全文获取类型
收费全文 | 699篇 |
免费 | 88篇 |
出版年
2022年 | 5篇 |
2021年 | 12篇 |
2020年 | 4篇 |
2019年 | 6篇 |
2018年 | 14篇 |
2017年 | 13篇 |
2016年 | 18篇 |
2015年 | 27篇 |
2014年 | 16篇 |
2013年 | 31篇 |
2012年 | 30篇 |
2011年 | 25篇 |
2010年 | 16篇 |
2009年 | 26篇 |
2008年 | 18篇 |
2007年 | 22篇 |
2006年 | 23篇 |
2005年 | 19篇 |
2004年 | 16篇 |
2003年 | 20篇 |
2002年 | 23篇 |
2001年 | 20篇 |
2000年 | 23篇 |
1999年 | 31篇 |
1998年 | 14篇 |
1997年 | 9篇 |
1996年 | 10篇 |
1995年 | 9篇 |
1993年 | 7篇 |
1992年 | 15篇 |
1991年 | 13篇 |
1990年 | 22篇 |
1989年 | 14篇 |
1988年 | 18篇 |
1987年 | 8篇 |
1986年 | 7篇 |
1985年 | 8篇 |
1984年 | 11篇 |
1983年 | 8篇 |
1982年 | 10篇 |
1981年 | 13篇 |
1980年 | 5篇 |
1979年 | 16篇 |
1978年 | 20篇 |
1977年 | 11篇 |
1976年 | 11篇 |
1975年 | 7篇 |
1974年 | 7篇 |
1973年 | 7篇 |
1972年 | 4篇 |
排序方式: 共有787条查询结果,搜索用时 15 毫秒
101.
102.
103.
The available world literature (since Friedman''s and Levy''s comprehensive report in 1937) regarding actinomycosis of the central nervous system is reviewed. Only cases proved by culture were included in this analysis. A total of 17 cases was collected and an additional patient with this entity is described.The important differences between actinomycosis and nocardiosis are discussed. A definite diagnosis of actinomycosis was possible only when anaerobic cultures of cerebrospinal fluid or material obtained from a brain abscess yielded colonies of typical Actinomyces organisms. The characteristic result of infection of the brain by this fungus was abscess formation, and this occurred in all except one of the cases reviewed. Penicillin appears to be the drug of choice in treatment and, where possible, surgical excision of the cerebral abscess should be undertaken. 相似文献
104.
Assessing the effects of repeated handling on the physiology and condition of semi‐precocial nestlings
下载免费PDF全文
![点击此处可从《Ibis》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Repeated exposure to elevated levels of glucocorticoids during development can have long‐term detrimental effects on survival and fitness, potentially associated with increased telomere attrition. Nestling birds are regularly handled for ecological research, yet few authors have considered the potential for handling‐induced stress to influence hormonally mediated phenotypic development or bias interpretations of subsequent focal measurements. We experimentally manipulated the handling experience of the semi‐precocial nestlings of European Storm Petrel Hydrobates pelagicus to simulate handling in a typical field study and examined cumulative effects on physiology and condition in late postnatal development. Neither baseline corticosterone (the primary glucocorticoid in birds), telomere length nor body condition varied with the number of handling episodes. The absence of a response could be explained if Storm Petrels did not perceive handling to be stressful or if there is dissociation of the hypothalamic–pituitary–adrenal axis from stressful stimuli in early life. Eliciting a response to a stressor may be maladaptive for cavity‐dwelling young that are unable to escape or defend themselves. Furthermore, avoiding elevated overall glucocorticoid exposure may be particularly important in a long‐lived species, in which accelerated early‐life telomere erosion could impact negatively upon longevity. We propose that the level of colony‐wide disturbance induced by investigator handling of young could be important in underlining species‐specific responses. Storm Petrel nestlings appear unresponsive to investigator handling within the limits of handling in a typical field study and handling at this level should not bias physiological and morphological measurements. 相似文献
105.
106.
107.
108.
Although Porphyra is commercially farmed in many countries, in South Africa only small harvests of wild populations for sale as nori have been
carried out. The discovery that Porphyra improves growth of South African abalone (Haliotis midae) farmed inland-based tanks has led to increased pressure to harvest wild populations. This paper reports on a survey of the
distribution and seasonality of Porphyra in the southern Western Cape. Porphyrawas present at all sites surveyed, and showed considerable temporal variation. A significant amount of the Porphyra present is in reserves and therefore protected from harvesting. Close rexamination of one site revealed seasonal populations
of Porphyra that occupied different niches dependent on season. Recruitment peaked in spring and autumn, leading to dense summer and
winter populations. Summer populations generally grew lower in the eulittoral than winter populations. No pattern in the mortality
of larger thalli wasde tected, though sporeling mortality was high following recruitment peaks. Although it seems that most
sites in the southern Western Cape are suitable for harvesting, the taxonomy of the genus in the region urgently needs revision
if populations are to be appropriately managed.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
109.
110.
Helen R. Please Jonathan H. Vas Nunes Rashida Patel Gerd Pluschke Mohamed Tholley Marie-Thers Ruf William Bolton Julian A. Scott Martin P. Grobusch Hkon A. Bolkan Julia M. Brown David G. Jayne 《PLoS neglected tropical diseases》2021,15(10)
BackgroundChronic wounds pose a significant healthcare burden in low- and middle-income countries. Buruli ulcer (BU), caused by Mycobacterium ulcerans infection, causes wounds with high morbidity and financial burden. Although highly endemic in West and Central Africa, the presence of BU in Sierra Leone is not well described. This study aimed to confirm or exclude BU in suspected cases of chronic wounds presenting to Masanga Hospital, Sierra Leone.MethodologyDemographics, baseline clinical data, and quality of life scores were collected from patients with wounds suspected to be BU. Wound tissue samples were acquired and transported to the Swiss Tropical and Public Health Institute, Switzerland, for analysis to detect Mycobacterium ulcerans using qPCR, microscopic smear examination, and histopathology, as per World Health Organization (WHO) recommendations.FindingsTwenty-one participants with wounds suspected to be BU were enrolled over 4-weeks (Feb-March 2019). Participants were predominantly young working males (62% male, 38% female, mean 35yrs, 90% employed in an occupation or as a student) with large, single, ulcerating wounds (mean diameter 9.4cm, 86% single wound) exclusively of the lower limbs (60% foot, 40% lower leg) present for a mean 15 months. The majority reported frequent exposure to water outdoors (76%). Self-reports of over-the-counter antibiotic use prior to presentation was high (81%), as was history of trauma (38%) and surgical interventions prior to enrolment (48%). Regarding laboratory investigation, all samples were negative for BU by microscopy, histopathology, and qPCR. Histopathology analysis revealed heavy bacterial load in many of the samples. The study had excellent participant recruitment, however follow-up proved difficult.ConclusionsBU was not confirmed as a cause of chronic ulceration in our cohort of suspected cases, as judged by laboratory analysis according to WHO standards. This does not exclude the presence of BU in the region, and the definitive cause of these treatment-resistance chronic wounds is uncertain. 相似文献