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931.
Two simultaneous distribution free test procedures to test the homogeneity of K samples of response curves measured at T points of time each are proposed which react upon the shape of the response curve. One procedure is based on the comparison of K T-tupels of FRIEDMAN-rank sums, the other on the comparison of K T × T-incidence tables, which first were introduced by KANNEMANN (1976). The application of the two procedures is illustrated by a numerical example. In the discussion the tests are compared with each other and with concurring tests. 相似文献
932.
B. S. Goel 《Biometrical journal. Biometrische Zeitschrift》1980,22(4):351-358
Extreme Vertices designs were developed by MCLEAN and ANDERSON (1966) for situations where components of a mixture are restricted by lower and upper bounds, SNEE and MARQUARDT (1974) and SNEE (1975) gave algorithms to construct optimum designs in these situations. SAXENA and NIGAM (1975) evolved a transformation which provides designs for restricted exploration using Symmetric Simplex designs. In this paper a procedure has been given which provides alternative designs with uniform exploration in constrained mixture experiments. The procedure is illustrated by an example. 相似文献
933.
David Pignol Jay A. Bertrand Jean-Paul Bernard Jean-Michel Verdier Jean-Charles Dagorn Juan Carlos Fontecilla-Camps 《Proteins》1995,23(4):604-606
Crystals of human lithostathine, a pancreatic glycoprotein which inhibits the growth and nucleation of calcium carbonate crystals, were grown using PEG 4000 as the precipitating agent. The crystals belong to the hexagonal space group P61 (or its enantiomorph P65) and diffract to 1.55 Å resolution. There is one molecule in the asymmetric unit and the crystals have 39% solvent. © 1995 Wiley-Liss, Inc. 相似文献
934.
In this paper sequential exploration of response surfaces for mixture experiments has been studied. The plan and the estimation and testing procedures for some of the well known models have been given. 相似文献
935.
Peter Schmieder Alan S. Stern Gerhard Wagner Jeffrey C. Hoch 《Journal of biomolecular NMR》1994,4(4):483-490
Summary Nonlinear sampling along the constant-time dimension is applied to the constant-time HNCO spectrum of the dimerization domain of Ga14. Nonlinear sampling was used for the nitrogen dimension, while the carbon and proton dimensions were sampled linearly. A conventional ct-HNCO spectrum is compared with a nonlinearly sampled spectrum, where the gain in experiment time obtained from nonlinear sampling is used to increase the resolution in the carbonyl dimension. Nonlinearly sampled data are processed by maximum entropy reconstruction. It is shown that the nonlinearly sampled spectrum has a higher resolution, although it was recorded in less time. The constant intensity of the signal in the constant-time dimension allows for a variety of sampling schedules. A schedule of randomly distributed sampling points yields the best results. This general method can be used to significantly increase the quality of heteronuclear constant-time spectra. 相似文献
936.
J. ROSEWELL B. SHORROCKS 《Biological journal of the Linnean Society. Linnean Society of London》1987,32(4):373-384
Adult survival rates were estimated in field populations of domestic Drosophila species by means of multiple capture-recapture experiments. Micronized fluorescent dusts were used as marking agents and analysis used the Fisher-Ford model: the assumptions of this model are justified using evidence from this study and the literature. Survival rates were commonly 0.45-0.85 per day, suggesting that mean life expectancy for adult flies is from 1.3 to 6.2 days in natural populations. No consistent differences in survival between sexes or seasons were demonstrated. The implications of low natural survival rates are discussed. 相似文献
937.
Magali Zbinden Bruce Shillito Constance de Villardi de Montlaur François Guyot Marie-Anne Cambon-Bonavita 《Journal of experimental marine biology and ecology》2008,359(2):131-140
The Rimicaris exoculata dominates the megafauna of some of the Mid Atlantic ridge hydrothermal vent sites. This species harbors a rich community of bacterial epibionts inside its gill chamber. Literature data indicate that a single 16S rRNA phylotype dominates this epibiotic community, and is assumed to be a sulfide-oxidizing bacteria. However attempts of cultivation were not successful and did not allow to confirm it. The aim of our study was to test the hypothesis of sulfide oxidation in the gill chamber, by a multidisciplinary approach, using in vivo experiments at in situ pressure in the presence of sulfide, microscopic observations and a molecular survey. Morphology of microorganisms, before and after treatment, was analyzed to test the effect of sulfide depletion and re-exposure. Our observations, as well as molecular data indicate a wider diversity than previously described for this shrimp's epibiotic community. We observed occurrence of bacterial intracellular sulfur- and iron-enriched granules and some methanotrophic-like bacteria cells for the first time. Genes that are characteristic of methane-oxidizing (pmoA) and sulfide-oxidizing (APS) bacteria were identified. These results suggest that three metabolic types (iron, sulfide and methane oxidation) may co-occur within the epibiont community associated with Rimicaris exoculata. As this shrimp colonizes chemically contrasted environments, the relative abundance of each metabolic type could vary according to the local availability of reduced compounds. 相似文献
938.
939.
Edmund Priddis Russell Rader Mark Belk Bruce Schaalje Steven Merkley 《Diversity & distributions》2009,15(4):682-691
Aim Western mosquitofish (Gambusia affinis) have been linked with the decline of native fish and amphibians throughout the world. Separation along the temperature niche axis may promote the long‐term coexistence of introduced western mosquitofish, with native species in temperate regions. Recent research has shown that western mosquitofish can reduce the recruitment of native least chub (Iothichthys phlegethontis) endemic to the Bonneville Basin. We tested the hypotheses that cold temperatures (≤ 15 °C in the summer, freezing winters) would: (1) reduce the aggressive and predatory effects of western mosquitofish on least chub, and (2) eliminate the overwinter survival and recruitment of western mosquitofish while having little effect on least chub recruitment. Location Bonneville Basin of Utah, USA. Methods We used short‐term tests in the laboratory at the level of individuals and manipulated temperature (warm, cold and seasonal treatments) in long‐term experiments using mesocosms at the population level. Results Cold temperatures (≤ 15 °C) reduced the aggression and predation of western mosquitofish on least chub at the level of individuals. At the population level, however, cool summers (≤ 15 °C) eliminated recruitment in both species because they required warm summers (c. 20–30 °C) to survive freezing winters. Although least chub had an overwinter advantage in survival (75% least chub, 45% western mosquitofish), it was overwhelmed by the rapid reproduction of western mosquitofish as temperatures increased in the summer. Main conclusions Studies at the level of populations are necessary to understand the ultimate effects of introduced species on native taxa. Separation along the temperature niche axis was not sufficient to promote coexistence between these species in habitats with warm summers (c. 30 °C). Although coexistence may be possible in habitats with cool summers (≤ 20 °C) and freezing winters, the ability of niche separation to promote long‐term coexistence between native and introduced species may ultimately depend on their respective rates of evolution. Long‐term coexistence may not be possible if introduced species can adapt to new environmental conditions faster than native species can evolve mechanisms to reduce their harmful effects. 相似文献
940.
David W. Schindler 《Ecosystems》1998,1(4):323-334
The results of bottle and mesocosm experiments were compared with those obtained in whole-ecosystem experiments at the Experimental
Lakes Area. Unless they can be cleverly designed to mimic major ecosystem processes and community compositions, smaller-scale
experiments often give highly replicable, but spurious, answers. Problems with appropriate scaling are difficult to deduce
without direct comparisons with whole-ecosystem experiments. Reasons are many, but include inappropriate spatial scales to
include whole communities, in particular predators and nocturnally active animals; temporal scales that are too short to assess
accurately the response of slow-responding organisms and biogeochemical processes; and elimination of key littoral–pelagic
and catchment–lake interactions. Identical studies of limnological processes in lakes of a large range of sizes reveals that
scaling correction is also necessary when extrapolating from small lakes to large ones. Accurate management decisions cannot
be made with confidence unless ecosystem scales are studied.
Received 26 March 1998; accepted 14 May 1998. 相似文献