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141.
142.
Calcium in fungi 总被引:2,自引:0,他引:2
Abstract. Recently much experimental evidence has accumulated concerning intracellular calcium and its fundamental role as a regulator in eukaryotic cells. The literature relating to Ca2+ in fungi is large and diverse and this paper draws together the available information and discusses the particular functions of the ion in this group of organisms.
Uptake mechanisms in fungi are considered with special reference to the effect of Ca2+ on permeability and the systems responsible for transport of ions, sugars and amino acids. Discussion of the subcellular locations and distribution of Ca2+ is accompanied by a critique of methodology used in determination of subcellular sites of Ca2+ in fungi. The role of Ca2+ in morphogenesis in fungi is considered with particular reference to selected groups. 相似文献
Uptake mechanisms in fungi are considered with special reference to the effect of Ca
143.
Abstract A lignin substructure model, 1-(4-ethoxy-3,5-dimethoxyphenyl)-2-(4-ethoxy-3-methoxyphenyl)-propane-1,3-diol(I), was actively metabolized by a white-rot fungus Coriolus versicolor in low nitrogen stationary cultures favouring the ligninolytic activity in the fungus. Cleavage of the dimer I between Cα and Cβ of the propanoid side chain was the major degradative reaction by the fungus. 相似文献
144.
Fuensanta Reyes M.I. Perez-Leblic M.J. Martinez R. Lahoz 《FEMS microbiology letters》1984,24(2-3):281-283
Abstract Production of protoplasts in different genera of filamentous fungi with their own lytic enzymes obtained from autolyzed cultures, as well as the regeneration of these protoplasts, has been studied. The results support the idea that the use of these autolytic enzymes could be a general method of production of protoplasts from filamentous fungi. 相似文献
145.
Assessment of a model for intron RNA secondary structure relevant to RNA self-splicing--a review 总被引:36,自引:0,他引:36
A widespread class of introns is characterized by a particular RNA secondary structure, based upon four conserved nucleotide sequences. Among such "class I" introns are found the majority of introns in fungal mitochondrial genes and the self-splicing intron of the large ribosomal RNA of several species of Tetrahymena. A model of the RNA secondary structure, which must underlie the self-splicing activity, is here evaluated in the light of data on 16 further introns. The main body or "core structure" of the intron always consists of the base-paired regions P3 to P9 with the associated single-stranded loops, with P2 present also in most cases. Two minority sub-classes of core structure occur, one of which is typical of introns in fungal ribosomal RNA. Introns in which the core structure is close to the 5' splice site all have an internal guide sequence (IGS) which can pair with exon sequences adjacent to the 5' and 3' splice sites to align them precisely, as proposed by Davies et al. [Nature 300 (1982) 719-724]. In these cases, the internal guide model allows us to predict correctly the exact location of splice sites. All other introns probably use other mechanisms of alignment. This analysis provides strong support for the RNA splicing model which we have developed. 相似文献
146.
Thermophilic Humicola lanuginosa, Penicillium duponti, Sporotrichum thermophile and Mucor pusillus required succinate in addition to glucose for optimal growth. The requirement for succinate was concentration-dependent and the concentration needed for one half of the maximal growth was 6.14 mM. In the presence of succinate, glucose utilization from the medium was markedly increased and this was associated with increased levels of the enzymes of the glycolytic and Krebs cycle pathways. Addition of succinate to cultures growing in glucose at any stage of growth stimulated the growth with the resulting rate of growth remaining high if the addition was made within 3 days of inoculation. Cycloheximide (71.4 M) prevented the succinate-mediated derepression of the enzymes suggesting that succinate may remove the catabolite repression in the presence of glucose.A preliminary part of this work was presented at the 17th annual meeting of the Association of Microbiologists of India at Manipal (India) held from Dec. 13 to 15, 1976 相似文献
147.
T. K. Kirk E. Schultz W. J. Connors L. F. Lorenz J. G. Zeikus 《Archives of microbiology》1978,117(3):277-285
Culture parameters influencing metabolism of synthetic14C-lignins to14CO2 in defined media have been studied in shallow batch cultures of the ligninolytic wood-destroying HymenomycetePhanerochaete chrysosporium Burds. Study of the effect of O2 concentration in the gas phase above non-agitated cultures indicated essentially complete absence of attack on the lignin polymer at 5% O2 in N2, and a 2- to 3-fold enhancement by 100% O2 as compared to air (21% O2). Agitation of the cultures resulting in the formation of mycelial pellets greatly suppressed lignin decomposition. The optimum culture pH for lignin decomposition was 4 to 4.5, with marked suppression above 5.5 and below 3.5. The source of nutrient nitrogen (NO
3
–
, NH
4
+
, amino acids) had little influence on lignin decomposition, but the concentration of nitrogen was critical; decomposition at 24 mM was only 25–35% of that at 2.4 mM N. Thiamine was the only vitamin required for growth and lignin decomposition. Under the optimum conditions developed, decomposition of 5 mg of synthetic lignin was accompanied by utilization of approximately 100 mg of glucose. The influence of the various culture parameters was analogous for metabolism of synthetic lignin labeled in the ring-,side chain-, and methoxyl carbon atoms. 相似文献
148.
Previous research showed that addition of nutrient nitrogen to ligninolytic (stationary, nitrogen-starved) cultures of the wood-decomposing basidiomycete Phanerochaete chrysosporium causes a suppression of lignin degradation. The present study examined early effects on nitrogen metabolism that followed addition of NH
4
+
and l-glutamate at concentrations that yield similar patterns of suppression. Both nitrogenous compounds were rapidly assimilated (>80% in 6 h). Both caused an initial 80% or greater increase in the intracellular glutamate pool and had similar effects in increasing the specific activities of NADP- and NAD-glutamate dehydrogenases and glutamine synthetase. Differences between the effects of added NH
4
+
and glutamate showed that suppression was not correlated with intracellular pools of arginine or glutamine, nor was the maintenance of an elevated glutamate pool required to maintain the suppressed state. While a portion of the initial glutamate suppression could be attributed to an effect on central carbon metabolism through glutamate catabolism by NAD-glutamate dehydrogenase, the long term suppression by glutamate and the suppression by NH
4
+
were more specific. Suppression by NH
4
+
or glutamate in the presence or absence of protein synthesis (cycloheximide) followed essentially identical kinetics during 12 h. These results indicate that nitrogen additions cause a biochemical repression of enzymes associated with lignin degradation. Results are consistent with the hypothesis that nitrogen metabolism via glutamate plays a role in initiation of repression.Non-Standard Abbreviations DMS
2,2-dimethylsuccinate
- TCA
trichloroacetic acid 相似文献
149.
Hendrik C. Potgieter Nicolaas M.J. Vermeulen Daniel J.J. Potgieter Hein F. Strauss 《Phytochemistry》1977,16(11):1757-1759
An amino acid, lethal to New Hampshire chickens (LD50, 150 mg/kg) was isolated from dried sclerotia of the fungus Sclerotium rolfsii (Sacc.). Purification of the rather unstable compound was effected on a cation exchange column by means of displacement chromatography and the amino acid was crystallised from 80% methanol. A structure was assigned to the compound on the basis of available chemical and physical data, namely 2(S),3(R)-2- amino-3-hydroxypent-4-ynoic acid. Confirmation of this structure was gained by direct and indirect synthetic procedures. 相似文献
150.
A 13C-NMR study of the biosynthesis of dothistromin by Dothistroma pini was undertaken. The biosynthetic labelling pattern in this bistetrahydr 相似文献