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91.
Yoon HJ Hashimoto W Miyake O Okamoto M Mikami B Murata K 《Protein expression and purification》2000,19(1):84-90
A bacterium Sphingomonas sp. A1 produces three kinds of alginate lyases [A1-I (66 kDa), A1-II (25 kDa), and A1-III (40 kDa)] from a single precursor, through posttranslational processing. Overexpression systems for these alginate lyases were constructed in Escherichia coli cells by controlling of the lyase genes under T7 promoter and terminator. Expression levels of A1-I, A1-II, and A1-III in E. coli cells were 3.50, 3.04, and 2.13 kU/liter of culture, respectively, and were over 10-fold higher than those in Sphingomonas sp. A1 cells. Purified A1-I, A1-II, and A1-III from E. coli cells were monomeric enzymes with molecular masses of 63, 25, and 40 kDa, respectively. The depolymerization pattern of alginate with A1-I and A1-II indicated that both enzymes cleaved the glycosidic bond of the polymer endolytically and by beta-elimination reaction. A1-II preferred polyguluronate rather than polymannuronate and released tri- and tetrasaccharides, which have unsaturated uronyl residues at the nonreducing terminal, from alginate as the major final products. A1-I acted equally on both homopolymers and produced di- and trisaccharides as the final products. 相似文献
92.
Composite and clinal distribution of Glycine soja in Japan revealed by RFLP analysis of mitochondrial DNA 总被引:4,自引:0,他引:4
A. Tozuka H. Fukushi T. Hirata M. Ohara A. Kanazawa T. Mikami J. Abe Y. Shimamoto 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1998,96(2):170-176
Wild soybean (Glycine soja Sieb. et Zucc.), regarded as the progenitor of cultivated soybean [G. max (L.) Merr.], is widely distributed in East Asia. We have collected 1097 G. soja plants from all over Japan and analyzed restriction fragment length polymorphisms (RFLPs) of mitochondrial DNA (mtDNA) in
them. Based on the RFLPs detected by gel-blot analysis, using coxII and atp6 as probes, the collected plants were divided into 18 groups. Five mtDNA types accounted for 94% of the plants examined. The
geographic distribution of mtDNA types revealed that, in many regions, wild soybeans grown in Japan consisted of a mixture
of plants with different types of mtDNA, occasionally even within sites. Some of the mtDNA types showed marked geographic
clines among the regions. Additionally, some wild soybeans possessed mtDNA types that were identical to those widely detected
in cultivated soybeans. Our results suggest that the analysis of mtDNA could resolve the maternal lineage among plants of
the genus Glycine subgenus Soja.
Received: 16 June 1997/Accepted: 5 August 1997 相似文献
93.
M. Senda Y. Onodera T. Mikami 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1998,96(6-7):964-968
The mitochondrial atpA gene sequence of the normal fertile sugarbeet (cv ‘TK81-0’) exists in one full-length version and one truncated version,
both of which are present in normal stoichiometry and have a 406-bp segment in common. The PCR approach as well as prolonged
exposure of Southern blots indicates that the products of the recombination across the 406-bp repeat are present in substoichiometric
amounts in the ‘TK81-0’ genome. Intriguingly, one of these substoichiometric sequence arrangements was revealed to be preferentially
amplified in an evolutionary lineage that led to a cytoplasmic male-sterile variant [I-12CMS(2)] in wild beets. We also found
the 406-bp repeat to be part of a 6.5-kb repeat in the mitochondrial genome of I-12CMS(2). This 6.5-kb duplication is likely
to involve recombination between two sets of repeats (the above-mentioned 406-bp repeat and a 7-bp repeat) in an ancestral
beet mitochondria.
Received: 4 October 1997 / Accepted: 31 October 1997 相似文献
94.
T. Koike S. Kato Y. Shimamoto K. Kitamura S. Kawano K. Ueda T. Mikami 《Plant biology (Stuttgart, Germany)》1998,111(1):87-91
The amount and distribution of mitochondrial (mt) DNA restriction fragment length polymorphism was determined among individual tree samples of two Japanese beech species, Fagus crenata and F.japonica. Individual plants were collected from 16 F. crenata populations throughout the range of the species, and from three F. japonica populations. We detected enough variation to characterize eleven and three chondriome types in F. crenata and F.japonica, respectively. The grouping of beech chondriome types based upon the cladistic analysis of mtDNA polymorphism allowed us to recognize the apparent geographical patterns of mtDIMA diversity: the resulting three main groups occupied distinct geographic areas. This geographic differentiation is likely to reflect the history of the Japanese beech forests after the last glacial period of the Pleistocene. In addition, the mtDNA polymorphism encountered within F. crenata encompassed all the variation observed in F.japonica. Our result suggests the need for re-evaluation of their phylogenetic relationships. 相似文献
95.
Elham Fakhrejahani Masae Torii Toshiyuki Kitai Shotaro Kanao Yasufumi Asao Yohei Hashizume Yoshiki Mikami Iku Yamaga Masako Kataoka Tomoharu Sugie Masahiro Takada Hironori Haga Kaori Togashi Tsuyoshi Shiina Masakazu Toi 《PloS one》2015,10(10)
Photoacoustic tomography is a recently developed imaging modality that can provide high spatial-resolution images of hemoglobin distribution in tissues such as the breast. Because breast cancer is an angiogenesis-dependent type of malignancy, we evaluated the clinical acceptability of breast tissue images produced using our first prototype photoacoustic mammography (PAM) system in patients with known cancer. Post-excisionally, histological sections of the tumors were stained immunohistochemically (IHC) for CD31 (an endothelial marker) and carbonic anhydrase IX (CAIX) (a marker of hypoxia). Whole-slide scanning and image analyses were used to evaluate the tumor microvessel distribution pattern and to calculate the total vascular perimeter (TVP)/area for each lesion. In this clinical study, 42 lesions were primarily scanned using PAM preoperatively, three of which were reported to be benign and were excluded from statistical analysis. Images were produced for 29 out of 39 cancers (visibility rate = 74.4%) at the median depth of 26.5 (3.25–51.2) mm. Age, menopausal status, body mass index, history of neoadjuvant treatment, clinical stage and histological tumor angiogenesis markers did not seem to affect the visibility. The oxygen saturation level in all of the measured lesions was lower than in the subcutaneous counterpart vessels (Wilcoxon test, p value<0.001), as well as in the counterpart contralateral normal breast region of interest (ROI) (Wilcoxon test, p value = 0.001). Although the oxygen saturation level was not statistically significant between CAIX-positive vs. -negative cases, lesional TVP/area showed a positive correlation with the oxygen saturation level only in the group that had received therapy before PAM. In conclusion, the vascular and oxygenation data obtained by PAM have great potential for identifying functional features of breast tumors. 相似文献
96.
Taro Masuda Fumiyuki Goto Bunzo Mikami 《Biochemical and biophysical research communications》2010,400(1):94-99
Ferritins are ubiquitous iron storage proteins. Recently, we identified a novel metal-binding site, transit site, in the crystal structure of phytoferritin. To elucidate the function of the transit site in ferritin from other species, we prepared transit-site-deficient mutants of human H ferritin, E140A and E140Q, and their iron oxidation kinetics was analyzed. The initial velocities of iron oxidization were reduced in the variants, especially in E140Q. The crystal structure of E140Q showed that the side chain of the mutated Gln140 was fixed by a hydrogen bond, whereas that of native Glu140 was flexible. These results suggest that the conserved transit site also has a function to assist with the metal ion sequestration to the ferroxidase site in ferritins from vertebrates. 相似文献
97.
Tae Sato Satoshi Ito Yasushi Mitsuda Norihisa Soen 《Landscape and Ecological Engineering》2010,6(1):89-98
We examined the impacts of land-use history on the species composition and diversity of a warm-temperate riparian forest landscape
in Kyushu, southern Japan, focusing on the relationship between evergreen oaks and deciduous trees in natural and seminatural
forests. The species composition of 59 plots was classified into four types (A to D). Type A, which showed a significant bias
towards sites not subject to nonforest land use since 1947, had high species diversity consisting of (1) many lucidophyllous
components of the region, including the rare indigenous oak Quercus hondae, and (2) summergreen tree species of varying dominance and number representing unique or locally rare elements of the riparian
landscape in this warm-temperate region. Type B was dominated by a common species of oak, Q. glauca, and displayed less clear distribution bias with land-use history. In contrast to types A and B, types C and D, which were
characterized by high dominance of deciduous trees, had negative bias away from sites that had been under forest land use
in 1947. Presumably, intensive anthropogenic disturbances associated with nonforest land uses had expanded the habitats for
deciduous trees. This phenomenon was represented by the establishment of forests (type D) dominated by Ulmus davidiana var. japonica (UDJ) after it had been released from the suppression of evergreen forest trees during a period of nonforest land use that
prevents the successful recovery of evergreen trees. From these results we conclude that the impacts of land-use history on
the diversity of warm-temperate riparian forest landscape are multiphased: a period of nonforest land use has a strong negative
impact on lucidophyllous forest trees represented by the rare indigenous oak Q. hondae; release from the suppressive effects of the lucidophyllous species then encourages establishment of locally rare deciduous
tree flora represented by UDJ, which continue to persist for decades after abandonment of nonforest land use. 相似文献
98.
Under laboratory conditions, spores of ectomycorrhizal fungi usually germinate very poorly or not at all. In a previous study,
we showed that spores of the ectomycorrhizal fungus Suillus bovinus germinated through the combination of activated charcoal treatment of media and co-culture with seedlings of Pinus densiflora, which suggested that some substances contained in root exudates induced the germination. Among the compounds reported from
root exudates, flavonoids have been elucidated to play various and substantial roles in plant–microbe interactions; we therefore
investigated the effects of flavonoids on basidiospore germination of S. bovinus by the diffusion gradient assay on water agar plates pretreated with charcoal powder. Seven out of the 11 flavonoids tested,
hesperidin, morin, rutin, quercitrin, naringenin, genistein, and chrysin, had greater effects than controls, whereas flavone,
biochanin A, luteolin, and quercetin showed no positive effects. The effective concentration presumably corresponded to several
micromolar levels, which was equivalent to those effective for pollen development, nod gene induction, and spore germination of F. solani f. sp. pisi and AM fungi. The results suggest that flavonoids play a role as signaling molecules in symbiotic relationships between woody
plants and ectomycorrhizal fungi. 相似文献
99.
100.
Taro Mikami Keiichiro Yoshida Hajime Sawada Michiyo Esaki Kazunori Yasumura Michio Ono 《Biological research》2015,48(1)