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71.
A 91-year record of seasonal and interannual variability of diatoms from laminated sediments in Saanich Inlet, British Columbia 总被引:1,自引:0,他引:1
Diatom seasonal succession and interannual variability werestudied using laminated sediments from Saanich Inlet, BritishColumbia, for the years 19001991. Frozen sediment coresallowed fine-scale sampling of laminae for each year. Thus,three seasons for each year were identified basedon species composition. Thalassiosira species were indicatorsof spring deposition. Skeletonema costatum was abundant in samplesfollowing Thalassiosira, probably deposited in late spring andsummer. Rhizosolenia sp. was most abundant in fall/winter samples.Diatom stratigraphies were related to sea surface temperature,salinity, sea level and the Pacific North American Index (PNA)using canonical correspondence analysis (CCA). CCA showed thatspecies of a particular season generally had optima for temperatureand salinity characteristic of that time. Interannual changesin diatom species composition and abundance were most prevalentin the decades 19201940, with the exception of S.costatumwhich showed cyclic changes in abundance. Skeletonema was moreabundant during periods of cool temperatures, while littoraldiatoms were more abundant during times of heavy winter rains.Sea level was an important variable in CCA and while its relationshipto diatoms is not clear, it may be related to variations innutrient supply to diatoms in surface waters. 相似文献
72.
Charles J. O'Kelly Michael E. Sieracki Edward C. Thier Ilana C. Hobson 《Journal of phycology》2003,39(5):850-854
The smallest known eukaryote, Ostreococcus tauri Courties et Chrétiennot-Dinet, was first reported as the dominant picoplankter in a French lagoon known for its diverse phytoplankton community and high oyster productivity. Long-term seasonal blooms of this picoeukaryote were observed in association with stable plankton communities. On 5 June 2001, a distinctive monotypic picoplankton bloom was detected by flow cytometry as part of an ongoing study of "brown tide" ( Aureococcus anophagefferens ) bloom initiation in Long Island bays. The bloom reached a concentration of 5 × 105 cells·mL−1 in West Neck Bay and lasted less than 2 weeks. Epifluorescence microscopy and TEM indicated that the bloom organism was an Ostreococcus -like picoalga, the first ever observed in a Long Island bay. Many cells of this alga contained numerous virus-like particles. The Ostreococcus -like picoalga, which resembles O. tauri , was rare in samples collected the following week. Instead, a substantial increase in the Synechococcus population was observed. Such rapid population changes have not previously been reported for Ostreococcus . Viral lysis and grazing by heterotrophic nanoflagellates may have contributed to the rapid decline of the Ostreococcus -like cells in West Neck Bay. 相似文献
73.
David A Winter Arthur O Quanbury Douglas A Hobson H.Grant Sidwall Gary Reimer Brian G Trenholm Thomas Steinke Henry Shlosser 《Journal of biomechanics》1974,7(6):479-486
A T.V.-computer system for the measurement and analysis of the kinematics of normal and abnormal locomotion has been developed which has the following characteristics: minimum encumberment to the subject or patient, determination of absolute coordinates of anatomical landmarks, analysis of 3 or 4 strides, and automation of data conversion and analysis. Analysis techniques have been developed which take advantage of the accuracy of the marker coordinates, and with suitable application of noise reduction filtering, permit direct calculation of velocities and accelerations (both linear and angular). Examples of some of these derived parameters vs time are presented. The results of a statistical study on a group of normal subjects walking at slow, comfortable and fast cadences yield the ranges of many velocities and accelerations not previously available. 相似文献
74.
Relationship between bacteria and ciliate protozoa in the sheep rumen 总被引:14,自引:0,他引:14
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Flyway population delineation in Taiga Bean Geese Anser fabalis fabalis revealed by multi‐element feather stable isotope analysis
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Anthony D. Fox Keith A. Hobson Adriaan de Jong Kevin J. Kardynal Geoff Koehler Thomas Heinicke 《Ibis》2017,159(1):66-75
Fundamental to effective management of migratory waterbird populations is an understanding of their flyway delineation. Taiga Bean Geese Anser fabalis fabalis wintering in NW Denmark, Scotland and England are considered to originate from northern and central Sweden, southern and central Norway (‘Western flyway’), those wintering in southern Sweden, NE and southern Denmark are considered to originate from northern Fennoscandia and western Russia (‘Central flyway’), and those wintering in eastern Germany and Poland (which show far less favourable conservation status) are thought to come from western Siberia (‘Eastern 1 flyway’), although evidence to demonstrate this has largely been lacking. Evidence for different natal and moult origins of Taiga Bean Geese was investigated using stable isotope analyses of feathers of four elements (δ2H, δ13C, δ15N and δ34S). There were significant differences in isotopic composition of feathers from Swedish (Central) and German (Eastern 1) wintering populations and those moulting in Sweden in late summer (Western), which validated the three proposed major management flyway units above. The strong continental gradient in the stable hydrogen isotope ratios in precipitation (δ2Hp) across the region was used to assign wintering birds geospatially to natal and moulting origin, indicating separate natal and moulting areas for German (n = 37, from western Siberia) and Swedish (n = 20, Fennoscandia and more western Russia) wintering birds. These results confirm the largely discrete nature of these three flyways and contribute significantly to our ability to deliver effective targeted and appropriate research, monitoring and management actions throughout the ranges of these flyways. 相似文献
79.
Karagiannis P Singer J Hunt J Gan SK Rudman SM Mechtcheriakova D Knittelfelder R Daniels TR Hobson PS Beavil AJ Spicer J Nestle FO Penichet ML Gould HJ Jensen-Jarolim E Karagiannis SN 《Cancer immunology, immunotherapy : CII》2009,58(6):915-930
Trastuzumab (Herceptin), a humanized IgG1 antibody raised against the human epidermal growth factor receptor 2 (HER2/neu), is the main antibody in clinical use against breast cancer. Pre-clinical evidence and clinical studies indicate that trastuzumab employs several anti-tumour mechanisms that most likely contribute to enhanced survival of patients with HER2/neu-positive breast carcinomas. New strategies are aimed at improving antibody-based therapeutics like trastuzumab, e.g. by enhancing antibody-mediated effector function mechanisms. Based on our previous findings that a chimaeric ovarian tumour antigen-specific IgE antibody showed greater efficacy in tumour cell killing, compared to the corresponding IgG1 antibody, we have produced an IgE homologue of trastuzumab. Trastuzumab IgE was engineered with the same light- and heavy-chain variable-regions as trastuzumab, but with an epsilon in place of the gamma-1 heavy-chain constant region. We describe the physical characterisation and ligand binding properties of the trastuzumab IgE and elucidate its potential anti-tumour activities in functional assays. Both trastuzumab and trastuzumab IgE can activate monocytic cells to kill tumour cells, but they operate by different mechanisms: trastuzumab functions in antibody-dependent cell-mediated phagocytosis (ADCP), whereas trastuzumab IgE functions in antibody-dependent cell-mediated cytotoxicity (ADCC). Trastuzumab IgE, incubated with mast cells and HER2/neu-expressing tumour cells, triggers mast cell degranulation, recruiting against cancer cells a potent immune response, characteristic of allergic reactions. Finally, in viability assays both antibodies mediate comparable levels of tumour cell growth arrest. These functional characteristics of trastuzumab IgE, some distinct from those of trastuzumab, indicate its potential to complement or improve upon the existing clinical benefits of trastuzumab. 相似文献
80.
Using stable-isotope analysis of feathers to distinguish moulting and breeding origins of seabirds 总被引:1,自引:0,他引:1
To determine whether stable isotope measurements of bird feathers can be used to identify moulting (interbreeding) foraging
areas of adult seabirds, we examined the stable-carbon (δ13C) and nitrogen (δ15N) isotopic composition of feathers of chicks and adults of black-browed albatrosses (Diomedea melanophrys) from Kerguelen Islands, southern Indian Ocean. Albatross chicks are fed primarily fish (75% by mass), the diet being dominated
by various species of the family Nototheniidae and Channichthyidae which commonly occur in the shelf waters in the vicinity
of the colony. δ13C and δ15N values in chick feathers, which are grown in summer in the breeding area, were lower than values in adult feathers, which
are grown in winter (δ13C: –19.6‰ versus –17.6‰ and δ15N: 12.4‰ versus 15.7‰, respectively). No differences in δ13C and δ15N values were found in adult wing feathers moulted in 1993 and 1994 and in adult feathers formed at the beginning, middle
and end of the 1994 moulting period. These data are consistent with adults moulting in the same area and feeding at the same
trophic level from one year to the next and with no major changes in foraging ecology within a given moulting season; they
suggest that foraging grounds were different in summer and winter and that these differed in their stable-isotope signature.
Changes in both feather δ13C and δ15N values indicated feeding south of the Subtropical Front (STF) during chick rearing, which is in agreement with the known
foraging ecology at this time and feeding north of the STF during moult. This, together with band recoveries from adult birds,
indicates that black-browed albatrosses from Kerguelen Islands wintered in subtropical waters off southern Australia. The
stable-isotope markers in feathers, therefore, have the potential for locating moulting areas of migratory seabird species
moving between isotopically distinct regions and for investigating seabirds’ foraging ecology during the poorly known interbreeding
period. Such information is needed for studies of year-round ecology of seabirds as well as for their conservation and the
long-term monitoring of the pelagic environment.
Received: 28 June 1999 / Accepted: 14 September 1999 相似文献