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51.
Delivery of DNA into mammalian cells by receptor-mediated endocytosis and gene therapy 总被引:8,自引:0,他引:8
The correction of genetically based disorders by the introduction of a therapeutic genetic construct into the appropriate
cell type (“gene therapy”), has become a distinct possibility in recent years. In order for gene therapy to be a practical
alternative to more conventional pharmaceutical approaches to treatment, it must be administrable in vivo. This demands that
a system be developed that can specifically target the DNA to the desired cell type once introduced into the patient. Among
the procedures that are currently being pursued, the delivery of DNA to cells by receptor mediated endocytosis (RME), comes
closest to fulfilling this crucial requirement.
The natural physiological process of RME can be exploited to deliver genetic material to cells. An antibody or ligand to a
cell surface receptor that is known to undergo endocytosis, is complexed with DNA through a covalently linked polycationic
adjunct (e.g., polylysine, protamines). Such complexes retain their binding specificity to the cell surface and are taken
up into the cell where they enter the endosomal compartment via normal endocytotic processes. In addition, steps must be taken
to avoid degradation of the DNA within the endosome-lysosome. Cells can be treated with the lysosomatropic agent chloroquine
during the transfection procedure. Alternatively, the components of viruses that enter cells by endocysis and possess an endosomal
“break out” capacity can be used. Replication defective adenovirus coupled to the ligand-DNA complex gives transfection efficiencies
of virtually 100% on tissue culture cells in vitro. Synthetic peptides that mimic the membrane fusing region of influenza
virus hemagglutinin, have also been successfully used as part of the ligand-DNA complex to bring about endosomal escape.
Preliminary studies have demonstrated the potential of this method to specifically target DNA to the cell type of choice in
vivo. Delivery of genes by receptor-mediated endocytosis offers the greatest hope that gene therapy can be an inexpensive,
easily applicable, widespread technology. 相似文献
52.
Comparative limnology,species diversity and biomass relationship of zooplankton and phytoplankton in five freshwater lakes in Kenya 总被引:4,自引:2,他引:2
Comparative studies on the limnology, species diversity and standing stock biomass of phytoplankton and zooplankton in five freshwater lakes, Naivasha and Oloidien, Ruiru, Masinga and Nairobi reservoirs, were undertaken. Phytoplankton chlorophyll a, dissolved oxygen and temperature were also measured. Thermocyclops oblongatus (Copepoda) was dominant in all the lakes. Ceriodaphnia cornuta and Diaphanosoma excisum (Cladocera) dominated in lakes Naivasha and Oloiden, whereas in Ruiru, Masinga and Nairobi reservoirs, Brachionus angularis and Hexarthra mira (Rotifera) were the dominant zooplankters. Phytoplankton biomass as chlorophyll a was lowest in Ruiru dam 5.64 ± 4.0 µg l-1 and highest in the eutrophic Nairobi dam 71.5 ± 12.02 µg l-1. The endorheic lakes Naivasha and Oloidien showed medium values of 24.5 ± 4.0 µg l-1. 相似文献
53.
54.
Neelam Shahab Kamarulzaman Kamaruddin Jacqueline Platt Philip R Butler Stephen G Oliver Glyn Hobbs 《Biotechnology letters》1994,16(10):1015-1020
Summary In order to examine the physiology ofStreptomyces coelicolor when growing on solid media, we have employed a membrane overlay technique and used a new approach to extract substrate and product compounds from the agar. Comparisons made with liquid grown cultures indicate a change from non-growth associated productivity of actinorhodin in liquid culture, to growth associated production on agar plates. In contrast, the temporal control of methylenomycin production was virtually identical under both culture conditions. Considerable extracellular protein production was observed during growth on agar. 相似文献
55.
Pascal Genschik Andrée Durr Jacqueline Fleck 《Molecular genetics and genomics : MGG》1994,244(5):548-556
We characterized three genes encoding different E2-type ubiquitin carrier proteins involved in the ubiquitin-mediated proteolytic pathway:UbcAt3 shows homologies to the yeastCDC34 gene andUbcAt4a andUbcAt4b are two different genes homologous to theUbc1/4/5 subfamily in yeast. Their accumulation was analysed and compared with that of the different families encoding polyubiquitins, as well as the monoubiquitin fusion protein, which is considered as a marker for cell division, during various developmental stages including GO/S transition and senescence of higher plant cells. Our results imply that theseUbc genes are under the control of complex mechanisms, and are differentially regulated, but not necessarily co-regulated with ubiquitin genes. Even the closely relatedUbcAt4a andUbcAt4b genes of the same multigene subfamily are controlled by distinct regulatory mechanisms. 相似文献
56.
57.
58.
Jacqueline L. Fernandez W. J. Simpson T. M. Dowhanick 《Letters in applied microbiology》1993,17(6):292-296
Of a range of media tested for enumeration of Obesumbacterium proteus in brewers' yeast, Universal Beer agar and Wallerstein Laboratories Differential medium were most effective. MacConkey agar (several types) and Membrane Lauryl Sulphate agar were least effective. Other media (Wort agar, YM agar) were of intermediate efficacy. Nine O. proteus strains from commercial yeast samples were characterized using the API 20E test kit, the Biolog GN microplate (BGNM) and by SDS-PAGE of their total soluble proteins. Both the BGNM and SDS-PAGE techniques allowed the strains to be differentiated from one another: the API 20E kit did not. All strains isolated from UK breweries belonged to O. proteus biogroup II. Four of these strains displayed a branching cell morphology not hitherto described in any member of the Enterobacteriaceae. 相似文献
59.
Daniel E. Gomez Jacqueline L. Hartzler Robert H. Corbitt Alexander M. Nason Unnur P. Thorgeirsson 《In vitro cellular & developmental biology. Animal》1993,29(6):451-455
Summary We describe a fast and reproducible method that can be used as a final step in obtaining pure populations of liver endothelial
cells. This method employs endothelial cell specific lectin covalently bound to magnetic polystyrene beads (Dynabeads). Evonymus
europaeus agglutinin (EEA)-coated Dynabeads were used to purify monkey liver endothelium from Percoll gradient separated nonparenchymal
cells. EEA-coated beads were also successfully used to purify monkey aortic endothelial cells. The endothelial cells grew
to confluence as a cobblestonelike monolayer, expressed Factor VIII related antigen, and incorporated acetylated-low density
lipoprotein. The magnetic beads seemed not to modify the normal properties of the isolated endothelium, thus facilitating
their use in experimental studies. This immunomagnetic separation technique may be applicable for purification of endothelial
cells from a wide variety of tissue sources. 相似文献
60.
Michael Vreones Maja Mustapic Ruin Moaddel Krishna A. Pucha Jacqueline Lovett Douglas R. Seals Dimitrios Kapogiannis Christopher R. Martens 《Aging cell》2023,22(1):e13754
Declining nicotinamide adenine dinucleotide (NAD+) concentration in the brain during aging contributes to metabolic and cellular dysfunction and is implicated in the pathogenesis of aging-associated neurological disorders. Experimental therapies aimed at boosting brain NAD+ levels normalize several neurodegenerative phenotypes in animal models, motivating their clinical translation. Dietary intake of NAD+ precursors, such as nicotinamide riboside (NR), is a safe and effective avenue for augmenting NAD+ levels in peripheral tissues in humans, yet evidence supporting their ability to raise NAD+ levels in the brain or engage neurodegenerative disease pathways is lacking. Here, we studied biomarkers in plasma extracellular vesicles enriched for neuronal origin (NEVs) from 22 healthy older adults who participated in a randomized, placebo-controlled crossover trial (NCT02921659) of oral NR supplementation (500 mg, 2x /day, 6 weeks). We demonstrate that oral NR supplementation increases NAD+ levels in NEVs and decreases NEV levels of Aβ42, pJNK, and pERK1/2 (kinases involved in insulin resistance and neuroinflammatory pathways). In addition, changes in NAD(H) correlated with changes in canonical insulin–Akt signaling proteins and changes in pERK1/2 and pJNK. These findings support the ability of orally administered NR to augment neuronal NAD+ levels and modify biomarkers related to neurodegenerative pathology in humans. Furthermore, NEVs offer a new blood-based window into monitoring the physiologic response of NR in the brain. 相似文献