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901.
902.
The influence of 0.5 mM gamma-hexachlorocyclohexane (gamma-HCH, lindane) on glucose transport has been investigated using the analog 3-O-methyl-D-(U-14C)glucose. The glucose uptake was lineal for at least 10 sec. Preincubation of dissociated brain cortex cells with lindane decreased the transport of glucose with respect to the controls. The treatment of brain cortex cells with other organochlorine compounds indicated that the alpha-, delta-HCH isomers and dieldrin reproduced the same inhibitory pattern, while beta-HCH and endrin were inactive. The total radioactivity incorporated into CO2 from (U-14C) glucose in the cerebral cortex is also inhibited by lindane in a time dependent manner. 相似文献
903.
Hemandez Rafael; Esteban Jose A.; Garcia Margarita; Moran Federico 《Bioinformatics (Oxford, England)》1991,7(2):169-174
In this paper we describe PASHEMOS, a user-friendly programwritten in Pascal to solve the MeinhardtKlingler modelnumerically. This model studies the shell pattern pigmentationof molluscs. Moreover, PASHEMOS enables theoretical analysisto be performed on the different steady states. The programtakes into account the four differential equation systems establishedin the model. It numerically solves these systems. This programis developed in such a way that both the equation system typeand the parameter values can be chosen. The pattern is displayedin each case, and other output possibilities are available (i.e.three-dimensional concentration plotting, phase plane, phasespace, stability analysis). The implementation of the programfor the case of a three-variable system is shown as an exampleof PASHEMOS handling. Program applications for other modelsare also discussed.
Received on March 22, 1990; accepted on August 28, 1990 相似文献
904.
Valeria Maida Federico Bennardini Francesco Bonomi Maria Luisa Ganadu Stefania Iametti Giovanni Maria Mura 《The protein journal》2000,19(4):311-318
Conformational modifications and changes in the aggregation state of human αB-crystallin were investigated at different concentrations of SDS, KBr, urea, and NH4SCN and at different temperatures. Intrinsic fluorescence measurements indicated complete and reversible unfolding of the protein at 2 M NH4SCN, whereas the concentration of urea required for complete and irreversible unfolding was 6 M. Gel permeation chromatography indicated almost complete dissociation of the micelle-like aggregate of αB-crystallin in 2 M NH4SCN, but only partial dissociation into large-sized aggregates in 6 M urea. Thiocyanate-treated αB-crystallin recovered its chaperone-like activity upon dilution of the dissociating agent, whereas the urea-treated protein did not. 相似文献
905.
Federico M. Winkler Beatriz F. Estévez 《Journal of experimental marine biology and ecology》2003,292(1):93-102
Argopecten purpuratus Lamarck (1819) is a functional hermaphrodite that releases successively male and female gametes during their spawning process. Because the short period between the release of both kind of gametes, the chance of self-fertilization exists, even in natural conditions. The self-fertilization rate was quantified in 10 scallops as the proportion of spontaneous (nonartificially fertilized) cleaving eggs. The existence of inbreeding depression was tested comparing families produced by self- and cross-fertilization. An average of 9.9% of spontaneous self-fertilization was detected. No differences in survival or growth in either larvae or juvenile were found between families produced by self-fertilization and pair mating. 相似文献
906.
907.
Acetylcholine and Dopamine Promote the Production of Platelet Activating Factor in Immature Cells of Chick Embryonic Retina 总被引:2,自引:1,他引:1
Federico Bussolino Gianpiero Pescarmona Giovanni Camussi Fulvia Gremo† 《Journal of neurochemistry》1988,51(6):1755-1759
We have previously shown that platelet-activating factor (PAF), a naturally occurring lipid mediator of cell-to-cell communication, was produced by 3-day-old chick retina stimulated with acetylcholine (ACh) and dopamine (DA), but not with other neurotransmitters. ACh and DA stimulated PAF synthesis via a dithiothreitol (DTT)-insensitive cholinephosphotransferase, without affecting the acetyltransferase pathway, which was stimulated only by the calcium ionophore A23187. Therefore, we attempted to study the effects of neurotransmitters on PAF production and on the activities of the DTT-insensitive cholinephosphotransferase and acetyltransferase in the developing chick embryo retina up to hatching. Our results show that PAF was produced already at 8 days of development, when retinal cells are still rather immature and ganglion and Mueller cells are the only differentiated cells. The stimulation of PAF production occurred with ACh and not with other neurotransmitters. In older stages, DA also stimulated PAF production, as already described in the chick after hatching. DTT-insensitive cholinephosphotransferase and acetyltransferase activities were present in 8-day-old embryos, the earliest stage analyzed. Both enzymatic activities increased with age; DTT-insensitive cholinephosphotransferase increased rapidly from day 12 up to day 18, whereas acetyltransferase activity increased linearly up to the time of hatching. To promote PAF production, ACh and DA activate DTT-insensitive cholinephosphotransferase, but not acetyltransferase.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
908.
Giacomo Grassi Francesco Ripullone Marco Borghetti Sabrina Raddi Federico Magnani 《Trees - Structure and Function》2009,23(6):1149-1161
It is still unknown whether the midday depression of photosynthesis under severe water stress, frequently observed in plants
growing in a Mediterranean-type climate, is primarily a consequence of diffusional or non-diffusional limitations. We carried
out combined measurements of gas exchanges and chlorophyll fluorescence in field-grown Arbutus unedo L. trees during late spring and mid summer, and a quantitative limitation analysis was performed to distinguish between the
different limitations to photosynthesis, i.e., diffusional [D
L = stomatal (S
L) + mesophyll (MCL)] and non-diffusional (carboxylation capacity and electron transport, B
L) limitations. Light-saturated assimilation at ambient CO2 (A
max), stomatal conductance to water vapour (g
sw) and maximum carboxylation rate (V
cmax
C
i) showed a marked midday depression during both periods. The total limitations tended to increase during the day and were
remarkably similar in June and July (50 and 48%, respectively); on a daily basis, D
L was similar to B
L (about 23%) in June; whereas, in July the former was predominant (38 and 4%, respectively). We concluded that the midday
depression in photosynthesis was largely caused by diffusional limitations, with non-diffusional limitations playing a smaller
role. Although stomatal closure was the main diffusional limitation, the decline in mesophyll conductance was not negligible
during the hottest and driest period. 相似文献
909.
In this study, we investigated the metabolic responses of potato tissue induced by pulsed electric field (PEF). Potato tissue
was subjected to field strengths ranging from 30 to 500 V/cm, with a single rectangular pulse of 10 μs, 100 μs, or 1 ms. Metabolic
responses were monitored using isothermal calorimetry, changes on electrical resistance during the delivery of the pulse,
as well as impedance measurements. Our results show that the metabolic response involves oxygen consuming pathways as well
as other unidentified events that are shown to be insensitive to metabolic inhibitors such as KCN and sodium azide. The metabolic
response is strongly dependent on pulsing conditions and is independent of the total permeabilization achieved by the pulse.
Evidence shows that calorimetry is a simple and powerful method for exploring conditions for metabolic stimulation, providing
information on metabolic responses that can not be obtained from electrical measurements. This study set the basis for further
investigations on defense-related consequences of PEF-induced stress. 相似文献
910.
The intrinsic antiviral defense is based on cellular restriction factors that are constitutively expressed and, thus, active even before a pathogen enters the cell. The promyelocytic leukemia (PML) nuclear bodies (NBs) are discrete nuclear foci that contain several cellular proteins involved in intrinsic antiviral responses against a number of viruses. Accumulating reports have shown the importance of PML as a DNA virus restriction factor and how these pathogens evade this antiviral activity. However, very little information is available regarding the antiviral role of PML against RNA viruses. Dengue virus (DENV) is an RNA emerging mosquito-borne human pathogen affecting millions of individuals each year by causing severe and potentially fatal syndromes. Since no licensed antiviral drug against DENV infection is currently available, it is of great importance to understand the factors mediating intrinsic immunity that may lead to the development of new pharmacological agents that can boost their potency and thereby lead to treatments for this viral disease. In the present study, we investigated the in vitro antiviral role of PML in DENV-2 A549 infected cells. 相似文献