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   9172篇
  免费   655篇
  国内免费   20篇
耳鼻咽喉   103篇
儿科学   324篇
妇产科学   207篇
基础医学   1225篇
口腔科学   82篇
临床医学   1443篇
内科学   1787篇
皮肤病学   92篇
神经病学   878篇
特种医学   141篇
外科学   815篇
综合类   126篇
一般理论   15篇
预防医学   1079篇
眼科学   193篇
药学   609篇
中国医学   12篇
肿瘤学   716篇
  2023年   35篇
  2022年   61篇
  2021年   112篇
  2020年   103篇
  2019年   135篇
  2018年   153篇
  2017年   152篇
  2016年   147篇
  2015年   173篇
  2014年   247篇
  2013年   381篇
  2012年   569篇
  2011年   583篇
  2010年   352篇
  2009年   303篇
  2008年   574篇
  2007年   624篇
  2006年   626篇
  2005年   627篇
  2004年   564篇
  2003年   624篇
  2002年   564篇
  2001年   137篇
  2000年   143篇
  1999年   144篇
  1998年   127篇
  1997年   108篇
  1996年   93篇
  1995年   80篇
  1994年   77篇
  1993年   73篇
  1992年   88篇
  1991年   81篇
  1990年   70篇
  1989年   64篇
  1988年   68篇
  1987年   66篇
  1986年   46篇
  1985年   55篇
  1984年   61篇
  1983年   56篇
  1982年   36篇
  1981年   47篇
  1980年   33篇
  1979年   39篇
  1978年   33篇
  1977年   30篇
  1976年   41篇
  1975年   28篇
  1974年   27篇
排序方式: 共有9847条查询结果,搜索用时 15 毫秒
91.
BackgroundComplications and patient-reported outcomes (PROs) of total hip arthroplasty (THA) in patients with Legg-Calve-Perthes disease (LCPD) have demonstrated variable results. The purpose of this study was to use a validated grading scheme to analyze complications associated with THA in patients with residual LCPD deformities. Second, we report PROs and intermediate-term survivorship in this patient population.MethodsA retrospective, single-center review was performed on 61 hips in 61 patients who underwent THA for residual Perthes disease. Average patient age was 42 years and 26% of hips had previous surgery. Complications were determined and categorized using a validated grading scheme that included five grades based on the treatment required to manage the complication and on persistent disability. PROs were compared from preoperative to most recent follow-up time points.ResultsMajor complications (grade III) occurred in three patients (5%) which each required a second surgical intervention. The most common minor grade I or II complications (11.5%) were asymptomatic heterotopic ossification (3.3%). Patients were lengthened on the surgical side an average of 1.4 cm with no nerve palsies. All patient PROs improved from preoperative to postoperative time points with the modified Harris Hip Score improving from 46.9 preoperatively to 85.4 postoperatively (P < .01). Patients free from revision for any reason at final follow-up (5.6 years; range 2-13 years) was 98.4% with one patient needing a revision of their femoral component.ConclusionsTHA for the sequelae of the LCPD has an acceptable complication rate and provides excellent patient reported outcomes at mid-term follow-up.  相似文献   
92.
PurposeThe objective of this quality improvement (QI) initiative was to implement a standardized clinical treatment protocol for patients presenting with primary spontaneous pneumothorax (PSP) in order to decrease hospital length of stay (LOS), diagnostic radiation exposure, and related cost.MethodsBaseline data from patients admitted with PSP from January 1, 2016 to July 31, 2018 were compared to data from patients managed using a newly developed evidence-based treatment pathway from August 1, 2018 to December 31, 2019. Standard QI methodology was used to track results.ResultsFifty-six episodes of PSP were observed during the baseline period and 40 episodes of PSP following initiation of the PSP protocol. The average LOS decreased from 4.5 days to 2.9 days. Patients underwent an average of 8.8 X-rays per admission preintervention versus 5.9 postintervention. The rate of CT scans decreased from 45% to 15% (p = 0.002). There was no significant difference in the rates of 30-day recurrence between the preintervention (13%) and postintervention (10%) groups (p = 0.7). Average admission costs per patient decreased by $1322 after adoption of the pathway.ConclusionsAdoption of a standardized treatment protocol for PSP led to a reduction in LOS, diagnostic imaging utilization, and cost without increasing clinical recurrence.Type of studyQuality improvement.Level of evidenceLevel III.  相似文献   
93.
94.
Summary The results of the European Working Party for Hypertension in the Elderly Study showed that treatment of high blood pressure reduced the morbidity and mortality from strokes and myocardial infarction and reduced the incidence of heart failure in elderly patients. The largest number of hypertensive patients are elderly, and it is in this group of patients that the maximum benefit of treatment might be expected. The present study was designed to study in detail the efficacy and tolerability of ketanserin in an elderly population. Seventeen elderly (> 70 years) patients with a lying systolic blood pressure of 160 mmHg and/or a diastolic blood pressure of 90 mmHg were included in the study. For the 12 patients who completed the study, the mean blood pressure was significantly reduced on ketanserin compared with placebo (p<0.001) in the supine and erect positions. The mean net changes in blood pressure after 8 weeks were 21/17 mmHg and 23/16 mmHg erect. Heart rate was also significantly reduced (p<0.001) by a mean of 8 beats/min lying and 9 beats/min erect. Analysis of ambulatory 24-hour ECG tapes showed no significant effect of ketanserin on heart rhythms. Ketanserin therapy had no significant effect on routine hematology, plasma electrolytes, biochemistry, or urinalysis. Total exchangeable sodium and potassium and body weight were also unchanged. On ketanserin treatment, the overall quality of life score was significantly improved (p=0.002; analysis of variance on log transformed data) compared with the placebo phase.  相似文献   
95.
96.
Twenty soft contact lens wearers were fit with a high water content, non-HEMA (ofilcon A) lens (Durasoft 4; Wesley-Jessen) on the test eye. Patients subsequently wore one of the following four lenses on the same eye: a high-water content non-HEMA (surfilcon A) lens (Permaflex 74; CooperVision); a modified mid-water content HEMA (bufilcon A) lens (Hydrocurve Elite; Sola/Barnes-Hind); a low-water content HEMA (polymacon) lens (O4; Bausch & Lomb); or a low-water content non-HEMA (crofilcon A) lens (CSI; Sola/Barnes-Hind). All lenses were worn on a daily wear basis for one month and then evaluated with the scanning electron microscope (SEM). The amount of surface deposition was measured in terms of the area of lens covered by deposit as visualized on a standard series of SEM photographs. When control was obtained for patient, eye, technique, care system, and wearing time, similar amounts of deposit were found on the two high water content soft lenses. A significantly greater amount of deposit was found on the non-HEMA high water content ofilcon A lens compared to the mid-water content modified HEMA material. However, when the patient's tendency to produce "heavy" or "light" deposits on a soft lens surface is taken into account, then for the lighter depositors the high water content non-HEMA material was found to be as acceptable as the low water content HEMA and non-HEMA materials. But for heavy depositors the high water content non-HEMA material is not recommended.  相似文献   
97.
PEG (percutaneous endoscopic gastrostomy) tubes are frequently placed in nursing home patients. The aim of this study was to assess retrospectively the long-term changes in functional and nutritional statuses, tube-related complications, and factors influencing survival in 46 nursing home residents, mean age 73.6 years (range 19–96). Functional status was evaluated by a standard rehabilitation medicine scale. Nutritional status was evaluated by serum albumin and cholesterol concentrations and by weight. PEG-related complications requiring hospitalization or emergency room or clinic evaluations were noted. Additionally, changes in resuscitation status were noted. The predominant indication for PEG placement was dementia (52%). At PEG placement, 48% of patients had total functional impairment. Regardless of the severity of impairment, no patient's functional status improved after PEG. Nutritional status did not improve significantly. Mortality approached 50% and 60% at 12 and 18 months, respectively, and was significantly related to age, resuscitation status, and serum albumin concentration. All patients under 40 years of age at PEG survived, in contrast to 41.3% of patients over 40 years of age (P<0.001). Sixty-three percent of patients who were full code at PEG placement survived, in contrast to 10% of no code patients (P<0.001). Albumin 3.5 g/dl at PEG or thereafter was associated with improved survival (P<0.001) as compared to albumin <3.5 g/dl. PEG-related complications occurred in 34.7% of patients, and the first occurred four months after PEG. We conclude that realistic expectations of what PEG can accomplish be a factor in the decision to place a PEG tube in nursing home patients.  相似文献   
98.
The purpose of this study was to compare neutrophil cidal activity during general or spinal anaesthesia. Assays were performed on neutrophils extracted from the blood of patients after surgery had been under way for one hour. First, the ability of the neutrophils to kill a standard laboratory strain of S. aureus was examined. Neutrophils extracted from the blood during surgery in the spinal anaesthetic group and incubated with the staphylococci for one hour killed twice as many bacteria than those from two groups of patients that received halothane or isoflurane general anaesthesia (P < 0.05). This effect persisted, to a lesser extent, in the spinal group neutrophils after two hours of incubation with the bacteria. Second, neutrophils from patients under the same conditions of surgery and anaesthesia were tested to examine the effect of the different anaesthetic techniques on neutrophil biocidal mechanisms. Neutrophils extracted during surgery in the spinal group released more superoxide in response to phorbol-12-myristate-13-acetate (PMA) than those from both groups of patients that received general anaesthesia (P < 0.05). It is concluded that there is an increased state of reactivity of the neutrophil cell membrane NADPH oxidase system in patients receiving spinal anaesthesia than in patients receiving general anaesthesia.  相似文献   
99.
The relationship of serotonin (5-HT) receptors to the action of the experimental antitumour drugs flavone-8-acetic acid (FAA) and 5,6-dimethylxanthenone-4-acetic acid (5,6-MeXAA) was studied. Both FAA and 5,6-MeXAA are known to induce the synthesis of tumour necrosis factor- (TNF) and to stimulate nitric oxide synthesis in vivo, as measured by elevation of plasma nitrate. Serotonin potentiated the effect of a subtherapeutic dose of 5,6-MeXAA (20 mg/kg) as measured both by plasma nitrate increase and by growth delay of s.c. implanted colon 38 tumours. On the other hand, administration of the serotonin 5-hydroxytryptamine-2 (T-HT2) antagonist cyproheptadine (20 mg/kg) inhibited both the plasma nitrate response and, to a lesser extent, the induction of tumour haemorrhagic necrosis by 5,6-MeXAA, FAA and TNF. Reduction of circulating plasma serotonin by pre-treatment withp-chlorophenylalanine and reserpine reduced the plasma nitrate response, but not the tumour necrosis response, to 5,6-MeXAA (30 mg/kg). It is suggested that serotonin is necessary for the induction of nitric oxide synthases and acts, either directly or indirectly, in concert with TNF. Serotonin agonists may have utility in increasing nitric oxide synthesis in response to TNF or to agents that induced TNF as part of their antitumour action.This research was supported by the Auckland Division of Cancer Society of New Zealand and the Health Research Council of New Zealand, by the Health Research Council of New Zealand and by the Ruth Spencer Medical Research Fellowship Trust.  相似文献   
100.
This article deals with some of the recent evidence bearing on the issues of the liability of benzodiazepines to lead to abuse, dependence, and adverse behavioral effects. Reviews of epidemiological, clinical and experimental literature indicated that the previous conclusion about abuse of these drugs still holds: the vast majority of the use of benzodiazepines is appropriate. Problems of nonmedical use arise nearly exclusively among people who abuse other drugs. Nevertheless, there are reasons for concern about patients who take benzodiazepines regularly for long periods of time. These drugs can produce physiological dependence when taken chronicaly, and although this does not appear to result in dose escalation or other evidence of psychological dependence, physiological dependence can result in patient discomfort if drug use is abruptly discontiniued. Also, physicians are currently prescribing shorter-acting benzodiazepines in preference to longer-acting benzodiazepines. The shorter-acting drugs can produce a more intense withdrawal syndrome following chronic administration. Furthermore, rates of use of benzodiazepines increase with age, and elderly patients are more likely than younger ones to take the drug chronically. The clearest adverse effect of benzodiazepines is impairment of memory. This, too, may be particular concern in older patients whose recall in the absence of drug is typically impaired relative to younger individuals, and who are more compromised following drug administration.This article was supported by USPHS Grant DA-00254 and by funding from Hoffmann-La Roche, Inc.  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