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   10182篇
  免费   800篇
  国内免费   36篇
耳鼻咽喉   118篇
儿科学   323篇
妇产科学   283篇
基础医学   1522篇
口腔科学   207篇
临床医学   1019篇
内科学   2046篇
皮肤病学   130篇
神经病学   872篇
特种医学   225篇
外科学   1171篇
综合类   274篇
一般理论   9篇
预防医学   1115篇
眼科学   187篇
药学   922篇
中国医学   28篇
肿瘤学   567篇
  2022年   90篇
  2021年   198篇
  2020年   109篇
  2019年   144篇
  2018年   171篇
  2017年   127篇
  2016年   173篇
  2015年   182篇
  2014年   209篇
  2013年   436篇
  2012年   596篇
  2011年   635篇
  2010年   347篇
  2009年   323篇
  2008年   542篇
  2007年   573篇
  2006年   553篇
  2005年   533篇
  2004年   512篇
  2003年   480篇
  2002年   515篇
  2001年   259篇
  2000年   203篇
  1999年   206篇
  1998年   101篇
  1997年   114篇
  1996年   111篇
  1995年   94篇
  1994年   74篇
  1993年   68篇
  1992年   162篇
  1991年   140篇
  1990年   124篇
  1989年   109篇
  1988年   124篇
  1987年   125篇
  1986年   114篇
  1985年   100篇
  1984年   95篇
  1983年   91篇
  1982年   77篇
  1981年   88篇
  1980年   74篇
  1979年   75篇
  1978年   61篇
  1977年   54篇
  1976年   62篇
  1974年   63篇
  1973年   55篇
  1972年   60篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
31.
Objective. The Ciba Corning 512 coagulation monitor (CC512) can be used to monitor heparin therapy by performing an activated partial thromboplastin time (APTT) at the patient’s bedside. This study was designed to compare the CC512 results to results using the laboratory system. The relative sensitivities of both systems to the effect of oral anticoagulant therapy also was investigated.Methods. Activated partial thromboplastin times were performed with both the CC512 and laboratory system on 74 specimens from patients receiving IV heparin therapy, and on 14 specimens from patients on warfarin only. Heparin assays were performed on 43 of the specimens from the heparinized patients.Results. When a patient was receiving heparin only, the APTT results of the CC512 proved to be similar to existing laboratory methods. The CC512 APTT results of patients on warfarin only were markedly prolonged, whereas the laboratory APTTs were only slightly affected.Conclusion. The CC512 results were comparable to the laboratory system. However, the CC512 APTT was more sensitive to the effect of warfarin than the laboratory APTT system used in this study. CC512 APTT results on a patient receiving both oral and intravenous anticoagulation could be misleading. The authors wish to thank D.M. O’Brien and the nursing staff of the Coronary Care Unit for providing CC512 data and laboratory specimens, and I. Smith for the preparation of graphics. We also wish to thank Australian Diagnostics Corporation, which provided consumables.  相似文献   
32.
A procedure for the detection of brodifacoum (BDF) in serum was developed. Extraction of BDF was achieved by acidification of 2 ml of serum with 1 ml of 1.5% acetic acid followed by dual extractions with 10 ml diethyl ether and ether: acetonitrile [1:1]. In spiking experiments, 68 +/- 3, 61 +/- 4 and 65 +/- 5% of added BDF was recovered from serum containing 1000, 100 and 25 ng BDF/ml, respectively. Two high performance liquid chromatography solvent systems were used for chromatographic separation (A: 1.5% acetic acid, pH 4.5: acetonitrile [1:2] with 1% dibutylamine; and B:O.2 M tris(hydroxymethyl)aminomethane, pH 7.5:acetonitrile [1:3]). Detection limits were 75 and 3 ng BDF/ml of serum using ultraviolet absorption (254 nm) and fluorescence measurement (313 nm excitation, 375 nm emission), respectively. This method has been used successfully to monitor serum concentrations of BDF in experimental and field cases of exposure.  相似文献   
33.
A bstract Objectives and Background : The purpose of this study was to document our initial experience with patients 90 years of age and older and to determine whether cardiac surgery is justified in this age group. Cardiac surgery in octogenarians has proven to be a successful and worthwhile procedure. A small group of nonagenarians with severe coronary artery disease (CAD) and aortic valve disease refractory to medical therapy have been considered for surgery. Methods : Fourteen patients aged 90 or more underwent cardiac surgery for symptomatic CAD or aortic valvular disease refractory to medical therapy. Eight patients underwent isolated coronary artery bypass grafting (CABG) and six patients underwent aortic valve replacement (AVR). All patients were in NYHA Class IV preoperatively. Results : Hospital mortality occurred in one patient (7%). Hospital morbidity occurred in 10 patients (71%) and included 7 cardiac, 5 neurological, 1 gastrointestinal, 1 infectious, and 1 pulmonary event. All survivors left the hospital symptomatically improved. The mean length of stay was 26 days. Four CABG patients went on to die at a mean of 2 years and 2 months, and 3 remain alive at a mean of 2 years and 4 months. Three AVR patients expired at a mean of 3 years and 4 months, and 3 remain alive at 4 years and 1 month. Conclusions : Cardiac surgery in carefully selected nonagenarians is justified and can be performed with acceptable results.  相似文献   
34.
35.
36.
37.
Restless legs syndrome (RLS) is one of the commonest movement disorders affecting sleep and also daytime functioning. The prevalence may be 8%–10% of the white Caucasian population. The diagnosis is simple and is based on a well-validated clinical questionnaire, yet misdiagnosis is common and the condition remains underdiagnosed and consequently inappropriately treated, often causing great distress to the sufferers. In spite of robust evidence for effective treatment of RLS, patients may often be told to “put up with the symptoms” and suffer the consequence of years of poor sleep which may lead to major lifestyle changes. This review addresses the diagnostic issues, the differential diagnosis, and the evidence base for treatment of the common condition.  相似文献   
38.
Nonmotor symptoms (NMS) of Parkinson's disease (PD) are not well recognized in clinical practice, either in primary or in secondary care, and are frequently missed during routine consultations. There is no single instrument (questionnaire or scale) that enables a comprehensive assessment of the range of NMS in PD both for the identification of problems and for the measurement of outcome. Against this background, a multidisciplinary group of experts, including patient group representatives, has developed an NMS screening questionnaire comprising 30 items. This instrument does not provide an overall score of disability and is not a graded or rating instrument. Instead, it is a screening tool designed to draw attention to the presence of NMS and initiate further investigation. In this article, we present the results from an international pilot study assessing feasibility, validity, and acceptability of a nonmotor questionnaire (NMSQuest). Data from 123 PD patients and 96 controls were analyzed. NMS were highly significantly more prevalent in PD compared to controls (PD NMS, median = 9.0, mean = 9.5 vs. control NMS, median = 5.5, mean = 4.0; Mann-Whitney, Kruskal-Wallis, and t test, P < 0.0001), with PD patients reporting at least 10 different NMS on average per patient. In PD, NMS were highly significantly more prevalent across all disease stages and the number of symptoms correlated significantly with advancing disease and duration of disease. Furthermore, frequently, problems such as diplopia, dribbling, apathy, blues, taste and smell problems were never previously disclosed to the health professionals.  相似文献   
39.
The determination of the UK Government to modernise medical careers, the shortage of training jobs for local medical graduates, the establishment of the Postgraduate Medical Training and Education Board (PMETB) and European Union rules have combined to change the scheme of surgical training in the United Kingdom. In the opinion of the author, the Indian Otorhinolaryngological (ORL) trainee can no longer aspire to reasonable higher training in the UK.  相似文献   
40.
ACUTE EFFECT OF ETHANOL ON RENAL ELECTROLYTE TRANSPORT IN THE RAT   总被引:1,自引:0,他引:1  
1. Despite human and animal studies, the direct effect of ethanol on renal water and electrolyte transport is poorly understood. The acute effect of increasing plasma concentrations of ethanol was evaluated in a water diuretic anaesthetized rat model which inhibits endogenous arginine vaso-pressin (AVP) release. 2. Ethanol at a plasma concentration of 1.69 ±0.28 mmol/L produced an immediate increase in urine flow (174 ± 11 μL/min pre-ethanol and 189 ± 13 and then 206 ± 12 μL/min during the ethanol infusion; P<0.001) as well as an increase in fractional sodium excretion (0.17 ± 0.04 to 0.28 ± 0.05 and 0.27 ± 0.05%; P<0.001). There was also a brief phosphaturia. These increases in electrolyte excretion had returned to control values by 20 min despite a further increase in the plasma ethanol concentration. 3. The urinary excretion of potassium, calcium and magnesium was not altered nor was glomerular filtration rate or renal plasma flow. 4. Ethanol at a mean concentration of 1.60 mmol/L did not alter the action of a maximal concentration of AVP (75 ng/kg) on water or electrolyte transport. However, the antidiuretic effect of a submaximal concentration of AVP (7.5 ng/kg) was augmented by ethanol at concentrations of 1.63 and 0.98 mmol/L. 5. These studies suggest that the ethanol induced diuresis commonly ascribed to inhibition of AVP secretion may also be due to other intrarenal effects of ethanol, possibly acting within the proximal tubule. These results also confirm recent in vitro findings that while ethanol does not inhibit the action of a maximal concentration of AVP, it does modulate the effects of lower AVP concentrations.  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