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31.
Characterization of two CTR-like protein kinases in Rosa hybrida and their expression during flower senescence and in response to ethylene 总被引:4,自引:0,他引:4
Müller R Owen CA Xue ZT Welander M Stummann BM 《Journal of experimental botany》2002,53(371):1223-1225
The expression of two CTR-gene homologues was investigated during flower senescence in two Rosa hybrida cultivars. A fragment of a gene for a protein kinase, termed RhCTR1 (GenBank Acc. No. AF271206), was amplified by PCR and used to isolate the corresponding full-length cDNA (Acc. No. AY032953) from a rose petal cDNA library. The protein RhCTR1 has 66% amino acid identity to Arabidopsis CTR1. A fragment of a second CTR homologue, termed RhCTR2 (Acc. No. AY029067) is 69% identical to the corresponding region of RhCTR1. RhCTR1 expression increased during flower senescence, while RhCTR2 was constitutively expressed during flower development. The expression of both RhCTR1 and RhCTR2 was increased in response to exogenous ethylene. 相似文献
32.
Johan Petersson Alejandro Sánchez-Crespo Stig A Larsson Margareta Mure 《Journal of applied physiology》2007,102(1):468-476
Emission tomography provides three-dimensional, quantitative images of the distribution of radiotracers used to mark physiological, metabolic, or pathological processes. Quantitative single photon emission computed tomography (SPECT) requires correction for the image-degrading effects due to photon attenuation and scatter. Phantom experiments have shown that radioactive concentrations can be assessed within some percentage of the true value when relevant corrections are applied. SPECT is widely spread, and radiotracers are available that are easy to use and comparably inexpensive. Compared with other methods, SPECT suffers from a lower spatial resolution, and the time required for image acquisition is longer than for some alternative methods. In contrast to some other methods, SPECT allows simultaneous imaging of more than one process, e.g., both regional blood flow and ventilation, for the whole lung. SPECT has been used to explore the influence of posture and clinical interventions on the spatial distribution of lung blood flow and ventilation. Lung blood flow is typically imaged using macroaggregates of albumin. Both radioactive gases and particulate aerosols labeled with radioactivity have been used for imaging of regional ventilation. However, all radiotracers are not equally suited for quantitative measurements; all have specific advantages and limitations. With SPECT, both blood flow and ventilation can be marked with radiotracers that remain fixed in the lung tissue, which allows tracer administration during conditions different from those at image registration. All SPECT methods have specific features that result from the used radiotracer, the manner in which it is administered, and how images are registered and analyzed. 相似文献
33.
Cytochrome c oxidase is a superfamily of membrane bound enzymes catalyzing the exergonic reduction of molecular oxygen to water, producing an electrochemical gradient across the membrane. The gradient is formed both by the electrogenic chemistry, taking electrons and protons from opposite sides of the membrane, and by proton pumping across the entire membrane. In the most efficient subfamily, the A-family of oxidases, one proton is pumped in each reduction step, which is surprising considering the fact that two of the reduction steps most likely are only weakly exergonic. Based on a combination of quantum chemical calculations and experimental information, it is here shown that from both a thermodynamic and a kinetic point of view, it should be possible to pump one proton per electron also with such an uneven distribution of the free energy release over the reduction steps, at least up to half the maximum gradient. A previously suggested pumping mechanism is developed further to suggest a reason for the use of two proton transfer channels in the A-family. Since the rate of proton transfer to the binuclear center through the D-channel is redox dependent, it might become too slow for the steps with low exergonicity. Therefore, a second channel, the K-channel, where the rate is redox-independent is needed. A redox-dependent leakage possibility is also suggested, which might be important for efficient energy conservation at a high gradient. A mechanism for the variation in proton pumping stoichiometry over the different subfamilies of cytochrome oxidase is also suggested. This article is part of a Special Issue entitled: 18th European Bioenergetic Conference. 相似文献
34.
Britt-Marie Swahn David Wensbo Johan Sandell Daniel Sohn Can Slivo David Pyring Jonas Malmström Erwan Arzel Michaela Vallin Margareta Bergh Fredrik Jeppsson Allan E. Johnson Anders Juréus Jan Neelissen Samuel Svensson 《Bioorganic & medicinal chemistry letters》2010,20(6):1976-1980
The syntheses and SAR of new series of β-amyloid binding agents are reported. The effort to optimize signal-to-background ratios for these ligands are described. Compounds 8, 21 and 30 displayed desirable lipophilicity and pharmacokinetic properties. Compounds 8 and 21 were evaluated with in vitro autoradiographic studies and in vivo in APP/PS1 transgenic mice. It is shown that it was possible to increase the signal-to-background ratios compared to PIB 1, as demonstrated by compounds 8 and 21. 相似文献
35.
Hans von Stedingk Per Rydberg Margareta Törnqvist 《Journal of chromatography. B, Analytical technologies in the biomedical and life sciences》2010,878(27):2483-2490
A rapid and sensitive method using liquid chromatography–tandem mass spectrometry (LC–MS/MS) for simultaneous determination of adducts from acrylamide, glycidamide and ethylene oxide to N-terminal valines in hemoglobin (Hb) was developed. This new procedure is based on the same principles as the N-alkyl Edman procedure for analysis of adducts from electrophilic agents to N-terminal valines in Hb. The N-substituted valines can be detached, enriched and measured selectively as thiohydantoins by the use of an Edman reagent, in this case fluorescein isothiocyanate (FITC). This procedure is denoted as the “adduct FIRE procedure” as the FITC reagent is used for measurement of adducts (R) formed from electrophilic compounds with a modified Edman procedure. In this study, fluorescein thiohydantoin (FTH) analytes of N-substituted valines from acrylamide, glycidamide and ethylene oxide, as well as their corresponding hepta- and tri-deuterium-substituted analogues, were synthesized. These analytes (n = 8) were then characterized by LC–MS/MS (ESI, positive ion mode) and obtained product ions were interpreted. A considerable work with optimization of the FIRE procedure™, resulted in a procedure in which low background levels of the studied adducts could be measured from 250 μL lyzed whole blood samples (human non-smokers). The analytes were enriched and purified with solid phase extraction columns and analyzed by LC–MS/MS with LOQ down to 1 pmol adduct/g Hb. Compared to other procedures for determination of N-terminal Hb adducts, the introduction of FITC has led to a simplified procedure, where whole blood also can be used, giving new opportunities and reduced hand on time with increased sample throughput. 相似文献
36.
Tileye Feyissa Li-Hua Zhu Legesse Negash Margareta Welander 《Plant Cell, Tissue and Organ Culture》2007,88(3):277-288
The effects of growth regulators, wounding and antibiotics on regeneration of Hagenia abyssinica were investigated and the rolB gene was introduced into this species by Agrobacterium-mediated transformation. Regeneration was affected by type of growth regulators, wounding and antibiotics. Up to 100% regeneration
could be obtained. Three transformed clones (T1, T2.1, T2.2), confirmed by PCR and Southern blot, were obtained only by excluding
kanamycin from the selection medium 6 weeks after culture, followed by selection during shoot multiplication. RT-PCR revealed
strong expression of rolB gene in shoots and roots of all the transgenic clones, but from leaf samples, it was detected only in T1. Rooting frequency
was 77% (T1), 50% (T2.1), 57% (T2.2) and 0% for control shoots on growth regulator-free rooting medium. 相似文献
37.
After activation, most G protein-coupled receptors (GPCRs) are regulated by a cascade of events involving desensitization and endocytosis. Internalized receptors can then be recycled to the plasma membrane, retained in an endosomal compartment, or targeted for degradation. The GPCR-associated sorting protein, GASP, has been shown to preferentially sort a number of native GPCRs to the lysosome for degradation after endocytosis. Here we show that a mutant beta(2) adrenergic receptor and a mutant mu opioid receptor that have previously been described as lacking "recycling signals" due to mutations in their C termini in fact bind to GASP and are targeted for degradation. We also show that a mutant dopamine D1 receptor, which has likewise been described as lacking a recycling signal, does not bind to GASP and is therefore not targeted for degradation. Together, these results indicate that alteration of receptors in their C termini can expose determinants with affinity for GASP binding and consequently target receptors for degradation. 相似文献
38.
In this study we examined an influence of leg extensor strength qualities on agility performance in a latent space. Male physical education students (N = 168) were tested with three standard agility performance tests (lateral stepping, 20-yard shuttle run, and slalom run). Nine measures of leg extensor strength qualities including explosive strength, elastic strength, and maximal strength, were also assessed. As expected, factor analysis of all tests revealed four relatively independent factors: explosive strength, elastic strength, agility, and maximal strength. All three extracted strength factors were included into a regression analysis as predictors to evaluate their influence of the agility factor (i.e. criterion). Although the regression analysis revealed significant multiple correlation between predictors and the criterion (R = 0.41; p < 0.001), the amount of explained variance of agility performance by the strength factors was rather low (17%). We conclude that the leg extensor strength qualities are poor predictors of agility performance in physically active men. 相似文献
39.
Adventitious root formation in Malus ‘Jork 9’ stem discs was studied through temporarily blocking DNA synthesis by application
of aphidicolin (AD). Higher number of roots per disc (8.4) after 21 days of cultivation were formed after a 24-h pulse of
15 μM AD, compared to control without AD application (6.7), with significantly more roots (3.7) already appearing at day 7,
compared to 1.5 roots on the control. The promotive effect of AD on rooting was lower at 5 μM, while a concentration of 30 μM
was slightly inhibitory. Results show that DNA synthesis is effectively blocked by AD, and this blockage is overcome after
AD withdrawal. The data indicate that AD treatment influences cell divisions, thereby, might synchronise root initiation.
The effects of different treatments with and without AD were studied at the cellular level by visualising DNA replication
through BrdU-labelling. BrdU labelling further revealed temporal changes in the competence of the explants to respond to applied
IBA. Thus, it is shown that the proportion of replicating nuclei present during 28–32 h is significantly increased in the
split IBA treatment (0–4 h and 28–32 h; treatment C3), compared with a single IBA application during 0–8 h (treatment C3.1).
An erratum to this article can be found at 相似文献
40.
Pheochromocytomas and sympathetic paragangliomas are rare tumours arising from chromaffin cells, producing catecholamines in various amounts. Fatal hypertensive episodes may occur perioperatively, which are preventable by alpha adrenergic receptor blockers. The perioperative mortality rate of diagnosed versus undiagnosed catecholamine-producing tumours is significant, considering that only a minority of tumours develop metastasis. Herein we describe a case of a primary adrenal pheochromocytoma referred to as a pancreatic tumour, successfully diagnosed by endoscopic ultrasound-guided fine needle aspiration biopsy, with a distinct morphology (prominent nuclear anisonucleosis, intranuclear pseudoinclusions, and multinucleation) and immunohistochemical signature. 相似文献