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   931篇
  免费   36篇
  国内免费   4篇
耳鼻咽喉   4篇
儿科学   23篇
妇产科学   24篇
基础医学   142篇
口腔科学   4篇
临床医学   94篇
内科学   172篇
皮肤病学   32篇
神经病学   60篇
特种医学   71篇
外科学   93篇
综合类   5篇
预防医学   98篇
眼科学   2篇
药学   60篇
中国医学   3篇
肿瘤学   84篇
  2023年   2篇
  2022年   13篇
  2021年   23篇
  2020年   6篇
  2019年   12篇
  2018年   22篇
  2017年   6篇
  2016年   8篇
  2015年   7篇
  2014年   15篇
  2013年   34篇
  2012年   57篇
  2011年   66篇
  2010年   35篇
  2009年   31篇
  2008年   73篇
  2007年   86篇
  2006年   88篇
  2005年   69篇
  2004年   72篇
  2003年   68篇
  2002年   49篇
  2001年   8篇
  2000年   4篇
  1999年   14篇
  1998年   10篇
  1997年   8篇
  1996年   13篇
  1995年   4篇
  1994年   11篇
  1993年   10篇
  1992年   6篇
  1991年   2篇
  1990年   5篇
  1989年   4篇
  1988年   5篇
  1987年   5篇
  1986年   4篇
  1985年   3篇
  1984年   2篇
  1981年   3篇
  1980年   1篇
  1979年   1篇
  1978年   1篇
  1977年   1篇
  1975年   1篇
  1965年   1篇
  1960年   1篇
  1958年   1篇
排序方式: 共有971条查询结果,搜索用时 0 毫秒
71.
We conducted a mortality time series study to investigate the association between daily mortality for congestive heart failure (CHF), and daily concentrations of particles and gaseous pollutants in the ambient air of Montreal, Quebec, during the period 1984-1993. In addition, using data from the universal Quebec Health Insurance Plan, we identified individuals >/=65 years of age who, one year before death, had a diagnosis of CHF. Fixed-site air pollution monitors in Montreal provided daily mean levels of pollutants. We regressed the logarithm of daily counts of mortality on the daily mean levels of each pollutant, after accounting for seasonal and subseasonal fluctuations in the mortality time series, non-Poisson dispersion, weather variables, and other gaseous and particle pollutants. Using cause of death information, we did not find any associations between daily mortality for CHF and any air pollutants. The analyses of CHF defined from the medical record showed positive associations with coefficient of haze, the extinction coefficient, SO(2), and NO(2). For example, the mean percent increase in daily mortality for an increase in the coefficient of haze across the interquartile range was 4.32% (95% CI: 0.95-7.80%) and for NO(2) it was 4.08% (95% CI: 0.59-7.68%). These effects were generally higher in the warm season.  相似文献   
72.

Publications Received

Geriatric nephrology and urology literature  相似文献   
73.
PROMOTIONOFINVITROGROWTHOFHUMANMEDULLOBLASTOMACELLSBYEXOGENEOUSIL-6LiuJiai刘佳;LiHong李宏;HamouMarie-France;NicolasdeTribolet(1Di...  相似文献   
74.

Background  

How youth perceive marketing messages in sports is poorly understood. We evaluated whether youth perceive that the imagery of a specific sports marketing advertisement contained smoking-related messages.  相似文献   
75.
Treatment options are limited in infections caused by extended-spectrum beta-lactamase (ESBL)-producing Enterobacteriaceae, with carbapenems generally preferred. Disturbingly, however, carbapenem-resistant strains are emerging worldwide. Here we report two clinical isolates, one Escherichia coli and one Klebsiella pneumoniae, each with high-level carbapenem resistance (imipenem minimum inhibitory concentration of 32 microg/mL). They were isolated following imipenem therapy from two hospital patients who had received imipenem therapy in different regions of Turkey. Both isolates produced OXA-48-like carbapenemases, enzymes so far reported only from Turkey. Both isolates also had group 1 CTX-M-type ESBLs and had lost major outer membrane proteins. OXA-48-like carbapenemases appear to be scattered in Turkey and surveillance to determine their prevalence is warranted.  相似文献   
76.
为进一步认识白血病抑制因子(LIF)对人髓母细胞瘤生长的生物学作用,我们使用LIF反义寡核苷酸,在髓母细胞内特异性阻断LIF基因表达并观察它对靶细胞的生物学效应。结果发现,被处理细胞的LIF表达降低至RT/PCR检出的阈值之下,抗LIF的免疫组织化学染色亦呈阴性,同时,这些细胞的生长速度明显减缓。相反,用与反义寡核苷酸互补的正义序列处理的细胞无论在基因表达/产生,还是在生长速度方面,均和正常培养细胞的细胞相似,本研究从而提示了一条以LIF为对象的髓母细胞瘤以及其它LIF生长依赖性肿瘤的基因和免疫治疗途径。  相似文献   
77.
Heterogeneity of NSD1 alterations in 116 patients with Sotos syndrome   总被引:1,自引:0,他引:1  
Sotos syndrome is an overgrowth syndrome characterized by distinctive facial features, learning difficulties, and macrocephaly with frequent pre- and postnatal overgrowth with advanced bone age. Here, we report on our experience in the molecular diagnostic of Sotos syndrome on 116 patients. Using direct sequencing and a quantitative multiplex PCR of short fluorescent fragments (QMPSF)-based assay allowing accurate detection of both total and partial NSD1 deletions, we identified NSD1 abnormalities in 104 patients corresponding to 102 Sotos families (90%). NSD1 point mutations were detected in 80% of the index cases, large deletions removing the NSD1 gene entirely in 14%, and intragenic NSD1 rearrangements in 6%. Among the 69 detected distinct point mutations, 48 were novel. The QMPSF assay detected an exonic duplication and a mosaic partial deletion. QMPSF mapping of the 15 large deletions revealed the heterogeneity of the deletions, which vary in size from 1 to 4.5 Mb. Clinical features of NSD1-positive Sotos patients revealed that the phenotype in patients with nontruncating mutations was less severe that in patients with truncating mutations. This study confirms the heterogeneity of NSD1 alterations in Sotos syndrome and therefore the need to complete sequencing analysis by screening for partial deletions and duplications to ensure an accurate molecular diagnosis of this syndrome.  相似文献   
78.
BACKGROUND AND OBJECTIVES: The purpose of this study was to assess the performances of a single-component adhesive system when an Er:YAG laser was used to prepare cavities. STUDY DESIGN/MATERIALS AND METHODS: Shear bond strength tests were performed on composite rods bonded with a single-component adhesive system to dentin surfaces prepared using either bur+acid, Er:YAG laser (fluence = 44 J/cm2), or Er:YAG laser+acid. Class V cavities were prepared differently according to the molar surface: buccal surfaces were prepared using a diamond bur, and lingual surfaces using the Er:YAG laser. In group 1, cavity walls were not acid treated after Er:YAG laser preparation. In group 2, only the enamel walls were acid treated. In group 3, all the enamel and dentin walls were acid treated. Microleakage was assessed using a methylene blue dye penetration method. RESULTS: Bond strength values did not differ significantly between the three groups (P = 0.162). Better marginal adaptation was obtained between the composite resin and cavity walls when Er:YAG laser preparation was followed by a total acid etching (P = 0.008). CONCLUSIONS: Our results supported the use of single-component adhesive systems in cavities prepared using Er:YAG laser. The step of acid etching must be maintained for the whole cavity walls in regard of the microleakage values.  相似文献   
79.
OBJECTIVE: To investigate the clinical safety and efficacy of two dosages of tolterodine in older patients with symptoms attributable to overactive bladder. DESIGN: Randomized, double-blind, placebo-controlled, parallel-group, multinational, phase III study. SETTING: Incontinence, older care, urological, and urogynecological clinics in the United Kingdom, France, and the Republic of Ireland. PARTICIPANTS: One hundred and seventy-seven older patients (age > or =65 years) with symptoms of urinary urgency, increased frequency of micturition (> or =8 micturitions/24 hours), and/or urge incontinence (> or =1 episode/24 hours). INTERVENTION: Tolterodine 1 mg or 2 mg twice daily (bid), or placebo, for 4 weeks. MEASUREMENTS: Safety and tolerability were evaluated through spontaneously reported adverse events, electrocardiogram, and blood pressure measurements. Efficacy was assessed using micturition diary variables: mean change from baseline in frequency of micturition and number of incontinence episodes/24 hours. RESULTS: The mean age of the patient population was 75 years. Overall, > or =87% of patients completed the study. Neither dosage of tolterodine was associated with serious drug-related adverse events during the study. No cardiac arrythmogenic events were noted. Dry mouth (mild to moderate intensity) was the most common adverse event in both the placebo and tolterodine treatment groups. Three percent of patients in the tolterodine 2 mg bid group discontinued treatment because of dry mouth, compared with 2% of placebo-treated patients. Compared with placebo, statistically significant decreases in micturition frequency were apparent in both tolterodine treatment groups. Furthermore, patients treated with tolterodine 2 mg bid had statistically significant decreases in urge incontinence episodes/24 hours and increases in volume voided per micturition compared with placebo. CONCLUSION: Tolterodine (taken for 4 weeks) is safe and shows efficacy, particularly at a dosage of 2 mg bid, in the treatment of older patients with urinary symptoms attributable to overactive bladder.  相似文献   
80.
Despite the heterogeneous clinical presentations, the majority of patients with 22q11.2 deletion syndrome (22q11.2 DS) have either a common recurrent 3 Mb deletion or a less common, 1.5 Mb nested deletion, with breakpoint sites in flanking low-copy repeats (LCR) sequences. Only a small number of atypical deletions have been reported and precisely defined. Haploinsufficiency of the TBX1 gene was determined to be the likely cause of 22q11.2 DS. The diagnostic procedure usually used is FISH using commercially probes (N25 or TUPLE1). However, this test does not contain TBX1, and fails to detect deletions that are either proximal or distal to the FISH probes. Here, we report on two patients with clinical features suggestive of 22q11.2 DS, a male infant with facial dysmorphia, pulmonary atresia, ventricular septal defect, neonatal hypocalcemia, and his affected mother, with facial dysmorphia, learning disabilities, and hypernasal speech. They were tested negative for 22q11.2 DS using N25 or TUPLE1 probes, but were shown deleted for a probe containing TBX1. Delineation of the deletion was performed using high-density SNP arrays (Illumina, 370K). This atypical deletion was spanning 1.89 Mb. The distal breakpoint resided in LCR-D, sharing the same distal breakpoint with the 3 Mb common deletion. The proximal breakpoint was located 105 kb telomeric to TUPLE1, representing a new breakpoint variant that does not correspond to known LCRs of 22q11.2. We conclude that FISH with the TBX1 probe is an accurate diagnostic tool for 22q11.2 DS, with a higher sensitivity than FISH using standard probes, detecting all but the rarest deletions, greatly reducing the false negative rate.  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