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991.
Green cybrids with a new nucleus-chloroplast combination cannot be selected after protoplast fusion in the intersubfamilial Nicotiana-Solanum combination. As an approach to overcome the supposed plastomegenome incompatibility, a partial plastome transfer by genetic recombination has been considered. After fusions of protoplasts of a light-sensitive Nicotiana tabacum (tobacco) plastome mutant and lethally irradiated protoplasts of wild-type Solanum tuberosum (potato), a single green colony was recovered among 2.5×104 colonies. The regenerated plants had tobacco-like (although abnormal) morphology, but were normally green, and sensitive to tentoxin, demonstrating chloroplast markers of the potato parent. Restriction enzyme analysis of the chloroplast DNA (cpDNA) revealed recombinant, nonparental patterns. A comparison with physical maps of the parental cpDNA demonstrated the presence of a considerable part of the potato plastome flanked by tobacco-specific regions. This potacco plastome proved to be stable in backcross and backfusion experiments, and normally functional in the presence solely of N. tabacum nucleus. 相似文献
992.
Cooperation within Actin Filament in Vertebrate Skeletal Muscle 总被引:56,自引:0,他引:56
When actin molecules form “rigor complexes” with nucleotide-free myosin, tropomn binds calcium with greater affinity and in a cooperative response the remaining actin molecules not cornplexed with myosin are “turned on” even though calcium is absent. 相似文献
993.
994.
Fatigue is often reported after long duration flights. Mild hypobaric hypoxia caused by pressurisation may be involved in this effect through disruption of circadian rhythms, independently of the number of time zones crossed. In this controlled crossover study, we assessed the effects of two levels of hypoxia equivalent to 8000 and 12,000 ft on the circadian rhythm of plasma cortisol, a marker of the circadian time structure. Sixteen healthy young male volunteers (23-39 years) were exposed in a hypobaric chamber for 8 h (08:00-16:00 h) to 8000 ft, followed 4 weeks later to 12,000 ft. Plasma cortisol was assayed during two 24-h cycles (control and hypoxic exposure) every 2h in all subjects. We found a significant change in the pattern of cortisol secretion during both hypoxic exposures, with an initial fall in cortisol followed by a transient rebound, whereas the phase and the 24-h mean level remained unchanged. The change in cortisol pattern followed the alterations in autonomic balance assessed by heart rate variability (HRV) spectral analysis. The normalised high frequencies and the low-to-high frequencies ratio showed a significant shift toward sympathetic dominance with some differences in time course for both altitudes studied. HRV analysis improved the interpretation of cortisol 24-h profiles. Our data, which strongly suggest that prolonged mild hypoxia alters the expression of cortisol circadian rhythm, should be taken into account to interpret secretory rhythm changes after transmeridian flights. 相似文献
995.
Ae-Young Mo Bora Kwon Seralathan Kamala-Kannan Kui-Jae Lee Byung-Taek Oh Dae-Hyuk Kim Moon-Sik Yang Jin-Hyung Kim Seung-Moon Park 《World journal of microbiology & biotechnology》2010,26(6):1099-1105
Bacteria of the Bacillus species have been reported as an important microorganism in fermented soybean products. In the present study, thirty Bacillus isolates were screened from Meju, a Korean soybean fermentation starter. The comparative analysis of 16S rDNA sequences, 16S-23S internal transcribed spacer
sequences, phenotypic, and biochemical characterizations revealed three phylogenetically distinct groups namely Bacillus atrophaeus,
Bacillus polyfermenticus and Bacillus subtilis. The isolates were assayed for poly-γ-glutamate production and fibrinolytic activity. Among the isolates, B. polyfermenticus exhibited maximum poly-γ-glutamate production and fibrinolytic activity. Moreover, the soybean products fermented by B. polyfermenticus have increased the time taken for coagulation and hemorrhage in mice. The results of the present study clearly indicate the
functional role of B. polyfermenticus in fermented soybean products. 相似文献
996.
Genomewide association studies (GWAS) have proven a powerful hypothesis-free method to identify common disease-associated
variants. Even quite large GWAS, however, have only at best identified moderate proportions of the genetic variants contributing
to disease heritability. To provide cost-effective genotyping of common and rare variants to map the remaining heritability
and to fine-map established loci, the Immunochip Consortium has developed a 200,000 SNP chip that has been produced in very
large numbers for a fraction of the cost of GWAS chips. This chip provides a powerful tool for immunogenetics gene mapping. 相似文献
997.
Fernández-Acero FJ Jorge I Calvo E Vallejo I Carbú M Camafeita E Garrido C López JA Jorrin J Cantoral JM 《Archives of microbiology》2007,187(3):207-215
Botrytis cinerea is a phytopathogenic fungus causing disease in a substantial number of economically important crops. In an attempt to identify putative fungal virulence factors, the two-dimensional gel electrophoresis (2-DE) protein profile
from two B. cinerea strains differing in virulence and toxin production were compared. Protein extracts from fungal mycelium obtained by tissue
homogenization were analyzed. The mycelial 2-DE protein profile revealed the existence of qualitative and quantitative differences
between the analyzed strains. The lack of genomic data from B. cinerea required the use of peptide fragmentation data from MALDI-TOF/TOF and ESI ion trap for protein identification, resulting
in the identification of 27 protein spots. A significant number of spots were identified as malate dehydrogenase (MDH) and
glyceraldehyde-3-phosphate dehydrogenase (GAPDH). The different expression patterns revealed by some of the identified proteins
could be ascribed to differences in virulence between strains. Our results indicate that proteomic analysis are becoming an
important tool to be used as a starting point for identifying new pathogenicity factors, therapeutic targets and for basic
research on this plant pathogen in the postgenomic era. 相似文献
998.
Riccardo Montioli Carlotta Zamparelli Carla Borri Voltattorni Barbara Cellini 《The protein journal》2017,36(3):174-185
Human ornithine δ-aminotransferase (hOAT) (EC 2.6.1.13) is a mitochondrial pyridoxal 5′-phosphate (PLP)-dependent aminotransferase whose deficit is associated with gyrate atrophy, a rare autosomal recessive disorder causing progressive blindness and chorioretinal degeneration. Here, both the apo- and holo-form of recombinant hOAT were characterized by means of spectroscopic, kinetic, chromatographic and computational techniques. The results indicate that apo and holo-hOAT (a) show a similar tertiary structure, even if apo displays a more pronounced exposure of hydrophobic patches, (b) exhibit a tetrameric structure with a tetramer-dimer equilibrium dissociation constant about fivefold higher for the apoform with respect to the holoform, and (c) have apparent Tm values of 46 and 67?°C, respectively. Moreover, unlike holo-hOAT, apo-hOAT is prone to unfolding and aggregation under physiological conditions. We also identified Arg217 as an important hot-spot at the dimer–dimer interface of hOAT and demonstrated that the artificial dimeric variant R217A exhibits spectroscopic properties, Tm values and catalytic features similar to those of the tetrameric species. This finding indicates that the catalytic unit of hOAT is the dimer. However, under physiological conditions the apo-tetramer is slightly less prone to unfolding and aggregation than the apo-dimer. The possible implications of the data for the intracellular stability and regulation of hOAT are discussed. 相似文献
999.
Moose summer and winter diets along a large scale gradient of forage availability in southern Norway
Studies on dietary functional responses in large herbivores are traditionally conducted by following individual animals. The
method is very time-consuming, and hence, typically provides only a narrow array of forage species compositions. Here we use
a range level approach to look at moose (Alces alces) selectivity for and utilization of forage species in relation to availability in both summer and winter. We compare 12 Norwegian
ranges representing a large scale gradient in plant communities. The most important forage species in the diet were birches
(Betula spp., comprising 43% of all trees browsed in summer and 27% in winter), rowan (Sorbus aucuparia, 25% of trees browsed in summer, 37% in winter), and bilberry (Vaccinum myrtillus, 42% of herbaceous epidermal fragments in summer feces). Selectivity for birches was positively related to its availability
and negatively related to availability of rowan, Salix spp., and aspen (Populus tremula) together (all more selected for than birches). Multiple regression models including availability of several forage species
were thus superior to single-species models in explaining the diet content of main forage plants. Selectivity for birches
was also stronger in summer than in winter, while the opposite pattern was found for rowan. The finding is relevant for our
evaluation of the quality of summer and winter ranges, and hence, their relative influence on population productivity. Our
study underlines the need to incorporate species composition of available forage when quantifying dietary functional responses
in selective herbivores such as moose. Furthermore, care should be taken when extrapolating data on moose diet across ranges
or seasons. 相似文献
1000.
Leila M. Porter Sarah M. Sterr Paul A. Garber 《International journal of primatology》2007,28(5):1035-1058
We studied the diet, habitat use, and ranging behavior of 1 group of Callimico goeldii (callimicos) over 12 mo in northwestern Bolivia. The group’s diet was comprised of fungi (39%), fruits (31%), arthropods
(14%), exudates (14%), and other matter (2%). Callimicos concentrated their ranging activities in secondary forest (50%),
primary forest with dense understory (30%), and bamboo (17%) habitats. The group’s total home range was 114 ha; on average
they used 38.4 ha/ mo and had a day range of 925 m. Monthly average day ranges—but not monthly home ranges—increased as frugivory
declined, suggesting that subjects foraged on fungi and exudates by rechecking resources within a core area, making their
day ranges longer than during months when they concentrated on fruit resources. The callimicos formed polyspecific associations
with tamarins (Saguinus labiatus and S. fuscicollis) during 81% of observations. Day ranges increased in months with higher association rates which appears to result from the
callimicos using a broader set of habitats when with tamarins than when alone. The ranging pattern of callimicos appears to
be influenced primarily by 3 factors: their seasonal shift in diet requires that they forage in a variety of habitats across
the year; their depletion of resources causes them to shift their core area over time; and their lack of territorial behavior
eliminates the need to patrol boundaries as part of their daily movement. As a result, callimicos differ from many other callitrichids
in their low ratio of day range length to home range size. 相似文献