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951.
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953.
Jenni Hammargren Jens Sundström Monika Johansson Per Bergman Carina Knorpp 《Physiologia plantarum》2007,129(1):79-89
The plant nucleoside diphosphate kinase (NDPK, EC 2.7.4.6) gene family consists of three groups whose gene products are found in different subcellular locations. In this study we discuss the evolutionary history, localization and expression of the NDPK genes, addressing the question of functional specialization of the different NDPKs. A phylogenetic analysis revealed that the three NDPK isoforms were present already in the last common ancestor of vascular plants and mosses. Our data also imply that the NDPK3 genes possess a higher degree of conservation than the NDPK1 and NDPK2 genes. The expression levels of the different NDPKs in Arabidopsis thaliana inflorescences, leaves and roots were evaluated using quantitative PCR as well as in silico methods. This analysis showed that NDPK1 is the most highly expressed NDPK gene in all the studied tissues. NDPK3a has the second highest NDPK expression, while NDPK3b is expressed to a very low extent. However, expression of NDPK3b is elevated in inflorescence tissue. In situ hybridization experiments performed on inflorescences showed NDPK3a expression in actively dividing cells. NDPK3b expression was observed during later stages of flower development, specifically in the tapetum, ovules and petals. Additionally, we show that an NDPK3 protein is able to direct the green fluorescent protein to both mitochondria and chloroplasts using transient expression in leaf protoplasts. The dual localisation of NDPK3 was confirmed by Western blot, which also demonstrated that the majority of the NDPK3 protein is found in the mitochondria. 相似文献
954.
Robert Steinfeld Jens C Fuhrmann Jutta G?rtner 《The journal of histochemistry and cytochemistry》2006,54(9):991-996
Tripeptidyl peptidase I (TPP-I) is a lysosomal peptidase with unclear physiological function. TPP-I deficiency is associated with late-infantile neuronal ceroid lipofuscinosis (NCL), a fatal neurodegenerative disease of childhood that is characterized by loss of neurons and photoreceptor cells. We have developed two novel fluorogenic substrates, [Ala-Ala-Phe]2-rhodamine 110 and [Arg-Nle-Nle]2-rhodamine 110, that are cleaved by TPP-I in living cells. Fluorescence of liberated rhodamine 110 was detected by flow cytometry and was dependent on the level of TPP-I expression. Rhodamine-related fluorescence could be suppressed by preincubation with a specific inhibitor of TPP-I. When investigated by fluorescent confocal microscopy, rhodamine signals colocalized with lysosomal markers. Thus, cleavage of these rhodamide-derived substrates is a marker for mature enzymatically active TPP-I. In addition, TPP-I-induced cleavage of [Ala-Ala-Phe]2-rhodamine 110 could be visualized in primary neurons. We conclude that [Ala-Ala-Phe]2-rhodamine 110 and [Arg-Nle-Nle]2-rhodamine 110 are specific substrates for determining TPP-I activity and intracellular localization in living cells. Further, these substrates could be a valuable tool for studying the neuronal pathology underlying classical late-infantile NCL. This article contains online supplemental material at http://www.jhc.org. Please visit this article online to view these materials. 相似文献
955.
The study of genome rearrangements is an important tool in comparative genomics. This paper revisits the problem of sorting a multichromosomal genome by translocations, i.e., exchanges of chromosome ends. We give an elementary proof of the formula for computing the translocation distance in linear time, and we give a new algorithm for sorting by translocations, correcting an error in a previous algorithm by Hannenhalli. 相似文献
956.
Kent Sahlin Jens Steen Nielsen Martin Mogensen Michail Tonkonogi 《Journal of applied physiology》2006,101(3):833-839
Repeated static contractions (RSC) induce large fluctuations in tissue oxygen tension and increase the generation of reactive oxygen species (ROS). This study investigated the effect of RSC on muscle contractility, mitochondrial respiratory function, and in vitro sarcoplasmic reticulum (SR) Ca(2+) kinetics in human muscle. Ten male subjects performed five bouts of static knee extension with 10-min rest in between. Each bout of RSC (target torque 66% of maximal voluntary contraction torque) was maintained to fatigue. Muscle biopsies were taken preexercise and 0.3 and 24 h postexercise from vastus lateralis. Mitochondria were isolated and respiratory function measured after incubation with H(2)O(2) (HPX) or control medium (Con). Mitochondrial function was not affected by RSC during Con. However, RSC exacerbated mitochondrial dysfunction during HPX, resulting in decreased respiratory control index, decreased mitochondrial efficiency (phosphorylated ADP-to-oxygen consumed ratio), and increased noncoupled respiration (HPX/Con post- vs. preexercise). SR Ca(2+) uptake rate was lower 0.3 vs. 24 h postexercise, whereas SR Ca(2+) release rate was unchanged. RSC resulted in long-lasting changes in muscle contractility, including reduced maximal torque, low-frequency fatigue, and faster torque relaxation. It is concluded that RSC increases mitochondrial vulnerability toward ROS, reduces SR Ca(2+) uptake rate, and causes low-frequency fatigue. Although conclusive evidence is lacking, we suggest that these changes are related to increased formation of ROS during RSC. 相似文献
957.
Veit J Erpenbeck Rudolf A J?rres Marc Discher Harald Krentel Dimitrios Tsikas Birgit Luettig Norbert Krug Jens M Hohlfeld 《Nitric oxide》2005,13(2):125-133
Nitric oxide (NO) levels are increased in the exhaled air of asthmatics. As NO levels correlate with allergic airway inflammation, NO measurement has been suggested for disease monitoring. In patients with asthma, we previously demonstrated that intrabronchial treatment with a natural porcine surfactant enhanced airway inflammation after segmental allergen provocation. We studied whether local levels of NO reflect the degree of allergic airway inflammation following segmental allergen challenge with or without surfactant pretreatment. Segmental NO, as well as nitrite and nitrate in bronchoalveolar lavage (BAL) fluid, was measured before and after segmental challenge with either saline, saline plus allergen, or surfactant plus allergen in 16 patients with asthma and five healthy subjects. The data were compared with inflammatory BAL cells. Segmental NO levels were increased after instillation of saline (p < 0.05), or surfactant plus allergen in asthmatics (p < 0.05), and values were higher after surfactant plus allergen compared to saline challenge. Nitrate BAL levels were not altered after saline challenge but increased after allergen challenge (p < 0.05) and further raised by surfactant (p < 0.05), whereas nitrite levels were not altered by any treatment. Segmental NO and nitrate levels correlated with the degree of eosinophilic airway inflammation, and nitrate levels also correlated with neutrophil and lymphocyte numbers in BAL. In healthy subjects, NO, nitrite, and nitrate were unaffected. Thus, segmental NO and nitrate levels reflect the degree of allergic airway inflammation in patients with asthma. Measurement of both markers can be useful in studies using segmental allergen provocation, to assess local effects of potential immunomodulators. 相似文献
958.
959.
Antibacterial activity of marine-derived fungi 总被引:4,自引:0,他引:4
Christophersen Carsten Crescente Oscar Frisvad Jens C. Gram Lone Nielsen Joan Nielsen Per Halfdan Rahbæk Lisa 《Mycopathologia》1998,143(3):135-138
A total of 227 marine isolates of ubiqituous fungi were cultivated on different media and the secondary metabolite content
of the extracts (ethyl acetate/chloroform/methanol 3 : 2 : 1) characterized by HPLC. The fungi were secured from animals,
plants and sediments of Venezuelan waters (0–10 m) including mangroves and lagoonal areas. The extracts were tested for antibacterial
activity. A total of 7 were active towards Vibrio parahaemolyticus and 55 towards Staphylococcus aureus, representing 18 different
fungal species from 8 ascomycetous genera. For 61 strains of Penicillium citrinum antibacterial activity correlated well with
content of secondary metabolites as measured by HPLC. Thirteen isolates of Penicillium steckii produced very similar profiles
of secondary metabolites and 6 of these had activity against either V. parahaemolyticus or S. aureus or both.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
960.
Cloning and characterization of fiber type-specific ryanodine receptor isoforms in skeletal muscles of fish 总被引:2,自引:0,他引:2
Franck Jens P.C.; Morrissette Jeffery; Keen John E.; Londraville Richard L.; Beamsley Mark; Block Barbara A. 《American journal of physiology. Cell physiology》1998,275(2):C401
We have cloned agroup of cDNAs that encodes the skeletal ryanodine receptor isoform(RyR1) of fish from a blue marlin extraocular muscle library. The cDNAsencode a protein of 5,081 amino acids with a calculated molecular massof 576,302 Da. The deduced amino acid sequence shows strong sequenceidentity to previously characterized RyR1 isoforms. An RNA probederived from a clone of the full-length marlin RyR1 isoform hybridizesto RNA preparations from extraocular muscle and slow-twitch skeletalmuscle but not to RNA preparations from fast-twitch skeletal or cardiacmuscle. We have also isolated a partial RyR clone from marlin andtoadfish fast-twitch muscles that shares 80% sequence identity withthe corresponding region of the full-length RyR1 isoform, and a RNAprobe derived from this clone hybridizes to RNA preparations fromfast-twitch muscle but not to slow-twitch muscle preparations. Westernblot analysis of slow-twitch muscles in fish indicates the presence ofonly a single high-molecular-mass RyR proteincorresponding to RyR1. [3H]ryanodine bindingassays revealed the fish slow-twitch muscle RyR1 had a greatersensitivity for Ca2+ than thefast-twitch muscle RyR1. The results indicate that, in fish muscle,fiber type-specific RyR1 isoforms are expressed and the two proteinsare physiologically distinct. 相似文献