全文获取类型
收费全文 | 361篇 |
免费 | 32篇 |
国内免费 | 1篇 |
出版年
2022年 | 2篇 |
2021年 | 5篇 |
2020年 | 2篇 |
2019年 | 2篇 |
2018年 | 3篇 |
2016年 | 5篇 |
2015年 | 8篇 |
2014年 | 8篇 |
2013年 | 22篇 |
2012年 | 13篇 |
2011年 | 28篇 |
2010年 | 14篇 |
2009年 | 12篇 |
2008年 | 17篇 |
2007年 | 18篇 |
2006年 | 18篇 |
2005年 | 17篇 |
2004年 | 8篇 |
2003年 | 6篇 |
2002年 | 13篇 |
2001年 | 11篇 |
2000年 | 16篇 |
1999年 | 16篇 |
1998年 | 7篇 |
1997年 | 5篇 |
1996年 | 7篇 |
1995年 | 2篇 |
1994年 | 2篇 |
1993年 | 5篇 |
1992年 | 6篇 |
1991年 | 10篇 |
1990年 | 5篇 |
1988年 | 8篇 |
1987年 | 4篇 |
1986年 | 5篇 |
1985年 | 8篇 |
1984年 | 3篇 |
1983年 | 9篇 |
1982年 | 3篇 |
1981年 | 7篇 |
1979年 | 2篇 |
1978年 | 4篇 |
1977年 | 4篇 |
1976年 | 2篇 |
1975年 | 5篇 |
1974年 | 6篇 |
1971年 | 1篇 |
1968年 | 1篇 |
1964年 | 3篇 |
1963年 | 1篇 |
排序方式: 共有394条查询结果,搜索用时 31 毫秒
81.
Relationships among msx gene structure and function in zebrafish and other vertebrates 总被引:6,自引:2,他引:4
Ekker M; Akimenko MA; Allende ML; Smith R; Drouin G; Langille RM; Weinberg ES; Westerfield M 《Molecular biology and evolution》1997,14(10):1008-1022
The zebrafish genome contains at least five msx homeobox genes, msxA, msxB,
msxC, msxD, and the newly isolated msxE. Although these genes share
structural features common to all Msx genes, phylogenetic analyses of
protein sequences indicate that the msx genes from zebrafish are not
orthologous to the Msx1 and Msx2 genes of mammals, birds, and amphibians.
The zebrafish msxB and msxC are more closely related to each other and to
the mouse Msx3. Similarly, although the combinatorial expression of the
zebrafish msx genes in the embryonic dorsal neuroectoderm, visceral arches,
fins, and sensory organs suggests functional similarities with the Msx
genes of other vertebrates, differences in the expression patterns preclude
precise assignment of orthological relationships. Distinct duplication
events may have given rise to the msx genes of modern fish and other
vertebrate lineages whereas many aspects of msx gene functions during
embryonic development have been preserved.
相似文献
82.
The MMS22L–TONSL heterodimer directly promotes RAD51‐dependent recombination upon replication stress 下载免费PDF全文
Wojciech Piwko Karun Mutreja Lepakshi Ranjha Diana Stafa Alexander Smirnov Mia ML Brodersen Ralph Zellweger Andreas Sturzenegger Pavel Janscak Massimo Lopes Matthias Peter Petr Cejka 《The EMBO journal》2016,35(23):2584-2601
Homologous recombination (HR) is a key pathway that repairs DNA double‐strand breaks (DSBs) and helps to restart stalled or collapsed replication forks. How HR supports replication upon genotoxic stress is not understood. Using in vivo and in vitro approaches, we show that the MMS22L–TONSL heterodimer localizes to replication forks under unperturbed conditions and its recruitment is increased during replication stress in human cells. MMS22L–TONSL associates with replication protein A (RPA)‐coated ssDNA, and the MMS22L subunit directly interacts with the strand exchange protein RAD51. MMS22L is required for proper RAD51 assembly at DNA damage sites in vivo, and HR‐mediated repair of stalled forks is abrogated in cells expressing a MMS22L mutant deficient in RAD51 interaction. Similar to the recombination mediator BRCA2, recombinant MMS22L–TONSL limits the assembly of RAD51 on dsDNA, which stimulates RAD51‐ssDNA nucleoprotein filament formation and RAD51‐dependent strand exchange activity in vitro. Thus, by specifically regulating RAD51 activity at uncoupled replication forks, MMS22L–TONSL stabilizes perturbed replication forks by promoting replication fork reversal and stimulating their HR‐mediated restart in vivo. 相似文献
83.
Solid-phase synthesis of peptides containing phosphoserine using phosphate tert.-butyl protecting group 总被引:4,自引:0,他引:4
J M Lacombe F Andriamanampisoa A A Pavia 《International journal of peptide and protein research》1990,36(3):275-280
In this paper, we report the solid-phase synthesis of peptides containing O-phosphonoserine using BOP as coupling reagent. Commercially available Fmoc amino-acids linked to p-alkoxybenzyl resin were used in the first step and Alloc amino acids in the following. Alloc group was removed by catalytic hydrostannolytic cleavage. Acid-labile side-chain protecting groups (including phosphate residue) were used. Thus, both removal of side-chain protecting groups and cleavage of the phosphopeptide from the resin were achieved in one step by treatment with TFA. Alloc serine was phosphorylated by the phosphoramidite method. This strategy enables the preparation of peptides with selectively phosphorylated residue and overcomes problems due to repetitive treatments with TFA and final cleavage with HF. 相似文献
84.
C. Perreault M. Gyger J. Boileau Y. Bonny S. Cousineau M. Lacombe R. Lavallee E. Tawil G. D'Angelo 《CMAJ》1983,129(9):969-974
In 25 patients receiving allogeneic bone marrow transplants methotrexate was used to prevent acute graft-versus-host disease (GVHD). Acute GVHD, grades 2 to 4, developed in only 5 (20%) of the patients. The incidence of acute GVHD in other series of recipients of bone marrow transplants has ranged from 5% to 76%. A review of the literature suggests that this variation cannot be completely accounted for by age, type of disease treated by transplantation or type of GVHD prophylaxis. However, transfusion of allogeneic lymphocytes that have not been completely inactivated by irradiation (e.g., in platelet and granulocyte preparations) and inadequate isolation-decontamination procedures may increase the probability of GVHD following bone marrow transplantation. 相似文献
85.
Effects of EDTA treatment upon the protein subunit composition and mechanical properties of mammalian single skeletal muscle fibers 总被引:9,自引:0,他引:9 下载免费PDF全文
Considerable interest has been focused on the role of myosin light chain LC(2) in the contraction of vertebrate striated muscle. A study was undertaken to further our investigations (Moss, R.L., G.G. Giulian, and M.L. Greaser, 1981, J. Biol. Chem., 257:8588-8591) of the effects of LC(2) removal upon contraction in skinned fibers from rabbit psoas muscles. Isometric tension and maximum velocity of shortening, V(max), were measured in fiber segments prior to LC(2) removal. The segments were then bathed at 30 degrees C for up to 240 min in a buffer solution containing 20 mM EDTA in order to extract up to 60 percent of the LC(2). Troponin C (TnC) was also partially removed by this procedure. Mechanical measurements were done following the EDTA extraction and the readditions of first TnC and then LC(2) to the segments. The protein subunit compositions of the same fiber segments were determined following each of these procedures by SDS PAGE of small pieces of the fiber. V(max) was found to decrease as the LC(2) content of the fiber segments was reduced by increasing the duration of extraction. EDTA treatment also resulted in substantial reductions in tension due mainly to the loss of TnC, though smaller reductions due to the extraction of LC(2) were also observed. Reversal of the order of recombination of LC(2) and TnC indicated that the reduction in V(max) following EDTA treatment was a specific effect of LC(2) removal. These results strongly suggest that LC(2) may have roles in determining the kinetics and extent of interaction between myosin and actin. 相似文献
86.
G Vanquelin M L Lacombe J Hanoune A D Strosberg 《Biochemical and biophysical research communications》1975,64(3):1076-1082
The chemical stability and release of isoproterenol bound by diazotation to an insoluble agarose matrix has been investigated. It is demonstrated, by a double labeling procedure ([3H]isoproterenol and [14C]-spacer arm), that the bound ligand is readily released in a soluble form. This occurs primarily through a chemical hydrolysis of the arm-linked ligand from the cyanogen bromide-activated agarose, and can be observed under extensive washing procedures as well as under more “physiological” incubation conditions. The instability of the agarose-arm linkage should lead to a critical analysis of physiological effects obtained with agarose bound hormones in vitro. 相似文献
87.
Nucleotide sequence analysis of the lemur beta-globin gene family: evidence for major rate fluctuations in globin polypeptide evolution 总被引:1,自引:0,他引:1
Lemur beta-related globin genes have been isolated and sequenced. Orthology
of prosimian and human epsilon-, gamma-, and beta-related globin genes was
established by dot-matrix analysis. All of these lemur globin genes
potentially encode functional beta-related globin polypeptides, though
precisely when the gamma-globin gene is expressed remains unknown. The
organization of the 18-kb brown lemur beta-globin gene cluster (5'
epsilon-gamma-[psi eta-delta]-beta 3') is consistent with its evolution by
contraction via unequal crossing-over from the putative ancestral mammalian
beta-globin gene cluster (5' epsilon-gamma- eta-delta-beta 3'). The dwarf
lemur nonadult globin genes are arranged as in the brown lemur. Similar
levels of synonymous (silent) nucleotide substitutions and noncoding DNA
sequence differences have accumulated between species in all of these
genes, suggesting a uniform rate of noncoding DNA divergence throughout
primate beta-globin gene clusters. These differences are comparable with
those observed in the nonfunctional psi eta pseudogene and have therefore
accumulated at the presumably maximal neutral rate. In contrast,
nonsynonymous (replacement) nucleotide substitutions show a significant
heterogeneity in distribution for both the same gene in different lineages
and different genes in the same lineage. These major fluctuations in
replacement but not silent substitution rates cannot be attributed to
changes in mutation rate, suggesting that changes in the rate of globin
polypeptide evolution in primates is not governed solely by variable
mutation rates.
相似文献
88.
Chromatography on DEAE-cellulose of an extract from etiolated leaves of sorghum ( Sorghum vulgare Pers. cv. INRA 450), a C4 plant, gave only one form of phosphoenol pyruvate carboxylase with functional and regulatory properties of a C3 type plant enzyme. Greening of the leaves resulted in a significant increase in activity. This increase was due to the appearance of a new form of the enzyme, which eluted at lower ionic strength and exhibited new properties. This form was glucose-6-P activated and showed a sigmoidal curve response to the concentration of the substrate phosphoerralpyruvate. These kinetic properties are typical of a C4 plant enzyme. 相似文献
89.
90.
G. Bonvento P. Lacombe E. T. MacKenzie† D. Fage J. Benavides L. Rouquier B. Scatton 《Journal of neurochemistry》1991,56(2):681-689
We have studied the nature and origin of the serotonergic innervation of two distinct anatomical cerebrovascular compartments, namely, small pial vessels and major cerebral arteries, in the rat. To this end, the levels of serotonin [5-hydroxytryptamine (5-HT)] and 5-hydroxyindoleacetic acid (5-HIAA) were measured by HPLC in both cerebrovascular compartments after either bilateral sympathectomy or destruction of the ascending serotonergic pathways, which originate from the raphe nuclei. We first showed that the small pial vessel samples were not contaminated by underlying cortical tissues through the use of an immunohistochemical approach that revealed the glia limitans, the most superficial cortical layer. Superior cervical ganglionectomy caused a marked decrease in noradrenaline concentrations in major cerebral arteries (-77%), although the reduction was less pronounced (-34%) in small pial vessels. Sympathectomy decreased by 33% 5-HT concentrations in the major cerebral arteries but was without effect on 5-HT levels in the small pial vessels. Destruction of the ascending serotonergic pathways (via local administration of 5,7-dihydroxytryptamine into the ventral tegmental area) produced a dramatic fall in 5-HT and 5-HIAA concentrations in both vascular compartments. To establish the authenticity of the serotonergic innervation, the synthesis of 5-HT [as assessed by measuring the accumulation of 5-hydroxytryptophan (5-HTP) after decarboxylase inhibition] was measured in the two vascular beds under control conditions and after destruction of the ascending serotonergic pathways. The rate of accumulation of 5-HTP was higher in the small pial vessels than in major cerebral arteries, an observation that indicates an important de novo synthesis of 5-HT in small pial vessels.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献