全文获取类型
收费全文 | 115207篇 |
免费 | 12447篇 |
国内免费 | 3723篇 |
专业分类
耳鼻咽喉 | 684篇 |
儿科学 | 2696篇 |
妇产科学 | 803篇 |
基础医学 | 8334篇 |
口腔科学 | 573篇 |
临床医学 | 15140篇 |
内科学 | 18966篇 |
皮肤病学 | 607篇 |
神经病学 | 4604篇 |
特种医学 | 4682篇 |
外国民族医学 | 98篇 |
外科学 | 10505篇 |
综合类 | 22412篇 |
现状与发展 | 12篇 |
预防医学 | 6859篇 |
眼科学 | 995篇 |
药学 | 10884篇 |
135篇 | |
中国医学 | 6721篇 |
肿瘤学 | 15667篇 |
出版年
2024年 | 516篇 |
2023年 | 2112篇 |
2022年 | 4319篇 |
2021年 | 5980篇 |
2020年 | 5609篇 |
2019年 | 4421篇 |
2018年 | 4082篇 |
2017年 | 4916篇 |
2016年 | 5105篇 |
2015年 | 4863篇 |
2014年 | 7973篇 |
2013年 | 7881篇 |
2012年 | 6857篇 |
2011年 | 7246篇 |
2010年 | 5873篇 |
2009年 | 5407篇 |
2008年 | 5432篇 |
2007年 | 5874篇 |
2006年 | 5173篇 |
2005年 | 4494篇 |
2004年 | 3620篇 |
2003年 | 3081篇 |
2002年 | 2583篇 |
2001年 | 2389篇 |
2000年 | 1930篇 |
1999年 | 1587篇 |
1998年 | 1336篇 |
1997年 | 1290篇 |
1996年 | 1113篇 |
1995年 | 1025篇 |
1994年 | 946篇 |
1993年 | 727篇 |
1992年 | 804篇 |
1991年 | 645篇 |
1990年 | 549篇 |
1989年 | 471篇 |
1988年 | 458篇 |
1987年 | 415篇 |
1986年 | 337篇 |
1985年 | 327篇 |
1984年 | 307篇 |
1983年 | 206篇 |
1982年 | 230篇 |
1981年 | 164篇 |
1980年 | 146篇 |
1979年 | 140篇 |
1978年 | 126篇 |
1977年 | 73篇 |
1976年 | 70篇 |
1975年 | 55篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
71.
72.
Granular cell tumours rarely involve the lower respiratory tract. We report eight cases surgically resected at our institution. There were four females and four males, aged between 18 to 56 years (mean 40). One tumour associated with a peripheral lung adenocarcinoma was asymptomatic. The other lesions presented with obstructive pneumonitis (3 cases), haemoptysis (2), dyspnea (1) or cough (1). These tumours were tracheal (1) or bronchial (6) and one case was located in the lung parenchyma. Four cases were multicentric with associated lesions located in a bronchus (2), the oesophagus (1) or a mediastinal lymph node (1). All tumours, with the largest diameter ranging from 0.5–4.5 cm, were histologically invasive. The tumours were positive for S-100 protein, neuron specific enolase, KP1 (CD68) and vimentin. No tumour expressed desmin, keratin or p53 oncoprotein. Our study demonstrates that, in spite of marked anatomical and clinical polymorphism, the rare granular cell tumours of the lower respiratory tract have a constant histological appearance. Our observations confirm that large tumours (> 8–10 mm) usually extend beyond the tracheo-bronchial cartilages and, therefore, only surgical treatment may avoid recurrence. 相似文献
73.
通过42例重型肺心病、7例轻型肺心病、16例肺心病伴发冠心病患者和30例正常人在静息状态下的左右心脏射血分数及其临床资料的分析表明,重型肺心病患者在病情的急性发作期,存在有不同程度的左心功能不全,而轻型肺心病患者则无左心功能不全的表现。表明慢性肺心病仅在病程晚期,才由以右心为主的疾病发展成为全心病。本文还对重型肺心病与肺心病伴发冠心病患者的左心功能进行比较,结果表明,肺心病伴发冠心病患者左室功能受损程度更为明显,双重病因导致的左室功能减退,常造成心肌更严重的损害而且不容易恢复。 相似文献
74.
Obstructive and restrictive ventilatory impairment in polyvinylchloride fabrication workers 总被引:1,自引:0,他引:1
P Ernst L De Guire B Armstrong G Thériault 《American journal of industrial medicine》1988,14(3):273-279
Responses to a standardized respiratory symptom questionnaire, spirometry, and cross-shift decreases in lung function between 70 current employees of a polyvinylchloride (PVC) fabrication plant and a control group consisting of 48 men employed in a vegetable packing plant were compared. FEV1/FVC was significantly lower in the PVC workers. Cross-shift drops in Vmax75 of 15% or more were also more prevalent in the exposed group (p = .01). When examining the association between months of work within the exposed workforce and spirometric indices of airway obstruction, no relationship could be demonstrated. However, an inverse dose-response relationship was seen between level of FVC and duration of employment, suggesting a restrictive impairment. While the specific exposures have not been identified, it appears that employment in PVC fabrication may be associated with both obstructive and restrictive ventilatory effects. 相似文献
75.
红细胞不同温度长期冻存后形态和免疫功能的变化及其临床意义 总被引:1,自引:0,他引:1
目的 探讨一种简便、有效的红细胞长期保存的方法。方法 红细胞在-40℃、80℃及-196℃(液氮)不同温度下长期保存18个月后,分别测定冻存前后红细胞平均体积(MCV)、红细胞渗透脆性(RFT)及红细胞免疫功能(RBC-C3bRR、ERPN)。结果 红细胞-40℃长期冻存后,MCV和RFT较冻存前显著提高(P<0.05),RBC-C3bRRt ERPN较冻存前显著降低(P<0.05)。红细胞-80℃、-196℃长期冻存后,MCV、RFT、RBC-C3bRR及ERPN较冻存前无明显改变(P>0.05)。结论 红细胞经-80℃、-196℃长期冻存后,其形态、结构和免疫功能保存良好。-80℃低温冻存是一种简便、有效的红细胞长期保存的方法。 相似文献
76.
Jan E. Zejda Thomas S. Hurst Ernest M. Barber Charles Rhodes James A. Dosman 《American journal of industrial medicine》1993,23(5):743-750
A cross-sectional survey on respiratory health in swine producers showed that 30% of 301 examined men usually used a dust mask when working inside a barn. They did not differ significantly from dust mask nonusers in respect to respiratory symptoms and lung function. This analysis was undertaken to determine whether the respiratory health of dust mask users was associated with reasons why they had started individual respiratory protection. The subjects were recontacted in order to identify those who started using a mask to deliberately prevent symptoms (42 men) and those who started protection because of pre-existing respiratory symptoms (44 men). Not unexpectedly, betweengroup comparisons of respiratory symptoms and lung function suggest that swine producers who wear dust masks for preventive purposes have better respiratory health than those who wear dust masks because of symptoms or those who do not use individual respiratory protection. The individual reasons for starting dust mask usage should be examined among potential determinants of the outcomes of prospective studies which can then provide more valid assessment of the effect of individual respiratory protection. © 1993 Wiley-Liss, Inc. 相似文献
77.
78.
Dennis J. Murphy 《Drug development research》1994,32(4):237-246
The known effects of drugs from a variety of pharmacologic/therapeutic classes on the respiratory system and worldwide regulatory requirements support the need for conducting respiratory evaluations in safety pharmacology. The objective of these studies is to evaluate the potential for drugs to cause secondary pharmacologic or toxicologic effects that influence respiratory function. Changes in respiratory function can result either from alterations in the pumping apparatus that controls the pattern of pulmonary ventilation or from changes in the mechanical properties of the lung that determine the transpulmonary pressures (work) required for lung inflation and deflation. Defects in the pumping apparatus are classified as hypo- or hyperventilation syndromes and are evaluated by examining ventilatory parameters in a conscious animal model. The ventilatory parameters include respiratory rate, tidal volume, minute volume, peak (or mean) inspiratory flow, peak (or mean) expiratory flow, and fractional inspiratory time. Defects in mechanical properties of the lung are classified as obstructive or restrictive disorders and can be evaluated in animal models by performing flow-volume and pressure-volume maneuvers, respectively. The parameters used to detect airway obstruction include peak expiratory flow, forced expiratory flow at 25 and 75% of forced vital capacity, and a timed forced expiratory volume, while the parameters used to detect lung restriction include total lung capacity, inspiratory capacity, functional residual capacity, and compliance. Measurement of dynamic lung resistance and compliance, obtained continuously during tidal breathing, is an alternative method for evaluating obstructive and restrictive disorders, respectively, and is used when the response to drug treatment is expected to be immediate (within minutes post-dose). The species used in the safety pharmacology studies conducted in our laboratory are the same as those used in toxicology studies since pharmacokinetic and toxicologic/pathologic data are available in these species. These data can be used to help select test measurement intervals and doses and to aid in the interpretation of functional change. The techniques and procedures for measuring respiratory function parameters are well established in guinea pigs, rats, and dogs. 相似文献
79.
80.
职业接触氯乙烯对生殖功能影响的调查 总被引:4,自引:0,他引:4
Huang Mei-yuan Institute of Occupational Medicine Chinese Academy of Preventive Medicine Beijing 《中华劳动卫生职业病杂志》1994,12(1):12-15
对全国12个城市中13个聚氯乙烯制造工厂中2736名接触氯乙烯的工人及3442名对照厂工人,进行了生殖功能的流行病学调查研究,结果表明,接触氯乙烯男、女工人的各项生殖结局指标与对照组比较无显著性差异,但女工氯乙烯接触组妊娠合并症的发生率明显高于对照组,表明氯乙烯对女工的妊娠过程有一定影响,因此积极改善劳动条件,不仅对保护工人健康,而且对保护其子代的正常发育成长也有重要意义。 相似文献