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81.
82.
83.
Francisco Guillén Angel T. Martinez Maria Jesús Martínez 《Applied microbiology and biotechnology》1990,32(4):465-469
Summary Production of extracellular hydrogen peroxide by fungal oxidases is been investigated as a requirement for lignin degradation. Aryl-alcohol oxidase activity is described in extracellular liquid and mycelium ofPleurotus eryngii and studied under non-limiting nitrogen conditions. This aryl-alcohol oxidase catalyses conversion of primary aromatic alcohols to the corresponding aldehydes and H2O2, showing no activity with aliphatic and secondary aromatic alcohols. The enzyme is stable at pH 4.0–9.0, has maximal activity at 45°–50°C and pH 6.0–6.5, is inhibited by Ag+, Pb2+ and NaN3, and has aK
m
of 1.2 mM using veratryl alcohol as substrate. A single protein band with aryl-alcohol oxidase activity was found in zymograms of extracellular and intracellular crude enzyme preparations fromP. eryngii. 相似文献
84.
Walter Malorni Pietro L. Indovina Giuseppe Arancia Stefania Meschini Maria T. Santini 《In vitro cellular & developmental biology. Plant》1990,26(4):399-410
Summary This paper describes the microscopic evidence supporting a cesium-induced delay in the fusion of chick embryo myoblast membranes
during in vitro myogenic differentiation. We have recently demonstrated that the sharp decrease in the conductivity and permittivity
of the membranes of these myogenic cells at the time of fusion is delayed 30 h by the addition of cesium to the culture medium
(Santini et al., Biochim. Biophys. Acta 945:56–64; 1988). We report here that this delay in fusion is substantiated by direct
microscopic observation and that cesium also induces ultrastructural changes in the myoblast cells themselves. Possible mechanisms
by which cesium may cause both the delay in fusion as well as the ultrastructural changes observed are discussed.
This investigation was partially supported by an Italian Consiglio Nazionale delle Ricerche grant 85.00.304.02 (to P. L. I.). 相似文献
85.
Shlomo Nir Nejat Düzgünes Maria C. Pedroso De Lima Dick Hoekstra 《Cell biochemistry and biophysics》1990,17(2):181-201
The fusion of viruses with cells and liposomes is reviewed with focus on the analysis of the final extents and kinetics of
fusion.Influenza virus andSendai virus exhibit 100% of fusion capacity with cells at pH 5 and pH 7.5, respectively. On the other hand, there may be in certain
cases, a limit on the number of virions that can fuse with a single cell, that is significantly below the limit on binding.
It still remains to be resolved whether this limit reflects a limited number of possible fusion sites, or a saturation limit
on the amount of viral glycoproteins that can be incorporated in the cellular membrane, like the case of virus fusion with
pure phospholipid vesicles, in which the fusion products were shown to consist of a single virus and several liposomes. Both
viruses demonstrate incomplete fusion activity towards liposomes of a variety of compositions. In the case ofSendai virus, fusion inactive virions bind essentially irreversibly to liposomes. Yet, preliminary results revealed that such bound,
unfused virions can be released by sucrose gradient centrifugation. The separated unfused virions subsequently fuse when incubated
with a “fresh” batch of liposomes. We conclude, therefore, that the fraction of initially bound unfused virions does not consist
of dective particles, but rather of particles bound to liposomes via “inactive” sites.
Details of the low pH inactivation of fusion capacity ofinfluenza virus towards cells and liposomes are presented. This inactivation is caused by protonation and exposure of the hydrophobic
segment of HA2, and affects primarily the fusion rate constants. Some degree of inactivation also occurs when virions are bound to cellular
membranes. 相似文献
86.
In the course of three years' investigations (1983–1986) of Lake Volvi, N Greece, 62 species and varieties of chlorococcal algae and 6 species of ulotrichal algae (Chlorophyceae) were found. Although chlorophytes form the largest group of the phytoplankton assemblages of the lake, their biomass is relatively small or even negligeable in some periods of the year in comparison with domination cyanophytes, diatoms and cryptophytes. Morphological variation of diagnostic features is described and documented by original drawings in 53 taxa. 相似文献
87.
88.
Chromosomal polymorphism regarding number of NOR sites in the cyprinid fish Chondrostoma lusitanicum was examined using C-banding, silver-staining (Ag), and fluorescent staining with chromomycin A3 (CMA3). The analysis of heterochromatic regions allowed a more precise identification of the centromeric regions and the proposal of a revised haploid chromosome formula (7M: 15S: 3A). We describe variability in the number of NOR regions per genome, number of active NOR sites per cell, and relative size of individual NORs. Individuals expressed two or four NOR-bearing chromosomes. Polymorphism was detected in all the populations studied and sex-related differences were not found. The observed chromosomal NOR phenotypes suggest the occurrence of structural rearrangements during the evolutionary process of this diploid leuciscine cyprinid. 相似文献
89.
Humoral anti-idiotypic and anti-anti-idiotypic immune response in cancer patients treated with monoclonal antibody 17-1A 总被引:4,自引:0,他引:4
Peter Ragnhammar Maria Liljefors Anna-Lena Hjelm Håkan Mellstedt Jan-Erik Frödin J. Fagersberg 《Cancer immunology, immunotherapy : CII》1996,42(2):81-87
A group of 96 patients with advanced colorectal carcinoma were treated with the mouse (m) or chimeric (c) (mouse variable
regions × human IgG1 constant regions) monoclonal antibody (mAb) 17-1A recognizing the tumour-associated antigen GA733-2.
Eighty-two of the 83 patients treated with mmAb17-1A and 69% of the patients given cmAb17-1A (n = 13) developed anti-idiotypic antibodies (ab2). Auto-antibodies binding to tumour cells expressing GA733-2 were found in 7% of the patients. In a further 38 patients (40%)
antitumour-cell antibodies, i.e. anti-anti-idiotypic antibodies (ab3), were induced by the mAb17-1A therapy. Patients with detectable ab3 after treatment had significantly higher ab2 levels than those not developing ab3. Addition of granulocyte/macrophage-colony-stimulating factor (GM-CSF) to mmAb17-1A significantly enhanced the induction
of ab2 as well as induction of anti-anti-idiotypic antibodies (ab3), compared to mmAb17-1A alone. Patients with a high increase in antitumour-cell antibodies (ab3) induced by the therapy lived significantly longer than patients with no or a low level of induction of ab3 (P = 0.016). The results indicate that induction of an idiotypic network response might be an important effector mechanism in
mAb therapy.
Received: 20 October 1995 / Accepted: 18 December 1995 相似文献
90.
Maria de Fatima Bonaldo Pierre Jelenc Long Su Lee Lawton M. -T. Wu Dorothy Warburton Marcelo Bento Soares 《Human genetics》1996,97(4):441-452
A study was conducted on the feasibility of isolating genes and pseudogenes that map to chromosome 13 by a hybridization-based approach using a 13-specific library and pools of repeat-free cDNA clones. Five pairs of cDNA and chromosome 13 genomic clones were identified and characterized. Partial or full-length sequence was derived from all cDNAs, and database searches were performed for putative gene identification. Partial sequence was also obtained from the chromosome 13 genomic clones for comparison with those of the hybridizing cDNAs. As a result of these analyses we identified three genes, a putative homologue of a porcine mRNA encoding an unidentified hepatic protein, a putative homologue of a yeast integral membrane protein, and a gene for a translationally controlled tumor protein, and two processed pseudogenes, ribosomal proteins L23a and S3a. The latter was formerly identified as the v-fos transformation effector gene, Fte-1, and recently cited as a possible candidate for the BRCA2 gene on chromosome 13. All genes and pseudogenes were localized to cytogenetic bands by in situ hybridization of metaphase chromosomes with probes derived from the chromosome 13 genomic clones. 相似文献