全文获取类型
收费全文 | 6707篇 |
免费 | 561篇 |
国内免费 | 14篇 |
专业分类
耳鼻咽喉 | 68篇 |
儿科学 | 205篇 |
妇产科学 | 113篇 |
基础医学 | 841篇 |
口腔科学 | 99篇 |
临床医学 | 903篇 |
内科学 | 1289篇 |
皮肤病学 | 105篇 |
神经病学 | 634篇 |
特种医学 | 186篇 |
外科学 | 1075篇 |
综合类 | 55篇 |
一般理论 | 3篇 |
预防医学 | 550篇 |
眼科学 | 105篇 |
药学 | 527篇 |
中国医学 | 8篇 |
肿瘤学 | 516篇 |
出版年
2023年 | 60篇 |
2022年 | 94篇 |
2021年 | 327篇 |
2020年 | 198篇 |
2019年 | 256篇 |
2018年 | 296篇 |
2017年 | 213篇 |
2016年 | 179篇 |
2015年 | 262篇 |
2014年 | 278篇 |
2013年 | 389篇 |
2012年 | 514篇 |
2011年 | 543篇 |
2010年 | 257篇 |
2009年 | 190篇 |
2008年 | 321篇 |
2007年 | 314篇 |
2006年 | 328篇 |
2005年 | 252篇 |
2004年 | 236篇 |
2003年 | 219篇 |
2002年 | 179篇 |
2001年 | 112篇 |
2000年 | 92篇 |
1999年 | 86篇 |
1998年 | 47篇 |
1997年 | 44篇 |
1996年 | 47篇 |
1995年 | 40篇 |
1994年 | 25篇 |
1993年 | 28篇 |
1992年 | 78篇 |
1991年 | 69篇 |
1990年 | 63篇 |
1989年 | 62篇 |
1988年 | 45篇 |
1987年 | 61篇 |
1986年 | 46篇 |
1985年 | 55篇 |
1984年 | 59篇 |
1983年 | 23篇 |
1979年 | 22篇 |
1978年 | 18篇 |
1977年 | 18篇 |
1974年 | 20篇 |
1973年 | 23篇 |
1971年 | 17篇 |
1970年 | 16篇 |
1968年 | 18篇 |
1966年 | 15篇 |
排序方式: 共有7282条查询结果,搜索用时 328 毫秒
91.
Kyle Telander Sybil G. Hosek Diana Lemos Gihane Jeremie-Brink 《Global public health》2017,12(11):1391-1403
Social context plays a significant role in adolescent identity development, particularly for youth lacking traditional systems of support. Using ecological and symbolic interactionism perspectives, this study qualitatively explored the psychosocial identity development of Black gay, bisexual, or transgendered youth participating in the House Ball Community (HBC). The HBC is a diverse network of family-like structures called ‘houses’, as well as a glamorous social outlet via pageant-like ‘balls’ in which participants compete. A series of focus groups were conducted with youth and leaders from the HBC (n?=?37; age range?=?17–24). Via cross-case and comparative analyses, specific motivating factors related to entry into and continued involvement in the community were identified. Factors related to entry into the community included lack of safe spaces, opportunities for acceptance, means of subsistence, and allure of the scene. Factors related to continued involvement included resilience and coping skills development, sexual identity acceptance and pride, prevalence of risky behaviour, and risk of exploitation. Discussion of these factors provides insight on how self-constructed, supplementary social contexts may provide both unique supports and risks to members, allowing for more focused and well-informed interventions and policies to enhance healthy development in such communities while mitigating risk. 相似文献
92.
Abigail B. Shoben Kyle D. Rudser Scott S. Emerson 《Journal of biopharmaceutical statistics》2017,27(1):135-147
Statistical intuition suggests that increasing the total number of observations available for analysis should increase the precision with which parameters can be estimated. Such monotonic growth of statistical information is of particular importance when data are analyzed sequentially, such as in confirmatory clinical trials. However, monotonic information growth is not always guaranteed, even when using a valid, but inefficient estimator. In this article, we demonstrate the theoretical possibility of nonmonotonic information growth when using generalized estimating equations (GEE) to estimate a slope and provide intuition for why this possibility exists. We use theoretical and simulation-based results to characterize situations that may result in nonmonotonic information growth. Nonmonotonic information growth is most likely to occur when (1) accrual is fast relative to follow-up on each individual, (2) correlation among measurements from the same individual is high, and (3) measurements are becoming more variable further from randomization. In situations that may lead to nonmonotonic information growth, study designers should plan interim analyses to avoid situations most likely to result in nonmonotonic information growth. 相似文献
93.
94.
Three theories currently compete to explain the conceptual deficits that result from brain damage: sensory-functional theory, domain-specific theory, and conceptual structure theory. We argue that all three theories capture important aspects of conceptual deficits, and offer different insights into their origins. Conceptual topography theory (CTT) integrates these insights, beginning with A. R. Damasio's (1989) convergence zone theory and elaborating it with the similarity-in-topography (SIT) principle. According to CTT, feature maps in sensory-motor systems represent the features of a category's exemplars. A hierarchical system of convergence zones then conjoins these features to form both property and category representations. According to the SIT principle, the proximity of two conjunctive neurons in a convergence zone increases with the similarity of the features they conjoin. As a result, conjunctive neurons become topographically organised into local regions that represent properties and categories. Depending on the level and location of a lesion in this system, a wide variety of deficits is possible. Consistent with the literature, these deficits range from the loss of a single category to the loss of multiple categories that share sensory-motor properties. 相似文献
95.
Diagnosis of invasive pulmonary aspergillosis (IPA) is a challenging process in immunocompromised patients. Galactomannan (GM) antigen detection in bronchoalveolar lavage (BAL) fluid is a method to detect IPA with improved sensitivity over conventional studies. We sought to determine the diagnostic yield of BAL GM assay in a diverse population of immunocompromised patients. A retrospective review of 150 fiberoptic bronchoscopy (FOB) with BAL for newly diagnosed pulmonary infiltrate in immunocompromised patients was performed. Patient information, procedural details and laboratory studies were collected. BAL and serum samples were evaluated for GM using enzyme‐linked immunoassay. Of 150 separate FOB with BAL, BAL GM was obtained in 143 samples. There were 31 positive BAL GM assays. In those 31 positive tests, 13 were confirmed as IPA, giving a positive predictive value of 41.9%. There was one false negative BAL GM. Of the 18 false positive BAL GM, 4 were receiving piperacillin–tazobactam and 11 were receiving an alternative beta‐lactam antibiotic. BAL GM assay shows excellent sensitivity for diagnosing IPA. There was a significant number of false positive BAL GM assays and several of those patients were receiving beta‐lactam antibiotics at the time of bronchoscopy. 相似文献
96.
97.
98.
99.
100.
Aaron S. Farberg Mary A. Hall Leah Douglas Kyle R. Covington Sarah J. Kurley Robert W. Cook 《Current medical research and opinion》2020,36(8):1301-1307
AbstractObjective: To integrate gene expression profiling into the management of high-risk cutaneous squamous cell carcinoma (cSCC) within the National Comprehensive Cancer Network (NCCN) guidelines to improve risk-aligned management recommendations.Methods: A cohort of 300 NCCN-defined high-risk cSCC patients, along with the American Joint Committee on Cancer (AJCC) T stage, Brigham and Women’s Hospital (BWH) T stage, and known patient outcomes were analyzed. Risk classifications using a validated 40-gene expression profile (40-GEP) test and T stage were applied to NCCN patient management guidelines. Risk-directed patient management recommendations within the NCCN guidelines framework were aligned based on risk for metastasis.Results: Of the 300 NCCN high-risk cSCC patients, 159 (53.0%) were 40-GEP Class 1 and AJCC T1-T2, and 173 (57.7%) were Class 1 and BWH T1-2a, indicating low risk for metastasis and, thereby, suggesting low management intensity. The 40-GEP integration suggested high intensity management for only 24 (8.0%) patients (all Class 2B), and moderate intensity management for the remainder of the cohort.Conclusions: The 40-GEP test can be integrated within existing NCCN guideline recommendations for managing cSCC patients to help refine risk-directed management decisions. Integration of the 40-GEP test would allow >50% of this NCCN-defined high-risk cohort to be managed with the lowest intensity recommendations within the broad NCCN guidelines. High intensity management was deemed risk-appropriate for a small subpopulation (8.0%). This study demonstrates that the 40-GEP test, in combination with T stage, has clinical utility to impact patient management decisions in NCCN high-risk cSCC for improving risk-aligned management within the NCCN guidelines framework. 相似文献