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741.
We studied diet selection of the globally threatened lesser white-fronted goose Anser eythropus at a spring staging area on the island of Hailuoto (64°00'N, 24°45'E), off the western coast of Finland. We determined the diet using droppings, which were collected in late May, when the geese had left the area and migrated northwards. The sample potentially comprised of ejecta from 31 different individuals. Plant idengification was based on visual determination of epidermal fragments. A total of 100 droppings were sampled using a point quadrat method. We calculated the percentage of each idengified taxon in each dropping and related this to the availability of the corresponding taxon in the meadow. We measured preference for each taxon using Chesson's electivity index (ɛi ) and tested them by bootstrap resampling. The diet contained 9 taxa of the ca 40 available. Almost all dietary items were Monocotyledons (99.9%), mostly grasses (88.7%) including Festuca rubra (43%), Phragmites australis (30%) and Calamagrostis stricta (13%). Only Phragmites (ɛ=0.73, p=0.000), Festuca (ɛ=0.52, p=0.004) and possibly Triglochin palustris (ɛ=0.70, p=0.125) were preferred, all other species were avoided. All preferred species were quite common and other goose species exploit them too. The lesser white-fronted geese preferred large natural meadows that were five times broader than an "average" Bothnian Bay meadow. All forms of mowing and grazing management benefit the restoration of lesser white-fronted goose habitats at the landscape level. Festuca and especially Triglochin benefit from such management. Reeds, Phragmites , whose spread has been the main cause of coastal meadow deterioration, can be controlled by management, but can also be maintained among other vegetation if mowing is less frequent or grazing not too intensive. 相似文献
742.
Fominka Nestor T. Oliveira Hernani F. M. Taboue Geraud C. Tasse Luma Francis E. Robinson Carolyn A. Fokam Eric B. 《Primates; journal of primatology》2021,62(3):537-546
Primates - The growing dependence of villagers on local forests (food, wood, etc.) makes the comparative assessment of the perceptions they have of the forest and its wildlife increasingly... 相似文献
743.
José Manuel Borrero-de Acuña Izabook Gutierrez-Urrutia Cristian Hidalgo-Dumont Carla Aravena-Carrasco Matias Orellana-Saez Nestor Palominos-Gonzalez Jozef B. J. H. van Duuren Viktoria Wagner Lars Gläser Judith Becker Michael Kohlstedt Flavia C. Zacconi Christoph Wittmann Ignacio Poblete-Castro 《Microbial biotechnology》2021,14(6):2385-2402
Lignin-based aromatics are attractive raw materials to derive medium-chain length poly(3-hydroxyalkanoates) (mcl-PHAs), biodegradable polymers of commercial value. So far, this conversion has exclusively used the ortho-cleavage route of Pseudomonas putida KT2440, which results in the secretion of toxic intermediates and limited performance. Pseudomonas putida H exhibits the ortho- and the meta-cleavage pathways where the latter appears promising because it stoichiometrically yields higher levels of acetyl-CoA. Here, we created a double-mutant H-ΔcatAΔA2 that utilizes the meta route exclusively and synthesized 30% more PHA on benzoate than the parental strain but suffered from catechol accumulation. The single deletion of the catA2 gene in the H strain provoked a slight attenuation on the enzymatic capacity of the ortho route (25%) and activation of the meta route by nearly 8-fold, producing twice as much mcl-PHAs compared to the wild type. Inline, the mutant H-ΔcatA2 showed a 2-fold increase in the intracellular malonyl-CoA abundance – the main precursor for mcl-PHAs synthesis. As inferred from flux simulation and enzyme activity assays, the superior performance of H-ΔcatA2 benefited from reduced flux through the TCA cycle and malic enzyme and diminished by-product formation. In a benzoate-based fed-batch, P. putida H-ΔcatA2 achieved a PHA titre of 6.1 g l–1 and a volumetric productivity of 1.8 g l–1 day–1. Using Kraft lignin hydrolysate as feedstock, the engineered strain formed 1.4 g l- 1 PHA. The balancing of carbon flux between the parallel catechol-degrading routes emerges as an important strategy to prevent intermediate accumulation and elevate mcl-PHA production in P. putida H and, as shown here, sets the next level to derive this sustainable biopolymer from lignin hydrolysates and aromatics. 相似文献
744.
Ryan Keenan Cañete-Gibas Connie Sanders Carmita Sosa Nestor Wiederhold Nathan P. 《Mycopathologia》2021,186(3):441-447
Mycopathologia - This report describes the phenotypic characteristics of a novel fungal species, isolated from a prosthetic hip infection. The patient, who had undergone multiple total hip... 相似文献
745.
746.
Identification and quantification of subsets of mononuclear inflammatory cells in melanocytic and other human tumors 总被引:1,自引:0,他引:1
M S Nestor A J Cochran 《Pigment cell research / sponsored by the European Society for Pigment Cell Research and the International Pigment Cell Society》1987,1(1):22-27
We used monoclonal antibodies and an indirect immunoperoxidase technique to identify mononuclear inflammatory cells associated with human tumors. The absolute number of the different types of inflammatory cells was assessed by using a point-counting technique. We studied tissues from six primary cutaneous melanomas, six metastatic melanomas, eight melanocytic nevi, 14 breast cancers, seven examples of fibrocystic disease of the breast, 11 lung cancers, and six colon cancers. Virtually all tumors were associated with substantial numbers of T lymphocytes (Leu3a-positive T helper-inducer cells predominating) and macrophages. Primary melanomas contained significantly more T lymphocytes (P less than .002), macrophages (P less than .005), and Langerhans/dendritic cells (P less than .002) than nevi or normal skin and had a higher proportion of T cells than metastatic melanomas (P less than .01). Breast cancers contained more T lymphocytes and macrophages than occur with fibrocystic disease (P less than .0001 and P less than .002, respectively) and more B lymphocytes. Cancers of the lung and colon contained moderate numbers of T lymphocytes and macrophages; however, colon cancers contained a higher proportion of B cells. Leu7-positive NK/K cells were noted in small numbers in all tumors examined. 相似文献
747.
748.
Benjamin Klempay Nestor Arandia-Gorostidi Anne E. Dekas Douglas H. Bartlett Christopher E. Carr Peter T. Doran Avishek Dutta Natalia Erazo Luke A. Fisher Jennifer B. Glass Alexandra Pontefract Sanjoy M. Som Jesse M. Wilson Britney E. Schmidt Jeff S. Bowman 《Environmental microbiology》2021,23(7):3825-3839
Concurrent osmotic and chaotropic stress make MgCl2-rich brines extremely inhospitable environments. Understanding the limits of life in these brines is essential to the search for extraterrestrial life on contemporary and relict ocean worlds, like Mars, which could host similar environments. We sequenced environmental 16S rRNA genes and quantified microbial activity across a broad range of salinity and chaotropicity at a Mars-analogue salt harvesting facility in Southern California, where seawater is evaporated in a series of ponds ranging from kosmotropic NaCl brines to highly chaotropic MgCl2 brines. Within NaCl brines, we observed a proliferation of specialized halophilic Euryarchaeota, which corresponded closely with the dominant taxa found in salterns around the world. These communities were characterized by very slow growth rates and high biomass accumulation. As salinity and chaotropicity increased, we found that the MgCl2-rich brines eventually exceeded the limits of microbial activity. We found evidence that exogenous genetic material is preserved in these chaotropic brines, producing an unexpected increase in diversity in the presumably sterile MgCl2-saturated brines. Because of their high potential for biomarker preservation, chaotropic brines could therefore serve as repositories of genetic biomarkers from nearby environments (both on Earth and beyond) making them prime targets for future life-detection missions. 相似文献
749.
Myostatin maps to the interval containing the bovine mh locus 总被引:1,自引:0,他引:1
Timothy P.L. Smith Nestor L. Lopez-Corrales Steven M. Kappes Tad S. Sonstegard 《Mammalian genome》1997,8(10):742-744
Myostatin (GDF-8) is a member of the transforming growth factor-β superfamily and plays a role in muscle growth and development.
Mice having targeted disruption of this gene display marked increases in muscle mass, a phenotype similar to the muscular
hypertrophy (mh) in several cattle breeds. Physical mapping data developed from YAC clones indicate the bovine myostatin gene lies close
to the centromere of bovine Chromosome (Chr) 2 (BTA2) at 2q11, indistinguishable from the cytogenetic location of the mh locus. In addition, a polymorphism in the second intron of the gene was used to show that myostatin maps within the interval
previously shown to contain mh. These data suggest myostatin may be the gene causing muscular hypertrophy in cattle.
Received: 19 June 1997 / Accepted: 2 July 1997 相似文献