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51.
52.
Joseline Ratnam Barbara Zdrazil Daniela Digles Emiliano Cuadrado-Rodriguez Jean-Marc Neefs Hannah Tipney Ronald Siebes Andra Waagmeester Glyn Bradley Chau Han Chau Lars Richter Jose Brea Chris T. Evelo Edgar Jacoby Stefan Senger Maria Isabel Loza Gerhard F. Ecker Christine Chichester 《PloS one》2014,9(12)
53.
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Two Systems for Concentrating CO(2) and Bicarbonate during Photosynthesis by Scenedesmus 总被引:5,自引:3,他引:2 下载免费PDF全文
Scenedesmus cells grown on high CO2, when adapted to air levels of CO2 for 4 to 6 hours in the light, formed two concentrating processes for dissolved inorganic carbon: one for utilizing CO2 from medium of pH 5 to 8 and one for bicarbonate accumulation from medium of pH 7 to 11. Similar results were obtained with assays by photosynthetic O2 evolution or by accumulation of dissolved inorganic carbon inside the cells. The CO2 pump with K0.5 for O2 evolution of less than 5 micromolar CO2 was similar to that previously studied with other green algae such as Chlamydomonas and was accompanied by plasmalemma carbonic anhydrase formation. The HCO3− concentrating process between pH 8 to 10 lowered the K0.5 (DIC) from 7300 micromolar HCO3− in high CO2 grown Scenedesmus to 10 micromolar in air-adapted cells. The HCO3− pump was inhibited by vanadate (Ki of 150 micromolar), as if it involved an ATPase linked HCO3− transporter. The CO2 pump was formed on low CO2 by high-CO2 grown cells in growth medium within 4 to 6 hours in the light. The alkaline HCO3− pump was partially activated on low CO2 within 2 hours in the light or after 8 hours in the dark. Full activation of the HCO3− pump at pH 9 had requirements similar to the activation of the CO2 pump. Air-grown or air-adapted cells at pH 7.2 or 9 accumulated in one minute 1 to 2 millimolar inorganic carbon in the light or 0.44 millimolar in the dark from 150 micromolar in the media, whereas CO2-grown cells did not accumulate inorganic carbon. A general scheme for concentrating dissolved inorganic carbon by unicellular green algae utilizes a vanadate-sensitive transporter at the chloroplast envelope for the CO2 pump and in some algae an additional vanadate-sensitive plasmalemma HCO3− transporter for a HCO3− pump. 相似文献
55.
Relationship of scrotal surface temperature measured by infrared thermography to subcutaneous and deep testicular temperature in the ram 总被引:2,自引:0,他引:2
The right testis of 9 anaesthetized rams was removed from the parietal tunica vaginalis and replaced by a surrogate testis (water-filled balloon) through which water of known temperature was circulated. Thermistors were inserted in the surrogate testis, between the scrotal skin and parietal tunica vaginalis on the right side, and deep within the intact left testis. Scrotal surface temperatures over the surrogate and intact testes were measured by infrared thermography. Scrotal surface temperature was correlated (P less than 0.01) with both subcutaneous (r = 0.95) and surrogate (r = 0.91) testicular temperature. The temperature differential between scrotal surface (30.1 +/- 0.1 degrees C) and deep testicular temperature over the intact side (34.9 +/- 0.09 degrees C) was 4.8 degrees C at an ambient temperature between 24.0 and 26.6 degrees C. Contact with the scrotal skin is not required to measure scrotal surface temperature by infrared thermography. This, coupled with the close association between scrotal surface temperature and that of underlying structures, will enhance our ability to understand better testicular temperature regulation and scrotal/testicular function. 相似文献
56.
Goring DR Banks P Fallis L Baszczynski CL Beversdorf WD Rothstein SJ 《The Plant journal : for cell and molecular biology》1992,2(6):999-1003
We have previously described a developmentally regulated mRNA in maize that accumulates in mature embryos and is involved in a variety of stress responses in the plant. The sequence of the encoded 16 kDa protein (MA16) predicts that it is an RNA-binding protein, since it possesses a ribonucleoprotein consensus sequence-type RNA-binding domain (CS-RBD). To assess the predicted RNA binding property of the protein and as a starting point to characterize its function we have used ribohomopolymer-binding assays. Here we show that the MA16-encoded protein binds preferentially to uridine- and guanosine-rich RNAs. In light of these results a likely role for this protein in RNA metabolism during late embryogenesis and in the stress response is discussed. 相似文献
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58.
Rapid Retrograde Tyrosine Phosphorylation of
trkA and Other Proteins in Rat
Sympathetic Neurons in Compartmented Cultures 总被引:12,自引:0,他引:12 下载免费PDF全文
According to the current theory of retrograde signaling, NGF binds to receptors on the axon terminals and is internalized by receptor-mediated endocytosis. Vesicles with NGF in their lumina, activating receptors in their membranes, travel to the cell bodies and initiate signaling cascades that reach the nucleus. This theory predicts that the retrograde appearance of activated signaling molecules in the cell bodies should coincide with the retrograde appearance of the NGF that initiated the signals. However, we observed that NGF applied locally to distal axons of rat sympathetic neurons in compartmented cultures produced increased tyrosine phosphorylation of trkA in cell bodies/ proximal axons within 1 min. Other proximal proteins, including several apparently localized in cell bodies, displayed increased tyrosine phosphorylation within 5–15 min. However, no detectable 125I-NGF appeared in the cell bodies/proximal axons within 30–60 min of its addition to distal axons. Even if a small, undetectable fraction of transported 125I-NGF was internalized and loaded onto the retrograde transport system immediately after NGF application, at least 3–6 min would be required for the NGF that binds to receptors on distal axons just outside the barrier to be transported to the proximal axons just inside the barrier. Moreover, it is unlikely that the tiny fraction of distal axon trk receptors located near the barrier alone could produce a measurable retrograde trk phosphorylation even if enough time was allowed for internalization and transport of these receptors. Thus, our results provide strong evidence that NGF-induced retrograde signals precede the arrival of endocytotic vesicles containing the NGF that induced them. We further suggest that at least some components of the retrograde signal are carried by a propagation mechanism. 相似文献
59.
In contrast to the wild type strain of Scenedesmus , mutant C-6E synthesized only trace amounts of the carotenoids violaxanthin and lutein during prolonged heterotrophic growth. All other carotenoids and carotenoid precursors, such as phytoene, were undetectable. Additionally, only reduced levels of chlorophyll a and no chlorophyll b were formed. To evaluate the potential site of inhibition in the pathway for carotenoid biosynthesis the enzymatic activities of geranylgeranyl pyrophosphate synthase and phytoene synthase were assayed in cell-free extracts. Both enzymes were highly active in extracts of the wild type but only geranylgeranyl pyrophosphate synthase was active in comparable extracts from mutant C-6E . This observation strongly indicates that the phenotype of C-6E results from either a mutation of the phytoene synthase structural gene or of a regulatory gene involved in expression of this enzyme. Other phenotypic effects on composition and structure of the photosynthetic apparatus are discussed as a secondary consequence of the carotenoid deficiency in the thylakoid membranes. 相似文献
60.
Interstitial deletion of chromosome 6q: Precise definition of the breakpoints by microdissection,DNA amplification,and reverse painting 总被引:3,自引:0,他引:3
N. Rubtsov G. Senger A. Neumann C. Kelbova K. Junker V. Beensen U. Claussen N. Rubtsov H. Kuzcera 《Human genetics》1996,97(6):705-709
Routine chromosomal analysis using GTG-banding alone showed a mosaic terminal deletion of 6q in a 14-week-old boy with developmental
retardation, facial anomalies, agenesis of corpus callosum, cleft palate, hypotonia, short neck and pterygium colli, and minor
anomalies of hands and feet. Discrepancies between the clinical findings on our patient and those described in the literature
on patients having terminal deletions led to a more precise analysis of the karyotype. Reverse painting was performed on normal
G-banded metaphases for exact determination of the breakpoints and on metaphases of the patient for evaluation of mosaicism.
A DNA library that was obtained by microdissection of three deleted chromosomes 6 was used as a painting probe. Subsequent
DNA amplification was performed with the help of topoisomerase-pretreated degenerate oligonucleotide primers. Unexpectedly,
the hybridization pattern on normal metaphase chromosomes revealed an interstitial deletion with breakpoints at 6q25.1 and
6q27 instead of a terminal deletion. Hybridization on metaphases of the patient showed one deleted chromosome 6 in all metaphases
analyzed at a higher resolution rather than mosaicism as previously assumed [karyotype, 46,XY,del(6)(q25.1→q27)]. We assume
that in the single cases of 6q– described in the literature the deletions are misclassified. This might be due to difficulties in distinguishing between
interstitial and terminal deletions at 6q and in precisely defining chromosomal breakpoints after GTG-banding alone.
Received: 29 November 1995 / Revised: 15 January 1996 相似文献