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101.
The activity of MAO-A and MAO-B in four different brain regions (striatum, limbic system, occipito-temporal cortex and hemispheres) was determined after hemitransection of the left side. There was no difference in the MAO-A activities of either the left or right sides of the brain in either control or hemitransected rats. The activity of MAO-B was the same for both sides in control rats, but there was an increased MAO-B activity in the left side of the hemitransected rats with respect to the right side in all brain regions investigated, with the possible exception of the limbic system. The increase was due to a change in the Vmax rather than to a changed Km of the MAO-B. The interaction of the MAO-B with oxygen was unchanged after hemitransection. 相似文献
102.
The solution conformations of three trispeptides--L,L,L-1,3,5-C6H3[CH2NHCOCH(X)-NHBoc++ +]3, X = CH3 (Ala) or CH2CH(CH3)2 (Leu), and L,L,L-N(CH2CH2NHCOCH[CH2-CH(CH3)2]NHBoc)3--have been determined from their ir and vibrational CD (VCD) spectra in the NH stretching and carbonyl stretching regions in apolar solution. The compounds containing L-Leu are shown to occur primarily in a propeller conformation with C3 symmetry that is stabilized by interchain hydrogen bonds. Through application of the coupled oscillator model of VCD, a right-handed sense for the hydrogen-bonded chains in the propeller is deduced, in agreement with previous empirical force field calculations. The spectra also provide evidence for interchain association between two chains, resulting in a C10-ring. For chains not involved in interchain association, the spectra reveal the presence of C7-rings within a chain. The trispeptide containing L-Ala is found to occur primarily in a random form. 相似文献
103.
The Osensjmn vendace, Coregonus albula (L.), population was founded in 1895 by introduction of about 90 000 fry from Lake Mjøsa. After 92 years, or about 46 generations of isolation, remarkable genetic changes were evident among the transplants compared to their source population. Electrophoresis of 33 enzyme loci revealed that allele frequencies differed significantly in eight of the 10 polymorphic loci. Nei's unbiased genetic distance was D = 0.012, representing the level of population differentiation usually observed among distant watercourses in vendace. Genetic variability was clearly higher among the transplants: average observed heterozygosity was 14.8% compared with 11.2% among Lake Mjøsa vendace. The high genetic variation among Osensjoen vendace shows that the divergence is not due to a small number of founders or bottlenecks in later generations. Selection by the contrasting environmental conditions between the habitats of the donor and transplanted populations is the most plausible hypothesis to explain the genetic changes in the Osensjsen vendace. 相似文献
104.
Tor Atle Mo 《Systematic parasitology》1991,20(1):11-19
On parr of Atlantic salmon Salmo salar L. in laboratory experiments at different water temperatures, opisthaptoral hard parts of Gyrodactylus salaris Malmberg, 1957 differed in size. Their shape, on the other hand, varied only slightly. The opisthaptoral hard parts were largest at the lowest water temperatures and decreased in size with increasing water temperatures (1.5°C to 20.0°C). At both 18.0°C and 20.0°C the opisthaptoral hard parts of G. salaris were smaller than has been found under natural conditions. In the experiments, the mean size of the opisthaptor in the G. salaris micropopulation at each water temperature gradually increased or decreased compared to the mean size at the start of the experiments. At the end of the experiments the mean size of the opisthaptoral hard parts in the G. salaris micropopulations showed a significant regression to the different water temperatures. 相似文献
105.
J Tor J M Llibre M Carbonell R Muga A Ribera V Soriano B Clotet M Sabriá M Foz 《BMJ (Clinical research ed.)》1990,301(6761):1130-1133
OBJECTIVE--To determine the extent of transmission of hepatitis C virus in sexual partners of intravenous drug misusers and to examine the relation between the prevalences of HIV, hepatitis B virus, and hepatitis C virus infections in homosexual men and intravenous drug misusers and their sexual partners. DESIGN--Serum samples collected between 1984 and 1988 were tested for hepatitis B virus markers and antibodies against hepatitis C virus by enzyme linked immunosorbent assay (ELISA) and for HIV antibody by enzyme immune analysis and western blotting. SETTING--Large referral university hospital with an external AIDS clinic in the metropolitan area of Barcelona, Spain. SUBJECTS--243 Intravenous drug misusers, 143 of their regular heterosexual partners, and 105 homosexual men. MAIN OUTCOME MEASURES--Prevalences of hepatitis C virus, hepatitis B virus, and HIV infections. RESULTS--In all, 178 of the 243 (73%) intravenous drug misusers, 16 out of 143 (11%) of their partners, and 17 of the 105 (16%) homosexual men had antibodies against hepatitis C virus. The presence of hepatitis C virus infection was unrelated to sex, age, the presence of HIV or hepatitis B virus infections, or the Centers for Disease Control stage of HIV. In sexual partners of intravenous drug misusers there were strong correlations between the presence of hepatitis C virus infection and that of HIV (p = 0.001) and hepatitis B virus (p = 0.013) infections. CONCLUSIONS--Intravenous drug misusers have a high risk of acquiring hepatitis C virus, hepatitis B virus, and HIV infections, but the presence of hepatitis C virus infection seems to be unrelated to the presence of the other two viruses. Homosexual men have a high prevalence of HIV and hepatitis B virus infections with a low prevalence of hepatitis C virus infection, the presence of which is not related to that of the other two infections. Conversely, heterosexual partners of intravenous drug misusers have low prevalences of the three virus infections, but the presence of hepatitis C virus infection correlates significantly with the presence of HIV and hepatitis B infections. The rate of sexual transmission of hepatitis C virus seems to be low, even in partners of people known to be seropositive for this virus. 相似文献
106.
Isolation and selection of plant growth-promoting rhizobacteria as inducers of systemic resistance in melon 总被引:1,自引:0,他引:1
Laura García-Gutiérrez Diego Romero Houda Zeriouh Francisco M. Cazorla Juan A. Torés Antonio de Vicente Alejandro Pérez-García 《Plant and Soil》2012,358(1-2):201-212
Backgroud and aims
Powdery mildew elicited by Podosphaera fusca is an important threat to cucurbits. In order to find alternatives to the current use of chemicals, we examined the potential use of plant growth-promoting rhizobacteria (PGPR) for controlling the disease by induction of systemic resistance in the host plant.Methods
A collection of Bacillus and Pseudomonas strains from different origins was studied, including strains isolated from roots of disease-free melon plants obtained from a greenhouse plagued by powdery mildew. The selection of best candidates was based on the evaluation of different traits commonly associated with PGPR, such as antifungal and siderophore production, swimming and swarming motilities, biofilm formation, auxin production and promotion of root development.Results
Three Bacillus strains, B. subtilis UMAF6614 and UMAF6639 and B. cereus UMAF8564, and two Pseudomonas fluorescens strains, UMAF6031 and UMAF6033, were selected after ranking the strains using a nonparametric statistics test. Applied to melon seedlings, the selected strains were able to promote plant growth, increasing fresh weight up to 30%. Furthermore, these strains provided protection against powdery mildew and also against angular leaf spot caused by Pseudomonas syringae pv. lachrymans, with disease reductions of up to 60%.Conclusions
These results suggest that the use of ISR-promoting PGPR could be a promising strategy for the integrated control of cucurbit powdery mildew and other cucurbit diseases. 相似文献107.
Jaime Otero Jan Henning L'Abée‐Lund Ted Castro‐Santos Kjell Leonardsson Geir O. Storvik Bror Jonsson Brian Dempson Ian C. Russell Arne J. Jensen Jean‐Luc Baglinière Mélanie Dionne John D. Armstrong Atso Romakkaniemi Benjamin H. Letcher John F. Kocik Jaakko Erkinaro Russell Poole Ger Rogan Hans Lundqvist Julian C. MacLean Erkki Jokikokko Jo Vegar Arnekleiv Richard J. Kennedy Eero Niemelä Pablo Caballero Paul A. Music Thorolfur Antonsson Sigurdur Gudjonsson Alexey E. Veselov Anders Lamberg Steve Groom Benjamin H. Taylor Malcolm Taberner Mary Dillane Fridthjofur Arnason Gregg Horton Nils A. Hvidsten Ingi R. Jonsson Nina Jonsson Simon McKelvey Tor F. Næsje Øystein Skaala Gordon W. Smith Harald Sægrov Nils C. Stenseth Leif Asbjørn Vøllestad 《Global Change Biology》2014,20(1):61-75
Migrations between different habitats are key events in the lives of many organisms. Such movements involve annually recurring travel over long distances usually triggered by seasonal changes in the environment. Often, the migration is associated with travel to or from reproduction areas to regions of growth. Young anadromous Atlantic salmon (Salmo salar) emigrate from freshwater nursery areas during spring and early summer to feed and grow in the North Atlantic Ocean. The transition from the freshwater (‘parr’) stage to the migratory stage where they descend streams and enter salt water (‘smolt’) is characterized by morphological, physiological and behavioural changes where the timing of this parr‐smolt transition is cued by photoperiod and water temperature. Environmental conditions in the freshwater habitat control the downstream migration and contribute to within‐ and among‐river variation in migratory timing. Moreover, the timing of the freshwater emigration has likely evolved to meet environmental conditions in the ocean as these affect growth and survival of the post‐smolts. Using generalized additive mixed‐effects modelling, we analysed spatio‐temporal variations in the dates of downstream smolt migration in 67 rivers throughout the North Atlantic during the last five decades and found that migrations were earlier in populations in the east than the west. After accounting for this spatial effect, the initiation of the downstream migration among rivers was positively associated with freshwater temperatures, up to about 10 °C and levelling off at higher values, and with sea‐surface temperatures. Earlier migration occurred when river discharge levels were low but increasing. On average, the initiation of the smolt seaward migration has occurred 2.5 days earlier per decade throughout the basin of the North Atlantic. This shift in phenology matches changes in air, river, and ocean temperatures, suggesting that Atlantic salmon emigration is responding to the current global climate changes. 相似文献
108.
Runar Gjerp Solstad Chun Li Johan Isaksson Jostein Johansen Johan Svenson Klara Stensv?g Tor Haug 《PloS one》2016,11(3)
The global problem of microbial resistance to antibiotics has resulted in an urgent need to develop new antimicrobial agents. Natural antimicrobial peptides are considered promising candidates for drug development. Echinoderms, which rely on innate immunity factors in the defence against harmful microorganisms, are sources of novel antimicrobial peptides. This study aimed to isolate and characterise antimicrobial peptides from the Edible sea urchin Echinus esculentus. Using bioassay-guided purification and cDNA cloning, three antimicrobial peptides were characterised from the haemocytes of the sea urchin; two heterodimeric peptides and a cysteine-rich peptide. The peptides were named EeCentrocin 1 and 2 and EeStrongylocin 2, respectively, due to their apparent homology to the published centrocins and strongylocins isolated from the green sea urchin Strongylocentrotus droebachiensis. The two centrocin-like peptides EeCentrocin 1 and 2 are intramolecularly connected via a disulphide bond to form a heterodimeric structure, containing a cationic heavy chain of 30 and 32 amino acids and a light chain of 13 amino acids. Additionally, the light chain of EeCentrocin 2 seems to be N-terminally blocked by a pyroglutamic acid residue. The heavy chains of EeCentrocins 1 and 2 were synthesised and shown to be responsible for the antimicrobial activity of the natural peptides. EeStrongylocin 2 contains 6 cysteines engaged in 3 disulphide bonds. A fourth peptide (Ee4635) was also discovered but not fully characterised. Using mass spectrometric and NMR analyses, EeCentrocins 1 and 2, EeStrongylocin 2 and Ee4635 were all shown to contain post-translationally brominated Trp residues in the 6 position of the indole ring. 相似文献
109.
We describe procedures for the synthesis of a fluorescent pyrimidine analog and its site-specific incorporation into a DNA oligomer. The 5'-protected and 3'-activated nucleoside 4 is synthesized in three steps with an overall yield of 40%. Site-specific incorporation into a DNA oligomer occurs with greater than 88% coupling efficiency. This isosteric fluorescent DNA analog can be used to monitor denaturation of DNA duplexes via fluorescence and can positively detect the presence of abasic sites in DNA duplexes. The total time for synthesis of the phosphoramidite 4 is about 75 h, whereas the total time for site-specific incorporation of nucleoside 2 into an oligonucleotide and purification of the corresponding oligonucleotide is about 114 hours. 相似文献
110.
Liu K Wahlberg P Leonardsson G Hägglund AC Ny A Bodén I Wibom C Lund LR Ny T 《Developmental biology》2006,295(2):615-622
Many studies have suggested the hypothesis that the plasminogen activator (PA) system and the matrix metalloproteinase (MMP) system, either separately or in combination, may provide the proteolytic activity that is required for rupture of the follicular wall at the time of ovulation. Our recent studies on ovulation in plasminogen (plg)-deficient mice have, however, shown that plasmin is not required for normal ovulation, leading us to the hypothesis that MMPs may be a more important source of proteolysis for this process. To investigate the role of MMPs and also the possibility of a functional overlap or synergy between the MMP and PA systems during ovulation, we have studied ovulation efficiency in wild-type and plg-deficient mice treated with the broad-spectrum MMP inhibitor galardin. We found that in both wild-type mice and heterozygous plg-deficient (plg+/-) mice that had been treated with galardin prior to ovulation, there was a mild (18-20%) reduction in ovulation efficiency. Surprisingly, galardin treatment of plg-deficient (plg-/-) mice only caused an additional 14% reduction in ovulation efficiency as compared to vehicle-treated plg-/- mice. Our data therefore suggest that although MMPs may play a role in degradation of the follicular wall, they may not be obligatory for ovulation. In contrast to previous studies on tissue remodeling during wound healing and placental development, we have demonstrated that there is no obvious functional overlap or synergy between the PA and MMP systems, which has previously been thought to be essential for the ovulatory process. 相似文献