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   1700473篇
  免费   118248篇
  国内免费   5264篇
耳鼻咽喉   20168篇
儿科学   55088篇
妇产科学   43057篇
基础医学   239808篇
口腔科学   41476篇
临床医学   162211篇
内科学   329665篇
皮肤病学   29917篇
神经病学   146192篇
特种医学   63515篇
外国民族医学   376篇
外科学   242161篇
综合类   34087篇
现状与发展   1篇
一般理论   769篇
预防医学   148411篇
眼科学   37039篇
药学   121748篇
  12篇
中国医学   4100篇
肿瘤学   104184篇
  2021年   15402篇
  2019年   16077篇
  2018年   40720篇
  2017年   31354篇
  2016年   34756篇
  2015年   20895篇
  2014年   28640篇
  2013年   42676篇
  2012年   65344篇
  2011年   81184篇
  2010年   52503篇
  2009年   43237篇
  2008年   73762篇
  2007年   78936篇
  2006年   59985篇
  2005年   59852篇
  2004年   58077篇
  2003年   55947篇
  2002年   52260篇
  2001年   62959篇
  2000年   64351篇
  1999年   54417篇
  1998年   17330篇
  1997年   15635篇
  1996年   15040篇
  1995年   14335篇
  1994年   13211篇
  1993年   12320篇
  1992年   42714篇
  1991年   41888篇
  1990年   40449篇
  1989年   38279篇
  1988年   35474篇
  1987年   34587篇
  1986年   33030篇
  1985年   31522篇
  1984年   24113篇
  1983年   20611篇
  1982年   12936篇
  1981年   11417篇
  1979年   21439篇
  1978年   15496篇
  1977年   12621篇
  1976年   12402篇
  1975年   12541篇
  1974年   15257篇
  1973年   14823篇
  1972年   13674篇
  1971年   12670篇
  1970年   11734篇
排序方式: 共有10000条查询结果,搜索用时 16 毫秒
951.
We compared the efficacy of flecainide versus quinidine in preventing paroxysms of atrial fibrillation in a randomized open crossover study. Twenty-six patients with weekly attacks of atrial fibrillation during the last 3 months, objectified by 24-h holter monitoring or 12-lead electrocardiogram (ECG) were treated for a period of 3 months with flecainide 100 mg b.i.d. or quinidine 500 mg b.i.d. Efficacy was assessed by 24-h holter monitoring and a questionnaire at the end of each month. Dosage was adjusted to flecainide 100 mg t.i.d. or quinidine 500 mg t.i.d. if patients still had symptomatic paroxysms of atrial fibrillation according to a questionnaire or on holter monitoring. In 46% of the patients, flecainide 100 mg b.i.d. caused total abolition of supraventricular tachycardia; after dose adjustment it caused 50% total abolition. For quinidine, the figures are 16% (p less than 0.05) and 32% (NS), respectively. Side effects occurred with flecainide only after dose adjustment (23%), but on quinidine they occurred before (8%) and after dose adjustment (20%). We conclude that flecainide suppresses paroxysms of atrial fibrillation significantly more often as compared with quinidine in the lower dosage regimen. Optimal treatment dosage of flecainide is 100 mg b.i.d. After quinidine dose adjustment, the difference in efficacy is no longer significant. However, side effects necessitating discontinuation of quinidine developed in 20% of the patients as compared to none in patients treated with flecainide 100 mg b.i.d.  相似文献   
952.
953.
In a prospective study 90 patients who had confirmed abruption of the placenta were compared with a control group. Significantly more patients who had abruptio placentae were unmarried, smoked cigarettes, received no antenatal care, had coitus within the 48 hours preceding delivery, developed intrapartum hypertension and had a lower ponderal index than the controls. More patients with abruptio placentae had proteinuria and antepartum hypertension but statistical significance was not reached. In addition, the incidence of intra-uterine growth retardation was higher in these patients.  相似文献   
954.
Summary Cytosine arabinsodie (ara-C) and etoposide (VP-16) display synergy in the laboratory. Twenty-six patients participated in a phase I study of high-dose ara-C in combination with VP-16. The dose of VP-16 was held constant at 50 mg/m2 as an intermittent infusion over 33 h; escalating doses of ara-C were given as infusions during hours 9–12 and 21–24. Myelosuppression was the dose-limiting toxicity and occurred with doses considerably less than those expected from studies of the two drugs as single agents. The suggested initial doses for phase II trials with this schedule are 750 mg/m2×2 doses of ara-C and 50 mg/m2 of VP-16. Nonhematologic toxicity was minimal; therefore, further dose escalation is feasible in patients in whom myelosuppression is acceptable.Supported in part by grants from the National Cancer Institute (CA-12197 and CA-09422) and the American Cancer Society CF-85-182  相似文献   
955.
A flow-through finite-dose diffusion cell has been designed for use in transdermal drug delivery research. The diffusion cell consists of an upper donor chamber and a lower receiver compartment through which a continuous supply of fresh solvent flows. The flow is directed to an automatic fraction collector. To validate the flow-through cell, its performance was compared directly against that of a conventional single-reservoir Franz cell. Homologous alkyl p-aminobenzoates were diffused through dimethylpolysiloxane membranes, and permeability coefficients increased with increasing chain length, reaching a plateau at the butyrate ester for both types of cells. This behavior suggests a shift from membrane-controlled diffusion to boundary layer control. Permeation of the butyrate and valerate compounds was significantly faster when the flow-through cell was used, suggesting that better mixing is obtained through the flow-through cell design. Considering the advantages offered in terms of time and labor saved through its use, the flow-through cell with automatic fraction collector appears to be a viable alternative to the conventional Franz cell.  相似文献   
956.
Rat brain hippocampal slices were incubated with or without the convulsant 4-aminopyridine (4-AP). From these slices a crude mitochondrial/synaptosomal membrane fraction was prepared and analyzed for endogenous protein phosphorylation. 4-AP (10(-5) M) stimulated the phosphorylation of a 50 kDa protein by 86%. The phosphorylation of this 50 kDa protein is Ca2+/calmodulin-dependent and we suggest that this protein is the lower molecular weight subunit of Ca2+/calmodulin-dependent protein kinase II (CaMK II).  相似文献   
957.
958.
959.
960.
This research was designed to test the extent to which health education and health services administration students' perceptions of their roles as professionals matched the expectations of professional faculty. These perceptions were found to match in general. However, doubt was cast on the extent to which internships or practicums contributed to this result, since there was no change in student responses between the beginning of the junior year and end of the senior year, a period which includes fieldwork and most of the professional coursework presumed to influence professional development. Additional research is required to test this result with other student populations in other health professions and identify the point at which professional role and task definitions are amenable to change.  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