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   4943篇
  免费   474篇
  国内免费   45篇
耳鼻咽喉   24篇
儿科学   107篇
妇产科学   78篇
基础医学   644篇
口腔科学   95篇
临床医学   475篇
内科学   850篇
皮肤病学   52篇
神经病学   460篇
特种医学   150篇
外科学   633篇
综合类   94篇
一般理论   3篇
预防医学   651篇
眼科学   168篇
药学   433篇
中国医学   3篇
肿瘤学   542篇
  2021年   65篇
  2019年   54篇
  2018年   74篇
  2017年   48篇
  2016年   49篇
  2015年   64篇
  2014年   92篇
  2013年   143篇
  2012年   202篇
  2011年   225篇
  2010年   119篇
  2009年   107篇
  2008年   196篇
  2007年   214篇
  2006年   222篇
  2005年   229篇
  2004年   231篇
  2003年   169篇
  2002年   180篇
  2001年   165篇
  2000年   164篇
  1999年   173篇
  1998年   54篇
  1997年   72篇
  1996年   42篇
  1995年   47篇
  1994年   59篇
  1993年   60篇
  1992年   155篇
  1991年   122篇
  1990年   122篇
  1989年   106篇
  1988年   89篇
  1987年   81篇
  1986年   82篇
  1985年   104篇
  1984年   82篇
  1983年   69篇
  1982年   49篇
  1981年   60篇
  1980年   39篇
  1979年   66篇
  1978年   57篇
  1977年   40篇
  1975年   41篇
  1974年   42篇
  1973年   53篇
  1972年   51篇
  1971年   37篇
  1969年   43篇
排序方式: 共有5462条查询结果,搜索用时 15 毫秒
991.
Fatty acid 2-hydroxylase (FA2H) is responsible for the synthesis of myelin galactolipids containing hydroxy fatty acid (hFA) as the N-acyl chain. Mutations in the FA2H gene cause leukodystrophy, spastic paraplegia, and neurodegeneration with brain iron accumulation. Using the Cre-lox system, we developed two types of mouse mutants, Fa2h(-/-) mice (Fa2h deleted in all cells by germline deletion) and Fa2h(flox/flox) Cnp1-Cre mice (Fa2h deleted only in oligodendrocytes and Schwann cells). We found significant demyelination, profound axonal loss, and abnormally enlarged axons in the CNS of Fa2h(-/-) mice at 12 months of age, while structure and function of peripheral nerves were largely unaffected. Fa2h(-/-) mice also exhibited histological and functional disruption in the cerebellum at 12 months of age. In a time course study, significant deterioration of cerebellar function was first detected at 7 months of age. Further behavioral assessments in water T-maze and Morris water maze tasks revealed significant deficits in spatial learning and memory at 4 months of age. These data suggest that various regions of the CNS are functionally compromised in young adult Fa2h(-/-) mice. The cerebellar deficits in 12-month-old Fa2h(flox/flox) Cnp1-Cre mice were indistinguishable from Fa2h(-/-) mice, indicating that these phenotypes likely stem from the lack of myelin hFA-galactolipids. In contrast, Fa2h(flox/flox) Cnp1-Cre mice did not show reduced performance in water maze tasks, indicating that oligodendrocytes are not involved in the learning and memory deficits found in Fa2h(-/-) mice. These findings provide the first evidence that FA2H has an important function outside of oligodendrocytes in the CNS.  相似文献   
992.
993.
Physical therapists working in neurological practice must make choices about which standardized outcome measures are most appropriate for each patient. Significant time constraints in the clinic limit the number of measures that one can reasonably administer. Therapists must choose measures that will provide results that guide the selection of appropriate interventions and are likely to show clinically meaningful change. Therefore, therapists must be able to compare the merits of available measures to identify those that are most relevant for each patient and setting. This article describes a process for selecting outcome measures and illustrates the use of that process with a patient who has had a stroke. The link between selecting objective outcome measures and tracking patient progress is emphasized. Comparisons are made between 2 motor function measures (the Fugl-Meyer Assessment [FMA] of Physical Performance vs the Stroke Rehabilitation Assessment of Movement), and 2 balance measures (Berg Balance Scale vs the Activities-specific Balance Confidence Scale). The use of objective outcome measures allows therapists to quantify information that previously had been described in subjective terms. This allows the tracking of progress, and the comparison of effectiveness and costs across interventions, settings, providers, and patient characteristics.  相似文献   
994.
Deliberate attention to the management of soft tissue is imperative when performing an amputation. Identification and proper management of the nerves accompanied by the performance of a stable myodesis and ensuring robust soft-tissue coverage are measures that will improve patient outcomes. Limb length should be preserved when practicable; however, length preservation at the expense of creating a nonhealing or painful residual limb with poor soft-tissue coverage is contraindicated. While a large proportion of individuals with a trauma-related amputation remain severely disabled, a chronically painful residual limb is not inevitable and late revision amputations to improve soft-tissue coverage, stabilize the soft tissues (revision myodesis), or remove symptomatic neuromas can dramatically improve patient outcomes. Psychosocial issues may dramatically affect the outcomes after trauma-related amputations. A multidisciplinary team should be consulted or created to address the multiple complex physical, mental, and psychosocial issues facing patients with a recent amputation.  相似文献   
995.
The aim of this report was to describe the computed tomography features of injected carboxymethylcellulose and how it can be mistaken for tumor recurrence. Carboxymethylcellulose is a low-density injectable indicated for short-term vocal fold augmentation. When used in patients with head and neck cancer, differentiating this agent from a neoplastic recurrence can be difficult on imaging. The imaging findings of five patients who received carboxymethylcellulose augmentation are presented to illustrate a potential pitfall of image interpretation. When injectable carboxymethylcellulose is used in cancer patients, knowledge of the injection sites, material used, and procedural history can avoid misinterpretation of monitory imaging.  相似文献   
996.
Few studies have examined the association between non-steroidal anti-inflammatory drug (NSAID) use and risk of small cell lung cancer (SCLC); among them, findings are mixed. Recently, we found that use of NSAIDs was differentially associated with lung cancer risk by histology. Here, we examine, more comprehensively, the association between individual NSAIDs and SCLC risk. 75,546 residents of western Washington State, ages 50-76, completed a baseline questionnaire in 2000-2002 and reported on their use of individual NSAIDs over the past 10 years. NSAID use was categorized as non-users, low (<4 days/week or <4 years), and high (≥4 days/week and ≥4 years). 111 SCLC were identified through linkage to a population-based cancer registry. Multivariable-adjusted Cox proportional hazards models including strong adjustment for smoking were used to estimate hazard ratios (HR) and 95% confidence intervals (95% CI). Compared to non-use, high use of regular-strength aspirin was associated with an elevated risk of SCLC (HR 1.78, 95% CI: 1.05-3.02; P-trend=0.03). Findings for low-dose aspirin were elevated but did not reach statistical significance. Use of non-aspirin NSAIDs was not associated with SCLC risk. Our findings provide further indication of heterogeneity in the association between aspirin and lung cancer morphologies. Large, prospective studies with comprehensive assessments of NSAID use and smoking history and data on both men and women, are needed in order to better understand the association between use of aspirin and SCLC.  相似文献   
997.
We report an infant with normal neurological development and phenotype who developed bilateral retinoblastoma (RB). This patient, despite lack of dysmorphic features, demonstrated constitutional abnormality of the long arm of chromosome 13 on standard karyotype. We recommend systematic cytogenetic examinations complemented by fluorescent in situ hybridization as second-line screening in all patients suspected for hereditary RB despite negative RB1 molecular screening and normal phenotype.  相似文献   
998.
999.
1000.
The use of colonoscopy in colorectal cancer (CRC) screening has increased substantially in recent years. Media messages and changes in insurance reimbursement, as well as new screening guidelines from the American Cancer Society and the US Preventive Services Task Force, have contributed to this increase. Primary care providers (PCPs) are frequently responsible for making the recommendation and referral for screening. The process of successfully referring a patient for screening colonoscopy can be cumbersome and requires a coordinated effort between the PCP and the endoscopist. In recognition of the potential complexity of this process, the National Colorectal Cancer Roundtable has issued a report to describe the components of a quality screening colonoscopy referral system in primary care practice. The elements of a quality program include an optimal scheduling and referral system, the appropriate patient preparation information, consistent reporting and follow–up systems, and a detailed approach to dealing with special situations. CA Cancer J Clin 2010. © 2009 American Cancer Society, Inc.  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