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141.
Two inward-rectifier K+ channels, ROMK2 (Kir1.1b) and IRK1 (Kir2.1), were expressed in Xenopus oocytes and their gating properties were studied in cell-attached membrane patches. The gating properties depended strongly
on the ion being conducted (K+, NH4
+, Rb+, or Tl+), suggesting tight coupling between permeation and gating. Mean open times were strongly dependent on the nature of the conducted
ion. For ROMK2 the order from the longest to the shortest times was K+ > Rb+ > Tl+ > NH4
+. For IRK1 the sequence was K+ > NH4
+ > Tl+. In both cases the open times decreased monotonically as the membrane voltage was hyperpolarized. Both the absolute values
and the voltage dependence of closed times were dependent on the conducted species. ROMK2 showed a single closed state whose
mean lifetimes were biphasic functions of voltage. The maxima were at various voltages for different ions. IRK1 had at least
two closed states whose lifetimes decreased monotonically with K+, increased monotonically with Tl+, and were relatively constant with NH4
+ as the conducted ion. We explain the ion-dependence of gating by assuming that the ions bind to a site within the permeation
pathway, resulting in a stable, ion-dependent, closed state of the channel. The patterns of voltage-dependence of closed-state
lifetimes, which are specific for different ions, can be explained by variations in the rate at which the bound ions leave
the pore toward the inside or the outside of the cell.
Received: 18 April 2001/Revised: 28 June 2001 相似文献
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Min Soo Byun Song E. Kim Jinsick Park Dahyun Yi Young Min Choe Bo Kyung Sohn Hyo Jung Choi Hyewon Baek Ji Young Han Jong Inn Woo Dong Young Lee Alzheimer’s Disease Neuroimaging Initiative 《PloS one》2015,10(11)
We aimed to identify and characterize subtypes of Alzheimer’s disease (AD) exhibiting different patterns of regional brain atrophy on MRI using age- and gender-specific norms of regional brain volumes. AD subjects included in the Alzheimer''s Disease Neuroimaging Initiative study were classified into subtypes based on standardized values (Z-scores) of hippocampal and regional cortical volumes on MRI with reference to age- and gender-specific norms obtained from 222 cognitively normal (CN) subjects. Baseline and longitudinal changes of clinical characteristics over 2 years were compared across subtypes. Whole-brain-level gray matter (GM) atrophy pattern using voxel-based morphometry (VBM) and cerebrospinal fluid (CSF) biomarkers of the subtypes were also investigated. Of 163 AD subjects, 58.9% were classified as the “both impaired” subtype with the typical hippocampal and cortical atrophy pattern, whereas 41.1% were classified as the subtypes with atypical atrophy patterns: “hippocampal atrophy only” (19.0%), “cortical atrophy only” (11.7%), and “both spared” (10.4%). Voxel-based morphometric analysis demonstrated whole-brain-level differences in overall GM atrophy across the subtypes. These subtypes showed different progression rates over 2 years; and all subtypes had significantly lower CSF amyloid-β1–42 levels compared to CN. In conclusion, we identified four AD subtypes exhibiting heterogeneous atrophy patterns on MRI with different progression rates after controlling the effects of aging and gender on atrophy with normative information. CSF biomarker analysis suggests the presence of Aβ neuropathology irrespective of subtypes. Such heterogeneity of MRI-based neuronal injury biomarker and related heterogeneous progression patterns should be considered in clinical trials and practice with AD patients. 相似文献
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Sung O. Park Heather L. Wamsley Kyungmi Bae Zhongbo Hu Xiaomiao Li Se-woon Choe William B. Slayton S. Paul Oh Kay-Uwe Wagner Peter P. Sayeski 《PloS one》2013,8(3)
Germline deletion of Jak2 in mice results in embryonic lethality at E12.5 due to impaired hematopoiesis. However, the role that Jak2 might play in late gestation and postnatal life is unknown. To understand this, we utilized a conditional knockout approach that allowed for the deletion of Jak2 at various stages of prenatal and postnatal life. Specifically, Jak2 was deleted beginning at either mid/late gestation (E12.5), at postnatal day 4 (PN4), or at ∼2 months of age. Deletion of Jak2 beginning at E12.5 resulted in embryonic death characterized by a lack of hematopoiesis. Deletion beginning at PN4 was also lethal due to a lack of erythropoiesis. Deletion of Jak2 in young adults was characterized by blood cytopenias, abnormal erythrocyte morphology, decreased marrow hematopoietic potential, and splenic atrophy. However, death was observed in only 20% of the mutants. Further analysis of these mice suggested that the increased survivability was due to an incomplete deletion of Jak2 and subsequent re-population of Jak2 expressing cells, as conditional deletion in mice having one floxed Jak2 allele and one null allele resulted in a more severe phenotype and subsequent death of all animals. We found that the deletion of Jak2 in the young adults had a differential effect on hematopoietic lineages; specifically, conditional Jak2 deletion in young adults severely impaired erythropoiesis and thrombopoiesis, modestly affected granulopoiesis and monocytopoiesis, and had no effect on lymphopoiesis. Interestingly, while the hematopoietic organs of these mutant animals were severely affected by the deletion of Jak2, we found that the hearts, kidneys, lungs, and brains of these same mice were histologically normal. From this, we conclude that Jak2 plays an essential and non-redundant role in hematopoiesis during both prenatal and postnatal life and this has direct implications regarding the inhibition of Jak2 in humans. 相似文献
147.
Comparative study of Helicobacter pylori eradication rates of concomitant therapy vs modified quadruple therapy comprising proton‐pump inhibitor,bismuth, amoxicillin,and metronidazole in Korea 下载免费PDF全文
148.
Myong-Chol Ko Nam-Chol Kim Song-Il Choe Gwang-Hyok So Pong-Ryol Jang Yong-Jin Kim Il-Gwang Kim Jian-Bo Li 《Plasmonics (Norwell, Mass.)》2018,13(1):39-46
We investigated theoretically the exciton–plasmon coupling effects on the population dynamics and the absorption properties of a hybrid nanosystem composed of a metal nanoparticle (MNP) and a V-type three-level semiconductor quantum dot (SQD), which are created by the interaction with the induced dipole moments in the SQD and the MNP, respectively. Excitons of the SQD and the plasmons of the MNP in such a hybrid nanosystem could be coupled strongly or weakly to demonstrate novel properties of the hybrid system. We also find that the gain happens in such a hybrid system, because of the coherent interaction between the SQD and the MNP. Our results show that the non-linear optical response of the hybrid nanosystem can be greatly enhanced or depressed due to the exciton–plasmon couplings. 相似文献
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Shah Ahmed Belal Allur Subramaniyan Sivakumar Da Rae Kang Sangbuem Cho Ho Sung Choe 《Animal cells and systems.》2018,22(5):324-333
This study was performed to elucidate the effects of linoleic acid (LA), oleic acid (OA) and their combination (LA?+?OA) on cell proliferation, apoptosis, necrosis, and the lipid metabolism related gene expression in bovine satellite cells (BSCs), isolated from bovine muscles. Cell viability was significantly increased with the OA and LA treatment. Furthermore, LA?+?OA enhanced cell proliferation in a dose-dependent manner (10 to 100?µM), whereas it lowered at 250?µM. In addition, a cell-cycle analysis showed that 100?µM of LA and OA markedly decreased the G0/G1 phase proportion (62.58% and 61.33%, respectively), compared to controls (68.02%), whereas the S-phase cells’ proportion was increased. The ratio of G2/M phase cells was not significantly different among the groups. Moreover, analyses with AO/EtBr staining showed that no apoptosis occurred. Necrosis were determined by flow cytometry using Annexin V-FITC/PI staining which revealed no early apoptosis in the cells pretreated with LA or OA, but occurred in the LA?+?OA group. We also analyzed the mRNA expression of lipid metabolizing genes such as peroxisome proliferator receptor alfa (PPARα), peroxisome proliferator receptor gamma (PPARγ), acyl-CoA oxidase (ACOX), lipoprotein lipase (LPL), carnitine palmitoyl transferase (CPT-1), and fatty-acid binding protein4 (FABP4), which were upregulated in LA or OA treated cells compared to the control group. In essence, LA and OA alone promote the cell proliferation without any apoptosis and necrosis, which might upregulate the lipid metabolism related gene expressions, and increase fatty-acid oxidation in the BSCs’ lipid metabolism. 相似文献