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   36229篇
  免费   2262篇
  国内免费   110篇
耳鼻咽喉   322篇
儿科学   1167篇
妇产科学   1011篇
基础医学   4951篇
口腔科学   616篇
临床医学   5935篇
内科学   6598篇
皮肤病学   598篇
神经病学   3452篇
特种医学   607篇
外科学   3143篇
综合类   403篇
一般理论   55篇
预防医学   4532篇
眼科学   468篇
药学   2119篇
中国医学   68篇
肿瘤学   2556篇
  2023年   197篇
  2022年   382篇
  2021年   776篇
  2020年   459篇
  2019年   779篇
  2018年   896篇
  2017年   619篇
  2016年   647篇
  2015年   834篇
  2014年   1173篇
  2013年   1783篇
  2012年   2654篇
  2011年   2805篇
  2010年   1530篇
  2009年   1288篇
  2008年   2543篇
  2007年   2551篇
  2006年   2570篇
  2005年   2388篇
  2004年   2307篇
  2003年   2188篇
  2002年   2046篇
  2001年   222篇
  2000年   156篇
  1999年   300篇
  1998年   413篇
  1997年   368篇
  1996年   327篇
  1995年   280篇
  1994年   271篇
  1993年   253篇
  1992年   167篇
  1991年   138篇
  1990年   136篇
  1989年   131篇
  1988年   110篇
  1987年   116篇
  1986年   94篇
  1985年   110篇
  1984年   157篇
  1983年   157篇
  1982年   194篇
  1981年   167篇
  1980年   159篇
  1979年   93篇
  1978年   74篇
  1977年   81篇
  1976年   60篇
  1975年   53篇
  1974年   68篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
992.
993.

Introduction and hypothesis

The goal of this study was to characterize associations between caffeine consumption and severity of urinary incontinence (UI) in US women. We hypothesized that moderate and high caffeine intake would be associated with UI in US women when controlling for other factors associated with UI.

Methods

US women participated in the 2005–2006 and 2007–2008 National Health and Nutrition Examination Survey (NHANES), a cross-sectional, nationally representative survey. Using the Incontinence Severity Index, UI was categorized as “any” and “moderate/severe”. Types of UI included stress, urge, mixed, and other. Food diaries were completed, and average water (grams/day), total dietary moisture (grams/day), and caffeine (milligrams/day) intake were calculated into quartiles. Stepwise logistic regression models were constructed adjusting for sociodemographics, chronic diseases, body mass index, self-rated health, depression, physical activity, alcohol use, dietary water and moisture intake, and reproductive factors.

Results

From the 4,309 nonpregnant women (aged ≥20 years) who had complete UI and dietary data, UI prevalence for any UI was 41.0 % and 16.5 % for moderate/severe UI, with stress UI the most common type (36.6 %). Women consumed a mean caffeine intake of 126.7 mg/day. After adjusting for multiple factors, caffeine intake in the highest quartile (≥204 mg/day) was associated with any UI [prevalence odds ratio (POR) 1.47, 95 % confidence interval (CI) 1.07–2.01], but not moderate/severe UI (POR 1.42, 95 % CI 0.98–2.07). Type of UI (stress, urgency, mixed) was not associated with caffeine intake.

Conclusions

Caffeine intake ≥204 mg/day was associated with any UI but not with moderate/severe UI in US women.  相似文献   
994.
Study ObjectiveTo present a new research problem-based learning discussion (PBLD) conference and to evaluate its effect on residents.DesignRetrospective observational study of resident education before and after implementation of a research PBLD.SettingLarge U.S. academic anesthesiology department.Subjects93 anesthesiology residents with research PBLD exposure in the academic year (AY) 2010 and AY 2011, and 85 residents without research PBLD exposure in AY 2008 and AY 2009.MeasurementsSince AY 2010, a PBLD format has been used to teach residents clinical research fundamentals. The annual 90-minute PBLD addressed residents’ perceived barriers to research and introduced research resources available via the Clinical and Translational Science Institute (CTSI). Data recorded were: 1) number of residents who made CTSI consultation solicitations as a new investigator, and 2) number of new research projects proposed by the residents and designed with CTSI consultation. Each outcome was compared between the prePBLD group (AY 2008 [n=43] and AY 2009 [n=42]) and the postPBLD group (AY 2010 [n=43] and AY 2011 [n=50]).Main ResultsThe number of residents who consulted the CTSI as new investigators increased from 4 of 85 residents (4.7%) in the prePBLD group to 13 of 93 residents (14.0%) in the postPBLD group (P = 0.042). The number of new research projects for which the residents consulted CTSI increased from 10 to 20 (100% increase).ConclusionA PBLD format for research education of anesthesiology residents is effective.  相似文献   
995.
PurposeThis randomized, open-label phase II study compared the efficacy of sunitinib monotherapy with that of single-agent standard-of-care (SOC) chemotherapy in patients with previously treated advanced triple-negative breast cancer (TNBC).MethodsPatients with advanced TNBC, relapsed after anthracycline- and taxane-based chemotherapy, were randomized to receive either sunitinib (37.5 mg/day) or the investigator's choice of SOC therapy. Progression-free survival was the primary endpoint.ResultsMedian progression-free survival was 2.0 months with sunitinib and 2.7 months with SOC chemotherapy (one-sided P = 0.888). Median overall survival was not prolonged with sunitinib (9.4 months) compared with SOC chemotherapy (10.5 months; one-sided P = 0.839). The objective response rate was 3% with sunitinib and 7% with SOC chemotherapy (one-sided P = 0.962).ConclusionsSunitinib monotherapy did not improve efficacy compared with SOC chemotherapy in patients with previously treated advanced TNBC, for which identification of effective treatments and therapeutic targets remains an urgent need.Trial registrationNCT00246571.  相似文献   
996.
997.
This study aimed to investigate immediate cell survival and distribution following different administration routes of mesenchymal stem cells (MSCs) into naturally occurring tendon injuries. Ten million MSCs, labeled with technetium‐99m hexamethylpropyleneamine oxime, were implanted into 13 horses with naturally occurring tendon or ligament injuries intra‐lesionally, intravenously and by regional perfusion, and traced for up to 48 h using planar gamma scintigraphy. Labeling efficiencies varied between 1.8% and 18.5% (mean 9.3%). Cells were retained in the damaged area after intra‐lesional administration but only 24% of cells were still present within the tendon after 24 h. After intravenous injection, cells largely distributed to the lung fields, with no detectable cells in the tendon lesions. Significant labeling of the tendon lesions was observed in 11/12 horses following regional perfusion but at a lower level to intra‐lesional injection. The highest cell numbers were retained after intra‐lesional injection, although with considerable cell loss, while regional perfusion may be a viable alternative for MSC delivery. Cells did not “home” to damaged tendon in large numbers after intravenous administration. Cells were detected in the lungs most frequently after intravascular administration, although with no adverse effects. Low cell retention has important implications for designing effective clinical therapies for human clinical use. © 2013 Orthopaedic Research Society Published by Wiley Periodicals, Inc. J Orthop Res 31:1096–1102, 2013  相似文献   
998.
Establishing whether men and women tend to express different symptoms of posttraumatic stress in reaction to trauma is important for both etiological research and the design of assessment instruments. Use of item response theory (IRT) can reveal how symptom reporting varies by gender and help determine if estimates of symptom severity for men and women are equally reliable. We analyzed responses to the PTSD Checklist (PCL) from 2,341 U.S. military veterans (51% female) who completed deployments in support of operations in Afghanistan and Iraq (Operation Enduring Freedom/Operation Iraqi Freedom [OEF/OIF]), and tested for differential item functioning by gender with an IRT‐based approach. Among men and women with the same overall posttraumatic stress severity, women tended to report more frequent concentration difficulties and distress from reminders whereas men tended to report more frequent nightmares, emotional numbing, and hypervigilance. These item‐level gender differences were small (on average d = 0.05), however, and had little impact on PCL measurement precision or expected total scores. For practical purposes, men's and women's severity estimates had similar reliability. This provides evidence that men and women veterans demonstrate largely similar profiles of posttraumatic stress symptoms following exposure to military‐related stressors, and some theoretical perspectives suggest this may hold in other traumatized populations.  相似文献   
999.
Psychological distress and coping strategies following intimate partner violence (IPV) victimization may impact survivors’ risk for future IPV. The current study prospectively examined the impact of distinct posttraumatic stress disorder (PTSD) symptom clusters (reexperiencing, avoidance, numbing, and hyperarousal), dissociation, and coping strategies (engagement and disengagement coping) on IPV revictimization among recently abused women. Women (N = 69) who were seeking services for IPV and experienced their most recent episode of physical IPV between 2 weeks and 6 months prior to study enrollment completed measures of physical IPV, psychological distress, and coping strategies at baseline and at 6‐month follow‐up. The women averaged 36 years of age and 67% of the sample was African American. Separate Poisson regression analyses revealed that PTSD hyperarousal symptoms, dissociation, engagement coping, and disengagement coping each significantly predicted physical IPV revictimization at the 6‐month follow‐up (with effect sizes ranging from a 1.20–1.34 increase in the likelihood of Time 2 physical IPV with a 1 SD increase in the predictor). When these significant predictors were examined together in a single Poisson regression model, only engagement and disengagement coping were found to predict physical IPV revictimization such that disengagement coping was associated with higher revictimization risk (1.29 increase in the likelihood of Time 2 physical IPV with one SD increase in disengagement coping) and engagement coping was associated with lower revictimization risk (1.30 decrease in the likelihood of Time 2 physical IPV with one SD increase in engagement coping). The current findings suggest that coping strategies are important and potentially malleable predictors of physical IPV revictimization.  相似文献   
1000.

Background

Mutations in inverted formin, FH2, and WH2 domain containing (INF2) are common causes of dominant focal segmental glomerulosclerosis. INF2 encodes a member of the diaphanous-related formin family, which regulates actin and microtubule cytoskeletons. Charcot-Marie-Tooth neuropathy (CMT) is a group of inherited disorders affecting peripheral neurons. Many reports have shown that glomerulopathy can associate with CMT. However, it has been unclear whether these two processes in the same individual represent one disorder or if they are two separate diseases.

Case diagnosis/treatment

Recently, INF2 mutations were identified in 12 of 16 patients with CMT-associated glomerulopathy, suggesting that these mutations are a common cause of the dual phenotype. In this study, we report two cases of CMT-associated glomerulopathy that both showed INF2 mutations. A novel INF2 mutation, p. L77P, was identified in a family in which the dual phenotype was inherited in a dominant fashion. The pathogenic effect of p. L77P was proposed using a structural homology model. In addition, we identified a patient with a sporadic CMT-associated glomerulopathy carrying a known INF2 mutation: p. L128P.

Conclusions

Our study confirms the link between INF2 mutations and CMT-associated glomerulopathy and widens the spectrum of pathogenic mutations.  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