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991.
Abstract: Changes in brain protein synthesis activity, and in brain levels of glucose, glycogen, and several high-energy phosphate metabolites, were evaluated under conditions of amphetamine-induced hyperthermia in mice. Protein synthesis showed a striking dependence on rectal temperature ( T R), falling abruptly at T R above 40°C. A similar result was obtained following direct heating of the animals. Protein synthesis activity in liver showed the same temperature dependence observed for brain. Increased synthesis of a protein with characteristics of the major mammalian stress protein, hsp 70, was demonstrated in both brain and liver following amphetamine administration. Brain protein synthesis showed significant recovery within 2 h after amphetamine administration whereas that of liver remained below 30% of control activity, suggesting significant temporal and quantitative differences in the response of individual tissues to elevated temperatures. Brain glycogen levels after amphetamine administration were significantly lower under conditions of ambient temperature which resulted in more severe drug-induced hyperthermia but did not correlate as strikingly as protein synthesis with the temperatures of individual animals. Brain glycogen also fell in animals whose temperatures were increased by brief exposure at high ambient temperature. Brain glucose levels did not consistently change with hyperthermia. Slight decreases in high-energy phosphates with increasing T R were likely the result of fixation artifact. These results demonstrate the fundamental role of hyperthermia in the reduction of protein synthesis in brain and other tissues by amphetamine, and suggest that temperature also constitutes a significant source of variability in the effects of this drug on brain energy metabolism, in particular glycogenolysis.  相似文献   
992.
    
Zusammenfassung Unsere Kenntnis der saisonalen Wanderungen von Lebewesen ist nicht ausreichend. Dies wird vor allem bei Schutzmaßnahmen regelmäßig deutlich; die bisher angewandten Methoden der Markierung sind nicht optimal und kaum zu verbessern. Insbesondere für den Schutz wandernder Tiere besteht ein verstärkter Bedarf an qualitativ und quantitativ neuwertigen Informationen über den Zugablauf, die rasch zur Verfügung stehen sollten.In letzter Zeit wurde eine Reihe verschiedener neuer Methoden zur Erforschung von Tierwanderungen erprobt, wobei die Satelliten-Telemetrie (ST) am aussichtsreichsten erscheint. Wir geben eine Literaturübersicht über die bisherigen Untersuchungen mit ST, machen einen Forschungsvorschlag im Auftrag des Naturschutz-Ressorts der Bundesregierung und diskutieren die ST im Hinblick auf Schutzvorhaben. Aus jüngster Zeit liegen erste publizierte Berichte über satellitentelemetrische Untersuchungen der Wanderungen des Karibus, des Eisbären, Schwarzbären, des Kamels, von einigen Walarten, der Kegelrobbe, der Westindischen Rundschwanzsirene, des Dugongs, der unechten Karett- und der Lederschildkröte, des Riesenhais sowie von vier grßen Vogelarten vor; einige weitere Experimente sind im Gange. Pionieruntersuchungen der Wanderungen des Weißkopfseeadlers, von Schwänen und des Riesensturmvogels in Amerika haben die Möglichkeit der Anwendung der ST im Bereich des Vogelzuges belegt; Untersuchungen der vollständigen Jahres-Wanderstrecken von Vogelarten fehlen aber noch gänzlich. Satelliten-Telemetrie ist insbesondere in der Lage, den Verlauf von Wanderungen nahezu lückenlos zu beschreiben, so daß sich zusammen mit Zusatzinformationen räumlich-zeitliche Ökodiagramme von wandernden Individuen aufstellen lassen. Neben der Wanderroute lassen sich Rastplätze, Biotopwahl, Verweildauer, Zugstrategien u. a. m. genau ermitteln. Derartig genaue Zuganalysen sind für internationale Schutzmaßnahmen wie z. B. die Bonner Konvention von grundlegender Bedeutung.Es wird ein Plan vorgestellt, von der Bundesrepublik Deutschland aus mittels eines Experimentalsatelliten (u. U. TUB SAT 1 der Technischen Universität Berlin) eine Satelliten-Telemetrie-Untersuchung am Weißstorch durchzuführen, und zwar an mit Sendern ausgerüsteten Vögeln sowohl auf der Westroute über Spanien als auch auf der Ostroute über den östlichen Mittelmeerraum. Das Projekt wird im einzelnen beschrieben. Das wichtigste zu erwartende Ergebnis ist ein Ökodiagramm des Storchenzuges von Europa bis Südafrika und zurück, aus dem u. a. konkrete Schutzmaßnahmen abgeleitet werden könnten. Daneben sind neue Erkenntnisse im Bereich der Grundlagenforschung, z. B. über die Orientierung, über Methoden der Öffentlichkeitsarbeit u. a. zu erwarten. Das Storchvorhaben würde zum ersten Mal die gesamte Jahres-Wanderstrecke einer ziehenden Vogelart erfassen.
Satellite telemetry in the study of animal migration: a review
Summary Our knowledge of annual migration in animals is insufficient, and the hitherto applied methods of individual marking are neither optimal nor can they essentially be improved. This problem becomes especially clear when dealing with conservation projects. With regard to the conservation of migrating animals, there is a great need for more qualitative and quantitative information about their migration systems, and this information should soon be available. In the last decades, a number of new methods for the investigation of animal migration have been tested. Among these, satellite radio tracking (SRT) appears to be most promising. Here we present a literature review of that new method, a research proposal by order of the nature conservancy department of the Government of the Federal Republic of Germany (FRG), and a discussion on the relevance of satelite radio tracking to conservation projects.Recently, reports of investigations using SRT have been published forRangifer terandus, Ursus maritimus, Ursus americanus, Camelus dromedarius, Physeter catodon and related species,Halichoerus gryphus, Trichechus manatus, Dugong dugon, Caretta caretta, Dermochelys coriacea, Cetorrhinus maximus as well as for four large bird species (see 5). Pioneer studies withHaliaeetus leucocephalus, Cygnus buccinator, C. columbianus andMacronectes giganteus have shown that SRT is feasible for the study of bird migration. Coverage of the overall migratory movements of a migratory species within a year, however, has, to date, not been obtained.SRT makes it possible to describe migratory routes almost completely, and so, in combination with additional information, spatial-temporal eco-diagrams of migrating individuals can be obtained. In addition to the migratory routes, resting places, habitat preferences, duration of stop-over periods, migration strategies, etc., can be established. All these data are of basic importance for the realization of conservation projects such as the Bonn Convention.The following research proposal is presented in some detail: White Storks from the FRG, equipped with transmitters, should be tracked with SRT along the western route via Spain as well as along the eastern route via the eastern Mediterranean; this should be done using an experimental satellite (possibly TUB SAT 1 of the Technical University of Berlin). The most important result would be to obtain an eco-diagram of Stork migration from Europe to South Africa and back; this would be helpful in the organization of stork protection measures. In addition, results concerning the mechanisms of orientation, methods of public relations, etc. are to be expected. In this White Stork project, the entire annual migration of a bird species could be fully understood for the first time.
  相似文献   
993.
Summary In the hamster, the weight of the adrenal glands increases during the course of gestation, with the highest value at day 5. In comparison to non-pregnant control animals, there were no changes in the volume of the zona glomerulosa (ZG) and zona fasciculata (ZF), while the volume of the zona reticularis (ZR) increased notably. The average volume of ZG-cells rose at day 5 of pregnancy and thereafter gradually decreased to that of control hamsters. A marked drop in the volume of ZF-cells was seen at days 5 and 10 of pregnancy, whereas at day 15 the cells were larger than in controls. At day 5 of pregnancy, a conspicuous increase in the cell volume was found in ZR, followed by lower values at day 10 and again higher than in control hamsters at day 15. The total number of parenchymal cells in hamster adrenal cortex increased at day 10 of gestation, then underwent a marked decrease, reaching the control value at the final day of pregnancy; this drop was mainly due to a reduction in the number of ZF-cells. The changes in the cell volume were paralleled by rather proportional changes in the volume of the mitochondrial compartment and in the quantity of smooth endoplasmic reticulum. The volume of the lipid-droplet compartment significantly rose in the course of gestation in both ZF- and ZR-cells. The cortisol output by adrenal homogenates gradually decreased during pregnancy.Study performed in partial fulfillment of the Ph.D. Thesis of Magdalena Nowak  相似文献   
994.
effective pharmacological procedures are described which markedly increase activity of serotonin N-acetyltransferase (NAT), the key regulatory enzyme in melatonin biosynthesis, during the daytime (in light) and counteract suppressive effects of light on NAI activity at night in the hen retina and pineal gland. Of the tested compounds, and their combinations, the most effective were: “aminophylline + spiroperidol + alpha-methyl-p-tyrosine” for the retina, and “aminophylline + yohimbine (+ alpha-methyl-p-tyrosine)” for the pineal gland. The results give strong support to the concept that the dopaminergic (C2-receptor) and noradrenergic (alpha2-adrenergic receptor) mechanisms control NAT activity, and melatonin synthesis, in the hen retina and pineal gland, respectively.  相似文献   
995.
The study was designed to evaluate some parameters of carbohydrate metabolism in the rat as influenced by 4-APP, an adenine analogue. Adult female rats were injected with 1 mg 4-APP/100 g body weight/day for 3 days. 4-APP evoked a marked enlargement of the liver with lipid droplets accumulation in hepatocytes. This was accompanied by a marked lowering of the liver glycogen content. Within 3 days 4-APP did not change serum glucose, insulin and free fatty acid concentration. Serum glycogenolytic activity studied in an in vitro system showed 7 times as high glucose releasing ability in 4-APP treated rats as that of the serum of control animals. 4-APP resulted also in a marked enlargement of the adrenal medulla and lowered adrenaline and noradrenaline concentrations in the gland. The possibility of an activation of glycogenolysis in the liver of 4-APP treated rats has been discussed.  相似文献   
996.
The modification of avian phosphoenolpyruvate carboxykinase by a variety of sulfhydryl reagents leads to inhibition. The inhibition is related to the loss of 1 highly reactive cysteine residue of the 13 cysteines present in the enzyme. Inhibition by reagents which yield a mixed disulfide was rapidly reversed by thiols. Reagents specific for vicinal sulfhydryl configurations were not potent inhibitors. The cysteine-modified enzyme continues to bind Mn2+ with the same stoichiometry and dissociation constant as the native enzyme. All of the substrates also bind to thiol-modified inactive enzyme. The modification of the reactive cysteine with the spin-labeled iodoacetate derivative leads to inactive enzyme with spin label stoichiometrically incorporated. The EPR spectrum showed an immobilized spin label on the enzyme. EPR studies of the perturbation of the phosphoenolpyruvate carboxykinase-bound spin label by bound Mn2+ showed a dipolar interaction between the two spins, estimated to be 10 A apart. The perturbation of the 1/T1 and 1/T2 values of the 31P resonances of ITP by spin-labeled enzyme indicates that this portion of the nucleotide binds 8-10 A from the spin label. These results indicate that the reactive cysteine is close to but not at the active site of the enzyme. The thiol group must be free and in its reduced form for the enzyme to be active. Perhaps modification of this group prevents conformational change(s) upon ligand binding necessary for the catalytic process.  相似文献   
997.
The time course of the reduction in brain protein synthesis following transient bilateral ischemia in the gerbil was characterized and compared with changes in a number of metabolites related to brain energy metabolism. The recovery of brain protein synthesis was similar following ischemic periods of 5, 10, or 20 min; in vitro incorporation activity of brain supernatants was reduced to approximately 10% of control at 10 or 30 min recirculation, showed slight recovery at 60 min, and returned to 60% of control activity by 4 h. Protein synthesis activity was indistinguishable from control at 24 h. One minute of ischemia produced no detectable effect on protein synthesis measured after 30 min reperfusion; longer periods of ischemia resulted in progressive inhibition, with 5 min producing the maximal effect. Pentobarbital (50 mg/kg) increased by 1-2 min the threshold ischemic duration required to produce a given effect. Whereas most metabolites recovered quickly following 5 min ischemia, glycogen showed a delayed recovery comparable to that seen for protein synthesis. These results are discussed in relation to possible mechanisms for the coordinate regulation of brain energy metabolism and protein synthesis. An improved method for the fluorimetric measurement of guanine nucleotides is described.  相似文献   
998.
Described is a special purpose cone-plate viscometer that is capable of acceleration or deceleration through a step change in speed in less than 0.7s. The speed of the rotating cone is controlled by a microcomputer which can be programmed to generate speed vs time ramp functions of variable slope. Prior calibration of motor power required to shear Newtonian fluids of known viscosity at various speeds provides the basis for determination of apparent suspension viscosity and enables the viscometer automatically to compensate for changing sample viscosity during shear. The viscometer was used to carry out a series of preliminary studies in which platelet-rich plasma (PRP) was subjected to continuous and pulsatile shear stress at 37 degrees C. Shear-induced platelet aggregation (SIPAG) was significantly greater in response to pulsatile versus continuous shearing except at the lowest applied stress (10 dyn/cm2). Increases ranged from about 40 percent at a stress amplitude of 25 dyn/cm2 to nearly 55 percent at dyn/cm2. This increasing trend with stress amplitude might be interpreted as a positive correlation between SIPAG and the loading rate. Dense granule release, as indicated by serotonin release, was dependent on both stress amplitude and number of pulses even at the higher stress where SIPAG was independent of pulse number.  相似文献   
999.
Comparison of two types of Ca2+-regulated thin filament, reconstructed in ghost fibers by incorporating either caldesmon-gizzard tropomyosin-calmodulin or skeletal muscle troponin-tropomyosin complex, was performed by polarized microphotometry. The changes in actin structure under the influence of these regulatory complexes, as well as those upon the binding of the myosin heads, were followed by measurements of F-actin intrinsic tryptophan fluorescence and the fluorescence of phalloidin-rhodamine complex attached to F-actin. The results show that in the presence of smooth muscle tropomyosin and calmodulin, caldesmon causes Ca2+-dependent alterations of actin conformation and flexibility similar to those induced by skeletal muscle troponin-tropomyosin complex. In both cases, transferring of the fiber from '-Ca2+' to '+Ca2+' solution increases the number of turned-on actin monomers. However, whereas troponin in the absence of Ca2+ potentiates the effect of skeletal muscle tropomyosin, caldesmon-calmodulin complex inhibits the effect of smooth muscle tropomyosin. This difference seems to be due to the qualitatively different alterations in the structure and flexibility of F-actin in ghost fibers evoked by smooth and skeletal muscle tropomyosins. Troponin can bind to F-actin-smooth muscle tropomyosin-caldesmon complex and, in the presence of Ca2+, release the restraint by caldesmon for S-1-induced alterations of conformation, and reduce that for flexibility of actin in ghost fibers. This effect seems to be related to the abolishment by troponin of the potentiating effect of tropomyosin on caldesmon-induced inhibition of actomyosin ATPase activity.  相似文献   
1000.
The physico‐chemical background of alkaloid allocation within plants is outlined and discussed exemplarily for pyrrolizidine alkaloids (PAs) and nicotine. The trigger for this discourse is the finding that, for example, PAs, which are taken up from the soil, are translocated in the xylem, whereas – when genuinely present in plants – they are allocated as N‐oxides via phloem. Special emphasis is put on the impact of different pH values in certain compartments, as this entails significant changes in the relative lipophilic character of alkaloids: tertiary alkaloids diffuse readily through biomembranes, while the corresponding protonated alkaloids are retained in acidic compartments, i.e. vacuoles or xylem. Therefore, this phenomenon, well known as the ‘ion trap mechanism’, is also relevant for long‐distance transport of alkaloids. Any efficient allocation of typical tertiary alkaloids within the phloem can thus be excluded. In contrast, due to their strongly increased hydrophilic properties, alkaloid‐N‐oxides or quarternary alkaloids cannot diffuse through biomembranes and, consequently, would be retained in the acidic xylem during translocation. The major aim of this paper is to sharpen the mind for the chemical peculiarities of alkaloids and to consider them adequately in forthcoming investigations on allocation of alkaloids.  相似文献   
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