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   45872篇
  免费   2977篇
  国内免费   257篇
耳鼻咽喉   390篇
儿科学   1309篇
妇产科学   1226篇
基础医学   6062篇
口腔科学   983篇
临床医学   4612篇
内科学   10011篇
皮肤病学   986篇
神经病学   4856篇
特种医学   1518篇
外科学   6055篇
综合类   199篇
一般理论   19篇
预防医学   3461篇
眼科学   784篇
药学   2860篇
  1篇
中国医学   87篇
肿瘤学   3687篇
  2024年   53篇
  2023年   477篇
  2022年   754篇
  2021年   1820篇
  2020年   1067篇
  2019年   1501篇
  2018年   1725篇
  2017年   1211篇
  2016年   1351篇
  2015年   1567篇
  2014年   2145篇
  2013年   2676篇
  2012年   3969篇
  2011年   3954篇
  2010年   1996篇
  2009年   1878篇
  2008年   3170篇
  2007年   3061篇
  2006年   2769篇
  2005年   2727篇
  2004年   2283篇
  2003年   2040篇
  2002年   1806篇
  2001年   276篇
  2000年   201篇
  1999年   265篇
  1998年   316篇
  1997年   234篇
  1996年   210篇
  1995年   192篇
  1994年   163篇
  1993年   126篇
  1992年   111篇
  1991年   109篇
  1990年   98篇
  1989年   75篇
  1988年   60篇
  1987年   56篇
  1986年   48篇
  1985年   49篇
  1984年   51篇
  1983年   30篇
  1982年   47篇
  1981年   36篇
  1980年   45篇
  1979年   29篇
  1978年   23篇
  1977年   23篇
  1975年   25篇
  1974年   24篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
991.
Proteoglycans (PGs) as a whole, or when considering their GAG chains as single entities, are emerging as key regulators of tumor progression. Expectations on using them as putative prognostic markers and potential therapeutic targets are increasing coincidentally. Due to the multitude of biological roles that they may invest and the ample spectrum of cellular processes that they may control, we still need to learn better how they regulate phenomena such as intracellular signaling, proliferation, apoptosis, motility, and drug resistance. Depending on the type, their expression pattern, and the accessibility of their molecular ligands, PGs can either promote or inhibit tumorigenesis. The structural and functional diversity of PGs coupled with their ubiquitous abundance place them at the crossroads of many critical steps within the metastatic cascade. As this phenomenon is the pivotal factor for patient survivals, particular attention should be given to the understanding of how PGs govern metastasis formation.  相似文献   
992.
Journal of Autism and Developmental Disorders - This study describes charges, outcomes, and recidivism in both the juvenile and adult criminal justice systems (CJS) for young adults aged 17 to...  相似文献   
993.
Objectives: The aim of this study was to assess thyroid function as well as the prevalence and clinical value of anti-thyroid antibodies in patients with rheumatoid arthritis (RA).

Methods: Seventy patients with active RA (ACR criteria), 9 males and 61 females, mean age 47 years (range 15–77) were analyzed. Anti-thyroperoxidase (TPOAb) and anti-thyroglobulin antibodies (TgAb) were tested using radioimmunoassay. Free thyroxine (FT4) and free triiodothyronine (FT3) and thyroid-stimulating hormone (TSH) serum levels were measured using electro-immunochemiluminescence (ECLIA, Elecsys Roche). Clinical variables, including tender and swollen joint count, erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), rheumatoid factor (RF), anti-cyclic citrullinated peptide antibody (anti-CCP) and antinuclear antibodies (ANA) were also evaluated. Statistics were performed by the SPSS statistical software for Windows.

Results: Twenty-six patients (37%) with RA were positive for TPOAb and 16 (23%) for TgAb. In 5 (7.1%) patients TSH level was slightly elevated, ranging between 4.52 and 15.65 UI/ml. The increase of TSH levels was associated with normal FT4 in 3 cases (4.2%) and with reduced FT4 in 2 cases (2.8%). One patient (1.5%) had low TSH serum value along with normal FT4. No differences in clinical and serological data between anti-thyroid positive and negative patients were observed.

Conclusion: Our study shows an increased prevalence of anti-thyroid antibodies in RA patients with a low prevalence of hormonal alterations. However, anti-thyroid antibodies do not seem to identify any peculiar RA phenotype.  相似文献   
994.
European Child & Adolescent Psychiatry - Attention-Deficit/Hyperactivity Disorder (ADHD) comprises disturbances in attention, emotional regulation, and reward-related processes. In spite of the...  相似文献   
995.
996.
997.
International Journal of Legal Medicine - In literature, 3D-3D superimposition has been widely recognized as a valid method for personal identification. However, very little information is...  相似文献   
998.
Early life is a sensitive period, in which enhanced neural plasticity allows the developing brain to adapt to its environment. This plasticity can also be a risk factor in which maladaptive development can lead to long-lasting behavioral deficits. Here, we test how early-life exposure to the selective-serotonin-reuptake-inhibitor (SSRI), fluoxetine, affects motivation, and dopaminergic signaling in adulthood. We show for the first time that mice exposed to fluoxetine in the early postnatal period exhibit a reduction in effort-related motivation. These mice also show blunted responses to amphetamine and reduced dopaminergic activation in a sucrose reward task. Interestingly, we find that the reduction in motivation can be rescued in the adult by administering bupropion, a dopamine-norepinephrine reuptake inhibitor used as an antidepressant and a smoke cessation aid but not by fluoxetine. Taken together, our studies highlight the effects of early postnatal exposure of fluoxetine on motivation and demonstrate the involvement of the dopaminergic system in this process.SIGNIFICANCE STATEMENT The developmental period is characterized by enhanced plasticity. During this period, environmental factors have the potential to lead to enduring behavioral changes. Here, we show that exposure to the SSRI fluoxetine during a restricted period in early life leads to a reduction in adult motivation. We further show that this reduction is associated with decreased dopaminergic responsivity. Finally, we show that motivational deficits induced by early-life fluoxetine exposure can be rescued by adult administration of bupropion but not by fluoxetine.  相似文献   
999.
Transmembrane channel-like protein isoform 1 (TMC1) is a major component of the mechano-electrical transducer (MET) channel in cochlear hair cells and is subject to numerous mutations causing deafness. We report a new dominant human deafness mutation, TMC1 p.T422K, and have characterized the homologous mouse mutant, Tmc1 p.T416K, which caused deafness and outer hair cell (OHC) loss by the fourth postnatal week. MET channels showed decreased Ca2+ permeability and resting open probability, but no change in single-channel conductance or expression. Three adjacent deafness mutations are TMC1 p.L416R, p.G417R, and p.M418K, the last homologous to the mouse Beethoven that exhibits similar channel effects. All substitute a positive for a neutral residue, which could produce charge screening in the channel pore or influence binding of an accessory subunit. Channel properties were compared in mice of both sexes between dominant (Tmc1 p.T416K, Tmc1 p.D569N) and recessive (Tmc1 p.W554L, Tmc1 p.D528N) mutations of residues near the putative pore of the channel. Tmc1 p.W554L and p.D569N exhibit reduced maximum current with no effect on single-channel conductance, implying a smaller number of channels transported to the stereociliary tips; this may stem from impaired TMC1 binding to LHFPL5. Tmc1 p.D528N, located in the pore''s narrowest region, uniquely caused large reductions in MET channel conductance and block by dihydrostreptomycin (DHS). For Tmc1 p.T416K and Tmc1 p.D528N, transduction loss occurred between P15 and P20. We propose two mechanisms linking channel mutations and deafness: decreased Ca2+ permeability, common to all mutants, and decreased resting open probability in low Ca2+, confined to dominant mutations.SIGNIFICANCE STATEMENT Transmembrane channel-like protein isoform 1 (TMC1) is thought to be a major component of the mechanotransducer channel in auditory hair cells, but the protein organization and channel structure are still uncertain. We made four mouse lines harboring Tmc1 point mutations that alter channel properties, causing hair cell degeneration and deafness. These include a mouse homolog of a new human deafness mutation pT416K that decreased channel Ca2+ permeability by introducing a positively-charged amino acid in the putative pore. All mutations are consistent with the channel structure predicted from modeling, but only one, p.D528N near the external face of the pore, substantially reduced channel conductance and Ca2+ permeability and virtually abolished block by dihydrostreptomycin (DHS), strongly endorsing its siting within the pore.  相似文献   
1000.
Journal of Neurology - The ataxias are a group of disorders that manifest with balance, movement, speech and visual problems. They can arise due to dysfunction of the cerebellum, the vestibular...  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