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   1489篇
  免费   94篇
  国内免费   8篇
耳鼻咽喉   23篇
儿科学   48篇
妇产科学   34篇
基础医学   231篇
口腔科学   23篇
临床医学   148篇
内科学   266篇
皮肤病学   32篇
神经病学   105篇
特种医学   127篇
外科学   208篇
综合类   13篇
预防医学   90篇
眼科学   15篇
药学   116篇
中国医学   19篇
肿瘤学   93篇
  2023年   14篇
  2022年   19篇
  2021年   40篇
  2020年   29篇
  2019年   28篇
  2018年   43篇
  2017年   24篇
  2016年   39篇
  2015年   38篇
  2014年   51篇
  2013年   64篇
  2012年   83篇
  2011年   99篇
  2010年   70篇
  2009年   52篇
  2008年   92篇
  2007年   82篇
  2006年   79篇
  2005年   49篇
  2004年   57篇
  2003年   62篇
  2002年   45篇
  2001年   28篇
  2000年   29篇
  1999年   17篇
  1998年   25篇
  1997年   29篇
  1996年   22篇
  1995年   18篇
  1994年   15篇
  1993年   16篇
  1992年   25篇
  1991年   6篇
  1990年   11篇
  1989年   16篇
  1988年   17篇
  1987年   12篇
  1986年   15篇
  1985年   16篇
  1984年   10篇
  1983年   6篇
  1982年   8篇
  1980年   9篇
  1979年   8篇
  1978年   7篇
  1977年   10篇
  1976年   10篇
  1975年   11篇
  1973年   8篇
  1967年   4篇
排序方式: 共有1591条查询结果,搜索用时 0 毫秒
1.
BACKGROUND AND PURPOSE: Marine luminous bacteria were isolated and identified from samples in shallow coastal waters of Taiwan during the relatively warm seasons. METHODS: Identification of the luminous isolates was performed based on differences of phenotypic and genotypic characteristics together with data from phylogenetic analysis. RESULTS: Twenty seven strains of marine luminous bacteria were isolated. They were divided into five types based on differences of phenotypic characteristics. However, they could be clustered into only two genotypes according to the analysis of restriction patterns of polymerase chain reaction-amplified 16S rRNA genes digested with various restriction enzymes. The characterization data together with the 16S rRNA gene-based phylogenetic analysis revealed that the isolates included in phenotype I (seven isolates) could be Photobacterium leiognathi, and those included in phenotypes II-V (twenty isolates) might be classified as Vibrio harveyi. However, phylogeny based on gyrB sequences indicated that phenotypes II-V could be classified into two species, V. harveyi and Vibrio campbellii. CONCLUSION: Culturable luminous bacteria in the shallow coastal waters of Taiwan during the sampling period are dominated by V. harveyi/campbellii and P. leiognathi, and the former species appeared to be more prevalent and numerous than the latter species in general.  相似文献   
2.
Background and Aims: Primary biliary cirrhosis (PBC) might be complicated by osteoporosis, whose etiology remains unknown but seems to be multifactorial. Prevalence rates of 30% to 60% for distal renal tubular acidosis (DRTA) have been reported in PBC patients, generally as incomplete DRTA. Although it is undisputed that a reduced bone mineral density (BMD) is the expected outcome among patients who have been suffering from longstanding chronic metabolic acidosis, it is unclear if incomplete DRTA is also associated with metabolic bone disease in PBC patients. The present study was undertaken to compare the BMD of PBC patients with and without DRTA.
Methods: The BMD of 23 PBC patients (11 with DRTA and 12 without), all with normal clearance of creatinine, was assessed by dual energy radiograph absorptiometry. The diagnosis of DRTA was made if the urine pH was above 5.4 in all samples after the oral acid overload, showing tubular inability to acidify urine in the presence of test-induced systemic metabolic acidosis.
Results: Densitometric signs of osteoporosis were found in 82% of DRTA cases and in 83% of patients without DRTA (difference not significant). There were no significant differences in BMD measurement, T and Z scores of patients with and without DRTA.
Conclusions: The present study could not support a correlation between the presence of DRTA and the bone loss observed in PBC patients.  相似文献   
3.
4.
We report a cast of ossifying fibroma of the nose, arising from the bony septum and extending into the nasophaynx in a 2 yrs. old child presenting with features of obstructed nose.  相似文献   
5.
6.
Summary— In the present study we have compared the steady state biopharmaceutic characteristics of four diltiazem once daily controlled release capsules: Mono-Tildiem LP 300® (300 mg), Adizem® XL (300 mg)1, Cardizem® (300 mg) and Dilacor® (240 mg). Sixteen healthy male volunteers (aged 22.9 ± 3.3 years, range 19–31 years) completed an open label, multiple oral dose, randomized, four-period crossover study without a washout period in between. The volunteers received each diltiazem formulation once daily for four days. Trough diltiazem and metabolites plasma concentrations were determined on days 3 and 4. The 24-h plasma concentration-time profiles were assessed after the dose on day 4 of each period. The following steady state pharmacokinetic parameters for diltiazem were calculated: the minimum plasma concentration (cmin), the maximum plasma concentration (cmax), the time to reach that concentration (tmax), the time interval during which the plasma concentration exceeds 50% of cmax (t50), the area under the plasma concentration-time curve (AUC72–96) and the peak-to-trough fluctuation (PTF). For the metabolites of diltiazem, N-mono-desmethyl-diltiazem (NDM) and desacetyldiltiazem (DAD), AUC72–96 (AUCNDM and AUCDAD) and the ratio metabolite/parent compound were calculated. Steady state was achieved on day 3. Except one, all controlled release formulations have satisfactory controlled release properties allowing once daily administration. However, significant (P < 0.05) differences were found between the pharmacokinetic characteristics which do not allow exchange of the various formulations. Concentrations well below 50 ng·mL-1 in the morning hours were observed for Dilacor® (240 mg) and Adizem® XL (300 mg), which could be a disadvantage of these formulations as it is well-known that ischaemic events occur at a higher rate during that part of the day. The plasma concentration profiles of NDM and DAD, the major circulating metabolites, parallel the plasma concentration profiles for the parent compound. From a clinical point of view, all treatments were well tolerated.  相似文献   
7.
8.
Steroids are usually identified as genomic regulators, yet recently a body of evidence has accumulated demonstrating specific plasma membrane effects, as well as coordinative effects, of some steroids on both membrane and intracellular receptors. The resulting rapid (<1 min) modulation of cellular activity has strongly suggested a non-genomic, and possibly modulatory, role for certain steroid compounds, and dramatic effects on membranes of excitable as well as other tissues have been demonstrated. Steroid synthesis and metabolism have been shown to exist in the CNS, and the effects have been seen in both the central and peripheral nervous systems. The major groups of neuroactive steroids, and their metabolites, have been progesterone, deoxycorticosterone, and some androgens, notably dihydroxyepiandrosterone (DHEA). These compounds show increased concentrations both in blood and in the brain following stress and they have also been associated with anxiolytic effects and antiepileptic activity. In the periphery, some of these compounds show remarkable inhibitory effects on the secretion of catecholamines and other neurotransmitters. The mechanism for the majority of the effects of these steroids is via their effect on receptor-mediated binding to ligand-gated ion channels. Activation of the GABAA receptor complex, resulting in the opening of its central chloride channel, is the major target of the neuroactive steroids, resulting in re-polarization of the plasma membrane and inhibition of further neuronal firing. The anxiolytic, anti-convulsant and sedative-hypnotic actions of these neuroactive steroids have resulted in their being used as therapeutic agents for the treatment of anxiety, epilepsy, insomnia, and possibly for the alteration of pain thresholds.  相似文献   
9.
Five unrelated patients (a male and 4 females) were affected with a previously undefined multiple congenital anomalies/mental retardation syndrome which has been designated the facio-cutaneous-skeletal (FCS) syndrome and which includes mental retardation with specific sociable, humorous behavior, characteristic facial appearance, excessive generalized skin, postnatal growth failure, and skeletal involvement. Consanguinity was noted in 2 patients, thus autosomal recessive inheritance is suggested. © 1992 Wiley-Liss, Inc.  相似文献   
10.
A diagnosis of the Neu-Laxova syndrome (NLS) was made by ultrasonography at 32 wks of gestation. Ultrasonographic examination showed intrauterine growth retardation (IUGR), Dandy-Walker anomaly, choroid plexus cysts, receding forehead and microcephaly, bilateral cataract without prominent eyes, scalp edema with no generalized edema, retrognathia, curved penis, and flexion deformities of limbs. The findings in this case are consistent with NLS; however, they did not fit any of Curry's [1982] groups. Massive swelling of hands and feet were among the main manifestations in classic NLS cases. In the case presented herein, edema was noted only in the scalp. This might shed further light on the question of variability vs. heterogeneity in the NLS. This case shows the existing possibility of an early diagnosis of NLS and adds Dandy-Walker anomaly and choroid plexus cysts as new findings to this syndrome. © 1992 Wiley-Liss, Inc.  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