全文获取类型
收费全文 | 734篇 |
免费 | 77篇 |
出版年
2022年 | 4篇 |
2021年 | 14篇 |
2020年 | 5篇 |
2019年 | 11篇 |
2018年 | 7篇 |
2017年 | 10篇 |
2016年 | 21篇 |
2015年 | 26篇 |
2014年 | 33篇 |
2013年 | 52篇 |
2012年 | 69篇 |
2011年 | 37篇 |
2010年 | 44篇 |
2009年 | 30篇 |
2008年 | 46篇 |
2007年 | 60篇 |
2006年 | 45篇 |
2005年 | 39篇 |
2004年 | 34篇 |
2003年 | 37篇 |
2002年 | 44篇 |
2001年 | 10篇 |
2000年 | 3篇 |
1999年 | 15篇 |
1998年 | 5篇 |
1997年 | 12篇 |
1996年 | 8篇 |
1995年 | 6篇 |
1994年 | 8篇 |
1993年 | 4篇 |
1992年 | 7篇 |
1991年 | 10篇 |
1990年 | 5篇 |
1989年 | 3篇 |
1988年 | 2篇 |
1987年 | 4篇 |
1986年 | 2篇 |
1985年 | 2篇 |
1984年 | 3篇 |
1983年 | 3篇 |
1982年 | 4篇 |
1981年 | 2篇 |
1980年 | 4篇 |
1978年 | 2篇 |
1977年 | 4篇 |
1976年 | 2篇 |
1975年 | 2篇 |
1973年 | 3篇 |
1972年 | 4篇 |
1967年 | 1篇 |
排序方式: 共有811条查询结果,搜索用时 965 毫秒
151.
Enzymatic synthesis of two lacto-N-neohexaose-related Lewis x heptasaccharides and their separation by chromatography on 总被引:3,自引:2,他引:1
Natunen Jari; Niemel Ritva; Penttil` Leena; Seppo Antti; Ruohtula Terfai; Renkonen Ossi 《Glycobiology》1994,4(5):577-583
Radiolabelled lacto-N-neohexaosc was fucosylated with partiallypurified 相似文献
152.
High neutral metallocarboxypeptidase activity (EC 3.4.17) has earlier been detected in young seedlings of rice ( Oryza sativa L.) using benzyloxycarbonyl-L-phenylalanyl-L-alanine (Z-Phe-Ala) as substrate at pH 7. This finding was confirmed, and it was observed that the activity could be assayed with higher specificity and sensitivity by using Z-Gly-Ala or Z-Gly-Phe as substrate at pH 6.5–7. No corresponding activity was detected in seedlings of barley ( Hordeum vulgare L. cv. Himalaya), oats ( Avena sativa L.) or maize ( Zea mays L.). The seedlings of the four cereals possessed similar activities of acid carboxypeptidases (EC 3.4.16; hydrolysis of Z-Phe-Ala and Z-Ala-Phe at pH 5.2 and of Z-Ala-Arg at pH 5.7). However, in endosperms of germinating rice and maize these activities were only about 1–5% of those in barley and oats. A corresponding, although less pronounced, difference was evident between the scutella of the two pairs of cereals. The possible relationship between neutral carboxypeptidase activity and ability to grow in anaerobic conditions is discussed. 相似文献
153.
Summary Reserpine has a stimulatory effect on the pars intermedia of the rat pituitary, probably mediated by its action on regulatory catecholaminergic nerves. The effect of single intraperitoneal injections of 0.1–20 mg/kg b.w. of reserpine was studied in adult male rats. Reserpine at a dose of 2 mg/kg b.w. induced degranulation, orientation of the secretory granules along the cell membrane and loss of formaldehyde-chloral-induced fluorescence, accompanied by an activation of the granular endoplasmic reticulum and the Golgi apparatus. With higher doses progressive degranulation and loss of fluorescence were observed. The effect was, however, heterogeneous, and with all doses cells displaying normal ultrastructure and normal fluorescence were regularly present.To study the release of granular products (containing a different components of the pro-opiomelanocortin chain) from individual cells, formaldehyde-chloral induced fluorescence and -MSH- and -endorphin immunoreactivies were demonstrated in consecutive sections from pituitaries of rats given 8 mg/kg body weight of reserpine 24 h before sacrifice. The results indicate coordinated release of these granular products at the cellular level after reserpine treatment.This work was supported by Finska Läkaresällskapet 相似文献
154.
Maris Laan Kristiina Grön-Virta Armi Salo Pertti Aula Leena Peltonen Aarno Palotie Ann-Christine Syvänen 《Human genetics》1995,96(3):275-280
The solid-phase minisequencing method (Syvänen et al. 1990) allows accurate quantative determination of the ratio between two DNA or RNA sequences that are present as a mixture in a sample and differ from each other only by a single nucleotide. Here, we present another application of the minisequening method, the determination of the gene copy number in a genome. The copy number of a marker gene aspartyl glucosaminidase (AGA) located at 4qter, was determined in three patients with a chromosomal alteration involving the distal region of 4q. For the minisequencing assay an equal amount of DNA from a patient homozygous for a mutation in the AGA gene was added to the DNA samples concerned. The relative amount of the normal sequence determined in each combined sample gives the copy number of the AGA gene. Fluorescence in situ hybridization (FISH), applied in parallel as a control, produced concordant results with solid-phase minisequencing in each case. As the potential of the minisequencing lies in automation, it could be a useful tool in the screening of monosomies, trisomies or loss of heterozygosity in diagnostics. 相似文献
155.
Targeted Disruption of the Pemphigus Vulgaris Antigen (Desmoglein 3) Gene in Mice Causes Loss of Keratinocyte Cell Adhesion with a Phenotype Similar to Pemphigus Vulgaris 总被引:11,自引:0,他引:11
下载免费PDF全文
![点击此处可从《The Journal of cell biology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Peter J. Koch M G. Mahoney Hiroyasu Ishikawa Leena Pulkkinen Jouni Uitto Leonard Shultz George F. Murphy Diana Whitaker-Menezes John R. Stanley 《The Journal of cell biology》1997,137(5):1091-1102
In patients with pemphigus vulgaris (PV), autoantibodies against desmoglein 3 (Dsg3) cause loss of cell–cell adhesion of keratinocytes in the basal and immediate suprabasal layers of stratified squamous epithelia. The pathology, at least partially, may depend on protease release from keratinocytes, but might also result from antibodies interfering with an adhesion function of Dsg3. However, a direct role of desmogleins in cell adhesion has not been shown. To test whether Dsg3 mediates adhesion, we genetically engineered mice with a targeted disruption of the DSG3 gene. DSG3 −/− mice had no DSG3 mRNA by RNase protection assay and no Dsg3 protein by immunofluorescence (IF) and immunoblots. These mice were normal at birth, but by 8–10 d weighed less than DSG3 +/− or +/+ littermates, and at around day 18 were grossly runted. We speculated that oral lesions (typical in PV patients) might be inhibiting food intake, causing this runting. Indeed, oropharyngeal biopsies showed erosions with histology typical of PV, including suprabasilar acantholysis and “tombstoning” of basal cells. EM showed separation of desmosomes. Traumatized skin also had crusting and suprabasilar acantholysis. Runted mice showed hair loss at weaning. The runting and hair loss phenotype of DSG3 −/− mice is identical to that of a previously reported mouse mutant, balding (bal). Breeding indicated that bal is coallelic with the targeted mutation. We also showed that bal mice lack Dsg3 by IF, have typical PV oral lesions, and have a DSG3 gene mutation. These results demonstrate the critical importance of Dsg3 for adhesion in deep stratified squamous epithelia and suggest that pemphigus autoantibodies might interfere directly with such a function. 相似文献
156.
Satu Kuokkanen Michele Gschwend John D. Rioux Mark J. Daly Joseph D. Terwilliger Pentti J. Tienari Juhani Wikström Jorma Palo Lincoln D. Stein Thomas J. Hudson Eric S. Lander Leena Peltonen 《American journal of human genetics》1997,61(6):1379-1387
Multiple sclerosis (MS) is a neurological, demyelinating disorder with a putative autoimmune etiology. It is thought to be a multifactorial disease with a complex mode of inheritance. Here we report the results of a two-stage genomewide scan for loci predisposing to MS. The first stage of the screen, with a low-resolution map, was performed in a selection of 16 pedigrees collected from an isolated Finnish population. Multipoint, non-parametric linkage analysis of the 328 markers did not reveal statistically significant results. However, 10 slightly interesting regions (P = .1-.15) emerged, including our previous findings of the HLA complex on 6p21 and a putative locus on 5p14-p12. Eight of these novel regions were further analyzed by use of denser marker maps, in the second stage of the scan. For the chromosomal regions 4cen, 11tel, and 17q, the statistical significance increased, but not conclusively; for 2q32 and 10q21, the statistical significance did not change. Accordingly, genotyping of the high-density markers in these regions was performed, and the data were analyzed by use of two-point, parametric linkage analysis using the complete pedigree information of the 21 Finnish multiplex families. We detected suggestive evidence for a predisposing locus on chromosomal region 17q22-q24. Several markers on 17q22-q24 yielded positive LOD scores, with the maximum LOD score (Zmax) occurring with D17S807 (Zmax = 2.8, theta = .04; dominant model). Interestingly, a suggestive linkage between MS and the markers on 17q22-q24 was also revealed by a recent genomewide scan in MS families from the United Kingdom. 相似文献
157.
Laura Oksanen Miina Öhman Mark Heiman Katariina Kainulainen Jaakko Kaprio Pertti Mustajoki Veikko Koivisto Markku Koskenvuo Olli A. Jänne Leena Peltonen K. Kontula 《Human genetics》1997,99(5):559-564
Leptin, the product of the ob gene, reduces body fat in genetically obese animals and circulates in elevated concentrations in the blood of obese patients.
Polymorphic markers situated in the proximity of the human ob gene have recently been suggested to be linked to morbid obesity. We have studied the possible association between the microsatellite
markers near the ob gene and morbid obesity in 252 morbidly obese patients with a mean body mass index (BMI) of 43 ± 7 kg/m2, and 151 lean controls with a mean BMI of 22 ± 2 kg/m2, and searched for linkage of these gene markers to obesity in 76 affected sib-pairs (BMI ≥ 32). No significant association
was observed between any of the eight microsatellite markers and morbid obesity, and affected-sib-pair analysis failed to
show linkage of three selected ob gene markers to obesity in the sibships. There was a strong positive correlation between serum leptin levels and BMI in morbidly
obese patients; a carrier status for either of the two most prevalent alleles of the microsatellite marker D7S530 in the vicinity
of the ob gene was associated with serum leptin levels in the obese subjects. Two of the markers (D7S2519, D7S649) showed a significant
relation to the weight-losing response to a 16-week very-low-calorie dietary intervention. We have thus been able to confirm
a tight relationship between serum leptin and body mass but have found no evidence for genetic linkage of the ob gene markers to morbid obesity in a population considered to represent a genetic isolate and to be an ideal model for studies
of complex disorders.
Received: 25 October 1996 / Revised: 4 December 1996 相似文献
158.
159.
Shyamapada Nandi Santosh Kumar Singh Dinesh Mullangi Rajith Illathvalappil Leena George Chathakudath P. Vinod Sreekumar Kurungot Ramanathan Vaidhyanathan 《Liver Transplantation》2016,6(24)
Covalent organic frameworks (COFs) have structures and morphologies closely resembling graphenes, whose modular construction permits atomic‐level manipulations. This, combined with their porous structure, makes them excellent catalyst supports. Here, the high electrocatalytic activity of a composite, formed by supporting Ni3N nanoparticles on a benzimidazole COF, for oxygen evolution reaction is shown. The composite oxidizes alkaline water with a near‐record low overpotential of 230 mV @ 10 mA cm?2 (η 10). This high activity is attributed to the ability of the COF to confine the Ni3N nanoparticles to size regimes otherwise difficult to obtain and to its low band gap character (1.49 eV) arising from the synergy between the conducting Ni3N nanoparticles and the π‐conjugated COF. The COF itself, as a metal‐free self‐standing framework, has an oxygen evolution reaction activity with η 10 of 400 mV. The periodic structure of the COF makes it serve as a matrix to disperse the catalytically active Ni3N nanoparticles favoring their high accessibility and thereby good charge‐transport within the composite. This is evident from the amount of O2 evolved (230 mmol h?1 g?1), which, to the best of our knowledge, is the highest reported. The work reveals the emergence of COF as supports for electrocatalysts. 相似文献
160.
Young J. Kim Leena A. Ibrahim Sheng‐Zhi Wang Wei Yuan Oleg V. Evgrafov James A. Knowles Kai Wang Huizhong W. Tao Li I. Zhang 《Developmental neurobiology》2016,76(4):452-469
During the development of periphery auditory circuitry, spiral ganglion neurons (SGNs) form a spatially precise pattern of innervation of cochlear hair cells (HCs), which is an essential structural foundation for central auditory processing. However, molecular mechanisms underlying the developmental formation of this precise innervation pattern remain not well understood. Here, we specifically examined the involvement of Eph family members in cochlear development. By performing RNA‐sequencing for different types of cochlear cell, in situ hybridization, and immunohistochemistry, we found that EphA7 was strongly expressed in a large subset of SGNs. In EphA7 deletion mice, there was a reduction in the number of inner radial bundles originating from SGNs and projecting to HCs as well as in the number of ribbon synapses on inner hair cells (IHCs), as compared with wild‐type or heterozygous mutant mice, attributable to fewer type I afferent fibers. The overall activity of the auditory nerve in EphA7 deletion mice was also reduced, although there was no significant change in the hearing intensity threshold. In vitro analysis further suggested that the reduced innervation of HCs by SGNs could be attributed to a role of EphA7 in regulating outgrowth of SGN neurites as knocking down EphA7 in SGNs resulted in diminished SGN fibers. In addition, suppressing the activity of ERK1/2, a potential downstream target of EphA7 signaling, either with specific inhibitors in cultured explants or by knocking out Prkg1, also resulted in reduced SGN fibers. Together, our results suggest that EphA7 plays an important role in the developmental formation of cochlear innervation pattern through controlling SGN fiber ontogeny. Such regulation may contribute to the salience level of auditory signals presented to the central auditory system. © 2015 Wiley Periodicals, Inc. Develop Neurobiol 76: 452–469, 2016 相似文献