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941.
Narasaraju T Sim MK Ng HH Phoon MC Shanker N Lal SK Chow VT 《Microbes and infection / Institut Pasteur》2009,11(1):2-11
Most pandemic influenza virus strains undergo adaptation or reassortment before they acquire the ability to cause fatal infections in a new host species. The pathologic changes and tissue tropism during virus adaptation are not fully understood. Here we investigated pathologic changes and tissue tropism by serial lung-to-lung passaging of human influenza virus strain A/Aichi/2/68 (H3N2) in a BALB/c mouse model. Enhanced pulmonary lesions and systemic virus infection were observed during adaptation. Late passage 10 (P10) virus caused extra-pulmonary spread with necrotic and inflammatory lesions in the brain, heart, spleen and intestine of infected animals, in contrast to infection with earlier passage viruses which were restricted to lungs. Non-conservative mutations in the hemagglutinin (Gly218Glu) and non-structural 1 (Asp125Gly) proteins were identified in P10 virus which exhibited high virulence. Virus growth kinetics showed enhanced replication ability of P10 virus in different cell lines. P10 virus also exhibited the ability to bind to erythrocytes of different host species. These results demonstrate extra-pulmonary spread of influenza virus during adaptation with enhanced replication ability in a new host. This mouse adaptation model may provide a basis for understanding cross-species adaptability corresponding to increased virulence of the influenza A virus, a phenomenon of relevance to the emergence of future highly pathogenic strains. 相似文献
942.
Aki Kato Silvia M. P. B. Guimarães Hiroshi Kawai Michio Masuda 《Phycological Research》2009,57(1):74-86
The vegetative and reproductive morphology of the crustose red alga Peyssonnelia japonica (Segawa) Yoneshigue was re‐examined based on the holotype specimen and recent collections from various localities in Japan, including the type locality, and Hawaii. This species is characterized by the following features: thallus with appressed margins, perithallial filaments arising from the entire upper surface of each hypothallial cell (the Peyssonnelia rubra‐type), easily separable perithallial filaments in a gelatinous matrix, hypothallial filaments arranged in parallel rows, unicellular rhizoids, hypobasal calcification, gonimoblasts derived mainly from connecting filaments, and spermatangia produced in a series of whorls comprised of one to four paired spermatangia surrounding each central cell (the Peyssonnelia dubyi‐type). In addition to these features, the dimensions of the vegetative and reproductive structures of Peyssonnelia boudouresquei Yoneshigue described from Brazil were consistent with those of P. japonica. Molecular phylogenetic analyses using partial 26S rDNA, rbcL, and cox2‐3 spacer DNA sequences also supported the monophyly of P. japonica (from 16 localities in Japan and one locality in Hawaii) and P. boudouresquei (from two localities in Brazil). Therefore, P. boudouresquei may be a taxonomic synonym of P. japonica. However, considering the relatively high sequence divergences between the two taxa (2.1–2.5% in partial 26S rDNA, 5.9–6.7% in rbcL, and 5.8–6.7% in cox2‐3 spacer), and the relatively limited geographic sampling ranges, we reserve the taxonomic conclusion until further morphological and genetic data of the specimens from other geographic areas connecting Japan and Brazil become available. 相似文献
943.
Although modern forestry takes into consideration the analysis of the effects of forest management on plant structure, diversity
and seedlings, little is known about how those parameters respond to harvest techniques in the Mediterranean region. We investigated
the effect of three different harvest intensities, respect to uncut controls, on understory plant species functional groups,
richness, diversity and pine seedlings in a natural Maritime pine stand in Spain, three years after harvesting. The harvest
treatments produced a reduction of the number of Pinus pinaster seedlings and woody species cover, and an increase of species richness (total and of annual species) and plant cover of annual
species respect to control plots (CO). The Shannon diversity values showed no differences between treatments. These results
emphasize that the tree harvest treatments analyzed are not suitable for the management of this P. pinaster stand. Otherwise, the reduction of pine seedling density by harvest treatments and the changes in richness and cover of functional
groups would not induce the natural regeneration of this stand maintaining the understory plant layer. 相似文献
944.
Adriana R. Silva Patricia Pacheco Adriana Vieira-de-Abreu Clarissa M. Maya-Monteiro Barbara D'Alegria Kelly G. Magalhães Edson F. de Assis Christianne Bandeira-Melo Hugo C. Castro-Faria-Neto Patricia T. Bozza 《Biochimica et Biophysica Acta (BBA)/Molecular and Cell Biology of Lipids》2009,1791(11):1066-1075
Lipid-laden foam macrophages are emerging as key players in early atherogenesis. Even though cytoplasmic lipid bodies (lipid droplets) are now recognized as organelles with cell functions beyond lipid storage, the mechanisms controlling lipid body biogenesis within macrophages and their additional functions in atherosclerosis are not completely elucidated. Here we studied oxLDL-elicited macrophage machinery involved in lipid body biogenesis as well as lipid body roles in leukotriene (LT) synthesis. Both in vivo and in vitro, oxLDL (but not native LDL) induced rapid assembly of cytoplasmic lipid bodies-bearing ADRP within mice macrophages. Such oxLDL-elicited foamy-like phenotype was a pertussis toxin-sensitive process that depended on a paracrine activity of endogenous MCP-1/CCL2 and activation of ERK. Pretreatment with neutralizing anti-MCP-1/CCL2 inhibited macrophage ADRP protein expression induced by oxLDL. By directly immuno-localizing leukotrienes at their sites of synthesis, we showed that oxLDL-induced newly formed lipid bodies function as active sites of LTB4 and LTC4 synthesis, since oxLDL-induced lipid bodies within foam macrophages compartmentalized the enzyme 5-lipoxygenase and five lipoxygenase-activating protein (FLAP) as well as newly formed LTB4 and LTC4. Consistent with MCP-1/CCL-2 role in ox-LDL-induced lipid body biogenesis, in CCR2 deficient mice both ox-LDL-induced lipid body assembly and LT release were reduced as compared to wild type mice. In conclusion, oxLDL-driven foam cells are enriched with leukotriene-synthesizing lipid bodies – specialized organelles whose biogenic process is mediated by MCP-1/CCL2-triggered CCR2 activation and ERK-dependent downstream signaling – that may amplify inflammatory mediator production in atherosclerosis. 相似文献
945.
Elizabeth Fullam Akane Kawamura Helen Wilkinson Areej Abuhammad Isaac Westwood Edith Sim 《The protein journal》2009,28(6):281-293
Arylamine N-acetyltansferase (NAT) from Mycobacterium tuberculosis (TBNAT) is a potential drug target for anti-tubercular therapy. Recombinant TBNAT is much less soluble and is produced in
lower yields than the closely related NAT from Mycobacterium marinum (MMNAT). In order to explore MMNAT as a model for TBNAT in drug discovery, we compare the two mycobacterial NAT enzymes.
Two site-directed mutants of MMNAT have been prepared and characterised: MMNAT71, Tyr → Phe and MMNAT209, Met → Thr, in which
residues within 6 Å of the active-site cysteine have been replaced with the corresponding residue from TBNAT. Two chimeric
proteins have also been produced in which the third domain of MMNAT has been replaced by the third domain of TBNAT and vice
versa. The activity profile of the chimeric proteins suggests a role for the third domain in the evolutionary divergence of
NAT between these closely related mycobacterial species. 相似文献
946.
Violeta Saló Rafel Simó Maria Vila‐Costa Albert Calbet 《Environmental microbiology》2009,11(12):3063-3072
A laboratory grazing experiment was conducted with the aim of quantifying the sulfur assimilation by a herbivore protist feeding on a dimethylsulfoniopropionate (DMSP)‐containing phytoplankter. When supplied with dissolved 35S‐DMSP, cultures of an axenic strain of the diatom Thalassiosira pseudonana took up 60–95% of the added radioisotope and accumulated it untransformed in the cytoplasm. Radiolabelled diatom cells were offered as prey to the heterotrophic dinoflagellate Oxyrrhis marina. After 32 h in the dark, all the prey had been grazed and digested, leaving only radiolabelled O. marina in the grazing bottles and thus providing an estimate of the percentage of DMSP‐sulfur retained by the predator. Subsequent precipitation with cold trichloroacetic acid (TCA) provided the fraction of retained DMSP‐S that had been assimilated into the micrograzer macromolecules. In parallel incubations with predator and dissolved 35S‐DMSP only (no prey), O. marina (and their closely associated bacteria) took up the radiolabelled substrate osmotrophically to an activity of 0.04 dpm cell?1 and assimilated it all into macromolecules. By correcting grazing 35S‐DMSP assimilation for osmotrophic 35S‐DMSP assimilation, and comparing it with the ingested radioisotope, the percentage of ingested DMSP‐sulfur retained and assimilated by the predator was determined to be 32 ± 4%. This is the first study that provides direct evidence that ingestion of a DMSP‐containing prey supplies structural sulfur to a herbivore protist and that quantifies this assimilative supply at one‐third of ingested DMSP. 相似文献
947.
Background
Members of the calcium-activated chloride channel (CLCA) gene family have been suggested to possess a variety of functions including cell adhesion and tumor suppression. Expression of CLCA family members has mostly been analyzed in non-neural tissues. Here we describe the expression of mouse and human CLCA genes in the nervous system. 相似文献948.
949.
Claudia Chaves Loureiro Marta Drummond Adriana Magalhães Elisabete SantaClara Miguel Gonçalves João Carlos Winck 《Journal of medical case reports》2009,3(1):1-7
Introduction
There seem to be no published data concerning the clinical impact of populations of hepatitis B virus (HBV) in the hepatic and extrahepatic compartments of HIV-infected people with severe acute hepatitis.Case presentation
A 26-year-old Caucasian man presenting to our hospital with clinical symptoms suggesting acute hepatitis was found to have an acute hepatitis B profile upon admission. He developed fatal fulminant hepatitis and was found to be heavily immunocompromised due to HIV-1 infection. He had a high plasma HBV and HIV load, and analysis of the partial pre-S1/pre-S2 domain showed the presence of mixed infection with D and F genotypes. Analysis of the point mutations within this region revealed the presence of HBV strains with amino acid substitutions at the immunodominant epitopes involved in B or T cell recognition. A homogeneous population of a pre-core mutant strain harbouring the A1896G and A1899G affecting HBeAg expression was invariably found in the liver tissue, plasma and peripheral blood mononuclear cells despite active HBeAg secretion; it was the dominant strain in the liver only, and was characterised by the presence of two point mutations in the direct repeat 1 domain involved in HBV replication activity. Taken together, these mutations are indicative of a highly replicative virus capable of evading immune responses.Conclusion
This case report provides clinical evidence of a possible association between the rapid spread of highly replicative escape mutants and the development of fulminant hepatitis in a heavily immunocompromised patient. Virological surveillance of severe acute hepatitis B may be important in establishing an early treatment strategy involving antiviral drugs capable of preventing liver failure, especially in individuals for whom liver transplantation is not accepted as a standard indication. 相似文献950.
Sung Eun Sim Yoon Hee Chung Ji Hoon Jeong Sin Weon Yun Hyoun-Sub Lim Daejin Kim Sung Su Kim Won Bok Lee Choong Ik Cha 《Journal of molecular histology》2009,40(2):157-163
In the present study, we performed immunohistochemical studies to investigate the changes of insulin-like growth factor binding
protein 2 (IGFBP2) in the central nervous system of SOD1G93A mutant transgenic mice as an in vivo model of amyotrophic lateral sclerosis (ALS). Decreased immunoreactivity for IGFBP2
was observed in the cerebral cortex, hippocampus and brainstem of SOD1G93A transgenic mice. In the cerebral cortex, the number of IGFBP2-positive cells was decreased in the somatomotor area, somatosensory
area, auditory area, visual area, entorhinal area, piriform area and prefrontal area. In the hippocampal formation, IGFBP2
immunoreactivity was significantly decreased in the CA1-3 areas and the dentate gyrus. In the brainstem, few IGFBP2-immunoreactive
cells were observed in the medullary and pontine reticular formation, vestibular nucleus, trigeminal motor nucleus, facial
nucleus, hypoglossal nucleus and raphe nucleus. In the spinal cord, IGFBP2 immunoreactivity was not significantly decreased
in SOD1G93A transgenic mice. This study showing decreased IGFBP2 in different brain regions of SOD1G93A transgenic mice may provide clues for understanding differential susceptibility of neural structures in ALS.
S. E. Sim and Y. H. Chung have contributed equally to this work. 相似文献