篇章类英语试题的考点效度验证

在我国大规模英语考试试卷中基于篇章类的试题占相对比较高的比例,其考点效度关乎整份试卷的效度。本文通过对篇章类英语试题考点所属构念效度的例析,说明从考点层面所获取的相关效验证据对基于篇章类试题的考点效度进行了有效验证。     

Osmotic pressure influence in germination tests for antibiosis

A common test for the presence of toxic organic substances in plant tissues, and therefore of the potential role of antibiosis (specifically allelopathy) in native plant cozmmunities, has been to apply a water extract of the tissues in germination tests of cultivated annuals. The observed osmotic pressure of the extracts can be high, and sucrose solutions of similar osmotic pressure result in a depression of germnination and early development. Thus in the aforementioned type of test, extracts must be diluted to an osmotic pressure no greater than 0.5 atmopheres.     

Cyclic adenosine monophosphate phosphodiesterase in brain: effect on anxiety

Drugs that reduce anxiety may be mediated by cyclic adenosine monophosphate in the brain because (i) potent anxiety-reducing drugs are also potent inhibitors of brain phosphodiesterase activity; (ii) dibutyryl cyclic adenosine monophosphate has the ability to reduce anxiety; (iii) the methylxanthines show significant anxiety-reducing effects; (iv) theophylline and chlordiazepoxide produce additive anxiety-reducing activity; and (v) there is a significant correlation between the anxiety-reducing property of drugs and their ability to inhibit phosphodiesterase activity in the brain.     

Environment

In contrast to the approaches to resource management and preservation of the past decade, a new perspective on environmental problems is emerging. Six major trends in scientific thinking are (i) increased efforts to examine environments In holistic frameworks, (ii) greater attention to life support systems, (iii) enlarged canvass of the range of choices in resource management, (iv) refinement in methods of risk assessment, (v) streamlined methods for monitoring environmental change, and (vi) more emphasis on the global framework.     

Complex species interactions and the dynamics of ecological systems: long-term experiments

Studies that combine experimental manipulations with long-term data collection reveal elaborate interactions among species that affect the structure and dynamics of ecosystems. Research programs in U.S. desert shrubland and pinyon-juniper woodland have shown that (i) complex dynamics of species populations reflect interactions with other organisms and fluctuating climate; (ii) genotype x environment interactions affect responses of species to environmental change; (iii) herbivore-resistance traits of dominant plant species and impacts of "keystone" animal species cascade through the system to affect many organisms and ecosystem processes; and (iv) some environmental perturbations can cause wholesale reorganization of ecosystems because they exceed the ecological tolerances of dominant or keystone species, whereas other changes may be buffered because of the compensatory dynamics of complementary species.     

Carbonate Rocks: Cleaning with Suspensions of Hydrogen-Ion Exchange Resin

The surface of carbonate rocks may be cleaned by etching or polishing or both, with hydrogen-ion exchange resin. This treatment reveals details in texture and fossil morphology so clearly that thin sections may be often dispensed with. Of four cleaning methods, (i) allowing resin to settle around the sample, (ii) stirring with a magnetic stirrer, (iii) agitating with an ultrasonic generator, and (iv) directing a jet stream at the sample, the first method was best for large specimens and the second method was best for well cuttings and chips.     

Bio-organic compounds and glassy microparticles in lunar fines and other materials

Acid hydrolyzates of aqueous extracts indicated: glycine, alanine, glutamic acid, serine, aspartic acid, threonine, and I-diaminopropionic acid. The sources of these amino acids may be terrestrial contaminants, fuel exhaust products, or indigenous lunar material. The lunar particles found in the sample include: (i) spherules, rotational ellipsoids, dumbbells, tear-drops, rings, and crescents which have (ii) diameters of 0.1 to 500 microns; (iii) budlike features on the particles; and (iv) chemical inhomogeneity (electron probe). Some of the processes and results inferred for the moon have been simulated by the electron beam and low pressure of the electron microscope. Basalt (Kilauea-lki) and chondrite (Orgueil) have been found to behave similarly.     

A primitive enantiornithine bird and the origin of feathers

A fossil enantiornithine bird, Protopteryx fengningensis gen. et sp. nov., was collected from the Early Cretaceous Yixian Formation of Northern China. It provides fossil evidence of a triosseal canal in early birds. The manus and the alular digit are long, as in Archaeopteryx and Confuciusornis, but are relatively short in other enantiornithines. The alula or bastard wing is attached to an unreduced alular digit. The two central tail feathers are scalelike without branching. This type of feather may suggest that modern feathers evolved through the following stages: (i) elongated scale, (ii) central shaft, (iii) barbs, and finally (iv) barbules and barbicel.     

Hot-spot evolution and the global tectonics of venus

The global tectonics of Venus may be dominated by plumes rising from the mantle and impinging on the lithosphere, giving rise to hot spots. Global sea-floor spreading does not take place, but direct convective coupling of mantle flow fields to the lithosphere leads to regional-scale deformation and may allow lithospheric transport on a limited scale. A hot-spot evolutionary sequence comprises (i) a broad domal uplift resulting from a rising mantle plume, (ii) massive partial melting in the plume head and generation of a thickened crust or crustal plateau, (iii) collapse of dynamic topography, and (iv) creep spreading of the crustal plateau. Crust on Venus is produced by gradual vertical differentiation with little recycling rather than by the rapid horizontal creation and consumption characteristic of terrestrial sea-floor spreading.     

Electron observations and ion flows from the pioneer venus orbiter plasma analyzer experiment

Additional plasma measurements in the vicinity of Venus are presented which show that (i) there are three distinct plasma electron populations-solar wind electrons, ionosheath electrons, and nightside ionosphere electrons; (ii) the plasma ion flow pattern in the ionosheath is consistent with deflected flow around a blunt obstacle; (iii) the plasma ion flow velocities near the downstream wake may, at times, be consistent with the deflection of plasma into the tail, closing the solar wind cavity downstream from Venus at a relatively close distance (within 5 Venus radii) to the planet; (iv) there is a separation between the inner boundary of the downstream ionosheath and the upper boundary of the nightside ionosphere; and (v) during the first 4.5 months in orbit the measured solar wind plasma speed continued to vary, showing a number of high-speed, but generally nonrecurrent, streams.     

Sound velocity and compressibility for lunar rocks 17 and 46 and for glass spheres from the lunar soil

Four experiments on lunar materials are reported: (i) resonance on glass spheres from the soil; (ii) compressibility of rock 10017; (iii) sound velocities of rocks 10046 and 10017; (iv) sound velocity of the lunar fines. The data overlap and are mutually consistent. The glass beads and rock 10017 have mechanical properties which correspond to terrestrial materials. Results of (iv) are consistent with low seismic travel times in the lunar maria. Results of analysis of the microbreccia (10046) agreed with the soil during the first pressure cycle, but after overpressure the rock changed, and it then resembled rock 10017. Three models of the lunar surface were constructed giving density and velocity profiles.     

Deep Impact: observations from a worldwide Earth-based campaign

On 4 July 2005, many observatories around the world and in space observed the collision of Deep Impact with comet 9P/Tempel 1 or its aftermath. This was an unprecedented coordinated observational campaign. These data show that (i) there was new material after impact that was compositionally different from that seen before impact; (ii) the ratio of dust mass to gas mass in the ejecta was much larger than before impact; (iii) the new activity did not last more than a few days, and by 9 July the comet's behavior was indistinguishable from its pre-impact behavior; and (iv) there were interesting transient phenomena that may be correlated with cratering physics.     

玉米芯生料栽培平菇高产技术试验

将玉米芯粉碎成大豆粒大小颗粒，加入适量麸皮、尿素、磷肥等辅料，料水比１∶１８，拌料堆焖２４小时，接种量２０％～２５％，并采用改进的接种方法，微孔发菌，大棚覆土等配套措施栽培平菇，发菌成功率达９９％，生物效率达１５０％。     

Evidence and implications of shock metamorphism in lunar samples

Lunar microbreccias and loose regolith materials contain abundant evidence of shock metamorphism related to crater-forming meteorite impacts. Diagnostic shock effects include (i) planar features in a silica phase and feldspars, and lamellae in clinopyroxene, (ii) thetomorphic feldspar glass, (iii) heterogeneous glasses of rock and mineral composition, (iv) distinctive recrystallization textures, and (v) characteristic changes in crystal structure as indicated by x-ray diffraction analysis and measurements of refractive index. The microbreccias are produced from regolith materials (ejected fromz craters) by shock lithification. Some feldsparrich fragments may represent ejecta introduced from nonlocal sources, such as the lunar highlands.     

Nutrient cycling

The small-watershed approach to problems of nutrient cycling has these advantages. (i) The small watershed is a natural unit of suitable size for intensive study of nutrient cycling at the ecosystem level. (ii) It provides a means of reducing to a minimum, or virtually eliminating, the effect of the difficult-to-measure variables of geologic input and nutrient losses in deep seepage. Control of these variables makes possible accurate measurement of nutrient input and output (erosion) and therefore establishes the relationship of the smaller ecosystem to the larger biospheric cycles. (iii) The small-watershed approach provides a method whereby such important parameters as nutrient release from minerals (weathering) and annual nutrient budgets may be calculated. (iv) It provides a means of studying the interrelationships between the biota and the hydrologic cycle, various nutrient cycles, and energy flow in a single system. (v) Finally, with the small-watershed system we can test the effect of various land-management practices or environmental pollutants on nutrient cycling in natural systems.     

Ryanodine receptor of skeletal muscle is a gap junction-type channel

In the sarcoplasmic reticulum membrane of skeletal muscle, the ryanodine receptor forms an aqueous pore identified as the calcium-release pathway that operates during excitation-contraction coupling. The purified ryanodine receptor channel has now been shown to have four properties usually associated with gap junction channels: (i) a large nonspecific voltage-dependent conductance consisting of several open states; (ii) an inhibition of open probability by low pH; (iii) an inhibition of open probability by calcium; and (iv) a sensitivity to blockade by heptanol and octanol but not other alcohols. This functional homology may provide an insight into the mechanism of how muscle cells transduce depolarization into an intracellular release of calcium.     

Archean microfossils showing cell division from the swaziland system of South Africa

A newly discovered population of organic walled microstructures from the Swaziland System, South Africa, is considered to be biological on the following grounds: (i) the structures are carbonaceous and occasionally have internal organic contents; (ii) the population has a narrow unimodal size frequency distribution (average diameter, 2.5 micrometers; range, 1 to 4 micrometers); (iii) the structures are not strictly spherical, but are commonly flattened and folded like younger microfossils; (iv) the sedimentary context is consistent with biogenic origins; and (v) various stages of binary division are clearly preserved.     

Trends in computers and computing: the information utility

Demands for more effective information management, coupled with advances in computer hardware and software technology, have resulted in the emergence of the information utility concept, whereby computers specialized for information storage and processing serve as information nodes. The information nodes, which may be interconnected, can provide information management services to both conventional and personal computers. In this article the key hardware and software components of classical information systems are described to provide background on the requirements for an information utility. Four approaches to the development of specialized information nodes, drawing on various advances in technology, are presented: (i) firmware enhancement, (ii) intelligent controllers, (iii) minicomputer back-end processors, and (iv) highly modular database machines. The benefits of these advances will be systems that are more efficient, reliable, and easy to use.     

Ethical dilemmas in agriculture: The need for recognition and resolution

Agricultural research and education ended 100 years of funding under the Hatch Act with a decade of unprecedented criticism of goals and outcomes. This paper examines the way that planners can accommodate some of these criticisms within a framework for understanding the ethical and social goals of agriculture that is consistent with traditional practice. The paper goes on to state that some criticisms are so fundamental that they cannot be readily incorporated into this framework. They must be regarded as a challenge, both politically and intellectually, to longstanding practices within academic institutions devoted to agriculture.