全文获取类型
收费全文 | 1168篇 |
免费 | 115篇 |
专业分类
1283篇 |
出版年
2023年 | 8篇 |
2022年 | 17篇 |
2021年 | 19篇 |
2020年 | 16篇 |
2019年 | 27篇 |
2018年 | 38篇 |
2017年 | 27篇 |
2016年 | 42篇 |
2015年 | 75篇 |
2014年 | 60篇 |
2013年 | 92篇 |
2012年 | 101篇 |
2011年 | 74篇 |
2010年 | 41篇 |
2009年 | 49篇 |
2008年 | 54篇 |
2007年 | 61篇 |
2006年 | 56篇 |
2005年 | 39篇 |
2004年 | 25篇 |
2003年 | 26篇 |
2002年 | 28篇 |
2001年 | 24篇 |
2000年 | 29篇 |
1999年 | 15篇 |
1998年 | 13篇 |
1997年 | 7篇 |
1995年 | 10篇 |
1993年 | 11篇 |
1992年 | 18篇 |
1991年 | 14篇 |
1990年 | 8篇 |
1989年 | 5篇 |
1988年 | 10篇 |
1987年 | 8篇 |
1986年 | 8篇 |
1985年 | 9篇 |
1984年 | 10篇 |
1983年 | 6篇 |
1982年 | 7篇 |
1981年 | 10篇 |
1980年 | 6篇 |
1979年 | 6篇 |
1978年 | 8篇 |
1977年 | 4篇 |
1973年 | 3篇 |
1972年 | 3篇 |
1970年 | 3篇 |
1966年 | 4篇 |
1961年 | 5篇 |
排序方式: 共有1283条查询结果,搜索用时 11 毫秒
61.
62.
Ramón Montes Margarita Bedmar Maria Sol Martin 《Applied psychophysiology and biofeedback》1993,18(2):67-77
The aim of the present study was to apply EMG biofeedback as an auxiliary to piano teaching techniques. We studied the changes in integrated electromyographic activity, using the abductor pollicis brevis functioning as an agonist during the teaching of identical selective movements of piano playing in two groups, one with EMG biofeedback and the other following traditional method of instruction. The analysis of variance revealed an increase in the peak amplitude and the relaxation rate values for the biofeedback group. These results have implications for the application of piano playing techniques and reveal EMG biofeedback as an aid in the teaching of thumb attack with the abductor pollicis brevis as agonist.We are grateful for the valuable assistance of Dr. Jaime Vila (Professor of Therapy and Behavioral Modification, Faculty of Psychology, Granada), the cooperation of students at the Juventudes Musicales Music School, Santa Fe and at the Victoria Eugenia Conservatoire, (Granada), the Statistical Analysis Centre of University of Filosofia y Letras de Granada; Professor Enrique Garcia Fernandez-Abasal (Complutense University) for the design of the interface and software. 相似文献
63.
J. Cairó M. Vidal A. Villaverde F. Valero F. J. Lafuente C. Solà 《Biotechnology Techniques》1991,5(5):389-392
Summary A novel method to analyze -galactosidase by Flow Injection Analysis is presented with a linear working range extended to at least 2150 U/mL, being the detection limit 25 U/mL with 55 samples per hour frecuency and a BSD of 0.954% versus 2.4% obtained by manual assay. The method was tested with optimal results with samples from Escherichia coli cultures producing -galactosidase. 相似文献
64.
Bae JS Cheong HS Kim JH Park BL Kim JH Park TJ Kim JY Pasaje CF Lee JS Park YJ Park M Park C Koh I Chung YJ Lee JY Shin HD 《PloS one》2011,6(4):e19091
Background
Unlike Caucasian populations, genetic factors contributing to the risk of type 2 diabetes mellitus (T2DM) are not well studied in Asian populations. In light of this, and the fact that copy number variation (CNV) is emerging as a new way to understand human genomic variation, the objective of this study was to identify type 2 diabetes–associated CNV in a Korean cohort.Methodology/Principal Findings
Using the Illumina HumanHap300 BeadChip (317,503 markers), genome-wide genotyping was performed to obtain signal and allelic intensities from 275 patients with type 2 diabetes mellitus (T2DM) and 496 nondiabetic subjects (Total n = 771). To increase the sensitivity of CNV identification, we incorporated multiple factors using PennCNV, a program that is based on the hidden Markov model (HMM). To assess the genetic effect of CNV on T2DM, a multivariate logistic regression model controlling for age and gender was used. We identified a total of 7,478 CNVs (average of 9.7 CNVs per individual) and 2,554 CNV regions (CNVRs; 164 common CNVRs for frequency>1%) in this study. Although we failed to demonstrate robust associations between CNVs and the risk of T2DM, our results revealed a putative association between several CNVRs including chr15:45994758–45999227 (P = 8.6E-04, Pcorr = 0.01) and the risk of T2DM. The identified CNVs in this study were validated using overlapping analysis with the Database of Genomic Variants (DGV; 71.7% overlap), and quantitative PCR (qPCR). The identified variations, which encompassed functional genes, were significantly enriched in the cellular part, in the membrane-bound organelle, in the development process, in cell communication, in signal transduction, and in biological regulation.Conclusion/Significance
We expect that the methods and findings in this study will contribute in particular to genome studies of Asian populations. 相似文献65.
Susana Sevilla-Espinosa Maricela Solórzano-Campo Ricardo Bello-Mendoza 《Biodegradation》2010,21(5):737-751
The use of anaerobic processes to treat low-strength wastewater has been increasing in recent years due to their favourable
performance-costs balance. For optimal results, it is necessary to identify reactor configurations that are best suited for
this kind of application. This paper reports on the comparative study carried out with two high-rate anaerobic reactor systems
with the objective of evaluating their performances when used for the treatment of low-strength, complex wastewater. One of
the systems is the commonly used up-flow anaerobic sludge blanket (UASB) reactor. The other is the up-flow staged sludge bed
(USSB) system in which the reactor was divided longitudinally into 3, 5 and 7 compartments by the use of baffles. The reactors
(9 l) were fed with a synthetic, soluble and colloidal waste (chemical oxygen demand (COD) < 1000 mg/l) and operated at 28°C
and 24 h hydraulic retention time. Intermediate flow hydraulics, between plug-flow and completely-mixed, in the UASB and 7
stages USSB reactors allowed efficient degradation of substrates with minimum effluent concentrations. Low number of compartments
in the USSB reactors increased the levels of short-circuiting thus reducing substrate removal efficiencies. All reactors showed
high COD removal efficiencies (93–98%) and thus can be regarded as suitable for the treatment of low strength, complex wastewater.
Staged anaerobic reactors can be a good alternative for this kind of application provided they are fitted with a large enough
(≥7) number of compartments to fully take advantage of their strengths. Scale factors seem to have influenced importantly
on the comparison between one and multi staged sludge-bed reactors and, therefore, observations made here could change at
larger reactor volumes. 相似文献
66.
67.
Jarmila Solárová 《Biologia Plantarum》1970,12(2):110-116
Values of the water saturation deficit (WSD) for hydroactive stomatal movements of kale leaves were estimated using the method of transpiration curve analysis. Stomata of young leaves started closing at WSD values of 5 to 6 per cent and were completely closed at 18 to 20 per cent WSD. During maturation and ageing of leaves these WSD values increased to 12.5 and 18 to 23 per cent respectively. Thus the stomatal reaction is more sensitive to changes in WSD in adult leaves than in young ones. After maturation is attained both values decrease. In apparently withering leaves the individual phases of transpiration curves can barely be distinguished, probably for the reason that even under optimal conditions their stomata remain half-closed and at high WSD values an incomplete closing of the aperture occurs. The injured cuticle of withering leaves affects the shape of the transpiration curve as well. 相似文献
68.
69.
Andrés Solórzano Mónica Núñez-Flores Oscar Inostroza-Michael Cristián E. Hernández 《Palaeontology》2020,63(3):415-429
Species diversity patterns are governed by complex interactions among biotic and abiotic factors over time and space, but are essentially the result of the diversification dynamics (differential speciation and extinction rates) over the long-term evolutionary history of a clade. Previous studies have suggested that temporal variation in global temperature drove long-term diversity changes in Crocodylia, a monophyletic group of large ectothermic organisms. We use a large database of crocodylian fossil occurrences (192 spp.) and body mass estimations, under a taxic approach, to characterize the global diversification dynamics of crocodylians since the Cretaceous, and their correlation with multiple biotic and abiotic factors in a Bayesian framework. The diversification dynamic of crocodylians, which appears to have originated in the Turonian (c. 92.5 Ma), is characterized by several phases with high extinction and speciation rates within a predominantly low long-term mean rate. Our results reveal long-term diversification dynamics of Crocodylia to be a highly complex process driven by a combination of biotic and abiotic factors which influenced the speciation and extinction rates in dissimilar ways. Higher crocodylian extinction rates are related to low body mass disparity, indicating selective extinctions of taxa at both ends of the body mass spectrum. Speciation rate slowdowns are noted when the diversity of the clade is high and the warm temperate climatic belt is reduced. Our finding supports the idea that temporal variations of body mass disparity, self-diversity, and the warm climate belt size provided more direct mechanistic explanations for crocodylian diversification than do proxies of global temperature. 相似文献
70.
Hernández-Ledesma Ana Laura Rodríguez-Méndez Adriana Jheny Gallardo-Vidal Lilia Susana García-Gasca Teresa Alatorre-Cruz Julia María García-Solís Pablo López Reyes Julián Solís-Saínz Juan Carlos 《Molecular biology reports》2020,47(12):9667-9676
Molecular Biology Reports - Although cognitive impairment (CI) is classically associated with aging, it has been proposed that neurological pathologies may increase the risk to suffer CI. Despite... 相似文献