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1.
2.
Using divergent Giemsa staining protocols designed for other plant species, G-banding was visualized in the chromosomes of Allium cepa L., A. fistulosum L., and their interspecific (A. fistulosum × A. cepa) hybrid. This is the first demonstration of G-banding of Allium chromosomes. Differences and similarities with other Giemsa banding patterns in Allium are discussed. 相似文献
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4.
Glucoamylase overexpression inAspergillus niger: Molecular genetic analysis of strains containing multiple copies of theglaA gene 总被引:1,自引:0,他引:1
5.
Several screening methods at the so-called ready biodegradability level are suitable to test poorly soluble substances. Typical for these tests is that mineralization is evaluated from monitoring oxygen uptake or carbon dioxide production. Unfortunately, they suffer from a rather low precision in the calculated percentage of mineralization caused by subtracting a too high inoculum control measurement from the response in the test system. Criteria for blank oxygen consumption, due to the metabolic activity of the inoculum, are proposed from which maximum amounts of activated sludge or secondary effluent per litre test medium can be derived to be used as an appropriate inoculum. Both for current and future standardized tests the precision of the method can be kept within acceptable margins. Inoculum material was sampled from 40 communal biological waste water treatment plants. From endogenous respiration rates it was derived that the concentration of secondary effluent in the Closed Bottle Test can be increased up to 50 mL/L but that in respirometry tests inoculated with activated sludge the appropriate concentration is 10 mg/L dry matter or below, depending of the design of the test system.List of abbreviations BOD
biological oxygen demand
- CBT
Closed Bottle Test
- C
as
inoculum concentration in mg dry solids of activated sludge per litre test medium
- C
ef
inoculum concentration in ml secondary effluent per litre test medium
- C
ss
dry weight content of activated sludge (g/L)
- CFU
colony forming units
- DO7d
dissolved oxygen concentration (mg/L) after 7 days
- ISO
International Organization for Standardization
- NEN
Dutch Organization for Standardization
- O
c
oxygen capacity in mg oxygen per litre vessel volume
- OECD
Organisation for Economic Co-operation and Development
- Ox
as
oxygen consumption after one week in mg oxygen per mg dry weight activated sludge
- Ox
ef
oxygen consumption after one week in mg oxygen per mL secondary effluent
- Ox
ef
[n]
oxygen consumption after one week in mg oxygen per n mL secondary effluent
- Ox
flask
oxygen uptake in mg per litre flask volume
- RBT
Ready Biodegradability Test
- SLR
sludge loading rate in kg O2/kg dry weight·d
- ThOD
theoretical oxygen demand
- TPCBT
Two Phase Closed Bottle Test
- V
a
volumes of air and water per litre vessel
- V
w
volume, respectively
-
a
concentration of oxygen in air at 20° C and 101.5 kPa
-
s
saturation oxygen concentration in te aqueous phase 相似文献
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Marie-Jose de Smet Jaap Kingma Hans Wynberg Bernard Witholt 《Enzyme and microbial technology》1983,5(5):352-360
The bioconversion of hydrocarbons by Pseudomonas oleovorans has been studied in two-phase systems. In these systems, the hydrocarbon substrate is present in sufficient amounts to form the bulk apolar phase. High cell densities (up to 20 mg dry mass per ml water phase) are reached when the apolar phase consists of n-octane, 1-octene or 1-decene. There is considerable cell damage after incubation for 50–70 h. Loss of cell viability and membrane damage as observed by freeze-fracture electron microscopy correlate with a loss of hydrocarbon oxidation, measured as the conversion of 1-octene to 1,2-epoxyoctane. The final yield of oxidized hydrocarbon in the apolar substrate phase can be increased substantially by replacing the damaged cells with freshly grown cells. Yields up to 150 mg 1,2-epoxyoctane per ml 1-octene and up to 20–25 mg 1,2-epoxyoctane per ml culture were obtained with four cycles of the cell renewal procedure. Several other substrates in addition to octene were tested in the optimized two-phase system. Of these, 1-decene was converted into (R)-1,2-epoxydecane with an optical purity of 60%, while allylbenzene was converted into chiral 1,2-epoxy-3-phenylpropane. Some of the future applications of the conversion products are discussed. 相似文献
8.
Gerard J. Niemann Jos B. M. Pureveen Gert B. Eijkel Hendrik Poorter Jaap J. Boon 《Oecologia》1992,89(4):567-573
Summary Eleven grass species varying in potential relative growth rate (RGR) were investigated for differences in chemical composition by pyrolysis mass spectrometry. The spectral data revealed correlations between RGR and the relative composition of several biopolymers. Species with a low potential RGR contained relatively more cell wall material such as lignin, hemicellulose, cellulose, polysaccharide-bound ferulic acid and hydroxyproline-rich protein, whereas species with a high potential RGR showed relatively more cytoplasmic elements such as protein (other than those incorporated in cell walls) and sterols. 相似文献
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Analyses of successively collected fractions of phloem exudate of Yucca flaccida, and of Yucca fruits picked at various stages of growth, together with experiments on transpiration from fruits, have led to the following conclusions:
- 1 During fruit growth potassium, sodium, magnesium, phosphorus compounds, and nitrogenous substances are delivered to the fruit by both the xylem and the phloem. These solutes move also easily in radial direction between the xylem and phloem part of the vascular bundles. Actually they can be regarded as constituents of one stream of nutrients.
- 2 The overall efficiency of conversion of vascular-fluid dry matter into mature-fruit dry matter is approximately 61 %.
- 3 During its whole period of growth the fruit transpires an amount of water vapour of at least 6 times its own mature fresh weight.
- 4 Estimates could be made for the relative contributions of xylem and phloem in the delivery of fruit constituents. 18% of the water imported by the fruit during its growth had a phloem, 82 % a xylem origin; 89% is transpired, 11 % retained as a fruit constituent. At least 94 % of the dry matter, 69% of the potassium, 56% of the magnesium, 26% of the phosphorus, and 7% of the calcium of the average fruit have been delivered by the phloem. The translocation of nitrogenous substances occurs probably partly in a more indirect way with temporary storage in inflorescence parenchyma.