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71.
72.
INTRoDUCTIoNlYho1iumrePensL,whiteclover,isaneconomicallyimportantplantspeciesintemperatepastures.Asbrieflyreportedby[1],ithas16pairsofchromosomes(2n=32).Asyet,nodetailedcytologicalexaminationofthisspecies,suchasC-banding,hasbeenrep0rted.Inthelastdecade,thetechnique0fC-bandinghasbeenusedt0examinehighlyrepeatedsequencesinplantchrom0s0mesandhasprovidedausefultoolf0rtheanalysis0fcyt0geneticstructureincr0pplants[2-71.Inplants,thechr0m0s0mall0calizationofhighlyrepeatedDNAsequencesbyinsituhybr… 相似文献
73.
74.
The period (per) locus has received much attention in molecular evolution
studies because it is one of the best studied "behavioral genes" and
because it offers insight into the evolution of repetitive sequences. We
studied most of the coding region of per in Drosophila willistoni and
confirmed previously observed patterns of conservation and divergence among
distantly related species. Five regions are so highly diverged that they
cannot be aligned, whereas a region encompassing the PAS domain is very
conserved. Structural and nucleotide polymorphism patterns in the
willistoni group are not the same as those observed in previously studied
species. We sequenced the region homologous to the highly polymorphic
threonine-glycine repeat of D. melanogaster in multiple strains of D.
willistoni, as well as in other members of willistoni group, and found an
unusual amount of conservation in this region. However, the next
nonconserved region downstream in the sequence is quite variable and
polymorphic for the number of repeated glycines. The glycine codon usage is
significantly different in this glycine repeat as compared to other parts
of the gene. We were able to plot the directionality of change in the
glycine repeat region onto a phylogeny and find that the addition of
glycines is the general trend with the diversification of the willistoni
group.
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75.
76.
Role of platelet-activating factor (PAF) in the initiation of the decidual reaction in the rat 总被引:1,自引:0,他引:1
Injection of PAF into the left uterine horn induced a dose-dependent decidua-like reaction in the pseudopregnant rat. This reaction was maximal when PAF was injected at Day 5 of pseudopregnancy and was blocked by the specific PAF antagonist, BN 52021. BN 52021 did not interfere with the decidual reaction induced by prostaglandin E-2 or insertion of a cotton thread in the uterine horn. In contrast, a decidua-like reaction was not evoked by the inactive lyso-PAF, demonstrating the specificity of the action of PAF. The decidua-like reaction induced by PAF involves the generation of cyclooxygenase metabolites of arachidonic acid since it was inhibited by indomethacin. The histological alterations induced by PAF were similar to those observed after embryo implantation, strengthening the postulate for a role of the autacoid in the early stages of pregnancy. 相似文献
77.
78.
M Benhamou E Ninio P Salem C Hieblot G Bessou C Pitton F T Liu J M Mencia-Huerta 《Journal of immunology (Baltimore, Md. : 1950)》1986,136(4):1385-1392
The effect of dexamethasone (DM) on the immunologic and nonimmunologic release of paf-acether and of the granule marker beta-hexosaminidase (BHEX) from mouse bone marrow-derived mast cells (BMMC) was studied. BMMC (1 X 10(6] in a modified Tyrode's solution containing 0.25% bovine serum albumin (BSA) were sensitized with an optimal dose of dinitrophenyl (DNP)-specific monoclonal IgE, and were washed before challenge with 40 ng/ml of DNP coupled to BSA. Preincubation of BMMC for 24 hr with 1 nM to 1 microM DM inhibited in a dose-dependent fashion the immunologic release of paf-acether and of BHEX as compared with control cells, with a half-maximal effect at 20 nM and 4 nM respectively. By contrast, the ionophore A23187 (1 microM)-induced release of paf-acether and of BHEX was unaffected by DM pretreatment. Finally, the antigen-induced increase in acetyltransferase activity, used as an index of cellular activation, was inhibited by 37 +/- 16% in 1 microM DM-treated BMMC as compared with untreated cells. Preincubation of BMMC with DM for 24 hr caused a dose-dependent inhibition of 125I-IgE binding to the cells, with a half-maximal effect at 14 nM. As determined by Scatchard analysis, the number of IgE Fc receptors was decreased by 55% in 1 microM DM-treated BMMC as compared with untreated cells, although the dissociation constants were comparable (control: 12.6 +/- 4.1 nM; DM-treated cells: 14.1 +/- 6.7 nM; mean +/- 1 SD; n = 3). Cytofluorometer analysis of BMMC sensitized with a saturating amount of purified monoclonal IgE, followed by addition of a fluoresceinated anti-mouse IgG (heavy and light chains), revealed a single cellular population for both DM-treated and untreated BMMC. This demonstrates that the DM-induced decrease in IgE Fc receptor expression was exhibited by every BMMC. The possible link between the decreased sensitization of the cells consequent to the reduction in IgE Fc receptor expression and the alteration of the secretory response and acetyltransferase activity was investigated. BMMC were incubated with IgE under experimental conditions giving half-sensitization of the cells. Upon antigen challenge, a 10.5 +/- 3.7% decrease in acetyltransferase activity and a 29.2 +/- 3.5% decrease in paf-acether release were observed with half-sensitized cells as compared with cells sensitized with a saturating amount of IgE.(ABSTRACT TRUNCATED AT 400 WORDS) 相似文献
79.
The authors have investigated the electrical activity of corpus cavernous, first according to Wagner and Gerstenberg’ method, then, since one year, according to Stief method, in the basal state and following intracavernosal injection of vasoactive agents, or following various stimulation tests. They have found again the electrical activity described by these authors, but have been confronted with the difficulty in quantifying the data. Specially single potential analysis seems to them little reliable and reproducible for an objective interpretation. At this stage of their experience, they test two simpler criteria interpretation: the richness of the electrical activity, and the reactivity of the recording to various stimulations. Their preminary results suggest a correlation between those criteria and the state of the autonomic nervous system of the penis. 相似文献
80.
Complete sequences of the rRNA genes of Drosophila melanogaster 总被引:19,自引:0,他引:19
In this, the first of three papers, we present the sequence of the
ribosomal RNA (rRNA) genes of Drosophila melanogaster. The gene regions of
D. melanogaster rDNA encode four individual rRNAs: 18S (1,995 nt), 5.8S
(123 nt), 2S (30 nt), and 28S (3,945 nt). The ribosomal DNA (rDNA) repeat
of D. melanogaster is AT rich (65.9% overall), with the spacers being
particularly AT rich. Analysis of DNA simplicity reveals that, in contrast
to the intergenic spacer (IGS) and the external transcribed spacer (ETS),
most of the rRNA gene regions have been refractory to the action of
slippage-like events, with the exception of the 28S rRNA gene expansion
segments. It would seem that the 28S rRNA can accommodate the products of
slippage-like events without loss of activity. In the following two papers
we analyze the effects of sequence divergence on the evolution of (1) the
28S gene "expansion segments" and (2) the 28S and 18S rRNA secondary
structures among eukaryotic species, respectively. Our detailed analyses
reveal, in addition to unequal crossing-over, (1) the involvement of
slippage and biased mutation in the evolution of the rDNA multigene family
and (2) the molecular coevolution of both expansion segments and the
nucleotides involved with compensatory changes required to maintain
secondary structures of RNA.
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