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61.
62.
A. V. Naumenko G. N. Kovalev V. Yu. Naumenko E. I. Zaraisky N. S. Snegireva 《Biophysics》2006,51(2):209-214
The interactions of model proteins with porous matrices in biosensors are considered. The viscoelastic properties of casein and albumin were assessed by a dynamic method of a piezoquartz resonator by applying thin layers of the studied solutions to a piezocrystal. The experimental data on the viscoelastic characteristics of protein solutions of various concentrations were compared with the characteristics of their tangential motion in the porous carriers of cellulose nitrate. It was demonstrated that the parameters of dynamic viscosity correlated with the motion time of the protein solutions in the porous polymeric carrier. 相似文献
63.
Iain J. Mcgaw 《Marine and Freshwater Behaviour and Physiology》2006,39(2):131-141
Cardiovascular and respiratory variables were recorded in the blue crab, Callinectes sapidus, during injury and subsequent autotomy of a chela. Cardiac function and haemolymph flow rates were measured using a pulsed-Doppler flowmeter. Oxygen uptake was recorded using an intermittent flow respirometry system. Crabs reacted to the loss of a chela with a rapid increase in heart rate, which was sustained for 2 h. Stroke volume of the heart also increased after the chela was autotomized. A combined increase in heart rate and stroke volume led to an increase in cardiac output, which was maintained for an hour after the loss of a chela. There was also differential haemolymph perfusion of various structures. There was no change in perfusion of the anterolateral arteries or posterior and anterior aortae, during injury of the chela or subsequent autotomy. Haemolymph flow rates did increase significantly through the sternal artery during injury and immediately following autotomy of the chela. This was at the expense of blood flow to the digestive gland: a sustained decrease in haemolymph flow through the hepatic arteries occurred for 3 h following autotomy. Fine-scale cardiac changes associated with the act of autotomy included a bradycardia and/or associated cardiac pausing before the chela was shed, followed by a subsequent increase in cardiac parameters. Changes in the cardiovascular physiology were paralleled by an increase in oxygen uptake, which was driven by an increased ventilation of the branchial chambers. Although limb loss is a major event, it appears that only acute changes in physiology occur. These may benefit the individual, allowing rapid escape following autotomy with a subsequent return to normal activity. 相似文献
64.
The synthesis and characterization of rare-earth (La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu and Y) thiocyanate adducts with tripiperidinophosphine oxide (tpppO) with general formula (RE)(SCN)3(tpppO)3 are reported. Conductance measurements in acetonitrile indicate the non-electrolytic nature of the complexes. Infrared absorption spectra evidence that the SCN− ion coordinates through the nitrogen atom (isothiocyanate form) and that tpppO coordinates through the phosphoryl oxygen. X-ray powder patterns suggest the existence of three different crystal forms: (1) La; (2) an isomorphous series including Ce, Nd and Pr; and (3) another isomorphous series, including Sm, Gd, Eu, Ho, Er, Tb, Lu and Y. The visible spectra of the Nd adduct and the calculated parameters β = 0.98, b1/2 = 0.072 and δ = 1.06 indicate that the metal-ligand bonds are essentially electrostactic. The emission spectra of the Eu compound showed 5D0 → 7FJ bands (J = 0, 1, 2), suggesting a C3v symmetry for the coordination polyhedron. The lifetime of the 5D0 state is 1.28 ms. The emission spectra of the Tb complex presented 5D4 → 7FJ bands (J = 4, 5, 6) and the Dy complex showed the 4F9/2 → 6H13/2 band. The structure of the Pr complex showed that the coordination polyhedron is a trigonal antiprism, with the isothiocyanate anions in one base and three tpppO ligands in the other. Thermal analyses (TG-DTG) were carried out for the Ce, Nd and Gd adducts. Mass losses start between 250 and 334 °C. The final residues at 1300 °C are the corresponding phosphates. 相似文献
65.
Spatial distribution of ant workers and, notably their aggregation/segregation behaviour, is a key-element of the colony social
organization contributing to the efficiency of task performance and division of labour. In polymorphic species, specialized
worker castes notably differ in their intrinsic aggregation behaviour. In this context, knowing the preponderant role of minors
in brood care, we investigate how a stimulus such as brood can influence the spatial patterns of Pheidole pallidula worker castes. In a homogeneous area without brood, it was shown that minors display only a low level of aggregation while
majors form large clusters in the central area. Here we find out that these aggregation patterns of both minors and majors
can be deeply influenced by the presence of brood. For minors, it nucleates or enhances the formation of a large stable cluster.
Such high sensitivity of minors to brood stimuli fits well with their role as main brood tenders in the colony. For majors,
interattraction between individuals still remains the prevailing aggregation factor while brood strongly influences the localisation
of their cluster. We discuss how the balance between interattraction and sensitivity to environmental stimuli determines the
mobility of each worker castes and, consequently, the availability of minors and majors to participate in everyday colony
tasks. Moreover, we will evoke the functional value of majors’ cluster location close to the brood, namely with respect to
social regulation of the colony caste ratio.
Received 30 May 2005; revised 11 January 2006; accepted 13 January 2006. 相似文献
66.
Facultative joint colony founding by social insects (pleometrosis) provides an outstanding opportunity to analyze the costs
and benefits of sociality. Pleometrosis has been documented for a range of social insects, but most studies on the adaptive
benefits of this behavior are restricted to the Hymenoptera. In this study, we provide the first analysis of costs and benefits
associated with pleometrosis for Australian Dunatothrips, which form domiciles by glueing together phyllodes (leaves) of their Acacia host plant. In Dunatothrips aneurae, the distribution of foundress numbers per nest indicated that females formed associations non-randomly. Furthermore, average
group size was independent of both the number of foundresses on the host plant and the number of mature colonies, suggesting
that this behavior was not simply a response to limited availability of nesting sites. Although per capita reproduction declined
with increasing group size, we also identified two benefits of pleometrosis: (1) individual foundresses in groups had higher
survival than solitary foundresses during the brood development period, and (2) larger colony sizes resulting from pleometrosis
provided a benefit later in colony development, because a higher proportion of D. aneurae adults survived invasions by the kleptoparasite Xaniothrips mulga when colony size was larger. These results demonstrate that the reproductive costs of pleometrosis are at least partially
counterbalanced by survival benefits.
Received 4 April 2006; revised 9 September 2006; accepted 20 September 2006. 相似文献
67.
Respiration, which is the second most important carbon flux in ecosystems following gross primary productivity, is typically represented in biogeochemical models by simple temperature dependence equations. These equations were established in the 19th century and have been modified very little since then. Recent applications of these equations to data on soil respiration have produced highly variable apparent temperature sensitivities. This paper searches for reasons for this variability, ranging from biochemical reactions to ecosystem‐scale substrate supply. For a simple membrane‐bound enzymatic system that follows Michaelis–Menten kinetics, the temperature sensitivities of maximum enzyme activity (Vmax) and the half‐saturation constant that reflects the affinity of the enzyme for the substrate (Km) can cancel each other to produce no net temperature dependence of the enzyme. Alternatively, when diffusion of substrates covaries with temperature, then the combined temperature sensitivity can be higher than that of each individual process. We also present examples to show that soluble carbon substrate supply is likely to be important at scales ranging from transport across membranes, diffusion through soil water films, allocation to aboveground and belowground plant tissues, phenological patterns of carbon allocation and growth, and intersite differences in productivity. Robust models of soil respiration will require that the direct effects of substrate supply, temperature, and desiccation stress be separated from the indirect effects of temperature and soil water content on substrate diffusion and availability. We speculate that apparent Q10 values of respiration that are significantly above about 2.5 probably indicate that some unidentified process of substrate supply is confounded with observed temperature variation. 相似文献
68.
Susan Leekam 《Philosophical transactions of the Royal Society of London. Series B, Biological sciences》2016,371(1686)
Early psychological theories of autism explained the clinical features of this condition in terms of perceptual and sensory processing impairments. The arrival of domain-specific social cognitive theories changed this focus, postulating a ‘primary’ and specific psychological impairment of social cognition. Across the years, evidence has been growing in support of social cognitive and social attention explanations in autism. However, there has also been evidence for general non-social cognitive impairments in representational understanding, attention allocation and sensory processing. Here, I review recent findings and consider the case for the specificity and primacy of the social cognitive impairment, proposing that we should focus more explicitly on clinically valid features for insights on the integration of ‘social’ and ‘non-social’ cognition. 相似文献
69.
A three-dimensional operational hydrodynamic model, developed at the Institute of Oceanography, University of Gdańsk was used
to forecast hydrological conditions in the Oder Estuary. The model was based on the coastal ocean circulation model known
as the Princeton Ocean Model (POM). Because of wind-driven water backup in the Oder mouth, a simplified operational model
of river discharge, based on water budget in a stream channel, was developed. Linking these two models into a single system
made it possible to forecast water levels, currents, water temperature, and salinity in the estuary. A good fit between the
observed and computed data allowed to consider the model as a reliable environmental tool. Obtaining a hydrological forecast
via a quick website access gives potential users an opportunity to predict the day-by-day course of processes that may affect
different areas of human life and activities, e.g., navigation, port operations, flood protection of coastal areas; the predictions
may also be used in studies of coastal processes in the estuary. 相似文献