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   6418篇
  免费   452篇
  国内免费   22篇
耳鼻咽喉   128篇
儿科学   300篇
妇产科学   201篇
基础医学   887篇
口腔科学   80篇
临床医学   520篇
内科学   1307篇
皮肤病学   137篇
神经病学   584篇
特种医学   277篇
外科学   876篇
综合类   107篇
一般理论   4篇
预防医学   564篇
眼科学   100篇
药学   286篇
肿瘤学   534篇
  2021年   90篇
  2019年   66篇
  2018年   79篇
  2017年   75篇
  2016年   80篇
  2015年   79篇
  2014年   131篇
  2013年   203篇
  2012年   260篇
  2011年   278篇
  2010年   161篇
  2009年   138篇
  2008年   254篇
  2007年   243篇
  2006年   243篇
  2005年   226篇
  2004年   230篇
  2003年   222篇
  2002年   203篇
  2001年   179篇
  2000年   165篇
  1999年   185篇
  1998年   74篇
  1997年   71篇
  1996年   83篇
  1995年   64篇
  1994年   58篇
  1993年   51篇
  1992年   182篇
  1991年   149篇
  1990年   136篇
  1989年   145篇
  1988年   135篇
  1987年   158篇
  1986年   136篇
  1985年   142篇
  1984年   115篇
  1983年   114篇
  1982年   77篇
  1981年   62篇
  1980年   68篇
  1979年   99篇
  1978年   73篇
  1977年   55篇
  1976年   59篇
  1974年   70篇
  1973年   71篇
  1972年   60篇
  1971年   77篇
  1970年   54篇
排序方式: 共有6892条查询结果,搜索用时 15 毫秒
1.
2.
PURPOSE: Epidermal growth factor receptor is expressed in pediatric malignant solid tumors. We conducted a phase I trial of gefitinib, an epidermal growth factor receptor tyrosine kinase inhibitor, in children with refractory solid tumors. PATIENTS AND METHODS: Gefitinib (150, 300, 400, or 500 mg/m2) was administered orally to cohorts of three to six patients once daily continuously until disease progression or significant toxicity. Pharmacokinetic studies were performed during course one (day 1 through 28). RESULTS: Of the 25 enrolled patients, 19 (median age, 15 years) were fully evaluable for toxicity and received 54 courses. Dose-limiting toxicity was rash in two patients treated with 500 mg/m2 and elevated ALT and AST in one patient treated with 400 mg/m2. The maximum-tolerated dose was 400 mg/m2/d. The most frequent non-dose-limiting toxicities were grade 1 or 2 dry skin, anemia, diarrhea, nausea, and vomiting. One patient with Ewing's sarcoma had a partial response. Disease stabilized for 8 to > or = 60 weeks in two patients with Wilms' tumor and two with brainstem glioma (one exophytic). At 400 mg/m2, the median peak gefitinib plasma concentration was 2.2 microg/mL (range, 1.2 to 3.6 microg/mL) and occurred at a median of 2.3 hours (range, 2.0 to 8.3 hours) after drug administration. The median apparent clearance and median half-life were 14.8 L/h/m2 (range, 3.8 to 24.8 L/h/m2) and 11.7 hours (range, 5.6 to 22.8 hours), respectively. Gefitinib systemic exposures were comparable with those associated with antitumor activity in adults. CONCLUSION: Oral gefitinib is well tolerated in children. Development of the drug in combination with cytotoxic chemotherapy will be pursued.  相似文献   
3.
4.
The cytochrome P450 mono-oxygenase gene, CYP2D6 on chromosome 22q13 (ch22q13), has been inconsistently associated with Parkinson's disease. Associations with CYP2D6 have either been absent altogether or have involved more than one polymorphism, many of which have the same metabolic effect on gene expression. We examined the association between CYP2D6 polymorphisms and Parkinson's disease in a case-control study and included 10 polymorphic dinucleotide repeat markers linked to CYP2D6 to determine whether the association was present or due to linkage disequilibrium. There was no association between any polymorphism of CYP2D6 and Parkinson's disease, but two of 10 dinucleotide repeat markers linked to CYP2D6 were associated with the disease. These results provide evidence to suggest that there may be an unidentified locus for susceptibility to Parkinson's disease that is in linkage disequilibrium with dinucleotide repeat markers mapping near CYP2D6 on ch22q13.  相似文献   
5.
Tissue distribution studies, utilizing whole-body autoradiography and organ dissection techniques, were conducted in male Fischer 344 rats following the oral administration of 14C-dapoxetine HCl, a potent serotonin reuptake inhibitor. The preliminary study using whole-body autoradiography proved invaluable in locating radioactivity in an organ not usually harvested in a tissue distribution study, namely the preputial gland. Selected organs, based on whole-body autoradiography findings, were dissected from rats and analyzed for radiocarbon content by liquid scintillation counting and for parent drug and N-dealkylated metabolites by extraction and HPLC analysis. Highest concentrations of radiocarbon were observed in the organs of absorption and elimination (ileum, cecum, stomach, duodenum, liver, colon, and kidney) but notable quantities were observed in the lung and preputial and Harderian glands. Most tissues had returned to background radioactive levels 72 h after dosing but persistent concentrations of radiocarbon were present in the preputial gland and liver one week after the single dose of 14C-dapoxetine. Analysis by HPLC demonstrated the presence of parent drug and N-desmethyl metabolite (nor-dapoxetine) in those organs examined; however, the majority of the radioactivity remained unidentified.  相似文献   
6.
用体外培养的人的伪表皮作为模型,进行药物毒理学作用的研究,观察了二甲亚砜(DMSO)在不同浓度和不同接触时间条件下,对人的伪表皮细胞脱氧核糖核酸(DNA)、核糖核酸(RNA)和蛋白质合成的影响:随着接触时间的延长,DNA、RNA和蛋白质合成均受抑制。低浓度条件下(1%),DNA、RNA和蛋白质合成增加;在15~50%浓度下,DNA和蛋白质合成抑制,而RNA合成仍增加;在高浓度条件下(70%~100%),DNA、RNA和蛋白质合成均明显抑制。  相似文献   
7.
A stratified sample of normal infants born at term at Johannesburg Hospital, who attended the hospital for a routine 6-week follow-up visit, were selected to include 43 infants who were exclusively breast-fed, 42 fed a low-sodium formula and 39 fed a high-sodium formula (greater than 10 mmol sodium/l). Dynamic skinfold thickness measurements (DSTM), designed to assess the amount of interstitial fluid, were performed on each infant by the application of a skinfold caliper for a 3-second sampling period at two sites. The curves generated by these applications were recorded and analysed by microcomputer. There were no differences between any of the feeding groups for DSTM measurements of blood pressure suggesting that the range of sodium ingested by these groups of infants had no significant effects on extracellular water content. However, using multiple linear regression, both DSTM and blood pressure were best predicted by body weight and not by age or any other anthropometric measurement. Thus the normal postnatal decrease in extracellular fluid volume and increase in blood pressure appears to be most closely related to an increase in body weight.  相似文献   
8.
Preliminary evaluation of 2 related computer-based speech training and practice aids for profoundly deaf children was conducted. The Speech Training Station (STS) uses both acoustic and physiological transducters for assessment and training in a school of clinic. The Speech Practice Station (SPS) uses the acoustic signal, and was designed primarily for use in the home. A series of games and activities was implemented on the 2 systems. Use of the STS was evaluated by 2 speech clinicians during a 15-month period. Fifteen children were subjects in the evaluation. The aid was found to be easily incorporated into clinic activities and useful for diagnosis and therapy. The SPS was evaluated during a 1-to-2-week period, during which it was placed in the homes of 5 profoundly deaf children. Using an activity log and questionnaire completed by the childrens' parents, usage statistics and impressions were obtained. Potential value and problems with such aids are discussed.  相似文献   
9.
Major depressive disorder is a psychiatric disorder that encompasses a broad range of emotional, psychological, behavioral, and physical symptoms (Fava et al., 2004). The nurse in the hospital, office, school, or community setting can provide the essential elements of effective care for depression, including early detection by screening, medication teaching, depression education, teaching coping skills, and appropriate use of specialists and resources. Utilizing the nursing process, the nurse can provide comprehensive care to improve the depressed patient's physical and psychological well-being.  相似文献   
10.
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