全文获取类型
收费全文 | 408篇 |
免费 | 121篇 |
专业分类
529篇 |
出版年
2021年 | 4篇 |
2020年 | 4篇 |
2018年 | 4篇 |
2017年 | 6篇 |
2016年 | 5篇 |
2015年 | 9篇 |
2014年 | 9篇 |
2013年 | 13篇 |
2012年 | 24篇 |
2011年 | 16篇 |
2010年 | 15篇 |
2009年 | 9篇 |
2008年 | 20篇 |
2007年 | 22篇 |
2006年 | 15篇 |
2005年 | 16篇 |
2004年 | 17篇 |
2003年 | 15篇 |
2002年 | 16篇 |
2001年 | 15篇 |
2000年 | 23篇 |
1999年 | 12篇 |
1998年 | 11篇 |
1997年 | 8篇 |
1996年 | 5篇 |
1995年 | 13篇 |
1994年 | 6篇 |
1993年 | 7篇 |
1992年 | 5篇 |
1991年 | 13篇 |
1990年 | 14篇 |
1989年 | 9篇 |
1988年 | 12篇 |
1987年 | 23篇 |
1986年 | 7篇 |
1985年 | 5篇 |
1984年 | 6篇 |
1983年 | 5篇 |
1982年 | 4篇 |
1981年 | 4篇 |
1979年 | 4篇 |
1978年 | 6篇 |
1977年 | 5篇 |
1976年 | 4篇 |
1975年 | 5篇 |
1974年 | 3篇 |
1965年 | 4篇 |
1957年 | 3篇 |
1937年 | 3篇 |
1933年 | 3篇 |
排序方式: 共有529条查询结果,搜索用时 15 毫秒
31.
32.
Garcia ML Lobsiger CS Shah SB Deerinck TJ Crum J Young D Ward CM Crawford TO Gotow T Uchiyama Y Ellisman MH Calcutt NA Cleveland DW 《The Journal of cell biology》2003,163(5):1011-1020
Neurofilaments are essential for acquisition of normal axonal calibers. Several lines of evidence have suggested that neurofilament-dependent structuring of axoplasm arises through an "outside-in" signaling cascade originating from myelinating cells. Implicated as targets in this cascade are the highly phosphorylated KSP domains of neurofilament subunits NF-H and NF-M. These are nearly stoichiometrically phosphorylated in myelinated internodes where radial axonal growth takes place, but not in the smaller, unmyelinated nodes. Gene replacement has now been used to produce mice expressing normal levels of the three neurofilament subunits, but which are deleted in the known phosphorylation sites within either NF-M or within both NF-M and NF-H. This has revealed that the tail domain of NF-M, with seven KSP motifs, is an essential target for the myelination-dependent outside-in signaling cascade that determines axonal caliber and conduction velocity of motor axons. 相似文献
33.
Unstable kinetochore-microtubule capture and chromosomal instability following deletion of CENP-E 总被引:7,自引:0,他引:7
Putkey FR Cramer T Morphew MK Silk AD Johnson RS McIntosh JR Cleveland DW 《Developmental cell》2002,3(3):351-365
A selective disruption of the mouse CENP-E gene was generated to test how this kinetochore-associated, kinesin-like protein contributes to chromosome segregation. The removal of CENP-E in primary cells produced spindles in which some metaphase chromosomes lay juxtaposed to a spindle pole, despite the absence of microtubules stably bound to their kinetochores. Most CENP-E-free chromosomes moved to the spindle equator, but their kinetochores bound only half the normal number of microtubules. Deletion of CENP-E in embryos led to early developmental arrest. Selective deletion of CENP-E in liver revealed that tissue regeneration after chemical damage was accompanied by aberrant mitoses marked by chromosome missegregation. CENP-E is thus essential for the maintenance of chromosomal stability through efficient stabilization of microtubule capture at kinetochores. 相似文献
34.
Rao MV Garcia ML Miyazaki Y Gotow T Yuan A Mattina S Ward CM Calcutt NA Uchiyama Y Nixon RA Cleveland DW 《The Journal of cell biology》2002,158(4):681-693
The COOH-terminal tail of mammalian neurofilament heavy subunit (NF-H), the largest neurofilament subunit, contains 44-51 lysine-serine-proline repeats that are nearly stoichiometrically phosphorylated after assembly into neurofilaments in axons. Phosphorylation of these repeats has been implicated in promotion of radial growth of axons, control of nearest neighbor distances between neurofilaments or from neurofilaments to other structural components in axons, and as a determinant of slow axonal transport. These roles have now been tested through analysis of mice in which the NF-H gene was replaced by one deleted in the NF-H tail. Loss of the NF-H tail and all of its phosphorylation sites does not affect the number of neurofilaments, alter the ratios of the three neurofilament subunits, or affect the number of microtubules in axons. Additionally, it does not reduce interfilament spacing of most neurofilaments, the speed of action potential propagation, or mature cross-sectional areas of large motor or sensory axons, although its absence slows the speed of acquisition of normal diameters. Most surprisingly, at least in optic nerve axons, loss of the NF-H tail does not affect the rate of transport of neurofilament subunits. 相似文献
35.
The centromere is a chromosomal locus that ensures delivery of one copy of each chromosome to each daughter at cell division. Efforts to understand the nature and specification of the centromere have demonstrated that this central element for ensuring inheritance is itself epigenetically determined. The kinetochore, the protein complex assembled at each centromere, serves as the attachment site for spindle microtubules and the site at which motors generate forces to power chromosome movement. Unattached kinetochores are also the signal generators for the mitotic checkpoint, which arrests mitosis until all kinetochores have correctly attached to spindle microtubules, thereby representing the major cell cycle control mechanism protecting against loss of a chromosome (aneuploidy). 相似文献
36.
37.
Takahashi M Rapley E Biggs PJ Lakhani SR Cooke D Hansen J Blair E Hofmann B Siebert R Turner G Evans DG Schrander-Stumpel C Beemer FA van Vloten WA Breuning MH van den Ouweland A Halley D Delpech B Cleveland M Leigh I Chapman P Burn J Hohl D Görög JP Seal S Mangion J 《Human genetics》2000,106(1):58-65
Familial cylindromatosis is an autosomal dominant predisposition to multiple neoplasms of the skin appendages. The susceptibility gene has previously been mapped to chromosome 16q12-q13 and has features of a recessive oncogene/tumour suppressor gene. We have now evaluated 19 families with this disease by a combination of genetic linkage analysis and loss of heterozygosity in cylindromas from affected individuals. All 15 informative families show linkage to this locus, providing no evidence for genetic heterogeneity. Recombinant mapping has placed the gene in an interval of approximately 1 Mb. There is no evidence, between families, of haplotype sharing that might be indicative of common founder mutations. 相似文献
38.
Oxidation versus aggregation - how do SOD1 mutants cause ALS? 总被引:9,自引:0,他引:9
39.
Isoprene (2-methyl-1,3 butadiene) is a low-molecular-weight hydrocarbon emitted in large quantities to the atmosphere by vegetation and plays a large role in regulating atmospheric chemistry. Until now, the atmosphere has been considered the only significant sink for isoprene. However, in this study we performed both in situ and in vitro experiments with soil from a temperate forest near Ithaca, N.Y., that indicate that the soil provides a sink for atmospheric isoprene and that the consumption of isoprene is carried out by microorganisms. Consumption occurred rapidly in field chambers (672.60 +/- 30.12 to 2,718.36 +/- 86.40 pmol gdw day) (gdw is grams [dry weight] of soil; values are means +/- standard deviations). Subsequent laboratory experiments confirmed that isoprene loss was due to biological processes: consumption was stopped by autoclaving the soil; consumption rates increased with repeated exposure to isoprene; and consumption showed a temperature response consistent with biological activity (with an optimum temperature of 30 degrees C). Isoprene consumption was diminished under low oxygen conditions (120 +/- 7.44 versus 528.36 +/- 7.68 pmol gdw day under ambient O(2) concentrations) and showed a strong relationship with soil moisture. Isoprene-degrading microorganisms were isolated from the site, and abundance was calculated as 5.8 x 10 +/- 3.2 x 10 cells gdw. Our results indicate that soil may provide a significant biological sink for atmospheric isoprene. 相似文献
40.
Cary JW OBrian GR Nielsen DM Nierman W Harris-Coward P Yu J Bhatnagar D Cleveland TE Payne GA Calvo AM 《Applied microbiology and biotechnology》2007,76(5):1107-1118
The aflatoxin-producing fungi, Aspergillus flavus and A. parasiticus, form structures called sclerotia that allow for survival under adverse conditions. Deletion of the veA gene in A. flavus and A. parasiticus blocks production of aflatoxin as well as sclerotial formation. We used microarray technology to identify genes differentially
expressed in wild-type veA and veA mutant strains that could be involved in aflatoxin production and sclerotial development in A. flavus. The DNA microarray analysis revealed 684 genes whose expression changed significantly over time; 136 of these were differentially
expressed between the two strains including 27 genes that demonstrated a significant difference in expression both between
strains and over time. A group of 115 genes showed greater expression in the wild-type than in the veA mutant strain. We identified a subgroup of veA-dependent genes that exhibited time-dependent expression profiles similar to those of known aflatoxin biosynthetic genes
or that were candidates for involvement in sclerotial production in the wild type. 相似文献