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991.
992.
Laurence Culot Fernando Julio João Muñoz Lazo Marie-Claude Huynen Pascal Poncin Eckhard W. Heymann 《International journal of primatology》2010,31(4):553-569
Reduced dispersal of large seeds into degraded areas is one of the major factors limiting rain forest regeneration, as many
seed dispersers capable of transporting large seeds avoid these sites with a limited forest cover. However, the small size
of tamarins allows them to use small trees, and hence to disperse seeds into young secondary forests. Seasonal variations
in diet and home range use might modify their contribution to forest regeneration through an impact on the seed rain. For
a 2-yr period, we followed a mixed-species group of tamarins in Peru to determine how their role as seed dispersers in a 9-yr-old
secondary-growth forest varied across seasons. These tamarins dispersed small to large seeds of 166 tree species, 63 of which
were into a degraded area. Tamarins’ efficiency in dispersing seeds from primary to secondary forest varied across seasons.
During the late wet season, high dietary diversity and long forays in secondary forest allowed them to disperse large seeds
involved in later stages of regeneration. This occurred precisely when tamarins spent a more equal amount of time eating a
high diversity of fruit species in primary forest and pioneer species in secondary forest. We hypothesized that well-balanced
fruit availability induced the movement of seed dispersers between these 2 habitats. The noteworthy number of large-seeded
plant species dispersed by such small primates suggests that tamarins play an important, but previously neglected, role in
the regeneration and maintenance of forest structure. 相似文献
993.
Membrane transporters constitute one of the largest functional categories of proteins in all organisms. In the yeast Saccharomyces cerevisiae, this represents about 300 proteins (∼ 5% of the proteome). We here present the Yeast Transport Protein database (YTPdb), a user-friendly collaborative resource dedicated to the precise classification and annotation of yeast transporters. YTPdb exploits an evolution of the MediaWiki web engine used for popular collaborative databases like Wikipedia, allowing every registered user to edit the data in a user-friendly manner. Proteins in YTPdb are classified on the basis of functional criteria such as subcellular location or their substrate compounds. These classifications are hierarchical, allowing queries to be performed at various levels, from highly specific (e.g. ammonium as a substrate or the vacuole as a location) to broader (e.g. cation as a substrate or inner membranes as location). Other resources accessible for each transporter via YTPdb include post-translational modifications, Km values, a permanently updated bibliography, and a hierarchical classification into families. The YTPdb concept can be extrapolated to other organisms and could even be applied for other functional categories of proteins. YTPdb is accessible at http://homes.esat.kuleuven.be/ytpdb/. 相似文献
994.
Tensin2 reduces intracellular phosphatidylinositol 3,4,5-trisphosphate levels at the plasma membrane
Sassan Hafizi Anna Gustafsson Cecilia Oslakovic Anders Tengholm Bruno O. Villoutreix 《Biochemical and biophysical research communications》2010,399(3):396-1844
Tensins are proposed cytoskeleton-regulating proteins. However, Tensin2 additionally inhibits Akt signalling and cell survival. Structural modelling of the Tensin2 phosphatase (PTPase) domain revealed an active site-like pocket receptive towards phosphoinositides. Tensin2-expressing HEK293 cells displayed negligible levels of plasma membrane phosphatidylinositol 3,4,5-trisphosphate (PtdIns(3,4,5)P3) under confocal microscopy. However, mock-transfected cells, and Tensin2 cells harbouring a putative phosphatase-inactivating mutation, exhibited significant PtdIns(3,4,5)P3 levels, which decreased upon phosphatidylinositol 3-kinase inhibition with LY294002. In contrast, wtTensin3, mock and mutant cells were identical in membrane PtdIns(3,4,5)P3 and Akt phosphorylation. In vitro lipid PTPase activity was however undetectable in isolated recombinant PTPase domains of both Tensins, indicating a possible loss of structural stability when expressed in isolation. In summary, we provide evidence that Tensin2, in addition to regulating cytoskeletal dynamics, influences phosphoinositide-Akt signalling through its PTPase domain. 相似文献
995.
996.
Marco A. Coelho João M. F. Almeida Inês M. Martins A. Jorge da Silva José Paulo Sampaio 《Antonie van Leeuwenhoek》2010,98(3):331-342
Yeasts are common inhabitants of different types of aquatic habitats, including marine and estuarine waters and rivers. Although
numerous studies have surveyed yeast occurrence in these habitats, the identification of autochthonous populations has been
problematic because several yeast species seem to be very versatile and therefore mere presence is not sufficient to establish
an ecological association. In the present study we investigated the dynamics of the yeast community in the Tagus river estuary
(Portugal) by combining a microbiological study involving isolation, quantification, and molecular identification of dominant
yeast populations with the analysis of hydrological and hydrographical data. We set out to test the hypothesis of the multiple
origins of estuarine yeast populations in a transect of the Tagus estuary and we postulate four possible sources: open sea,
terrestrial, gastrointestinal and the estuary itself in the case of populations that have become resident. Candida parapsilosis and Pichia guilliermondii were correlated with Escherichia coli, which indicated an intestinal origin. Other cream-colored yeasts like Debaryomyces hansenii and Candida zeylanoides had similar dynamics, but no association with E. coli and quite distinct ecological preferences. They might represent a group of resident estuarine populations whose primary origin
is diverse and can include marine, terrestrial, and gastrointestinal habitats. Another major yeast population was represented
by Rhodotorula mucilaginosa. The cosmopolitan nature of that species and its moderate association with E. coli point to terrestrial sources as primary habitats. 相似文献
997.
998.
Oliveira AL Levada PM Zanotti-Magalhaes EM Magalhães LA Ribeiro-Paes JT 《Genetics and molecular research : GMR》2010,9(4):2436-2445
The relationships between schistosomiasis and its intermediate host, mollusks of the genus Biomphalaria, have been a concern for decades. It is known that the vector mollusk shows different susceptibility against parasite infection, whose occurrence depends on the interaction between the forms of trematode larvae and the host defense cells. These cells are called amebocytes or hemocytes and are responsible for the recognition of foreign bodies and for phagocytosis and cytotoxic reactions. The defense cells mediate the modulation of the resistant and susceptible phenotypes of the mollusk. Two main types of hemocytes are found in the Biomphalaria hemolymph: the granulocytes and the hyalinocytes. We studied the variation in the number (kinetics) of hemocytes for 24 h after exposing the parasite to genetically selected and non-selected strains of Biomphalaria tenagophila, susceptible or not to infection by Schistosoma mansoni. The differences were analyzed referred to the variations in the number of hemocytes in mollusks susceptible or not to infection by S. mansoni. The hemolymph of the selected and non-selected snails was collected, and hemocytes were counted using a Neubauer chamber at six designated periods: 0 h (control, non-exposed individuals), 2 h, 6 h, 12 h, 18 h and, 24 h after parasite exposure. Samples of hemolymph of five selected mollusks and five non-selected mollusks were separately used at each counting time. There was a significant variation in the number of hemocytes between the strains, which indicates that defense cells have different behaviors in resistant and susceptible mollusks. 相似文献
999.
Stolf-Moreira R Medri ME Neumaier N Lemos NG Pimenta JA Tobita S Brogin RL Marcelino-Guimarães FC Oliveira MC Farias JR Abdelnoor RV Nepomuceno AL 《Genetics and molecular research : GMR》2010,9(4):1946-1956
Soybean genotypes MG/BR46 (Conquista) and BR16, drought-tolerant and -sensitive, respectively, were compared in terms of morphophysiological and gene-expression responses to water stress during two stages of development. Gene-expression analysis showed differential responses in Gmdreb1a and Gmpip1b mRNA expression within 30 days of water-deficit initiation in MG/BR46 (Conquista) plants. Within 45 days of initiating stress, Gmp5cs and Gmpip1b had relatively higher expression. Initially, BR16 showed increased expression only for Gmdreb1a, and later (45 days) for Gmp5cs, Gmdefensin and Gmpip1b. Only BR16 presented down-regulated expression of genes, such as Gmp5cs and Gmpip1b, 30 days after the onset of moisture stress, and Gmgols after 45 days of stress. The faster perception of water stress in MG/BR46 (Conquista) and the better maintenance of up-regulated gene expression than in the sensitive BR16 genotype imply mechanisms by which the former is better adapted to tolerate moisture deficiency. 相似文献
1000.
Fabrizio Grandi Marcia M Colodel Lidianne N Monteiro João Rafael VP Leão Noeme S Rocha 《BMC veterinary research》2010,6(1):45