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461.
462.
Stepanova V. P. Davydenko S. G. Donich V. N. Smolina S. S. Kurennaya O. N. Yarovoy B. F. 《Russian Journal of Genetics》2001,37(4):460-463
Yeast mutants resistant to a toxic lysine analog, thialysine were obtained by a method described in the literature [1]. A strain excreting the maximum amount of lysine (0.45 g/l) was selected from these mutants. The intracellular content of lysine was also increased by 30%. The genetic nature of lysine overproduction was studied in this strain. An increase in the amount of excreted lysine was shown to be determined by at least two genes, one of which carries a mutation of thialysine resistance manifesting the pleiotropic effect of lysine overproduction (Th1
R) and the other is involved in the regulation of lysine production (PRL). Linkage groups of these genes were determined: the first gene was mapped to the IV chromosome and the second, to the XV chromosome. Both genetic characters were introduced into industrial baker's yeast strains via a series of backcrosses. The stabilization of the genome in the newly derived strains was confirmed by electrokaryotyping. 相似文献
463.
B A Timofeev I M Bolotin L P Stepanova A A Bogdanov Kh Georgiu S N Malyshev A L Petrovski?Klibanov V P Torchilin 《Antibiotiki i khimioterapii͡a》1991,36(9):34-36
The cultures of Nuttalia eque mainly develop in the reticuloendothelial organs and so in treatment of nuttaliosis in horses and the Nuttalia carriers diamidine, an analog of imidocarb or imidozoline, was used encapsulated in liposomes. The liposomes were prepared with a modification of the phase inversion method (the lipids were dissolved in a mixture of freon-11 and chloroform). The content of the organic solvents in the preparation, as evidenced by gas liquid chromatography, was less than 0.2 per cent. The main fraction consisted of particles 1.5 to 2.5 microns in diameter. The tests on animals of various species revealed a significant decrease in the toxicity of diamidine when used encapsulated in liposomes as compared to the use of the free diamidine. The LD50 of the liposome encapsulated diamidine administered intravenously and intramuscularly was for albino mice 52 and 6000 mg/kg, respectively whereas that of the free diamidine was 0.8 and 84 mg/kg, respectively. In a dose of 10 mg/kg administered intramuscularly the free diamidine induced death in 100 per cent of the horses while in a dose of 10 mg/kg the liposome encapsulated diamidine was satisfactorily tolerated by the animals. The liposome encapsulated diamidine had no unfavourable effect on hepatic antitoxic and metabolic functions. One should hope that the low toxicity of the liposome-encapsulated diamidine will provide its higher chemotherapeutic index. 相似文献
464.
SHERWIN HEATHER W.; PAMMENTER N. W.; FEBRUARY ED; VANDER WILLIGEN CLARE; FARRANT JILL M. 《Annals of botany》1998,81(4):567-575
Myrothamnus flabellifoliusWelw. is a desiccation-tolerant (resurrection)plant with a woody stem. Xylem vessels are narrow (14 µmmean diameter) and perforation plates are reticulate. This leadsto specific and leaf specific hydraulic conductivities thatare amongst the lowest recorded for angiosperms (ks0.87 kg m-1MPa-1s-1;kl3.28x10-5kg m-1MPa-1s-1, stem diameter 3 mm). Hydraulic conductivitiesdecrease with increasing pressure gradient. Transpiration ratesin well watered plants were moderate to low, generating xylemwater potentials of -1 to -2 MPa. Acoustic emissions indicatedextensive cavitation events that were initiated at xylem waterpotentials of -2 to -3 MPa. The desiccation-tolerant natureof the tissue permits this species to survive this interruptionof the water supply. On rewatering the roots pressures thatwere developed were low (2.4 kPa). However capillary forceswere demonstrated to be adequate to account for the refillingof xylem vessels and re-establishment of hydraulic continuityeven when water was under a tension of -8 kPa. During dehydrationand rehydration cycles stems showed considerable shrinking andswelling. Unusual knob-like structures of unknown chemical compositionwere observed on the outer surface of xylem vessels. These maybe related to the ability of the stem to withstand the mechanicalstresses associated with this shrinkage and swelling.Copyright1998 Annals of Botany Company cavitation, desiccation, hydraulic conductivity, refilling, resurrection plant, root pressure, xylem anatomy,Myrothamnus flabellifolius 相似文献
465.
L S Malykhina G A Stepanova G N Popova N A Fedorov 《Biulleten' eksperimental'no? biologii i meditsiny》1976,81(4):428-430
Nasal polyp tissue possess adenylatecyclase activity. Under conditions of incubation of nasal polyps with the use of reserpine (an activator of serotonin synthesis in this tissue) there can be observed a statistically significant increase of adenylatecyclase activity. During the first minutes of the polyp incubation with reserpine the activity of the enzyme rose ten-fold. Participation of the adenylatecyclase system at the initial stages of morphological and biochemical differentiation, accompanying serotonin biosynthesis in human nose polyps was confirmed. 相似文献
466.
The possibility of use of 7-amino-actinomycin D (7aAMD)--fluorescent analog of actinomycin D--as a specific dye for DNA staining in the suspended cells was studied by means of laser flow-cytometry. The optimal conditions for staining were obtained: 7aAMD concentration 10(-5) M, pH 7, staining time 20 min, 37 degrees C, ionic strength 0.15 M Na+. In this case the fluorescent signal is proportional to the DNA amount and coefficient of variation is about 0.03. The influence of the stepwise extraction of the proteins from chromatin also was studied. In the course of the salt deproteinization the fluorescence intensity gradually rose thus showing the increase of the binding sides-number. The deproteinization of cells nuclei by 0.1 HCl increased the number of binding sites 2.5 times more. It was shown that the incubation of cells with RNAse at elevated ionic strength (0.3-0.7 M NaCl) leads to an additional increase of the cell fluorescence and produces no effect at low and normal ionic strength. The deproteinizing effect of RNAse and its possible mechanism is discussed. 相似文献
467.
L V Vlasova S F Zakirova B M Lialiuk G P Stepanova L A Gul'man 《Zhurnal mikrobiologii, epidemiologii, i immunobiologii》1984,(5):79-82
The etiology of acute infectious diseases accompanied by uveitis in young children has been studied. In these investigations a high degree of contamination with virus ECHO 19 in patients with acute diseases accompanied by uveitis has been revealed and the ophthal motropic properties of the virus have been experimentally established, which indicates that certain variants of virus ECHO 19 play, probably, some role in the etiology of uveitis in young children. 相似文献
468.
469.
470.
Iu V Vertiev I A Shaginian M V Stepanova Iu V Ezepchuk 《Molekuliarnaia genetika, mikrobiologiia i virusologiia》1985,(3):38-40
A solid phase variant of radioimmunoassay has been elaborated for screening toxin-producing strains of E. coli and V. cholerae grown on agar plates. The method is based on the ability of cholera-like toxins to be absorbed on nitrocellulose filters and their further identification with the use of homologous sera and [125I]-A protein from staphylococci. Sensitivity of the method reaches 20 pg. The proposed technique permits identification of intracellular enterotoxin and is aimed at a massive screening of E. coli strains, NAG-vibrios and V. cholerae strains for toxin production. 相似文献