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51.
The application of sieving techniques to bulk samples from the Ashizawa Formation, Futaba Group (Lower Coniacian) of northeastern
Honshu, Japan, has yielded well-preserved mesofossil assemblages comparable with those recently described from eastern North
America, Europe, and central Asia. Among the most abundant and distinctive components of these assemblages are fusiform fruits
that are assigned here to a new genus and species, Hironoia fusiformis gen. et sp. nov. The fruits developed from an epigynous ovary with three to four locules. Each locule bears one seed and
has a distinctive dorsal germination valve. These features of the fruit, along with the adnate calyx, indicate an affinity
to extant Cornales and specifically the Cornaceae sensu lato. The recognition of an unequivocal cornalean fruit in the Early
Coniacian–Early Santonian of Japan provides the earliest record of this group in the fossil record. It also establishes a
minimum age for the early divergence of the asterid clade, a major group of living angiosperms comprising more than a third
of all species of extant flowering plants.
Electronic Publication 相似文献
52.
The rearing condition necessary for behavioral compensation after sensory deprivation was investigated in the cricket Gryllus bimaculatus. The right-cercus-ablated cricket was reared in a glass vial with a slightly larger diameter than the body length of the cricket. After two weeks of rearing in the vial, the air-puff-evoked escape behavior of the cricket was investigated. The response rate (relative occurrence of the escape behavior after a standard air puff) obtained was identical with that of crickets reared in a large cage. On the other hand, unlike crickets reared in a large cage, the distorted escape directional property of the cricket reared in the vial was not compensated at all. Control experiments proved that the restraint in the vial did not affect the motor system, and the air motion from environments was not essential for the compensational recovery of the escape direction. Therefore, the ablated crickets required spontaneous walking in order to compensate the directionality of their escape. A self-generated wind caused by spontaneous walking appears necessary for the crickets to realize the defect of their sensory system and to compensate the related escape behavior. A hypothesis for the compensation mechanism based on the efference copy signal is proposed. 相似文献
53.
Malki A Caldas T Parmeggiani A Kohiyama M Richarme G 《Biochemical and biophysical research communications》2002,296(3):749-754
The elongation factor EF-Tu carries aminoacyl-tRNAs to the A-site of the ribosome during the elongation process of protein biosynthesis. We, and others, have recently reported that the Escherichia coli EF-Tu interacts with unfolded and denatured proteins and behaves like a chaperone in protein folding and protection against protein thermal denaturation. In this study, we have identified EF-Tu binding sites in protein substrates by screening cellulose-bound peptides scanning the sequences of several proteins. The binding motifs recognized by EF-Tu in protein substrates are also recognized by the chaperone DnaK and mainly consist of hydrophobic clusters. EF-Tu interacts as efficiently as DnaK with the membrane spanning sequence of the membrane protein phospholemman and with the signal sequence of alkaline phosphatase. It interacts less efficiently with several other hydrophobic clusters of lysozyme and alkaline phosphatase, which are also DnaK substrates and fails to bind to several DnaK binding sites. Our results suggest that EF-Tu, like DnaK, interacts albeit more weakly with the hydrophobic regions of substrate protein and are consistent with the hypothesis that it possesses chaperone properties. 相似文献
54.
Dietary Zn deficiency does not influence systemic blood pressure and vascular nitric oxide signaling in normotensive rats 总被引:1,自引:1,他引:0
Sato M Kurihara N Moridaira K Sakamoto H Tamura J Wada O Yanagisawa H 《Biological trace element research》2003,91(2):157-171
Because zinc (Zn) is an important component for cell protection against certain oxygen species, it has been suggested that
Zn deficiency impairs the potent oxidant defense capacity, which is constitutively provided in the vascular system. However,
the influence of dietary Zn deficiency on systemic blood pressure and vascular system is controversial and unclear. We therefore
examine the effect of dietary Zn deficiency on systemic blood pressure, a potent superoxide scavenger, aortic Cu/Zn superoxide
dismutase (SOD) activity, a most representative synthase of the endothelium-derived relaxing factor, and aortic endothelial
nitric oxide synthase (eNOS) expression. Furthermore, the direct effects of intravenous administration of NOS inhibitor, N
ω-nitro-l-arginine methyl ester (l-NAME), and a SOD mimetic compound, tempol, in normotensives were tested in Wistar-Kyoto (WKY) rats. A Zn-deficient diet (4
wk) contributed to growth retardation, the decrease in thymus weight, and the lower levels of serum Zn compared with the standard
diet group. However, no significant difference in conscious systolic and diastolic blood pressure was found in the Zn-deficiency
group. The administration of l-NAME caused an increase in the mean arterial pressure (MAP) levels in the two groups of rats and the involvement of the vasodilator
nitric oxide (NO) in the regulation of systemic BP in the normotensive state. On the other hand, administration of the superoxide
scavenger, tempol, led to a decrease in MAP levels in the two groups of rats, indicating the participation of the oxygen free
radical, superoxide, in the maintenance of the systemic BP in a normotensive state. There were no significant differences
between the Zn-deficient diet group and the standard diet group in the normotensive state. eNOS expression and Cu/Zn SOD activity
in the aorta were also intact in Zn-deficient normotensive rats. These findings suggest that the 4 wk of Zn deficiency was
inadequate to alter systemic blood pressure and focal NO signaling in the normotensive state. Long-term Zn deficiency affects
the neuronal, immune, and hematopoietic systems, which contribute to systemic and/or local circulation. However, Zn deficiency
alone does not cause hypertension and local vascular dysfunction in the normotensive state. 相似文献
55.
Mutations in the Connexin-26 gene (Cx 26, GJB2) are the most common cause of hereditary nonsyndromic sensorineural hearing loss (SNHL). DNA analysis of the Cx 26 gene in deaf or hard-of-hearing individuals frequently demonstrates heterozygosity despite the fact that most mutations are known to be recessive. A 342-kb deletion in a gene adjacent to Cx 26, the Connexin-30 gene (Cx 30, GJB6), has been reported to cause deafness in the homozygous state or in combination with heterozygous mutations in Cx 26 (digenic inheritance). We have analyzed deaf or hard-of-hearing Cx 26 heterozygotes and individuals with no mutations in Cx 26 for this Cx 30 deletion. We found that 4/20 (20%) of the Cx 26 heterozygotes are heterozygous for this deletion and that no individuals were homozygous for the Cx 30 deletion. Cx 30 deletion analysis is recommended for all individuals with nonsyndromic SNHL following Cx 26 sequencing that does not demonstrate two recessive mutations. 相似文献
56.
Gross structural changes and neuropil formation in the brain during development were described in Idiosepius paradoxus, a sepioid that we chose as a model cephalopod. The brain originates in 4 pairs of ectodermal placodes, which occur separately in the embryonic surface undergoing epiboly. In the final period of epiboly, neuroblasts internalize from the placodes and gather into 4 pairs of ganglionic masses. The ganglionic masses assemble into a ring-like cluster encircling the inner yolk and the foregut anlage, gradually integrated into the 4 domains of a massive brain, a subesophageal mass (SBM), a supraesophageal mass (SPM), and a pair of optic lobes. In the early brain, neuropil forms a framework composed of a longitudinal ladder lying in the SBM, and a transverse arch standing on the lateral sides of the SBM and crossing the SPM. Differentiation of brain lobes proceeds from ventral to dorsal along this framework; first the magnocellular lobes and the posterior pedal lobe appear first in the SBM, the other lobes in the SBM and the basal lobes follow in the proximal region of the SPM, and the accessory lobes develop last in the most dorsal zone of the SPM. In the hatchlings, the brain lobes show almost the same arrangement as in the adults, but the accessory lobes, particularly the vertical lobe, are much smaller than those in the adults. Comparison of the present results with those in the teuthoid and the octopod indicates that developmental sequences of the brain are highly conserved in the coleoid cephalopods. 相似文献
57.
Arie M Matsuda H Furuhashi K Takagi M 《The Journal of General and Applied Microbiology》2000,46(5):257-262
Phylogenetic relationships of several species within the n-alkane assimilating Candida yeasts were investigated by using characters from the nucleotide sequence of the variable D1/D2 region at the 5' end of a large-subunit (26S) ribosomal DNA (rDNA) gene. First the nucleotide sequences of D1/D2 domain of Candida sp. 1098 (formerly identified as C. tropicalis 1098) and its dicarboxylic acid-producing-mutant strain M1210 were investigated. These two nucleotide sequences were identical and lacked only one base pair compared with that of C. maltosa CBS 5611 (type strain), and they were identified as C. maltosa. We then showed that C. maltosa IFO 1978 (formerly identified as C. cloacae) and C. maltosa IFO 1975 (formerly identified as C. subtropicalis) had the same nucleotide sequence and had only one base pair substitution compared with C. maltosa CBS 5611 (type strain), which is consistent with conventional classification. We also found that another widely studied n-alkane assimilating Candida yeast, C. tropicalis pk233, to be C. viswanathii. 相似文献
58.
59.
Recent molecular studies investigating higher-level phylogeneticsof coleoid cephalopods (octopuses, squids and cuttlefishes)have produced conflicting results. A wide range of sequencealignment and analysis methods are used in cephalopod phylogeneticstudies. The present study investigated the effect of commonlyused alignment and analysis methods on higher-level cephalopodphylogenetics. Two sequence homology methods: (1) eye alignment,(2) implied alignment, and three analysis methods: (1) parsimony,(2) maximum likelihood, (3) Bayesian methodologies, were employedon the longest sequence dataset available for the coleoid cephalopods,comprising three mitochondrial and six nuclear loci. The datawere also tested for base composition heterogeneity, which wasdetected in three genes and resolved using RY coding. The Octopoda,Argonautoidea, Oegopsida and Ommastrephidae are monophyleticin the phylogenies resulting from each of the alignment andanalysis combinations. Furthermore, the Bathyteuthidae are thesister taxon of the Oegopsida in each case. However many relationshipswithin the Coleoidea differed depending upon the alignment andanalysis method used. This study demonstrates how differencesin alignment and analysis methods commonly used in cephalopodphylogenetics can lead to different, but often highly supported,relationships. (Received 15 December 2006; accepted 1 September 2007) 相似文献
60.
Akiko Sumi Jun Akiba Sachiko Ogasawara Masamichi Nakayama Yoriko Nomura Makiko Yasumoto Sakiko Sanada Osamu Nakashima Toshi Abe Hirohisa Yano 《PloS one》2015,10(3)