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   21509篇
  免费   2145篇
  国内免费   476篇
耳鼻咽喉   197篇
儿科学   358篇
妇产科学   216篇
基础医学   2273篇
口腔科学   448篇
临床医学   2746篇
内科学   2852篇
皮肤病学   156篇
神经病学   1782篇
特种医学   1486篇
外国民族医学   4篇
外科学   1867篇
综合类   2488篇
现状与发展   1篇
一般理论   2篇
预防医学   2273篇
眼科学   437篇
药学   2453篇
  39篇
中国医学   1066篇
肿瘤学   986篇
  2024年   82篇
  2023年   383篇
  2022年   653篇
  2021年   1000篇
  2020年   958篇
  2019年   909篇
  2018年   946篇
  2017年   918篇
  2016年   783篇
  2015年   849篇
  2014年   1508篇
  2013年   1476篇
  2012年   1265篇
  2011年   1370篇
  2010年   1164篇
  2009年   983篇
  2008年   949篇
  2007年   951篇
  2006年   905篇
  2005年   689篇
  2004年   624篇
  2003年   544篇
  2002年   492篇
  2001年   322篇
  2000年   297篇
  1999年   297篇
  1998年   229篇
  1997年   201篇
  1996年   192篇
  1995年   176篇
  1994年   184篇
  1993年   135篇
  1992年   140篇
  1991年   140篇
  1990年   144篇
  1989年   133篇
  1988年   122篇
  1987年   99篇
  1986年   95篇
  1985年   120篇
  1984年   112篇
  1983年   100篇
  1982年   84篇
  1981年   95篇
  1980年   77篇
  1979年   48篇
  1978年   34篇
  1977年   31篇
  1976年   34篇
  1973年   18篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
51.
The present study was performed to characterize cardiovascular responses to isoprenaline and the influence of autonomic reflexes on these reponses. Nine healthy volunteers received infusions and bolus injections of isoprenaline before and after ‘autonomic blockade’ produced by intravenous atropine 0.04 mg kg-1 and clonidine 300 μg. Heart rate, blood pressures, systolic time intervals and various echocardiographic measures of cardiac contractility were registered. No significant differences in responsiveness to isoprenaline were seen when infusions were repeated on the same day without ‘autonomic blockade’. After ‘blockade’, Δ responses at 1 nmol 1-1 isoprenaline (infusions) were increased for diastolic blood pressure and decreased for systolic blood pressure and stroke volume. Bolus injections of 2 μg isoprenaline caused enhanced Δ responses after ‘autonomic blockade’ of diastolic blood pressure, left ventricular diameter in systole, ventricular circumferential fibre shortening, mean posterior wall velocity (Vmean pw), stroke volume, systemic vascular resistance, electromechanical systole (QS2) and pre-ejection period. Systolic blood pressure decreased, in contrast to a small increase without ‘blockade’. These findings are explained by differences in haemodynamic effects of isoprenaline and by the dependence of responses on reflexes when isoprenaline is administered in different ways. When heart rate was increased by bolus doses of atropine, in the presence of β-blockade (propranolol), pre-ejection period and left ventricular diameter in systole were unaffected, and Vmean pw and ventricular circumferential fibre shortening showed only small increases (compared with alterations induced by isoprenaline). However, left ventricular ejection time, QS2 and ejection time (by echocardiography), were markedly dependent on heart rate alterations. Thus, pre-ejection period, left ventricular diameter in systole Vmean pw and ventricular circumferential fibre shortening are parameters which can be useful in order to evaluate cardiac β-adrenoceptor sensitivity in vivo in man.  相似文献   
52.
Diabetes is the seventh leading cause of death in United States. Dietary intake and behaviors are essential components of diabetes management. Growing evidence suggests dietary components beyond carbohydrates may critically impact glycemic control. Assessment tools on mobile platforms have the ability to capture multiple aspects of dietary behavior in real-time throughout the day to inform and improve diabetes management and insulin dosing. The objective of this narrative review was to summarize evidence related to dietary behaviors and composition to inform a mobile image-based dietary assessment tool for managing glycemic control of both diabetes types (type 1 and type 2 diabetes). This review investigated the following topics amongst those with diabetes: (1) the role of time of eating occasion on indicators of glycemic control; and (2) the role of macronutrient composition of meals on indicators of glycemic control. A search for articles published after 2000 was completed in PubMed with the following sets of keywords “diabetes/diabetes management/diabetes prevention/diabetes risk”, “dietary behavior/eating patterns/temporal/meal timing/meal frequency”, and “macronutrient composition/glycemic index”. Results showed eating behaviors and meal macronutrient composition may affect glycemic control. Specifically, breakfast skipping, late eating and frequent meal consumption might be associated with poor glycemic control while macronutrient composition and order of the meal could also affect glycemic control. These factors should be considered in designing a dietary assessment tool, which may optimize diabetes management to reduce the burden of this disease.  相似文献   
53.
讨论了基于HART协议智能设备的实时管理系统,介绍了HART协议的基本规范,以及如何利用已有集散控制系统(DCS)和工厂信息网络的集成实现实时信息共享,取得了良好的实际效果。  相似文献   
54.
建立了蠕变局部损伤法模型,并给出单元进入损伤态的判据和失效的临界拉伸应变条件,局部蠕变损伤理论的实质就是试样是多种不同蠕变性能材料的统一,并由蠕变应力再分布得到证实,应用有限元对双缺口圆试样作了蠕变局部损伤分析,启裂时间和断裂蠕变应变值均与实验结果相吻合。  相似文献   
55.
56.
BackgroundPrevious evidence has demonstrated an exacerbating effect of increased operative time on short-term complications in total joint arthroplasty. While the same relationship may be expected for unicompartmental knee arthroplasty (UKA), supporting evidence remains sparse. The purpose of this study is to determine the impact of operative time on short-term complication rates after UKA and determine a critical threshold in operative times after which complications may increase.MethodsThe American College of Surgeons National Surgical Quality Improvement Project was queried from 2007 to 2018 to identify 11,633 UKA procedures that were included in the final analysis. The effect of operative time on complications within 30 days was evaluated using multivariate logistic regression models. Receiver operating characteristics curves and spline regression models were used to identify critical thresholds in operative time that increase the likelihood of short-term complications.ResultsLonger operative times (in minutes) were associated with higher rates of surgical site infection (90.4 ± 26.7 vs 84.8 ± 25.5, P = .003), blood transfusions (94.9 ± 28.6 vs 84.9 ± 25.5, P = .007), as well as reoperation rates (90.8 ± 27.9 vs 84.9 ± 25.5, P = .01), extended hospital length of stay (93.4 ± 29.8 vs 84.5 ± 25.2, P < .001), and mortality (110.4 ± 35.5 vs 84.9 ± 25.5, P = .008). Following multivariate logistic regression, operative time was found to independently predict increased surgical site infection, blood transfusion, myocardial infarction, extended length of stay, and mortality (odds ratio: 1.09 – 1.45, CI: 1.01 – 1.91, all P values <0.02). Receiver operating characteristics curves found an increase in mortality risk during the 30-day postoperative period after 88.5 minutes of operative time, a finding supported by spline regression plots.ConclusionThe present study found a positive correlation between increased operative times and short-term postoperative complication rates after UKA. Despite a statistically significant association with increasing operative time, odds ratios of reported complications are relatively low.  相似文献   
57.
58.
Social insurance administrative officers’ decision-making skills influence their efficiency at work and their general well-being. At work their tasks are characterised by complexity and a need for order and accountability. Moreover, cases should usually be handled and finalised within the imposed time frames. We investigated skills related to decision-making success among social insurance officers. In total, 118 administrative officers at the Swedish Social Insurance Agency (66% response rate) responded to questions on scales and measures relating to cognitive-rational, socio-emotional and time approach features of decision-making skill. In addition, they responded to questions on three scales pertaining to outcomes of everyday decisions in terms of subjective everyday difficulties, tendencies to burnout and depressive symptoms. The results showed that cognitive-rational competence was associated with lower reports of subjective everyday difficulties and depressive symptoms and thereby contributed to the explained variance in decision outcomes. Furthermore, socio-emotional and time approach features of decision-making skills contributed to the explanation for subjective everyday difficulties, tendencies to burnout and depressive symptoms. The results corroborate the basic assumption and usefulness of a broad approach in the definition and assessment of decision-making skills in human service professions in general, and of administrative officers in social insurance agencies in particular. Recommendations for future research and the implications of the results are discussed.  相似文献   
59.
60.
Summary The application of the rectal temperature time of death nomogram at the scene of death by 11 authors from 6 lego-medical institutes resulted in a standard deviation of the differences between nomographic and real death time of ± 1.3 h in 46 cases (group I) with met requirements and clearly defined points of contact, nevertheless, including 9 cases with a more progressive cooling (0.5 > Q 0.2). In cases with a real death time of more than 4 h (N = 26) the standard deviation was ± 1.0 hours corresponding to permissible variation of 95% of ± 2.0 hours. Consequently, the permissible variation of 95% was much smaller than that suggested by the nomogram. The nomographic death time interval did not agree with the real one in 5 cases out of additional 30 cases with recognizably unsure points of contact (group II).  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