全文获取类型
收费全文 | 387篇 |
免费 | 13篇 |
出版年
2023年 | 1篇 |
2022年 | 7篇 |
2021年 | 6篇 |
2020年 | 2篇 |
2019年 | 2篇 |
2018年 | 13篇 |
2017年 | 8篇 |
2016年 | 11篇 |
2015年 | 22篇 |
2014年 | 21篇 |
2013年 | 31篇 |
2012年 | 34篇 |
2011年 | 42篇 |
2010年 | 16篇 |
2009年 | 13篇 |
2008年 | 23篇 |
2007年 | 38篇 |
2006年 | 17篇 |
2005年 | 16篇 |
2004年 | 19篇 |
2003年 | 21篇 |
2002年 | 8篇 |
2001年 | 1篇 |
2000年 | 1篇 |
1999年 | 4篇 |
1998年 | 2篇 |
1997年 | 3篇 |
1996年 | 2篇 |
1995年 | 1篇 |
1994年 | 3篇 |
1991年 | 5篇 |
1990年 | 1篇 |
1988年 | 2篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1981年 | 1篇 |
1961年 | 1篇 |
排序方式: 共有400条查询结果,搜索用时 15 毫秒
1.
Anna L. Trifillis Myong Won Kahng 《In vitro cellular & developmental biology. Plant》1990,26(5):441-446
Summary We have developed an in vitro model of human papillary collecting duct cells isolated from cadaver kidneys using methods similar
to those we previously reported for the isolation of human proximal tubule cells. To date we have isolated papillary collecting
duct cells from 100 normal human kidneys. Papillae were dissected and digested in Cellgro containing 400 U/ml collagenase.
Cells were plated on fibronectin-coated culture flasks at a density of 104 live cells/ml in Cellgro supplemented with insulin and 10% fetal bovine serum. Confluent monolayers, which were able to withstand
600 mOsm for 8 h, were obtained within 10 to 15 d. Cells of primary isolates and first passages exhibited epithelial cell ultrastructure
including cell junctions, microvilli, and cilia. A dark-brown reaction product was observed in these cells when stained by
the immunoperoxidase method with peroxidase-labeled peanut lectin (Arachis hypogaea), which binds specifically to human distal tubule and collecting duct cells. These cells were negative for Factor-VIII (a
marker for endothelial cells) and γ-glutamyltransferase (a marker for proximal tubule cells). High activities of the glycolytic
enzyme pyruvate kinase and arginine vasopressin-stimulated cAMP production in these cells are consistent with a distal nephron
origin. The results indicate that human collecting duct cells can be isolated and cultured to provide an in vitro system to
probe pathogenetic mechanisms of potential nephrotoxins.
Part of this work was presented at a Symposium of the Center for Alternatives to Animal Testing, April 4–5, 1989, Johns Hopkins
Medical Institutions, Baltimore, MD 21205.
This work was supported in part by grants R01-AI24179, PO1-A804393 for the Public Health Service, U.S. Department of Health
and Human Services, and by a grant from the National Kidney Foundation, Baltimore, MD affiliate. 相似文献
2.
Yeehn Yeeh Soon Suk Kang Hye Gi Chung Mun Su Chung Myong Gi Chung 《Journal of plant research》1996,109(2):161-168
Vitex rotundifolia L.f. is a woody perennial and has sexual and asexual modes of reproduction. Allozyme study was conducted on 550 plants in
13 Korean populations. The levels of genetic variability and divergence within and among populations, respectively, are considerably
lower and higher than the mean values for woody plants with similar life history tralts. Mean percentage of polymorphic loci
(P
P), mean number of alleles per locus (A
P), and mean genetic diversity (He
P) within populations ofV. rotundifolia were: 16.7%, 1.21, and 0.047. On average, about 79% of the total variation inV. rotundifolia was common to all populations (meanG
ST=0.208). In addition, significant differences in allele frequencies among populations were found in all polymorphic loci examined
(P<0.001). On the other hand, levels of genotypic diversity within and among populations were moderate. About 44% (18/41) of
multilocus genotypes were “local genotypes” (genotypes occurring in only one population), whereas only one “widespread genotype”
(genotypes occurring in more than 75% of the populations) were detected. The mean number of multilocus genotypes per population
(G) and mean genotypic diversity index (D
G) were 8.4 and 0.74, respectively. Most common multilocus genotypes found in populations were homozygous for five polymorphic
loci. The abundance of ramets of these genets is responsible for the low levels of expected heterozygosity within populations.
The results indicate that clonal reproduction may act as an enhancer of genetic drift by reducing effective size of local
populations ofV. rotundifolia. 相似文献
3.
To better understand the patterns of variability and distributions ofHemerocallis in Korea, 53 locations were visited and measurements of 19 morphological and phenological characters were taken on plants
directly from their natural habitats. For morphometric analysis, 10 plants from each of 34 populations and five herbarium
specimens ofH. middendorffii were used and the data from 12 quantitative characters was analyzed using univariate analysis. Except the littoral populations
of Cheju, Hong, Taehuksan, and Sohuksan Islands (H. hongdoensis M. Chung & S. Kang), three peninsular KoreanHemerocallis species can be recognized mainly in South Korea:H. hakuunensis Nakai (=H. micrantha Nakai, growing on southern, central, and northwestern Korea);H. thunbergii Baker (=H. coreana Nakai, found on southeastern and central Korea); andH. middendorffii Tr. et Mey. (central and northeastern Korea). Morphological and phenological features contributing to recognition of the
three groups were; color of perianth, shape of roots, shape of inflorescence, flowering time, odor, length of inflorescence,
width of the lowest bracts, length of perianth tube enclosing a ovary, width of the inner perianth lobes. Natural hybridization
seems to be rare in KoreanHemerocallis. It appears that the KoreanHemerocallis species are relatively well characterized by their distribution patterns, phenology, and habitats compared with the JapaneseHemerocallis species. 相似文献
4.
Moon Woo Chun Sung Pil Choi Myong Jung Kim Chol Joon Bae Hyung Ryong Moon Hee-Doo Kim 《Nucleosides, nucleotides & nucleic acids》2013,32(4-5):615-616
Abstract Novel 1,3-oxathiolanyl pyrimidine nucleosides with 5-hydroxymethyl substituent were synthesized starting from d-mannose and evaluated for antiviral activities against HIV-1, HSV type 1,2 and HCMV. 相似文献
5.
This paper presents the dynamic modeling of a flexible tail for a robotic fish. For this purpose firstly, the flexible tail was simplified as a slewing beam actuated by a driving moment. The governing equation of the flexible tail was derived by using the Euler-Bernoulli theory. In this equation, the resistive forces were estimated as a term analogous to viscous damping. Then, the modal analysis method was applied in order to derive an analytical solution of the governing equation, by which the relationship between the driving moment and the lateral movement of the flexible tail was described. Finally, simulations and experiments were carried out and the results were compared to verify the accuracy of the dynamic model. It was proved that the dynamic model of a fish robot with a flexible tail fin well explains the real behavior of robotic fish in underwater environment. 相似文献
6.
Lee Yeon Hee Bang Eun-Sook Lee Ji-Hyun Lee Jung-Dong Kang Dae Ryong Hong Jeong Lee Jae-Myeong 《Biological trace element research》2019,188(2):316-325
Biological Trace Element Research - We measured serum concentrations of trace elements and evaluated their clinical significance in relation to treatment outcomes of critically ill patients. A... 相似文献
7.
8.
Jeong LS Kim MJ Kim HO Gao ZG Kim SK Jacobson KA Chun MW 《Bioorganic & medicinal chemistry letters》2004,14(19):4851-4854
On the basis of high binding affinity at the A(3) adenosine receptor of 3'-aminoadenosine derivatives with hydrogen bonding donor ability, novel 3'-ureidoadenosine analogues were synthesized from 1,2:5,6-di-O-isopropylidene-d-glucose in order to lead to stronger hydrogen bonding than the corresponding 3'-aminoadenosine derivatives. However, the synthesized 3'-ureidoadenosine analogues were totally devoid of binding affinity, because 3'-urea moiety caused steric and electrostatic repulsions at the binding site of the A(3) adenosine receptor, leading to conformational distortion. 相似文献
9.
Kim DW Yoon CS Eum WS Lee BR An JJ Lee SH Lee SR Ahn JY Kwon OS Kang TC Won MH Cho SW Lee KS Park J Choi SY 《Molecules and cells》2004,18(3):314-319
gamma-Aminobutyrate transaminase (GABA-T), a key enzyme of the GABA shunt, converts the major inhibitory neurotransmitter, GABA, to succinic semialdehyde. Although GABA-T is a pivotal factor implicated in the pathogenesis of various neurological disorders, its function remains to be elucidated. In an effort to clarify the structural and functional roles of specific lysyl residue in human brain GABA-T, we constructed human brain GABA-T mutants, in which the lysyl residue at position 357 was mutated to various amino acids including asparagine (K357N). The purified mutant GABA-T enzymes displayed neither catalytic activity nor absorption bands at 330 and 415 nm that are characteristic of pyridoxal-5'-phosphate (PLP) covalently linked to the protein. The wild type apoenzyme reconstituted with exogenous PLP had catalytic activity, while the mutant apoenzymes did not. These results indicate that lysine 357 is essential for catalytic function, and is involved in binding PLP at the active site. 相似文献
10.
The DNA repair machinery must locate and repair DNA damage all over the genome. As nucleosomes inhibit DNA repair in vitro, it has been suggested that chromatin remodeling might be required for efficient repair in vivo. To investigate a possible contribution of nucleosome dynamics and chromatin remodeling to the repair of UV-photoproducts in nucleosomes, we examined the effect of a chromatin remodeling complex on the repair of UV-lesions by Micrococcus luteus UV endonuclease (ML-UV endo) and T4-endonuclease V (T4-endoV) in reconstituted mononucleosomes positioned at one end of a 175-bp long DNA fragment. Repair by ML-UV endo and T4-endoV was inefficient in mononucleosomes compared with naked DNA. However, the human nucleosome remodeling complex, hSWI/SNF, promoted more homogeneous repair by ML-UV endo and T4-endo V in reconstituted nucleosomes. This result suggests that recognition of DNA damage could be facilitated by a fluid state of the chromatin resulting from chromatin remodeling activities. 相似文献