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981.
Jean Charles Leplé Michel Bonadé-Bottino Sylvie Augustin Gilles Pilate Véronique Dumanois Lê Tân André Delplanque Daniel Cornu Lise Jouanin 《Molecular breeding : new strategies in plant improvement》1995,1(4):319-328
The aim of this study was to test the potential of proteinase inhibitors to controlChrysomela tremulae, a beetle that causes severe damage in young plantations and in short-rotation intensive culture (SRIC) of poplar. As a first step, cysteine proteinases were determined to be the major digestive proteinases ofC. tremulae and oryzacystatin OCI, a cysteine proteinase inhibitor, was shown to inhibit this activityin vitro. The gene encoding OCI was introduced into poplar (Populus tremula ×P. tremuloides) and transgenic plants expressing OCI at a high level were selected. Feeding tests on these transgenic plants demonstrate the toxicity of OCI-producing poplar leaves againstC. tremulae larvae.J.C. Leplé and M. Bonadé-Bottino contributed equally to the research presented in this paper. 相似文献
982.
Mark C. Keese 《Oecologia》1997,112(1):81-86
This paper examines the role of predation and parasitism in the host specialization of two chrysomelid beetles that are monophagous
on different species of Asteraceae. Ophraella notulata and O. slobodkini are sister taxa that feed on Iva frutescens and Ambrosia artemisiifolia respectively. Ambrosia is the purported ancestral host plant for this species pair. The question addressed is whether there is evidence that escape
to enemy-free space may influence the host specialization of O. notulata on I. frutescens. I estimated egg predation, successful egg hatch, and larval parasitism directly, and larval predation indirectly, based
on relative abundances of predatory insects and spiders. Egg predation was significantly higher on O. slobodkini and this was not due to species-specific differences in egg defense. However, egg hatch was not significantly different between
O. notulata and O. slobodkini. Predatory arthropods were 4 times more abundant in A. artemisiifolia habitat than in I. frutescens habitat. Interestingly, larval parasitism by a tachinid fly was significantly greater on O. notulata than on O. slobodkini, opposite to the egg predation data and the inferred larval predation rate. There is little evidence to suggest that escape
to enemy-free space is a factor that maintains the monophagy of O. notulata.
Received: 6 January 1995 / Accepted: 14 April 1997 相似文献
983.
The influence of outcrossing and pollination biology on the maintenance of hermaphroditism was studied for Schiedea lydgatei (Caryophyllaceae: Alsinoideae), a species endemic to Moloka`i in the Hawaiian Islands. Schiedea lydgatei is the only hermaphroditic species in an otherwise dimorphic clade and hermaphroditism is likely the result of a reversal from a gynodioecious ancestor. Both wind and native moths in the family Pyralidae are responsible for pollination in S. lydgatei. Outcrossing rates were generally high (0.80), especially in years when the greatest number of plants were flowering. The combination of high outcrossing rates and substantial inbreeding depression indicates that at present females would not be favored in the population. Pollination by both wind and insects is consistent with the hypothesis that hermaphroditism is the result of a relatively recent reversal, as the ancestor of S. lydgatei was probably wind pollinated and gynodioecious with few females in the populations. A shift from wind to predominately insect pollination on Moloka`i may have resulted in increased outcrossing rates and prevented the expression of high inbreeding depression among progeny of hermaphrodites, a condition that would select against females and favor a reversal to hermaphroditism. Because few females were likely to have been present in ancestral populations that colonized Moloka`i, founder effect is another potential explanation for loss of females. In either case, current high levels of outcrossing prevent re-establishment of females in populations of S. lydgatei. 相似文献
984.
David J. Hawthorne 《Evolution; international journal of organic evolution》1997,51(1):153-162
Environmental heterogeneity has often been implicated in the maintenance of genetic variation. However, previous research has not considered how environmental heterogeneity might affect the rate of adaptation to a novel environment. In this study, I used an insect-plant system to test the hypothesis that heterogeneous environments maintain more genetic variation in fitness components in a novel environment than do uniform environments. To manipulate recent ecological history, replicate populations of the dipteran leafminer Liriomyza trifolii were maintained for 20 generations in one of three treatments: a heterogeneous environment that contained five species of host plant, and two uniform environments that contained either a susceptible chrysanthemum or tomato. The hypothesis that greater genetic variance for survivorship and developmental time on a new host plant (a leafminer-resistant chrysanthemum) would be maintained in the heterogeneous treatment relative to the uniform environments was then tested with a sib-analysis and a natural selection experiment. Populations from the heterogeneous host plant treatment had no greater genetic variance in either larval survivorship or developmental time on the new host than did populations from either of the other treatments. Moreover, the rate of adaptation to the new host did not differ between the ecological history treatments, although the populations from the uniform chrysanthemum treatment had higher mean survivorship throughout the selection experiment. The estimates of the heritability of larval survivorship from the sib-analysis and selection experiment were quite similar. These results imply that ecologically realistic levels of environmental heterogeneity will not necessarily maintain more genetic variance than uniform environments when traits expressed in a particular novel environment are considered. 相似文献
985.
J W A SCHEEPMAKER F P GEELS P H SMITS L J L D VAN GRIENSVEN 《The Annals of applied biology》1997,131(3):359-368
The nematode Steinernema feltiae (Nematoda: Steinemematidae) was tested for its ability to control two main mushroom pests i.e. the sciarid Lycoriella auripila (Diptera: Sciaridae) and the phorid Megaselia halterata (Diptera: Phoridae) in growing-rooms filled with spawned compost. A clear difference between female and male sciarid control was observed. A nematode application 1 day after casing preceded by an application 1 day before casing on the compost caused an almost complete control (97%) of the F1-generation of female sciarids. The F2-generation of females was similarly controlled (95%) by an application 7 days after casing. A dosage of 1 × 106nematodes m-2was found to be equally effective as higher dosages. Diflubenzuron remained active throughout entire the cropping period with high sciarid mortality rates varying from 72% to 99%. Phorid control was variable and seemed to depend on the presence of sciarids. In one occasion the control rate of F2-generation phorid larvae was 75% and was possibly caused by the presence of new infective juvenile nematodes recycled in F2-generation sciarid larvae. Diflubenzuron did not significantly reduce phorid numbers. 相似文献
986.
昆虫生态地理学与入侵危险性害虫控制 总被引:4,自引:0,他引:4
昆虫的起源、地质变动、气候、生态环境以及人类活动对昆虫的分布有极其重要的影响.昆虫生态地理学是从种的生态学来阐明昆虫地理分布的规律性的科学,它是害虫检疫的重要基础,在入侵危险性害虫种的鉴定、适生性分析和控制策略特别是生物防治策略的制定等方面有广泛的应用 相似文献
987.
Hamed Doostdar T.Gregory McCollum Richard T Mayer 《Comparative biochemistry and physiology. Part B, Biochemistry & molecular biology》1997,118(4):861-867
An endo-polygalacturonase (PG) (EC:3.2.1.15) with a pI of 9.4 and an Mr of 44,500 was purified to electrophoretic homogeneity from the gut of West Indies sugarcane rootstalk borer weevil (Diaprepes abbreviatus L.) larvae. Hydrolytic activity was maximal in 150 mM sodium acetate, pH 5.5, at 30°C. Kinetic determinations yielded an apparent Km of 3.68 mg polygalacturonic acid (PGA)/ml and a Vmax of 283 μmol galacturonic acid/min/mg protein for PGA. Enzymatic activity was inhibited by a polygalacturonase inhibitor protein from “Hamlin” orange flavedo. The purified protein does not appear to be glycosylated, and its N-terminal sequence showed no homology to any PG protein sequences in data banks. 相似文献
988.
Zdeněk Wimmer Richard Tykva Blanka Bennettová Věra Vlasáková Tomáš Elbert 《Invertebrate neuroscience : IN》1997,3(2-3):193-197
A synthetic insect juvenile hormone analog (a juvenoid), ethylN-[2-[4-[[2,2-(ethylenedioxy)cyclohexyl]methyl]phenox]ethyl]carbamate, which has displayed high biological activity against
different insect species and high stability under field conditions, was selected as a biologically active model compound for
a study of a juvenile hormone analog degradation. The biologically active compound itself and its three diversely radiolabeled
derivatives were applied to the flesh fly (Sarcophaga bullata) or the tsetse fly (Glossina palpalis), respectively. Monitoring of a fate of the applied juvenile hormone analog was carried out using a detection method of the
radioactivity microdistribution within the whole insect body in combination with a radio high performance liquid chromatography
(radio-HPLC), both of whole-body extracts made in different, but in advance scheduled, time intervals, and of extracts of
insect excreta accumulated over an eight-day experiment. 相似文献
989.
Abstract This field study was designed to test whether the taxonomic group and geographic range size of a host plant species, usually found to influence insect species richness in other parts of the world, affected the number of gall species on Australian eucalypts. We assessed the local and regional species richness of gall-forming insects on five pairs of closely related eucalypt species. One pair belonged to the subgenus Corymbia, one to Monocalyptus, and three to different sections of Symphyomyrtus. Each eucalypt pair comprised a large and a small geographic range species. Species pairs were from coastal or inland regions of eastern Australia. The total number of gall species on eucalypt species with large geographic ranges was greater than on eucalypt species with small ranges, but only after the strong effect of eucalypt taxonomic grouping was taken into account. There was no relationship between the geographic range size of eucalypt species and the size of local assemblages of gall species, but the variation in insect species composition between local sites was higher on eucalypt species with large ranges than on those with small ranges. Thus the effect of host plant range size on insect species richness was due to greater differentiation between more widespread locations, rather than to greater local species richness. This study confirms the role of the geographic range size of a host plant in the determination of insect species richness and provides evidence for the importance of the taxon of a host plant. 相似文献
990.
Andrew S. Pullin 《Journal of Insect Conservation》1997,1(3):177-185
This paper reports on studies of the habitat requirements of Lycaena dispar batavus in its largest remaining site, the Weerribben National Park in the Netherlands. Observations and experiments were carried out to assess requirements for male territories, egg-laying sites and larval survival. The management of the fenland was also assessed on a landscape scale. Male territories were all situated in summer cut fen meadow. Eggs were laid on Rumex hydrolapathum in a range of habitat situations, although a preference was shown for plants on fen edges. Larval survival was highest on plants on watersides and fen edges, with no survival on plants in summer cut fen meadow. The findings are discussed in relation to whether the Broadland area in eastern England is suitable as a re-establishment site. Although many elements of the habitat mosaic are present, at the landscape scale there is insufficient open fenland and areas suitable for male territories are probably too isolated; however, a fen restoration strategy is in place which may restore suitable habitat and make re-establishment feasible in the future. 相似文献