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41.
Kiyohiko Sugano 《化学与生物多样性》2009,6(11):2014-2029
Bile micelles play an important role in oral absorption of low‐solubility compounds. Bile micelles can affect solubility, dissolution rate, and permeability. For the pH–solubility profile in bile micelles, the Henderson–Hasselbalch equation should be modified to take bile‐micelle partition into account. For the dissolution rate, in the Nernst–Brunner equation, the effective diffusion coefficient in bile‐micelle media should be used instead of the monomer diffusion coefficient. The diffusion coefficient of bile micelles is 8‐ to 18‐fold smaller than that of monomer molecules. For permeability, the effective diffusion coefficient in the unstirred water layer adjacent to the epithelial membrane, and the free fraction at the epithelial membrane surface should be taken into account. The importance of these aspects is demonstrated here using several in vivo and clinical oral‐absorption data of low‐solubility model compounds. Using the theoretical equations, the food effect on oral absorption is further discussed. 相似文献
42.
The sensitivity of the fluorescent dye, 3,3′-diethylthiadicarbocyanine (DiS-C2(5)), was too low for the detection of membrane potential changes in rat small intestinal membrane vesicles. Only after adding LaCl3 or after fractionation of the intestinal membranes by free-flow electrophoresis could the dye be used to monitor electrogenic Na+-dependent transport systems. It is concluded that the response of this potential-sensitive dye is influenced by the negative surface charge density of the vesicles. 相似文献
43.
M. Zamirul Hussain John C. Belton Rajendra S. Bhatnagar 《In vitro cellular & developmental biology. Plant》1978,14(9):740-745
Organ cultures of newborn rat lungs synthesize and accumulate DNA, RNA, collagen and noncollagenous proteins almost at a linear
rate for at least 5 days. During this period the synthesis of collagen consistently exceeds the synthesis of noncollagenous
proteins in a pattern similar to neonatal lung growth in vivo. Although some morphological characteristics of lung architecture
are distorted after culture, fundamental structural similarities to lungs growing in intact animals are retained. When these
cultures are maintained in atmospheres rich in oxygen, increased collagen synthesis is observed, a response similar to that
of lungs in intact animals exposed to high oxygen concentrations in vivo. Our studies suggest that lung organ cultures may
be a suitable system for investigating the biochemical aspects of lung tissue-environmental interaction.
These studies were supported in parts by NIH Grant HL-19668, a contract (68-03-2005) from the U.S. Environmental Protection
Agency, and grants from the California Lung Association. 相似文献
44.
S C Tsai R Adamik V C Manganiello M Vaughan 《Biochemical and biophysical research communications》1981,100(2):637-643
A new amino acid was isolated from the cuticle collagen of and characterized by ultraviolet, mass and nmr spectroscopies and chemical degradation. The results indicate that the compound is an isomer of trityrosine, having an ether linkage. The name “isotrityrosine” is proposed. Its structure suggests that it serves as a crosslink and plays a role in the organization of the collagen structure. 相似文献
45.
L. Chaerle F. De Boever M. Van Montagu & D. Van Der Straeten 《Plant, cell & environment》2001,24(1):15-25
Pending cell death was visualized by thermographic imaging in bacterio‐opsin transgenic tobacco plants. Cell death in these plants was characterized by a complex lesion phenotype. Isolated cell death lesions were preceded by a colocalized thermal effect, as previously observed at sites infected by tobacco mosaic virus (TMV) ( Chaerle et al. 1999 Nature Biotechnology 17, 813–816). However, in most cases, a coherent front of higher temperature, trailed by cell death, initiated at the leaf base and expanded over the leaf lamina. In contrast to the homogenous thermal front, cell death was first visible close to the veins, and subsequently appeared as discrete spots on the interveinal tissue, as cell death spread along the veins. Regions with visible cell death had a lower temperature because of water evaporation from damaged cells. In analogy with previous observations on the localized tobacco–TMV interaction ( Chaerle et al. 1999 ), the kinetics of thermographic and continuous gas exchange measurements indicated that stomatal closure preceded tissue collapse. Localized spontaneous cell death could also be presymptomatically visualized in the Arabidopsis lsd2 mutant. 相似文献
46.
Antibodies to human amyloid precursor protein (APP695) and beta‐amyloid peptide (Aβ1‐42) were used to determine timing of amyloidosis in the brain of kokanee salmon (Oncorhynchus nerka kennerlyi) in one of four reproductive stages: immature (IM), maturing (MA), sexually mature (SM), and spawning (SP), representing a range of aging from somatically mature but sexually immature to spawning and somatic senescence. In IM fish, immunoreactive (ir) intracellular APP occurred in 18 of 23 brain regions. During sexual maturation and aging, the number of neurons expressing APP increased in 11 of these APP‐ir regions. Aβ‐ir was absent in IM fish, present in seven regions in MA fish, moderately abundant in 15 regions in SM fish, and was most abundant in all brain regions of SP fish exhibiting Aβ‐ir. Intracellular APP‐ir was observed in brain regions involved in sensory integration, olfaction, vision, stress responses, reproduction, and coordination. Intra‐ and extracellular Aβ1‐42 immunoreactivity (Aβ‐ir) was present in all APP‐ir regions except the nucleus lateralis tuberis (hypothalamus) and Purkinje cells (cerebellum). APP‐ir and Aβ deposition increase during aging. APP‐ir is present in IM fish; Aβ‐ir usually appears first in MA or SM fish and increases in SM fish as does APP‐ir. Extracellular Aβ deposition dramatically increases between SM and SP stages (1–2 weeks) in all fish, indicating an extremely rapid and synchronized process. Rapid senescence observed in pacific salmon could make them a useful model to investigate timing of amyloidosis and neurodegeneration during brain aging. © 2002 Wiley Periodicals, Inc. J Neurobiol 53: 11–20, 2002 相似文献
47.
《FEBS letters》1988,240(1-2):88-94
Four subtypes of muscarinic acetylcholine receptor (mAChR) were stably expressed in neuroblastoma-glioma hybrid cells (NG108-15). By combining fluorescent indicator dye (fura-2) studies with electrophysiological measurements it is shown that stimulation of mAChR I and mAChR III readily leads to release of calcium from intracellular stores and to associated conductance changes, whereas stimulation of mAChR II and mAChR IV exerts no such effect. Dose-response curves describing the amplitude or the delay of the calcium rise induced by acetylcholine suggest that the apparent affinity of mAChR III for its agonist is higher by about one order of magnitude than that of mAChR I. Ionic substitution experiments and current fluctuation analysis indicate that calcium activates a K+-specific conductance of ‘small’ single-channel amplitude similar to the SK type [1]. Furthermore, an outward current (M current) suppressed by activation of mAChR I and mAChR III has a single-channel amplitude corresponding to a conductance of approximately 3 pS. 相似文献
48.
When hemolymph is taken from Ascaris lumbricoides at the time the worm is collected from pigs, it contains acetic, propionic, 2-methylbutyric, n-valeric, 2-methylvaleric, and succinic acid radicals; tiglic acid is absent. 相似文献
49.
Background
Eosinophilia plays the major role in the pathogenesis of asthma and correlates with the up‐regulation of eotaxin, which, together with interleukin (IL)‐5, is important for differentiation, chemo‐attraction, degranulation, and survival of eosinophils in local tissue. In a previous study, we found that administration of lentivirus‐delivered short hairpin RNA (shRNA) to suppress the expression of IL‐5 inhibited airway inflammation. The present study aimed to investigate the role of eotaxin shRNA and the synergistic effect of eotaxin and IL‐5 shRNAs on airway inflammation in an ovalbumin (OVA)‐induced murine model of asthma.Methods
Lentivirus‐delivered shRNAs were used to suppress the expression of eotaxin and/or IL‐5 in local tissue in an OVA‐induced murine asthma model.Results
Intra‐tracheal administration of lentivirus containing eotaxin shRNA expressing cassette (eoSEC3.3) efficiently moderated the characteristics of asthma, including airway hyper‐responsiveness, cellular infiltration of lung tissues, and eotaxin and IL‐5 levels in bronchio‐alveolar lavage fluid. Administration of lentiviruses expressing IL‐5 or eotaxin shRNAs (IL5SEC4 + eoSEC3.3) also moderated the symptoms of asthma in a mouse model.Conclusions
Local delivery of lentiviruses expressing IL‐5 and eotaxin shRNAs provides a potential tool in moderating airway inflammation and also has the potential for developing clinical therapy based on the application of shRNAs of chemokines and cytokines involved in T helper 2 cell inflammation and eosinophilia. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献50.
Aquaspirillum magnetotacticum MS-1 cells cultured microaerobically (dissolved O2 tension 1% of saturation), expressed proteins with superoxide dismutase (SOD) activity. The majority (roughly 95%) of total cell superoxide dismutase activity was located in the cell periplasm with little or no activity in the cell cytoplasm. Irontype SOD (FeSOD) contributed 88% of the total activity activity detected, although a manganese-type SOD (MnSOD) was present in the periplasm as well. Cells cultured at a higher dissolved O2 tension (10% of saturation) expressed increased activity of the MnSOD relative to that of the FeSOD. 相似文献