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   3591篇
  免费   466篇
  国内免费   10篇
耳鼻咽喉   32篇
儿科学   158篇
妇产科学   325篇
基础医学   278篇
口腔科学   82篇
临床医学   1159篇
内科学   427篇
皮肤病学   119篇
神经病学   174篇
特种医学   302篇
外科学   292篇
综合类   86篇
一般理论   5篇
预防医学   269篇
眼科学   59篇
药学   182篇
肿瘤学   118篇
  2023年   50篇
  2021年   35篇
  2020年   47篇
  2019年   53篇
  2018年   84篇
  2017年   114篇
  2016年   108篇
  2015年   128篇
  2014年   145篇
  2013年   146篇
  2012年   93篇
  2011年   141篇
  2010年   147篇
  2009年   145篇
  2008年   120篇
  2007年   126篇
  2006年   108篇
  2005年   113篇
  2004年   102篇
  2003年   97篇
  2002年   69篇
  2001年   90篇
  2000年   74篇
  1999年   81篇
  1998年   110篇
  1997年   123篇
  1996年   123篇
  1995年   108篇
  1994年   71篇
  1993年   62篇
  1992年   48篇
  1991年   51篇
  1990年   47篇
  1989年   69篇
  1988年   71篇
  1987年   54篇
  1986年   62篇
  1985年   63篇
  1984年   46篇
  1983年   38篇
  1982年   36篇
  1981年   32篇
  1979年   30篇
  1978年   30篇
  1977年   29篇
  1976年   24篇
  1975年   33篇
  1971年   25篇
  1970年   20篇
  1968年   20篇
排序方式: 共有4067条查询结果,搜索用时 15 毫秒
61.
This study examined racial/ethnic and socioeconomic differences in service utilization across sectors (specialty mental health, school, primary care) for youth at risk for depression. Our sample included 362 adolescents who were enrolled in a larger project examining the effects of an indicated school-based depression prevention program. Service use across sectors mirrored national trends and previous research findings in which the education sector was most frequently utilized for mental health services. Race/ethnicity was significantly associated with parent-reported specialty mental health service utilization, even when controlling for other predictors of use. The study also suggests that racial disparities in service access generally appear to be reduced through the availability of education sector mental health services. Socioeconomic status was not associated with service use in any sector when controlling for other predictors. Parent–child agreement was moderate for report of specialty mental health service use and low for report of use of services within the education and primary care sectors.  相似文献   
62.
63.
The molecular circuitries controlling the process of skin wound healing have gained new significant insights in recent years. This knowledge is built on landmark studies on skin embryogenesis, maturation, and differentiation. Furthermore, the identification, characterization, and elucidation of the biological roles of adult skin epithelial stem cells and their influence in tissue homeostasis have provided the foundation for the overall understanding of the process of skin wound healing and tissue repair. Among numerous signaling pathways associated with epithelial functions, the PI3K/Akt/mTOR signaling route has gained substantial attention with the generation of animal models capable of dissecting individual components of the pathway, thereby providing a novel insight into the molecular framework underlying skin homeostasis and tissue regeneration. In this review, we focus on recent findings regarding the mechanisms involved in wound healing associated with the upregulation of the activity of the PI3K/Akt/mTOR circuitry. This review highlights critical findings on the molecular mechanisms controlling the activation of mTOR, a downstream component of the PI3K–PTEN pathway, which is directly involved in epithelial migration and proliferation. We discuss how this emerging information can be exploited for the development of novel pharmacological intervention strategies to accelerate the healing of critical size wounds.  相似文献   
64.
65.
ABSTRACT

Objectives: Glioblastoma is the most common primary malignant brain tumor in adults, and despite decades of intensive research regarding its pathophysiology and treatment, the prognosis for glioblastoma patients remains poor. While many studies have analyzed various factors that may influence survival outcomes, the focus of this brief review is to discuss the influence that apatient’s race/ethnicity has on survival. This factor has been investigated in large population-based studies and in smaller institutional analyses, but the prognostic utility of this factor has been inconsistent. Discussion of this topic is therefore warranted to better equip providers to counsel and treat patients with glioblastoma, as well as to identify areas of future research.

Methods: A comprehensive literature search is performed to identify studies that reported GBM survival outcomes by race/ethnicity.

Results: Although some discrepancies exist, asignificant survival benefit is associated with the Asian or Pacific Islander (API) race, whereas white patients have the poorest survival and highest incidence. Hispanic patients tend to fare better than white patients but have worse survival than APIs.

Discussion: Further analysis into the differences in survival among different races may lead to an increased understanding of potential molecular and genetic targets, thus guiding future treatment plans for these patients.

Abbreviations: AAAIR: Average Annual Age-Adjusted Incidence Rate; AI/AN: American Indian or Alaska Native; API: Asian or Pacific Islander; CBTRUS: Central Brain Tumor Registry of the United States; CUMC: Columbia University Medical Center; EOR: Extent of Resection; Exc: Excluded; GBM: Glioblastoma; GTR: Gross Total Resection; IDH-1: Isocitrate Dehydrogenase 1; MGMT: O6-Methylguanine DNA Methyltransferase; NCDB: National Cancer Database; OS: Overall Survival; O/U: Other/Unknown; PFS: Progression-Free Survival; SEER: Surveillance, Epidemiology, and End Results; S&W BTR: Scott & White Brain Tumor Registry; UCLA: University of California Los Angeles; UM: University of Miami.  相似文献   
66.
Abstract

Communication partners is a novel aphasia treatment plan whose aim is to restore a sense of purpose, direction, and control to daily life for both patient and caregiver. Treatment involves the participation of a community volunteer who, once paired with an aphasic adult, acts as a liaison in bridging clinical and real-life pursuits. Initially, treatment pairs are taught how to interact freely and effectively. Once comfortable in each other's company these partners embark on activities of the patient's choosing at home or in the community. Results from 10 treated pairs failed to yield significant differences on the Boston Diagnostic Aphasia Exmamination, Communication Abilities in Daily Living, or the Affect Balance Scale. However, all participants, i.e. patients, caregivers, and communication partners, noted statistically significant gains in the aphasic adult's well-being and communication on two investigator-constructed questionnaires. Other informal measures also supported the use of this treatment. The significance of these findings, as well as methodological considerations when undertaking this type of research, are discussed.  相似文献   
67.
68.
The Editor-in-Chief has retracted the published paper "ProtectiveEffects of  相似文献   
69.
Identification of the signalling cascades that are differentially activated during prostatic tumourigenesis is a crucial step in the search for future molecular targets in this disease. The stress-activated protein kinase (SAPK) signalling cascade culminates in the phosphorylation of the JNK and p38 mitogen-activated protein kinases (MAPKs). Recently, the upstream activators of these proteins, the MAPK kinases (MKKs), have been implicated as inhibitors of tumour progression in a variety of clinical and experimental tumour models. This study evaluates MKK4, MKK6 and MKK7 expression during prostate cancer progression in humans and in the transgenic adenocarcinoma of a mouse prostate (TRAMP) model of prostate tumourigenesis. Benign prostate, prostatic intraepithelial neoplasia (PIN) lesions and tumour tissues were collected from 37 TRAMP mice. Additionally, six tissue microarrays were constructed with tumours from a matched group of 102 men who underwent radical prostatectomy. Tissues from 20 patients with extensive high-grade prostatic intraepithelial neoplasia (HGPIN) were also analysed. For all samples, immunohistochemical staining for MKK4, MKK6 and MKK7 was scored in normal and neoplastic glands. Staining intensities of MKK4, MKK6 and MKK7 were significantly increased in HGPIN and prostate cancer compared to surrounding normal glands in both the TRAMP and human samples (p < 0.0001 for all markers). Increased levels of MKK4 or MKK7 correlated with higher pathological stage at prostatectomy (p = 0.01 and p = 0.04). Using multivariate analysis, there was no association between protein levels and time to biochemical recurrence in the human samples. The up-regulation of MKK4, MKK6 and MKK7 during prostate cancer progression in both TRAMP and human tissues highlights an important role for the SAPK signalling cascade in prostatic neoplasia. The finding that higher MKK4 and MKK7 expression is associated with higher-stage prostatic tumours underscores the dynamic regulation of these proteins during prostatic tumourigenesis.  相似文献   
70.
Gas-to-liquid (GTL) products are synthetic hydrocarbons produced from natural gas using a catalytic process known as the Fischer–Tropsch process. This process yields a synthetic crude oil that consists of saturated hydrocarbons which can subsequently be refined to a range of products analogous to those obtained from petroleum refining. However, in contrast to their petroleum-derived analogs, GTL products are essentially free of unsaturated or aromatic compounds and do not contain any sulfur-, oxygen-, or nitrogen-containing compounds. Under new chemical substance notification requirements, an extensive testing program covering the entire portfolio of GTL products has been undertaken to assess their hazardous properties to human health and environment. The results of these studies have been summarized in a two-part review. Part 1 provides an overview of the mammalian toxicity hazardous properties of the various GTL products. This second part of the review focuses on the aquatic, sediment, terrestrial, and avian toxicity studies which assess the ecotoxicological hazard profile of the GTL products. Many challenges were encountered during these tests relating to dosing, analysis and interpretation of results. These are discussed with the intent to share experiences to help inform and shape future regulatory mandates for testing of poorly soluble complex substances. As was the case with the mammalian toxicology review, there were a few cases where adverse effects were found, but overall the GTL products were found to exert minimal adverse ecotoxicological effects and these were less severe than effects observed with their conventional, petroleum-derived analogs.  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