首页 | 官方网站   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   2641篇
  免费   112篇
  国内免费   3篇
医药卫生   2756篇
  2023年   14篇
  2021年   23篇
  2020年   16篇
  2019年   24篇
  2018年   38篇
  2017年   32篇
  2016年   51篇
  2015年   64篇
  2014年   56篇
  2013年   88篇
  2012年   118篇
  2011年   112篇
  2010年   74篇
  2009年   67篇
  2008年   120篇
  2007年   129篇
  2006年   110篇
  2005年   104篇
  2004年   120篇
  2003年   102篇
  2002年   87篇
  2001年   108篇
  2000年   99篇
  1999年   87篇
  1997年   19篇
  1996年   16篇
  1995年   14篇
  1992年   46篇
  1991年   51篇
  1990年   46篇
  1989年   44篇
  1988年   34篇
  1987年   45篇
  1986年   41篇
  1985年   48篇
  1984年   26篇
  1983年   29篇
  1982年   21篇
  1981年   33篇
  1979年   38篇
  1978年   24篇
  1976年   15篇
  1975年   17篇
  1974年   29篇
  1973年   24篇
  1972年   18篇
  1971年   25篇
  1970年   20篇
  1968年   15篇
  1967年   18篇
排序方式: 共有2756条查询结果,搜索用时 15 毫秒
1.
Hepatic encephalopathy is a reversible state of altered cognition that may occur in patients with acute or chronic liver disease or porto-systemic shunt, and in which known neurological or psychiatric signs may develop. Nitrogenated substances from intestinal digestion reach the brain without being cleared by their passage through the liver due to the presence of porto-systemic shunt. We report two cases of patients with porto-systemic shunt diagnosed with recurrent chronic hepatic encephalopathy refractory to conventional medical treatment. They were satisfactorily treated with shunt embolization using interventionist radiology techniques.  相似文献   
2.
We correlated MRI features with histopathological findings in an HIV-positive patient with vacuolar myelopathy. On MRI symmetrical nonenhancing high-signal areas in the posterior columns on T2-weighted images result from extensive vacuolation visible on histological sections. Received: 18 November 1997 Accepted: 23 March 1997  相似文献   
3.
Zusammenfassung Die Diagnostik vieler rheumatischer Systemerkrankungen wird heute durch den Nachweis von Autoantik?rpern unterstützt und erleichtert. Für die Serodiagnostik der Rheumatoiden Arthritis (RA) stehen nur die doch wenig spezifischen Rheumafaktoren zur Verfügung. Mit dem Ziel, neue krankheitsspezifische Autoantik?rper nachzuweisen, erfolgte eine besondere Proteinaufarbeitung aus Synovialisbiopsien und anderen Geweben. Western Blots der gewonnenen Proteine wurden eingesetzt, um Seren von RA-Patienten und solchen mit anderen rheumatischen Erkrankungen zu untersuchen. Die signifikanteste Immunreaktion von RA-Patienten richtete sich gegen ein 68k-Antigen, welches vermutlich ubiquit?r exprimiert wird, da es nicht nur in Synovialis, sondern in allen weiteren untersuchten Humangeweben und HeLa-Zellen nachgewiesen werden konnte. Der isoelektrische Punkt liegt bei 5,1, das Protein ist O-glykosyliert und im endoplasmatischen Retikulum und/oder Cytoplasma lokalisiert. Antik?rper gegen dieses 68k-Antigen waren bei 110 von 167 RA-Patienten nachzuweisen, was einer Sensitivit?t von 66% entspricht. Ihr Vorkommen war unabh?ngig vom Rheumafaktornachweis, da sie auch bei 7 von 12 seronegativen RA-Patienten zu finden waren, dagegen nur bei einem Patienten aus einer Kontrollgruppe von 98 Patienten mit anderen rheumatologischen Krankheitsbildern, bei einem von 22 HIV-Patienten und überhaupt nicht bei 55 Gesunden. Daraus resultiert eine RA-Spezifit?t für diesen Antik?rper von 99%. Wegen der auff?lligen Krankheitsspezifit?t der anti-68k-Antik?rper liegt es nahe, nach korrespondierenden autoreaktiven T-Zellen zu suchen, um die Rolle dieser neuen Autoreaktivit?t in dem Pathomechanismus der RA zu analysieren. Eingegangen: 20. Mai 1996 Akzeptiert: 13. Februar 1997  相似文献   
4.
Summary This study was carried out in order: (1) to examine the effects of isolated and combined prolonged exposures to noise and whole-body vibration on hearing, vision and subjectively experienced strain, and (2) to check the combined effects with repeated exposures. Six male subjects were exposed twice to noise (N) at 92 dBA, whole-body vibration (V) in the Z-axis at 4 Hz and 1.0 ms–2 rms, and noise and vibration (NV) for 90 min with each condition. Temporary threshold shifts of hearing (TTS) and their integrals (ITTS) were measured at 4, 6, 10, and 12 kHz. Visual acuity was examined by means of a very sensitive test. Cross-modality matching (CMM) of the handgrip force was used to judge the subjectively experienced strain. NV induced a clear tendency of higher TTS and ITTS than N, with several significant differences most pronounced at 10 kHz. With repeated exposures, the effect of NV decreased, while the reactions to N and V remained unchanged. The individual reactions to NV differed. The influence of the duration of exposures on vision depended on the condition; N caused time-dependent changes, whereas V did not. CMM-data increased with the duration of the exposure during V and NV. N was generally judged to be more straining than V; NV caused higher strain than V during the first 30 min of exposure only. Correlations between different effects suggest certain links between them. Additionally, less motivation — daily obtained by a questionnaire — often correlated with higher ITTS during N and NV. The results also illustrate the combined effects on the individual susceptibility, repetition of exposure, the kind of response, and, possibly, the actual psychic state.Abbreviations CMM cross-modality matching - MVC maximum voluntary contraction force - N exposure condition: noise level 92dBA, no whole-body vibration - NV exposure condition: combined exposure to noise with a level of 92 dBA and wholebody vibration with 4 Hz, 1 ms–2 rms - V exposure condition: whole-body vibration with 4 Hz, 1 ms–2 rms - TTS temporary threshold shift - ITTS integral of temporary threshold shift - WBV whole-body vibration in the common sense This work was done in the Temporary International Research Team on Combined Effects of Noise and Vibration of the Council of Mutual Economic Assistance of the Socialist Countries. The authors gratefully acknowledge the help and assistance of L.-M. Brumm, Y. Bening, M. Godau, G. Weber, and R. Vizcaino.  相似文献   
5.
This prospective study examined the influence of long-term amiodarone therapy on the parameters of the signal-averaged ECG and their relation to simultaneously derived Holter monitoring data. For this purpose, 23 patients with angiographically confirmed dilated cardiomyopathy or coronary heart disease and high-grade ventricular arrhythmias, in whom an average of four class I antiarrhythmic drugs had proven ineffective, were stabilized on amiodarone. Before the beginning of therapy, as well as after 2 months and, subsequently, every 3 months, a resting ECG, a signal-averaged ECG by Simson's method, and Holter monitoring were performed. Compared to the initial measurement, we found a significant increase in the duration of the total filtered QRS complex from an average of 114 +/- 24 ms to 127 +/- 35 ms, while the change in voltage did not reach the significance level. The incidence of late potentials remained largely constant under amiodarone; 10 patients showed a constant late potential, 12 patients had no late potential, and one patient with coronary heart disease developed a new late potential. In the long-term follow-up, we ascertained a relatively high responder rate under amiodarone between 41% and 81%. No relation could be detected between the results of the signal-averaged ECG and those of 24-h Holter monitoring.  相似文献   
6.
7.
8.
Lupus vasculitis     
Anatomical studies have demonstrated the high incidence of vasculitis in SLE, the appearances of which are variable and non-specific, ranging from necrotizing angiitis which is undistinguishable from periarteritis nodosa, to scarring lesions. Micro-angiitis is easily demonstrated in skin lesions and is also encountered to varying degrees in CNS, renal, cardiac, pulmonary and gastrointestinal localisations. Disease of large vessels is more rare and sometimes causes gangrene of the limbs. In SLE, vasculitis should be distinguished from thrombosis related to lupus anticoagulant and from atherosclerosis favoured by chronic steroid therapy but perhaps initiated by vascular deposits of immune complexes during the acute inflammatory stage. The treatment of lupic angiitis is mainly based on steroid therapy. The results are variable, probably due to the fibrous nature of some of the vascular lesions.  相似文献   
9.
Realizing the full potential of immunotoxins   总被引:2,自引:0,他引:2  
When conjugated with antibodies that bind selectively to tumor cells, natural toxins from plants and bacteria represent a potentially powerful form of cancer therapy. Over the last several years, much thought and research effort has been devoted to optimizing the specificity and activity of these hybrid molecules. Here we review some of the insights that have come from detailed analyses of the so-called "first-generation immunotoxins," and discuss how these insights have prompted ideas for more effective design of "second-generation immunotoxins."  相似文献   
10.
Activation of influenza A viruses by trypsin treatment.   总被引:86,自引:0,他引:86  
A comparative analysis has been carried out on the infectivity of virus of several influenza A strains grown in different host systems. Strains A/swine/Shope/31 (Hsw1N1), A/PR/8/34 (HON1), A/FM/1 (H1N1), A/Singapore/1/57 (H2N2), A/equine/Miami/1/63 (Heq2Neq2), and A/chick/Germany/49 (Hav2Neq1) exhibit host-dependent differences in infectivity. Virions grown in embryonated eggs and cultures of chorioallantoic membrane cells are highly infectious, whereas virions grown in cultures of chick embryo cells have a low infectivity that significantly increases after treatment in vitro with trypsin. In contrast, fowl plague viruses do not show host-dependent variations in infectivity. Virions grown in all host systems tested are highly infectious, and the infectivity of virions grown in chick embryo cells cannot be enhanced by trypsin treatment.The activation of virus particles appears to be based on the cleavage of hemagglutinin glycoprotein HA. This concept is supported by the following observations: (i) In virions of low infectivity only uncleaved glycoprotein HA can be detected. Virions of high infectivity exhibit complete or at least partial cleavage of the hemagglutinin. (ii) The activation of virions by trypsin treatment is always paralleled by cleavage of HA. (iii) Cleavage of HA is the only effect which can be detected after trypsin treatment. The neuraminidase is neither inactivated nor removed from the virion. (iv) Studies on recombinants of virus N and fowl plague virus (Rostock) show that host-dependent variation of infectivity and activation by trypsin, features specific for parent virus N, are found only with recombinant N(H)-FPV/Ro(N) but not with recombinant FPV/Ro(H)-N(N).Efficient plaque formation and serial passages are possible only if highly infectious particles are formed in a given host system. Thus, all strains analyzed undergo, in the absence of trypsin, successive growth cycles in eggs and chorioallantoic membrane cells and form plaques in chorioallantoic membrane cells. In contrast, in chick embryo cells only viruses containing the fowl plague virus hemagglutinin produce plaques and replicate under multiple cycle conditions without the addition of trypsin.The data show that cleavage of HA is not a precondition for virus assembly and hemagglutinating activity, but that it is necessary for infectivity. These findings are compatible with the hypothesis that, in addition to its role in adsorption, the hemagglutinin has another function in the infection process and cleavage is required for this function.  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-23

京公网安备 11010802026262号