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1.
《水生昆虫》2012,34(2):139-155
In the Volga Basin, the small Baikalian amphipod Gmelinoides fasciatus was introduced in 1965 into the Gorky reservoir in order to enhance fish production; it appeared in 1986 in the Rybinsk reservoir and we recorded it during monitoring activities in 2006 at Tver. In total, at the monitoring site Tver/Migalovo 69 benthic invertebrate taxa were identified. We compared data from three summer seasons. During summer low flow period Gmelinoides fasciatus did not exceed a share of 12.6% considering individual (ind) densities (mean abundance 165 ± 104 ind m?2) and 14.2% considering biomass (mean biomass 0.39 ± 0.44 g m?2). Abundances and biomass of G. fasciatus were shown to be stable over three years and no increase was observed. The monthly dataset (March–November 2008) revealed dynamics in relation to the native benthic communities and it was shown that the maximal densities of Gmelinoides did not exceed 587 ind m–2. Understanding the effects on benthic communities caused by the invasive amphipod Gmelinoides fasciatus is crucial in order to predict further developments in European inland waters and to establish management strategies. 相似文献
2.
《Ethnic and racial studies》2012,35(6):971-987
Abstract Deploying liberal multiculturalist discourse, the media depicts professional basketball as a post-racial space where all talented players, regardless of their race, can thrive if they work hard. An analysis of the construction of non-white players in the 1930s and in 2010 demonstrates sport as modulated by racially charged discourse. As part of a liberal multiculturalist frame, the coding of basketball players as hero, threat and novelty serve to privilege whiteness and replicate racialized and gendered images that can be traced to the 1930s. In doing so, the article highlights how liberal multiculturalism involves racial triangulation and the simultaneous processes of hyper-racialization and de-racialization. 相似文献
3.
E. Cortés A.A. Kirk J.A. Goolsby P.J. Moran A.E. Racelis M.A. Marcos-García 《Biocontrol Science and Technology》2011,21(11):1369-1373
Arundo donax L. (Poaceae) is native to Mediterranean Europe and invasive in the Rio Grande Basin of North America. Rhizomes from nine sites in France and Spain infested with a candidate control agent, the armoured scale Rhizaspidiotus donacis (Hemiptera: Diaspididae) weighed 50% less than those from nine sites without scale. 相似文献
4.
Lars-G. Lundin 《Biochemical genetics》1987,25(7-8):603-610
A gene (Bmn) with a major effect on -mannosidase activity in kidney and liver of the house mouse was revealed by assay with the synthetic substratep-nitrophenyl--d-mannoside. Activity is low in DBA/2J and CSB mice and high in C57BL/6J mice. By the use of the BXD series of recombinant inbred strains and by crosses between C57BL and CSB, it was possible to map the gene to the distal part of chromosome 3 by demonstration of linkage to a gene for cadmium resistance,cdm, as well as to theAdh-3 locus.This work was supported by Swedish Natural Science Research Council Project B-BU 2992-108. 相似文献
5.
6.
R L Blakely 《American journal of physical anthropology》1989,80(2):173-185
Because plants and animals consume or absorb different amounts of strontium and calcium, anthropologists are able to use strontium/calcium (Sr/Ca) ratios from archaeologically recovered human bone to estimate the relative contributions of meat and plants to paleodiets. Often females exhibit higher Sr/Ca ratios than males, a fact usually attributed to lower meat intake among women. However, in vivo and in vitro experiments with laboratory animals show that pregnancy and lactation elevate maternal bone strontium and depress maternal bone calcium because 1) strontium is discriminated against in favor of calcium in the transport of ions to the placenta and mammary glands and 2) pregnancy and lactation facilitate absorption of alkaline earth metals from the gut. In this study, bone Sr/Ca ratios and strontium concentrations were compared between reproductive-age females, postmenopausal females, and adult males from two late prehistoric Native American sites in Georgia: the King site (N = 43) and the Etowah site (N = 51). At the King site, the mean Sr/Ca ratio of females was over 14% greater than that of males. At Etowah, the mean strontium level of reproductive-age females exceeded that of postmenopausal females by almost 25%. Most of the difference, it is argued, is due to pregnancy and lactation. A dietary preference among pregnant and lactating women for foods high in alkaline earths, particularly nuts and corn, may also be partially responsible. Until we assess the influence variables other than nutrition exert on trace element concentrations, our reconstructions of paleodiets will be suspect. 相似文献
7.
Quantitative comparison of Fusarium oxysporum competitiveness in relation to carbon utilization 总被引:3,自引:0,他引:3
Abstract The competitive saprophytic interaction between pathogenic and non-pathogenic strains of Fusarium oxysporum was investigated by studying their ability to competitively colonize sterilized soil. It was demonstrated that carbon was the first limiting substrate of Fusarium oxysporum growth in sterilized soil. Moreover, the efficiency with which glucose was utilized in the formation of propagules varied from one strain to another. Results of competitiion experiments showed that a linear relationship existed between the ratio of inoculum densities at the plateau (carrying capacity) and the ratio of inoculum densities incorporated into non-amended sterilized soil. The slope of the regression line indicated the competitiveness index, i.e. the competitiveness of a non-pathogenic strain in relation to that of a pathogenic strain. This parameter could be related to the yield coefficient of the strains in glucose-amended soil. 相似文献
8.
Plasmid content in Yersinia pestis strains of different origin 总被引:5,自引:0,他引:5
Andrew A. Filippov Nikolai S. Solodovnikov Liubov M. Kookleva Olga A. Protsenko 《FEMS microbiology letters》1990,67(1-2):45-48
Plasmid content in 242 Yersinia pestis strains from various natural plague foci of the U.S.S.R. and other countries was studied. Of these strains, 172 (71%) were shown to carry three plasmids described previously of about 6, 45-50 and 60 MDa, respectively. Twenty strains (8%) from different foci harboured additional cryptic plasmids, most often of about 20 mDa in size. Plasmid pPst displayed considerable constancy of its molecular mass. On the contrary, size variations of pCad (45-49 MDa) and, especially, pFra (60-190 MDa) were found. Molecular mass of these plasmids correlated with the host strain origin. 相似文献
9.
Nodules were collected from 14 legume species from the Indonesian Islands of South Sulawesi, Java and Sumatra. Their rhizobia
were isolated and growth characteristics, nodulation ability and nitrogen fixing effectiveness were assessed against recommended
commercially available Australian strains. The test legumes wereMacroptilium atropurpureum Urb. cv. Siratro,Vigna unguiculata (L.) Walp. cv Eureka,Centrosema pubescens Benth cv. Belalto andDesmodium heterocarpon (L) DC.
A significant portion of the native rhizobial isolates were of the fast growing type. Dry matter and total nitrogen production
forM. atropurpureum andV. unguiculata was highest when inoculated with native strains while the commerical strains produced superior dry matter production forC. pubescens andD. heterocarpon. However the total nitrogen production of native and commercial strains was not significantly different for the latter two
legumes.
The study indicated that a potential exists for developing inocula from local Rhizobium strains. 相似文献
10.
Yoshiko Kubota Akihiro Shima 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1991,160(6):621-625
Summary By using inbred strains (HO4C and HB32C) of the medaka,Oryzias latipes, the involvement of genetic factor(s) in the determination of thermoresistance of fish was investigated. The thermoresistance of embryos of the medaka was quantitated by the fraction of the embryos surviving 1 day after heat treatment. At early stages of development (st. 13 and st. 20–21), the HO4C strain was more resistant than the HB32C strain. At st. 20–21, the HO4C strain was more resistant than the HB32C strain at all temperatures used (42, 43, and 44°C). At later stages of development (st. 27 and st. 32), however, the HB32C strain was more resistant than the HO4C strain.The results of genetic cross experiments raised the following possibilities; the thermoresistance of embryos at early developmental stages can be lowered by some factor(s) inherited in the HO4C strain and/or increased by those in the HB32C strain. By contrast, the sensitivity of embryos at later stages of development was not affected by factor(s) of their parents, but by their own genetic constitution. 相似文献