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   329篇
  免费   16篇
  国内免费   23篇
儿科学   27篇
妇产科学   4篇
基础医学   19篇
口腔科学   8篇
临床医学   46篇
内科学   78篇
皮肤病学   5篇
神经病学   12篇
特种医学   44篇
外科学   22篇
综合类   40篇
预防医学   10篇
眼科学   5篇
药学   29篇
肿瘤学   19篇
  2024年   1篇
  2022年   5篇
  2021年   3篇
  2020年   6篇
  2019年   4篇
  2018年   9篇
  2017年   8篇
  2016年   10篇
  2015年   7篇
  2014年   13篇
  2013年   13篇
  2012年   6篇
  2011年   6篇
  2010年   15篇
  2009年   14篇
  2008年   9篇
  2007年   20篇
  2006年   9篇
  2005年   3篇
  2004年   5篇
  2003年   5篇
  2002年   5篇
  2001年   9篇
  2000年   4篇
  1999年   4篇
  1998年   21篇
  1997年   19篇
  1996年   19篇
  1995年   9篇
  1994年   19篇
  1993年   11篇
  1992年   5篇
  1991年   6篇
  1989年   8篇
  1988年   14篇
  1987年   5篇
  1986年   7篇
  1985年   5篇
  1984年   5篇
  1983年   2篇
  1982年   5篇
  1981年   5篇
  1980年   5篇
  1978年   1篇
  1977年   2篇
  1976年   1篇
  1975年   1篇
排序方式: 共有368条查询结果,搜索用时 15 毫秒
1.
2.
范尚坦  苏中武  李承祜 《药学学报》1988,23(12):944-952
本文对模式产地的山药Piper haneei Maxim, var, hancei Maxim,和腺鳞蒟P. kancei Maxim var. squamiglanduferum Fan var. nov.进行了原植物形态特征和花序轴、花序梗、茎、叶的显微特征以及化学成分的TLC及UV比较。挥发油的GC—MS研究共鉴定出38个成分,其中28个是胡椒属植物中首次报道的成分。结果证明了在福建长期以来被认为是山药的腺鳞蒟与模式产地的山药有较大差别,尤其是腺鳞蒟叶上表面有腺鳞,是迄今为止第1个发现具有腺鳞的胡椒属植物。据此把腺鳞蒟作为新变种从山药中分出。腺鳞药是福建南部海风藤主要来源之一。  相似文献   
3.
目的:建立家猪胸腰段脊髓火器贯通伤模型和改良Allen's打击伤后全瘫模型,观察伤后促凋亡基因p53基因的早期表达。方法:实验于2005-05/08在解放军第一七五医院实验室完成。取健康雄性家猪20只,单纯随机分为3组:①火器伤组:9只,在全麻状态下制作胸腰段(L1~L2)脊髓火器伤模型,分为伤后1,3,6h3个时间处死。②打击伤组:9只,L1节段脊髓行改良Allen’s打击,致伤力为500g·cm,处死时间同前。③空白对照组:2只,只麻醉,不造模,伤后6h处死。伤后不同时间点(伤后1,3,6h)和不同节段(伤点、近伤点、中伤点及远伤点)取材,采用SP法进行P53蛋白免疫组化染色,用TJTY-300型全自动图像分析仪测量P53免疫组织化学染色阳性物质吸光度。结果:经补充后20只猪进入结果分析。①脊髓损伤后3h打击伤组伤点,火器伤组近伤段脊髓P53蛋白的表达高于空白对照组(P<0.001),随着时间推移,打击伤组和火器伤组P53蛋白的表达呈升高趋势(P<0.001),且火器伤组要高于打击伤组(P<0.0001)。②在脊髓损伤后6h,打击伤组仅在伤点和近伤段P53蛋白的表达高于空白对照组(5.57±0.82,3.21±0.43,P<0.05),而火器伤组近伤段、中伤段及远段伤均高于空白对照组(6.46±0.66,4.27±0.39,1.16±0.17,P<0.05)。结论:①细胞凋亡基因p53在脊髓损伤中的表达有一定的时空性,在脊髓损伤后3h出现P53蛋白表达量的增加。②脊髓火器伤的波及范围较打击伤更为广泛。  相似文献   
4.
目的:探讨颈椎椎后肌肉组织Na -K -ATP酶活性变化与颈椎病的关系。资料来源:应用计算机检索PubMed1988-01/2004-12相关骨骼肌损伤与肌组织Na -K -ATP酶关系的文献,检索词“Na -K pump,Na -K -ATPase,muscle”,限定文献语言种类为English。同时计算机检索CNKI1990-01/2005-12相关Na -K -ATP酶与骨骼肌损伤的关系及颈椎病发病病因的文献,检索词“Na -K -ATP酶,骨骼肌,颈椎病病因”,限定文献语言种类为中文。资料选择:对资料进行初审,选取包括Na -K -ATP酶与肌组织损伤关系的文献,开始查找全文。纳入标准:Na -K -ATP酶活性变化与骨骼肌损伤密切相关的文献研究。排除标准:重复研究,Meta分析类文章。资料提炼:共检索到939篇关于Na -K -ATP酶与骨骼肌损伤相关方面的文献,最终纳入20篇符合标准的文献。资料综合:众多研究表明,Na 、K 与骨骼肌的兴奋、收缩、疲劳有密切关系,而Na -K -ATP酶又是调节细胞内外Na 、K 浓度必不可少的高分子蛋白,也就是说,骨骼肌一系列活动均离不开Na -K -ATP酶,Na -K -ATP酶活性变化与骨骼肌损伤是相互影响的。而强迫屈颈体位作为颈椎病发病的危险因素之一,可使颈椎椎后肌肉Na -K -ATP酶活性降低,酶活性降低致使肌细胞损伤,并最终导致骨骼肌损伤而发病。结论:以颈椎椎后肌肉酶活性的变化来阐释中医药对颈椎病确切疗效的相关研究未见,这有待于进一步研究,以充分展示中医药在颈椎病等相关疾病中的治疗优势。  相似文献   
5.
The goal of this study was to identify an injectable anesthetic protocol that provides sedation sufficient for peripheral vascular catheterization, intubation, and transport while minimizing cardiovascular changes in Yorkshire and Yucatan pigs with and without cardiovascular injury and intervention (CI). Phase 1 examined the safety and efficacy of acepromazine–ketamine, diazepam–ketamine, midazolam–ketamine, and medetomidine–ketamine in 5 healthy Yorkshire pigs. For each drug combination, we obtained multiple measurements of heart rate, blood pressure, respiratory rate, temperature, sedation score, ability to catheterize and intubate, and recovery score. Phase 2 evaluated and refined the dose of the most effective Phase 1 anesthetic combination (midazolam–ketamine) in healthy and CI Yorkshire pigs (n = 53 trials). Phase 3 mirrored Phase 2 but tested midazolam–ketamine in healthy and CI Yucatan pigs (n = 34 trials). Midazolam (0.5 mg/kg)–ketamine (25 to 27 mg/kg) was the most effective anesthetic combination in healthy Yorkshire pigs, but this dose was less effective in healthy Yucatan pigs and CI Yorkshire and Yucatan pigs. Midazolam–ketamine resulted in tachycardia and apnea more frequently in CI pigs than healthy pigs. This combination also caused vomiting in one CI Yucatan pig. Overall, midazolam–ketamine provided safe and effective sedation for catheterization and intubation of both healthy and CI pigs. This study suggests Yucatan pigs may require a higher dose midazolam–ketamine to achieve the same level of sedation as that in Yorkshire pigs. Although anesthetic complication rates were higher in CI pigs, our results indicate that midazolam–ketamine can be safely used for sedation of both pig breeds with and without CI.Abbreviation: CI, cardiovascular injury and interventionPigs (Sus scrofa) are common models of cardiovascular injury and intervention (CI) that largely have replaced traditional canine cardiology models. Advantages of swine compared with dogs include anatomic and physiologic characteristics similar to humans, such as similar coronary artery distribution and effective collateralized blood flow to the myocardium after coronary artery blockage.23 However, pigs are difficult to restrain and anesthetize due to their size and resistance to sedative drug combinations, including those with morphine.24 Injectable sedative drugs may result in cardiovascular and respiratory effects such as increased cardiac work and oxygen consumption, tachycardia, bradycardia, apnea, hypertension, and hypotension.5,6,8-12,14,19,20,25-29 These side effects can pose considerable problems for CI pigs, and anesthesia protocols with minimal effects on cardiovascular function are needed. A literature review revealed no published studies of anesthetic protocols in swine with existing cardiovascular injury; published research is limited to investigating anesthesia protocols for experimental induction of CI or determining in vitro and in vivo drug effects on healthy cardiovascular systems.4-6,8-12,14,19-21,25-29 Other published studies have limited investigations to studying sedative and physiologic effects in healthy Yorkshire, Yucatan, mixed-breed, Landrace, and Gottingen miniature swine.2,3,10,13,17,18,20-22We conducted the current study to address the need for a systematic investigation of anesthetic protocols in CI Yorkshire and Yucatan pigs. The goals of this study were to determine an injectable-only anesthetic protocol for both Yorkshire and Yucatan pigs that yielded sufficient sedation for peripheral vascular catheterization, sufficient duration for transport, and minimal cardiovascular effects while being safe and effective for CI pigs.  相似文献   
6.
7.
8.
9.

Background

In the adult abdomen of Drosophila, the shafts of mechanosensory bristles point consistently from anterior to posterior. This is an example of planar cell polarity (PCP); some genes responsible for PCP have been identified. Each adult bristle is made by a clone of four cells, including the neuron that innervates it, but little is known as to how far the formation or positions of these cells depends on PCP. The neurons include a single dendrite and an axon; it is not known whether the orientation of these processes is influenced by PCP.

Results

We describe the development of the abdominal mechanosensory bristles in detail. The division of the precursor cell gives two daughters, one (pIIa) divides to give rise to the bristle shaft and socket cell and the other (pIIb) generates the neuron, the sheath and the fifth cell. Although the bristles and their associated shaft and socket cells are consistently oriented, the positioning and behaviour of the neuron, the sheath and the fifth cell, as well as the orientation of the axons and the dendritic paths, depend on location. For example, in the anterior zone of the segment, the axons grow posteriorly, while in the posterior zone, they grow anteriorly. Manipulating the PCP genes can reverse bristle orientation, change the path taken by the dendrite and the position of the cell body of the neuron. However, the paths taken by the axon are not affected.

Conclusion

PCP genes, such as starry night and dachsous orient the bristles and position the neuronal cell body and affect the shape of the dendrites. However, these PCP genes do not appear to change the paths followed by the sensory axons, which must, therefore, be polarised by other factors.
  相似文献   
10.
    
BACKGROUND The management of proximal esophageal cancer differs from that of tumors located in the mid and lower part of the esophagus due to the close vicinity of vital structures. Non-surgical treatment options like radiotherapy and definitive chemoradiation(CRT) have been implemented. The trends in(non-)surgical treatment and its impact on overall survival(OS) in patients with proximal esophageal cancer are unclear, related to its rare disease status. To optimize treatment strategies and counseling of patients with proximal esophageal cancer,it is therefore essential to gain more insight through real-life studies.AIM To establish trends in treatment and OS in patients with proximal esophageal cancer.METHODS In this population-based study, patients with proximal esophageal cancer diagnosed between 1989 and 2014 were identified in the Netherlands Cancer Registry. The proximal esophagus consists of the cervical esophagus and the upper thoracic section, extending to 24 cm from the incisors. Trends in radiotherapy, chemotherapy, and surgery, and OS were assessed. Analyses were stratified by presence of distant metastasis. Multivariable Cox proportional hazards regression analyses was performed to assess the effect of period of diagnosis on OS, adjusted for patient, tumor, and treatment characteristics.RESULTS In total, 2783 patients were included. Over the study period, the use of radiotherapy, resection, and CRT in non-metastatic disease changed from 53%,23%, and 1% in 1989-1994 to 21%, 9%, and 49% in 2010-2014, respectively. In metastatic disease, the use of chemotherapy and radiotherapy increased over time. Median OS of the total population increased from 7.3 mo [95% confidence interval(CI): 6.4-8.1] in 1989-1994 to 9.5 mo(95%CI: 8.1-10.8) in 2010-2014(logrank P 0.001). In non-metastatic disease, 5-year OS rates improved from 5%(95%CI: 3%-7%) in 1989-1994 to 13%(95%CI: 9%-17%) in 2010-2014(logrank P 0.001). Multivariable regression analysis demonstrated a significant treatment effect over time on survival. In metastatic disease, median OS was 3.8 mo(95%CI:2.5-5.1) in 1989-1994, and 5.1 mo(95%CI: 4.3-5.9) in 2010-2014(logrank P = 0.26).CONCLUSION OS significantly improved in non-metastatic proximal esophageal cancer, likely to be associated with an increased use of CRT. Patterns in metastatic disease did not change significantly over time.  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