全文获取类型
收费全文 | 1154篇 |
免费 | 69篇 |
专业分类
1223篇 |
出版年
2024年 | 1篇 |
2023年 | 10篇 |
2022年 | 25篇 |
2021年 | 50篇 |
2020年 | 14篇 |
2019年 | 32篇 |
2018年 | 42篇 |
2017年 | 22篇 |
2016年 | 44篇 |
2015年 | 73篇 |
2014年 | 85篇 |
2013年 | 115篇 |
2012年 | 121篇 |
2011年 | 111篇 |
2010年 | 51篇 |
2009年 | 58篇 |
2008年 | 69篇 |
2007年 | 76篇 |
2006年 | 58篇 |
2005年 | 39篇 |
2004年 | 31篇 |
2003年 | 29篇 |
2002年 | 22篇 |
2001年 | 7篇 |
2000年 | 2篇 |
1999年 | 2篇 |
1998年 | 4篇 |
1997年 | 3篇 |
1996年 | 6篇 |
1995年 | 2篇 |
1994年 | 3篇 |
1993年 | 3篇 |
1992年 | 1篇 |
1989年 | 1篇 |
1988年 | 2篇 |
1987年 | 2篇 |
1985年 | 1篇 |
1983年 | 1篇 |
1980年 | 2篇 |
1976年 | 1篇 |
1973年 | 2篇 |
排序方式: 共有1223条查询结果,搜索用时 15 毫秒
191.
Enzo M. Vingolo Serena Salvatore Sonia Cavarretta 《Applied psychophysiology and biofeedback》2009,34(2):127-133
Macular disease is one of the main causes of visual impairment. We studied the efficacy of low-vision rehabilitation by means
of MP-1 biofeedback examination in patients with different macular disease. Five patients were enrolled (3 female and 2 male,
mean age 53.8 years) and a total of 9 eyes was examined: 2 eyes with vitelliform dystrophy, 1 with a post-traumatic macular
scar, 2 with Stargardt disease, 2 with myopic macular degeneration, 2 with cone dystrophy. All the patients underwent the
following tests: visual acuity, reading speed, fixation test, MP-1 microperimetry. Low-vision rehabilitation, which lasted
10 weeks, consisted of 10 training sessions of 10 min for each eye, performed once a week using the MP-1 biofeedback examination.
Statistical analysis was performed using Student’s t-test. p values less than 0.05 were considered statistically significant. After training all patients displayed an improvement in
visual acuity, fixation behaviour, retinal sensitivity and reading speed. Fixation behaviour within the 2° diameter circle
improved and was statistically significant for reading speed (p = 0.01). Reading speed improved from a mean value of 64.3 to 92 words/min. Our results show that audio feedback can, by increasing
attentional modulation, help the brain to fix the final preferred retinal locus. Audio feedback facilitates stimuli transmission
between intraretinal neurons as well as between the retina and brain, which is where the highest level of stimuli processing
occurs, thereby probably supporting a “remapping phenomenon”. 相似文献
192.
193.
Serena Santolamazza-Carbone Montserrat Pestaña Nieto Rosa Pérez Otero Pedro Mansilla Vázquez Adolfo Cordero Rivera 《BioControl》2009,54(2):195-209
We investigated the effects of temperature, photoperiod, food and host availability, and body size on the overwintering abilities
of the egg parasitoid Anaphes nitens Girault (Hymenoptera, Mymaridae) under natural conditions. Seven groups of eighty females received one of four treatments
(n = 20): (i) honey and hosts, (ii) water and hosts, (iii) honey, or (iv) water. Seven groups of forty males received only honey
or water (n = 20). To test if short day-length is the main cue for larval dormancy, the experiment was replicated inside a climate chamber
at 20°C and under a winter photoperiod. A. nitens overwinters because of quiescence or oligopause inside the hosts and increased adult longevity. Mean pre-emergence mortality
was up to 26% indoors and 15.2% outdoors, males being more affected. Development time had a significant and positive effect
on body size. Honey-fed females without hosts had the highest longevity (53 days). Mother’s diet and size affected development
time, body size, longevity, and fecundity of the progeny. The results confirm the good adaptation of the parasitoid to the
environmental conditions of NW Spain and its ability to synchronize its life cycle with the phenology of the host.
Handling editor: Drik Babendreier. 相似文献
194.
195.
Background
One of the most debated issues in the cognitive neuroscience of language is whether distinct semantic domains are differentially represented in the brain. Clinical studies described several anomic dissociations with no clear neuroanatomical correlate. Neuroimaging studies have shown that memory retrieval is more demanding for proper than common nouns in that the former are purely arbitrary referential expressions. In this study a semantic relatedness paradigm was devised to investigate neural processing of proper and common nouns.Methodology/Principal Findings
780 words (arranged in pairs of Italian nouns/adjectives and the first/last names of well known persons) were presented. Half pairs were semantically related (“Woody Allen” or “social security”), while the others were not (“Sigmund Parodi” or “judicial cream”). All items were balanced for length, frequency, familiarity and semantic relatedness. Participants were to decide about the semantic relatedness of the two items in a pair. RTs and N400 data suggest that the task was more demanding for common nouns. The LORETA neural generators for the related-unrelated contrast (for proper names) included the left fusiform gyrus, right medial temporal gyrus, limbic and parahippocampal regions, inferior parietal and inferior frontal areas, which are thought to be involved in the conjoined processing a familiar face with the relevant episodic information. Person name was more emotional and sensory vivid than common noun semantic access.Conclusions/Significance
When memory retrieval is not required, proper name access (conspecifics knowledge) is not more demanding. The neural generators of N400 to unrelated items (unknown persons and things) did not differ as a function of lexical class, thus suggesting that proper and common nouns are not treated differently as belonging to different grammatical classes. 相似文献196.
197.
198.
Rose G Romeo G Dato S Crocco P Bruni AC Hervonen A Majamaa K Sevini F Franceschi C Passarino G;GEnetics of Healthy Ageing Project Consortium 《PloS one》2010,5(10):e13395
Tissue specific somatic mutations occurring in the mtDNA control region have been proposed to provide a survival advantage. Data on twins and on relatives of long-lived subjects suggested that the occurrence/accumulation of these mutations may be genetically influenced. To further investigate control region somatic heteroplasmy in the elderly, we analyzed the segment surrounding the nt 150 position (previously reported as specific of Leukocytes) in various types of leukocytes obtained from 195 ultra-nonagenarians sib-pairs of Italian or Finnish origin collected in the frame of the GEHA Project. We found a significant correlation of the mtDNA control region heteroplasmy between sibs, confirming a genetic influence on this phenomenon. Furthermore, many subjects showed heteroplasmy due to mutations different from the C150T transition. In these cases heteroplasmy was correlated within sibpairs in Finnish and northern Italian samples, but not in southern Italians. This suggested that the genetic contribution to control region mutations may be population specific. Finally, we observed a possible correlation between heteroplasmy and Hand Grip strength, one of the best markers of physical performance and of mortality risk in the elderly. Our study provides new evidence on the relevance of mtDNA somatic mutations in aging and longevity and confirms that the occurrence of specific point mutations in the mtDNA control region may represent a strategy for the age-related remodelling of organismal functions. 相似文献
199.
Edward Bernard Robert P. Larkin Stellos Tavantzis M. Susan Erich Andrei Alyokhin Serena D. Gross 《Plant and Soil》2014,374(1-2):611-627
Aims
Integrating multiple soil and disease management practices may improve crop productivity and disease control, but potential interactions and limitations need to be determined.Methods
Three different potential disease-suppressive management practices, including a Brassica napus (rapeseed) green manure rotation crop, conifer-based compost amendment, and three biological control organisms (Trichoderma virens, Bacillus subtilis, and Rhizoctonia solani hypovirulent isolate Rhs1A1) were evaluated alone and in combination at sites with both organic and conventional management histories for their effects on soilborne diseases and tuber yield.Results
Rapeseed rotation reduced all observed soilborne diseases (stem canker, black scurf, common scab, and silver scurf) by 10 to 52 % in at least one year at both sites. Compost amendment had variable effects on tuber diseases, but consistently increased yield (by 9 to 15 %) at both sites. Biocontrol effects on disease varied, though Rhs1A1 decreased black scurf at the conventional site and T. virens reduced multiple diseases at the organic site in at least one year. Combining rapeseed rotation with compost amendment both reduced disease and increased yield, whereas biocontrol additions produced only marginal additive effects.Conclusions
Use of these treatments alone, and in combination, can be effective at reducing disease and increasing yield under both conventional and organic production practices. 相似文献200.
Gavazzo P Vella S Marchetti C Nizzari M Cancedda R Pagano A 《Journal of neurochemistry》2011,119(5):989-1001
Neuroblastoma is a pediatric cancer characterized by high malignancy and remarkable cell heterogeneity within the tumor nodules. It has been previously shown that the over-expression of a specific non-coding RNA, NDM29, reduces neuroblastoma development promoting cell differentiation. We have used neuroblastoma cells expressing NDM29 at its basal level (Mock cells) or at 5.4-fold higher levels (S1 cells) to investigate whether a functional differentiation correlates with morphological and biochemical development induced by NDM29 expression. First, analyzing the expression of specific markers we demonstrated that NDM29 expression is accompanied by a well coordinated differentiation process toward a neuron-like, rather than toward a glial-like, phenotype. Next, we defined the neuron-like traits of S1 in terms of secretion of cytokines involved in axon guidance, synapse formation and neurite outgrowth. Finally, we characterized the ionic channel apparatus of S1 cells by patch-clamp technique and compared with the Mock counterpart. S1 cells showed much higher levels of fast inactivating Na(+) current and were able to generate mature action potentials. Moreover, they developed expression of functional GABA(A) receptors on their membrane. In contrast, the two cell lines shared very similar pools of functional K(+) channels, although slight quantitative differences can be described. Our results suggest that a maturation occurs in neuroblastoma as a consequence of NDM29 expression, inducing the appearance of neuronal-like properties. In this context, S1 cells may represent a novel in vitro tool for electrophysiological and pharmacological studies of human cells of the neural lineage. 相似文献