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   5989篇
  免费   539篇
  国内免费   8篇
耳鼻咽喉   73篇
儿科学   181篇
妇产科学   95篇
基础医学   623篇
口腔科学   80篇
临床医学   633篇
内科学   887篇
皮肤病学   48篇
神经病学   513篇
特种医学   299篇
外科学   1027篇
综合类   118篇
一般理论   7篇
预防医学   896篇
眼科学   136篇
药学   356篇
中国医学   9篇
肿瘤学   555篇
  2022年   41篇
  2021年   81篇
  2020年   47篇
  2019年   80篇
  2018年   96篇
  2017年   84篇
  2016年   86篇
  2015年   85篇
  2014年   140篇
  2013年   189篇
  2012年   335篇
  2011年   351篇
  2010年   217篇
  2009年   169篇
  2008年   270篇
  2007年   320篇
  2006年   362篇
  2005年   316篇
  2004年   298篇
  2003年   260篇
  2002年   241篇
  2001年   159篇
  2000年   182篇
  1999年   106篇
  1998年   72篇
  1997年   59篇
  1996年   44篇
  1995年   38篇
  1994年   54篇
  1993年   43篇
  1992年   136篇
  1991年   103篇
  1990年   117篇
  1989年   115篇
  1988年   108篇
  1987年   95篇
  1986年   80篇
  1985年   77篇
  1984年   74篇
  1983年   50篇
  1982年   37篇
  1981年   37篇
  1980年   38篇
  1979年   59篇
  1977年   39篇
  1976年   39篇
  1975年   37篇
  1973年   38篇
  1972年   41篇
  1966年   34篇
排序方式: 共有6536条查询结果,搜索用时 15 毫秒
61.
For a quality management transformation to occur, a healthcare organization must focus on education and development, performance management, and recognition and reward systems during the first years of implementation. Education and development are perhaps the most important human resource management functions when implementing quality management principles and processes because behavioral changes will be required at all organizational levels. Specific programs that support an organization's quality management effort will vary but should include the conceptual, cultural, and technical aspects of quality management. The essence of quality management is to always satisfy the customer and to continuously improve the services and products the organization offers. The approach to performance management should therefore rely on customer feedback and satisfaction. An organization committed to quality management should base its performance management approach on customer orientation, process improvement, employee involvement, decision making with data, and continuous improvement. Managers and trustees are being challenged to provide innovative recognition and reward systems that reinforce the values and behaviors consistent with quality management. Such systems must also be aligned with the behaviors and outcomes that support the philosophy, mission, and values of the Catholic healthcare ministry. The following components should be considered for a recognition and reward system: base pay, incentives, benefits, and nonmonetary rewards.  相似文献   
62.
63.
This study was prompted by our incomplete understanding of the mechanism responsible for the clinical benefits of pharmacological doses of thiamin in some patients with maple syrup urine disease (MSUD) and the question of whether thiamin diphosphate (TDP), a potent inhibitor of the activity of the protein kinase that phosphorylates and inactivates the isolated branched-chain alpha-ketoacid dehydrogenase (BCKDH) complex, affects the activity state of the complex. Rats were fed a chemically-defined diet containing graded levels of thiamin (0, 0.275, 0.55, 5.5, and 55 mg thiamin/kg diet). Maximal weight gain was attained over a 3-wk period only in rats fed diets with 5.5 and 55 mg thiamin/kg. Feeding rats the thiamin-free diet for just 2 d caused loss of nearly half of the TDP from liver mitochondria. Three more days caused over 70% loss, an additional 3 wk, over 90%. Starvation for 2 d had no effect, suggesting a mechanism for conservation of TDP in this nutritional state. Mitochondrial TDP was higher in rats fed pharmacological amounts of thiamin (55 mg thiamin/kg diet) than in rats fed adequate thiamin for maximal growth. Varying dietary thiamin had marked but opposite effects on the activities of alpha-ketoglutarate dehydrogenase (alpha-KGDH) and BCKDH. Thiamin deficiency decreased alpha-KGDH activity, increased BCKDH activity, and increased the proportion of BCKDH in the active, dephosphorylated, state. Excess dietary thiamin had the opposite effects. TDP appears to be more tightly associated with alpha-KGDH than BCKDH in thiamin-deficient rats, perhaps denoting retention of alpha-KGDH activity at the expense of BCKDH activity. Thus, thiamin deficiency and excess cause large changes in mitochondrial TDP levels that have a major influence on the activities of the keto acid dehydrogenase complexes.  相似文献   
64.
PURPOSE: The purpose of this study was to document the presence of secondary injury in skeletal muscle, to quantify it, and to determine whether it is altered by acute cryotherapy. METHODS: Crush injuries to the triceps surae of 19 adult male Sprague-Dawley rats were either treated continuously with ice for 5 h (N = 10) or received no ice treatment (N = 9). After treatment, tissues were assayed for the reduction of triphenyltetrazolium chloride (TTC) to triphenylformazan (formazan red). TTC reduction is indicative of oxidative function and serves as an indicator of cellular damage. RESULTS: A significantly lower TTC reduction rate was seen in both cold-treated injured tissue (6.59 +/- 1.01 microg x mg(-1) x h(-1)) and nontreated injured tissue (4.48 +/- 0.79 microg x mg(-1) x h(-1)) compared with uninjured controls (ice group = 7.94 +/- 1.49 microg x mg(-1) x h(-1), no-ice group = 6.62 +/- 0.75 microg x mg(-1) x h(-1)). These data indicate that crushing of muscle tissue produces injury measurable with the TTC reduction assay. Additionally, in crush-injured tissues, a significantly lower TTC reduction rate was seen in untreated tissues (4.48 +/- 0.79 microg x mg(-1) x h(-1)) compared with ice treated tissues (6.59 +/- 1.01 microg x mg(-1) x h(-1)), indicating that cryotherapy reduces the magnitude of secondary injury. CONCLUSIONS: From these data, it can be concluded that secondary injury occurs after primary crush injury and that secondary injury is retarded by acute treatment with 5 h of continuous cryotherapy.  相似文献   
65.
BACKGROUND: A survey of pediatric cardiac surgeons was performed to establish current opinions in the United Kingdom concerning closure of ventricular septal defect. METHODS: Questionnaires were sent to 14 pediatric cardiac centers in 1995 (16 surgeons, 100% response), and again in 1997 (20 surgeons, 100% response). RESULTS: Results are presented for 1997, with findings from 1995 shown in parentheses. Eleven (6) surgeons used bypass exclusively, 9 (10) sometimes used circulatory arrest. Operative techniques were similar, although the material used for the patch varied. Multiple defects were approached via the transatrial route by 18 (15), right ventriculotomy by 11 (7) and left ventriculotomy by 7 (6). The juxta-arterial defect was approached via the transpulmonary route by 16 (13), a combination by 9 (11), transatrial by 10 (6), and transventricular by 9 (5). The most common indications for pulmonary arterial banding were "Swiss cheese" defect for 13 (13), and functionally single ventricle for 5 (6). Ventricular septal defect associated with coarctation was repaired in two stages by 13 (10), a single stage by 5 (3), or either by 1 (3). CONCLUSIONS: Pediatric cardiac surgeons in the United Kingdom demonstrate a uniform, evidence-based approach to the management of ventricular septal defect.  相似文献   
66.
PURPOSE: The purposes of this study were to 1) assess the prevalence of clustering of metabolic markers of the MS in a defined population and 2) determine the association between CRF and such clustering in a large group of adult men (N = 15,537) and women (N = 3,899). METHODS: Metabolic markers of the MS included systolic blood pressure (BP) > or = 140 mm Hg, serum triglycerides > or = 150 mg x dL(-1), fasting blood glucose > or = 110 mg x dL(-1), and elevated central adiposity (waist circumference > 100 cm). Cardiorespiratory fitness was defined as total time on a maximal treadmill exercise test. The cohort was grouped by the number of metabolic abnormalities and level of CRF. Associations between CRF and the number of metabolic abnormalities were assessed using proportional odds logit models. RESULTS: Among men, the age-adjusted cumulative odds ratio for abnormal markers of the MS was 3.0 (95% C.I. 2.7-3.4; P < 0.001) for the least-fit men when compared with moderately-fit ones, and 10.1 (95% C.I. 9.1-11.2; P < 0.001) when compared with the most-fit men. Among women, the age-adjusted cumulative odds ratio was 2.7 (95% C.I. 2.1-3.5; P < 0.001) for the least-fit women when compared with moderately-fit ones, and 4.9 (95% C.I. 3.8-6.3; P < 0.001) when compared with the most-fit women. CONCLUSIONS: These cross-sectional results suggest that low CRF is associated with an increased clustering of the metabolic abnormalities associated with the MS in both adult men and women and support the need for future prospective analyses.  相似文献   
67.
BACKGROUND: Action research has been used successfully to promote change in disciplines other than medicine, but there are few examples of its use in primary care. OBJECTIVE: We aimed to discuss the benefits and difficulties of using action research in primary care using the example of child health surveillance provision in general practice. METHODS: Twenty-eight general practices were randomly allocated into two groups. Action research was used to promote change in 14 practices by facilitating practice meetings and by providing written feedback. The other 14 practices received written feedback alone. The two groups of practices were compared using the following: (i) semi-structured interviews with one health visitor and GP from each practice; (ii) observation of baby clinics; (iii) questionnaires to parents; and (iv) return rates of child health surveillance reviews from the personal child health record. RESULTS: All 14 practices in the action research arm of the study met as individual practice teams and decided to make changes to their provision of child health surveillance. Ten practices audited their child health surveillance as a result. More health visitors in the action research practices than in the comparison practices reported changes to child health surveillance, audit, communication and use of the personal child health record. The majority of health visitors and GPs thought involvement in the action research process was beneficial. However, we were unable to show a statistically significant difference between the two groups of practices in baby clinic provision, parent satisfaction or the return rate of child health surveillance reviews. CONCLUSION: Our study suggests that action research is a successful method of promoting change in primary care. However, measuring the impact of change is difficult.  相似文献   
68.
69.
Rationale: Facial expressions appear to be processed by at least partially separable neuro-cognitive systems. Given this functional specialisation of expression processing, it is plausible that these neurocognitive systems may also be dissociable pharmacologically. Objective: The present study therefore compared the effects of diazepam (15 mg) with placebo upon the ability to recognise emotional expressions. Methods: A double blind, independent group design was used to compare the effects of diazepam and matched placebo in32 healthy volunteers. Participants were presented morphed facial expression stimuli following a paradigm developed for use with patients with brain damage and asked to name one of the six basic emotions (sadness, happiness, anger, disgust, fear and surprise). Results: Diazepam selectively impaired subjects’ ability to recognise angry expressions but did not affect recognition of any other emotional expression. Conclusions: The findings are interpreted as providing further support for the suggestion that there are dissociable systems responsible for processing emotional expressions. It is suggested that these findings may have implications for understanding paradoxical aggression sometimes elicited by benzodiazepines. Received: 27 May 1999 / Accepted: 7 July 1999  相似文献   
70.

Purpose

To investigate if pre-block iv sedation using midazolam, alfentanil, or a midazolam-alfentanil combination minimizes pain, reduces pain recall, and attenuates haemodynamic responses to peribulbar block; and to determine other factors influencing oxygen saturation (SpO2) following iv sedation.

Methods

In a randomized, double-blind, placebo-controlled study, 120 patients, mean age 73 yr, having cataract surgery with peribulbar anaesthesia, were randomized to receive either normal saline, 1 mg midazolam, 500 μg alfentanil, or 0.5 mg midazolam plus 250 μg alfentanil. Blood pressure (BP), heart rate (HR) and pulse oximetry readings were recorded before injection of the study drugs, immediately after completion of the peribulbar block, and 10 min after the block. Pain from the anaesthetic block was assessed immediately after the block and after surgery using a visual analog scale, and recall of pain was assessed by telephone on the day after surgery.

Results

Pain scores were low in all four groups. Midazolamalfentanil reduced pain perception, and all iv sedation used reduced pain recall. Midazolam reduced systolic BP; alfentanil ± midazolam reduced HR. All iv sedation reduced SpO2 more than did saline, but not usually to a clinically important level. Nine patients had a SpO2 S 90%; all had received alfentanil with or without midazolam. It was not possible to predicoxygen saturation levels by any factors other than iv sedation and baseline SpO2 levels.

Conclusion

Intravenous sedation with midazolam or alfentanil or in combination reduced pain perception, pain recall, and haemodynamic responses from peribulbar anaesthesia. Fifteen percent of patients given alfentanil developed clinically important oxygen desaturation. The use of fine gauge needles combined with slow injection of anaesthetic solution causes minimal discomfort, and routine iv sedation may be unnecessary.  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