全文获取类型
收费全文 | 1913篇 |
免费 | 191篇 |
国内免费 | 9篇 |
专业分类
耳鼻咽喉 | 5篇 |
儿科学 | 70篇 |
妇产科学 | 13篇 |
基础医学 | 283篇 |
口腔科学 | 56篇 |
临床医学 | 200篇 |
内科学 | 461篇 |
皮肤病学 | 49篇 |
神经病学 | 91篇 |
特种医学 | 159篇 |
外国民族医学 | 1篇 |
外科学 | 187篇 |
综合类 | 61篇 |
预防医学 | 144篇 |
眼科学 | 149篇 |
药学 | 108篇 |
中国医学 | 1篇 |
肿瘤学 | 75篇 |
出版年
2021年 | 32篇 |
2020年 | 21篇 |
2019年 | 22篇 |
2018年 | 24篇 |
2017年 | 24篇 |
2016年 | 24篇 |
2015年 | 48篇 |
2014年 | 38篇 |
2013年 | 67篇 |
2012年 | 64篇 |
2011年 | 79篇 |
2010年 | 57篇 |
2009年 | 67篇 |
2008年 | 61篇 |
2007年 | 79篇 |
2006年 | 59篇 |
2005年 | 54篇 |
2004年 | 75篇 |
2003年 | 42篇 |
2002年 | 30篇 |
2001年 | 53篇 |
2000年 | 31篇 |
1999年 | 46篇 |
1998年 | 62篇 |
1997年 | 70篇 |
1996年 | 68篇 |
1995年 | 45篇 |
1994年 | 44篇 |
1993年 | 47篇 |
1992年 | 29篇 |
1991年 | 29篇 |
1990年 | 35篇 |
1989年 | 31篇 |
1988年 | 42篇 |
1987年 | 51篇 |
1986年 | 44篇 |
1985年 | 37篇 |
1984年 | 33篇 |
1983年 | 29篇 |
1982年 | 25篇 |
1981年 | 16篇 |
1980年 | 15篇 |
1979年 | 14篇 |
1978年 | 25篇 |
1977年 | 17篇 |
1976年 | 20篇 |
1975年 | 19篇 |
1974年 | 14篇 |
1973年 | 15篇 |
1970年 | 16篇 |
排序方式: 共有2113条查询结果,搜索用时 15 毫秒
41.
Serogroup B Meningococcal Disease Outbreak and Carriage Evaluation at a College — Rhode Island, 2015
Heidi M. Soeters Lucy A. McNamara Melissa Whaley Xin Wang Nicole Alexander-Scott Koren V. Kanadanian Catherine M. Kelleher Jessica MacNeil Stacey W. Martin Nathan Raines Steven Sears Cynthia Vanner Jeni Vuong Utpala Bandy Kenneth Sicard Manisha Patel 《MMWR. Morbidity and mortality weekly report》2015,64(22):606-607
42.
Muscle activity during chest wall restriction and positive pressure breathing in man. 总被引:3,自引:0,他引:3
The effects of sustained constriction of the rib cage (RCC), constriction of the abdomen (AC) and of breathing against a positive pressure of 10 cms of water (PPB) were studied in four normal subjects with moderate constant hypercapnia. Intercostal electrical activity (Eic) was measured by implanted wire electrodes and diaphragmatic electrical activity (Edia) by oesophageal electrodes. There was no fixed relation between Edia and VT. VT was unaltered during AC and RCC: Edia was unaltered during AC but increased during RCC. The response to PPB without constriction varied: three subjects increased end-expiratory VL with increase in Edia and inspiratory Eic. One subject initially, and one subject after training, maintained end-expiratory VL constant with no change in Edia and an increase in expiratory Eic. When PPB was applied during AC and RCC there was an increase in Edia proportional to end-expiratory lung volume. The overall response to distortion was determined by voluntary choice, but muscle electrical activity reflected chest wall configuration: when the diaphragm was shorter and at a mechanical disadvantage its electrical activity increased. This was compatible with a reflex with afferent information from diaphragm tendon organ and muscle spindle receptors. 相似文献
43.
Summary Sarcoidosis involves the liver in approximately 65% of all patients, but laboratory evidence of liver disease is usually minimal and clinical manifestations rare. In two patients with massive liver infiltration, both followed closely with serial liver function tests and percutaneous biopsies, one died after repeated hemorrhage from esophageal varices 3 years after diagnosis, while the other, still living, has developed no evidence of portal hypertension after 4 years, although her liver changes were fully as severe. Both were treated with steroids. The mechanisms of the portal hypertension is still in doubt, although there is some evidence that it is due to presinusoidal block, without the classic pathologic changes of cirrhosis. 相似文献
44.
Formoterol as relief medication in asthma: a worldwide safety and effectiveness trial. 总被引:5,自引:0,他引:5
R A Pauwels M R Sears M Campbell C Villasante S Huang A Lindh W Petermann M Aubier G Schwabe T Bengtsson 《The European respiratory journal》2003,22(5):787-794
The aim of the study was to compare the safety and effectiveness of as-needed formoterol with salbutamol in a large international real-life asthma study. Children and adults (n=18,124) were randomised to 6 months as-needed treatment with open-label formoterol 4.5 microg Turbuhaler or salbutamol 200 microg pressurised metered dose inhaler or equivalent. Primary safety variables were asthma-related and nonasthma-related serious adverse events (SAE)s and adverse events (AE)s resulting in discontinuation (DAE)s. The primary efficacy variable was time to first asthma exacerbation. The incidences of AEs, SAEs and DAEs arising from SAEs were not significantly different between treatments. DAEs for nonserious AEs were higher with formoterol. Asthma-related AEs decreased with formoterol (1,098 (12.3%) versus 1,206 (13.5%)), asthma-related SAEs were similar (108 (1.2%) versus 121 (1.4%)) but more asthma-related DAEs occurred in the formoterol group (89 (1.0%) versus 48 (0.5%)). Time to first exacerbation was prolonged (hazard ratio 0.86) and less as-needed and maintenance medication was used with formoterol. Reductions of exacerbations with as-needed formoterol versus salbutamol increased with increasing age and asthma medication level. This real-life study demonstrates that formoterol as-needed has a similar safety profile to salbutamol, and its use as a reliever therapy is associated with fewer asthma symptoms and exacerbations. 相似文献
45.
Scott W. Shurmur Ubeydullah Deligonul Ralph W. Rayner Thomas W. Sears Thomas R. Porter 《Catheterization and cardiovascular interventions》1994,32(2):174-177
A 60-year-old man underwent directional coronary atherectomy (DCA) of the mid portion of a large, anatomically dominant left circumflex coronary artery, resulting in propagating transverse dissection and subsequent complete distal occlusion. Intravascular ultrasound imaging (IVUS) of the dissected segment demonstrated the entry point of the dissection, and systolic compression of the true vessel lumen, prior to angiographic deterioration of distal coronary flow. © 1994 Wiley-Liss,Inc.. 相似文献
46.
Angela Huttner Alice Bricheux Carianne J.M. Buurmeijer-van Dijk Matthew Harvey Alison Holmes Britta Lassmann Valéry Lavergne Alexandra Mailles Marc Mendelson Nicolas Muller Maurizio Sanguinetti Cynthia Sears Chrysanthi Skevaki Uzma Syed Salandra Thomas Talia H. Swartz Talia H. Swartz 《Clinical microbiology and infection》2021,27(5):704-707
BackgroundThough women increasingly make up the majority of medical-school and other science graduates, they remain a minority in academic biomedical settings, where they are less likely to hold leadership positions or be awarded research funding. A major factor is the career breaks that women disproportionately take to see to familial duties. They experience a related, but overlooked, hurdle upon their return: they are often too old to be eligible for ‘early-career researcher’ grants and ‘career-development’ awards, which are stepping stones to leadership positions in many institutions and which determine the demographics of their hierarchies for decades to come. Though age limits are imposed to protect young applicants from more experienced seniors, they have an unintended side effect of excluding returning workers, still disproportionately women, from the running.MethodsIn this joint effort by the European Society of Clinical Microbiology and Infectious Diseases, the Federation of European Microbiological Societies, the Infectious Disease Society of America, the International Society for Infectious Diseases and the Swiss Society for Infectious Diseases, we invited all European Congress of Clinical Microbiology and Infectious Diseases-affiliated medical societies and funding bodies to participate in a survey on current ‘early-career’ application restrictions and measures taken to provide protections for career breaks.RecommendationsThe following simple consensus recommendations are geared to funding bodies, academic societies and other organizations for the fair handling of eligibility for early-career awards: 1. Apply a professional, not physiological, age limit to applicants. 2. State clearly in the award announcement that career breaks will be factored into applicants' evaluations such that: ? Time absent is time extended: for every full-time equivalent of career break taken, the same full-time equivalent will be extended to the professional age limit. ? Opportunity costs will also be taken into account: people who take career breaks risk additional opportunity costs, with work that they did before the career break often being forgotten or poorly documented, particularly in bibliometric accounting. Although there is no standardized metric to measure additional opportunity costs, organizations should (a) keep in mind their existence when judging applicants' submissions, and (b) note clearly in the award announcement that opportunity costs of career breaks are also taken into account. 3. State clearly that further considerations can be undertaken, using more individualized criteria that are specific to the applicant population and the award in question.The working group welcomes feedback so that these recommendations can be improved and updated as needed. 相似文献
47.
The relative importance of thrombin inhibition and factor Xa inhibition to the antithrombotic effects of heparin 总被引:4,自引:1,他引:4
The relative importance of antithrombin and anti-factor Xa activities of heparin fractions required to achieve optimal antithrombotic effects is unknown. To study this, we measured the effects of standard heparin, an octasaccharide heparin fraction (anti-factor Xa activity only), and dermatan sulfate (antithrombin activity only) on the prevention of thrombosis and related this to their anticoagulant effects in vivo in rabbits. Thrombosis was measured as the incorporation of 125I- fibrinogen into tissue thromboplastin-induced thrombi using a Wessler- type model. Ex vivo changes in thrombin clotting time (TCT) were used as an index of antithrombin activity, and a chromogenic anti-factor Xa assay was used to measure anti-factor Xa activity. In addition, the ability of the three sulfated polysaccharides to simultaneously inhibit the generation of thrombin activity and to enhance the inactivation of the factor Xa added to initiate thrombin generation in plasma was determined. Standard heparin, in a dose of 10 anti-factor Xa U/kg, inhibited thrombus formation by 90%, prolonged the TCT by two seconds, and resulted in an anti-factor Xa level of 0.32 U/mL. The octasaccharide heparin fraction, in a dose of 10 anti-factor Xa U/kg, inhibited thrombus formation by 41%, had no effect on the TCT, and resulted in an anti-factor Xa level of 0.28 U/mL. Higher doses of the octasaccharide resulted in a further increase in the anti-factor Xa levels but had no further effect on thrombus formation. Dermatan sulfate, in a dose of 500 micrograms/kg, inhibited thrombus formation by 95%, but had no affect on the TCT. These results indicate that the antithrombotic effect achieved by inhibiting factor Xa is limited and that better antithrombotic effects are achieved by heparin or heparin- like substances capable of influencing the inactivation and/or the generation of thrombin. 相似文献
48.
49.
50.