全文获取类型
收费全文 | 89篇 |
免费 | 0篇 |
专业分类
系统科学 | 2篇 |
理论与方法论 | 1篇 |
现状及发展 | 36篇 |
研究方法 | 20篇 |
综合类 | 30篇 |
出版年
2021年 | 1篇 |
2020年 | 1篇 |
2018年 | 1篇 |
2017年 | 2篇 |
2016年 | 1篇 |
2015年 | 1篇 |
2014年 | 3篇 |
2013年 | 2篇 |
2012年 | 10篇 |
2011年 | 7篇 |
2010年 | 3篇 |
2008年 | 6篇 |
2007年 | 6篇 |
2006年 | 5篇 |
2005年 | 3篇 |
2004年 | 5篇 |
2003年 | 2篇 |
2002年 | 7篇 |
2000年 | 1篇 |
1999年 | 1篇 |
1980年 | 3篇 |
1978年 | 1篇 |
1976年 | 1篇 |
1975年 | 2篇 |
1973年 | 1篇 |
1972年 | 1篇 |
1970年 | 1篇 |
1968年 | 2篇 |
1967年 | 3篇 |
1965年 | 1篇 |
1963年 | 1篇 |
1962年 | 1篇 |
1959年 | 1篇 |
1947年 | 1篇 |
1946年 | 1篇 |
排序方式: 共有89条查询结果,搜索用时 31 毫秒
61.
St. Arrenbrecht Elisabeth Hauschteck-Jungen H. Jungen 《Cellular and molecular life sciences : CMLS》1970,26(11):1279-1281
Summary The karyotype of 9Cepaea hortensis were analyzed. The haploid chromosome number was 22. 2 types of longest chromosomes were encountered. In 8 out of 9 animals, the longest chromosome had an arm ratio of 1.2. One animal showed a ratio of 4.9. This aberration is thought to have arisen by a pericentric inversion. Because both the normal and the aberrant chromosome coexisted in the same population, a chromosomal polymorphism seems to be present. 相似文献
62.
Nykjaer A Lee R Teng KK Jansen P Madsen P Nielsen MS Jacobsen C Kliemannel M Schwarz E Willnow TE Hempstead BL Petersen CM 《Nature》2004,427(6977):843-848
Sortilin (approximately 95 kDa) is a member of the recently discovered family of Vps10p-domain receptors, and is expressed in a variety of tissues, notably brain, spinal cord and muscle. It acts as a receptor for neurotensin, but predominates in regions of the nervous system that neither synthesize nor respond to this neuropeptide, suggesting that sortilin has additional roles. Sortilin is expressed during embryogenesis in areas where nerve growth factor (NGF) and its precursor, proNGF, have well-characterized effects. These neurotrophins can be released by neuronal tissues, and they regulate neuronal development through cell survival and cell death signalling. NGF regulates cell survival and cell death via binding to two different receptors, TrkA and p75NTR (ref. 10). In contrast, proNGF selectively induces apoptosis through p75NTR but not TrkA. However, not all p75NTR-expressing cells respond to proNGF, suggesting that additional membrane proteins are required for the induction of cell death. Here we report that proNGF creates a signalling complex by simultaneously binding to p75NTR and sortilin. Thus sortilin acts as a co-receptor and molecular switch governing the p75NTR-mediated pro-apoptotic signal induced by proNGF. 相似文献
63.
Aligianis IA Johnson CA Gissen P Chen D Hampshire D Hoffmann K Maina EN Morgan NV Tee L Morton J Ainsworth JR Horn D Rosser E Cole TR Stolte-Dijkstra I Fieggen K Clayton-Smith J Mégarbané A Shield JP Newbury-Ecob R Dobyns WB Graham JM Kjaer KW Warburg M Bond J Trembath RC Harris LW Takai Y Mundlos S Tannahill D Woods CG Maher ER 《Nature genetics》2005,37(3):221-223
Warburg Micro syndrome (WARBM1) is a severe autosomal recessive disorder characterized by developmental abnormalities of the eye and central nervous system and by microgenitalia. We identified homozygous inactivating mutations in RAB3GAP, encoding RAB3 GTPase activating protein, a key regulator of the Rab3 pathway implicated in exocytic release of neurotransmitters and hormones, in 12 families with Micro syndrome. We hypothesize that the underlying pathogenesis of Micro syndrome is a failure of exocytic release of ocular and neurodevelopmental trophic factors. 相似文献
64.
A first-generation linkage disequilibrium map of human chromosome 22 总被引:58,自引:0,他引:58
Dawson E Abecasis GR Bumpstead S Chen Y Hunt S Beare DM Pabial J Dibling T Tinsley E Kirby S Carter D Papaspyridonos M Livingstone S Ganske R Lõhmussaar E Zernant J Tõnisson N Remm M Mägi R Puurand T Vilo J Kurg A Rice K Deloukas P Mott R Metspalu A Bentley DR Cardon LR Dunham I 《Nature》2002,418(6897):544-548
DNA sequence variants in specific genes or regions of the human genome are responsible for a variety of phenotypes such as disease risk or variable drug response. These variants can be investigated directly, or through their non-random associations with neighbouring markers (called linkage disequilibrium (LD)). Here we report measurement of LD along the complete sequence of human chromosome 22. Duplicate genotyping and analysis of 1,504 markers in Centre d'Etude du Polymorphisme Humain (CEPH) reference families at a median spacing of 15 kilobases (kb) reveals a highly variable pattern of LD along the chromosome, in which extensive regions of nearly complete LD up to 804 kb in length are interspersed with regions of little or no detectable LD. The LD patterns are replicated in a panel of unrelated UK Caucasians. There is a strong correlation between high LD and low recombination frequency in the extant genetic map, suggesting that historical and contemporary recombination rates are similar. This study demonstrates the feasibility of developing genome-wide maps of LD. 相似文献
65.
66.
Remains of Homo erectus from Bouri, Middle Awash, Ethiopia 总被引:5,自引:0,他引:5
Asfaw B Gilbert WH Beyene Y Hart WK Renne PR WoldeGabriel G Vrba ES White TD 《Nature》2002,416(6878):317-320
The genesis, evolution and fate of Homo erectus have been explored palaeontologically since the taxon's recognition in the late nineteenth century. Current debate is focused on whether early representatives from Kenya and Georgia should be classified as a separate ancestral species ('H. ergaster'), and whether H. erectus was an exclusively Asian species lineage that went extinct. Lack of resolution of these issues has obscured the place of H. erectus in human evolution. A hominid calvaria and postcranial remains recently recovered from the Dakanihylo Member of the Bouri Formation, Middle Awash, Ethiopia, bear directly on these issues. These approximately 1.0-million-year (Myr)-old Pleistocene sediments contain abundant early Acheulean stone tools and a diverse vertebrate fauna that indicates a predominantly savannah environment. Here we report that the 'Daka' calvaria's metric and morphological attributes centre it firmly within H. erectus. Daka's resemblance to Asian counterparts indicates that the early African and Eurasian fossil hominids represent demes of a widespread palaeospecies. Daka's anatomical intermediacy between earlier and later African fossils provides evidence of evolutionary change. Its temporal and geographic position indicates that African H. erectus was the ancestor of Homo sapiens. 相似文献
67.
L. Hösli Elisabeth Hösli P. F. Andrès H. Landolt R. Renggli 《Cellular and molecular life sciences : CMLS》1980,36(12):1396-1396
Summary The depolarization of cultured astrocytes by GABA and glycine correlates in amplitude and time course with the increase of the extracellular K+-concentration during perfusion with these amino acids. It is suggested that the glial depolarization is caused by an efflux of K+ from neighbouring neurones activated by the amino acid transmitters. 相似文献
68.
Verpy E Weil D Leibovici M Goodyear RJ Hamard G Houdon C Lefèvre GM Hardelin JP Richardson GP Avan P Petit C 《Nature》2008,456(7219):255-258
Although the cochlea is an amplifier and a remarkably sensitive and finely tuned detector of sounds, it also produces conspicuous mechanical and electrical waveform distortions. These distortions reflect nonlinear mechanical interactions within the cochlea. By allowing one tone to suppress another (masking effect), they contribute to speech intelligibility. Tones can also combine to produce sounds with frequencies not present in the acoustic stimulus. These sounds compose the otoacoustic emissions that are extensively used to screen hearing in newborns. Because both cochlear amplification and distortion originate from the outer hair cells-one of the two types of sensory receptor cells-it has been speculated that they stem from a common mechanism. Here we show that the nonlinearity underlying cochlear waveform distortions relies on the presence of stereocilin, a protein defective in a recessive form of human deafness. Stereocilin was detected in association with horizontal top connectors, lateral links that join adjacent stereocilia within the outer hair cell's hair bundle. These links were absent in stereocilin-null mutant mice, which became progressively deaf. At the onset of hearing, however, their cochlear sensitivity and frequency tuning were almost normal, although masking was much reduced and both acoustic and electrical waveform distortions were completely lacking. From this unique functional situation, we conclude that the main source of cochlear waveform distortions is a deflection-dependent hair bundle stiffness resulting from constraints imposed by the horizontal top connectors, and not from the intrinsic nonlinear behaviour of the mechanoelectrical transducer channel. 相似文献
69.
We investigated the phase transformation sequence,kinetics,and microstructural evolutions during heating,isothermal treatment,and continuous cooling of the metastable Ti–B19 alloy.On the basis of these results,we summarized the phase transformation characteristics of this kind of alloys,especially the metastable b-Ti alloy.We also analyzed and discussed the possibility of describing the size,morphology,and distribution of precipitates as well as the possibility of and complications in establishing relationships among the chemical composition,microstructure,processing parameters,and properties of the metastable Ti–B19 alloy. 相似文献
70.
Martin Michaelis Christina Paulus Nadine Löschmann Stephanie Dauth Elisabeth Stange Hans Wilhelm Doerr Michael Nevels Jindrich CinatlJr. 《Cellular and molecular life sciences : CMLS》2011,68(6):1079-1090
Human cytomegalovirus (HCMV) is a major pathogen in immunocompromised individuals. Here, non-toxic concentrations of the anti-cancer
kinase inhibitor sorafenib were shown to inhibit replication of different HCMV strains (including a ganciclovir-resistant
strain) in different cell types. In contrast to established anti-HCMV drugs, sorafenib inhibited HCMV major immediate early
promoter activity and HCMV immediate early antigen (IEA) expression. Sorafenib is known to inhibit Raf. Comparison of sorafenib
with the MEK inhibitor U0126 suggested that sorafenib inhibits HCMV IEA expression through inhibition of Raf but independently
of signaling through the Raf downstream kinase MEK 1/2. In concordance, siRNA-mediated depletion of Raf but not of MEK-reduced
IEA expression. In conclusion, sorafenib diminished HCMV replication in clinically relevant concentrations and inhibited HCMV
IEA expression, a pathophysiologically relevant event that is not affected by established anti-HCMV drugs. Moreover, we demonstrated
for the first time that Raf activation is involved in HCMV IEA expression. 相似文献