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991.
Effect of nitrogen supply on frost resistance, nitrogen metabolism and carbohydrate content in white clover (Trifolium repens) 总被引:1,自引:0,他引:1
Nina Sandli Mette M. Svenning Kirsti Røsnes Olavi Junttila 《Physiologia plantarum》1993,88(4):661-667
Effects of mineral nitrogen (2, 4, 6 and 8 m M NH4 NO3 ) and nodulation with Rhizobium on frost hardiness in seedlings of white clover ( Trifolium repens ) have been studied. Seedlings of a population from Bodø (67°N lat.) were grown in Leonard jars under controlled conditions in a phytotron. For induction of frost hardening, plants were first exposed to 12 h photoperiod conditions for 2 weeks at 18°C, then for 2 weeks at 6°C and finally for 2 weeks at 0.5°C. Frost hardiness after treatments at 6 and 0.5°C was significantly enhanced by increasing nitrogen supply and was positively correlated with total nitrogen content of the stolons. Frost hardiness of nodulated plants correlated to the tissue nitrogen concentration. Content of soluble proteins in stolons decreased during hardening at 6°C but did not change during treatment at 0.5°C. There were minor changes in total amount of free amino acids during hardening. Both absolute and relative amounts of proline and arginine increased, and those of asparagine decreased during hardening. Absolute amounts of all free amino acids increased with increasing nitrogen supply, but the changes during hardening were similar in all treatments. There was a significant increase in the content of soluble carbohydrates during hardening. However, this increase was inversely related to nitrogen supply. 相似文献
992.
Defining phosphorus efficiency in plants 总被引:6,自引:0,他引:6
The many different definitions for "nutrient efficiency" make the use of the term ambiguous. We evaluated nutrient efficiency using data from a study of response to phosphorus (P) supply in white clover (Trifolium repens L.) and lucerne (Medicago sativa L.). Application of various criteria identified in the literature as measures of nutrient efficiency did not clarify differences between purportedly P efficient and inefficient germplasm. Germplasm differed in maximum shoot and total dry mass and in solution P concentration ([P]s) required to achieve 80% maximum yield, but not in P concentration of tissue ([P]t), internal P utilization, or P uptake per unit of fine root dry mass. Differences in yield may have resulted from factors other than efficient use of P. To reduce the confounding effects that other factors have on nutrient efficiency, it is essential that equivalent yields of germplasm be demonstrated where nutrients are not limiting. Mechanisms that enable enhanced nutrient efficiency can be identified less ambiguously using this approach.Joint contribution of the Minn. Agric. Exp. Stn. and the USDA-ARS 相似文献
993.
Nitrogen losses in puddled soils as affected by timing of water deficit and nitrogen fertilization 总被引:2,自引:0,他引:2
Erratic rainfall in rainfed lowlands and inadequate water supply in irrigated lowlands can results in alternate soil drying and flooding during a rice (Oryza sativa L.) cropping period. Effects of alternate soil drying and flooding on N loss by nitrification-denitrification have been inconsistent in previous field research. To determine the effects of water deficit and urea timing on soil NO3 and NH4, floodwater NO3, and N loss from added 15N-labeled urea, a field experiment was conducted for 2 yr on an Andaqueptic Haplaquoll in the Philippines. Water regimes were continuously flooded, not irrigated from 15 to 35 d after transplanting (DT), or not irrigated from 41 to 63 DT. The nitrogen treatments in factorial combination with water regimes were no applied N and 80 kg urea-N ha–1, either applied half basally and half at 37 DT or half at 11 DT and half at 65 DT. Water deficit at 15 to 35 DT and 41 to 63 DT, compared with continuous soil flooding, significantly reduced extractable NH4 in the top 30-cm soil layer and resulted in significant but small (<1.0 kg N ha–1) soil NO3 accumulations. Soil NO3, which accumulated during the water deficit, rapidly disappeared after reflooding. Water deficit at 15 to 35 DT, unlike that at 41 to 63 DT, increased the gaseous loss of added urea N as determined from unrecovered 15N in 15N balances. The results indicate that application of urea to young rice in saturated or flooded soil results in large, rapid losses of N (mean = 35% of applied N), presumably by NH3 volatilization. Subsequent soil drying and flooding during the vegetative growth phase can result in additional N loss (mean = 14% of applied N), presumably by nitrification-denitrification. This additional N loss due to soil drying and flooding decreases with increasing crop age, apparently because of increased competition by rice with soil microorganisms for NH4 and NO3. 相似文献
994.
The long-term effects of biological agents alone and in combination with monoammonium phosphate on tree growth and fruit production
of apple trees planted on apple replant soil was studied for five years. Application of monoammonium phosphate (MAP) in the
year of planting increased shoot growth, cross-sectional trunk area and fruit yield of McIntosh on M.26 rootstock for the
first two years. The application of bacterial agents alone were not effective in increasing young tree growth except BACT-1
in 1987. None of the bacterial agents increased fruit yield when applied alone. The addition of certain bacterial agents to
MAP application increased young tree growth in various years. The combination of bacterial agent B-10 and MAP reduced young
tree growth and yield compared with the MAP treatment alone. These results suggest that the application of MAP alone may be
sufficient to alleviate the replant problem and the addition of BACT-1, EBW-4 or B8 bacterial agents to this treatment may
be beneficial to increase tree growth in some years.
Contribution number 822.
Contribution number 822. 相似文献
995.
E. Zebe G. Gäde 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1993,163(2):107-112
Metabolite concentrations in flight muscles and in abdomen of beetles (Pachnoda sinuata) were measured after various periods of tethered flight and subsequent rest. Three distinct phases of energy metabolism are found in active flight muscles: (1) during the first minutes of flight proline is used as main substrate and concomitantly alanine accumulated as an end product; (2) the second phase is characterized by a large-scale degradation of glycogen; (3) after about 8 min of flight the metabolite levels stabilize, while flight performance appears unchanged. After the termination of flight the preflight proline concentration (70 mol·g-1 fw) is re-established in less than 60 min, whereas restoration of resting levels of other metabolites requires longer. The pattern of maximal enzyme activities and the respiratory rates of mitochondria with different substrates confirm the significance of proline and carbohydrates as the main fuels of working flight muscles.Abbreviations CS
citrate synthetase
- Cytox
cytochrome c oxidase
- EDTA
ethylenediaminetetra-acetate
- fw
fresh weight
- GluDH
glutamate dehydrogenase
- GPT
alanine aminotransferase
- HOAD
hydroxyacyl-coenzyme A dehydrogenase
- HPLC
high pressure liquid chromatography
- ME
malic enzyme
- PCA
perchloric acid
- RQ
repiratory quotient
- TRA
triethanolamine 相似文献
996.
F. León-Velarde J. Sanchez A. X. Bigard A. Brunet C. Lesty C. Monge-C 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1993,163(1):52-58
Capillarity, fibre types, fibre area and enzyme activities of different skeletal muscles (pectoralis, extensor digitorum longus), tibialis anterior, plantaris and the myocardium were compared in Andean coot (Fulica americana peruviana) native to high altitude (Junín, Perú, 4200 m) and the same species nesting at sea level. Numbers of capillaries per square millimeter were higher in all high-altitude muscles when compared with sea-level muscles (P<0.0001). Moreover, values for capillaries per fibre and capillaries in contact with each fibre were higher in digitorum and tibialis high-altitude muscles. Muscle fibres were classified as Type I, Type IIA or Type IIB on the basis of their myofibrillar ATPase pH lability. Pectoralis muscle of high-altitude and sea-level coots presented only fibres of Type IIA. In contrast, all the leg muscles studied showed a mosaic pattern of the three fibre types. Fibre areas were determined using a Leitz Texture Analysis System. Significant differences in fibre area were observed (P<0.01) between high-altitude and sea-level muscles. Mean muscle fibre diameters were also lower in the high-altitude group than in the sea-level group. The enzyme activities studied were hexokinase, lactate dehydrogenase, citrate synthase and 3-hydroxyacyl-CoA-dehydrogenase. The oxidative capacity, as reflected by citrate synthetase and hydroxyacyl-CoA-dehydrogenase activities, was greater for myocardial and pectoralis than for leg muscles. However, analysis of maximal enzyme activities showed that there were no significant differences between the glycolytic and oxidative enzyme activities of high-altitude and sea-level coots. These results suggest that in Andean coots genetically adapted to high altitude, changes in muscle capillarity and fibre size, in addition to high haemoglobin O2 affinity and low haemoglobin concentration, are sufficient to allow adequate energy production without increases in enzymatic activities.Abbreviations BSA
bovine serum albumin
- C:F ratio
Capillaries per fibre
- CAF
Capillaries in contact with each fibre
- CD
capillary density (mm-2)
- CS
citrate synthetase
- EDL
muscularis digitorum longus
- fra
fraction reduction area
- HA
high altitude
- HAD
hydroxyacyl-CoA-dehydrogenase
- HK
hexokinase
- LDH
lactate dehydrogenase
-
P
50
PO2 at which hemoglobin is half saturated with O2
-
P
aO2
arterial partial pressure of oxygen
- PAS
periodic acid-schiff
- PEC
muscularis pectoralis
- PLA
muscularis planaris
-
P
tO2
mean tissue oxygen pressure
-
P
vO2
mixed venous partial pressure of oxygen
- SD
standard deviation
- SL
sea level
- TA
muscularis tibialis anterior
- TAS
texture analysis system 相似文献
997.
J. L. Albi J. Planas J. Sánchez 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1993,163(2):118-122
Glucose metabolism in peripheral blood lymphocytes from the brown trout Salmo trutta has been studied. Glucose is taken up by means of a sodium-independent saturable process (K
m=10.8 mmol·l-1), as well as by simple diffusion. Once within the cell, most of glucose is directed to lactate production through either the Embden-Meyerhof pathway or the hexose-monophosphate shunt. Rates of lactate formation are higher than rates of CO2 formation. Glutamine does not exert an effect on either glucose uptake or glucose metabolism. The present study provides information regarding the nature of energy sources for different cell types in salmonids.Abbreviations 3-OMG
3-O-methyl glucose
- EM
Embden-Meyerhoff pathway
- G6D
glucose-6-phosphate dehydrogenase
- HK
hexokinase
- HMS
hexose monophosphate shunt
- ICDH
isocitrate dehydrogenase
-
K
m
apparent Michaelis constant
- LDH
lactate dehydrogenase
- MCB
modified Cortland buffer
- PBL
peripheral blood lymphocytes
- PFK
fructose-6-phosphate kinase
- PK
pyruvate kinase
- RBC
red blood cells
-
V
max
maximal rate of uptake 相似文献
998.
S. H. Ogo C. F. Bernardes M. L. Glass M. A. Torsoni A. E. Vercesi 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1993,163(7):614-619
Digitonin was applied to permeabilize the plasma membrane of Bothrops alternatus erythrocytes to study respiration, oxidative phosphorylation and Ca2+ transport by mitochondria in situ. These mitochondria oxidized added NAD-linked substrates, succinate and N,N,N, N-tetramethyl-p-phenylenediamine. Respiration was sensitive to rotenone and cyanide but not to antimycin A. This indicates that Bothrops mitochondria possess the respiratory complexes NADH-ubiquinone, succinate-ubiquinone, and ferrocytochrome c-oxygen oxidoreductases, although the lack of sensitivity to antimycin A raises doubt about the composition of the ubiquinol cytochrome c-reductase complex. An ability to build up and sustain a membrane potential was documented by their capacity to accumulate tetraphenylphosphonium and Ca2+ through an uncoupler-sensitive mechanism. Addition of ADP caused a transient decrease in the membrane potential, indicating that this is the predominant driving force for ATP synthesis as in most types of mitochondria. Uncoupling of phosphorylation from the oxidative process increased hemoglobin O2 affinity, which suggests that ATP production by mitochondria may participate in modulation of O2 transport by hemoglobin.Abbreviations
membrane potential
- BAE
Bothrops alternatus erythrocytes
- DNP
2,4-dinitrophenol
- DPG
2,3-diphosphoglycerate
- EGTA
ethyleneglycol tetra-acetic acid
- FCCP
carbonylcyanide p-trifloromethoxyphenylhydrazone
- TMPD
N,N,N,N-tetramethyl-p-phenylenediamine
- TPP+
tetraphenylphosphonium
- TRIS
tris-(hydroxymethyl)aminomethane 相似文献
999.
W. -M. Weber B. Dannenmaier W. Clauss 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1993,163(2):153-159
The dorsal skin of the leech Hirudo medicinalis was used for electrophysiological measurements performed in Ussing chambers. The leech skin is a tight epithelium (transepithelial resistance = 10.5±0.5 k· cm-2) with an initial short-circuit current of 29.0±2.9 A·cm-2. Removal of Na+ from the apical bath medium reduced short-circuit current about 55%. Ouabain (50mol·l-1) added to the basolateral solution, depressed the short-circuit current completely. The Na+ current saturated at a concentration of 90 mmol Na+·l-1 in the apical solution (K
M=11.2±1.8 mmol·l-1). Amiloride (100 mol·l-1) on the apical side inhibited ca. 40% of the Na+ current and indicated the presence of Na+ channels. The dependence of Na+ current on the amiloride concentration followed Michaclis-Menten kinetics (K
i=2.9±0.4 mol·l-1). The amiloride analogue benzamil had a higher affinity to the Na+ channel (K
i=0.7±0.2 mol·l-1). Thus, Na+ channels in leech integument are less sensitive to amiloride than channels known from vertebrate epithelia. With 20 mmol Na+·l-1 in the mucosal solution the tissue showed an optimum amiloride-inhibitable current, and the amiloride-sensitive current under this condition was 86.8±2.3% of total short-circuit current. Higher Na+ concentrations lead to a decrease in amiloride-blockade short-circuit current. Sitmulation of the tissue with cyclic adenosine monophosphate (100 mol·l-1) and isobutylmethylxanthine (1 mmol·l-1) nearly doubled short-circuit current and increased amiloride-sensitive Na+ currents by 50%. By current fluctuation analysis we estimated single Na+ channel current (2.7±0.9 pA) and Na+ channel density (3.6±0.6 channels·m-2) under control conditions. After cyclic adenosine monophosphate stimulation Na+ channel density increased to 5.4±1.1 channels·m-2, whereas single Na+ channel current showed no significant change (1.9±0.2 pA). These data present a detailed investigation of an invertebrate epithelial Na+ channel, and show the similarities and differences to vertebrate Na+ channels. Whereas the channel properties are different from the classical vertebrate Na+ channel, the regulation by cyclic adenosine monophosphate seems similar. Stimulation of Na+ uptake by cyclic adenosine monophosphate is mediated by an increasing number of Na+ channels.Abbreviations
slope of the background noise component
- ADH
antidiuretic hormone
- cAMP
cyclic adenosine monophosphate
-
f
frequency
-
f
c
coner frequency of the Lorentzian noise component
- Hepes
N-hydroxyethylpiperazine-N-ethanesulphonic acid
- BMX
isobutyl-methylxanthine
-
i
Na
single Na+ channel current
-
I
Na
max, maximal inhibitable Na+ current
-
I
SC
short circuit current
-
K
i
half maximal blocker concentration
-
K
M
Michaelis constandard error of the mean
-
S
(f)
power density of the Lorentzian noise component
-
S
0
plateau value of the Lorentzian noise component
- TMA
tetramethylammonium
- Trizma
TRIS-hydroxymethyl-amino-methane
-
V
max
maximal reaction velocity
-
V
T
transepithelial potential
-
K
half maximal blocker concentration 相似文献
1000.
M. V. Wright N. Elwess J. van Houten 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1993,163(4):288-296
Intracellular Ca2+ levels in Paramecium must be tightly controlled, yet little is understood about the mechanisms of control. We describe here indirect evidence that a phosphoenzyme intermediate is the calmodulin-regulated plasma membrane Ca2+ pump and that a Ca2+-ATPase activity in pellicles (the complex of cell body surface membranes) is the enzyme correlate of the plasma membrane pump protein. A change in Ca2+ pump activity has been implicated in the chemoresponse of paramecia to some attractant stimuli. Indirect support for this is demonstrated using mutants with different modifications of calmodulin to correlate defects in chemoresponse with altered Ca2+ homeostasis and pump activity.Abbreviations EGTA
ethyleneglycol tetra-acetate
- ER
endoplasmic reticulum
- IBMX
isobutyl methylxanthine
-
I
che
index of chemokinesis
- Mops
3-[N-morpholino] propanesulfonic acid
- PEI
phosphoenzyme intermediate
- STEN
sucrose, TRIS, EDTA, sodium chloride
- TCA
trichloroacetic acid
- TRIS
tris[hydroxymethyl] aminomethane 相似文献