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   3587篇
  免费   264篇
  国内免费   6篇
耳鼻咽喉   61篇
儿科学   171篇
妇产科学   66篇
基础医学   409篇
口腔科学   105篇
临床医学   352篇
内科学   556篇
皮肤病学   62篇
神经病学   558篇
特种医学   303篇
外科学   538篇
综合类   55篇
一般理论   2篇
预防医学   219篇
眼科学   39篇
药学   176篇
  1篇
中国医学   10篇
肿瘤学   174篇
  2021年   60篇
  2020年   37篇
  2019年   55篇
  2018年   55篇
  2017年   59篇
  2016年   58篇
  2015年   68篇
  2014年   97篇
  2013年   101篇
  2012年   144篇
  2011年   155篇
  2010年   114篇
  2009年   98篇
  2008年   131篇
  2007年   129篇
  2006年   153篇
  2005年   130篇
  2004年   124篇
  2003年   113篇
  2002年   98篇
  2001年   109篇
  2000年   108篇
  1999年   85篇
  1998年   71篇
  1997年   64篇
  1996年   68篇
  1995年   75篇
  1994年   66篇
  1993年   62篇
  1992年   71篇
  1991年   59篇
  1990年   70篇
  1989年   83篇
  1988年   73篇
  1987年   90篇
  1986年   70篇
  1985年   64篇
  1984年   55篇
  1983年   42篇
  1982年   37篇
  1981年   34篇
  1980年   31篇
  1979年   36篇
  1978年   39篇
  1977年   31篇
  1976年   27篇
  1975年   28篇
  1973年   16篇
  1970年   16篇
  1968年   16篇
排序方式: 共有3857条查询结果,搜索用时 31 毫秒
951.

Purpose

The aim of the study was to evaluate the surgical outcome of esophageal atresia (EA) without fistula for 24 years at a single tertiary center for pediatric surgery.

Methods

The study used a retrospective chart review of infants diagnosed with EA without fistula between 1981 and 2005.

Results

Of 33 patients with EA without fistula, 31 charts were available. Mean birth weight was 2327 g (range, 905-3390 g), and 71% were male. Most common associated anomalies were cardiac (n = 6; 19%) and renal (n = 5; 16%), followed by vertebral (n = 4; 13%) and anorectal (n = 2; 7%). The median initial esophageal gap was 5 vertebral bodies. Six had a primary repair, and 25 patients had esophageal replacement at a median age of 7 months. This involved gastric transposition in 20 (1 followed failed jejunal interposition), colonic interposition in 5, jejunal interposition in 1 (after a failed colonic), and repair at another center in 1. With a median review of 9 years, 21 patients had long-term sequelae with the need for multiple further surgical procedures including an antireflux procedure in 5. One patient died.

Conclusions

Management of EA without fistula remains challenging. Most patients required staged treatment that included esophageal replacement. The frequency of late complications indicates the need for programmed long-term review.  相似文献   
952.
953.
BACKGROUND: Controversy exists regarding occurrence and measurement of structural variants of albumin in urine. In this study, we examined cross-reactivity of in vitro modified albumins in assays for urine albumin (microalbumin). METHODS: We analyzed albumin modified by reagents, trypsin, or physical treatments or differing in primary sequence (animal albumins) with an immunoturbidimetric assay (Beckman LX20) using goat antiserum and a competitive immunoassay (Siemens Immulite) using a monoclonal antibody. We assessed occurrence of albumin fragments in urine by use of Western blotting of 24 specimens. RESULTS: Chemical modification, modest sequence substitution (gorilla albumin), or cleavage of albumin by cyanogen bromide (CNBr) had little effect on reactivity in the LX20 assay. Albumin extensively cleaved with trypsin retained partial reactivity. The Immulite assay generally was affected more severely by albumin modifications and sequence changes. Western blots of fresh urine specimens or specimens stored at -80 degrees C showed little albumin fragmentation, but some specimens stored for 3 years at -20 degrees C had extensively fragmented albumin that was detected by the LX20 but not the Immulite assay. CONCLUSIONS: Nearly equivalent reactivity of intact albumin and CNBr fragments in the immunoturbidimetric assay indicates reactivity of antibodies with multiple epitopes throughout albumin. Therefore, it is difficult to abolish reactivity of albumin in this type of urine albumin assay. Differential sensitivity of 2 assays to albumin modification identifies a potential source of assay nonequivalence in measuring urinary albumin, particularly for specimens stored at -20 degrees C.  相似文献   
954.
BACKGROUND: The Individual Placement and Support (IPS) model of supported employment for clients with severe mental illness has been described as a standardization of evidence-based supported employment. Although several reviews on the literature on its effectiveness have been conducted, the completion of several new studies suggests an updated review is warranted. METHODS: We conducted a comprehensive literature search for randomized controlled trials of IPS, limiting our review to programs with high-fidelity IPS programs, locating 11 studies. We examined the following competitive employment outcomes: employment rates, days to first job, annualized weeks worked, and job tenure in longest job held during the follow-up period. FINDINGS: Across the 11 studies, the competitive employment rate was 61% for IPS compared to 23% for controls. About two-thirds of those who obtained competitive employment worked 20 hours or more per week. Among those who obtained a competitive job, IPS participants obtained their first job nearly 10 weeks earlier than did controls. Among IPS participants who obtained competitive work, duration of employment after the start of the first job averaged 24.2 weeks per year, or 47% of the 52-week year. CONCLUSIONS: The current review is consistent with earlier reviews, although the evidence for high-fidelity IPS appears to be somewhat stronger here than in reviews evaluating studies with more heterogeneity in the supported employment models examined. The number, consistency, and effect sizes of studies of evidence-based supported employment establish it as one of the most robust interventions available for persons with severe mental illness.  相似文献   
955.
BACKGROUND: There is increasing interest in whether methamphetamine is an emerging recreational drug in the UK. AIM: To determine what evidence is there that methamphetamine use is an emerging drug in the UK compared to established recreational drugs such as MDMA. Design and methods: We undertook a retrospective study collating data on the number of enquiries to both our poisons centre and the UK National Poisons Information Service (NPIS) relating to all recreational drugs, methamphetamine and MDMA; presentations to our Emergency Department (ED) with acute methamphetamine toxicity and the frequency of positive urine tests for methamphetamine and MDMA in workplace drug screening programmes. RESULTS: There was a small increase in the number of methamphetamine-related calls to our poisons centre, but it remained uncommon (0.1% of all recreational drugs cases in 2000 to 1.23% in 2006) compared to MDMA (17.3-42.7% of all recreational drugs cases). The number of 2005/6 enquiries to the UK NPIS for methamphetamine was 12, compared to 455 MDMA enquiries (0.014 and 0.52% of all enquiries, respectively). There were five presentations to our ED relating to methamphetamine over a 15-month period compared to 171 for MDMA. Of the 254 440 urine samples screened for the presence of drugs in the workplace (2000-06), three were positive for methamphetamine and 147 for MDMA. CONCLUSION: There is no evidence of increasing use of methamphetamine or that acute methamphetamine poisoning is a significant clinical problem compared to established recreational drugs such as MDMA. In our opinion, healthcare, educational and law enforcement resources should be proportionally directed towards tackling drugs that pose an immediate and continuing healthcare risk to the population rather than emerging recreational drugs.  相似文献   
956.

Purpose

We report our experience of the management of arterial occlusion in the newborn.

Methods

A case note review was carried out after ethical approval. Doppler ultrasonography confirmed the occlusion. Thrombolysis was the primary intervention. Surgery was used selectively. A good outcome was one without tissue loss or functional impairment or minimal tissue loss without functional impairment. Data are presented as medians with ranges.

Results

Ten patients (9 male; median gestational age, 35.5 weeks [range, 28-39 weeks]) presented on day 1 (range, 1-8 days). Initial management included systemic tissue plasminogen activator (8 patients) and surgery (2 infants in whom thrombolysis was contraindicated). Improvement was noted in 7 of 8 infants treated medically and in both who underwent surgery. Three infants had significant tissue loss. Outcome at 29 months (range, 1.3-95.4 months) was good in the remaining 7.

Conclusions

A multidisciplinary approach, thrombolysis and selective surgery achieved tissue preservation and function in the majority while minimizing complications. Early referral to centers with multidisciplinary teams is recommended.  相似文献   
957.
Aldosterone:renin ratio (ARR) is used to screen for hyperaldosteronism. Data regarding correlates of ambulatory ARR in the community and its relation to hypertension incidence are limited. We defined clinical correlates of ARR, determined its heritability, tested for association and linkage, and related ARR to blood pressure (BP) progression in nonhypertensive individuals among 3326 individuals from the Framingham Heart Study (53% women; mean age: 59 years). Ambulatory morning ARR (serum aldosterone and plasma renin concentrations) were related to clinical covariates, genetic variation across the REN locus, a 10-cM linkage map, and among nonhypertensive participants (n=1773) to progression of >or=1 Sixth Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure BP category (optimal: <120/80 mm Hg, normal: 120 to 129/80 to 84 mm Hg, high normal: 130 to 139/85 to 89 mm Hg, hypertension: >or=140/90 mm Hg), or incident hypertension (systolic BP: >or=140 mm Hg, diastolic BP: >or=90 mm Hg, or use of antihypertensive treatment). ARR was positively associated with age, female sex, untreated hypertension, total/high-density lipoprotein cholesterol ratio, hormone replacement therapy, and beta-blocker use, but negatively associated with angiotensin-converting enzyme inhibitor and diuretic use. ARR was heritable (h(2)=0.40), had modest linkage to chromosome 11p (logarithm of the odds: 1.89), but was not associated with 17 common variants in REN (n=1729). On follow-up (mean: 3 years), 607 nonhypertensive individuals (34.2%) developed BP progression, and 283 (16.0%) developed hypertension. Higher baseline logARR was associated with increased risk of BP progression (odds ratio per SD increment: 1.23; 95% CI: 1.11 to 1.37) and hypertension incidence (odds ratio per SD increment: 1.16; 95% CI: 1.00 to 1.33). ARR is a heritable trait influenced by clinical and genetic factors. There is a continuous gradient of increasing risk of BP progression across ARR levels in nonhypertensive individuals.  相似文献   
958.
Gelastic seizures are relatively uncommon and rarely observed secondary to frontal lobe lesions. This report presents magnetoencephalography (MEG) and diffusion tensor imaging (DTI) findings in an adolescent with gelastic seizures secondary to a left anterior cingulate gyrus lesion. Ictal scalp video EEG showed bilateral frontal 4 Hz theta discharges. Interictal EEG showed left fronto-temporal spikes or sharp waves. Interictal MEG showed spike sources over bilateral temporal regions. DTI and tractography delineated slightly shifted corpus callosum posterior to the lesion, unaffected uncinate and inferior longitudinal fasciculi. The patient became seizure free for 12 months after surgical excision of a pleomorphic xanthoastrocytoma in the left anterior cingulate region. In our patient, MEG and EEG did not localize the deep-seated epileptogenic zone. The combination of DTI and neurophysiologic studies, however, possibly disclosed neuronal connections within the epileptic network and indicated that epileptic discharges propagated via the uncinate fibers from the primary epileptogenic zone in the anterior cingulate region to the mesial temporal region in this case with gelastic seizures secondary to a cingulate lesion.  相似文献   
959.
960.
OBJECTIVE: Individuals with diabetes and individuals with serious mental illness are more likely than the general population to die prematurely. The study examined the impact of diabetes on mortality among 197 individuals with co-occurring psychotic and substance use disorders who participated in a randomized controlled study of integrated mental health and substance abuse treatment. METHODS: The authors examined Medicaid claims for evidence of diabetes and applied survival analyses to examine whether time from study entry until death was different for individuals with and without evidence of diabetes. RESULTS: Of individuals with co-occurring psychotic and substance use disorders, 21% had evidence of diabetes. In a 12-year period, 41% of those with evidence of diabetes died compared with 10% of those without evidence of diabetes. CONCLUSIONS: Interventions targeted for diabetes prevention and diabetes management are critical for persons with serious mental illness, particularly among those who also abuse substances.  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