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   620篇
  免费   28篇
  国内免费   4篇
耳鼻咽喉   1篇
儿科学   6篇
妇产科学   26篇
基础医学   98篇
口腔科学   6篇
临床医学   54篇
内科学   129篇
皮肤病学   4篇
神经病学   60篇
特种医学   37篇
外科学   113篇
综合类   2篇
一般理论   1篇
预防医学   35篇
眼科学   13篇
药学   38篇
中国医学   3篇
肿瘤学   26篇
  2023年   8篇
  2022年   12篇
  2021年   32篇
  2020年   22篇
  2019年   29篇
  2018年   15篇
  2017年   13篇
  2016年   11篇
  2015年   22篇
  2014年   26篇
  2013年   45篇
  2012年   71篇
  2011年   56篇
  2010年   36篇
  2009年   22篇
  2008年   29篇
  2007年   25篇
  2006年   33篇
  2005年   28篇
  2004年   33篇
  2003年   23篇
  2002年   22篇
  2001年   5篇
  2000年   8篇
  1999年   5篇
  1998年   4篇
  1997年   2篇
  1996年   2篇
  1994年   1篇
  1991年   2篇
  1985年   1篇
  1984年   1篇
  1983年   2篇
  1981年   1篇
  1980年   2篇
  1979年   1篇
  1975年   1篇
  1967年   1篇
排序方式: 共有652条查询结果,搜索用时 375 毫秒
51.
In this study, we report the molecular cytogenetic characterization of an acute myeloid leukemia with a der(Y)t(Y;1)(q12;q25) in bone marrow cells in a child with Klinefelter syndrome. Conventional cytogenetics demonstrated the unbalanced translocation, i.e., a trisomic 1q25-qter juxtaposed to Yq12 replaced the terminal segment of chromosome Y was acquired and present only on bone marrow cells. Fluorescence in situ hybridization showed that the breakpoint at 1q25 disrupted RABGAP1L, a strongly expressed gene in CFU-GEMM, erythroid cells, and megakaryocytes, while the Yq12 breakpoint fell within the heterochromatic region. As der(Y)t(Y;1)(q12;q25) was an isolated cytogenetic change, RABGAP1L rearrangement as well as gene(s) dosage effects correlated to 1q25-qter trisomy, and Yq12-qter loss may make a major contribution to leukemogenesis and/or disease progression. Maria Cristina Roberti and Roberta La Starza should be regarded as joint first authors.  相似文献   
52.
STUDY DESIGN: Retrospective review of 259 lumbar discectomies. OBJECTIVE: To compare rates of reoperation after subtotal discectomy versus established rates after fragment excision. SUMMARY OF BACKGROUND DATA: Herniated nucleus pulposes (HNP) and annular morphology influence rates of reherniation after discectomy. Certain patterns are linked to reherniation rates exceeding 20%. METHODS: We retrospectively reviewed 259 single-level lumbar discectomies performed between 1980 and 2005. Mean follow-up was 60.9 months. In each case, annulotomy and subtotal discectomy was performed in addition to excision of disc fragments. HNP morphology was classified according to the 4-part system of Carragee (type 1: fragment/fissure; type 2: fragment/defect; type 3: fragment/contained; type 4: no fragment/contained). Fisher exact test was used to compare our proportion of patients with reherniation and/or reoperation to Caragee's series in which only fragment excision was performed. RESULTS: Of 259 cases, 12 (4.5%) reoperations were performed. A significant difference in failure/reoperation rate was noted in type 2 herniations. There was a significantly lower rate of failure and reoperation for type 2 HNP after subtotal discectomy (3.4%) when compared with fragment excision alone (21.2%), P<0.003. CONCLUSIONS: Subtotal discectomy is an acceptable technique that decreases reherniation after lumbar discectomy.  相似文献   
53.
54.
It has been known for many years that plasma and tissues contain a variety of enzymes capable of metabolizing kinins. The aim of the present study was to evaluate, by means of functional studies in a capacitance vessel such as the human umbilical vein (HUV), the possible role played by the metallopeptidases angiotensin-converting enzyme (ACE), neutral endopeptidase (NEP), and aminopeptidase M (APM) as an inactivating pathway of the B1 receptor endogenous agonist des-Arg10-kallidin (DAKD). In HUV rings with and without endothelium, concentration-response curves (CRCs) to DAKD were determined after a 300-min incubation period, and enzymatic inhibitors were added to the organ baths 30 min before construction of the CRC. Presence of endothelial layer was confirmed by histological studies. There was a significant leftward shift observed in control HUV rings devoid of endothelium compared with intact tissues. Exposure to 1 μM captopril (ACE inhibitor) potentiated DAKD-elicited vasoconstrictor responses in HUV rings with endothelium while no such effect was observed in tissues devoid of endothelium. Application of 10 μM amastatin (APM inhibitor) induced a leftward shift of DAKD-elicited contractile responses in HUV with and without endothelium. On the other hand, 10 μM phosphoramidon (NEP inhibitor) showed no potentiating effect in HUV rings either with or without endothelium. However, under concurrent inhibition of ACE, NEP and APM, there was a higher potentiation of DAKD-elicited contractile responses compared with the effect observed with combined inhibition of ACE and APM. Moreover, when we evaluated contractile responses induced by Sar0-D-Phe8-des-Arg9-BK (a metabolically protected B1 receptor agonist), no potentiating effect was observed under triple enzymatic inhibition. In conclusion, in the present study for the first time, we demonstrated in a capacitance vessel, HUV, that metallopeptidases ACE, NEP and APM represent a relevant functional inactivation pathway of DAKD.  相似文献   
55.
56.
57.
58.
ABSTRACT: BACKGROUND: Few studies demonstrate effectiveness of therapies for oral rehabilitation of patients with cerebral palsy (CP), given the difficulties in chewing, swallowing and speech, besides the intellectual, sensory and social limitations. Due to upper airway obstruction, they are also vulnerable to sleep disorders. This study aims to assess the sleep variables, through polysomnography, and masticatory dynamics, using electromiography, before and after neuromuscular electrical stimulation, associated or not with low power laser (Gallium Arsenide- Aluminun, = 780nm) and LED ( = 660 nm) irradiation in CP patients. Methods/Design: 50 patients with CP, both gender, aged between 19 and 60 years will be enrolled in this study. The inclusion criteria are: voluntary participation, patient with hemiparesis, quadriparesis or diparetic CP, with ability to understand and respond to verbal commands. The exclusion criteria are: patients undergoing / underwent orthodontic, functional maxillary orthopedic or botulinum toxin treatment. Polysomnographic and surface electromyographic exams on masseter, temporalis and suprahyoid will be carry out in all sample. Questionnaire assessing oral characteristics will be applied. The sample will be divided into 5 treatment groups: Group 1: neuromuscular electrical stimulation; Group 2: laser therapy; Group 3: LED therapy; Group 4: neuromuscular electrical stimulation and laser therapy and Group 5: neuromuscular electrical stimulation and LED therapy. All patients will be treated during 8 consecutive weeks. After treatment, polysomnographic and electromiographic exams will be collected again. Discussion: This paper describes a five arm clinical trial assessing the examination of sleep quality and masticatory function in patients with CP under non-invasive therapies.  相似文献   
59.
ObjectiveThe use of anthropometric measurements to estimate the percentage of body fat (%BF) is easy and inexpensive. However, the accuracy of these methods in patients with 21-hydroxylase deficiency (21OHD) has not been explored. The objective of this study was to evaluate the accuracy of skinfold-based models, body mass index (BMI), and waist circumference (WC) in estimations of %BF using dual-energy X-ray absorptiometry (DXA) as the reference method in individuals with 21OHD.MethodsFifty-four 21OHD patients (32 women and 22 men), aged 7 to 20 y, were recruited for the study. DXA was used to determine %BF; four predictive skinfold equations, BMI, and WC were assessed for accuracy in determining %BF.ResultsAll predictive skinfold equations were highly associated (R, range: 0.82-0.89) with DXA %BF values. In women, BMI and WC showed moderate correlations (R = 0.69 for both BMI and WC) with DXA values. In contrast, among men there was a low explanatory power for BMI (13%) and WC (4%) and high errors (BMI, 6.9%; WC, 7.4%). All predictive equations significantly underestimated %BF (range of differences, ?4.1 to ?8.9) compared with DXA (women, 31.3 ± 6.1; men, 24.4 ± 7.3), and large limits of agreement were observed (range, ?15.3 to 1.7 and ?15.5 to 4.2 for women and men, respectively).ConclusionIn children and adolescents with 21OHD, %BF as estimated by skinfold measurements was associated more strongly with DXA-assessed %BF than both BMI and WC. However, still, the skinfold-based assessment underestimated DXA %BF and showed moderate agreement.  相似文献   
60.
Two new conifer morphospecies represented by a secondary xylem are reported for the Lower Cretaceous Baqueró Group (Santa Cruz Province, Argentina). Agathoxylon sp. is characterized by poorly defined growth rings, predominantly uniseriate pitting in the radial wall of the tracheids, cross fields with 1-6 pits and uniseriate rays. These features are shared with the leafy branches described for the unit as Araucaria grandifolia Feruglio emend. Del Fueyo and Archangelsky. The second taxon, Brachyoxylon sp. cf. B. boureaui, possesses poorly defined growth rings, mixed wood with predominantly uniseriate radial pitting, cross fields with 8-26 pits and uniseriate rays. These taxa represent the first fossil woods described for Baqueroan strata.  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