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   4475篇
  免费   432篇
  国内免费   8篇
耳鼻咽喉   42篇
儿科学   120篇
妇产科学   78篇
基础医学   610篇
口腔科学   115篇
临床医学   544篇
内科学   627篇
皮肤病学   109篇
神经病学   615篇
特种医学   281篇
外科学   597篇
综合类   165篇
一般理论   2篇
预防医学   360篇
眼科学   88篇
药学   264篇
  1篇
中国医学   25篇
肿瘤学   272篇
  2021年   45篇
  2020年   37篇
  2019年   51篇
  2018年   64篇
  2017年   41篇
  2016年   43篇
  2015年   65篇
  2014年   93篇
  2013年   123篇
  2012年   158篇
  2011年   153篇
  2010年   114篇
  2009年   112篇
  2008年   170篇
  2007年   191篇
  2006年   223篇
  2005年   201篇
  2004年   160篇
  2003年   163篇
  2002年   133篇
  2001年   133篇
  2000年   137篇
  1999年   121篇
  1998年   73篇
  1997年   93篇
  1996年   89篇
  1995年   82篇
  1994年   67篇
  1993年   64篇
  1992年   127篇
  1991年   106篇
  1990年   145篇
  1989年   123篇
  1988年   113篇
  1987年   112篇
  1986年   86篇
  1985年   105篇
  1984年   79篇
  1983年   71篇
  1982年   58篇
  1981年   54篇
  1980年   34篇
  1979年   53篇
  1978年   49篇
  1977年   33篇
  1976年   43篇
  1975年   36篇
  1974年   29篇
  1973年   37篇
  1972年   29篇
排序方式: 共有4915条查询结果,搜索用时 17 毫秒
1.
2.
3.
ABSTRACT

Background: In the context of a randomized controlled trial evaluating the efficacy of augmenting fluoxetine treatment in young adults with major depressive disorder (MDD) using a modified repeated partial sleep deprivation protocol contrasting 2 weeks of restricted time in bed (i.e., 6 h TIB) to no time in bed restriction (i.e., 8 h TIB) the study examines whether sleep duration and the timing of repeated partial sleep deprivation predicts patient-reported affect ratings.

Participants: Participants included 58 young adults with DSM-IV-diagnosed MDD.

Methods: Daily ratings of affect and sleep were collected during the first 2 weeks of initiating fluoxetine treatment, yielding 630 person-days. Actigraphy monitoring was employed to assess compliance with time in bed condition.

Results: Negative affect ratings and positivity ratios in the morning were more improved among participants assigned to the 6 h TIB condition compared to the 8 h TIB group. Participants whose bedtime was delayed by 2-h nightly demonstrated the most significant improvement in negative affect and positivity ratio during the first 2 weeks of fluoxetine therapy. Moreover, the trajectory of morning negative affect ratings in the first 2 weeks was predictive of remission after 4 weeks of fluoxetine therapy.

Conclusions: These findings suggest that monitoring changes in daily affect may be a valuable marker of early treatment response in young adults with MDD.  相似文献   
4.
Pituitary - Growth hormone-producing pituitary adenomas are divided into two clinically relevant histologic subtypes, densely (DG-A) and sparsely (SG-A) granulated. Histologic subtype was evaluated...  相似文献   
5.
6.
Background: Cystic fibrosis (CF) is challenged with pathophysiological barriers for effective airway drug-delivery. Hence, we standardized the therapeutic efficacy of the novel dendrimer-based autophagy-inducing anti-oxidant drug, cysteamine.

Research design and methods: Human primary-CF epithelial-cells, CFBE41o-cells were used to standardize the efficacy of the dendrimer-cystamine in correcting impaired-autophagy, rescuing ΔF508-CFTR and Pseudomonas-aeruginosa (Pa) infection.

Results: We first designed a novel cystamine-core dendrimer formulation (G4-CYS) that significantly increases membrane-ΔF508CFTR expression in CFBE41o-cells (p < 0.05) by forming its reduced-form cysteamine, in vivo. Additionally, G4-CYS treatment corrects ΔF508-CFTR-mediated impaired-autophagy as observed by a significant decrease (p < 0.05) in Ub-LC3-positive aggresome-bodies. Next, we verified that in non-permeabilized CFBE41o-cells, G4-CYS significantly (p < 0.05) induces ΔF508-CFTR’s forward-trafficking to the plasma membrane. Furthermore, cysteamine’s known antibacterial and anti-biofilm properties against Pa were enhanced as our findings demonstrate that both G4-CYS and its control DAB-core dendrimer, G4-DAB, exhibited significant (p < 0.05) bactericidal-activity against Pa. We also found that both G4-CYS and G4-DAB exhibit marked mucolytic-activity against porcine-mucus (p < 0.05). Finally, we demonstrate that G4-CYS not only corrects the autophagy-impairment by rescuing ΔF508-CFTR in CFBE41o-cells but also corrects the intrinsic phagocytosis defect (p < 0.05).

Conclusions: Overall, our data demonstrates the efficacy of novel cystamine-dendrimer formulation in rescuing ΔF508-CFTR to the plasma membrane and inhibiting Pa bacterial-infection by augmenting autophagy.  相似文献   

7.

Purpose

To quantify eating disorder (ED) stability and diagnostic transition among a community-based sample of adolescents and young adult females in the United States.

Methods

Using 11 prospective assessments from 9,031 U.S. females ages 9–15 years at baseline of the Growing Up Today Study, we classified cases of the following EDs involving bingeing and purging: bulimia nervosa (BN), binge ED, purging disorder (PD), and subthreshold variants defined by less frequent (monthly vs. weekly) bingeing and purging behaviors. We measured number of years symptomatic and probability of maintaining symptoms, crossing to another diagnosis, or resolving symptoms across consecutive surveys.

Results

Study lifetime disorder prevalence was 2.1% for BN and roughly 6% each for binge ED and PD. Most cases reported symptoms during only one survey year. Twenty-six percent of cases crossed between diagnoses during follow-up. Among participants meeting full threshold diagnostic criteria, transition from BN was most prevalent, crossing most frequently from BN to PD (12.9% of BN cases). Within each disorder phenotype, 20%–40% of cases moved between subthreshold and full threshold criteria across consecutive surveys.

Conclusions

Diagnostic crossover is not rare among adolescent and young adult females with an ED. Transition patterns from BN to PD add support for considering these classifications in the same diagnostic category of disorders that involve purging. The prevalence of crossover between monthly and weekly symptom frequency suggests that a continuum or staging approach may increase utility of ED classification for prognostic and therapeutic intervention.  相似文献   
8.
9.
10.
The genetic hallmark of epithelioid hemangioendothelioma (EHE) is a recurrent WWTR1‐CAMTA1 fusion, which is present in most cases bearing a conventional histology. A subset of cases is characterized by a distinct morphology and harbors instead of YAP1‐TFE3 fusion. Nevertheless, isolated cases lack these canonical fusions and remain difficult to classify. Triggered by an index case of a left atrial mass in a 76‐year‐old female with morphologic features typical of EHE, but which showed a WWTR1‐MAML2 fusion by targeted RNA sequencing, we searched our files for similar cases displaying alternative WWTR1 fusions. A total of 6 EHE cases were identified with variant WWTR1 fusions, four of them presenting within the heart. There were three females and three males, with a wide age range at diagnosis (21‐76 years, mean 62, median 69). The four cardiac cases occurred in older adults (mean age of 72, equal gender distribution); three involved the left atrium and one the right ventricle. One case presented in the vertebral bone and one in pelvic soft tissue. Microscopically, all tumors had morphologic features within the spectrum of classic EHE; two of the cases appeared overtly malignant. All cases were tested by FISH and four were investigated by targeted RNA sequencing. Two tumors harbored WWTR1‐MAML2 fusions, one WWTR1‐ACTL6A, and in three cases, no WWTR1 partner was identified. Of the four patients with follow‐up, two died of disease, one was alive with lung metastases, and the only patient free of disease was s/p resection of a T11 vertebral mass. Our findings report on additional genetic variants involving WWTR1 rearrangements, with WWTR1‐MAML2 being a recurrent event, in a small subset of EHE, which appears to have predilection for the heart.  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