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101.
Plant cell vacuoles may have storage or lytic functions, but biochemical markers specific for the tonoplasts of functionally distinct vacuoles are poorly defined. Here, we use antipeptide antibodies specific for the tonoplast intrinsic proteins alpha-TIP, gamma-TIP, and delta-TIP in confocal immunofluorescence experiments to test the hypothesis that different TIP isoforms may define different vacuole functions. Organelles labeled with these antibodies were also labeled with antipyrophosphatase antibodies, demonstrating that regardless of their size, they had the expected characteristics of vacuoles. Our results demonstrate that the storage vacuole tonoplast contains delta-TIP, protein storage vacuoles containing seed-type storage proteins are marked by alpha- and delta- or alpha- and delta- plus gamma-TIP, whereas vacuoles storing vegetative storage proteins and pigments are marked by delta-TIP alone or delta- plus gamma-TIP. In contrast, those marked by gamma-TIP alone have characteristics of lytic vacuoles, and results from other researchers indicate that alpha-TIP alone is a marker for autophagic vacuoles. In root tips, relatively undifferentiated cells that contain vacuoles labeled separately for each of the three TIPs have been identified. These results argue that plant cells have the ability to generate and maintain three separate vacuole organelles, with each being marked by a different TIP, and that the functional diversity of the vacuolar system may be generated from different combinations of the three basic types. 相似文献
102.
Zebra mussel (Dreissena polymorpha) seasonal colonization patterns, growth and habitat preferences were determined in a sub-tropical
floodplain river at the southern edge of its distribution in North America during 1995–96 (Atchafalaya River Basin, Louisiana).
Zebra mussel movement into subtropical areas represents a major frontier for this species worldwide. The onset of adult zebra
mussel colonies occurred when the minimum daily temperature dropped below 31 °C and dissolved oxygen levels rose above 6.5
mg l-1 in the fall. By mid-winter, mussel populations were established at lateral distances >10 km from the main river channel.
Mussel growth occurred throughout the winter with an increase in growth in April and May. Adult mortality occurred during
May–August as dissolved oxygen levels declined and minimum daily temperature warmed above 29 °C in the floodplain and 32.5
°C in riverine sites. Limiting factors responsible for the seasonal pattern include temperature and dissolved oxygen tolerances
experienced during summer months in the ARB. Summer water conditions apparently preclude establishment of resident zebra mussel
populations in the Atchafalaya floodplain. Naturally occurring seasonal patterns in temperature and dissolved oxygen in floodplain
rivers may have implications for the expansion of this exotic mollusk in warmwater systems with source colonies restricted
to mainstem rivers and seasonal sinks in floodplain regions.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
103.
Retinoids are known to induce the differentiation and cell cycle arrest of human myeloid leukemia cells in vitro. Differential display was used to identify putative early regulatory genes that are differentially expressed in HL-60 human promyelocytic leukemia cells treated with retinoic acid. One of the cDNAs cloned encodes sequences identifying Burkitt's lymphoma receptor 1 (BLR1), a recently described chemokine receptor. Northern blot analysis demonstrates that blr1 mRNA expression increases within 9 h of retinoic acid treatment, well before functional differentiation or G1/G0 growth arrest at 48 h or onset of morphological changes, suggesting a possible regulatory function. The expression of blr1 mRNA is transient, peaking at 72 h when cells are differentiated. blr1 mRNA also is induced by other differentiation-inducing agents, 1α,25-dihydroxyvitamin D3 and DMSO. Induction of blr1 mRNA by retinoic acid is not blocked by the protein synthesis inhibitor cycloheximide. In HL-60 cells stably transfected with blr1 cDNA, ectopic expression of blr1 causes an increase in ERK2 MAPK activation and promotes retinoic acid-induced G1/G0 growth arrest and cell differentiation. The early expression of blr1 mRNA during differentiation, its ability to increase ERK2 activation, and its enhancement of retinoic acid-induced differentiation suggest that blr1 expression may be involved in retinoic acid-induced HL-60 differentiation. 相似文献
104.
Male inflorescences, female inflorescences, and leaves collected from dormant buds of three sweetgum (Liquidambar styraciflua) trees were tested for induction of somatic embryogenesis following treatment with thidiazuron, naphthaleneacetic acid (NAA)
or different combinations of the two. Explants were placed into culture either within a few days after collection or following
2 months of storage at –15 °C. Although embryogenic cultures were obtained from all three trees, embryogenesis induction
was strongly affected by genotype (source tree), with 100% of the staminate inflorescence explants from one tree producing
embryogenic cultures in one experiment. Embryogenesis induction was also influenced by explant type, with staminate inflorescences
up to five times more likely to produce an embryogenic culture than female inflorescences. No embryogenic cultures were obtained
from leaf explants. While treatment with plant growth regulators was not required for embryogenesis induction from inflorescence
explants, culture on medium with NAA alone resulted in the highest production of repetitively embryogenic cultures and cultures
producing proembryogenic masses. Dormant buds stored for 2 months at –15 °C were still able to produce embryogenic cultures,
although frozen storage decreased this ability by over one-half for staminate inflorescences.
Received: 20 January 1999 / Revision received: 18 April 1999 / Accepted: 29 April 1999 相似文献
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109.
CHING‐TE CHIEN SHUN‐YING CHEN JERRY M. BASKIN CAROL C. BASKIN 《Plant Species Biology》2011,26(1):99-104
We determined the kind of seed dormancy in Schisandra arisanensis, an ANA grade ([A]mborellales [N]ymphaeales [A]ustrobaileyales) angiosperm with medicinal value. Seeds have small underdeveloped embryos, and following seed maturity their length increased approximately 360% before radicle emergence. Germination was delayed 6–8 weeks, and the percentage and rate were much higher at 15/6, 20/10 and 25/15°C than at 30/20°C. For seeds incubated at 5/5°C (8 weeks) → 15/6°C (4 weeks) → 20/10°C (8 weeks) → 25/15°C (12 weeks) → 20/10°C (5 weeks), embryos grew at 15/6°C → 20/10°C, and almost all seeds that germinated (89%) did so at 20/10°C → 25/15°C. When seeds were incubated in a complementary temperature sequence, 25/15°C (12 weeks) → 20/10°C (8 weeks) → 15/6°C (4 weeks) → 5/5°C (9 weeks) → 15/6°C (4 weeks), embryos grew at 25/15°C → 20/10°C. Nearly all seeds that germinated (93%) did so at 25/15°C → 20/10°C and at 15/6°C following 9 weeks at 5/5°C. Based on the temperature requirements for embryo growth and seed germination, seeds of this species have non‐deep simple morphophysiological dormancy (C1bB). 相似文献
110.
William H. Battle 《BMJ (Clinical research ed.)》1905,1(2301):277-278