首页 | 本学科首页   官方微博 | 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   1552篇
  免费   120篇
  国内免费   8篇
耳鼻咽喉   8篇
儿科学   33篇
妇产科学   38篇
基础医学   353篇
口腔科学   6篇
临床医学   167篇
内科学   281篇
皮肤病学   25篇
神经病学   170篇
特种医学   39篇
外科学   130篇
综合类   5篇
预防医学   163篇
眼科学   22篇
药学   127篇
中国医学   8篇
肿瘤学   105篇
  2023年   6篇
  2022年   14篇
  2021年   40篇
  2020年   28篇
  2019年   30篇
  2018年   47篇
  2017年   24篇
  2016年   34篇
  2015年   38篇
  2014年   43篇
  2013年   68篇
  2012年   124篇
  2011年   122篇
  2010年   91篇
  2009年   72篇
  2008年   85篇
  2007年   111篇
  2006年   103篇
  2005年   111篇
  2004年   87篇
  2003年   86篇
  2002年   93篇
  2001年   17篇
  2000年   13篇
  1999年   18篇
  1998年   25篇
  1997年   23篇
  1996年   19篇
  1995年   10篇
  1994年   8篇
  1993年   14篇
  1992年   8篇
  1991年   6篇
  1990年   5篇
  1988年   5篇
  1987年   4篇
  1986年   6篇
  1985年   6篇
  1984年   4篇
  1983年   3篇
  1982年   4篇
  1981年   2篇
  1980年   7篇
  1979年   1篇
  1977年   3篇
  1976年   1篇
  1975年   1篇
  1974年   2篇
  1973年   5篇
  1971年   1篇
排序方式: 共有1680条查询结果,搜索用时 15 毫秒
131.
The major potential adverse effect of use of sulfonylurea agents (SUAs) is a hyperinsulinaemic state that causes hypoglycaemia. It may be observed during chronic therapeutic dosing, even with very low doses of a SUA, and especially in older patients. It may also result from accidental or intentional poisoning in both diabetic and nondiabetic patients. The traditional approach to SUA-induced hypoglycaemia includes administration of glucose, and glucagon or diazoxide in those who remain hypoglycaemic despite repeated or continuous glucose supplementation. However, these antidotal approaches are associated with several shortcomings, including further exacerbation of insulin release by glucose and glucagon, leading only to a temporary beneficial effect and later relapse into hypoglycaemia, as well as the adverse effects of both glucagon and diazoxide. Octreotide inhibits the secretion of several neuropeptides, including insulin, and has successfully been used to control life-threatening hypoglycaemia caused by insulinoma or persistent hyperinsulinaemic hypoglycaemia of infancy. Therefore, this agent should in theory also be useful to decrease glucose requirements and the number of hypoglycaemic episodes in patients with SUA-induced hypoglycaemia. This has apparently been confirmed by experimental data, one retrospective study based on chart review, and several anecdotal case reports. There is thus a need for further prospective studies, which should be adequately powered, randomized and controlled, to confirm the probable beneficial effect of octreotide in this setting.  相似文献   
132.
133.
134.
For the first time we have investigated the natural ecosystem engineering capacity of stromatolitic microbial assemblages. Stromatolites are laminated sedimentary structures formed by microbial activity and are considered to have dominated the shallows of the Precambrian oceans. Their fossilised remains are the most ancient unambiguous record of early life on earth. Stromatolites can therefore be considered as the first recognisable ecosystems on the planet. However, while many discussions have taken place over their structure and form, we have very little information on their functional ecology and how such assemblages persisted despite strong eternal forcing from wind and waves. The capture and binding of sediment is clearly a critical feature for the formation and persistence of stromatolite assemblages. Here, we investigated the ecosystem engineering capacity of stromatolitic microbial assemblages with respect to their ability to stabilise sediment using material from one of the few remaining living stromatolite systems (Highborne Cay, Bahamas). It was shown that the most effective assemblages could produce a rapid (12–24 h) and significant increase in sediment stability that continued in a linear fashion over the period of the experimentation (228 h). Importantly, it was also found that light was required for the assemblages to produce this stabilisation effect and that removal of assemblage into darkness could lead to a partial reversal of the stabilisation. This was attributed to the breakdown of extracellular polymeric substances under anaerobic conditions. These data were supported by microelectrode profiling of oxygen and calcium. The structure of the assemblages as they formed was visualised by low-temperature scanning electron microscopy and confocal laser microscopy. These results have implications for the understanding of early stromatolite development and highlight the potential importance of the evolution of photosynthesis in the mat forming process. The evolution of photosynthesis may have provided an important advance for the niche construction activity of microbial systems and the formation and persistence of the stromatolites which came to dominate shallow coastal environments for 80% of the biotic history of the earth.  相似文献   
135.
Palmitoylethanolamide (PEA) is an endogenous lipid mediator known to reduce pain and inflammation. However, only limited clinical studies have evaluated the effects of PEA in neuroinflammatory and neurodegenerative diseases. Multiple sclerosis (MS) is a chronic autoimmune and inflammatory disease of the central nervous system. Although subcutaneous administration of interferon (IFN)-β1a is approved as first-line therapy for the treatment of relapsing–remitting MS (RR-MS), its commonly reported adverse events (AEs) such as pain, myalgia, and erythema at the injection site, deeply affect the quality of life (QoL) of patients with MS. In this randomized, double-blind, placebo-controlled study, we tested the effect of ultramicronized PEA (um-PEA) added to IFN-β1a in the treatment of clinically defined RR-MS. The primary objectives were to estimate whether, with um-PEA treatment, patients with MS perceived an improvement in pain and a decrease of the erythema width at the IFN-β1a injection site in addition to an improvement in their QoL. The secondary objectives were to evaluate the effects of um-PEA on circulating interferon-γ, tumor necrosis factor-α, and interleukin-17 serum levels, N-acylethanolamine plasma levels, Expanded Disability Status Scale (EDSS) progression, and safety and tolerability after 1 year of treatment. Patients with MS receiving um-PEA perceived an improvement in pain sensation without a reduction of the erythema at the injection site. A significant improvement in QoL was observed. No significant difference was reported in EDSS score, and um-PEA was well tolerated. We found a significant increase of palmitoylethanolamide, anandamide and oleoylethanolamide plasma levels, and a significant reduction of interferon-γ, tumor necrosis factor-α, and interleukin-17 serum profile compared with the placebo group. Our results suggest that um-PEA may be considered as an appropriate add-on therapy for the treatment of IFN-β1a-related adverse effects in RR-MS.  相似文献   
136.
OBJECTIVE: To analyze the effects of an extracorporeal bioartificial liver containing alginate bead-entrapped hepatocytes on pigs with ischemia-induced acute hepatic failure. DESIGN: Prospective animal study. SETTING: University and INSERM laboratory. SUBJECTS: Fifteen Large White/Pietrin female pigs weighing 20-30 kg. INTERVENTIONS: Acute hepatic failure was induced by end-to-side portocaval shunt and ligature of the whole porta hepatitis. The bioartificial liver was in a thermostabilized column, containing a fluidized bed of alginate beads that embedded porcine hepatocytes, connected to a plasmapheresis system. Intracranial pressure; survival; ammonia, total bilirubin, aminotransferases, alkaline phosphatase, and lactate concentrations; and clotting factors were studied. The groups were pigs with acute hepatic failure (group 1, n = 4), pigs with acute hepatic failure treated with bioartificial liver containing empty beads (group 2, n = 4), or porcine hepatocytes (group 3, n = 5). MEASUREMENTS AND MAIN RESULTS: In group 1, survival of pigs averaged 10.9 +/- 1.0 hrs; intracranial pressure reached 32.3 +/- 3.8 mm Hg and was associated with coma and cerebral edema. After connection to the bioartificial liver, the survival of acute hepatic failure pigs was 12.1 +/- 1.4 hrs in group 2 and 14.8 +/- 2.5 hrs in group 3. In group 3, intracranial pressure and bilirubin concentrations were reduced significantly compared with both group 1 and group 2. Neither signs of encephalopathy nor cerebral edema was observed in any animal of group 3. In all animals, plasma ammonium, aminotransferases, alkaline phosphatase, and lactate concentrations increased and clotting factors decreased with no significant differences between the three groups. Autopsy revealed a total necrosis of the liver, which was histologically confirmed. CONCLUSIONS: The ischemia-induced model of acute hepatic failure in pigs is reproducible and provides measurable clinical and biological features. A bioartificial liver containing alginate bead-entrapped hepatocytes improves the signs of encephalopathy in pigs with ischemia-induced acute hepatic failure, suggesting that the bioartificial liver can clear out toxic compounds that are released from necrotic livers.  相似文献   
137.
138.
Purpose. To describe the level of functioning of adolescents and young adults with cerebral palsy (CP) and study determinants of their level of functioning.

Method. In the CP Transition study, adolescents and young adults aged 16 - 20 years, diagnosed with CP without severe learning disabilities (n = 103) participated. In this group we assessed subject characteristics, i.e., age, type of CP, gross motor function (GMFCS), level of education as well as outcome measures on functioning in daily activities and social participation (Life Habits questionnaire, Vineland Adaptive Behavior Scale, Functional Independence Measure). Multivariate regression analyses were performed.

Results. About 20 - 30% of the participants encountered restrictions in daily activities (mobility, self-care, nutrition) and social participation (taking responsibility, community living, leisure activities and employment). The GMFCS level, level of education, and age proved to be important determinants of functioning in daily activities and social participation, explaining 70% and 66% of the variance in outcome respectively.

Conclusion. A significant number of adolescents and young adults with CP without severe learning disabilities are restricted in daily activities and social participation. These problems are mainly attributable to restricted gross motor functioning, a low level of education and younger age.  相似文献   
139.
In most effectiveness studies on lumbar supports for patients with low back pain, insufficient data are reported about adherence. In a secondary preventive RCT, we found beneficial effects and a good adherence among home care workers with low back pain. To target the use of lumbar supports on those patients who can benefit optimally from usage, we need to know why people are adherent. We used the attitude, social support and self-efficacy model to identify determinants for prolonged adherence to wearing a lumbar support. The strongest predictor for intending sustained use of a lumbar support was a positive attitude towards lumbar supports, explaining 41% of the variance (B = 1.31; p < 0.001). Social support and self-efficacy played a minor role. The intention for prolonged use of a lumbar support for workers with recurrent back pain was mainly explained by a positive attitude. The discomfort of a lumbar support was outweighed by perceived benefit.  相似文献   
140.
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