全文获取类型
收费全文 | 801篇 |
免费 | 105篇 |
国内免费 | 1篇 |
出版年
2021年 | 6篇 |
2020年 | 9篇 |
2018年 | 12篇 |
2017年 | 8篇 |
2016年 | 15篇 |
2015年 | 20篇 |
2014年 | 16篇 |
2013年 | 34篇 |
2012年 | 28篇 |
2011年 | 24篇 |
2010年 | 23篇 |
2009年 | 19篇 |
2008年 | 23篇 |
2007年 | 25篇 |
2006年 | 20篇 |
2005年 | 37篇 |
2004年 | 45篇 |
2003年 | 13篇 |
2002年 | 35篇 |
2001年 | 25篇 |
2000年 | 25篇 |
1999年 | 34篇 |
1998年 | 9篇 |
1997年 | 13篇 |
1996年 | 12篇 |
1995年 | 14篇 |
1994年 | 15篇 |
1993年 | 12篇 |
1992年 | 19篇 |
1991年 | 14篇 |
1990年 | 20篇 |
1989年 | 33篇 |
1988年 | 15篇 |
1987年 | 10篇 |
1986年 | 13篇 |
1985年 | 15篇 |
1984年 | 17篇 |
1983年 | 10篇 |
1980年 | 12篇 |
1978年 | 9篇 |
1976年 | 13篇 |
1975年 | 8篇 |
1973年 | 6篇 |
1972年 | 9篇 |
1971年 | 8篇 |
1970年 | 7篇 |
1969年 | 9篇 |
1967年 | 5篇 |
1966年 | 5篇 |
1962年 | 5篇 |
排序方式: 共有907条查询结果,搜索用时 15 毫秒
61.
Prostaglandin E1 inhibits the pulmonary vascular pressor response to hypoxia and prostaglandin F2alpha. 总被引:1,自引:0,他引:1
In the anesthetised dog an infusion of exogenous prostaglandin E1 (100muG/min) inhibits the pulmonary vascular pressor response to hypoxia. Both 25 and 100muG/min PGE1 can reduce the transient pulmonary hypertension caused by a bolus of prostaglandin F2alpha. This suggests that hypoxia and PGF2alpha may share a final common pathway in producing pulmonary vasoconstriction. These results may help to explain the mechanism by which endotoxin inhibits the pulmonary vascular response to hypoxia. This effect is probably achieved by stimulating the production of an endogenous dilator prostaglandin. Exogenous PGE1 can mimic this effect. 相似文献
62.
GC Wood 《New Zealand journal of zoology.》2013,40(3):186-195
Abstract The Westland petrel (Procellaria westlandica) is an endemic New Zealand species and one of the very few burrowing seabird species still breeding on mainland New Zealand. It nests only on a series of coastal ridgelines near to Punakaiki on the West Coast of the South Island. Between 2002 and 2005, surveys were undertaken at 28 of the 29 known colonies. The area occupied by the colonies was 73 ha; most colonies had fewer than 50 burrows, but six colonies had 201–500 burrows and four colonies had more than 1000 burrows. We find that the current breeding range of Westland petrel and the location of individual colonies are similar to those reported in both the 1950s and 1970s. Based on total burrow counts at 28 colonies and burrow occupancy rates determined by annual monitoring, the annual breeding population is estimated to be between 2954 and 5137 breeding pairs. 相似文献
63.
Abstract The objective of this investigation was to study the effect of pH on the dissociation constants and binding ratios of covalent complexes of thymidylate synthases from Escherichia coli and Lactobacillus casei. 相似文献
64.
65.
Barbara Cheney Paul M. Thompson Simon N. Ingram Philip S. Hammond Peter T. Stevick John W. Durban Ross M. Culloch Simon H. Elwen Laura Mandleberg Vincent M. Janik Nicola J. Quick Valentina ISLAS‐Villanueva Kevin P. Robinson Marina Costa Sonja M. Eisfeld Alice Walters Charlie Phillips Caroline R. Weir Peter G.H. Evans Pia Anderwald Robert J. Reid James B. Reid Ben Wilson 《Mammal Review》2013,43(1):71-88
- 相似文献
66.
67.
68.
Lu Fang Piyushkumar A. Mundra Fenling Fan Abby Galvin Jacquelyn M. Weir Gerard Wong Jaye Chin-Dusting Flavia Cicuttini Peter Meikle Anthony Michael Dart 《Metabolomics : Official journal of the Metabolomic Society》2016,12(8):136
Introduction
Rheumatoid arthritis (RA) is linked to increased cardiovascular morbidity and mortality, not completely explained by traditional risk factors. Importantly, the increased risk occurs despite lower levels of total and low-density lipoprotein cholesterol. Whilst systemic inflammation may be a factor, it is possible that changes in individual lipid species contribute to the increased cardiovascular risk.Objectives
In the present study, we characterized plasma lipidomic profiles in patients with RA in comparison with healthy controls.Methods
Patients with RA (n = 32) and age- and gender-matched healthy volunteers (n = 84) were recruited. Fasting plasma lipid profiles were measured using electrospray-ionisation tandem mass spectrometry. 24 lipid classes and subclasses were measured.Results
Patients with RA had normal total, low-density lipoprotein and high-density lipoprotein cholesterol, but higher triglycerides than controls. Five lipid classes (dihydroceramides, alkylphosphatidylethanolamine, alkenylphosphatidylethanolamine, lysophosphatidylinositol, phosphatidylserine) differed between patients with RA and controls. Then we measured 36 lipid species within these 5 classes and found that 11 lipid species were different between patients with RA and controls. Three lipid classes (dihydroceramides, lysophosphatidylinositol, phosphatidylserine) and 10 lipid species remained significantly associated with RA after adjusting for age, sex, body mass index, current smoking, systolic blood pressure and anti-hypertensive treatment in a binary logistic regression model.Conclusion
This study has identified lipid alterations in RA. These alterations of lipids warrant further investigation as they may be associated with accelerated atherosclerosis and joint inflammation in patient with RA.69.
A stirred microchamber for oxygen consumption rate measurements with pancreatic islets 总被引:1,自引:0,他引:1
Improvements in pancreatic islet transplantation for treatment of diabetes are hindered by the absence of meaningful islet quality assessment methods. Oxygen consumption rate (OCR) has previously been used to assess the quality of organs and primary tissue for transplantation. In this study, we describe and characterize a stirred microchamber for measuring OCR with small quantities of islets. The device has a titanium body with a chamber volume of about 200 microL and is magnetically stirred and water jacketed for temperature control. Oxygen partial pressure (pO(2)) is measured by fluorescence quenching with a fiber optic probe, and OCR is determined from the linear decrease of pO(2) with time. We demonstrate that measurements can be made rapidly and with high precision. Measurements with betaTC3 cells and islets show that OCR is directly proportional to the number of viable cells in mixtures of live and dead cells and correlate linearly with membrane integrity measurements made with cells that have been cultured for 24 h under various stressful conditions. 相似文献
70.
Kremastinou J Tzanakaki G Kansouzidou A Pagalis A Danielides V Kouppari G Lada E Kriz P Musilek M Weir DM Blackwell CC 《FEMS immunology and medical microbiology》1999,23(1):49-55
The number of cases of meningococcal disease reported to the Meningitis Reference Laboratory in Athens rose dramatically in 1996-1997. The aims were (1) to determine if the increase was due to introduction of new strains, (2) to assess the geographic and age distribution of the cases, (3) to compare antibiotic sensitivity patterns of the current isolates with strains from the early 1990s. In 1993-1994, 15/19 (74%) of the cases for which information on age was available were in children < or = 5 years; in 1995-1997, 80/179 (45%) of cases were in children < or = 5 years and 99 (55%) in the older age range (P < 0.02). From 593 cases in 1993 1997, 214 (36%) isolates were available for characterisation. Serogroup B was predominant in the early 1990s, but by 1997, serogroup C accounted for 46/72 (64%) of isolates and serogroup B for 25/72 (35%). Serogroup B was predominant in children < or = 5 years (44/78, 56%) but only 19/99 (18%) of older children and adults (P=0.0000005). Sulfonamide resistance decreased from 10/22 (45%) in 1993-1994 to 27/192 (14%) in 1995-1997 (P<0.01). Multilocus enzyme electrophoresis of 70 strains obtained during this period identified the epidemic ET-15 clone in 24 (34.3)%. The profiles of the Greek ET-15 isolates were identical to C:2a:P1.2(P1.5) strains responsible for the epidemic in the Czech Republic which began in 1993. This genotype was not found in Greek strains isolated prior to 1993. We conclude that the increase in meningococcal disease is due to introduction of the epidemic serogroup C:2a:P1.2(P1.5) strain responsible for disease in the Czech Republic and Canada. 相似文献