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991.
B. Pérez-Vich J. Fernández R. Garcés J. M. Fernández-Martínez 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1999,98(3-4):496-501
Sunflower genotypes with increased levels of palmitic acid (C16 : 0) in the seed oil could be useful for food and industrial
applications. The objective of the present study was to determine the inheritance of the high C16 : 0 content in the sunflower
mutant line CAS-5 (>25% of the total oil fatty acids). This mutant was reciprocally crossed with the lines HA-89 (5.7% C16 : 0)
and BSD-2-691 (5.4% C16 : 0), the latter being the parental line from which CAS-5 was isolated. No maternal effect for the
C16 : 0 content was observed from the analysis of F1 seeds in any of the crosses. The inheritance study of the C16 : 0 content in F1, F2 and BC1F1 seeds from the crosses of CAS-5 with its parental line BSD-2-691 indicated that the segregation fitted a model of two alleles
at one locus with partial dominance for the low content. The analysis of the fatty acid composition in the F2 populations from the crosses with HA-89 revealed a segregation fitting a ratio 19 : 38 : 7 for low (<7.5%), middle (7.5–15%),
and high (>25%) C16 : 0 content, respectively. This segregation was explained on the basis of three loci (P1, P2, P3) each having two alleles showing partial dominance for low content. The genotypes with a high C16 : 0 content were homozygous
for the recessive allele p1 and for at least one of the other two recessive alleles, p2 or p3. This model was further confirmed with the analysis of the F3 and the BC1F1 generations. It was concluded that both the recessive alleles p2 and p3 were already present in the BSD-2-691 line, the allele p1 being the result of a mutation from P1. This genetic study will facilitate breeding strategies associated with the incorporation of the high C16 : 0 trait into
agronomically acceptable sunflower hybrids.
Received: 30 March 1998 / Accepted: 13 August 1998 相似文献
992.
The effect of soil nutrient availability on retranslocation of Ca,Mg and K from senescing sapwood in Atlantic white cedar 总被引:1,自引:0,他引:1
Nutrient resorption from senescing tissues increases plant nutrient-use efficiency, and may be an adaptation to nutrient limitation.
In some tree species, retranslocation of nutrients from sapwood during heartwood formation is a comparable process. We measured
Ca, Mg and K concentrations in Atlantic white cedar (Chamaecyparis thyoides) stemwood samples taken from two swamps in the
northeastern United States and compared them to soil mineral nutrient availability at each site. We found that Ca, Mg and
K concentrations were 60–700% higher in sapwood than in the immediately adjacent heartwood, indicating retranslocation of
these nutrients from senescing sapwood. Sapwood nutrient concentrations were similar between the two sites. However, nutrient
concentrations in the heartwood differed significantly between the sites, as did the relative degree of Ca and Mg retranslocation
from senescing sapwood. We found these differences between sites to be inversely related to significant differences in exchangeable
Ca, Mg and K as well as Al concentrations in the soil. These findings suggest that the degree of nutrient retranslocation
from senescing sapwood may be influenced by soil nutrient availability.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
993.
Influence of body composition on the metabolic rate of nestling European shags (Phalacrocorax aristotelis) 总被引:2,自引:0,他引:2
C. Bech J. E. Østnes 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1999,169(4-5):263-270
During the early development of avian nestlings, their mass-specific resting metabolic rate (RMR) changes in a biphasic pattern
with the peak value often being much higher than that expected for an adult bird of similar body mass. In the present study
we examined the possible influence of variations in the size of internal organs in “setting” the high RMR and peak metabolic
rate (PMR) during development in a large altricial species, the European shag (Phalacrocorax aristotelis). Thermoneutral RMR and cold-exposure induced PMR were measured in nestlings 15 days old, the age at which the highest RMR
occurred during development. Body mass averaged 414 g. Mean values of RMR and PMR were 5.75 W and 9.08 W, respectively; the
RMR value corresponds to approximately 250% of the expected value for an adult non-passerine bird of similar body mass. The
masses of all the organs measured (breast and leg muscles, heart, liver, intestine, and kidney) varied isometrically with
total body mass. However, large chicks had a significantly lower fractional water content than small chicks, suggesting that
the former had achieved a higher level of functional maturity. In contrast to what has been suggested for adult birds in general,
the heart and kidney masses of shag nestlings were not significantly correlated with the metabolic rates. The intestine length,
in contrast, was highly and positively correlated with both the RMR and the PMR, i.e. intestine length was a better predictor
of RMR and PMR than was total body mass. In addition, liver mass was positively correlated with RMR. The results of the present
study suggest that the liver in particular may play a key role in establishing the high, mass-specific RMR which is attained
during development in bird chicks. Our results also support previous suggestions that early in their development, altricial
chicks mainly allocate energy to the growth of `energy-processing' organs (such as the intestine and liver) rather than to
`energy-consuming' organs.
Accepted: 3 March 1999 相似文献
994.
A general concern for the conservation of endangered species is the maintenance of genetic variation within populations, particularly when they become isolated and reduced in size. Estimates of gene flow and effective population size are therefore important for any conservation initiative directed to the long-term persistence of a species in its natural habitat. In the present study, 10 microsatellite loci were used to assess the level of genetic variability among populations of the Komodo dragon Varanus komodoensis. Effective population size was calculated and gene flow estimates were compared with palaeogeographic data in order to assess the degree of vulnerability of four island populations. Rinca and Flores, currently separated by an isthmus of about 200 m, retained a high level of genetic diversity and showed a high degree of genetic similarity, with gene flow values close to one migrant per generation. The island of Komodo showed by far the highest levels of genetic divergence, and its allelic distinctiveness was considered of great importance in the maintenance of genetic variability within the species. A lack of distinct alleles and low levels of gene flow and genetic variability were found for the small population of Gili Motang island, which was identified as vulnerable to stochastic threats. Our results are potentially important for both the short- and long-term management of the Komodo dragon, and are critical in view of future re-introduction or augmentation in areas where the species is now extinct or depleted. 相似文献
995.
We studied genetic drift of mitochondrial DNA (mtDNA) haplotype frequencies in a natural population of red drum (Sciaenops ocellatus) from the northern Gulf of Mexico (Gulf). The amount of genetic drift observed across temporally adjacent year classes (1986–89) was used to estimate variance effective (female) population size (Nef). Nef was estimated to be 14 308 and the ratio of female effective size to adult female census size was approximately 0.004, which is among the lowest value reported for vertebrate animals. Low effective size relative to census size among red drum in the northern Gulf may result from yearly fluctuations in the number of breeding females, high variance in female reproductive success, or both. Despite low genetic effective size relative to census size, the genetic effective population size of red drum in the northern Gulf appears sufficiently large to preclude potentially deleterious effects of inbreeding. 相似文献
996.
997.
E. A. M. Schoffelmeer F. M. Klis J. H. Sietsma B. J. C. Cornelissen 《Fungal genetics and biology : FG & B》1999,27(2-3)
Sugar analysis of isolated cell walls from three formae speciales of Fusarium oxysporum showed that they contained not only glucose and (N-acetyl)-glucosamine, but also mannose, galactose, and uronic acids, presumably originating from cell wall glycoproteins. Cell wall glycoproteins accounted for 50–60% of the total mass of the wall. X-ray diffraction studies showed the presence of α-1,3-glucan in the alkali-soluble cell wall fraction and of β-1,3-glucan and chitin in the alkali-insoluble fraction. Electron microscopy and lectin binding studies indicated that glycoproteins form an external layer covering an inner layer composed of chitin and glucan. 相似文献
998.
Abstract. Structure, diversity and dynamics of five Japanese temperate old-growth forests were compared, differing from each other in, i.a., climate, dominant tree type, topography, disturbance regime. The forests were Aya, Ogawa, Kanumazawa Riparian, Kanumazawa upland and Senju. A permanent plot (1–6 ha) was established in each forest and trees were censused several times at intervals of two years. Mean annual recruitment rates and mortality rates in these forests were both in the range of 0.5 to 4.6 %/yr at the community level. Analyses of the structure and dynamics of populations showed that the underlying process was different among the forests. Some forests experienced compositional shifts in their canopies, others had a constant canopy composition but appeared to lack effective regeneration in recent years. The recruitment rate appeared to be strongly affected by competitive undergrowth vegetation such as dwarf bamboo which has been controlled by natural disturbance or human impact. It is likely that the forests with mostly low recruitment rates had a low species diversity. The current variation in structure, diversity and dynamics of the studied forests might have been determined not only by physical conditions (e.g. climate) but also by chance factors (e.g. disturbance, outbreak of deer population). 相似文献
999.
The effects of salinity on cell growth and docosahexaenoic acid (DHA) content of three marine microalgal strains, Crythecodinium cohnii ATCC 30556, C. cohnii ATCC 50051 and C. cohnii RJH were investigated. The lag phases of the three strains increased with increasing salinity in Porphyridium medium. The
specific growth rate of C. cohnii ATCC 30556 was the highest at 9 g L−1 NaCl while the other two strains had their highest specific growth rates at 5 g L−1 NaCl. The highest cell dry weight concentrations of 2.51 g L−1 and 1.56 g L−1 were achieved at 9 g L−1 NaCl for C. cohnii ATCC 30556 and ATCC 50051, respectively, while the highest dry weight concentration of 2.49 g L−1 was achieved at 5 g L−1 NaCl for C. cohnii RJH. The highest cell growth yield coefficient on glucose was 0.5 g g−1 for both C. cohnii ATCC 30556 and C. cohnii RJH and 0.45 g g−1 for C. cohnii ATCC 50051. All three strains responded to the change of salinity by modifying their cellular fatty acid compositions. At
9 g L−1 NaCl, C. cohnii ATCC 30556 had the highest total fatty acid content and DHA (C22:6) proportion. In contrast, C. cohnii ATCC 50051 and C. cohnii RJH had the highest DHA content at 5 g L−1 NaCl. C. cohnii ATCC 30556 and ATCC 50051 had the highest DHA yield (131.55 and 68.24 mg L−1 respectively) at 9 g L−1 NaCl while C. cohnii RJH had the highest DHA yield (128.83 mg L−1) at 5 g L−1 NaCl.
Received 27 May 1999/ Accepted in revised form 27 August 1999 相似文献
1000.
When barley ( Hordeum vulgare L. ) seedlings were treated with 100 mmol/L NaC1 for 2 d, the index of unsaturated fatty acid (IUFA) increased in the tonoplast vesicles that were isolated from the seedlings mots of two barley cultivars with different salt tolerance, whereas no change were observed when the seedlings were treated with exogenous fatty acids with different satumbility. Exogenous stearic acid and linoleic acid decreased Na + absorption and transportation to the shoots, increased K + absorption and transportation, decreased the leakage of electrolytes, and increased the phospholipid and galactose contents of lipids in tonoplast, enhanced the activities of tonoplast H+ -ATPase and H+ -PPase. This is consistent with the results that the two fatty acids, linoleic acid and stearic acid, regulate ion absorption and distribution, mitigate salt stress to some extent, the effects of linoleic acid being more the latter. 相似文献