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   559篇
  免费   36篇
医药卫生   595篇
  2023年   3篇
  2021年   13篇
  2020年   10篇
  2019年   22篇
  2018年   16篇
  2017年   13篇
  2016年   13篇
  2015年   11篇
  2014年   16篇
  2013年   18篇
  2012年   25篇
  2011年   25篇
  2010年   17篇
  2009年   14篇
  2008年   17篇
  2007年   27篇
  2006年   25篇
  2005年   26篇
  2004年   21篇
  2003年   16篇
  2002年   24篇
  2001年   19篇
  2000年   24篇
  1999年   23篇
  1998年   4篇
  1997年   4篇
  1995年   8篇
  1993年   4篇
  1992年   12篇
  1991年   9篇
  1990年   9篇
  1989年   9篇
  1988年   6篇
  1987年   5篇
  1986年   6篇
  1985年   4篇
  1984年   4篇
  1983年   6篇
  1979年   6篇
  1978年   4篇
  1976年   5篇
  1975年   3篇
  1974年   6篇
  1973年   5篇
  1972年   5篇
  1971年   5篇
  1970年   3篇
  1969年   4篇
  1968年   2篇
  1967年   6篇
排序方式: 共有595条查询结果,搜索用时 15 毫秒
1.
Archives of Gynecology and Obstetrics - The objective of this study was to determine if high-dose antibiotic prophylaxis with cefazolin decreases the risk of surgical site infection (SSI) after a...  相似文献   
2.
Background and study aimsThe COVID-19 outbreak has reorganized surgical team conditions regarding endoscopy. The number of interventions has been reduced, the number of healthcare professionals must be limited, and both the patients and physicians are more protected than ever.Patients and MethodsIn the highest peak of contagion in Colombia, endoscopy, colonoscopy, and esophagogastroduodenoscopy were performed using a low-cost disposable device. A total of 1388 procedures were performed. Every patient was assessed for symptoms via a telephone call, at the health center, and after the procedure, following specific attention routes.ResultsAfter procedure follow-up, no positive cases of COVID-19 were noted.ConclusionThe methodology reduced the risk of infection during the COVID-19 pandemic.  相似文献   
3.
The chronic exposure of rats to a schedule of operant water reinforcement coupled with chronically restricted access to water sensitized the animals to intermittentd-amphetamine injections (0.31–2.5 mg/kg with intervals of 12–23 days between any two injections) in such a way that this drug came to produce catastrophic losses of body weight (32.4% of control levels). In the sessions whend-amphetamine was administered, the rats were also given a total of 12 brief electric shocks. Loss of body weight was unaccompanied by parallel changes in operant behavior performance, or in food or water intake. Remarkably, in other studies with the same interventions (sham schedule sessions, water deprivation, and foot shocks), with the exception that reinforcers were never delivered,d-amphetamine did not produce catastrophic falls in body weight. This super-reactivity tod-amphetamine toxicity may be mediated by a possible stressor action of the schedule of reinforcement. Its mechanism might be analogous to the known sensitization produced by classical experimental stressor stimuli to the repeated administration ofd-amphetamine.  相似文献   
4.
BHK 21 carrier cells persistently infected with VSV Indiana for over 2 years have been shedding generally very low levels of mature infectious virus or mature T particles (averaging less than one-hundredth p.f.u./cell/day) yet most cells are producing virus antigens and are resistant to homologous superinfection. However, large amounts of biologically active T particle RNP can be recovered from cytoplasmic extracts of these carrier cells even at times when they are shedding no detectable infectious virus. This recovered cytoplasmic RNP replicates (with helper B virions) to produce mature T particles, interferes strongly after DEAE dextran-facilitated uptake and, together with B virions, allows the establishment of a persistent carrier state in exposed cells. No 'provirus' DNA copies of the VSV RNA genome are detectable (less than 1/40 copy/cell or I copy per 40 cells) in carrier cells after more than 2 years of persistent infection, and all transfection attempts have failed using DNA from these VSV carriers or DNA from carrier cells persistently infected with some other negative strand RNA viruses (measles, mumps, LCM, influenza, rabies). Infectious viruses shed after more than I year from carrier cells originally infected with wild-type B virions are small plaque mutants showing a slight temperature sensitivity. Cured cell populations can be obtained from the long term VSV carrier culture by cloning in the presence or absence of antiviral antibody.  相似文献   
5.
Virus-induced RNA synthesis was studied in BHK 21 cells persistently infected with vesicular stomatitis virus (VSV) and rabies virus by labelling RNA synthesized in the presence of antinomycin D. During persistent infection the species of messenger RNA synthesized were similar in size and relative proportions to those seen during acute infection, but there were some minor differences. Full-sized B virion RNA was generally not detected during persistent infection, and new species (probably DI virion RNA) appeared.  相似文献   
6.
Systemic lupus erythematosus (SLE) is a complex autoimmune disease that exhibits extensive clinical heterogeneity. Several studies have suggested a role for tumor necrosis factor alpha (TNFalpha) in SLE and recently, the locus encompassing the TNF receptor II (TNFRII), which is a mediator of TNF effect, was amongst the candidate loci suggested by genetic linkage studies of multi-case SLE families. Komata et al. reported an association between a polymorphism at position 196 (R allele) of TNFR II and SLE in Japanese patients. We have typed SLE patients from two different ethnic populations, Spanish and UK Caucasoids, for this polymorphism using a polymerase chain reaction and restriction fragment length polymorphism (PCR-RFLP)-based technique. No significant differences in allele or genotype frequencies were found between cases and matched controls in either population. The TNFRII 196R allele does not appear to be associated with SLE susceptibility in either Spanish or UK populations.  相似文献   
7.
Occupational asthma caused by fish inhalation   总被引:1,自引:1,他引:1  
Occupational asthma (OA) due to fish inhalation, confirmed by specific bronchial challenge (SBC), has not been described as yet in medical literature, as far as we know. We describe two patients whose asthma was induced by occupational exposure to fish and confirmed by serial measurements of PEFR and SBC. Two fish-processing workers reported asthma symptoms related to their workplace. They were skin tested with fish extracts and their sera assayed for IgE antibodies to various fish species. Nonspecific bronchial reactivity was assessed by methacholine challenge. The occupational relationship was confirmed by PEFR monitoring in working and off-work periods. SBC with fish extracts was carried out to confirm the diagnosis of OA. Skin tests with raw and cooked plaice, salmon, hake, and tuna in patient 1 and anchovy, sardine, trout, salmon, Atlantic pomfret, and sole in patient 2 were positive. Specific IgE serum antibodies were found to salmon in patient 1 and to trout, anchovy, and salmon in patient 2. PEFR measurements differed significantly (P<0.001) between work and off-work periods for both patients. A bronchial challenge with methacholine was positive in patient 1. SBC with raw hake, salmon, plaice, and tuna extracts in patient 1 and raw salmon extract in patient 2 were all positive with an immediate response. SBC with Dermatophagoides pteronyssinus extract was entirely negative in both patients. In three asthmatic, non-fish-allergic controls, SBC with tuna, hake, salmon, and plaice were all negative. These results suggest that fish inhalation can elicit IgE-mediated occupational asthma.  相似文献   
8.
Enteroviruses are common pathogens of meningitis and encephalitis, and infections are often difficult to distinguish clinically from bacterial and herpetic infections of the central nervous system. An array of enteroviruses added to cerebrospinal fluid in reconstruction experiments were detected by a dot hybridization assay. Optimal handling and processing conditions for infected cerebrospinal fluid were established, and the effect on the hybridization reaction of humoral and cellular components of the inflammatory response was determined. Six hybridization probes, derived from poliovirus 1 and coxsackievirus B3, were then tested, singly and in combinations, to optimize the sensitivity and spectrum of the assay. Implications for enteroviral taxonomy based on these experiments are discussed.  相似文献   
9.
A functional hippocampus is required for trace fear conditioning, which involves learning the association of a tone and shock that are separated over time. Young and aged rats received 10 trace conditioning trials. Twenty-four hours later, rats were tested for fear to the tone in a novel chamber by measuring freezing. The results showed significantly lower levels of freezing in aged rats as compared with young rats, which provides evidence of age-related memory impairments. Pseudorandom conditioning groups showed low levels of freezing, indicative of no associative memory. Age-related memory deficits were not found with delay conditioning, which suggests no age-related sensory-motor deficits. These data suggest that aging hinders the ability of the hippocampus to process information separated over time.  相似文献   
10.
There is no US Food and Drug Administration (FDA) approved treatment for social phobia although data suggest efficacy for several drug classes, including beta-blockers, benzodiazepines, monoamine oxidase inhibitors, and selective serotonin reuptake inhibitors (SSRIs). The SSRIs are particularly attractive due to their favourable tolerance and safety profile. An open label trial of fluvoxamine was conducted to evaluate its efficacy and safety in the treatment of social phobia (DSM-III-R) and to assess physiological changes that may accompany treatment. Fifteen non-depressed patients, aged 22-44 years (mean 31.6 years), entered the study. A 5-min performance task (public speaking simulation) preceded and concluded the active treatment period. Cardiovascular monitoring was performed during this time and blood sampled for plasma cortisol and steady-state plasma fluvoxamine concentration (at week 7). Ten patients (5 men and 5 women) completed an active 6 week treatment period of flexible dosing (50-150 mg/day). Five patients failed to complete the study due to drowsiness (n = 2), nausea (n = 1), or were lost to follow-up (n = 2). Analysis of clinical ratings indicated a statistically significant decrease in all scales from baseline to week 7 at the conclusion of the active treatment period. Clinical benefits were still evident at follow-up 1 week after drug discontinuation. Neither physiological effects nor plasma drug concentration correlated with clinical change. Fluvoxamine appeared to be effective and well tolerated in completers. Randomized clinical trials are needed to further demonstrate the efficacy of fluvoxamine in the treatment of social phobia.  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