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991.
Context-dependent changes in the perception of odor quality 总被引:3,自引:3,他引:0
Ambiguous odor compounds, partly citrus-like and partly woodyin odor character, were seen to change in odor quality whenevaluated in the same session as more prototypical odors. Whentested with characteristically citrus odors, the ambiguous compoundsseemed more woody, and when tested with characteristically woodyodors, the ambiguous odorants were higher in citrus character,an example of perceptual contrast. Response frequency biaseswere ruled out as an explanation for this shift by an experimentin which responses other than citrus and woody ratings wereasked of the subjects during the contextual exposure. Simplesensory adaptation was found to be a potential contributor tothe effect, and a sufficient condition to produce similar shiftsin odor quality. However, adaptation was not a necessary conditionto produce the effect. This was seen in reversed pair experimentsin which the contextual odors were presented after the ambiguousstimuli. The contextual shift was robustit was obtainedwith different ambiguous odors, contextual (conditioning) odors,numbers of contextual odors, orders of presentation of contextualodors relative to ambiguous odors, scale types, and rating tasksduring the presentation of contextual odors. 相似文献
992.
Harry Kotses Andrew Harver Joyce Segreto Kathleen D. Glaus Thomas L. Creer Gordon A. Young 《Applied psychophysiology and biofeedback》1991,16(1):1-21
We studied the effects of electromyographic biofeedback on measures of asthma severity in children. Fifteen children received biofeedback training to reduce facial tension, and 14 children, who served as controls, received biofeedback training to maintain facial tension at a stable level. Assignment to experimental condition was random. As a result of training, electromyographic levels decreased in children trained in facial relaxation and remained fairly constant in children trained in facial tension stability. Biofeedback training was augmented for children in both groups by having them practice their facial exercises at home. Each child's condition was followed for a five-month period subsequent to biofeedback training. Throughout the experiment, the following measures of asthma severity were monitored: lung function, self-rated asthma severity, medication usage, and frequency of asthma attacks. In addition, standardized measures of attitudes toward asthma, self-concept, and chronic anxiety were recorded at regular intervals. As compared to the facial stability subjects, the facial relaxation subjects exhibited higher pulmonary scores, more positive attitudes toward asthma, and lower chronic anxiety during the followup period. Subjects in the two groups, however, did not differ on self-rated asthma severity, medication usage, frequency of asthma attacks, or self-concept. Based on the improvements we observed in pulmonary, attitude, and anxiety measures, we concluded that biofeedback training for facial relaxation contributes to the self-control of asthma and would be a valuable addition to asthma self-management programs.This research was supported by NIH grant No. HL27402. We are grateful to Anita D. Baker, Lisa Barclay, Deborah L. Harm, and Douglas J. Miller for serving as experimenters and to Constance K. Cottrell and Cindy Stout for compiling summaries of the data. 相似文献
993.
Jonathan M. Mann C. Jean Babb Harry F. Hull Frederic D. Ball George W. Brown Richard S. Steece 《The Western journal of medicine》1984,141(3):339-341
Residential institutions for the mentally retarded are considered high-risk settings for hepatitis B (HB) infection. Accordingly, HB vaccine is recommended for susceptible clients and selected staff of such facilities. However, a serologic screening program among 364 residents of Los Lunas Hospital and Training School (LLHTS) in New Mexico found only 11 residents to be anti-HBc positive (3%) and only one of these residents was also HBsAg-positive (0.3%). The unexpectedly low prevalence of HB infections at LLHTS probably reflects infrequent HB introductions into the institution. Using these serologic data, a vaccination program was instituted to prevent HB infection among LLHTS residents, thereby eliminating the need for mass screening and HB vaccination of LLHTS employees. Serologic screening among residents of other smaller institutions for the mentally retarded is recommended before design of HB prevention programs for clients and staff. 相似文献
994.
Putrescine (a diamine) raises the thermal denaturation temperature of mononucleosomes but produces only minor changes in the overall shape of the thermal denaturation curve. This is similar to the effect of sodium ions and is consistent with nonspecific binding to the DNA of the nucleosome. At very low levels of spermidine or spermine the same simple rise in thermal denaturation temperature is seen but at higher levels (above 1 M for total spermidine concentration) the thermal denaturation curve becomes substantially sharper and the premelt region of the curve diminishes in area. The acetylspermidines display intermediate effects. The change in shape of the thermal denaturation curve was resolved into components (R1 and R2) due to mononucleosomes in their original conformation plus a component (T) induced by the presence of spermidine or spermine. The proportion of component T was substantially reduced with acetylspermidine, compared to equivalent concentrations of spermidine. Hence, we suggest that spermidine acetylationin vivo has the potential to partially destabilise the nucleosome structure, possibly in coordination with histone acetylation. 相似文献
995.
Factors affecting adventitious bud induction in Pinus elliottii (Engelm.) embryos cultured in vitro 总被引:4,自引:0,他引:4
Embryos of slash pine (Pinus elliottii Engelm.) were induced to form adventitious buds when placed in culture on nutrient media supplemented with cytokinin. Buds were induced on media containing Risser & White major salts. The high content in nitrogen of Murashige & Skoog formulation seems to be deleterious for this in vitro system, since morphogenic responses were only promoted when nitrogen concentration was drastically reduced in the macronutrient formulation. Factors such as concentration of cytokinin (6-benzyladenine) and time and method of exposure (liquid or solid induction medium) strongly influenced bud formation and development. The greatest number of buds and shoots were obtained from 22.0 M cytokinin, but these shoots showed less and slower development than those induced with low dosages of cytokinin. The presence of naphthaleneacetic acid in combination with cytokinin in the induction medium decreased the frequency of bud formation.Abbreviations (BA)
6-benzyladenine
- (NAA)
1-naphthaleneacetic acid 相似文献
996.
997.
Harry Walter Fatima A. Al-Romaihi Eugene J. Krob Geoffrey V. F. Seaman 《Cell biochemistry and biophysics》1987,10(3):217-232
The K-562 cell line is a culture of human leukemia stem cells originally derived from a patient with chronic myelogenous leukemia
in blast crisis. We have subjected such cells, in the log phase of growth, to countercurrent distribution in a charge-sensitive
dextran-polyethylene glycol aqueous-phase system, a method that fractionates cells on the basis of subtle differences in their
surface properties, and found that: (1) The cell population is heterogeneous since it is composed of cells with different
partition ratios. (2) There is a correlation between increasing cell partition ratios and increasing cell electrophoretic
mobilities. (3) Cells under different parts of the distribution curve have dissimilar ratios of cells in different parts of
the cell cycle, a phenomenon that may, at least partially, be the basis for the subfractionation of these cells. There is
a clear tendency for cells in G0+G1+early S to decrease and for those in late S+G2+M to increase with increasing partition ratios. (4) Sialic acid is a major surface charge component of the cells as evidenced
by a dramatic drop in their partition ratios after treatment with neuraminidase. 相似文献
998.
999.
Randall P. Niedz Sandra Schiller Smith Kerry B. Dunbar Christine T. Stephens Harry H. Murakishi 《Plant Cell, Tissue and Organ Culture》1989,18(3):313-319
Cotyledonary explants of 4-day-oldCucumis melo cv. Hale's Best Jumbo in vitro seedlings showed maximum initiation of shoot buds when cultured onto a revised Murashige & Skoog medium supplemented with 5 M indole-3-acetic acid and 5 M benzylaminopurine and cultured at 25–29°C under low light intensity (5–30 mol m-2 s-1). Subculture of the shoot buds onto the same medium without auxin and supplemented with 3 M benzylaminopurine caused the development of shoots from 30% of the buds. The presence of abscisic acid significantly increased the number of explants producing shoot buds. Bud initiation was affected by genotype, seedling age, light intensity, and temperature. Addition of gibberellic acid, thidiazuron or silver nitrate to regeneration medium did not improve either bud initiation or shoot regeneration. 相似文献
1000.
Graham Lloyd Jones Harry McLemore Edmundson David Wesche Allan Saul 《生物化学与生物物理学报:疾病的分子基础》1990,1096(1):33-40
There is a high prevalence of the erythrocyte polymorphism ovalocytosis associated with reduced susceptibility to malaria in Papua New Guinea. The major erythrocyte integral membrane protein, Band-3, showed markedly increased phosphorylation in whole cells or isolated ghosts from ovalocytic individuals. The cytoplasmic domain of the ovalocyte Band-3 was found to be approx. 3 kDa largen than the normocytic protein. The N-terminal sequence of the ovalocytic Band-3 was different from the reported sequence for human Band-3, suggesting that the increased size results from an N-terminal extension. Since this is the region of Band-3 which is phosphorylated and interacts with the red cell cytoskeleton, it is likely that this alteration in ovalocytic Band-3 is the underlying cause of the diverse alterations in ovalocytic cells including increased phosphorylation, increased membraned rigidity, decreased agglutinability by blood group antibodies and refractoriness to invasion by malarial parasites. 相似文献