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   685篇
  免费   59篇
  国内免费   1篇
耳鼻咽喉   1篇
儿科学   33篇
妇产科学   48篇
基础医学   75篇
口腔科学   32篇
临床医学   56篇
内科学   100篇
皮肤病学   26篇
神经病学   65篇
特种医学   7篇
外科学   70篇
综合类   11篇
一般理论   1篇
预防医学   101篇
眼科学   5篇
药学   61篇
肿瘤学   53篇
  2022年   4篇
  2021年   12篇
  2020年   9篇
  2019年   8篇
  2018年   14篇
  2017年   8篇
  2016年   11篇
  2015年   8篇
  2014年   12篇
  2013年   27篇
  2012年   42篇
  2011年   36篇
  2010年   15篇
  2009年   18篇
  2008年   34篇
  2007年   43篇
  2006年   22篇
  2005年   32篇
  2004年   39篇
  2003年   25篇
  2002年   18篇
  2001年   20篇
  2000年   12篇
  1999年   19篇
  1998年   9篇
  1997年   7篇
  1996年   6篇
  1995年   7篇
  1994年   7篇
  1993年   4篇
  1992年   16篇
  1991年   17篇
  1990年   8篇
  1989年   16篇
  1988年   23篇
  1987年   10篇
  1986年   13篇
  1985年   7篇
  1984年   17篇
  1983年   15篇
  1982年   6篇
  1978年   4篇
  1977年   8篇
  1974年   4篇
  1973年   4篇
  1972年   9篇
  1971年   5篇
  1970年   5篇
  1967年   3篇
  1966年   6篇
排序方式: 共有745条查询结果,搜索用时 15 毫秒
51.
ObjectiveResearch has focused on understanding risk factors associated with suicidal ideation and self-harm behaviors in older youth, but less is known regarding these behaviors in preadolescents. We examined characteristics associated with suicidal ideation and self-harm behavior in youth aged 10–13 years.Design/MethodsA community sample of 387 youth was enrolled in a prospective study assessing precursors of risk behaviors. Twenty-three subjects endorsing items regarding suicidal ideation or self-harm behaviors (Achenbach's Youth Self-Report) (endorsers) were matched with 23 non-endorsers. Groups were compared on problem behaviors, impulsivity, neurocognitive function, risk behaviors, and other variables.ResultsEndorsers had higher levels of impulsivity, were more likely in borderline/clinical range on 5 of 8 Youth Self-Report Syndrome scales, and reported more risk taking. Endorsers and non-endorsers were similar in neurocognitive function. More non-endorsers were on stimulants, but groups were similar in parental monitoring and parental report of behavioral/emotional issues, socioeconomic status, and marital status.ConclusionIn this study, preadolescent endorsers report significantly more problem behaviors than non-endorsers. However, parental monitoring and parent report of problems were similar between groups. Given these findings, we suggest that at-risk youth may be underrecognized at young ages.  相似文献   
52.
The aim of this investigation was to develop and evaluate the feasibility and acceptability of a parental support intervention. A new measure of perceived parental support for stopping smoking was also developed. The sample included 59 adolescent-parent pairs recruited from a mid-sized Midwestern town during 2000-2003. The mean +/- SD age of the participants (32 males, 27 females) was 16.3 +/- 0.9 (range 14-18) years and 86% were Caucasian, 7% American Indian, 5% African American, and 2% Hispanic. Participants were randomized to parental support or minimum behavioral intervention. Severity of nicotine dependence was evaluated using the Fagerstr?m Tolerance Questionnaire, and perceived social support was evaluated using the Family Environment Scale and the new measure of perceived parent support for stopping smoking that was developed as part of this investigation. Treatment attendance, adherence, and acceptability were also evaluated. The parental support intervention was feasible but not superior to the minimum behavioral intervention with respect to attendance, retention, or change in support. This study expands on the knowledge of treating adolescent smokers and presents a new assessment measure. The study's limitations are noted. This investigation was funded by NICHHD.  相似文献   
53.
Background: Catheter‐related bloodstream infection (CRBSI) is a common complication in patients receiving home parenteral nutrition (HPN). Data regarding catheter salvage after a CRBSI episode are limited. We aimed to determine the incidence of CRBSI and rates of catheter salvage in adult patients receiving HPN. Materials and Methods: We retrospectively searched our prospectively maintained HPN database for the records of all adult patients receiving HPN from January 1, 1990, to December 31, 2013, at our tertiary referral center. Data abstracted from the medical records included demographics, diseases, treatments, and outcomes. The incidence of CRBSI and rates of catheter salvage were determined. Results: Of 1040 patients identified, 620 (59.6%) were men. The median total duration on HPN was 124.5 days (interquartile range, 49.0–345.5 days). Mean (SD) age at HPN initiation was 53.3 (15.3) years. During the study period, 465 CRBSIs developed in 187 patients (18%). The rate of CRBSI was 0.64/1000 catheter days. Overall, 70% of catheters were salvaged (retained despite CRBSI) during the study period: 78% of infections with coagulase‐negative staphylococci, 87% with methicillin‐sensitive Staphylococcus aureus, and 27% with methicillin‐resistant S aureus. The percentage of catheters salvaged was 63% from 1990 to 1994, 63% from 1995 to 1999, 61% from 2000 to 2004, 72% from 2005 to 2009, and 76% from 2010 to 2013. Conclusion: Catheter salvage is possible after a CRBSI episode. Since most episodes of CRBSI are caused by skin commensals, effective treatment without removal of the central venous catheter is possible in most cases.  相似文献   
54.
Introduction:Catheter‐related bloodstream infection (CRBSI) is a serious complication in patients receiving home parenteral nutrition (HPN). Antibiotic lock therapy (ALT) and ethanol lock therapy (ELT) can be used to prevent CRBSI episodes in high‐risk patients. Methods: Following institutional review board approval, all patients enrolled in the Mayo Clinic HPN program from January 1, 2006, to December 31, 2013, with catheter locking were eligible to be included. Patients without research authorization and <18 years old at the initiation of HPN were excluded. Total number of infections before and after ALT or ELT were estimated in all patients. Results: A total of 63 patients were enrolled during the study period. Of 59 eligible patients, 29 (49%) were female, and 30 (51%) were male. The median duration of HPN was 3.66 (interquartile range, 0.75–8.19) years. The mean age ± SD at initiation of HPN was 49.89 ± 14.07 years. A total of 51 patients were instilled with ALT, and 8 patients were instilled with ELT during their course of HPN. A total of 313 CRBSI episodes occurred in these patients, 264 before locking and 49 after locking (P < .001). Rate of infection per 1000 catheter days was 10.97 ± 25.92 before locking and 1.09 ± 2.53 after locking (P < .001). Discussion: The major findings of the present study reveal that ALT or ELT can reduce the overall rate of infections per 1000 catheter days. ALT or ELT can be used in appropriate clinical setting for patients receiving HPN.  相似文献   
55.
Background: Although home parenteral nutrition (HPN) is lifesaving for patients with chronic intestinal failure (IF), long-term use can be associated with complications such as infections, metabolic abnormalities, and IF–associated liver disease (IFALD). The key to treatment of many of these complications is prevention. Guidelines recommend avoidance of overfeeding, use of oral/enteral nutrition if possible, cyclic PN, and maintaining dose of soybean oil (SO) intravenous lipid emulsion (ILE) <1 g/kg/day as preventive strategies for IFALD. Additionally, with development of IFALD, ω-6/ω-3 polyunsaturated fatty acid ratio should be decreased in ILE. The newly available mixed-oil (MO) ILE offers such an opportunity; however, there is a paucity of long-term data available. Methods: The current study reports our long-term experience with MO ILE use in HPN patients. Results: Seventeen patients (8 female and 9 male) with an average age of 47 ± 12 years and median HPN duration of 4.6 years (1.1–32.1 years) have utilized MO ILE for >12 months after being transitioned from SO ILE because of intolerance. Use of MO ILE allowed an increase in ILE energy from 8% ± 8% to 22% ± 8% while reducing dextrose energy from 66% ± 8% to 54% ± 5%, maintaining stability in alkaline phosphatase and triglyceride levels, and achieving improvement in aspartate aminotransferase, alanine aminotransferase, total bilirubin, and α-tocopherol levels. Conclusion: In this HPN cohort with SO ILE intolerance, MO ILE was well tolerated and allowed an improvement in macronutrient composition while improving some liver parameters over a 12-month period.  相似文献   
56.
A contemporary influenza type B virus was passaged in vitro in the presence of increasing concentrations of the neuraminidase inhibitors, zanamivir and oseltamivir carboxylate (0.1-1000 microM over nine passages). After the fifth passage in the presence of zanamivir (10 microM), the virus acquired a Glu 119 Asp neuraminidase mutation (influenza A N2 subtype numbering) in the enzyme active site. After a further three passages, in which growth occurred in 100 microM of zanamivir, a Gln 218 Lys mutation (A (H3) numbering) in the HA1 domain of the haemagglutinin was found. In a fluorescence-based neuraminidase inhibition assay, viruses with the Glu 119 Asp NA mutation had a 32,000-fold reduction in sensitivity to the NA inhibitor zanamivir compared to the wild-type virus, while the mutation resulted in a 105-fold reduction in sensitivity to oseltamivir carboxylate. Viruses grown in the presence of 1000 microM oseltamivir carboxylate did not acquire any neuraminidase mutations but did have a His 103 Gln substitution (A (H3) numbering) in the HA1 region of the haemagglutinin which was demonstrated to significantly reduce receptor binding strength in vitro. Tissue culture assays demonstrated that the HA mutation caused a seven-fold reduction in sensitivity to oseltamivir carboxylate, and a 90-fold reduction in sensitivity to zanamivir.  相似文献   
57.
Background: Misconnections between enteral supplies and other access devices have led to significant morbidity and mortality. To reduce misconnections, a standard small‐bore connector has been developed (International Organization for Standards 80369‐8; ENFit). The full impact of transition to this connector is not known, however. Method: Working with major manufacturers and Food and Drug Administration, we obtained ENFit and comparative legacy tubes of variable sizes (low‐profile, 14F, 18F, 20F, and 24F balloon gastrostomies). Gravity enteral feeding was simulated with an empty bolus syringe attached to the feeding tube to be tested. The tube was clamped and filled to the 60‐mL mark with liquid (water, Jevity 1 Cal, Isosource HN, Isosource 1.5 Cal, Two Cal HN, and Nourish). The clamp was released, and time for formula to leave the syringe was recorded. Results: There was no difference in flow rate between the aggregate legacy and ENFit tubes for the low‐profile, 18F, and 20F sizes. The ENFit 14F tubes had a lower flow rate vs the legacy tubes, largely due to the low flow rates seen with the 1 ENFit tube. Similarly, 24F ENFit tubes with some formulas yielded lower flow rates as opposed to legacy. Conclusion: Overall, for the low‐profile, 18F, and 20F sizes, the ENFit tubes had similar flow rates when compared with the legacy tubes. For the 14F and 24F sizes, the flow rate of ENFit tubes was significantly lower, which could result in longer EN delivery for patients who are using these tubes to provide gravity feeding.  相似文献   
58.
Analysis of mutations I117V and I117M in the neuraminidase of influenza A pandemic (H1N1) 2009 viruses showed that I117V confers a mild reduction in oseltamivir sensitivity and has a synergistic effect of further increasing resistance when combined with H275Y. Contrary to recent reports, the I117M mutation does not alter oseltamivir sensitivity.  相似文献   
59.
BACKGROUND: Primary care treatment of depression needs improvement. OBJECTIVE: To evaluate the efficacy of 2 augmentations to antidepressant drug treatment. DESIGN: Randomized trial comparing usual care, telehealth care, and telehealth care plus peer support; assessments were conducted at baseline, 6 weeks, and 6 months. SETTING: Two managed care adult primary care clinics. PARTICIPANTS: A total of 302 patients starting antidepressant drug therapy. INTERVENTIONS: For telehealth care: emotional support and focused behavioral interventions in ten 6-minute calls during 4 months by primary care nurses; and for peer support: telephone and in-person supportive contacts by trained health plan members recovered from depression. MAIN OUTCOME MEASURES: For depression: the Hamilton Depression Rating Scale and the Beck Depression Inventory; and for mental and physical functioning: the SF-12 Mental and Physical Composite Scales and treatment satisfaction. RESULTS: Nurse-based telehealth patients with or without peer support more often experienced 50% improvement on the Hamilton Depression Rating Scale at 6 weeks (50% vs 37%; P =.01) and 6 months (57% vs 38%; P =.003) and on the Beck Depression Inventory at 6 months (48% vs 37%; P =. 05) and greater quantitative reduction in symptom scores on the Hamilton scale at 6 months (10.38 vs 8.12; P =.006). Telehealth care improved mental functioning at 6 weeks (47.07 vs 42.64; P =.004) and treatment satisfaction at 6 weeks (4.41 vs 4.17; P =.004) and 6 months (4.20 vs 3.94; P =.001). Adding peer support to telehealth care did not improve the primary outcomes. CONCLUSION: Nurse telehealth care improves clinical outcomes of antidepressant drug treatment and patient satisfaction and fits well within busy primary care settings.  相似文献   
60.
Human milk oligosaccharides are known to play a role in protection against certain infectious diseases. Previous reports indicate that the content of human milk oligosaccharides varies widely among individuals at term but such information on preterm milk is lacking. After removal of the fat, protein and most of the lactose from non-pooled human milk samples, a total neutral oligosaccharide fraction was isolated by ion-exchange chromatography followed by gel filtration. A Dionex high-performance anion-exchange chromatography system equipped with a pulsed electrometric detector was then employed to measure the levels of ten neutral oligosaccharides in the individual milk samples. Twenty-three milk samples from thirteen mothers who delivered at a mean gestational age of 29.5 (SD 3.1) weeks were collected between days 0 and 33 of lactation, and compared with three samples of term milk from two mothers. The ranges of the total and individual levels of the ten neutral oligosaccharides in preterm milk were similar to those in term milk. Further, as previously described in term milk, preterm milk exhibited a quantitative individual variation. This variation was independent of the gestational age, day of lactation, and postconceptional age. In conclusion, levels of ten neutral oligosaccharides did not differ between preterm and term human milk.  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