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   3418篇
  免费   121篇
  国内免费   14篇
耳鼻咽喉   39篇
儿科学   126篇
妇产科学   24篇
基础医学   379篇
口腔科学   41篇
临床医学   187篇
内科学   825篇
皮肤病学   65篇
神经病学   274篇
特种医学   176篇
外科学   547篇
综合类   18篇
预防医学   150篇
眼科学   75篇
药学   265篇
中国医学   4篇
肿瘤学   358篇
  2022年   20篇
  2021年   47篇
  2020年   31篇
  2019年   29篇
  2018年   48篇
  2017年   27篇
  2016年   61篇
  2015年   45篇
  2014年   76篇
  2013年   98篇
  2012年   161篇
  2011年   205篇
  2010年   111篇
  2009年   114篇
  2008年   191篇
  2007年   190篇
  2006年   182篇
  2005年   228篇
  2004年   226篇
  2003年   204篇
  2002年   217篇
  2001年   55篇
  2000年   33篇
  1999年   54篇
  1998年   50篇
  1997年   65篇
  1996年   59篇
  1995年   57篇
  1994年   49篇
  1993年   48篇
  1992年   48篇
  1991年   42篇
  1990年   29篇
  1989年   38篇
  1988年   38篇
  1987年   16篇
  1986年   30篇
  1985年   31篇
  1984年   33篇
  1983年   20篇
  1982年   16篇
  1981年   16篇
  1980年   15篇
  1979年   10篇
  1978年   19篇
  1975年   9篇
  1957年   23篇
  1956年   16篇
  1955年   17篇
  1954年   11篇
排序方式: 共有3553条查询结果,搜索用时 31 毫秒
91.

Objective

To explore whether synovitis and bone lesions in the wrists and finger joints visualized by plain magnetic resonance imaging (MRI)-based findings correspond exactly or not to those judged by gadolinium-diethylenetriamine pentaacetic acid (Gd-DTPA)-enhanced MRI-based findings.

Methods

Magnetic resonance imaging of the wrists and finger joints of both hands were examined in 51 early-stage rheumatoid arthritis (RA) patients whose median disease duration from the onset of articular manifestations to entry was 5?months, by both plain (T1 and short-time inversion recovery images) and Gd-DTPA-enhanced MRI (post-contrast fat-suppressed T1-weighted images) simultaneously. We focused on 15 sites per hand, to examine the presence of synovitis and bone lesions (bone edema and bone erosion). Gd-DTPA-enhanced MRI-based findings were considered “true” lesions, and we evaluated the accuracy of plain MRI-based findings in comparison to Gd-DTPA-enhanced MRI-based findings.

Results

Synovitis, judged by plain MRI-based findings, appeared as false-positive at pretty frequency; thus, the specificity, positive predictive value and accuracy of the findings were low. The rate of enhancement (E-rate) in false-positive synovitis sites was significantly low compared with true-positive synovitis sites where Gd-DTPA enhancement appears. In contrast to synovitis, the false-positivity of bone lesions, judged by plain MRI-based findings, was very low compared with Gd-DTPA-enhanced MRI-based findings.

Conclusion

Synovitis judged by plain MRI-based findings is sometimes considered false-positive especially in sites where synovitis is mild. However, plain MRI is effective in identifying bone lesions in the wrist and finger joints in early-stage RA.  相似文献   
92.
Background contextA digit/rib-like ectopic bone is a rare congenital anomaly that is most commonly seen in the thorax or pelvis. There is a single report of an adult possessing a phalanx-like bone in the cervical region; however, whether the abnormal bone was congenital or acquired remains elusive.PurposeTo elucidate that a phalanx-like bone in the cervical region represents a congenital anomaly.Study designCase report.MethodsReport of the imaging findings in a neonate with a palpable bone projection in the posterior neck.ResultsPlain radiographs demonstrated an ectopic bone posterior to the spinous process of the C5 vertebra. Three-dimensional computed tomography demonstrated that the anomalous bone was attached to the left lamina of the C5 vertebra and that there was abnormal segmentation of the left side of the cervical spine.ConclusionsThe anomalous bone in the neck is a congenital malformation that is accompanied by the maldevelopment of the cervical spine.  相似文献   
93.
94.
ABSTRACT

Individuals with schizophrenia exhibit cognitive impairments, which are related to impairments in social functions. This study investigated the effects of cognitive remediation on cognitive, social, and daily living impairment. Participants were individuals with schizophrenia between 20 and 60 years old (N?=?44). Participants were randomly assigned to two groups: a cognitive remediation intervention group and a non-intervention control group. The control group was provided with conventional drug therapy and either day care or occupational therapy. The intervention group was provided with the “neuropsychological educational approach to cognitive remediation” developed by Medalia and co-workers. We assessed cognitive functions using the brief assessment of cognition in schizophrenia (BACS), and evaluated social and daily living functions using the global assessment of functioning (GAF) scale. Significant group by time interaction effects indicated that verbal memory, working memory, attention, and executive function showed significantly greater improvement at post-intervention for the intervention group than the control group. Social and daily living function also improved in the intervention group and improvements were maintained one year after intervention. These preliminary findings indicate that the combination of cognitive remediation and psychiatric rehabilitation is effective for facilitating improvements in cognitive function and social and daily living functions in individuals with schizophrenia.  相似文献   
95.
96.
Objective: Pregnancy hypertension is the most common gestational complication and poses a critical risk for mother and fetus. Whether environmental factors may play an important role in disease occurrence is not fully determined. Methods: To investigate the effects of prenatal manganese (Mn) exposure on gestational blood pressure, 386 women were examined. Results: Early pregnancy blood Mn was significantly (p < 0.05) correlated with blood pressure through gestation. A significant association between odds of pre-hypertension with blood Mn was shown (OR:1.150, 95% CI:1.052–1.258). Conclusion: The current study results might suggest the blood Mn level during early stage of pregnancy as a potential risk factor for increasing the risk of gestational blood pressure.  相似文献   
97.

Background

The present study aimed to obtain information enabling optimisation of the clinical effect of mizoribine (MZR) in pediatric patients with kidney disease.

Methods

A total of 105 pediatric patients with kidney disease treated at our institutions were enrolled. Kidney transplant patients were excluded. Population pharmacokinetic analysis of MZR was performed based on serum concentration data. Area under the curve from time zero to infinity (AUC) and maximal concentration (C max) were calculated by Bayesian analysis.

Results

In children, the appearance of MZR in the blood tended to be slower and the subsequent rise in blood concentration tended to be more sluggish, compared to healthy adults. Apparent volume of distribution and oral clearance were also higher in children compared to adults. A significant positive correlation was observed between patient age and AUC. There were significant differences of AUC and C max by age group. No relationship was observed between the administration method of MZR and serum concentration.

Conclusion

The pharmacokinetics of MZR was different in children compared to adults. To obtain the expected clinical efficacy, the regular MZR dosage schedule (2–3 mg/kg/day) might be insufficient for pediatric patients. In particular, younger patients might require a higher dosage of MZR per unit body weight.
  相似文献   
98.
Breast cancer resistance protein (BCRP) transporter is an efflux transporter that utilizes energy from adenosine triphosphate hydrolysis to push its substrates, regardless of the concentration gradient. Its presence on the apical membrane of the intestinal mucosa is a major obstacle for the intestinal absorption of its substrates. In this study, we examined the effects of various pharmaceutical excipients on the intestinal transport and absorption of sulfasalazine, a BCRP substrate. Four excipients, including 0.05% and 0.075% BL-9EX, 0.01% and 0.05% Brij 97, 0.075% Labrasol, and 0.05% and 0.1% Tween 20 decreased the secretory transport of sulfasalazine in an in vitro diffusion chamber. Further investigation in an in situ closed loop experiment in rats showed that 0.05% and 0.1% BL-9EX and 0.1% Brij 97 effectively enhanced the intestinal absorption of sulfasalazine while maintaining minimal toxicity to the intestinal mucosa. However, 0.1% Brij 97 also increased the intestinal absorption of 5(6)-carboxyfluorescein, a paracellular marker compound. These findings suggest that BL-9EX might effectively inhibit the BCRP-mediated efflux of sulfasalazine in vivo, indicating that BL-9EX could improve the intestinal absorption of sulfasalazine and other BCRP substrates.  相似文献   
99.
Although l ‐tryptophan is nutritionally important and widely used in medical applications, toxicity data for its oral administration are limited. The purpose of this study was to evaluate the potential toxicity of an experimental diet containing added l ‐tryptophan at doses of 0 (basal diet), 1.25%, 2.5% and 5.0% when administered to Sprague–Dawley rats for 13 weeks. There were no toxicological changes in clinical signs, ophthalmology, urinalysis, hematology, necropsy, organ weight and histopathology between control rats and those fed additional l ‐tryptophan. Body weight gain and food consumption significantly decreased throughout the administration period in males in the 2.5% group and in both sexes in the 5.0% group. At the end of the dosing period, decreases in water intake in males in the 5.0% group and in serum glucose in females in the 5.0% group were observed. The changes described above were considered toxicologically significant; however, they were not observed after a 5 week recovery period, suggesting reversibility. Consequently, the no‐observed‐adverse‐effect level of l ‐tryptophan in the present study was 1.25% for males and 2.5% for females (mean intake of l ‐tryptophan: 779 mg kg–1 body weight day–1 [males] and 1765 mg kg–1 body weight day–1 [females]). As the basal diet used in this study contained 0.27% of proteinaceous l ‐tryptophan, the no‐observed‐adverse‐effect level of overall l ‐tryptophan was 1.52% for males and 2.77% for females (mean intake of overall l ‐tryptophan: 948 mg kg–1 body weight day–1 (males) and 1956 mg kg–1 body weight day–1 (females)). We conclude that l ‐tryptophan has a low toxicity profile in terms of human use.  相似文献   
100.
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