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41.
42.
Characterization of Monoclonal Antibodies Specific for Erwinia carotovora subsp. atroseptica and Comparison of Serological Methods for Its Sensitive Detection on Potato Tubers 总被引:1,自引:0,他引:1 下载免费PDF全文
María Teresa Gorris Benito Alarcon María M. Lopez Mariano Cambra 《Applied microbiology》1994,60(6):2076-2085
Seven monoclonal antibodies (MAbs) to Erwinia carotovora subsp. atroseptica have been produced. One, called 4G4, reacted with high specificity for serogroup I of E. carotovora subsp. atroseptica, the most common serogroup on potato tubers in different serological assays. Eighty-six strains belonging to different E. carotovora subsp. atroseptica serogroups were assayed. Some strains of serogroup XXII also reacted positively. No cross-reactions were observed against other species of plant pathogenic bacteria or 162 saprophytic bacteria from potato tubers. Only one strain of E. chrysanthemi from potato cross-reacted. A comparison of several serological techniques to detect E. carotovora subsp. atroseptica on potato tubers was performed with MAb 4G4 or polyclonal antibodies. The organism was extracted directly from potato peels of artificially inoculated tubers by soaking or selective enrichment under anaerobiosis in a medium with polypectate. MAb 4G4 was able to detect specifically 240 E. carotovora subsp. atroseptica cells per ml by indirect immunofluorescence and immunofluorescence colony staining and after soaking by ELISA-DAS (double-antibody sandwich enzyme-linked immunosorbent assay) after enrichment. The same amount of cells was detected by using immunolectrotransfer with polyclonal antibodies, and E. carotovora subsp. atroseptica and subsp. carotovora were distinguished by the latter technique. ELISA-DAS using MAb 4G4 with an enrichment step also efficiently detected E. carotovora subsp. atroseptica in naturally infected tubers and plants. 相似文献
43.
Studies were undertaken on interactions between panicle size, insect density, host plant, and the environment for sorghum
head bug,Calocoris angustatus Lethiery on five sorghum genotypes in terms of bug population increase, grain damage and loss in grain mass across four panicle
sizes (5, 10 or 20 branches/panicle and whole panicle), and three infestation levels (5, 10 and 15 pairs of bugs/panicle).
Head bug numbers increased and grain damage decreased with an increase in panicle size in the head bug susceptible cultivars,
CSH 1 and CSH 5. However, the increase in bug numbers or decrease in grain damage was not significant in head bug resistant
genotypes, IS 17610 and IS 17645. Head bug numbers increased with an increase in infestation level in CSH 1 and CSH 5, however,
such an increase was not substantial in IS 17610 and IS 17645. Grain damage was significantly lower in IS 17610 and IS 17645
compared with CSH 1 and CSH 5 across infestation levels. Head bug population increased at a greater rate during the rainy
season compared with the dry season. Panicle size and infestation levels accounted for greater variation in grain damage and
percentage loss in grain mass during the rainy season than in the dry season. To identify reliable sources of resistance to
insects, it is important to study insect host plant-interactions across panicle sizes (levels of food availability), infestation
levels and seasons. 相似文献
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45.
Nucleocapsid-glycoprotein interactions required for assembly of alphaviruses. 总被引:30,自引:19,他引:11 下载免费PDF全文
We have studied interactions between nucleocapsids and glycoproteins required for budding of alphaviruses, using Ross River virus-Sindbis virus chimeras in which the nucleocapsid protein is derived from one virus and the envelope glycoproteins are derived from the second virus. A virus containing the Ross River virus genome in which the capsid protein had been replaced with that from Sindbis virus was almost nonviable. Nucleocapsids formed in normal numbers in the infected cell, but very little virus was released from the cell. There are 11 amino acid differences between Ross River virus and Sindbis virus in their 33-residue E2 cytoplasmic domains. Site-specific mutagenesis was used to change 9 of these 11 amino acids in the chimera from the Ross River virus to the Sindbis virus sequence in an attempt to adapt the E2 of the chimera to the nucleocapsid. The resulting mutant chimera grew 4 orders of magnitude better than the parental chimeric virus. This finding provides direct evidence for a sequence-specific interaction between the nucleocapsid and the E2 cytoplasmic domain during virus budding. The mutated chimeric virus readily gave rise to large-plaque variants that grew almost as well as Ross River virus, suggesting that additional single amino acid substitutions in the structural proteins can further enhance the interactions between the disparate capsid and the glycoproteins. Unexpectedly, change of E2 residue 394 from lysine (Ross River virus) to glutamic acid (Sindbis virus) was deleterious for the chimera, suggesting that in addition to its role in nucleocapsid-E2 interactions, the N-terminal part of the E2 cytoplasmic domain may be involved in glycoprotein-glycoprotein interactions required to assemble the glycoprotein spikes. The reciprocal chimera, Sindbis virus containing the Ross River virus capsid, also grew poorly. Suppressor mutations arose readily in this chimera, producing a virus that grew moderately well and that formed larger plaques. 相似文献
46.
A bifunctional protein in the folate biosynthetic pathway of Streptococcus pneumoniae with dihydroneopterin aldolase and hydroxymethyldihydropterin pyrophosphokinase activities. 总被引:2,自引:1,他引:1 下载免费PDF全文
A protein encoded by sulD, one of four genes in a previously cloned folate biosynthetic operon of Streptococcus pneumoniae, had been shown to harbor 6-hydroxymethyl-7,8-dihydropterin pyrophosphokinase activity. This SulD protein was purified and shown now to harbor also dihydroneopterin aldolase activity. The bifunctional protein therefore catalyzes two successive steps in folate biosynthesis. The aldolase activity can be ascribed to the N-terminal domain of the SulD polypeptide, and the pyrophosphokinase activity can be ascribed to the C-terminal domain. Homologs of the dihydroneopterin aldolase domain were identified in other species, in one of which the domain was encoded as a separate polypeptide. The native SulD protein is a trimer or tetramer of a 31-kDa subunit, and it dissociated reversibly after purification. Dihydroneopterin aldolase activity required the multimeric protein, whereas pyrophosphokinase was expressed by the monomeric form. With purified SulD, the amount of 6-hydroxymethyl-7,8-dihydropterin product formed by the aldolase was proportional to the fourth power of the enzyme concentration, as expected for a reversibly dissociating tetramer. By identifying the gene encoding dihydroneopterin aldolase, this work extends our understanding of the molecular basis of the folate biosynthetic system common to many organisms. 相似文献
47.
Estaras Matias Ortiz-Placin Candido Castillejo-Rufo Alba Fernandez-Bermejo Miguel Blanco Gerardo Mateos Jose M. Vara Daniel Gonzalez-Cordero Pedro L. Chamizo Sandra Lopez Diego Rojas Adela Jaen Isabel de Armas Noelia Salido Gines M. Iovanna Juan L. Santofimia-Castaño Patricia Gonzalez Antonio 《Journal of physiology and biochemistry》2023,79(1):235-249
Journal of Physiology and Biochemistry - We have investigated the effects of melatonin on major pathways related with cellular proliferation and energetic metabolism in pancreatic stellate cells.... 相似文献
48.
The immunogenicity of recombinant interleukin-2 (rIL-2, EuroCetus, Amsterdam, Netherlands) was studied in seventy-six patients receiving different subcutaneous immunotherapy regimens. Patients presented with progressive metastatic renal cell carcinoma, malignant melanoma, colorectal cancer, B-cell lymphoma, and Hodgkin's disease. An enzyme immunoassay (EIA) was employed to screen patients for development of non-neutralizing antibodies against rIL-2, antibody specificity was confirmed by a standard Western blot. Neutralizing serum activity against rIL-2 was detected using a standard CTLL mouse proliferation assay. Additionally, serum levels of soluble interleukin-2 receptors and lymphocyte subsets expressing the CD56 natural killer (NK) associated antigen were measured.In a proportion of approximately 35% to 90% of the patients treated, non-neutralizing antibodies against rIL-2 could be detected after all treatment courses were evaluated. Antibodies were of the IgG, IgM, IgA and IgD subtypes. None of the 76 patients exhibited serum neutralizing activity after one treatment course. Five patients exhibited neutralizing anti-rIL-2 serum activity after two or more treatment courses of systemic rIL-2. In three of these patients, antibodies neutralized both recombinant and natural IL-2. Patients developing neutralizing anti-rIL-2 antibodies, exhibited significantly lower serum sIL-2 receptor levels upon the emergence of serum neutralizing activity than patients without antibody. Additionally, NK cell associated CD56 positivity was significantly lower in patients who exhibited neutralizing anti-rIL-2 serum activity than in patients who did not. A significant decrease in levels of soluble IL-2 receptors and CD56 NK cell positivity was observed, when comparing values prior to and after onset of serum neutralizing activity against rIL-2. However, while emergence of neutralizing antibodies to rIL-2 diminished rIL-2 induced biological activation, it did not coincide with abrogation of treatment response.Abbreviations rIL-2
recombinant interleukin-2
- EIA
enzyme immuno assay
- rIFN-2
recombinant interferon- 2 相似文献
49.
50.
Olive mill wastewaters (OMW) are a by-product from olive oil manufacture that cause environmental pollution. These wastes have been used as substrate for the production of the extracellular polysaccharide xanthan by Xanthomonas campestris NRRL B1459-S4L41. Growth and xanthan production on dilute OMW as a sole source of nutrients were obtained at OMW concentrations below 60%, yielding a maximal xanthan production of 4.4gl−1 at 30–40% OMW concentration. Addition of nitrogen and/or salts led to significantly increased xanthan yields with a maximum of 7.7gl−1. The N/salts supplements also allowed an increase in the optimal OMW concentration. Inocula pre-grown on OMW can be used. Results suggest that an improved xanthan yield could be obtained with adequate balance between waste concentration and nitrogen or salt supplementation. OMW is proposed as a low-cost substrate for xanthan production with the additional environmental benefit of this use. 相似文献