全文获取类型
收费全文 | 3118篇 |
免费 | 250篇 |
国内免费 | 6篇 |
专业分类
3374篇 |
出版年
2022年 | 33篇 |
2021年 | 49篇 |
2020年 | 28篇 |
2019年 | 36篇 |
2018年 | 51篇 |
2017年 | 41篇 |
2016年 | 61篇 |
2015年 | 96篇 |
2014年 | 122篇 |
2013年 | 165篇 |
2012年 | 234篇 |
2011年 | 203篇 |
2010年 | 121篇 |
2009年 | 124篇 |
2008年 | 160篇 |
2007年 | 180篇 |
2006年 | 180篇 |
2005年 | 146篇 |
2004年 | 165篇 |
2003年 | 134篇 |
2002年 | 124篇 |
2001年 | 52篇 |
2000年 | 47篇 |
1999年 | 52篇 |
1998年 | 46篇 |
1997年 | 27篇 |
1996年 | 23篇 |
1995年 | 26篇 |
1994年 | 30篇 |
1993年 | 28篇 |
1992年 | 24篇 |
1991年 | 29篇 |
1990年 | 22篇 |
1989年 | 18篇 |
1988年 | 22篇 |
1987年 | 19篇 |
1986年 | 19篇 |
1985年 | 19篇 |
1984年 | 17篇 |
1983年 | 17篇 |
1982年 | 21篇 |
1980年 | 18篇 |
1979年 | 18篇 |
1978年 | 17篇 |
1977年 | 16篇 |
1974年 | 20篇 |
1973年 | 21篇 |
1971年 | 20篇 |
1970年 | 15篇 |
1967年 | 17篇 |
排序方式: 共有3374条查询结果,搜索用时 15 毫秒
81.
Chondronectin interactions with proteoglycan 总被引:1,自引:0,他引:1
H H Varner V J Horn G R Martin A T Hewitt 《Archives of biochemistry and biophysics》1986,244(2):824-830
We have investigated whether proteoglycans are involved in the attachment of embryonic chick chondrocytes to type II collagen. Chondroitin sulfate proteoglycan, when added exogenously, promotes the binding of chondronectin, the chondrocyte attachment factor, to type II collagen substrates and thereby stimulates chondrocyte adhesion. Blockage of endogenous proteoglycan synthesis with beta-xylosides prevents chondronectin-mediated chondrocyte attachment, confirming that proteoglycan is required. The intact proteoglycan must be present since chondroitin sulfate glycosaminoglycans did not promote chondronectin-mediated cell attachment but, rather, inhibited it in a dose-dependent manner. This inhibition, however, could be overcome with excess exogenous proteoglycan. Consequently, chondronectin interacts with proteoglycan and then the complex interacts with the collagen substrate and with the cell surface to promote cell adhesion. Further evidence for a direct interaction of chondronectin with the glycosaminoglycan portion of the proteoglycan is the selective binding of chondronectin to dextran-Sepharose, dextran having been shown to inhibit attachment to an extent similar to that of chondroitin sulfate. 相似文献
82.
Van Bergen NJ Crowston JG Kearns LS Staffieri SE Hewitt AW Cohn AC Mackey DA Trounce IA 《PloS one》2011,6(6):e21347
Autosomal Dominant Optic Atrophy (ADOA) is the most common inherited optic atrophy where vision impairment results from specific loss of retinal ganglion cells of the optic nerve. Around 60% of ADOA cases are linked to mutations in the OPA1 gene. OPA1 is a fission-fusion protein involved in mitochondrial inner membrane remodelling. ADOA presents with marked variation in clinical phenotype and varying degrees of vision loss, even among siblings carrying identical mutations in OPA1. To determine whether the degree of vision loss is associated with the level of mitochondrial impairment, we examined mitochondrial function in lymphoblast cell lines obtained from six large Australian OPA1-linked ADOA pedigrees. Comparing patients with severe vision loss (visual acuity [VA]<6/36) and patients with relatively preserved vision (VA>6/9) a clear defect in mitochondrial ATP synthesis and reduced respiration rates were observed in patients with poor vision. In addition, oxidative phosphorylation (OXPHOS) enzymology in ADOA patients with normal vision revealed increased complex II+III activity and levels of complex IV protein. These data suggest that OPA1 deficiency impairs OXPHOS efficiency, but compensation through increases in the distal complexes of the respiratory chain may preserve mitochondrial ATP production in patients who maintain normal vision. Identification of genetic variants that enable this response may provide novel therapeutic insights into OXPHOS compensation for preventing vision loss in optic neuropathies. 相似文献
83.
Wagner S Kufleitner J Zensi A Dadparvar M Wien S Bungert J Vogel T Worek F Kreuter J von Briesen H 《PloS one》2010,5(12):e14213
Background
Due to the use of organophosphates (OP) as pesticides and the availability of OP-type nerve agents, an effective medical treatment for OP poisonings is still a challenging problem. The acute toxicity of an OP poisoning is mainly due to the inhibition of acetylcholinesterase (AChE) in the peripheral and central nervous systems (CNS). This results in an increase in the synaptic concentration of the neurotransmitter acetylcholine, overstimulation of cholinergic receptors and disorder of numerous body functions up to death. The standard treatment of OP poisoning includes a combination of a muscarinic antagonist and an AChE reactivator (oxime). However, these oximes can not cross the blood-brain barrier (BBB) sufficiently. Therefore, new strategies are needed to transport oximes over the BBB.Methodology/Principal Findings
In this study, we combined different oximes (obidoxime dichloride and two different HI 6 salts, HI 6 dichloride monohydrate and HI 6 dimethanesulfonate) with human serum albumin nanoparticles and could show an oxime transport over an in vitro BBB model. In general, the nanoparticulate transported oximes achieved a better reactivation of OP-inhibited AChE than free oximes.Conclusions/Significance
With these nanoparticles, for the first time, a tool exists that could enable a transport of oximes over the BBB. This is very important for survival after severe OP intoxication. Therefore, these nanoparticulate formulations are promising formulations for the treatment of the peripheral and the CNS after OP poisoning. 相似文献84.
85.
86.
Judi E Hewitt Conrad A Pilditch 《Journal of experimental marine biology and ecology》2004,306(1):95-112
Epifaunal suspension-feeding bivalves can play important roles in marine ecosystems affecting macrobenthic communities, benthic boundary layers and benthic-pelagic coupling, not just by their presence but also by any changes in feeding behaviour. While seston quality and quantity have consistently been found to be important influences on the feeding rates of suspension-feeding bivalves, factors stressing individuals are also likely to be important, as they may affect energy-dependent thresholds of response. We postulated that (1) history of seston quantity would affect how suspension feeders deal with increases in total suspended particulates, and (2) high-seston concentrations would affect feeding rates more in individuals whose energy reserves were low after spawning. Three sites were selected for short-term (1 day) feeding experiments on the pinnid bivalve, Atrina zelandica. At one site, the experiment was run pre-and postspawning. Atrina exhibited high rejection of filtered particles (mostly 75% to 100%) and high organic absorption efficiencies (0.9-1) at all seston levels. Strong differences in the response of feeding behaviour to increased seston concentrations were observed between A. zelandica from the different sites, with lesser differences observed between times. The site-specific feeding responses to seston concentrations observed are likely to affect our ability to model responses of A. zelandica to sediment loading and to influence the importance of A. zelandica to benthic-pelagic coupling. 相似文献
87.
88.
89.
90.
de Sousa Sylvia Morais de Oliveira Christiane Abreu Andrade Daniele Luiz de Carvalho Chainheny Gomes Ribeiro Vitória Palhares Pastina Maria Marta Marriel Ivanildo Evódio de Paula Lana Ubiraci Gomes Gomes Eliane Aparecida 《Journal of Plant Growth Regulation》2021,40(2):867-877
Journal of Plant Growth Regulation - The rising demand for agricultural commodities in developing countries has put increasing pressure on land resources for higher yields, with associated growth... 相似文献