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81.
82.
A heat-shock promoter fusion to the Ac transposase gene drives inducible transposition of a Ds element during Arabidopsis embryo development 总被引:1,自引:0,他引:1
Lluis Balcells Eva Sundberg George Coupland 《The Plant journal : for cell and molecular biology》1994,5(5):755-764
A heat-shock promoter fusion to the Ac transposase gene (hs::TPase) was constructed and introduced into Arabidopsis. In five transformants containing the fusion the abundance of transposase mRNA increased approximately 120-fold on exposure to high temperatures. Hybrid plants containing hs::TPase and a Ds element inserted in a streptomycin resistance gene (Ds::SPT) were made and these plants were self-fertilized either after heat shocking at different stages in development or without exposure to high temperature. The progeny of these plants were sown on streptomycin-containing medium and the frequency with which variegated or streptomycin-resistant (strepR) seedlings occurred was used as an indication of the frequency of Ds excision. Very few of the progeny of plants not exposed to heat shock or of those heat shocked only during vegetative development were variegated or strepR. However, plants that were heat shocked after the appearance of flower buds and during seed development produced high frequencies (approaching 100%) of variegated, but very few strepR, progeny. Furthermore, when variegated seedlings were grown to maturity and self-fertilized without further exposure to heat shock then strepR seedlings often occurred at high frequency among their progeny. Southern analysis indicated that the majority of these strepR plants contained a transposed Ds at a new location. These data indicate that in response to heat shock Ds excision frequently occurs in embryonic cells which ultimately give rise to the gametes, as well as in cells of the developing cotyledons. The importance of an inducible transposon system for transposon tagging is discussed. 相似文献
83.
84.
Numerous studies have demonstrated that several diseases and stress conditions are associated with changes in the levels of zinc in the blood plasma and cellular elements. In this research the association between serum zinc concentrations and other hematic parameters of diagnostic interest has been evaluated. Quantitative determinations of zinc, total plasmatic proteins, albumin, hemoglobin and calculation of mean corpuscular volume were performed on blood samples from 58 males aged 20–61 years. Concentrations measured in our sample are comparable with reference values. Statistically significant correlation coefficients were found between age and albumin (r = - 0.562, P < 0.001), serum zinc and albumin (r = 0.328, P < 0.05), serum zinc and hemoglobin (r = 0.291, P < 0.05), and total plasmatic proteins and albumin (r = 0.463, P < 0.001). These correlation coefficients were significant even after adjustment for age effect. The determination of serum zinc concentration may be useful in the assessment of clinical scenarios. Particularly, it may provide additional information for the diagnosis of specific pathologies, such as hepatic malfunctions. It could also be useful in the identification of different stages of anemia. 相似文献
85.
Calvin cycle genes in Nitrobacter vulgaris T3 总被引:1,自引:0,他引:1
Maren Strecker Eva Sickinger Robert S. English Jessup M. Shively 《FEMS microbiology letters》1994,120(1-2):45-50
Abstract The genes encoding the Calvin cycle enzymes of Nitrobacter vulgaris T3 are found as two separate clusters on the chromosome. One cluster contains the genes for the large and small subunits of ribulose-1,5-biphosphate carboxylase/oxygenase (RuBisCO), glyceraldehyde-3-phosphate dehydrogenase, and one encoding a regulatory protein of the LysR family. The other cluster contains the genes for fructose-1,6-/sedoheptulose-1,7-bisphosphatase, phosphoribulokinase, and fructose-1,6-/sedoheptulose-1,7-biphosphate aldolase. With the exception of the LysR-like gene, the genes in each cluster are apparently transcribed in the same direction. The deduced amino acid sequence of both the large and small subunits of RuBisCO are most similar (84–86%) to those of Thiobacillus ferrooxidans and Chromatium vinosum . The deduced sequences of phosphoribulokinase and fructose/sedoheptulose bisphosphatase are 67–73 aand 44–46% similar to those reported for other autotrophic bacteria, respectively. 相似文献
86.
Summary We used in vitro growth inhibition assays to demonstrate that synthetic cecropin protein has potent activity against a range of plant pathogenic bacteria. We then prepared transgenic tobacco plants which express cecropin mRNA and protein. We have used Pseudomonas syringae pv tabaci infection of these transgenic tobacco as a model system to evaluate whether the plants which express cecropin protein also have increased tolerance to infection. We found no dramatic difference in disease response between plants which are expressing cecropin protein and control plants which were derived from the transformation with a binary vector which did not carry the gene encoding cecropin protein. 相似文献
87.
David J. Munroe Melanie Haas Eva Bric Tania Whitton Hiroyuki Aburatani Kent Hunter David Ward David E. Housman 《Genomics》1994,19(3)
A significant issue in the analysis of any genomic DNA segment is the generation of a unique set of short single-copy sequences that are representative of that region. In this report we describe a novel technique, IRE-bubble PCR, which was designed to amplify the human DNA content of somatic cell hybrids, YACs, cosmids, and λ phage and result in greater complexity and representation than standard inter-IRE, PCR. Here we demonstrate that IRE-bubble PCR is species specific and that it results in the generation of a product that is at least 10-fold more complex and representative than that produced by standard inter-IRE PCR. In addition, we have addressed the factors that contribute to the representation of the IRE-bubble PCR product and show how they may be used to further increase the complexity of this reaction. Finally, we have illustrated how the complexity and distribution of products generated by IRE-bubble PCR can be exploited and applied to FISH mapping and "chromosome painting" as well as to the generation of STSs targeted to specific chromosomal or subchromosomal regions. 相似文献
88.
During sequence analysis of the first intron of the human c-fms oncogene, we identified an open reading frame encoding the ribosomal protein L7 (RPL7). The presence of this sequence within intron 1 of the c-fms gene was confirmed by Southern blot hybridization and by sequence analysis of two independent cosmid clones (cos2-e and cos1-22) that span the human genomic c-fms locus. The RPL7 sequence was detected in a region of sequence overlapped by the cos2-e and cos1-22 cosmid clones but oriented opposite to the c-fms gene. We demonstrated that the sequence is identical to the full-length RPL7 cDNA sequence, but lacks any recognizable introns, has a 30-bp poly(A) tail, and is bracketed by two perfect direct repeats of 14 bp. We also showed that despite the fact that the 5′ flanking region of the RPL7 sequence contains a potential TATA box upstream of an intact open reading frame, this pseudogene (RPL7P) is not actively transcribed. 相似文献
89.
Deborah Long June Swinburne Marta Martin Kate Wilson Eva Sundberg Karen Lee George Coupland 《Molecular & general genetics : MGG》1993,241(5-6):627-636
The Ac/Ds transposon system of maize shows low activity in Arabidopsis. However, fusion of the CaMV 35S promoter to the transposase gene (35S::TPase) increases the abundance of the single Ac mRNA encoded by Ac and increases the frequency of Ds excision. In the experiments reported here it is examined whether this high excision frequency is associated with efficient re-insertion of the transposon. This was measured by using a Ds that carried a hygromycin resistance gene (HPT) and was inserted within a streptomycin resistance gene (SPT). Excision of Ds therefore gives rise to streptomycin resistance, while hygromycin resistance is associated with the presence of a transposed Ds or with retention of the element at its original location. Self-fertilisation of most individuals heterozygous for Ds and 35S::TPase produced many streptomycin-resistant (strepr) progeny, but in many of these families a small proportion of strepr seedlings were also resistant to hygromycin (hygr). Nevertheless, 70% of families tested did give rise to at least one strepr, hygr seedling, and over 90% of these individuals carried a transposed Ds. In contrast, the Ac promoter fusion to the transposase gene (Ac::TPase) produced fewer streprhygr progeny, and only 53% of these carried a transposed Ds. However, a higher proportion of the strepr seedlings were also hygr than after activation by 35S::TPase. We also examined the genotype of strepr, hygr seedlings and demonstrated that after activation by 35S::TPase many of these were homozygous for the transposed Ds, while this did not occur after activation by Ac::TPase. From these and other data we conclude that excisions driven by 35S::TPase usually occur prior to floral development, and that although a low proportion of strepr progeny plants inherit a transposed Ds, those that do can be efficiently selected with an antibiotic resistance gene contained within the element. Our data have important implications for transposon tagging strategies in transgenic plants and these are discussed. 相似文献
90.
Eva Kot Robin Miller-Catchpole Anatoly Bezkorovainy 《Biological trace element research》1993,38(1):1-12
Protoplasts ofBifidobacterium thermophilum were prepared by a combination of lysozyme and protease digestion, and ferrous iron uptake studies were carried out. Little,
if any, iron was internalized by the protoplasts, although large amounts of iron were bound to the protoplast surface. This
binding was much greater than that of intact cells, which prefer to internalize iron by an energy-dependent process. It was
also found that the binding of iron by protoplasts of cells grown in an iron-deficient medium was much more extensive than
that of cells grown in an iron-sufficient medium. Soluble and particulate fractions of protoplasts were prepared by grinding
them in a glass homogenizer, and the particulate fraction was also subjected to iron binding studies. The amount of iron bound
was the same as that in intact protoplasts, indicating that the particulate fraction membrane fragments bound iron on their
outer surface only. Nevertheless, when iron-preloaded cells were protoplasted and their surface cleared of iron, their particulate
fraction contained considerable amounts of iron, indicating that the inner surface of the membranes is capable of binding
iron as long as the cell is intact. The amount of iron so bound was dose-dependent on the amount of iron entering the cell.
The failure of the outer and inner surface iron pools to mix was confirmed by the fact that when iron-preloaded protoplasts
were incubated with additional iron, only the latter (surface-bound) was elutable with nonradioactive 2 mM FeSO4. It is concluded that increasing bifidobacterial iron load increases the amount of iron bound to the inner surface of the
membrane; the procedure, which is effective in forming bifidobacterial protoplasts, destroys their iron transport mechanism
while uncovering surface iron-binding sites; and that such iron-binding sites may be of significance in the cellular iron
metabolism processes. 相似文献