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311.
Apoptosis is frequently regulated by different protein kinases including protein kinase C family enzymes. Both inhibitory and stimulatory effects were demonstrated for several of the different PKC isoforms. Here we show that the novel PKC isoform, PKCη, confers protection against apoptosis induced by the DNA damaging agents, UVC irradiation and the anti-cancer drug — Camptothecin, of the breast epithelial adenocarcinoma MCF-7 cells. The induced expression of PKCη in MCF-7 cells, under the control of the tetracycline-responsive promoter, resulted in increased cell survival and inhibition of cleavage of the apoptotic marker PARP-1. Activation of caspase-7 and 9 and the release of cytochrome c were also inhibited by the inducible expression of PKCη. Furthermore, JNK activity, required for apoptosis in MCF-7, as indicated by the inhibition of both caspase-7 cleavage and cytochrome c release from the mitochondria in the presence of the JNK inhibitor SP600125, was also suppressed by PKCη expression. Hence, in contrast to most PKC isoforms enhancing JNK activation, our studies show that PKCη is an anti-apoptotic protein, acting as a negative regulator of JNK activity. Thus, PKCη could represent a target for intervention aimed to reduce resistance to anti-cancer treatments. 相似文献
312.
The effects of dikegulac sodium on plastid RNA syntheses werestudied, as dikegulac induces the formation of yellow misshapenleaves. It depressed uridine incorporation into both plastidand cytoplasmic ribosomal RNAs of axenically cultured Spirodela(duckweed). With short labeling time (1 hr) dikegulac specificallysuppressed the synthesis of a plastid 1.2 ? 106 MW RNA species,as well as nonspecifically depressing incorporation. With longerlabeling time (24 hr), the incorporation into mature plastidrRNAs was suppressed to a greater extent than that into cytoplasmicrRNAs. The inhibitions of uridine incorporation caused by dikegulacare probably indirect and a reflection of its effect on othergrowth parameters. (Received September 25, 1976; ) 相似文献
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314.
Avraham Zeharia Avraham Shaag Orit Pappo Ann Saada Olga Karicheva Noa Ofek Daphna Marom Ivan Tarassov 《American journal of human genetics》2009,85(3):401-407
Acute liver failure in infancy accompanied by lactic acidemia was previously shown to result from mtDNA depletion. We report on 13 unrelated infants who presented with acute liver failure and lactic acidemia with normal mtDNA content. Four died during the acute episodes, and the survivors never had a recurrence. The longest follow-up period was 14 years. Using homozygosity mapping, we identified mutations in the TRMU gene, which encodes a mitochondria-specific tRNA-modifying enzyme, tRNA 5-methylaminomethyl-2-thiouridylate methyltransferase. Accordingly, the 2-thiouridylation levels of the mitochondrial tRNAs were markedly reduced. Given that sulfur is a TRMU substrate and its availability is limited during the neonatal period, we propose that there is a window of time whereby patients with TRMU mutations are at increased risk of developing liver failure. 相似文献
315.
The effect of angiotensin II on myosin heavy chain expression in cultured myocardial cells 总被引:1,自引:0,他引:1
Noa Shalitin Menahem Friedman Hadassa Schlesinger Yael Barhum Maurice J. Levy Wolfgang Schaper Gania Kessler-Icekson 《In vitro cellular & developmental biology. Animal》1996,32(9):573-578
Summary Angiotensin II (AII), the principal mediator of the renin-angiotensin system, is an important regulator of vascular and cardiac
homeostasis. AII has also been shown to be a regulator of cardiac hypertrophy and of the corresponding changes in amount and
composition of certain tissue proteins. We examined the trophic effects of AII on cultured myocytes derived from neonatal
rat ventricles and followed, by Northern blot analysis and polyacrylamide gel electrophoresis, the expression of α- and β-myosin
heavy chain iso-mRNAs and isoproteins. Our findings show that a single administration of AII is sufficient to induce a trophic
response in cultured beating myocytes and to enhance the expression of β-myosin heavy chain iso-mRNA and isoprotein, having
no effect on α-myosin heavy chain. Induction of α-myosin heavy chain expression by thyroid hormone before AII was administered
showed that AII could not potentiate a shift from α- to β-myosin heavy chain predominance. We suggest that the potency of
AII to regulate the expression of myosin heavy chain isogenes is restricted to the β isoform and is overridden by thyroid
hormone. 相似文献
316.
Noa Betzalel Paul Ben Ishai Sharon Einav Yuri Feldman 《Journal of biophotonics》2021,14(7):e202100027
The helical nature of human sweat ducts, combined with the morphological and dielectric properties of skin, suggests electromagnetic activity in the sub-THz frequency band. A detailed electromagnetic simulation model of the skin, with embedded sweat ducts, was created. The model includes realistic dielectric properties based on the measured water content of each layer of skin, derived from Raman Spectroscopy. The model was verified by comparing it to measurements of the reflection coefficient of the palms of 13 volunteers in the frequency band 350–410 GHz. They were subjected to a measurement protocol intended to induce mental stress, thereby also activating the sweat glands. The Galvanic Skin Response was concurrently measured. Using the simulation model the optimal ac-conductivity for each measurement was found. The range of variation for all subjects was found to be from 100 S/m to a maximum value of 6000 S/m with averages of 1000 S/m. These are one order of magnitude increase from the accepted values for water at these frequencies (~100 s/m at 100 GHz). Considering the known biochemical mechanism for inducing perspiration, we conclude that these ac-conductivity levels are probably valid, even though the real time measurements of sweat ac-conductivity levels inside the duct are inaccessible. 相似文献
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The generation of large mutant libraries for in vitro enzyme evolution presents the challenge of effectively screening libraries of 104–107 mutants on the basis of simultaneously assaying their biocatalytic activity. In this review, we highlight the main steps involved in this process, describe the alternative approaches to address this challenge, survey the state-of-the-art technology and assess achievements already made. It is anticipated that, as a result of the expected accomplishment of further improvements in high-throughput screening that will allow routine screening of whole libraries, the number of useful new and improved enzymes derived through in vitro enzyme evolution will expand rapidly in the near future. 相似文献