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   18563篇
  免费   1179篇
  国内免费   81篇
耳鼻咽喉   172篇
儿科学   482篇
妇产科学   383篇
基础医学   2117篇
口腔科学   322篇
临床医学   1523篇
内科学   3915篇
皮肤病学   225篇
神经病学   1023篇
特种医学   526篇
外科学   3299篇
综合类   639篇
一般理论   18篇
预防医学   1426篇
眼科学   506篇
药学   1836篇
中国医学   218篇
肿瘤学   1193篇
  2023年   169篇
  2022年   515篇
  2021年   652篇
  2020年   423篇
  2019年   528篇
  2018年   637篇
  2017年   444篇
  2016年   360篇
  2015年   499篇
  2014年   690篇
  2013年   863篇
  2012年   1287篇
  2011年   1266篇
  2010年   735篇
  2009年   560篇
  2008年   995篇
  2007年   984篇
  2006年   915篇
  2005年   840篇
  2004年   771篇
  2003年   691篇
  2002年   580篇
  2001年   545篇
  2000年   488篇
  1999年   389篇
  1998年   143篇
  1997年   113篇
  1996年   107篇
  1995年   115篇
  1994年   60篇
  1993年   75篇
  1992年   202篇
  1991年   186篇
  1990年   165篇
  1989年   170篇
  1988年   134篇
  1987年   152篇
  1986年   123篇
  1985年   134篇
  1984年   110篇
  1983年   86篇
  1982年   59篇
  1981年   60篇
  1979年   97篇
  1978年   64篇
  1977年   66篇
  1975年   60篇
  1974年   51篇
  1973年   54篇
  1972年   50篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
981.
Comparison of hamycin with trichomycin   总被引:2,自引:0,他引:2  
  相似文献   
982.
983.
984.
985.
Hearing impairment has been associated with cognitive deficits. It is not yet clear whether cochlear implants enable children to reduce or overcome these deficits. This study examined whether hearing impaired children with cochlear implants differed from hearing impaired children without cochlear implants or from hearing children. The three age-matched groups were compared on a non-verbal measure of cognition, the Leiter International Performance Scale-Revised (LIPS-R), and a measure of behaviour, the Child Behaviour Checklist (CBCL). Apart from their scores on the Attention Sustained Subtest of the LIPS-R, the performance of the implanted group and the hearing group closely corresponded, while the hearing impaired children without cochlear implants performed below the level achieved by both these groups. There were no differences between any groups on the CBCL. It was concluded that hearing impaired children with cochlear implants were able to perform at the same non-verbal cognitive level as hearing children.  相似文献   
986.
We synthesized and assessed the role of a diacylglycerol (DAG)-containing docosahexaenoic acid (DHA), that is, 1-stearoyl-2-docosahexaenoyl-sn-glycerol (SDHG), in the contraction of guinea pig airway smooth muscle (ASM). We compared its action with 1-stearoyl-2-arachidonoyl-sn-glycerol (SAG) and 1,2-dioctanoyl-sn-glycerol (1,2-DiC8), a stable DAG analog. The three DAGs (SAG, SDHG, and 1,2-DiC8) induced reversible concentration-dependent contraction of ASM. SDHG induced higher guinea pig ASM contraction than did SAG and 1,2-DiC8. The effects of SDHG were blocked, to different extents, by nifedipine (L-type Ca2+ channel blocker). By employing GF-109203X (protein kinase C [PKC] inhibitor) and lanthanum (La3+), a nonselective cation channel blocker, we observed that SDHG evoked ASM contractile response via PKC-dependent and PKC-independent (but Ca2+-dependent) pathways. Interestingly, SAG exerted its action only by increasing [Ca2+]i and did not require PKC activation. To probe the implication of calcium mobilization, we employed thapsigargin (TG), which also induced ASM contraction in a calcium-dependent manner. SDHG and 1,2-DiC8, in a PKC-dependent manner, induced the phosphorylation of CPI-17 (myosin light chain phosphatase inhibitor of 17 kD). Furthermore, SAG and TG failed to phosphorylate CPI-17 in ASM cells. Our results suggest that different DAG species, produced during a dietary supplementation with fatty acids, could modulate the reactivity of airway smooth muscles in a PKC-dependent and -independent manner, and hence, may play a critical role in health and disease.  相似文献   
987.
Levy PY  Khan M  Raoult D 《The New England journal of medicine》2005,352(11):1154-5; author reply 1154-5
  相似文献   
988.
There is a close inter-relationship between oxidative stress, coagulation, inflammation, and smooth muscle cell growth as key components of atherosclerosis (Fig. 1). As an analgesic and anti-pyretic, aspirin has been in use for over a century. It acetylates the COX enzyme, irreversibly inhibiting the formation of prostaglandin. Its action on platelet TxA2 has highlighted its role as an anti-thrombotic agent in cardiovascular patients. Over the last two decades, unique anti-inflammatory properties of aspirin not shared by other non-steroidals have been discovered. Aspirin biotransforms into salicylate, which has diverse but potent anti-inflammatory properties. As we strive to better understand the concepts of atherogenesis, chronic inflammation, oxidative stress, and endothelial activation, these novel effects of aspirin provide new insights as to how this wonder drug works. These effects of aspirin alter many, if not all, components of the atherogenesis cascade shown in Fig. 1.  相似文献   
989.
INTRODUCTION: Doppler ultrasound (DUS) is used as a screening tool to assess internal carotid artery (ICA) disease. Recent reports suggest that the DUS may be inaccurate in over 28% of patients. We sought to evaluate the accuracy of DUS, when performed in a dedicated stroke prevention clinic (SPC). METHODS: We retrospectively reviewed the charts of patients who had a DUS performed in our SPC, followed by conventional cerebral angiography. Three groups of patients were defined. Group 1 had DUS measured ICA stenosis of >50%; Group II had a DUS measured ICA stenosis of <50%; Group III had complete ICA occlusion on DUS. RESULTS: Sixty-seven patients (69 arteries) were included in the study. There were 45 patients in Group I and based on the findings of cerebral angiography, carotid endarterectomy was considered inappropriate in only one patient--a misclassification rate of 2.2% (95% CI: 0 - 6.5%). Group II consisted of 19 patients and on cerebral angiography, none of these patients had a stenosis of >50%--a misclassification rate of 0%. Group III consisted of five patients in whom DUS showed complete ICA occlusion. The angiogram confirmed the occlusion in all five patients--a misclassification rate of 0%. Overall, misclassification rate was 1.45% (95% CI: 0 - 4.3%). CONCLUSIONS: Doppler ultrasound when performed in a stroke prevention clinic (SPC), has a high accuracy in measuring ICA stenosis of >50%. Doppler ultrasound is reliable in detecting complete ICA occlusion and finally DUS is a reliable screening tool to rule out clinically significant ICA stenosis.  相似文献   
990.
PURPOSE: To estimate the incidence and long-term outcome of brain tumor related seizures in children and to identify risk factors for adverse seizure outcome. METHODS: Analysis of medical records of children treated for brain tumor and seizures in a single institution. Children were identified from hospital database and neurology clinic records. Seizure status was characterized for the 6 months prior to most recent follow-up. RESULTS: Median follow-up after first seizure of the 157 analyzed children was 3.3 years. Tumor location was supratentorial in 81% and posterior fossa in 19%. Initial anti-epileptic drugs were phenytoin (n=52), carbamazepine (n=38), phenobarbital (n=14), gabapentin (n=31), or others (n=22). Seizures were controlled in 65% of the children and uncontrolled in 35% (17% intractable). Gabapentin showed a trend toward better seizure control (p=0.06). Neurologic deficit, T2 peri-cavity hyperintensity, and EEG slow waves were independently predictive of uncontrolled seizures by multivariate analysis. CONCLUSIONS: T2 peri-cavity hyperintensity, focal neurologic deficits, and EEG slow waves predict poor seizure control in children with brain tumors. Seizures can be controlled in most patients with brain tumors. Gabapentin use as first anti-epileptic drug needs to be studied prospectively.  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