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   1697篇
  免费   240篇
  国内免费   16篇
  1953篇
  2024年   11篇
  2023年   29篇
  2022年   60篇
  2021年   102篇
  2020年   96篇
  2019年   73篇
  2018年   58篇
  2017年   63篇
  2016年   53篇
  2015年   92篇
  2014年   174篇
  2013年   148篇
  2012年   107篇
  2011年   118篇
  2010年   75篇
  2009年   59篇
  2008年   64篇
  2007年   75篇
  2006年   71篇
  2005年   39篇
  2004年   46篇
  2003年   41篇
  2002年   33篇
  2001年   10篇
  2000年   19篇
  1999年   15篇
  1998年   17篇
  1997年   24篇
  1996年   13篇
  1995年   13篇
  1994年   14篇
  1993年   17篇
  1992年   13篇
  1991年   9篇
  1990年   7篇
  1989年   8篇
  1988年   6篇
  1987年   5篇
  1986年   5篇
  1985年   6篇
  1984年   8篇
  1983年   4篇
  1982年   9篇
  1981年   5篇
  1980年   6篇
  1979年   6篇
  1978年   6篇
  1977年   4篇
  1971年   3篇
  1970年   3篇
排序方式: 共有1953条查询结果,搜索用时 0 毫秒
1.
The distribution of the pulmonary artery and vein of the orangutan lung was examined. The right pulmonary artery runs obliquely across the ventral side of the right bronchus at the caudally to the right upper lobe bronchiole. It then runs across the dorsal side of the right middle lobe bronchiole. Thereafter it runs obliquely across the dorsal side of the right bronchus, and then along the dorso-medial side of the right bronchus. This course is different from that in other mammals. During its course, it gives off branches which run mainly along the dorsal or lateral side of each bronchiole. The left pulmonary artery runs across the dorsal side of the left middle lobe bronchiole, then along the dorso-lateral side of the left bronchus, giving off branches which run along each bronchiole. The pulmonary veins run mainly the ventral or medial side of, along or between the bronchioles. In the left lung, the left middle lobe vein has two trunks; one enters the left atrium, and the other enters the left lower lobe pulmonary venous trunk. This is also different from that found in most mammals. Finally, the pulmonary veins enter the left atrium with four large veins.  相似文献   
2.
The morphology and life cycle of Pneumocystis carinii were studied in cortico-steroid-treated rats by ultrathin section and freeze-fracture electron microscopy. The following stages of P. carinii were noted: trophic, precyst, and cyst. The crescent-shaped cysts appeared to be intermediate forms between precyst and cyst. The cell wall of the trophic stage showed membrane structures suggestive of protozoan endocytosis, whereas the surface of the precyst stage was smooth. The cell wall of the cyst lacked the specialized structural differentiation of yeasts and resembled that of Plasmodium spp. We conclude that P. carinii belongs to the Protozoa, and is presumably Rhizopoda.  相似文献   
3.
4.
摘要 目的:探讨慢性阻塞性肺疾病(chronic obstructive pulmonary disease,COPD)不同表型评估测试问卷(COPD assessment test,CAT)评分与肺功能及预后的关系。方法:收集361例COPD患者临床资料、CAT评分、肺功能检查结果及肺外合并症、肺内并发症等情况,按临床表型分为肺气肿组(n=200)和支气管炎组(n=161),分析肺气肿组200例和支气管炎组161例COPD患者CAT评分与肺功能及预后的关系。结果:肺气肿组CAT评分高于支气管炎组(P<0.05),一秒用力呼气容积(FEV1)占预计值百分比(FEV1%)、FEV1/用力肺活量(FVC)低于支气管炎组(P<0.05),吸气分数(IC/TLC)低于支气管炎组,残总比(RV/TLC)高于支气管炎组(P<0.05);肺气肿组肺间质性病变、肺动脉高压发生率均高于支气管炎组(P<0.05);支气管炎、肺气肿组CAT评分均与FEV1%、FEV1/FVC、IC/TLC呈负相关(P<0.05),与RV/TLC呈正相关(P<0.05),肺气肿各参数相关度更高(P<0.05);肺气肿组不同CAT评分患者肺间质性病变、肺动脉高压发生率比较差异有统计学意义(P<0.05),支气管炎组不同CAT评分肺动脉高压发生率比较差异有统计学意义(P<0.05),随CAT评分的升高,肺气肿组肺间质性病变、肺动脉高压发生率上升,支气管炎组肺动脉高压发生率上升。结论: COPD肺气肿表型CAT评分较支气管炎表型高,肺功能降低更明显,呈现肺过度通气,气流受限特点,更易并发肺间质纤维化、肺动脉高压,且与CAT评分变化密切相关。  相似文献   
5.
The mechanical properties of the respiratory system are important determinants of its function and can be severely compromised in disease. The assessment of respiratory system mechanical properties is thus essential in the management of some disorders as well as in the evaluation of respiratory system adaptations in response to an acute or chronic process. Most often, lungs and chest wall are treated as a linear dynamic system that can be expressed with differential equations, allowing determination of the system’s parameters, which will reflect the mechanical properties. However, different models that encompass nonlinear characteristics and also multicompartments have been used in several approaches and most specifically in mechanically ventilated patients with acute lung injury. Additionally, the input impedance over a range of frequencies can be assessed with a convenient excitation method allowing the identification of the mechanical characteristics of the central and peripheral airways as well as lung periphery impedance. With the evolution of computational power, the airway pressure and flow can be recorded and stored for hours, and hence continuous monitoring of the respiratory system mechanical properties is already available in some mechanical ventilators. This review aims to describe some of the most frequently used models for the assessment of the respiratory system mechanical properties in both time and frequency domain.  相似文献   
6.
Stereotactic body radiotherapy (SBRT) is rapidly becoming an alternative to surgery for the treatment of early-stage non-small cell lung cancer patients. Lung SBRT is administered in a hypo-fractionated, conformal manner, delivering high doses to the target. To avoid normal-tissue toxicity, it is crucial to limit the exposure of nearby healthy organs-at-risk (OAR).Current image-guided radiotherapy strategies for lung SBRT are mostly based on X-ray imaging modalities. Although still in its infancy, magnetic resonance imaging (MRI) guidance for lung SBRT is not exposure-limited and MRI promises to improve crucial soft-tissue contrast. Looking beyond anatomical imaging, functional MRI is expected to inform treatment decisions and adaptations in the future.This review summarises and discusses how MRI could be advantageous to the different links of the radiotherapy treatment chain for lung SBRT: diagnosis and staging, tumour and OAR delineation, treatment planning, and inter- or intrafractional motion management. Special emphasis is placed on a new generation of hybrid MRI treatment devices and their potential for real-time adaptive radiotherapy.  相似文献   
7.
8.
Magi B  Bargagli E  Bini L  Rottoli P 《Proteomics》2006,6(23):6354-6369
The proteomic approach is complementary to genomics and enables protein composition to be investigated under various clinical conditions. Its application to the study of bronchoalveolar lavage (BAL) is extremely promising. BAL proteomic studies were initially based on two-dimensional electrophoretic separation of complex protein samples and subsequent identification of proteins by different methods. With the techniques available today it is possible to attain many different research objectives. BAL proteomics can contribute to the identification of proteins in alveolar spaces with possible insights into pathogenesis and clinical application for diagnosis, prognosis and therapy. Many proteins with different functions have already been identified in BAL. Some could be biomarkers that need to be individually confirmed by correlation with clinical parameters and validation by other methods on larger cohorts of patients. The standardization of BAL sample preparation and processing for proteomic studies is an important goal that would promote and facilitate clinical applications. Here, we review the principal literature on BAL proteomic analysis applied to the study of lung diseases.  相似文献   
9.
A mouse model for the "sudden death" and "malarial lung" syndromes is described. Mice of the C3H/z strain succumb suddenly approximately 7 days after an infection with Plasmodium berghei becomes patent, at a time when parasitemia is still moderate (6 to 8%). Death could be shown to be due to anaphylactoid shock, probably induced by soluble immune complexes. Increased vascular permeability caused transudation and leakage of serum proteins into the interstitium and the alveoli. The lungs were found to be edematous, with a fine granular precipitate in the alveoli and adherent to the vascular walls. The precipitates reacted with antiglobulins G and M, and could be shown to also contain malaria antigens and C3/4. A dramatic drop in hematocrit was recorded several hours before death, indicating the sudden release of malaria antigens. The myocardium of animals that had died very suddenly showed a patchy loss of phosphorylase activity. This loss of activity was much more extensive, and sometimes almost total, when there had been an agonal period of several (1 to 3) hours before death. In these cases the irreversibility of the myocardial damage was also indicated by the loss of activity of the dehydrogenases, as well as by typical inflammatory reactions of granulocytic and histiocytic infiltrations. The hearts thus presented a typical picture of the acute and peracute shock syndromes. In acute shock cardiac insufficiency develops so suddenly that death ensues before irreversible damage has occurred, and cardiac insufficiency can only be demonstrated by the most sensitive of enzyme histochemical means. In the present case shock was induced by the anaphylactoid activity of immune complexes with the lung as target organ. The described syndrome appears analogous to human "malarial lung."  相似文献   
10.
目的观察人工饲养条件下实验恒河猴肺脏病理改变,探讨实验猴呼吸系统疾病分布规律和病理改变特点,丰富实验猴自发病变基本研究资料。方法对1998~2008年云南地区饲养的自然死亡的155只恒河猴(年龄2~20岁)的肺脏进行病理检查,按年龄分为幼年组、成年组、老年组,并对观察结果进行统计学分析。结果实验猴肺脏主要病变有大叶性肺炎、支气管肺炎、间质性肺炎、肺气肿、支气管扩张症、胸膜炎、肺肉芽肿性炎等12种,出现率最高的为支气管肺炎(18.71%)和大叶性肺炎(16.74%)。恒河猴肺脏病变在不同年龄阶段均有发生,老年猴组肺脏病变发生率最高,疾病类型和发生率在不同年组中分布不相同,统计学分析显示:支气管炎病变成年组发病率明显高于幼年组;肺气肿病变老年组明显高于成年组和幼年组,(P〈0.05)。结论人工饲养条件下死亡实验猴肺脏病变检出率较高,实验猴肺脏病变在不同年龄阶段存在差异,实验猴肺脏病理改变结果丰富了实验猴的基本研究资料,对实验猴的质量控制和相关动物实验有重要价值。  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