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21.
Complement fixation (CF) was compared to hemagglutination inhibition (HI) as a method for identifying antibody responses to influenza virus vaccination. CF assays were performed at two different laboratories using paired (pre- and postvaccination) sera from 38 vaccinated laboratory employees; HI assays were performed at a third laboratory. As expected, most vaccinees (31/38 = 82%) responded to at least one of three influenza virus antigens as measured by HI. In contrast, only 21% (8/38) of vaccinees showed a response by CF at laboratory 1, and only 29% (11/38) showed a response by CF at laboratory 2. These findings indicate that due to low sensitivity, CF assays should not be used to assess the antibody response to influenza virus vaccination. 相似文献
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Noradrenergic modulation of firing pattern in guinea pig and cat thalamic neurons, in vitro 总被引:8,自引:0,他引:8
1. The electrophysiological actions of norepinephrine (NE) in the guinea pig and cat thalamus were investigated using intracellular recordings from neurons of in vitro thalamic slices. 2. Application of NE to neurons of the lateral and medial geniculate nuclei, nucleus reticularis, anteroventral nucleus, and the parataenial (PT) nucleus resulted in a slow depolarization associated with a 2- to 15-nS decrease in input conductance and an increase in the slow membrane time constant from an average of 27.7 to 37.7 ms. The slow depolarization was not abolished by blockade of synaptic transmission, indicating that it was a direct (postsynaptic) effect. 3. The reversal potential of the NE-induced slow depolarization varied as a Nernstian function of extracellular potassium concentration ([K]o), indicating that it is due to a decrease in potassium conductance. This conclusion was supported by the finding that the amplitude of the NE-evoked depolarization was affected by changes in [K]o between 0.5 and 5.0 mM as expected for a K-mediated response. 4. Neurons of the PT nucleus displayed unusually large afterhyperpolarizations (AHPs) in comparison to cells in other thalamic nuclei. NE application to PT neurons caused not only a marked slow depolarization and decreased conductance, but also selectively reduced the slow AHP. 5. The NE-induced slow depolarization effectively suppressed burst firing and promoted the occurrence of single spike activity. NE-induced reduction of the slow AHP in PT neurons was accompanied by a decrease in spike frequency accommodation and the emergence of a slow afterdepolarization. 6. We suggest that through these electrophysiological actions, NE can effectively inhibit the generation of thalamocortical rhythms and greatly facilitate the faithful transfer of information through the thalamus to the cerebral cortex. 相似文献
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The mechanism underlying outward chloride transport in guinea pig cingulate cortical neurons of in vitro slices was characterized with respect to its pharmacological antagonists and anion selectivity, and the nature of other ion movements coupled to Cl- transport. Changes in intracellular Cl- concentration, following iontophoresis of Cl- from KCl-filled intracellular recording electrodes, were estimated from changes in the amplitude of GABAergic, Cl(-)-mediated inhibitory postsynaptic potentials (IPSPs). The rate of outward Cl- transport was found to be reduced by bumetanide but not by SITS. SCN-, but not NO3-, was found to be actively transported. Increasing the extracellular K+ concentration ([K+]o) from 2.5 to 10 mM was found to inhibit Cl- extrusion. These data suggest that active Cl- extrusion from mammalian cortical neurons is mediated by an outwardly directed chloride/cation cotransport mechanism. Inhibition of this process by elevated [K+]o may be important in epilepsy. 相似文献
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Prince Kevin Danieles Marina Ybarra Andraea Van Hulst Tracie A. Barnett Marie-Ève Mathieu Lisa Kakinami Olivier Drouin Jean-Luc Bigras Mélanie Henderson 《Obesity research & clinical practice》2021,15(2):157-162
IntroductionAttrition in pediatric weight management programs is notoriously high. Greater understanding of its determinants is needed to inform retention strategies. We identified determinants of attrition in CIRCUIT, a healthy lifestyle intervention program for youth at risk of cardiovascular disease.MethodsA one-arm intervention study of children aged 4-18 years who initiated the CIRCUIT program in the first five years of its existence (N = 403). We defined attrition as attending the baseline visit but ceasing attendance prior to the 1-year follow-up. Potential determinants of dropout included the child’s age, sex, ethnicity, body mass index (BMI) z-score, family socio-demographic characteristics, and estimated driving time to the program, all measured at baseline. Associations were estimated bivariately, using chi-squared- and t-tests, and simultaneously in a multivariable logistic regression model.ResultsOf the 403 participants who started the program, 198 (49%) dropped out within 12 months of enrollment. Youth who dropped out were older (mean age 12.8y vs. 11.3y; p < 0.01), were less likely to live with both parents (62% vs. 71%; p = 0.05), and to have mothers who had completed high school (79% vs. 88%; p = 0.01). No group differences were observed for sex, ethnicity, baseline BMI z-score, fathers’ education, or driving time to the program. In multivariate models, only older age at initiation of the intervention (OR: 1.2; CI: 1.1,1.3) and lower maternal education (OR: 2.0; CI: 1.0,3.8) were associated with dropout.ConclusionImproved tailoring of interventions to older pediatric participants and to families of lower maternal education may help reduce attrition in CIRCUIT and similar lifestyle intervention programs. 相似文献
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Transcranial freeze lesions in neonatal rat pups produce microgyri and adjacent epileptogenic regions of neocortex that can be used to model human polymicrogyria. The hypothesis that the presence of microgyri is associated with abnormal cortical organization occurring within as well as adjacent to the microgyri was tested by creating microgyri within the face representation of somatosensory cortex. Microgyri were associated with a widespread disruption of the stereotypic whisker barrel field pattern delineated with cytochrome oxidase (CO) staining. CO-stained patches resembling barrel hollows were absent within the microgyrus, and were abnormally shaped and distributed outside of the microgyrus. Adjacent Nissl- or acetylcholinesterase-stained sections demonstrated that both cell clusters and thalamocortical afferents contributed to the abnormally organized paramicrogyral zone identified in CO-stained sections. Field potential recordings showed that this region of heavy CO staining corresponded to the epileptogenic zone adjacent to the microgyrus. Results support our hypothesis that the epileptogenic paramicrogyral zone develops an abnormal organization of cell clusters and thalamocortical projections that could contribute to epileptogenesis in the paramicrogyral zone. 相似文献
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The role of estrogen in the regulation of calcium balance is still poorly understood. A calcium balance study was performed
to examine the effects of estrogen status in relation to fecal calcium loss as a component of bone loss after oophorectomy
(OOX) in the mature rat. The components of the classic calcium balance were compared with calcium balance estimates obtained
from whole body bone density. Six month or older Sprague Dawley rats were allocated to either a sham-operated or OOX group
and fed a 0.1% calcium diet. The bone mineral density (BMD) and bone mineral content (BMC) were measured at baseline, 6 weeks,
and 9 weeks. A calcium balance was done for 6 days before and 6 weeks post OOX. The fall in BMD from baseline to 9 weeks in
the OOX group was significantly greater than in the sham-operated group. The calcium balance was more negative at baseline
than at 6 weeks in both groups of animals because they had not adapted to the low calcium diet. However, the increase in calcium
balance was significantly less in the OOX animals than in the sham-operated animals. The greater the rise in calcium balance
from the baseline to the 6 weeks balance the less the fall in the calcium content of the whole body (Spearman correlation:
r = 0.604 P = 0.008). The fall in fecal calcium, but not urine calcium or calcium consumed, was negatively correlated with
the change in whole body BMC (Spearman correlation: fecal calcium r =−0.763 P = 0.001). Thus, the primary effect of estrogen
deficiency on calcium balance in the mature rat appears to be calcium flux in the bowel, rather than renal calcium handling.
Received: 16 April 1997 / Accepted: 22 September 1998 相似文献
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