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   375篇
  免费   33篇
  国内免费   1篇
耳鼻咽喉   5篇
儿科学   9篇
妇产科学   6篇
基础医学   72篇
口腔科学   45篇
临床医学   23篇
内科学   75篇
皮肤病学   4篇
神经病学   13篇
特种医学   10篇
外科学   23篇
综合类   11篇
预防医学   18篇
眼科学   8篇
药学   24篇
中国医学   3篇
肿瘤学   60篇
  2023年   1篇
  2022年   10篇
  2021年   26篇
  2020年   8篇
  2019年   8篇
  2018年   13篇
  2017年   5篇
  2016年   10篇
  2015年   8篇
  2014年   21篇
  2013年   22篇
  2012年   32篇
  2011年   22篇
  2010年   19篇
  2009年   13篇
  2008年   16篇
  2007年   21篇
  2006年   23篇
  2005年   27篇
  2004年   27篇
  2003年   17篇
  2002年   10篇
  2001年   6篇
  2000年   4篇
  1999年   6篇
  1998年   3篇
  1997年   2篇
  1996年   4篇
  1995年   1篇
  1994年   1篇
  1993年   4篇
  1992年   4篇
  1991年   3篇
  1990年   1篇
  1989年   2篇
  1988年   1篇
  1985年   1篇
  1981年   2篇
  1979年   1篇
  1978年   1篇
  1977年   1篇
  1976年   1篇
  1969年   1篇
排序方式: 共有409条查询结果,搜索用时 15 毫秒
1.
Isolated primary amyloid tumor of bone is rare; however, preoperative diagnosis can be rewarding because the prognosis is excellent. There are no clinical or roentgenographic criteria that can establish this diagnosis. There are few previous reports of fine-needle aspiration (FNA) where diagnosis of amyloidoma was made retrospectively. They describe the presence of extracellular hyaline material along with plasma cells and lymphocytes. A 35-year-old female was referred to the FNA clinic with swelling in the right upper chest wall. Radiologic findings revealed a destructive lytic lesion involving the bodies of D1 and D2 vertebrae with extension into surrounding soft tissue. Repeated FNA smears were hypocellular but had abundant homogeneous flocculent material, which stained positive with Congo red. A few plasma cells and foreign-body giant cells were also seen. We conclude that preoperative FNA cytology diagnosis of amyloid tumor is possible. Hypocellular smears with flocculent material, plasma cells, and foreign-body giant cells in absence of granulation tissue should suggest the diagnosis.  相似文献   
2.
3.
Subcondylar fracture of the mandible accounts for 25–35% of all mandibular fractures. In the past, most subcondylar fractures were managed non-surgically. The traditional method of fixation for subcondylar fractures uses two miniplates; however some bench studies have reported that trapezoidal plates are superior. The aim of this study was to compare the outcomes of subcondylar fractures fixed either with two non-parallel straight miniplates or with one trapezoidal plate. A randomized clinical trial was designed and implemented. Fifty-two consecutive patients with subcondylar fractures were recruited. All patients underwent surgery via a retromandibular approach. The time taken for fixation of the plate after fracture reduction and postoperative outcomes and complications were compared between the groups. The trapezoidal plates were superior in terms of ease of adaptation and time taken for fixation (P =  0.0001). Plate fracture was observed only in the two miniplates group, in four (16%) patients. Outcomes were similar in the two groups in terms of occlusion, mouth opening, protrusion, and lateral excursion. In conclusion, both systems – two miniplates and the trapezoidal plate – provide functionally stable fixation. The outcome was significantly better for the trapezoidal plate than for two miniplates regarding the time taken for insertion and ease of adaptation, but not for other parameters.  相似文献   
4.
Background

MCPH1 is a proximal regulator of DNA damage response pathway that is involved in recruitment of phosphorylated ATM to double-stranded DNA breaks.

Methods

To understand the importance of MCPH1 and ATM in deregulation of DNA damage response pathway in breast carcinoma, we studied m-RNA expression and genetic/epigenetic alterations of these genes in primary breast carcinoma samples.

Results

Our study revealed reduced expression (mRNA/protein) and high alterations (deletion/methylation) (96 %, 121 of 126) of MCPH1 and ATM. Mutation was, however, rare in inactivation of MCPH1. In immunohistochemical analysis, reduced protein expression of MCPH1, ATM and p-ATM were concordant with their molecular alterations (P = 0.03–0.01). Alterations of MCPH1 and deletion of ATM were significantly high in estrogen/progesterone receptor–negative than estrogen/progesterone receptor–positive breast carcinoma samples compared to early or late age of onset tumors, indicating differences in pathogenesis of the molecular subtypes (P = 0.004–0.01). These genes also showed differential association with tumor stage, grade and lymph node status in different subtypes of breast carcinoma (P = 0.00001–0.01). Their coalterations showed significant association with tumor progression and prognosis (P = 0.003–0.05). Interestingly, patients with alterations of these genes or MCPH1 alone had poor outcome after treatment with DNA-interacting drugs and/or radiation (P = 0.01–0.05).

Conclusions

Inactivation of MCPH1-ATM-associated DNA damage response pathway might have an important role in the development of breast carcinoma with diagnostic, prognostic and therapeutic implications.

  相似文献   
5.
To perform sputum analysis for verification of pulmonary changes in premenopausal rural Indian women chronically exposed to biomass smoke during cooking.Three consecutive morning sputum samples were collected from 196 women (median age 34 years) cooking with biomass and 149 age-matched control women cooking with cleaner fuel liquefied petroleum gas. Smears made on slides were stained with Papanicolaou and Perl's Prussian blue. Airway oxidative stress was estimated as reactive oxygen species (ROS) generation (by flow cytometry) and superoxide dismutase (SOD) level (by spectrophotometry) in sputum cells. Airway inflammation was measured as sputum levels of interleukin (IL)-6, -8 and tumor necrosis factor- alpha (TNF-α). Particulate matter of diameter less than 10 (PM10) was measured using laser photometer while benzene exposure was monitored by measuring trans, trans-muconic acid (t,t-MA) in urine by HPLC-UV. Compared with control, sputum of biomass users contained more neutrophils, lymphocytes, eosinophils, alveolar macrophages, and showed presence of ciliocytophthoria, Charcot-Leyden crystals, Curschmann's spiral. ROS generation was increased by 2-fold while SOD was depleted by 31% in biomass users. They also had higher sputum levels of IL-6, -8 and TNF-α. Levels of PM10 and t,t-MA were 2.9- and 5.8-times higher in biomass-using women. PM10 and t,t-MA levels were positively associated with cellular changes in the sputum, markers of airway inflammation, and oxidative stress. Cooking with biomass alters sputum cytology, and increases airway inflammation and oxidative stress that might result in further amplification of the tissue damaging cascade in women chronically exposed to biomass smoke.  相似文献   
6.
7.
Carbohydrate functionalization of nanoparticles allows for targeting of C-type lectin receptors. This family of pattern recognition receptors expressed on innate immune cells, such as macrophages and dendritic cells, can be used to modulate immune responses. In this work, the in vivo safety profile of carbohydrate-functionalized polyanhydride nanoparticles was analyzed following parenteral and intranasal administration in mice. Polyanhydride nanoparticles based on 1,6-bis-(p-carboxyphenoxy)hexane and 1,8-bis-(p-carboxyphenoxy)-3,6-dioxaoctane were used. Nanoparticle functionalization with di-mannose (specifically carboxymethyl-α-d-mannopyranosyl-(1,2)-d-mannopyranoside), galactose (specifically carboxymethyl-β-galactoside), or glycolic acid induced no adverse effects after administration based on histopathological evaluation of liver, kidneys, and lungs. Regardless of the polymer formulation, there was no evidence of hepatic or renal damage or dysfunction observed in serum or urine samples. The histological profile of cellular infiltration and the cellular distribution and kinetics in the lungs of mice administered with nanoparticle treatments followed similar behavior as that observed in the lungs of animals administered with saline. Cytokine and chemokine profiles in bronchoalveolar lavage fluid indicated surface chemistry dependence on modest secretion of IL-6, IP-10, and MCP-1; however, there was no evidence of any deleterious histopathological changes. Based on these analyses, carbohydrate-functionalized nanoparticles are safe for in vivo applications. These results provide foundational information towards the evaluation of the capabilities of these surface-modified nanoparticles as vaccine delivery formulations.KEY WORDS: biocompatibility, carbohydrate, nanoparticles, polyanhydride, safety  相似文献   
8.
In previous work, our laboratory developed a Drosophila model for studying the adverse effects of fungal volatile organic compounds (VOCs) emitted by growing cultures of molds. In this report, we have extended these studies and compared the toxic effects of fungal VOCs emitted from living cultures of four molds isolated after Hurricane Katrina from a flooded home in New Orleans. Strains of Aspergillus, Mucor, Penicillium, and Trichoderma were grown with wild‐type larvae and the toxic effects of volatile products on the developmental stages of Drosophila larvae were evaluated. Furthermore, heterozygous mutants of Drosophila carrying the apoptotic genes, reaper and dronc, were used to assess the role of apoptosis in fungal VOCs mediated toxicity. Third‐instar larvae of Drosophila carrying these apoptotic genes were exposed to fungal VOCs emitted from growing mold cultures for 10 days. The larval strains carrying apoptopic genes survived longer than the control wild type larvae; moreover, of those that survived, heterozygous reaper and dronc strains progressed to pupae and adult phases more rapidly, suggesting that fungal VOCs may induce apoptotic changes in flies. These data lend support to the use of Drosophila as an inexpensive and genetically versatile toxicological model to investigate the mechanistic basis for some of the human illnesses/symptoms associated with exposure to mold‐contaminated indoor air, especially after hurricanes. © 2013 Wiley Periodicals, Inc. Environ Toxicol 30: 614–620, 2015.  相似文献   
9.
The method of DNA cyclization kinetics reveals special properties of the TATAAACGCC sequence motif found in DNA sequences that have high affinity for core histones. Replacement of 30 bp of generic DNA by three 10-bp repeats of the motif in small cyclization constructs increases cyclization rates by two orders of magnitude. We document a 13 degrees bend in the motif and characterize the direction of curvature. The bending force constant is smaller by nearly 2-fold and there is a 35% decrease in the twist modulus, relative to generic DNA. These features are the likely source of the high affinity for bending around core histones to form nucleosomes. Our results establish a protocol for determination of the ensemble-averaged global solution structure and mechanical properties of any approximately 10-bp DNA sequence element of interest, providing information complementary to that from NMR and crystallographic structural studies.  相似文献   
10.
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