首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   3097篇
  免费   168篇
  国内免费   20篇
耳鼻咽喉   35篇
儿科学   113篇
妇产科学   57篇
基础医学   264篇
口腔科学   58篇
临床医学   300篇
内科学   468篇
皮肤病学   53篇
神经病学   216篇
特种医学   103篇
外科学   197篇
综合类   661篇
一般理论   2篇
预防医学   287篇
眼科学   44篇
药学   204篇
中国医学   1篇
肿瘤学   222篇
  2023年   24篇
  2022年   40篇
  2021年   50篇
  2020年   50篇
  2019年   64篇
  2018年   72篇
  2017年   71篇
  2016年   56篇
  2015年   76篇
  2014年   97篇
  2013年   144篇
  2012年   157篇
  2011年   157篇
  2010年   129篇
  2009年   103篇
  2008年   216篇
  2007年   270篇
  2006年   235篇
  2005年   225篇
  2004年   176篇
  2003年   150篇
  2002年   129篇
  2001年   60篇
  2000年   64篇
  1999年   73篇
  1998年   89篇
  1997年   38篇
  1996年   27篇
  1995年   27篇
  1994年   24篇
  1993年   23篇
  1992年   15篇
  1991年   4篇
  1990年   13篇
  1989年   11篇
  1988年   13篇
  1987年   8篇
  1986年   10篇
  1985年   8篇
  1984年   12篇
  1983年   6篇
  1982年   8篇
  1981年   11篇
  1980年   6篇
  1979年   8篇
  1978年   3篇
  1977年   6篇
  1976年   5篇
  1927年   2篇
  1909年   2篇
排序方式: 共有3285条查询结果,搜索用时 15 毫秒
91.
Mandatory reporting to the social services is required by dental professionals when suspicion of child abuse or neglect occurs. The objective of this study was to analyze the recommendations previously made by the Ombudsman for Children in Sweden. The aim was to study the association between having guidelines and the inclination to report to the social services and also the association between management of multiple missed appointmens and reports to the social service. A web-based questionnaire was sent to the clinical department heads (CDH) of all PDS in Sweden, distributed and authorized by The Ombudsman for Children in Sweden. The response frequency was 95% and all county councils of Sweden were represented. The results showed regional differences regarding management of suspected child abuse, neglect and dental neglect. Clinical department heads that had reported to the social services more often had guidelines on child abuse and neglect (p < 0.000). Management of repeated missed appointments varied between clinics. Those who never had made a report to the social services more often stated that the reason for missed appointments was parental negligence (p = 0.004) and less often thought it was an actual maltreatment (p = 0.003), and they more often rescheduled when a child repeatedly missed an appointment (p = 0.013). Sixty-four percent of the clinical department heads requested additional support in this matter. In conclusion, public dental service clinics in Sweden are significantly more likely to report to the social services if guidelines regarding child abuse and neglect are available.  相似文献   
92.

Background

Febrile urinary tract infections (fUTIs) are common after kidney transplantation (KTx); however, prospective data in a multicenter pediatric cohort are lacking. We designed a prospective registry to record data on fUTI before and after pediatric KTx.

Methods

Ninety-eight children (58 boys and 40 girls)?≤?18 years from 14 mid-European centers received a kidney transplant and completed a 2-year follow-up.

Results

Posttransplant, 38.7 % of patients had at least one fUTI compared with 21.4 % before KTx (p?=?0.002). Before KTx, fUTI was more frequent in patients with congenital anomalies of kidneys and urinary tract (CAKUT) vs. patients without (38 % vs. 12 %; p?=?0.005). After KTx, fUTI were equally frequent in both groups (48.7 % vs. 32.2 %; p?=?0.14). First fUTI posttransplant occurred earlier in boys compared with girls: median range 4 vs. 13.5 years (p?=?0.002). Graft function worsened (p?<?0.001) during fUTI, but no difference was recorded after 2 years. At least one recurrence of fUTI was encountered in 58 %.

Conclusion

This prospective study confirms a high incidence of fUTI after pediatric KTx, which is not restricted to patients with CAKUT; fUTIs have a negative impact on graft function during the infectious episode but not on 2-year graft outcome.
  相似文献   
93.
94.
Intelligent behavior depends on the ability to suppress inappropriate actions and resolve interference between competing responses. Recent clinical and neuroimaging evidence has demonstrated the involvement of prefrontal, parietal, and premotor areas during behaviors that emphasize conflict and inhibition. It remains unclear, however, whether discrete subregions within this network are crucial for overseeing more specific inhibitory demands. Here we probed the functional specialization of human prefrontal cortex by combining repetitive transcranial magnetic stimulation (rTMS) with integrated behavioral measures of response inhibition (stop-signal task) and response competition (flanker task). Participants undertook a combined stop-signal/flanker task after rTMS of the inferior frontal gyrus (IFG) or dorsal premotor cortex (dPM) in each hemisphere. Stimulation of the right IFG impaired stop-signal inhibition under conditions of heightened response competition but did not influence the ability to suppress a competing response. In contrast, stimulation of the right dPM facilitated execution but had no effect on inhibition. Neither of these results was observed during rTMS of corresponding left-hemisphere regions. Overall, our findings are consistent with existing evidence that the right IFG is crucial for inhibitory control. The observed double dissociation of neurodisruptive effects between the right IFG and right dPM further implies that response inhibition and execution rely on distinct neural processes despite activating a common cortical network.  相似文献   
95.
Johnston TE 《Physical therapy》2007,87(9):1243-1252
Individuals with physical disabilities may benefit from cycling interventions, which could address impairments while potentially minimizing stress on joints. Improvements in impairments may then have an impact on mobility, activity, and participation. Cycling studies with adults and children who are healthy have shown that many factors can influence the biomechanics of cycling. These factors include seat height, crank arm length, foot position, cadence, and workload. Knowledge of these factors is important for rehabilitation professionals who prescribe cycling as an intervention for individuals with disabilities, because changing these factors can potentially influence the therapeutic outcomes. In addition, further research is needed to fully understand the effect of these factors on individuals with disabilities.  相似文献   
96.
The post-transplant outcomes of patients with Model for End-stage Liver Disease (MELD) score primarily driven by renal dysfunction are poorly understood. This was a retrospective cohort study of liver transplant (LT) alone recipients between 2005 and 2017 using the United Network for Organ Sharing (UNOS) database. The proportion of MELD Sodium score attributable to creatinine (“KidneyMELD”) was calculated: (9.57 × ln (creatinine) × 100)/(MELD-Na − 6.43). The association of KidneyMELD with (a) all-cause mortality and (b) estimated glomerular filtration rate ≤30 mL/min/1.732 at 1-year post-LT were evaluated. Recipients with KidneyMELD ≥50% had a 52% higher risk of post-LT mortality (adjusted hazard ratio 1.52 vs KidneyMELD 0%, 95% CI: 1.36-1.69; P < .001). This risk was significantly greater for older patients, particularly when >50 years at LT (interaction P < .001). KidneyMELD ≥50% was also associated with an 11-fold increase in the odds of advanced renal dysfunction at 1-year post-LT (adjusted odds ratio 11.53 vs KidneyMELD 0%; 95% CI 8.9-14.93; P < .001). Recipients prioritized for LT primarily on the basis of renal dysfunction have marked post-LT mortality and morbidity independent of MELD Sodium score. The implications of these results in the context of the new UNOS “safety net” kidney transplant policy require further study.  相似文献   
97.

Purpose

The purpose of this study were firstly to characterize the population pharmacokinetics of artesunate (ARS) and its active metabolite dihydroartemisinin (DHA) in patients with metastatic breast cancer during long-term (>3 weeks) daily oral ARS administration and secondly to study the relationship between salivary and plasma concentrations of DHA.

Methods

Drug concentration-time data from 23 patients, receiving oral ARS (100, 150, or 200 mg OD), was analyzed using nonlinear mixed effects modeling. A combined drug-metabolite population pharmacokinetic model was developed to describe the plasma pharmacokinetics of ARS and DHA in plasma. Saliva drug concentrations were incorporated as being directly proportional to plasma concentrations.

Results

A first-order absorption model for ARS linked to a combined two-compartment disposition model for ARS and one-compartment disposition model for DHA provided the best fit to the data. No covariates were identified that could explain between-subject variability. A time-dependent increase in apparent elimination clearance of DHA was observed. Salivary DHA concentrations were proportionally correlated with total DHA plasma concentrations, with an estimated slope factor of 0.116.

Conclusions

Population pharmacokinetics of ARS and DHA in patients with breast cancer was well described by a combined drug-metabolite model without any covariates and with an increase in apparent elimination clearance of DHA over time. The estimated DHA saliva/plasma ratio was in good agreement with the reported DHA unbound fraction in human plasma. Saliva ARS concentrations correlated poorly with plasma concentrations. This suggests the use of saliva sampling for therapeutic drug monitoring of DHA. However, further studies are warranted to investigate the robustness of this approach.  相似文献   
98.

Introduction

Smoking during pregnancy is common, and quitting at any point during pregnancy can yield benefits to both the fetus and mother. Smoking cessation is typically followed by withdrawal symptoms and a strong desire to smoke, both of which are likely to contribute to relapse. Research has shown that a bout of exercise minimizes cravings and tobacco withdrawal symptoms (TWS) after temporary abstinence in smokers, but these findings have not been replicated in pregnant smokers. This study examined the effect of 20 min of exercise on cravings (primary outcome) and TWS (secondary outcomes) among temporary abstinent, inactive pregnant smokers.

Methods

Thirty female smokers (Mean(M) age = 25.7 years, Standard Deviation(SD) = 5.5; M weeks pregnant = 18.2, SD = 5.3; Fagerstrom Test for Cigarette Dependence = 3.3, SD = 2.2; M 9.3 cigarettes/day, SD = 4.7; M hours abstained = 17.2, SD = 2.8) were randomized to 20 min of mild-to-moderate intensity exercise (EC; n = 14) or passive (PC; n = 16) condition. Cravings and TWS were assessed immediately before, during (at 10 min), immediately post, and at 10, 20, and 30 min post-condition.

Results

A 2 (condition) × 6 (time) repeated measures ANOVA revealed that the EC significantly (p < 0.05) reduced cravings (?2 = 0.46) compared with the PC, across time. Non-significant, but nevertheless, large effects were evident favouring the EC over time for TWS restlessness (?2 = 0.34), stress (?2 = 0.24), irritability (?2 = 0.21), tension (?2 = 0.15), and depression (?2 = 0.14).

Conclusions

Consistent with previous research, this study reveals that in pregnant smokers, a bout of exercise is associated with a reduction in cravings and similar patterns exist for TWS. Therefore, exercise may have the potential to assist in the initial stages of smoking cessation attempts during pregnancy.  相似文献   
99.
100.
Translational control is a key level in regulating gene expression in oocytes and eggs because many mRNAs are synthesized and stored during oogenesis for latter use at various stages of oocyte maturation and embryonic development. Understanding the molecular mechanisms that underlie this translational control is therefore crucial. Another important issue is the evolutionary conservation of these mechanisms--in other words the determination of their universal and specific aspects. We report here a comparative analysis of a translational repression mechanism that depends on the EDEN (embryo deadenylation element) element. This small cis-acting element, localized in the 3' untranslated region of c-mos and Eg mRNAs, was shown to be involved in a deadenylation process. We demonstrate here that in Xenopus embryos, mRNAs that contain an EDEN are translationally repressed. Next, transgenic flies were used to study the effect of the EDEN motif on translation in Drosophila oocytes. We show that this element also causes the translational repression of a reporter gene in Drosophila demonstrating that the EDEN-dependent translational repression is functionally conserved between Xenopus and Drosophila.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号