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   1369篇
  免费   75篇
  国内免费   21篇
耳鼻咽喉   11篇
儿科学   41篇
妇产科学   14篇
基础医学   101篇
口腔科学   88篇
临床医学   190篇
内科学   286篇
皮肤病学   5篇
神经病学   82篇
特种医学   242篇
外国民族医学   1篇
外科学   108篇
综合类   35篇
预防医学   116篇
眼科学   5篇
药学   50篇
肿瘤学   90篇
  2022年   11篇
  2021年   25篇
  2019年   14篇
  2018年   15篇
  2017年   14篇
  2016年   25篇
  2015年   18篇
  2014年   42篇
  2013年   68篇
  2012年   40篇
  2011年   55篇
  2010年   45篇
  2009年   59篇
  2008年   42篇
  2007年   44篇
  2006年   30篇
  2005年   35篇
  2004年   25篇
  2003年   20篇
  2002年   23篇
  2001年   20篇
  2000年   28篇
  1999年   25篇
  1998年   42篇
  1997年   42篇
  1996年   41篇
  1995年   40篇
  1994年   27篇
  1993年   25篇
  1992年   16篇
  1991年   19篇
  1990年   18篇
  1989年   42篇
  1988年   33篇
  1987年   23篇
  1986年   20篇
  1985年   40篇
  1984年   25篇
  1983年   20篇
  1982年   23篇
  1981年   21篇
  1980年   20篇
  1979年   13篇
  1978年   22篇
  1977年   22篇
  1976年   13篇
  1974年   13篇
  1971年   10篇
  1968年   10篇
  1967年   10篇
排序方式: 共有1465条查询结果,搜索用时 15 毫秒
41.
STUDY OBJECTIVE: The purpose of this study is to determine the efficacy and safety of sedation/analgesia using a mixture of propofol, alfentanil, and lidocaine. DESIGN: A retrospective case review was undertaken. SETTING: This study took place at a university medical center. PATIENTS: Eighty-nine American Society of Anesthesiologists physical status 1, 2, and 3 adult patients undergoing ophthalmic surgery with regional block and monitored anesthesia care were studied. INTERVENTION: Six milliliters of propofol, 2 mL of alfentanil, and 2 mL of 2% lidocaine (6-2-2 mixture) were freshly mixed. The bolus dose was determined based on the patients' age: 5 microg/kg of alfentanil (and 0.3 mg/kg of propofol) for patients older than 75 years; the dose increased 1 mug/kg per 10-year decrease in age; and up to 9 microg/kg of alfentanil (0.54 mg/kg of propofol) for patients younger than 45 years. Regional block was performed at 1 minute after bolus completion. Blood pressure (BP), Sa(O2), electrocardiogram, capnography, clinical signs of sedation, responses to block, need for airway support, nausea and vomiting (N/V), pain due to propofol infusion, recall, and patient and surgeon satisfaction were recorded. MEASUREMENTS AND MAIN RESULTS: Seventy-eight percent of patients achieved analgesia and sedation without adverse response to the block. Twelve percent achieved good analgesia and sedation with only eyebrow movement upon needle insertion. Twenty-seven percent had respiratory depression but were able to follow commands and maintain adequate ventilation. Two percent had brief apnea alleviated by chin lift or jaw thrust. None had pain because of propofol infusion or N/V. Before sedation, average systolic BP was significantly increased (P < 0.0001) compared with baseline. After sedation and block, systolic BP decreased 6% from baseline (P < 0.005). CONCLUSION: Adjusted for age and weight, the dose of the 6-2-2 mixture met the sedation requirements for most patients. With a low incidence of need for airway support, no pain during infusion, and no N/V, this novel mixture of propofol, alfentanil, and lidocaine provided adequate analgesia and sedation as well as hemodynamic stability for ophthalmic surgery under regional block.  相似文献   
42.
PurposeTo describe in detail British Columbia (BC) Cancer Agency (BCCA) Provincial Prostate Brachytherapy (PB) Quality Assurance (QA) Program.Methods and MaterialsThe BCCA PB Program was established in 1997. It operates as one system, unified and supported by electronic and information systems, making it a single PB treatment provider for province of BC and Yukon. To date, >4000 patients have received PB (450 implants in 2011), making it the largest program in Canada. The Program maintains a large provincial prospective electronic database with records on all patients, including disease characteristics, risk stratification, pathology, preplan and postimplant dosimetric data, follow-up of prostate-specific antigen, and toxicity outcomes.ResultsQA was an integral part of the program since its inception. A formal QA Program was established in 2002, with key components that include: unified eligibility criteria and planning system, comprehensive database, physics and oncologist training and mentorship programs, peer review process, individual performance outcomes and feedback process, structured continuing education and routine assessment of the program's dosimetry, toxicity and prostate-specific antigen outcomes, administration and program leadership that promotes a strong culture of patient safety. The emphasis on creating a robust, broad-based network of skilled providers has been achieved by the program's requirements for training, education, and the QA process.ConclusionsThe formal QA process is considered a key factor for the success of cancer control outcomes achieved at BCCA. Although this QA model may not be wholly transferable to all PB programs, some of its key components may be applicable to other programs to ensure quality in PB and patient safety.  相似文献   
43.
The authors studied the impact of edge enhancement and gray scale polarity reversal on the detection of subtle lung cancers. Three experienced readers reviewed 46 biopsy-proved subtle lung cancers and 46 normal controls on chest radiographs that had been digitized into a 1,024 X 1,536-pixel matrix 8 bits deep. Receiver-operating characteristics (ROC) analysis of 1,656 pooled observations indicated that performance was best with the unmodified images (ROC area = 0.83), degraded by moderate enhancement of medium frequencies (ROC area = 0.80), and markedly impaired by severe enhancement of low frequencies (ROC area = 0.69). Gray scale polarity reversal further degraded performance (unenhanced ROC area = 0.74; moderately enhanced ROC area = 0.76; severely enhanced ROC area = 0.76). The authors conclude that edge enhancement and gray scale polarity reversal can impair the detectability of subtle lung cancers on digitized radiographs of medium resolution.  相似文献   
44.
The failure to identify specific non-shared environmental influences on behavior coupled with the belief that shared environmental factors contribute minimally to individual differences in behavior has led to the concern that major environmental determinants of behavior may be idiosyncratic, and therefore undetectable. We used data on adoptive (N = 246) and biologically related (N = 130) same-sex sibling pairs (mean ages = 16.1 years older sibling; 13.8 years younger sibling) from the Sibling Interaction and Behavior Study (SIBS) to determine whether non-idiosyncratic environmental factors shared by siblings contributed to individual differences in a diverse set of behavioral outcomes. Evidence for shared environmental influence was sought for eight composite measures covering a wide array of adolescent functioning: Academic Achievement, Total IQ, Substance Use Disorders, Externalizing Disorders, Internalizing Disorders, Peer Groups, Disinhibited Personality, and Negative Emotionality. For six of eight composites, significant shared environmental effects, accounting for 14–22% of the variance, were observed for these same-sex sibling pairs. These findings support the use of adoptive sibling designs to directly estimate shared environmental effects and implicate the existence of systematic environmental influences on behavior that are potentially detectable. Edited by Dorret Boomsma and John Hewitt.  相似文献   
45.

Purpose

Alcohol use disorders, substance use disorders, and antisocial personality disorder share a common externalizing liability, which may also include attention-deficit hyperactivity disorder (ADHD). However, few studies have compared formal quantitative models of externalizing liability, with the aim of delineating the categorical and/or continuous nature of this liability in the community. This study compares categorical, continuous, and hybrid models of externalizing liability.

Method

Data were derived from the 2004–2005 National Epidemiologic Survey on Alcohol and Related Conditions (N = 34,653). Seven disorders were modeled: childhood ADHD and lifetime diagnoses of antisocial personality disorder (ASPD), nicotine dependence, alcohol dependence, marijuana dependence, cocaine dependence, and other substance dependence.

Results

The continuous latent trait model provided the best fit to the data. Measurement invariance analyses supported the fit of the model across genders, with females displaying a significantly lower probability of experiencing externalizing disorders. Cocaine dependence, marijuana dependence, other substance dependence, alcohol dependence, ASPD, nicotine dependence, and ADHD provided the greatest information, respectively, about the underlying externalizing continuum.

Conclusions

Liability to externalizing disorders is continuous and dimensional in severity. The findings have important implications for the organizational structure of externalizing psychopathology in psychiatric nomenclatures.  相似文献   
46.
47.
Predictors of trough serum gentamicin concentrations in neonates   总被引:1,自引:0,他引:1  
Neonates admitted to an intensive care nursery frequently receive gentamicin sulfate therapy. This study was undertaken to determine predictors of an elevated (greater than or equal to 2 mg/L) trough serum concentration of gentamicin sulfate (undesirable because of potential toxic effects). A total of 140 infants with birth weight of 496 to 4545 g and gestational age of 23 to 42 weeks who received gentamicin in the first days of life were studied prospectively. The trough serum concentration of gentamicin was not significantly affected by concurrent use of dopamine hydrochloride, indomethacin, furosemide, or umbilical artery catheters. Of 11 infants weighing between 1000 and 1500 g on an 18-hour dosing interval, 55% had trough serum gentamicin concentration of 2 mg/L or more. Use of the recommended 24-hour dosing interval for infants weighing less than 1000 g and an 18-hour schedule for preterm infants weighing more than 1000 g resulted in a significant number of elevated trough serum gentamicin concentrations in the latter. A dosing interval of 24 hours for infants less than 1500 g and 18 hours in infants between 1500 and 3250 g is suggested.  相似文献   
48.
A baby with unilateral cleft lip, midline cleft palate and hypertelorism developed meningitis in the first 48 h of life. Examination of the nasopharynx showed a soft tissue mass, which was confirmed as a basal encephalocele by computed tomography. There was also congenital hydrocephalus and the corpus callosum was absent. Surgical treatment included repair of the anterior basal skull defect, repair of the lip and palate, and ventriculo-peritoneal shunt. There is currently evidence of developmental delay and right-sided visual impairment due to Morning Glory syndrome. This case demonstrates that basal encephalocele should be considered in any baby with midline facial deformity who develops meningitis.  相似文献   
49.
BACKGROUND: This study was conducted to describe the rate and completeness of the recovery of testosterone production following prolonged temporary androgen ablative therapy in men with prostate carcinoma undergoing curative radiation therapy. METHODS: Two-hundred and sixty-seven men treated with between 3 months and 3 years of adjuvant androgen ablation (AA) were followed at 6-month intervals following cessation of their androgen deprivation therapy. A comparative group of 518 men not undergoing AA were also followed. RESULTS: Drugs used included low dose cyproterone/stilboestrol (CPA/DES) in combination (56%) and 1 month depot (18%) and 3 month depot (25%) leutinizing hormone releasing hormone agonist (LHRHa). Seventy-nine percent of men in the current study recovered normal testosterone levels (10nmol/L), and 93% recovered levels of at least 5nmol/L. In comparison, men who had never received androgen ablative therapy showed a fall of testosterone, with 17% having sub-normal levels after 3 years. Median time to testosterone recovery was 10 months. Factors associated on multivariate analysis with delayed testosterone recovery included advanced age (P = 0.008), low pre-therapy testosterone (P = 0.04), and the use of 3 month LHRHa preparations as compared with CPA/DES (P = 0.002) or 1 month LHRHa preparations (P = 0.015). The duration of drug use was not significantly associated with time to testosterone recovery. CONCLUSIONS: Long-acting LHRHa preparations appear to have a more prolonged action than previously supposed. Most men treated for up to 2 years recover normal testosterone levels after cessation of adjuvant androgen ablation, and the limited data available in the current study on patients treated for 3 years also suggests most will recover.  相似文献   
50.
Transgenic mice with both alleles of the p53 tumor suppressor gene product 'knocked out' by gene targeting are susceptible to early development of tumors, chiefly lymphomas and sarcomas. Compared with the control group, administration of dehydroepiandrosterone (DHEA) at 0.3% of the diet to male p53-deficient mice extended their lifespan by delaying death due to neoplasms (from 105 to 166 days on study, P = 0.002), primarily by suppressing lymphoblastic lymphoma (from 45 to 6% of neoplastic deaths, P = 0.010). Treatment with a synthetic DHEA analog, 16alpha-fluoro-5-androsten-17-one (compound 8354), at 0.15% of the diet also increased lifespan, to 140 days for mice that developed tumors (P = 0.037). The effects of these steroids on lifespan and tumor development did not appear to be strongly related to inhibition of food consumption and weight gain, in that a group pair-fed with control diet to the reduced food consumption of the DHEA-treated group developed and died of the same types of neoplasms at the same rate as the controls fed ad libitum. The chemopreventive effect of these steroids has been proposed to be due to suppression of DNA synthesis by inhibition of glucose 6-phosphate dehydrogenase, the rate-limiting enzyme of the pentose phosphate pathway. Although DHEA and its analog are strong non- competitive inhibitors of this enzyme in vitro, treatment with DHEA did not deplete cellular nucleotide pools in the liver, as would have been predicted. The chemopreventive effect of DHEA in this model may be due to steroid-induced thymic atrophy and suppression of T cell lymphoma, permitting these mice to survive long enough to develop tumors with longer latency.   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