全文获取类型
收费全文 | 19480篇 |
免费 | 1411篇 |
国内免费 | 45篇 |
专业分类
耳鼻咽喉 | 121篇 |
儿科学 | 564篇 |
妇产科学 | 517篇 |
基础医学 | 2899篇 |
口腔科学 | 349篇 |
临床医学 | 2178篇 |
内科学 | 3976篇 |
皮肤病学 | 329篇 |
神经病学 | 2152篇 |
特种医学 | 615篇 |
外科学 | 1821篇 |
综合类 | 168篇 |
现状与发展 | 1篇 |
一般理论 | 20篇 |
预防医学 | 2046篇 |
眼科学 | 303篇 |
药学 | 1467篇 |
中国医学 | 56篇 |
肿瘤学 | 1354篇 |
出版年
2024年 | 26篇 |
2023年 | 249篇 |
2022年 | 388篇 |
2021年 | 686篇 |
2020年 | 471篇 |
2019年 | 758篇 |
2018年 | 737篇 |
2017年 | 580篇 |
2016年 | 576篇 |
2015年 | 634篇 |
2014年 | 819篇 |
2013年 | 1070篇 |
2012年 | 1708篇 |
2011年 | 1635篇 |
2010年 | 832篇 |
2009年 | 787篇 |
2008年 | 1278篇 |
2007年 | 1292篇 |
2006年 | 1078篇 |
2005年 | 1141篇 |
2004年 | 992篇 |
2003年 | 860篇 |
2002年 | 811篇 |
2001年 | 167篇 |
2000年 | 106篇 |
1999年 | 131篇 |
1998年 | 133篇 |
1997年 | 130篇 |
1996年 | 81篇 |
1995年 | 77篇 |
1994年 | 69篇 |
1993年 | 58篇 |
1992年 | 51篇 |
1991年 | 42篇 |
1990年 | 50篇 |
1989年 | 38篇 |
1988年 | 47篇 |
1987年 | 44篇 |
1986年 | 43篇 |
1985年 | 28篇 |
1984年 | 22篇 |
1983年 | 13篇 |
1982年 | 31篇 |
1981年 | 29篇 |
1980年 | 11篇 |
1979年 | 12篇 |
1978年 | 11篇 |
1977年 | 15篇 |
1976年 | 11篇 |
1975年 | 15篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
Edward F. McKone Emily A. DiMango Sivagurunathan Sutharsan Tara Lynn Barto Daniel Campbell Neil Ahluwalia Mark Higgins Caroline A. Owen Elizabeth Tullis 《Journal of cystic fibrosis》2021,20(2):234-242
BackgroundTezacaftor (TEZ)/ivacaftor (IVA) is an approved CFTR modulator shown to be efficacious and generally safe and well tolerated in people ≥12 years of age with cystic fibrosis (CF) homozygous for the F508del-CFTR mutation or heterozygous for the F508del-CFTR mutation and a residual function mutation. Although previous studies with IVA alone showed clinical benefits in people with CFTR gating mutations, TEZ/IVA has not yet been evaluated in a Phase 3 study of participants heterozygous for F508del-CFTR and a gating mutation (F/gating genotypes). Here, we present results from a randomized, double-blind, IVA-controlled, parallel-group, Phase 3 study assessing the efficacy, safety, and pharmacokinetics (PK) of TEZ/IVA in participants ≥12 years of age with F/gating genotypes.MethodsEnrolled participants entered a 4-week IVA run-in period to create a stable IVA baseline. Participants were then randomized to receive IVA or TEZ/IVA for 8 weeks in an active comparator treatment period (ACTP). The primary endpoint was absolute change in percent predicted forced expiratory volume in 1 second (ppFEV1). Key secondary endpoints were relative change in ppFEV1 and absolute change in CF Questionnaire–Revised respiratory domain score. Secondary endpoints included absolute change in sweat chloride (SwCl) concentration, PK parameters, and safety. All endpoints except PK parameters and safety were assessed from baseline through Week 8.ResultsSixty-nine participants (92.0%) in the IVA group and 75 participants (98.7%) in the TEZ/IVA group completed treatment. No improvements were seen in efficacy endpoints from baseline at the end of the IVA run-in period through the end of the ACTP in the IVA group. No significant differences in ppFEV1 or any key secondary endpoint were observed between the IVA and TEZ/IVA groups. SwCl concentrations decreased more in the TEZ/IVA versus IVA group during the ACTP. The safety profile and PK parameters of TEZ/IVA were consistent with those of previous studies in participants ≥12 years of age with CF.ConclusionsThis Phase 3 study showed that the dual-combination regimen of TEZ/IVA demonstrated clinical efficacy but did not have significantly greater clinical efficacy than IVA alone in participants ≥12 years of age with F/gating genotypes. However, as reported in other studies, TEZ/IVA was generally safe and well tolerated (NCT02412111). 相似文献
72.
73.
74.
Ostinelli Edoardo G. D’Agostino Armando Pesce Luisa Zangani Caroline Miragoli Paolo Durbano Federico Biffi Giuseppe Mencacci Claudio Scarone Silvio Gambini Orsola 《Zeitschrift fur Gesundheitswissenschaften》2021,29(6):1343-1355
Journal of Public Health - Neighbourhood composition is considered a social determinant of mental health that can be addressed by policymakers to improve outcomes. Deprived neighbourhoods typically... 相似文献
75.
Antoine C Liebens F Carly B Pastijn A Rozenberg S;Women's Health Initiative 《Human reproduction (Oxford, England)》2004,19(3):741-756
INTRODUCTION: Mortality due to breast cancer has been reported to be the same or even lower in HRT users than in non-users. This has been attributed to earlier diagnosis and to better prognosis. Nevertheless, more advanced disease in HRT users was reported recently by the Women's Health Initiative (WHI) study. The objective of this study was to assess, using a systematic review of current literature, whether the data of the WHI study are in contradiction to observational data. METHODS: We selected 25 studies, for which we evaluated the methodology, the characteristics of the studied populations, confounding breast cancer risk factors and prognostic indicators. RESULTS: The WHI study, showing a worsening of some prognostic parameters, is in contradiction to most published observational studies. Most observational studies are retrospective, not well matched and did not consider most confounding factors. Their methodology and selection criteria varied considerably and the number of patients was often small. No differences in the distributions of histology, grade or steroid receptors were observed in the WHI trial, while this was the case in some of the observational studies. Other parameters (S phase, protein Neu, Bcl-2 gene, protein p53 and E-cadherin, cathepsin D) were not reported in the WHI trial. CONCLUSIONS: In view of these data, the current clinical message to patients should be changed: one can no longer declare that breast cancers developed while using HRT are of better prognosis. 相似文献
76.
Twenty soft contact lens wearers were fit with a high water content, non-HEMA (ofilcon A) lens (Durasoft 4; Wesley-Jessen) on the test eye. Patients subsequently wore one of the following four lenses on the same eye: a high-water content non-HEMA (surfilcon A) lens (Permaflex 74; CooperVision); a modified mid-water content HEMA (bufilcon A) lens (Hydrocurve Elite; Sola/Barnes-Hind); a low-water content HEMA (polymacon) lens (O4; Bausch & Lomb); or a low-water content non-HEMA (crofilcon A) lens (CSI; Sola/Barnes-Hind). All lenses were worn on a daily wear basis for one month and then evaluated with the scanning electron microscope (SEM). The amount of surface deposition was measured in terms of the area of lens covered by deposit as visualized on a standard series of SEM photographs. When control was obtained for patient, eye, technique, care system, and wearing time, similar amounts of deposit were found on the two high water content soft lenses. A significantly greater amount of deposit was found on the non-HEMA high water content ofilcon A lens compared to the mid-water content modified HEMA material. However, when the patient's tendency to produce "heavy" or "light" deposits on a soft lens surface is taken into account, then for the lighter depositors the high water content non-HEMA material was found to be as acceptable as the low water content HEMA and non-HEMA materials. But for heavy depositors the high water content non-HEMA material is not recommended. 相似文献
77.
Previous research has found that drugs with affinity for (benzodiazepine) sites differ in their abilities to produce tolerance and dependence. The present study therefore investigated the effects of ligands of (BZ) sites in rats that had been rendered tolerant to a benzodiazepine. Two experiments were carried out in separate groups of rats. Behavioral changes induced by chronic infusion of triazolam (3 mg/kg/day, SC, for 14 days) via osmotic pumps were studied in animals trained on a fixed ratio 10 schedule of food presentation. Control animals were implanted with pumps containing the vehicle. Test drugs were administered IP using cumulative dosing. In one experiment triazolam decreased response rates on days 1, 2 and 3 after implantation of the pumps and tolerance developed to this depressant effect. In the other experiment, vehicle and triazolam treated rats differed in their responding during chronic infusion but differences were not statistically significant on any particular day. Flumazenil (3.0–30 mg/kg) greatly decreased rates of responding on day 11 in triazolam treated rats. This effect may represent a precipitated withdrawal syndrome. However, no withdrawal effects on operant performance were observed upon pump removal. Chronic infusion of triazolam did not affect the sensitivity of rats to alpidem on day 11 (10–100 mg/kg) whereas it abolished the stimulant effect of bretazenil (0.1–1.0 mg/kg). Chronic triazolam treatment produced tolerance to the depressant effects of triazolam (1.0–3.0 mg/kg), lorazepam (0.3–3.0 mg/kg) and zopiclone (10 mg/kg) but no tolerance to those of CL 218,872 (3.0–30 mg/kg) and zolpidem (0.3–3.0 mg/kg) when tested 3–14 days after pump removal. Differences between compounds highlighted with this model are in agreement with previous observations that these agents possess different pharmacological profiles and different potentials to induce tolerance and dependence. 相似文献
78.
79.
Level of use of 3,4-methylenedioxymethamphetamine (MDMA or Ecstasy) in humans correlates with EEG power and coherence 总被引:1,自引:0,他引:1
R. I. Dafters Frances Duffy Patrick J. O’Donnell Caroline Bouquet 《Psychopharmacology》1999,145(1):82-90
Rationale: Despite animal studies implicating 3,4-methylenedioxymethamphetamine (MDMA or Ecstasy) in serotonergic neurotoxicity, there
is little direct evidence of changes in neural function in humans who use MDMA as a recreational drug. Objective: The present study investigated whether there is a correlation between quantitative EEG variables (spectral power and coherence)
and cognitive/mood variables, and level of prior use of MDMA. Methods: Twenty-three recreational MDMA users were studied. Resting EEG was recorded with eyes closed, using a 128-electrode geodesic
net system, from which spectral power, peak frequency and coherence levels were calculated. Tests of intelligence (NART),
immediate and delayed memory, frontal function (card sort task), and mood (BDI and PANAS scales) were also administered. Pearson
correlation analyses were used to examine the relationship between these measures and the subject’s consumption of MDMA during
the previous 12-month period. Partial correlation was used to control for the use of other recreational drugs. Results: MDMA use was positively correlated with absolute power in the alpha (8–12 Hz) and beta (12–20 Hz) frequency bands, but not
with the delta (1–3 Hz) or theta (4–7 Hz) bands. MDMA use was negatively correlated with EEG coherence, a measure of synchrony
between paired cortical locations, in posterior brain sites thought to overly the main visual association pathways of the
occipito-parietal region. MDMA use did not correlate significantly with any of the mood/cognitive measures except the card
sort task, with which it was weakly negatively correlated. Conclusions: Alpha power has been shown to be inversely related to mental function and has been used as an indirect measure of brain
activation in both normal and abnormal states. Reduced coherence levels have been associated with dysfunctional connectivity
in the brain in disorders such as dementia, white-matter disease and normal aging. Our results may indicate altered brain
function correlated with prior MDMA use, and show that electroencephalography may be a cheap and effective tool for examining
neurotoxic effects of MDMA and other drugs.
Received: 19 October 1998/Final version: 12 January 1999 相似文献
80.
The Effect of Calcium Channel Antagonists on Spontaneous and Evoked Epileptiform Activity in the Rat Neocortex In Vitro 总被引:2,自引:0,他引:2
Calcium influx through voltage-activated calcium channels may play a crucial role in the propagation and maintenance of seizure activity. We have examined the contribution of various types of calcium currents to epileptogenesis by studying the effects of various calcium channel blockers on epileptiform activity. N-methyl-d-aspartate receptor-mediated epileptiform activity was induced by removal of magnesium ions superfusing the cortex, or by low-frequency stimulation of the underlying white matter. CoCl2, CdCl2 and omega-conotoxin, acting at the N- and L-type calcium channels, significantly reduced epileptiform activity. L-channel antagonists nifedipine and verapamil, and the agonist BAY K 8644, increased spontaneous bursting in cortical wedges, but had no effect upon evoked activity. The T-channel blocker NiCl2 had variable effects on epileptiform activity, whereas phenytoin consistently reduced such activity. These results suggest that calcium influx underlying epileptiform activity in the rat neocortex may occur at least partially via the activation of the N-type calcium channel. However, contributions from other calcium channel types cannot be excluded. 相似文献