全文获取类型
收费全文 | 424884篇 |
免费 | 47812篇 |
国内免费 | 163篇 |
专业分类
472859篇 |
出版年
2018年 | 3903篇 |
2016年 | 5287篇 |
2015年 | 6902篇 |
2014年 | 8148篇 |
2013年 | 11233篇 |
2012年 | 12796篇 |
2011年 | 13242篇 |
2010年 | 9079篇 |
2009年 | 8434篇 |
2008年 | 12119篇 |
2007年 | 12614篇 |
2006年 | 11832篇 |
2005年 | 11307篇 |
2004年 | 11357篇 |
2003年 | 10638篇 |
2002年 | 10457篇 |
2001年 | 17420篇 |
2000年 | 17428篇 |
1999年 | 13910篇 |
1998年 | 5020篇 |
1997年 | 5269篇 |
1996年 | 4910篇 |
1995年 | 4617篇 |
1994年 | 4483篇 |
1993年 | 4536篇 |
1992年 | 11606篇 |
1991年 | 11534篇 |
1990年 | 11292篇 |
1989年 | 10906篇 |
1988年 | 10486篇 |
1987年 | 10075篇 |
1986年 | 9362篇 |
1985年 | 9231篇 |
1984年 | 7746篇 |
1983年 | 6702篇 |
1982年 | 5160篇 |
1981年 | 4616篇 |
1980年 | 4462篇 |
1979年 | 7419篇 |
1978年 | 5863篇 |
1977年 | 5396篇 |
1976年 | 5201篇 |
1975年 | 5594篇 |
1974年 | 6300篇 |
1973年 | 6166篇 |
1972年 | 5764篇 |
1971年 | 5226篇 |
1970年 | 4633篇 |
1969年 | 4574篇 |
1968年 | 4421篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
941.
Rita Padányi Yuning Xiong Géza Antalffy Krisztina Lór Katalin Pászty Emanuel E. Strehler ágnes Enyedi 《The Journal of biological chemistry》2010,285(41):31704-31712
The membrane localization of the plasma membrane Ca2+-ATPase isoform 2 (PMCA2) in polarized cells is determined by alternative splicing; the PMCA2w/b splice variant shows apical localization, whereas the PMCA2z/b and PMCA2x/b variants are mostly basolateral. We previously reported that PMCA2b interacts with the PDZ protein Na+/H+ exchanger regulatory factor 2 (NHERF2), but the role of this interaction for the specific membrane localization of PMCA2 is not known. Here we show that co-expression of NHERF2 greatly enhanced the apical localization of GFP-tagged PMCA2w/b in polarized Madin-Darby canine kidney cells. GFP-PMCA2z/b was also redirected to the apical membrane by NHERF2, whereas GFP-PMCA2x/b remained exclusively basolateral. In the presence of NHERF2, GFP-PMCA2w/b co-localized with the actin-binding protein ezrin even after disruption of the actin cytoskeleton by cytochalasin D or latrunculin B. Surface biotinylation and fluorescence recovery after photobleaching experiments demonstrated that NHERF2-mediated anchorage to the actin cytoskeleton reduced internalization and lateral mobility of the pump. Our results show that the specific interaction with NHERF2 enhances the apical concentration of PMCA2w/b by anchoring the pump to the apical membrane cytoskeleton. The data also suggest that the x/b splice form of PMCA2 contains a dominant lateral targeting signal, whereas the targeting and localization of the z/b form are more flexible and not fully determined by intrinsic sequence features. 相似文献
942.
S. M. Pershin E. Sh. Ismailov Z. G. Suleimanova Z. N. Abdulmagomedova D. Z. Zagirova 《Biophysics》2014,59(2):334-338
It has been experimentally established that cultivation of yeast cells in depleted, dietary or normal nutrient aqueous solutions enriched with ortho-H2O spin isomers is accompanied by an increase in the amount of carbon dioxide produced by the cells and an increase in their biomass. It has been revealed that the rate of metabolic processes and biological activity depends on the quality of nutrition and enhances in time in both nutrient solutions. In contrast, the reproductive function and the rate of cell division are insusceptible to the components of nutrition, but intensified in a solution enriched with ortho-H2O similar to retardation of aging. The observed effects are discussed in assumption that an increase of a portion of ortho-H2O molecules occurs in the neighborhood of water channels in the cell membrane that let through only monomers of H2O and determine the rate vicinity of metabolic processes. 相似文献
943.
Riccardo E. Marioni Lars Penke Gail Davies Jennifer E. Huffman Caroline Hayward Ian J. Deary 《Proceedings. Biological sciences / The Royal Society》2014,281(1781)
Human cognitive ability shows consistent, positive associations with fitness components across the life-course. Underlying genetic variation should therefore be depleted by selection, which is not observed. Genetic variation in general cognitive ability (intelligence) could be maintained by a mutation–selection balance, with rare variants contributing to its genetic architecture. This study examines the association between the total number of rare stop-gain/loss, splice and missense exonic variants and cognitive ability in childhood and old age in the same individuals. Exome array data were obtained in the Lothian Birth Cohorts of 1921 and 1936 (combined N = 1596). General cognitive ability was assessed at age 11 years and in late life (79 and 70 years, respectively) and was modelled against the total number of stop-gain/loss, splice, and missense exonic variants, with minor allele frequency less than or equal to 0.01, using linear regression adjusted for age and sex. In both cohorts and in both the childhood and late-life models, there were no significant associations between rare variant burden in the exome and cognitive ability that survived correction for multiple testing. Contrary to our a priori hypothesis, we observed no evidence for an association between the total number of rare exonic variants and either childhood cognitive ability or late-life cognitive ability. 相似文献
944.
In patients suffering from Parkinson's disease (PD), we analyzed correlations between the parameters of contingent negative
variation (CNV) and data of variational pulsometry (according to the measurements of R-R ECG intervals). Studies were carried
out on 35 patients (group PD), 49 to 74 years old, with the stage of disease of 1.5 to 3.0 according to the Hoehn-Yahr international
classification. In the course of CNV recording (i.e., in the state of a certain functional loading), we observed significant
negative correlations between the integral magnitude (area) of this potential and indices of variational pulsometry (RMSSD,
SDNN, C. var, and HF) that characterize the intensity of parasympathetic (respiratory) influences on the cardiovascular system.
In the control group, such correlations were absent. We found significant correlations between the autonomic balance, CNV
magnitude, and stage of PD reflecting the level of generalization of the pathological process. In the subgroup of patients
with the PD stage 1.5 to 2.0, significant changes in the mean values of indices of parasympathetic influences during recording
of the CNV were not observed, while in another subgroup (the PD stage 2.5 to 3.0), these values increased significantly (P < 0.05 and P < 0.01). If the estimates of the PD stage were low, the CNV area demonstrated greater values (P < 0.01). The disturbance of coordination of muscle-to-muscle interactions in the PD group is, probably, an important factor
responsible for parasympathetic dysregulation and suppression of the CNV generation. We found positive correlation between
the intensity of parasympathetic influences in the course of CNV recording and the level of postural disorders (r = 0.37, P < 0.05). On the contrary, the CNV magnitude demonstrated a negative correlation with the intensity of these disorders (r = −0.36, P < 0.05), as well as with the level of postural instability (r = −0.55, P < 0.001). We hypothesize that alterations of the autonomic balance and the activity of those cerebral structures, which are
responsible for the motor readiness, result, to a significant extent, from weakening of the activity of the noradrenergic
system due to degenerative processes developing in cells of the locus coeruleus. The impairment of the latter structure, together with degeneration of neurons of the substantia nigra and a decrease in the level of nigro-striatal dopamine, underlies the pathomorphological pattern of PD.
Neirofiziologiya/Neurophysiology, Vol. 40, No. 3, pp. 242–253, May–June, 2008. 相似文献
945.
E. V. Esin 《Journal of Ichthyology》2009,49(9):777-785
Seinings of the lowland bed of a typical small river of Western Kamchatka demonstrated that of several methods for the census
of juveniles of salmonids (Salmonidae) the most accurate result in comparison with complete removal is obtained by three-fold
seining with calculation of abundance by the Zippin method. In comparison with a seine, a drive-in trap and electrofishing
possess a lower average catching efficiency and a higher selectivity. The average density of fish estimated by the results
of seining at the investigated stretch was 0.55–0.57 specimens/m2. 相似文献
946.
947.
948.
949.
950.