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41.
Bente Christiansen Jens Pete Lomholt Kjell Johansen 《Environmental Biology of Fishes》1982,7(3):291-296
Synopsis Oxygen uptake (Vo
2) was measured in carp of approximately 40 cm length swimming at controlled variable oxygen tensions (Po
2). At Po
2> 120 mm Hg Vo
2 increased with an increase in swimming speed from 5.6 to 11.3 cm · sec–1. Extrapolation of Vo
2 to zero activity at Po
2 = 140 mm Hg revealed a standard O2 uptake of 36.7 ml O2 · kg–1 · h–1 at 20° C. At the lowest swimming speed (5.6 cm · s–1) the oxygen uptake increased when the water Po
2 was reduced. A near doubling in Vo
2 was seen at Po
2 = 70 mm Hg compared to 140 mm Hg. At higher swimming speeds in hypoxic water Vo
2 decreased relative to the values at low swimming speeds. As a result the slope of the lines expressing log Vo
2 as a function of swimming speed decreased from positive to negative values with decreasing Po
2 of the water. pH of blood from the caudal vein drawn before and at termination of swimming at Po
2 = 70 mm Hg and 100 mm Hg did not show any decrease in relation to rest values at Po
2 = 140 mm Hg. Blood lactate concentration did not increase during swimming at these tensions. 相似文献
42.
Synopsis In serial cross-sections of human skeletal muscles stained for either NADH-tetrazolium reductase (NADH-TR) or -glycerophosphate dehydrogenase (-GPD), a linear relation was found between the total content of enzyme in a cell (expressed as the thickness of the section) and the absorbance of the formazan reaction product formed. Little variation (<4.8%) was found in the concentration of formazan (absorbance per unit thickness) when the same cell was measured in serial cross-sections of various thicknesses (2–10 m) along a longitudinal distance of at least 200 m along the cell. The reduction in enzyme activity was found to be negligible after aqueous preincubation. A maximum of 10–12% of the formazan produced in the NADH-TR reaction might be the result of nothing dehydrogenase activity, whereas this unspecific reaction might account for up to 20% of the formazan deposited in the -GPD reactions after 30 min incubation. The diffusion of Nitro BT into the tissue during the incubation period was found to be unhindered. The rates of formazan production decreased with increasing incubation time, especially in the -GPD reaction in both fibre types. The ratio of the mean absorbance of the formazan in type I fibres to that in type II fibres (in the same section) was 1.41 (coefficient of variation, 2.5%) in the NADH-TR reaction and 0.68 (coefficient of variation, 3.8%) in the -GPD reaction. These values were not affected either by variations in the incubation time (5–40 min) or by the thickness of the section (2–8 m). The concentrations of NADH-TR and -GPD seem to be constant along the length of the muscle fibre. The histochemical reactions reported, together with measurements of the thickness of the sections, seem suitable for the microphotometric quantification of the two enzymes in single fibres of human skeletal muscles. 相似文献
43.
Jens Kvist Nielsen 《Entomologia Experimentalis et Applicata》1978,24(1):41-54
Feeding responses of four Chrysomelidae to six less acceptable plants and to compounds from them were investigated by means of leaf disc tests. Significant differences were found between responses of different species, and plants containing potent feeding inhibitors were always rejected. Cucurbitacins are potent feeding inhibitors to Phyllotreta nemorum, and this species does not eat Iberis species containing these compounds. Cardenolides are potent feeding inhibitors to P. undulata, P. tetrastigma and Phaedon cochleariae, and these three species do not eat the cardenolide containing Cheiranthus and Erysimum.Six different glucosinolates all proved to be stimulatory when applied to pea leaf discs. Although the glucosinolates differed somewhat in their ability to stimulate feeding, no correlation is found between content of glucosinolates and acceptability of the investigated plants. Application of sinigrin to Iberis and Cheiranthus did not improve their acceptability. The presence of glucosinolates is necessary for feeding to occur, but it is less important which glucosinolates are present.Cardenolides and cucurbitacins are suggested to be a second generation of protective compounds in Cruciferae, glucosinolates being the first.
The Danish Natural Science Research Council supported the research. 相似文献
Zusammenfassung Der Einfluss einiger sekundärer Pflanzenstoffe aus Cruciferen auf die Futteraufnahme von vier Chrysomeliden, die auf dieser Pflanzenfamilie vorkommen, wurde mittels Blattscheiben-Tests untersucht. Cucurbitacine sind starke Frasshemmstoffe für Phyllotreta nemorum, weniger starke Hemmstoffe für P. undulata und schwache Hemmstoffe für P. tetrastigma und Phaedon cochleariae. Iberis-Arten, die Cucurbitacine enthalten, werden von P. nemorum und P. undulata abgelehnt, von den beiden anderen Arten aber akzeptiert. Cardenolid-Glykoside vom Strophanthidin-Typ sind starke Frasshemmstoffe für P. undulata, P. tetrastigma und Phaedon cochleariae. Diese Arten lehnen Cheiranthus-und Erysimum-Arten, die solche Stoffe enthalten, ab. Die Futteraufnahme von P. nemorum wird von diesen Stoffen nicht beeinflusst; P. nemorum akzeptiert Cheiranthus- und Erysimum-Arten.Futteraufnahme fand bei Abwesenheit von Senfölglukosiden nicht statt. Sechs verschiedene Senfölglukoside waren alle imstande, das Aufnehmen von Erbsen-Blattscheiben zu stimulieren. Gewisse Unterschiede in der stimulierenden Wirkung der einzelnen Glukoside wurden gefunden. Das Vorkommen bestimmter Glukoside und die Akzeptabilität der Pflanzen zeigten aber keine Korrelation. Anwesenheit oder Abwesenheit von Frasshemmstoffen beeinflusst die Akzeptabilität der Pflanzenarten mehr als die Anwesenheit bestimmter Senfölglukoside.Wenn Senfölglukoside als eine erste Generation von Abwehrstoffen in Cruciferen aufgefasst werden, können Cucurbitacine in Iberis und Cardenolid-Glykoside in Cheiranthus und Erysimum als eine zweite betrachtet werden.
The Danish Natural Science Research Council supported the research. 相似文献
44.
Rafiquzzaman Muhammad Svenkerud Rolf Strande Anders Hange Jens G. 《Acta veterinaria Scandinavica》1976,17(2):196-209
Four cases of a generalized form of glycogenosis occurring in German Shepherd dogs, all females, are described. Symptoms could be noticed as early as the age of two months and progressed slowly for months. They appeared as dizziness, muscular weakness, and in two of the cases as poor nutritional state. The abdomen became gradually distended. The main lesion seen at postmortem was a greatly increased liver size with some moderate liver fibrosis. Heavy deposits of a granular substance behaving as glycogen in histochemical tests and at electron microscopy were found in the hepatic cells, muscle fibres of the heart, skeletal and smooth muscles, and in nerve and glial cells of the central nervous system. The substance was lying freely dispersed in the cell cytoplasm without any indication of lysosomal storage. The disease of dogs does not seem to be fully comparable with any of the types observed in man, but is probably much related to Type III or Cori's Disease. Structure analysis of the deposits and enzyme investigations have been done and are published (Čeh et al. 1976). 相似文献
45.
46.
Evidence for Geographic Isolation and Signs of Endemism within a Protistan Morphospecies 总被引:4,自引:0,他引:4 下载免费PDF全文
Jens Boenigk Karin Pfandl Tobias Garstecki Hauke Harms Gianfranco Novarino Antonis Chatzinotas 《Applied microbiology》2006,72(8):5159-5164
The possible existence of endemism among microorganisms resulting from and preserved by geographic isolation is one of the most controversial topics in microbial ecology. We isolated 31 strains of “Spumella-like” flagellates from remote sampling sites from all continents, including Antarctica. These and another 23 isolates from a former study were characterized morphologically and by small-subunit rRNA gene sequence analysis and tested for the maximum temperature tolerance. Only a minority of the Spumella morpho- and phylotypes from the geographically isolated Antarctic continent follow the worldwide trend of a linear correlation between ambient (air) temperature during strain isolation and heat tolerance of the isolates. A high percentage of the Antarctic isolates, but none of the isolates from locations on all other continents, were obligate psychrophilic, although some of the latter were isolated at low ambient temperatures. The drastic deviation of Antarctic representatives of Spumella from the global trend of temperature adaptation of this morphospecies provides strong evidence for geographic transport restriction of a microorganism; i.e., Antarctic protistan communities are less influenced by transport of protists to and from the Antarctic continent than by local adaptation, a subtle form of endemism. 相似文献
47.
Søren Ugilt Larsen Uffe Jørgensen Jens Bonderup Kjeldsen Poul Erik Lærke 《Bioenergy Research》2014,7(2):620-635
Long-term yield studies in perennial crops like miscanthus are important to determine mean annual energy yield and the farmer’s economy. In two Danish field trials, annual yield of two miscanthus genotypes was followed over a 20-year period. The trials were established in 1993 on loamy sand in Foulum and on coarse sand in Jyndevad. Effects of genotype, row distance and fertilization were investigated. In both trials, yield development over time was characterized by an increase during the first years, optimum yields after 7–8 years and a decrease to a lower level which remained relatively constant from year 11 to 20. Spring harvest reduced the yield by 34–42 % compared to autumn harvest. In Foulum annual fertilization with 75 kg ha?1 N increased the yield of the genotype Goliath (Miscanthus sinensis) by 26 %. Additional N fertilization only increased the yield of Goliath little, and the genotype Giganteus (Miscanthus?×?giganteus) did not respond to fertilization at all. The highest mean yield in Foulum for the period 1997–2012 was obtained with the shortest row distance (~18,000 rather than ~12,000 plants ha?1) and harvested in late autumn, namely 13.1 and 12.0 Mg ha?1 DM annually for Giganteus and Goliath, respectively. In Jyndevad, where only Goliath was studied, the highest yield during 1995–2001 was obtained by short row distance, autumn harvest and annual fertilization with 75 kg ha?1 N, with yield increasing up to 116 % in response to fertilization. A mean yield of 14.4 Mg ha?1 DM was achieved over the period 1995–2012. 相似文献
48.
Benjamin F Miller Mette Hansen Jens L Olesen Peter Schwarz John A Babraj Kenneth Smith Michael J Rennie Michael Kjaer 《Journal of applied physiology》2007,102(2):541-546
In general, there is a higher incidence of musculoskeletal injuries during physical activity in women than in men. We hypothesized that in women rates of tendon collagen synthesis would be lower than in men at rest and after exercise, especially in the later luteal phase when estrogen and progesterone concentrations are higher than the early follicular phase. We studied tendon collagen fractional synthesis rate (FSR) in 15 young, healthy female subjects in either the early follicular (n = 8) or the late luteal phase (n = 7) 72 h after an acute bout of one-legged exercise (60 min kicking at 67% workload maximum) (72 h) and compared the results with those previously obtained for men. Samples were taken from the patellar tendon in both the exercised and rested legs to determine collagen FSR by the incorporation of [15N]proline into tendon collagen hydroxyproline. There was no effect of menstrual phase on tendon collagen synthesis either at rest or after exercise. However, there was a significant difference between women and men at rest (women = 0.025 +/- 0.002%/h, men = 0.045 +/- 0.008%/h; P < 0.05) and 72 h after exercise (women = 0.027 +/- 0.005%/h; men = 0.058 +/- 0.008%/h). Furthermore, rest and 72-h tendon collagen synthesis were not different in women, whereas in men tendon collagen synthesis remained significantly elevated 72 h after exercise. It is concluded that both in the resting state and after exercise, tendon collagen FSR is lower in women than in men, which may contribute to a lower rate of tissue repair after exercise. 相似文献
49.
50.
Distribution and diversity of palms in a tropical biodiversity hotspot (Thailand) assessed by species distribution modeling 下载免费PDF全文
Jantrararuk Tovaranonte Anne Blach‐Overgaard Ratchada Pongsattayapipat Jens‐Christian Svenning Anders S. Barfod 《Nordic Journal of Botany》2015,33(2):214-224
Species distribution modeling has been widely used to address questions related to ecology, biogeography and species conservation on global and regional scales. Here, we study palms (Arecaceae) in a tropical biodiversity hotspot (Thailand) using species distribution modeling to assess range‐limiting factors and estimate distribution and diversity patterns based on a comprehensive compilation of occurrence records. We focused on palms as a model group due to their key‐stone importance for ecosystem functioning and socio‐economics. Different combinations of climatic, non‐climatic environmental and spatial predictors were used. The most accurate models as indicated by the ‘area under the receiver operating characteristic curve’ (AUC) statistic were those that combined all predictors. The four strongest single predictors of palm species distributions were, in decreasing order of importance, 1) latitude, 2) precipitation of driest quarter, 3) annual precipitation, and 4) minimum temperature of the coldest month, suggesting rainfall patterns and latitudinal spatial constraints as the main range determinants. Overlaying the predicted distributions revealed that potential palm hotspots are situated in the provinces of Satun and Yala in southern Thailand where vast areas remain relatively open to the discovery of new palm records and perhaps even new species. 相似文献