全文获取类型
收费全文 | 1099篇 |
免费 | 175篇 |
国内免费 | 48篇 |
出版年
2023年 | 32篇 |
2022年 | 33篇 |
2021年 | 50篇 |
2020年 | 42篇 |
2019年 | 51篇 |
2018年 | 56篇 |
2017年 | 38篇 |
2016年 | 34篇 |
2015年 | 35篇 |
2014年 | 72篇 |
2013年 | 65篇 |
2012年 | 39篇 |
2011年 | 42篇 |
2010年 | 30篇 |
2009年 | 31篇 |
2008年 | 46篇 |
2007年 | 53篇 |
2006年 | 33篇 |
2005年 | 42篇 |
2004年 | 33篇 |
2003年 | 36篇 |
2002年 | 37篇 |
2001年 | 30篇 |
2000年 | 20篇 |
1999年 | 26篇 |
1998年 | 31篇 |
1997年 | 23篇 |
1996年 | 21篇 |
1995年 | 25篇 |
1994年 | 18篇 |
1993年 | 15篇 |
1992年 | 23篇 |
1991年 | 16篇 |
1990年 | 13篇 |
1989年 | 7篇 |
1988年 | 14篇 |
1987年 | 13篇 |
1986年 | 9篇 |
1985年 | 18篇 |
1984年 | 17篇 |
1983年 | 12篇 |
1982年 | 7篇 |
1981年 | 10篇 |
1980年 | 11篇 |
1979年 | 2篇 |
1978年 | 3篇 |
1977年 | 2篇 |
1975年 | 1篇 |
1973年 | 2篇 |
1971年 | 1篇 |
排序方式: 共有1322条查询结果,搜索用时 78 毫秒
1.
目的:探究七氟醚复合瑞芬太尼对扁桃体切除术患儿苏醒期躁动及术后镇痛的影响。方法:选入我院择期行扁桃体切除术患儿39例,随机将患儿划分为实验组及对照组。对照组18例予七氟醚行吸入诱导及维持麻醉;实验组21例予七氟醚及瑞芬太尼静吸复合维持麻醉。记录两组血压心率,比较两组患儿苏醒期的躁动评分、术后镇痛、及是否发生恶心呕吐情况。结果:实验组总有效率高于对照组,差异存在统计学意义(P0.05);与对照组相比,实验组患儿的苏醒期躁动评分较低、发生率较低,镇静指数评分较高,呼吸功能恢复快、拔管时间短,差异有统计学意义(P0.05);实验组血压及心率较对照组平稳,差异有统计学意义(P0.05)。结论:七氟醚复合瑞芬太尼在进行全身麻醉时,麻醉效果良好,能够明显减少苏醒期患儿躁动的发生,降低患儿术后疼痛,并且呼吸系统恢复快,较小影响心血管系统,值得推广。 相似文献
2.
3.
4.
Dietmar B?nsch Ralph Schneider Ibrahim Akin Cristoph A. Nienaber 《Journal of visualized experiments : JoVE》2012,(60)
Implantable cardioverter-defibrillators (ICDs) terminate ventricular tachycardia (VT) and ventricular fibrillation (VF) with high efficacy and can protect patients from sudden cardiac death (SCD). However, inappropriate shocks may occur if tachycardias are misdiagnosed. Inappropriate shocks are harmful and impair patient quality of life. The risk of inappropriate therapy increases with lower detection rates programmed in the ICD. Single-chamber detection poses greater risks for misdiagnosis when compared with dual-chamber devices that have the benefit of additional atrial information. However, using a dual-chamber device merely for the sake of detection is generally not accepted, since the risks associated with the second electrode may outweigh the benefits of detection. Therefore, BIOTRONIK developed a ventricular lead called the LinoxSMART S DX, which allows for the detection of atrial signals from two electrodes positioned at the atrial part of the ventricular electrode. This device contains two ring electrodes; one that contacts the atrial wall at the junction of the superior vena cava (SVC) and one positioned at the free floating part of the electrode in the atrium. The excellent signal quality can only be achieved by a special filter setting in the ICD (Lumax 540 and 740 VR-T DX, BIOTRONIK). Here, the ease of implantation of the system will be demonstrated. 相似文献
5.
6.
7.
S. L. GLOCKLING FLS G. W. BEAKES 《Botanical journal of the Linnean Society. Linnean Society of London》2001,136(3):329-338
Two new species of Haptoglossa , one zoosporic, H. northumbrica , and one aplanosporic, H. polymorphs, , were isolated from samples of manure and horse dung in north-east England. The zoosporic H. northumbrica is morphologically similar to H. dickii but differs in having slightly smaller infection gun cells with a unique internal arrangement of cones in the apical missile chamber. The thallus of the aplanosporic H. polymorpha is similar to H. heteromorpha but produces three different types of aplanospore. The smaller cysts either develop into broad, arcuate gun cells or form curved adhesive cells that have a rounded base. These curved adhesive cells have very different internal ultrastructural organization. The large cysts develop into infection cells that are morphologically similar to the curved adhesive cells, but their internal structure has not yet been observed. 相似文献
8.
Does hydraulic lift exist in shallow-rooted species? A quantitative examination with a half-shrub Gutierrezia sarothrae 总被引:1,自引:0,他引:1
Hydraulic lift occurs in some deep-rooted shrub and herbaceous species. In this process, water taken up by deep roots from
the moist subsoil is delivered to the drier topsoil where it is later reabsorbed by shallow roots. However, little is known
about the existence of hydraulic lift in shallow-rooted xeric species. The objectives of this study were 1) to ascertain whether
hydraulic lift exists in Gutierrezia sarothrae (broom snakeweed), a widespread North American desert species with a shallow root system, grown in pot and field conditions
and 2) if it does, how much water can be transferred from the subsoil to the 30 cm topsoil during the night. Snakeweed seedlings
were transplanted in buried pots allowing the deeper roots to grow into the subsoil 30 cm below the surface. Soil water content
inside and outside of the pot was measured seasonally and diurnally with time domain reflectometry technique (TDR). An increase
in water content was detected in the pot after the plant was covered for 3 h by an opaque plastic bag during the day, suggesting
hydraulic lift from deeper depths and exudation of water into the drier topsoil. Root exudation was also observed on native
range sites dominated by snakeweed. Water efflux in the pot was 271 g per plant per night. which was equivalent to 15.3% of
the extrapolated, porometer-derived whole-plant daily transpiration. Hydraulic lift observed in Gutierrezia improved water uptake during the day when evaporative demand is high and less water is available in the topsoil. We concluded
that hydraulic lift might help snakeweed to alleviate the effect of water stress. 相似文献
9.
10.