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   23608篇
  免费   1753篇
  国内免费   153篇
耳鼻咽喉   207篇
儿科学   835篇
妇产科学   634篇
基础医学   3129篇
口腔科学   402篇
临床医学   2493篇
内科学   4860篇
皮肤病学   497篇
神经病学   2639篇
特种医学   594篇
外科学   2182篇
综合类   151篇
一般理论   37篇
预防医学   3082篇
眼科学   289篇
药学   1445篇
  1篇
中国医学   40篇
肿瘤学   1997篇
  2024年   33篇
  2023年   377篇
  2022年   685篇
  2021年   1203篇
  2020年   760篇
  2019年   998篇
  2018年   1069篇
  2017年   813篇
  2016年   874篇
  2015年   925篇
  2014年   1193篇
  2013年   1447篇
  2012年   2113篇
  2011年   2139篇
  2010年   1111篇
  2009年   941篇
  2008年   1380篇
  2007年   1315篇
  2006年   1213篇
  2005年   1052篇
  2004年   903篇
  2003年   766篇
  2002年   670篇
  2001年   116篇
  2000年   90篇
  1999年   104篇
  1998年   111篇
  1997年   98篇
  1996年   81篇
  1995年   92篇
  1994年   55篇
  1993年   59篇
  1992年   55篇
  1991年   53篇
  1990年   49篇
  1989年   48篇
  1988年   70篇
  1987年   42篇
  1986年   47篇
  1985年   33篇
  1984年   41篇
  1983年   25篇
  1982年   32篇
  1981年   37篇
  1980年   26篇
  1978年   15篇
  1977年   15篇
  1976年   16篇
  1974年   21篇
  1973年   13篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
22.
23.
Young children enter kindergarten with varying levels of readiness and abilities to learn. One factor that contributes to lower levels of school readiness is poverty. One timely, cost-effective, and feasible strategy to boost school readiness, regardless of exposure to high-quality preschool is to leverage the summer months prior to kindergarten entry and provide comprehensive, evidence-based programming immediately before the school year begins. The current study implemented a community-based summer programme targeted at improving school readiness for 25 four- and five-year-old children in a low-income community. Across the 9-week study, children participated in two types of early literacy activities and the Incredible Years social/emotional learning curriculum. Results indicate that participants demonstrated significant growth across three early literacy skills and were rated as overall stable regarding their behaviour across the summer. These results are discussed along with implications and future directions in this line of research.  相似文献   
24.
25.

Background

Radium 223 was introduced for metastatic castration-resistant prostate cancer based on the results of a randomized controlled trial showing risk reduction for death and skeletal events. Our aim was to evaluate the outcome of patients receiving radium 223 in a real-world setting.

Patients and Methods

We conducted a multicenter retrospective analysis in the Triveneto region of Italy.

Results

One hundred fifty-eight patients received radium 223 in our region. After a median follow-up of 9.5 months, 75 patients died. The median overall survival (OS) was 14.2 months, and the median progression-free survival (PFS) was 6.2 months. Seventy-one (45%) patients achieved progression as best response. Thirty-seven (23%) patients stopped the treatment early because of progression. Eastern Cooperative Oncology Group performance status was prognostic for OS (18.4 vs. 12.3 vs. 7.5 months; 0 vs. 1, P = .0062; 0 vs. 2, P = .0002), whereas previous prostatectomy or docetaxel exposure were not. A neutrophil to lymphocytes ratio ≥ 3 significantly impacted OS (18.1 vs. 9.7 months; P < .001) and slightly impacted PFS (6.6 vs. 5.6 months; P = .05). Patients with a baseline alkaline phosphatase (ALP) value ≥ 220 U/L had worse OS and PFS (24.1 vs. 10.5 months; 7.2 vs. 5.5 months; P < .001). Patients with changes in ALP value achieved better OS (P = .029) and PFS (P = .002). There was no difference according to the line of therapy (0 vs. ≥ 1; P = .490). The main grade 3/4 toxicities were anemia, asthenia, and thrombocytopenia.

Conclusion

This large real-world report confirms comparable OS and PFS data when compared with the pivotal study, as well as the predictive role of ALP and neutrophil to lymphocytes ratio. The definition of the optimal position of radium 223 in the treatment of metastatic castration-resistant prostate cancer has still to be defined.  相似文献   
26.
OBJECTIVE: The study aims to verify whether phonologic and rapid automatized naming (RAN) deficits are present and associated in Italian dyslexic children and whether they differentially affect dyslexics with and without a history of previous language delay (LD). BACKGROUND: According to the phonologic core deficit hypothesis, dyslexia may stem from impairment of the representation and manipulation of phonemes and may be closely associated with oral language deficits. However, deficits in tasks not requiring fine-grained phonologic representations, such as RAN, have also been described in dyslexic children. METHODS: Thirty-seven children were selected on the basis of a reading deficit and were assigned to 2 groups according to whether or not they had a history of early LD as determined retrospectively by parental report. A battery of reading and writing, verbal working memory, metaphonologic, RAN, and visual search tests were administered. RESULTS: RAN deficits were shared by most dyslexics (with and without a history of LD), whereas phonologic deficits were mainly associated with a previous LD. This last condition did not result in a more profound impairment of reading and writing decoding skills. CONCLUSION: In a shallow orthography such as Italian, RAN, not phonologic deficits, may represent the main cognitive marker of developmental dyslexia.  相似文献   
27.
28.
29.
30.
The efficiency of a new prothrombin-based activated protein C (APC) resistance test to detect factor V Leiden (FVL) was clinically evaluated in 150 Italian patients with deep venous thrombosis. Patient samples are diluted in factor-V-deficient plasma, an APC-containing reagent, and specific factor V activator; after incubation, clotting is initiated by addition of activated-factor-FV-dependent prothrombin activator. Two prothrombin time determinations were performed under identical assay conditions except that no APC was added to one. A ratio over 4.2 for normal individuals and under 2.0 for FVL patients is expected: between 1.3 and 1.9 for FVL heterozygotes, and between 1.0 and 1.1 for FVL homozygotes. Using a predefined cut-off ratio of 2.0, a specificity and a sensitivity of 1.00 for detection of FVL mutation were found. With a cut-off ratio of 1.1, a specificity of 0.98 and a sensitivity of 1.00 were found for discrimination between FVL heterozygous (n = 60) and homozygous (n = 6). No interferences by heparins, oral contraceptives, oral anticoagulant therapy, protein C, protein S, D-dimer, homocysteine, MTHFR mutations and antiphospholipid autoantibodies were detected. In our experience, this new prothrombin time-based APC resistance assay provides improved discrimination between normal individuals and FVL carriers compared with the classical methods. Moreover, this new assay allows good discrimination between homozygous and heterozygous FVL carriers. In the authors' experience this prothrombin time-based method was not influenced by many factors compared with the classical activated partial thromboplastin time-based method.  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