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141.
Xylitol production by <Emphasis Type="Italic">Candida tropicalis</Emphasis> in a chemically defined medium 总被引:2,自引:0,他引:2
A chemically defined medium that included urea (5 g l(-1)) as a nitrogen source and various vitamins was substituted for a complex medium containing yeast extract (10 g l(-1)) in the production of xylitol by Candida tropicalis. In a fed-batch culture with the chemically defined medium, 237 g xylitol l(-1) was produced from 270 g xylose l(-1) after 120 h. The volumetric rate of xylitol production and the xylitol yield from xylose were 2 g l(-1) h(-1) and 89%, respectively. These values were about 5% lower and 4% higher, respectively, than those obtained using the complex medium. These results indicate that xylitol can be produced effectively in a chemically defined medium. 相似文献
142.
Lane M Maybach JM Hooper K Hasler JF Gardner DK 《Molecular reproduction and development》2003,64(1):70-78
Recombinant albumin can be used to supplement culture medium for the maturation and fertilization of bovine oocytes and subsequent embryo development to the blastocyst stage. Recombinant albumin was able to support blastocyst development at rates equivalent to that of bovine serum albumin (BSA) supplemented media. Supplementation of media containing recombinant albumin and citrate stimulated blastocyst expansion. Culture with recombinant albumin and citrate significantly increased the ability of the resultant blastocysts to re-expand and hatch following cryopreservation. The further addition of the glycosaminoglycan hyaluronan to the culture medium containing either BSA or recombinant albumin also increased the ability of blastocysts to survive cryopreservation. Inclusion of recombinant albumin and hyaluronan in culture media facilitates the development of physiological defined culture conditions. For bovine embryos this has implications for both research and commercial applications where defined reproducible conditions are desirable. 相似文献
143.
Improved generation of C57BL/6J mouse embryonic stem cells in a defined serum-free media 总被引:5,自引:0,他引:5
Cheng J Dutra A Takesono A Garrett-Beal L Schwartzberg PL 《Genesis (New York, N.Y. : 2000)》2004,39(2):100-104
C57BL/6 is a well-characterized mouse strain that is used extensively for immunological and neurological research. The establishment of C57BL/6 ES cell lines has facilitated the study of gene-altered mice in a pure genetic background-however, relatively few such lines exist. Using a defined media supplement, knockout serum replacement (KSR) with knockout DMEM (KSR-KDMEM), we find that we can readily establish ES cell lines from blastocysts of C57BL/6J mice. Six lines were established, all of which were karyotypically normal and could be maintained in the undifferentiated state on mouse embryonic fibroblast (MEF) feeders. One line was further tested and found to be karyotypically stable and germline competent, both prior to manipulation and after gene targeting. For this cell line, efficiencies of cell cloning and chimera generation were greater when maintained in KSR-KDMEM. Our work suggests that the use of defined serum-free media may facilitate the generation of ES cells from inbred mouse strains. 相似文献
144.
AIMS: To analyse the exopolysaccharide (EPS) production by Lactobacillus helveticus ATCC 15807 in a chemically defined medium (CDM) and the effect of nutrients and stress culture conditions on cell growth and EPS formation. METHODS AND RESULTS: Cultures were conducted in CDM: (i) containing essential and nonessential bases and vitamins; (ii) without nonessential bases and vitamins [Simplified CDM (SCDM)]; (iii) SCDM supplemented individually with vitamins and bases. The influence of carbohydrates, pH and osmotic culture conditions on growth and polymer formation was analysed. Adenine and lactose stimulated both growth and EPS production. Constant pH fermentations (4.5 and 6.2) did not improve EPS synthesis while NaCl and glycerol were detrimental for growth and polymer formation. In all media the EPS monomer composition was glucose and galactose (2.5 : 1). CONCLUSIONS: A SCDM containing adenine and lactose was optimal for cell growth and EPS formation by Lact. helveticus ATCC 15807. Controlled pH (6.2 and 4.5) and osmotic stress culture conditions did not improve polymer production. The EPS characteristics were identical in all media. SIGNIFICANCE AND IMPACT OF THE STUDY: This work provides a better knowledge on EPS synthesis by Lact. helveticus. A CDM to perform regulation studies on EPS production by Lact. helveticus species is now available. 相似文献
145.
Two chemically defined media based on xylem fluid chemistry were developed for Xylella fastidiosa. These media were tested and compared to chemically defined media XDM2, XDM4 and XF-26. New media were evaluated for the Pierce's disease (PD) strain UCLA-PD. Our media either was similar to the concentration of some amino acids found in the xylem fluid of the PD-susceptible Vitis vinifera cv. Chardonnay (medium CHARD2) or incorporated the tripeptide glutathione found in xylem fluid composition (medium 3G10-R). CHARD2 and 3G10-R are among the simplest chemically defined media available. Xylem fluid chemistry-based media supported X. fastidiosa growth and especially stimulated aggregation and biofilm formation. 相似文献
146.
J.P. Guyot 《FEMS microbiology letters》1986,34(2):149-153
Abstract Different methanogenic defined mixed cultures, including Cellulomonas sp. strain ATCC21399 as a hydrolytic and fermentative bacterium, were used to show that methane production could proceed from larchwood xylan as well as from cellulose. Via the different mixtures of bacteria used, the role of formate is described. It is shown that formate inhibits methanogenesis from acetate by pure cultures of aceticlastic methanogens. 相似文献
147.
Joanne T. Emerman Eveline E. Fiedler Anthony W. Tolcher Patricia M. Rebbeck 《In vitro cellular & developmental biology. Plant》1987,23(2):134-140
Summary We compared the effects of defined medium, fetal bovine serum (FBS) and human serum (HuS) on the growth and responses to chemotherapeutic
agents of human breast cancer cells in primary culture. Normal and tumor tissues were dissociated to small aggregates and
single cells and seeded onto collagen-gel-coated wells in defined medium or medium supplemented with 5% FBS or 5% HuS. In
all cases examined, defined medium and medium containing HuS were superior to medium containing FBS in supporting growth of
both normal and tumor cell cultures. However, cultures in defined medium showed an initial cell loss. Cells from the same
tumor cultured in different media varied in their responses to chemotherapeutic agents. In light of these results, medium
supplemented with HuS, which promoted attachment of these cells in culture and stimulated their growth, should be the most
appropriate nutrient environment for determining the effects of therapeutic agents on cells as it most closely resembles the
in vivo situation. Because there were also variations in growth rates and chemosensitivities of tumor cells cultured in different
human serum samples, we suggest that optimal conditions in which to culture these cells include the serum of the patient whose
tumor is removed. This serum may provide host factors that influence cell growth and interact with exogenous factors.
This work was supported by a grant from the National Cancer Institute of Canada and funds contributed by Mr. B. T. Wharton
in memory of his wife, Nadia. J. T. Emerman is a research scholar of the National Cancer Institute of Canada. 相似文献
148.
Riekje Biermann Laura Rösner Lisa-Marie Beyer Laura Niemeyer Sascha Beutel 《Engineering in Life Science》2023,23(10):e2300210
Bacillus coagulans is a promising probiotic, because it combines probiotic properties of Lactobacillus and the ability of Bacillus to form endospores. Due to this hybrid relationship, cultivation of this organism is challenging. As the probiotics market continues to grow, there is a new focus on the production of these microorganisms. In this work, a strain-specific bioprocess for B. coagulans was developed to support growth on one hand and ensure sporulation on the other hand. This circumstance is not trivial, since these two metabolic states are contrary. The developed bioprocess uses a modified chemically defined medium which was further investigated in a one-factor-at-a-time assay after adaptation. A transfer from the shake flask to the bioreactor was successfully demonstrated in the scope of this work. The investigated process parameters included temperature, agitation and pH-control. Especially the pH-control improved the sporulation in the bioreactor when compared to shake flasks. The bioprocess resulted in a sporulation efficiency of 80%–90%. This corresponds to a sevenfold increase in sporulation efficiency due to a transfer to the bioreactor with pH-control. Additionally, a design of experiment (DoE) was conducted to test the robustness of the bioprocess. This experiment validated the beforementioned sporulation efficiency for the developed bioprocess. Afterwards the bioprocess was then scaled up from a 1 L scale to a 10 L bioreactor scale. A comparable sporulation efficiency of 80% as in the small scale was achieved. The developed bioprocess facilitates the upscaling and application to an industrial scale, and can thus help meet the increasing market for probiotics. 相似文献
149.
The developmental profile of opioid receptors was studied in rat and guinea pig striatum and hippocampus. The two brain regions show different receptor profiles during development, which are characteristic for each animal. Yet, both tissues and animal species share one common feature; the binding of the universal opioid ligand [3H]diprenorphine per milligram of protein is high at the early embryonic period, it decreases toward birth, and then gradually increases to the adult levels. This apparent transient expression of the receptors during the early developmental stage was manifested in the guinea pig as an actual decrease in the total receptor number. As an attempt to characterize the receptors involved in this process, the binding of the selective mu-opioid ligand [3H]Tyr-D-Ala-Gly-MePhe-NH(CH2)OH [( 3H]DAGO) was studied in striatal membranes of young (P1) and adult (P60) rats. Competition between [3H]DAGO and the delta-selective peptide Tyr-D-Pen-Gly-Phe-D-Pen (DPDPE) shows higher affinity of the delta opioid to P1 membranes than to P60 membranes, though the number of delta receptors in P1 membranes is very small. This observation is in line with a previous study suggesting that opioid receptors in embryonic striatum and hippocampus are less selective to various opioids than those of adult brain. An additional difference between adult and embryonic tissue was observed on Scatchard analysis of [3H]DAGO binding; striatum P60 membranes exhibit one binding site with a KD of 0.8 +/- 0.1 nM and Hill coefficient of 0.96, whereas striatum P1 membranes bind the peptide in an apparent cooperative fashion with an overall Hill coefficient of 1.30.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
150.
Donald J. Sarubbi Ramaswamy Narayanan Nitin T. Telang Michael J. Newman 《In vitro cellular & developmental biology. Plant》1990,26(12):1195-1201
Summary Novel or modified serum-free media were developed for the anchorage-dependent growth of nontransformed murine mammary epithelial
cells (MMEC) and Balb/MK murine keratinocytes respectively. Growth rates for both cell lines were similar in serum-containing
and serum-free media. The serum-free media were used to evaluate potential mechanisms of epithelial cell growth regulation
by type 1 transforming growth factor β(TGF-β1). The growth of MMEC and Balb/ MK cells was reversibly inhibited 40–65% in a
time- and dose-dependent fashion by TGF-β1 under both serum-containing and serum-free conditions. Constitutive over-expression
of a stranfected c-myc oncogene inMMEC did not result in loss of sensitivity to growth inhibition by TGF-β1. In addition, Balb/MK and MMEC growth
inhibition by TGF-β1 was not potentiated by polynsaturated fatty acids or reversed by vitamin E. Expgenous type V collagen
was able to mimic the inhibitory effects of TGF-β1 on the serum-free growth of Balb/MK and MMEC. In contrast, collagen type
I and IV, fibronectin and laminin did not inhibit the growth of these cells. The type V collagen used was not contaminated
with TGF-β, and subsaturating, but not saturating concentrations of type V collagen and TGF-β1 were additive with respect
to Balb/MK and MMEC growth inhibition. These results demonstrate that nontransformed epithelial cell growth inhibition by
TGF-β1 is mediated by mechanisms distinct from those observed with certain carcinoma and melanoma cells. Our results also
suggest the possible involvement of type V collagen in Balb/MK and MMEC growth inhibition by TGF-β1.
This work was supported, in part, by grant #R29 CA 44741 from the National Institutes of Health, Bethesda, MD to NTT. 相似文献