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11.
MAAS FRANK M.; DE KOK LUIT J.; PETERS JANNY L.; KUIPER PIETER J. C. 《Journal of experimental botany》1987,38(9):1459-1469
Maas, F. M., De Kok, L. J., Peters, J. L. and Kuiper, P. J.C. 1987. A comparative study on the effects of H2S and SO2 fumigationon the growth and accumulation of sulphate and sulphydryl compoundsin Trifolium pratense L., Glycine max Merr. and Phaseolus vulgarisL.J. exp. Bot. 38: 1459-1469. The effects of 025 mm3 dm3 H2S and SO2 on growth andsulphur content of shoots of Trifolium pratense, Glycine maxand Phaseolus vulgaris were studied. After 2 weeks of fumigationthe yield of T. pralense was reduced by 32% by H2S, but notaffected by SO2. Yield of G. max was not affected by H2S, butreduced by 20% by SO2, whereas that of P. vulgaris was increasedby 11% by H2S and not affected by SO2. Increases in sulphydrylcontent were already observed after 24 h of exposure to H2Sand SO2 in all plants. The increase was greatest in T. pratenseand smallest in P. vulgaris and, except for T. pratense, alwaysgreater in the H2S-exposed than the SO2-exposed plants. Oneday of exposure resulted in an increase in sulphate contentonly in the SO2-fumigated plants, with the highest accumulationin T. pratense and the lowest in P. vulgaris. After 2 weeksan increase in sulphate content was also observed in the H2S-exposedplants. This increase was also highest in T. pratense and lowestin P. vulgaris. Transpiration rate was not affected by a 24 h exposure to H2Sor SO2 and was highest in T. pratense, intermediate in G. maxand lowest in P. vulgaris. The order of theoretical rates of deposition of H2S and SO2correlated with the observed increases in sulphydryl contentduring the first 24 h of exposure in both H2S and SO2-fumigatedplants and with the increase in sulphate content in the SO2-exposedplants. The increases in sulphydryl content were only 8% ofthe theoretical H2S and SO2-deposition fluxes, whereas sulphateaccumulation accounted for at least 57% of the theoretical SO2-depositionflux. Key words: Air pollution, clover, French bean, Glutathione, Soybean, sulphur metabolism. 相似文献
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13.
Dr. John L. Johnson Carol Phelps Lisa Barroso Mary D. Roberts David M. Lyerly Tracy D. Wilkins 《Current microbiology》1990,20(6):397-401
Results from our cloning studies on toxin A indicated that the gene for toxin B resided approximately 1 kb upstream of the toxin A gene. Clone pCD19, which contains the 5-end of the toxin A gene and a small open reading frame, was found to contain 1.2 kb of DNA which, when subcloned, expressed a nontoxic peptide that reacted with toxin B antibodies. The rest of the toxin B gene was located on the 6.8 kb cloned fragment of plasmid pCD19L. The two fragments overlapped 0.8 kb. Lysates containing protein expressed by the 6.8 fragment were cytotoxic and lethal, and were neutralized by toxin B antibody. The two fragments were ligated to give the complete toxin B gene. The protein expressed by the complete gene was cytotoxic and lethal, and showed complete immunological identity with toxin B. Further analysis of the expressed protein and the toxin B gene confirmed our earlier findings showing that toxin B has a molecular weight of 240,000 or greater. 相似文献
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15.
REINDERS J. E. A.; AS H. VAN; SCHAAFSMA T. J.; DE JAGER P. A.; SHERIFF D. W. 《Journal of experimental botany》1988,39(9):1199-1210
In this paper we demonstrate the study of plant water balanceby the non-invasive measurement of tissue water content andwater flow using proton nuclear magnetic resonance (NMR). Sapvelocity and flux were measured independently in the presenceof an excess of stationary tissue water. The instrumentationdescribed allows automated and unattended measurement of flow-and water content-variables in a well-defined region of theplant over periods of several days, with a time resolution betweensuccessive measurements of c. 5 s. Using this apparatus theeffect of changes in light intensity (day/night rhythm) andrelative humidity on stem tissue water content as well as onthe velocity and flux of xylem sap in the stem were investigatedin a cucumber plant. The results are in agreement with predictionsfrom a simple model for plant water balance, which is basedon water potential, flow rate and resistance to flow. As longas only transpiration is varied, flow rate and water content(or potential) are affected in opposite ways as demonstratedin this paper. In contrast, the model predicts that changesin uptake (resulting from changes in, for example, root resistance)will induce changes in water content and flow in the same direction.An experimental verification of this prediction is given ina subsequent paper, where, in addition, the NMR results arecompared to those obtained with a dendrometer. Key words: Water balance model, Cucumis sativus L., flow, water content, NMR, water balance measurement 相似文献
16.
Stomatal Response of some Cultivated and Wild Tuber-bearing Potatoes in Warm Tropics as Influenced by Water Deficits 总被引:1,自引:0,他引:1
Leaf resistances of 14 cultivated potato genotypes (Solanumspp) and three tuber-bearing wild Solanum species were comparedwhen plants were grown under water stress at two tropical sitesFactors investigated were diurnal changes in leaf resistance,the effect of plant age, transient drought versus well-wateredconditions of potted and field-grown plants These measurementswere carried out in order to determine the stomatal behaviourof tuber-bearing genotypes and species Significant genotypic differences in leaf resistances were notedwithin the cultivated genotypes All genotypes had higher resistanceswhen water-stressed, but LT-7 appeared to have the lowest leafresistances Genetic differences in stomatal behaviour of tuber-bearingSolanum species were confirmed Abaxial stomatal resistancesof water-stressed plants of the species ranged between 1 74and 13 8 s cm1 Stomata of S chacoense were less affectedby drought (three-fold) than S tuberosum (four-fold) The greatesteffect was on S jungasense (five-fold) and on S raphanifoliumThese data show that stomata behaviour among tuber-bearing Solanumspecies is sufficiently different to warrant investigationsof drought-resistance in potato species under dry hot conditions Solanum tuberosum L., Solanum raphanifolium, Solanum chacoense, Solanum jungasense, leaf resistance 相似文献
17.
A New Procedure for the Calculation of Oxygen Diffusion Resistance in Legume Nodules from Flow-through Gas Analysis Data 总被引:1,自引:0,他引:1
MINCHIN F. R.; IANNETTA P. P. M.; FERNANDEZ-PASCUAL M.; DE LORENZO C.; WITTY J. F.; SPRENT J. I. 《Annals of botany》1992,70(3):283-289
Plants of white lupin (Lupinus albus L cv Multolupa) and soyabean(Glycine max L cv Clarke) were grown in controlled-environmentcabinets, subjected to various stresses and their nodular nitrogenaseactivity and total root respiration measured When these measurementswere used to calculate nodular oxygen diffusion resistance,using a simplified equation for Fick's first law of diffusion,it was found that the apparent resistance of stressed nodulesincreased anomalously with decreases in external oxygen concentrationA new analysis procedure is proposed to alleviate this anomalyThis procedure also uses the simplified Fick's law equationbut includes a respiratory contribution to the total oxygenflux across the diffusion barrier which is not coupled to nitrogenaseactivity Also, resistance is modelled as an exponential functionof external oxygen concentration Use of this analysis procedureproduces realistic values for total resistance and providesa characterisation of this resistance into a minimum value andan adjustment factor for changes in external oxygen It is postulatedthat the additional respiration component represents the activityof nodule cortex cells involved in the diffusion barrier, particularlythat of vascular bundles Oxygen diffusion resistance, nodule, nitrogen fixation, respiration 相似文献
18.
An experimental test of the eddy correlation technique over a Mediterranean macchia canopy 总被引:4,自引:1,他引:3
R. VALENTINI G. E. SCARASCIA MUGNOZZA P. DE ANGELLS R. BIMBI 《Plant, cell & environment》1991,14(9):987-994
Abstract. Flux densities of water vapour and carbon dioxide were measured for a Mediterranean macchia canopy. Results show good agreement between the measured available energy and the sum of latent sensible and heat flux densities determined with the eddy correlation technique. Joint evaluation of the Bowen ratio, aerodynamic resistance, canopy resistance and the 'omega factor' suggests that the macchia canopy is intermediate in aerodynamic roughness between coniferous and deciduous canopies. Maximum daytime carbon flux densities ranged from -14 to -22(μnol m−2 s−1 on a ground area basis. The ratio of transpiration to assimilation (E/A) was a function of incident photo-synthetic photon flux density below about 400 μmol m−2 s−1 and above it was fairly constant at 272 mol mol−1 (H2 O/CO2 ). The relationship between carbon influx and canopy conductance was linear. Results show promising applications of the eddy correlation technique for evaluating physiological features of canopies, treated as unitary functional systems. 相似文献
19.
Chloramphenicol acetyl transferase (CAT) gene was used as a reporter gene to assess the conditions for polyethylene glycol (PEG)-mediated transfection of kiwifruit protoplasts. The effect of plasmid concentration and the presence of carrier DNA were each assessed by analysing CAT activity in transfected protoplasts using thin-layer chromatography (TLC) autoradiographic detection of acetylated chloramphenicol. A gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS) non-radioactive method was developed for monitoring CAT gene activity. This method provides a high speed of analysis (30 min) and precise means of detecting acetylated products at the nanomolar level, enabling quantification at very low transfection rates. Using this method we optimized plasmid and PEG concentration and also assessed the effect of heat shock on transfection. The best CAT activity was obtained using 30% polyethylene glycol 4000 and by submitting protoplasts to heat shock (45 °C, 5 min) prior to transfection. 相似文献
20.
Wolterbeek, H. Th. and De Bruin, M. 1986. Xylem and phloem importof Na+, K+ , Rb+, Cs+ and in tomato fruits: differential contributions from stem and leaf.J.exp. Bot. 37: 928939. The transport of Na+, K+, Rb+, Cs+ and into developing fruits of tomato (an inbred lineof Lycopersicon esculentum Mill. cv. Tiny Tim) was measured.Element solutions were introduced into the transpiration streamthrough the cut stem bases of plant parts consisting of a stempart with single green fruit, both with and without attachedfully expanded leaf. Measurements were carried out of the accumulationin the fruit of the gamma-ray emitting radiotracers 24Na+, 42K+,86Rb+, 134Cs+ and The transport into the fruit was expressed by a single parameter taking intoaccount volume flows varying with time and experiments. Xylemto phloem transfer in the stem as a source of fruit elementsupply was shown to be inversely related with the velocity offlow of the stem xylem. The results also indicated that thetransfer system in the stem was more rapidly equilibrated thanit was in the leaf. Stem loading of the phloem is suggested as a possible mechanismregulating the solute influx in fruits under varying flow velocitiesof the stem xylem, while fruit influx of phloem solutes, whichwere loaded in the leaf, may play a major role in influx regulationunder conditions of varying solute concentrations. Key words: Alkali ions, tomato fruits, stem and leaf phloem loading 相似文献