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91.
Rapid Growth of Acanthamoeba In Defined Media; Induction of Encystment By Glucose-Acetate Starvation 总被引:3,自引:0,他引:3
THOMAS J. BYERS ROBERT A. AKINS BARBARA J. MAYNARD RICHARD A. LEFKEN SCOTT M. MARTIN 《The Journal of eukaryotic microbiology》1980,27(2):216-219
Defined media are described that support 14-20 h generation times for Acanthamoeba castellanii and A. rhysodes in monolayer cultures. the media differ in minor ways from previously described media, but the growth rates are greatly improved over previously reported values. Maximum growth rates were observed for A, castellanii in a complex medium containing 21 amino acids, but near-maximum rates could be achieved in relatively simple media containing 9 amino acids. Growth occurred with 6 amino acids, as reported by others, but generation times exceeded 30 h. Amitosis was a common problem during early subcultures in defined media, but became infrequent after repeated transfers. Synchronous encystment resulting in 70-80% cyst formation could be induced in the defined media by glucose and acetate starvation. the rate of encystment varied with cell density at the time of starvation and was optimal at initial densities of 400-800 amebae/mm2. 相似文献
92.
Richard Holmes Gretchen Mercer Nalini Mohamed 《In vitro cellular & developmental biology. Plant》1979,15(7):522-530
Summary α-Protein growth fraction (AGF) eliminates the 60- to 90-day adaptive phase required to establish actively growing cultures
of HeLa (Gey), human heart (Girardi), KB (Eagle) and other established cell lines in serum-free chemically defined medium
A3. AGF is effective at less than 0.4 μg per ml. By using the procedures described in the text, it is possiblee to culture HeLa
cells is very simple media such as Eagle's basal medium. The properties of AGF are such that it may be adsorbed on glass or
plastic flasks. Glass flasks treated with AGF retain full activity after washing with acetone, and treatment with ethyl ether
and chemically defined medium. Adsorbed AGF is destroyed by trypsin. AGF can detoxify protamines, polylysines or histones.
It will reverse the aggregation response induced by adding complexes composed of carboxymethylcellulose (CMC) and basic proteins.
The results support the contention that highly adsorptive AGF functions at the cell surface and is capable of modifying the
response of the cell to its environment. 相似文献
93.
Expansion of human embryonic stem cells in defined serum-free medium devoid of animal-derived products 总被引:11,自引:0,他引:11
Li Y Powell S Brunette E Lebkowski J Mandalam R 《Biotechnology and bioengineering》2005,91(6):688-698
Human embryonic stem cells (hESCs) can serve as an unlimited cell source for cellular transplantation and tissue engineering due to their prolonged proliferation capacity and their unique ability to differentiate into derivatives of all three-germ layers. In order to reliably and safely produce hESCs, use of reagents that are defined, qualified, and preferably derived from a non-animal source is desirable. Traditionally, mouse embryonic fibroblasts (MEFs) have been used as feeder cells to culture undifferentiated hESCs. We recently reported a scalable feeder-free culture system using medium conditioned by MEFs. The base and conditioned medium (CM) still contain unknown bovine and murine-derived components, respectively. In this study, we report the development of a hESC culture system that utilizes a commercially available serum-free medium (SFM) containing human sourced and recombinant proteins supplemented with recombinant growth factor(s) and does not require conditioning with feeder cells. In this system, which employs human laminin coated surface and high concentration of hbFGF, the hESCs maintained undifferentiated hESC morphology and had a twofold increase in expansion compared to hESCs grown in MEF-CM. The hESCs also expressed surface markers SSEA-4 and Tra-1-60 and maintained expression of hTERT, Oct4, and Cripto genes similar to cells cultured in MEF-CM. In addition, hESCs maintained in this culture system were able to differentiate in vitro and in vivo into cells of all three-germ layers. The cells maintained a normal karyotype after prolonged culture in SFM. In summary, this study demonstrates that the hESCs cultured in defined non-conditioned serum-free medium (NC-SFM) supplemented with growth factor(s) retain the characteristics and replicative potential of hESCs. The use of defined culture system with NC-SFM on human laminin simplifies scale-up and allows for reproducible generation of hESCs under defined and controlled conditions that would serve as a starting material for production of hESC derived cells for therapeutic use. 相似文献
94.
95.
Variable number of pig MHC class I genes in different serologically defined haplotypes identified by a 3'-untranslated region probe 总被引:1,自引:0,他引:1
96.
Karl A. Scheidt William R. Roush James H. McKerrow Paul M. Selzer Elizabeth Hansell Philip J. Rosenthal 《Bioorganic & medicinal chemistry》1998,6(12):2477-2494
The inhibition of cysteine proteases is being studied as a strategy to combat parasitic diseases such as Chagas' disease, leishmaniasis, and malaria. Cruzain is the major cysteine protease of Trypanosoma cruzi, the etiologic agent of Chagas' disease. A crystal structure of cruzain, covalently inactivated by fluoromethyl ketone inhibitor 1 (Cbz-Phe-Ala-FMK), was used as a template to design potential inhibitors. Conformationally constrained γ-lactams containing electrophilic aldehyde (12, 17, 18, 25, 26, and 29) or vinyl sulfone (43, 44, and 46) units were synthesized. Constrained lactam 26 had IC50 values of ca. 20 nM against the Leishmania major protease and ca. 50 nM versus falcipain, an important cysteine protease isolated from Plasmodium falciparum. However, all of the conformationally constrained inhibitors were weak inhibitors of cruzain, compared to unconstrained peptide aldehyde (e.g. 5) and vinyl sulfone inhibitors (e.g. 48, which proved to be an excellent inhibitor of cruzain with an apparent second order inhibition rate constant (kinact/Ki) of 634,000 s−1M−1). A significant reduction in activity was also observed with acyclic inhibitors 30 and 51 containing -methyl phenylalanine residues at the P2 position. These data indicate that the pyrrolidinone ring, especially the quarternary center at P2, interferes with the normal substrate binding mode with cruzain, but not with falcipain or the leishmania protease. 相似文献
97.
Studies on the growth and respiration of batch suspension cultures of rice (Oryza sativa L.) in a reference medium containing Murashige-Skoog salts, 2% (w/v) sucrose and yeast extract are reported. It was found that the yeast extract contributed 70% of the phosphate in this medium, and that the cells grew equally well in continued subculture in a defined medium which contained 6 mM phosphate and 3% (w/v) sucrose and the remaining Murashige-Skoog salts. Cell clumps (up to 1.5 mm diameter) were prevalent in the initial cultures in the reference medium. In such cultures the critical O2 pressure of cell respiration was high (125 M), and ethanol accumulated. When cell clumps were routinely removed during several weekly subcultures on the defined medium cultures were obtained in which no clumps were present, the critical O2 pressures was decreased to 40 M and no ethanol accumulated.This work was supported by grant PCM-84-03542 from the U.S. National Science Foundation. 相似文献
98.
Summary Epithelium from normal human endometrium was cultured as morphologically stable vesicular structures in a defined, hormone-supplemented
PFMR-4 medium. The structures consisted of a single layer of polarized epithelial cells with the apical surface facing the
external culture medium, and the basal surface resting on a well-defined basal lamina adjacent to the internal lumen. Vesicles
were shown to (a) retain their viability for up to 3 mo. in culture, (b) to actively synthesize DNA after being cultured for
over a month in a defined medium, and (c) to respond to steroid hormones. When embedded within a collagen gel, the vesicles
reversed their epithelial polarity and formed branching, pseudoglandular structures. It was concluded that the three-dimensional
shape of the epithelial vesicles had a critical role to play in their morphological stability nutient requirement, and hormone
sensitivity. 相似文献
99.
Plasmodium falciparum: continuous cultivation of erythrocyte stages in plasma-free culture medium 总被引:2,自引:0,他引:2
Continuous in vitro cultivation of the malaria parasite, Plasmodium falciparum, was performed in plasma-free medium. The medium used was standard RPMI 1640 supplemented with adenosine, unsaturated C-18 fatty acids, and fatty acid-free bovine serum albumin. The medium was changed daily and the cultures were diluted with washed erythrocytes twice weekly. Growth was routinely maintained for 1 month at which time the experiments were usually terminated. Although the overall growth rates were consistently lower than in control cultures with plasma, continuous growth occurred in the absence of plasma in cultures containing cis-vaccenic, oleic, and linoleic acids. 相似文献
100.
Han Yueh Ayan Pal Kenneth Chang Mark K. Schlegel Larry W. McLaughlin 《Nucleosides, nucleotides & nucleic acids》2013,32(6):320-332
We herein present the first synthesis and characterization of the two C5′ diastereomers of 8,6′-cyclo-2′,6′-dideoxyadenosine. Starting from commercially available 2′-deoxyadenosine, the target cyclonucleosides were synthesized in 11 linear steps. Following a zinc-mediated cyclization reaction to form the seven-membered ring, the stereochemistry of the newly formed chiral center was established using two-dimensional NOESY NMR experiments. [Supplemental materials are available for this article. Go to the publisher's online edition of Nucleosides, Nucleotides & Nucleic Acids for the free supplemental resource.] 相似文献