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1.
The rates of uptake by Alteromonas haloplanktis of 19 metabolizable compounds and by V. fischeri of 16 of 17 metabolizable compounds were negligible in the absence of added alkali-metal cations but rapid in the presence of Na. Only d-glucose uptake by V. fischeri occurred at a reasonable rate in the absence of alkali-metal cations, although the rate was further increased by added Na, K, or Li. Quantitative requirements for Na for the uptake of 11 metabolites by A. haloplanktis and of 6 metabolites by V. fischeri and the characteristics of the Na response at constant osmotic pressure varied with each metabolite and were different from the Na effects on the energy sources used. Li stimulated transport of some metabolites in the presence of suboptimal Na concentrations and for a few replaced Na for transport but functioned less effectively. K had a small capacity to stimulate lysine transport. The rate of transport of most of the compounds increased to a maximum at 50 to 300 mM Na, depending on the metabolite, and then decreased as the Na concentration was further increased. For a few metabolites, the rate of transport continued to increase in a biphasic manner as the Na concentration was increased to 500 mM. Concentrations of choline chloride equimolar to inhibitory concentrations of NaCl were either not inhibitory or appreciably less inhibitory than those of NaCl. All metabolites examined accumulated inside the cells against a gradient of unchanged metabolite in the presence of Na, even though some were very rapidly metabolized. The transport of l-alanine, succinate, and d-galactose into A. haloplanktis and of l-alanine and succinate into V. fischeri was inhibited essentially completely by the uncoupler 3,5,3',4'-tetrachlorosalicylanilide. Glucose uptake by V. fischeri was inhibited partially by 3,5,3',4'-tetrachlorosalicylanilide and also by arsenate and iodoacetate. 相似文献
2.
Determination by Gas Chromatography-Mass Spectrometry of [N(5)]Adenine Incorporation into Endogenous Cytokinins and the Effect of Tissue Age on Cytokinin Biosynthesis in Datura innoxia Crown Gall Tissue 下载免费PDF全文
In this study gas chromatographic-mass spectrometric techniques have been used to identify and quantify the metabolic incorporation of [15N5]adenine into zeatin and its metabolites by 3-week-old Datura innoxia Mill, crown gall tissue. In a parallel study the levels of endogenous cytokinins were also determined by the stable isotope dilution technique using deuterium (2H)-labeled internal standards. Incorporation levels of the [15N5]adenine after 8 hours of incubation, expressed as a percentage of the endogenous cytokinins, were as follows: zeatin (1.0%), zeatin riboside (1.5%), and zeatin riboside 5′-phosphate (10.2%). These results are consistent with those observed in complementary experiments using [U-14C]adenine, and support the proposal that the cytokinin biosynthesis occurs primarily at the nucleotide level. The effect of tissue age on cytokinin biosynthesis, determined by [U-14C]adenine incorporation into cytokinins by tissues at varying growth stages, indicated a steady increase with time reaching maximal synthesis at five weeks following subculture after which the level of 14C incorporation into cytokinins declined. 相似文献
3.
We have isolated the delta-globin gene of the New-World spider monkey,
Ateles geoffroyi, and compared its nucleotide sequence with those of other
primate delta- and beta-globin genes. Among primate delta-globin genes, the
rate of nonsynonymous substitutions is much less than the rate of
synonymous substitutions. This suggests that primate delta- globin genes
may remain under evolutionary conservation, perhaps because hemoglobin A2
has an as yet unknown physiological importance.
相似文献
4.
R I Macleod P J Hamilton J V Soames 《Analytical and quantitative cytology and histology / the International Academy of Cytology [and] American Society of Cytology》1988,10(3):176-180
A study was undertaken to ascertain if there were any morphometric or morphologic changes in exfoliated oral squames in either iron-deficiency or vitamin B12-deficiency states. The results revealed a significant (P less than .05) increase in nuclear area and a significant alteration in nuclear/cytoplasmic ratio in vitamin B12 deficiency; both returned to normal following replacement therapy. No changes were seen with iron deficiency anemia or non-vitamin B12 megaloblastic anemia. Ultrastructurally, the surface morphology showed similar features in all groups, with the plasma membrane forming complex folds (microplications) in three patterns: branching, parallel and network. The microplication widths and interplication distances were remarkably constant in both control and study groups, regardless of pattern. 相似文献
5.
6.
Biochemical pathways in prokaryotes can be traced backward through evolutionary time 总被引:10,自引:0,他引:10
For the first time, a credible prokaryotic phylogenetic tree is being
assembled by Woese and others using quantitative sequence analysis of
oligonucleotides in the highly conservative rRNA. This provides an
evolutionary scale against which the evolutionary steps that led to the
arrangement and regulation of contemporary biochemical pathways can be
measured. This paper presents an emerging evolutionary picture of aromatic
amino acid biosynthesis within a large superfamily assemblage of
prokaryotes that is sufficiently developed to illustrate a new perspective
that will be applicable to many other biochemical pathways.
相似文献
7.
Summary Five rates of limestone and 4 rates of fertilizers were used in a split-plot design to study their effects under field conditions
on Mo, Cu, B, Mn, and Zn levels in mixed forage tissue and soil, and on the forage yield. An increase in soil pH resulted
in an increase in Mo and Cu content of plant tissue while B, Mn, and Zn decreased. The micro-nutrient content of the tissue
increased as the harvesting season progressed. Increasing rates of applied fertilizer did not affect the micro-nutrient content
of the forage tissue or soil.
Liming to a pH of 5.6 and above reduced the availability of Mn and Zn in the soil. In general, the available B was low at
pH values greater than 6.1. Lime did not affect the quantities of Mo and Cu in the soil. Manganese is supplied in large quantities
by limestone and is not apt to be deficient in limed soil. However, addition of B and Zn may be required on the high pH soils
of Eastern Canada in future. Molybdenum was adequate where the soil was limed to a pH of 6.1 or greater.
The dry-matter yield of forage increased significantly with successive increases in lime up to pH 6.6 and with each increment
of fertilization.
Contribution No.226, Research Branch, Research Station, P.O. Box 1210, Charlottetown, P.E.I. and No.166, Experimental Farm, Nappan, N.S. 相似文献
8.
Summary Experiments were conducted to determine the influence of N, P, and K and of the NP and NK interactions on root yields and
tissue concentrations of N, P, and K of rutabagas grown on a sandy loam soil under greenhouse conditions. Root yields were
increased by applications of N and K but not by added P. The yield response to N was dependent on K supply. The highest dry
matter content in roots was associated with the lowest rates of N and K and the lowest root yields.
The N content of tissue at the early vegetative stage increased with increasing rates of N and decreased with increasing rates
of P and K. The N content of root tissue at harvest increased at the highest rates of N but was unaffected by rates of P and
K. The P and K content of root tissue increased with increasing rates of P and K, respectively.
The levels of nutrients in early vegetative tissue associated with optimum yields were about 2.6, 0.24, and 2.0% for N, P,
and K, respectively. The corresponding values in the leaf tissue at harvest were about 1.2, 0.12, and 1.5% N, P, and K, respectively.
Contribution No.222. 相似文献
9.
Selective esterification reactions of 1,6-anhydro-3-deoxy-β-D-xylo-hexopyranose(1), 1,6-anhydro-β-D-glucopyranose (7), and several derivatives of 7, were conducted with an acid chloride or acid anhydride in pyridine. Reaction of 1 with p-toluenesulfonyl chloride and with benzoyl chloride gave 70 and 63%, respectively, of the 2-esters. The 2-methyl and 2-benzyl ethers of 7, both having strongly hydrogen-bonded C-4 hydroxyl group, reacted with p-toluenesulfonyl chloride to yield the 4-monosulfonates (71 and 74%, respectively). Esterification of the 2-methyl ether and 2-p-toluenesulfonate of 7 with p-toluenesulfonic anhydride instead of with p-toluenesulfonyl chloride led to increased yields of the 4-p-toluenesulfonates after a shorter reaction-time. 相似文献
10.
A rapid sensitive method for the detection of viable bacterial cells is described in which P32 as inorganic orthophosphate is used to label the cells. Factors affecting the uptake of P32 by cells as well as the sensitivity of the method have been explored with suspensions of Aerobacter aerogenes. The uptake of P32O4 is dependent on several factors. Of various incubation media tested, one composed of 0.005 m KCl, 0.002 m MgSO4 and 10 mg/ml of glucose was found to best stimulate the uptake of the tracer. Incubation time and temperature and level of isotope and of unlabeled P also affected uptake. Labeled cells were collected on a membrane filter for measurement of radioactivity. Under optimal conditions, as few as 23 viable cells per milliliter were detected in 1 hr with 95% confidence. 相似文献