cells or Fc-positive SMIG-negative lymphocytes. 相似文献
10.
Salar Shaaf Gianluca Bretani Abhisek Biswas Irene Maria Fontana Laura Rossini 《植物学报(英文版)》2019,61(3):226-256
In cereals, tillering and leaf development are key factors in the concept of crop ideotype, introduced in the 1960 s to enhance crop yield, via manipulation of plant architecture. In the present review, we discuss advances in genetic analysis of barley shoot architecture,focusing on tillering, leaf size and angle. We also discuss novel phenotyping techniques, such as 2 D and 3 D imaging, that have been introduced in the era of phenomics, facilitating reliable trait measurement. We discuss the identification of genes and pathways that are involved in barley tillering and leaf development,highlighting key hormones involved in the control of plant architecture in barley and rice. Knowledge on genetic control of traits related to plant architecture provides useful resources for designing ideotypes for enhanced barley yield and performance. 相似文献