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181.
P. A. Scolnik P. Hinton I. M. Greenblatt G. Giuliano M. R. Delanoy D. L. Spector D. Pollock 《Planta》1987,171(1):11-18
The tomato (Lycopersicon esculentum (L.) Mill.) ghost plant is a mutant of the San Marzano cultivar affected in carotenoid biosynthesis. ghost plants exhibit a variable pattern of pigment biosynthesis during development. Cotyledons are green but true leaves are white. Green sectors, which appear to be clonal in origin, are frequently observed in the white tissue. Because of the lack of photosynthesis ghost plants have a very low viability in soil. We have developed a strategy for propagating ghost plants that employs organ culture to generate variegated green-white plants which, supported by the photosynthetic green areas, develop in soil to almost wild-type size. These plants were used to analyze the pigment content of the different tissues observed during development and plastid ultrastructure. Cotyledons and green leaves contain both colored carotenoids and chlorophyll but only the colorless carotenoid phytoene accumulates in white leaves. the plastids in the white tissue of ghost leaves lack internal membrane structures but normal chloroplasts can be observed in the green areas. The chromoplasts of white fruits are also impaired in their ability to form thylakoid membranes. 相似文献
182.
The amount of in-vitro translatable mRNA of the light-harvesting chlorophyll a/b-binding protein (LHCP) of photosystem II strongly increases in darkness (D) after a 5-min red-light pulse while continuous illumination of mustard seedlings with far-red (FR), red or white light leads only to a slight increase in the amount of translatable LHCP-mRNA. No increase can be observed after a long-wavelength FR (RG9-light) pulse. However, a FR pretreatment prior to the RG9-light pulse strongly increase LHCP-mRNA accumulation in subsequent D. This is not observed in the case of the mRNA for the small subunit of ribulose-1.5-bisphosphate carboxylase. The increase of LHCP-mRNA in D after a FR pretreatment can be inhibited by a reillumination of the seedlings with FR. The inhibition of LHCP-mRNA accumulation during continuous illumination with FR and the strong increase in D following a FR illumination was found to be independent of chlorophyll biosynthesis since no correlation between chlorophyll biosynthesis and translatable LHCP-mRNA levels could be detected. Even strong changes in the amount of intermediates of chlorophyll biosynthesis caused by application of levulinic acid or 5-aminolevulinic acid did not affect LHCP-mRNA levels. Therefore, we conclude that the appearance of LHCP-mRNA is inhibited during continuous illumination, even though illumination leads to a storage of a light singal which promotes accumulation of translatable LHCP-mRNA in D.Abbreviations c
continuous
- Chl
chlorophyll
- D
darkness
- FR
far-red light (3.5 W·m-2)
- LHCP
light-harvesting chlorophyll a/b-binding protein of photosystem II
- NF
Norfluration
- PChl
protochlorophyll(ide)
- Pfr
far-red absorbing form of phytochrome
- Ptot
total phytochrome
- R
red light (6.8 W·m-2)
- RG9-light
long-wavelength FR (10 W·m-2)
- SSU
small subunit of ribulose-1.5-bisphosphate carboxylase
- WL
white light
- ()
Pfr/Ptot=wavelength-dependent photoequilibrium of the phytochrome system 相似文献
183.
Excised pumpkin (Cucurbita pepo L.) cotyledons were used to investigate the effects of two different types of cytokinins: N6-benzyladenine and N1-(2-chloro-4-pyridyl)-N2-phenylurea on RNA synthesis in isolated nuclei. Treatment of cotyledons with both cytokinins resulted in a rapid enhancement of nuclear RNA-polymerase-I activity (EC 2.7.7.6). Maximum stimulation of RNA polymerase I, responsible for rRNA synthesis, was observed 4–6 h after the start of cytokinin action. The activity of RNA polymerase II was stimulated much more slowly and to a lesser extent. Uridine 5-monophosphate-uridine analysis of the alkalidigested nascent pre-rRNA chains showed that the stimulation of RNA-polymerase-I activity was the consequence of an increase of the polyribonucleotide-clongation rate. No significant change in the number of transcribing enzyme molecules was defected after hormone treatment (86·103 RNA-polymerase-I molecules per diploid genome).Indications that de-novo protein synthesis is necessary for cytokinin-mediated RNA-polymerase stimulation were derived from experiments showing inhibition by cycloheximide.Abbreviations BA
N6-benzyladenine
- [PU]-30
N1-(2-chloro-4-pyridyl)-N2-phenylurea
- UMP
undine 5-monophosphate
- UTP
udine 5-triphosphate 相似文献
184.
Structure and expression of the overlapping ND4L and ND5 genes of Neurospora crassa mitochondria 总被引:1,自引:0,他引:1
Summary Genes homologous to the mammalian mitochondrial NADH dehydrogenase subunit genes ND4L and ND5 were identified in the mitochondrial genome of the filamentous fungus Neurospora crassa, and the structure and expression of these genes was examined. The ND4L gene (interrupted by one intervening sequence) potentially encodes an 89 residue long hydrophobic protein that shares about 26% homology (or 41% homology if conservative amino acid substitutions are allowed) with the analogous human mitochondrial protein. The ND5 gene (which contains two introns) encodes a 715 residue polypeptide that shares 23% homology with the human analogue; a 300 amino acid long region is highly conserved (50% homology) in the two ND5 proteins. The stop codon of the ND4L gene overlaps the initiation codon of the downstream ND5 gene, and the two genes are contranscribed and probably cotranslated. A presumed mature dicistronic (ND4L plus ND5) RNA was detected. The postulated mRNA (about 3.2 kb) contains 5 and 3 non-coding regions of about 86 and 730 nucleotides, respectively; this species is generated from very large precursor RNAs by a complex processing pathway. The ND4L and ND5 introns are all stable after their excision from the precursor species.Abbreviations bp
base pairs
- rRNA
ribosomal RNA
- ND
NADH dehydrogenase
- URF
unidentified reading frame
- kDal
kilodaltons; a.a., amino acid 相似文献
185.
L. Jouanin P. Guerche N. Pamboukdjian C. Tourneur F. Casse Delbart J. Tourneur 《Molecular & general genetics : MGG》1987,206(3):387-392
Summary The structure of the T-DNA in Ri-transformed plants of Brassica napus, Nicotiana plumbaginifolia and Nicotiana tabacum was analysed. All the plants studied present a particular phenotype with wrinkled leaves. The T-DNA is composed of two parts: TL and TR. The size of the TL-DNA (19–20 kb) seems to be almost constant, except in N. tabacum where it is shorter. The TR-DNA can be absent, and its size varies from about 5–28 kb, with two predominant lengths. The smaller size does not include the region homologous to the tms genes of the pTi T-DNA. The copy number varies from one to four copies per plant genome. TL and TR-DNA are not always present in the same copy number, but in some cases are linked together. 相似文献
186.
Ethylene production of habituated and auxin-requiring tobacco ( Nicotiana tabacum L. cv. Xanthi) callus cultures were compared. More ethylene was produced by auxinrequiring i.e. auxin-heterotrophic cultures than by habituated ones. Treatment with 2,4-dichlorophenoxyacetic acid increased the ethylene evolution of habituated cultures over the range 10−7 to 10−4 M , which suggests that the higher ethylene production of auxin-dependent callus is caused by the 2,4-D in the medium. The IAA levels depended on the age of both types of callus cultures. 相似文献
187.
In the developing peanut (Arachis hypogaea L.) kernels, the period between 15 and 35 days after podding (DAP) was identified as the active period of oil-filling. The
period of active oil-filling was associated with a decrease in the starch, soluble sugars and proteins so as to make available
the energy and carbon skeleton for the synthesis of oil. The oil content in the mature kernels decreased by 11, 12 and 25
per cent with Zn, S and Zn+S deficiency, respectively. In addition, proteins and starch content decreased significantly while
that of soluble sugars increased slightly. The activity of malate dehydrogenase and glucose-6-phosphate dehydrogenase also
decreased due to Zn as well as S deficiency. The deficiency treatments resulted in a decrease in phospholipids, free fatty
acids and triacylglycerols in mature kernels. Further the proportion of 16∶0 and 18∶2 decreased while that of 18∶1 increased
in developing kernels. 相似文献
188.
M. Buiatti C. Simeti S. Vannini G. Marcheschi A. Scala P. Bettini P. Bogani M. G. Pellegrini 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1987,75(1):37-40
Summary To obtain Tomato cell lines with an altered capacity to respond to heat-released cell wall components (elicitor) of a tomato pathogen (Fusarium oxysporum f. sp. lycopersici), positive and negative selection experiments, using BUdR enrichment techniques, were carried out on suspension cultures of the susceptible, low phytoalexin producer cultivar Red River. Both high and low phytoalexin producing clones were isolated. Further tests demonstrated that not all phytoalexin-producing clones were more susceptible to the elicitor toxic effect, and that they were altered also in the speed of response to fungal cell wall components. Cells selected with Fusarium elicitor showed the same behaviour when challenged by Phytophthora infestans elicitor, thus suggesting in this case lack of specificity. The results are finally discussed with a view to using the technique both as a tool to study the genetics and physiology of hostparasite interactions and as a possible new method for the selection of pathogen resistant genotypes.Paper no. 1224 IPRA-CNR; research supported by an EEC-BAP contract 相似文献
189.
The mean dimensions of thecis N-methyl peptide unit have been arrived at by analysing the crystal structure data on compounds containing such units. These
dimensions can be used as standard in conformational studies on cyclic peptides. While the bonds meeting at C are almost coplanar,
those meeting at N show a slight pyramidal disposition. A comparison of the dimensions of the normal and N-methylatedcis peptide units show that there are perceptible differences in the parameters connected with N. In addition, the flexibility
of thecis peptide unit has been analysed by studying the distribution of the parameters in different classes of compounds such as cyclic
di, tri and higher peptides. The salient features are: (i) The angle CαCN in cyclic dipeptide and the angle CδNCα in higher peptides tend to be lower, when the peptide unit is associated with a prolyl residue; (ii) in cyclic tripeptides
the internal anglesviz., CαCN and CNCα are significantly larger thereby increasing the intra-annular space; (iii) the bond Cα-C is distinctly shorter when it occurs in cyclic dipeptides. The results lead to the conclusion that thecis peptide unit takes up aneed-based flexibility in its dimension. 相似文献
190.
S. K. Podder A. Chakraborti K. Vijayalakshmi P. Lalit Kumar Singh 《Journal of biosciences》1987,11(1-4):495-502
To examine how surface Potential controls the reactivity of glycoconjugates at cell surface, the interaction of galactose-sPecific
lectinse.g. peanut agglutinin,Ricinus cummunis agglutinin with liPosomes bearing asialo GM1 were studied in the Presence of varying amount of ganglioside mixture, GMn. The Presence of 5% GMn causes comPlete slowing down of PreciPitin reaction and thereby make carbohydrate moiety of asialo GM1 comPletely inaccessiblei.e. ‘cryPtic’. In contrast the Presence of 1–2% GMn enhances the aPParent rate and amPlitude of the PreciPitin reaction as surface Potential becomes more negative. The relevance
of the findings has been discussed in relation to the exPression and involvement of the cell-surface sialic acid residues
during develoPment and differentiation. 相似文献