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   847篇
  免费   55篇
  国内免费   6篇
耳鼻咽喉   6篇
儿科学   46篇
妇产科学   2篇
基础医学   159篇
口腔科学   4篇
临床医学   64篇
内科学   136篇
皮肤病学   1篇
神经病学   113篇
特种医学   72篇
外国民族医学   3篇
外科学   132篇
综合类   23篇
预防医学   28篇
眼科学   5篇
药学   51篇
中国医学   1篇
肿瘤学   62篇
  2024年   2篇
  2023年   7篇
  2022年   12篇
  2021年   30篇
  2020年   24篇
  2019年   19篇
  2018年   25篇
  2017年   11篇
  2016年   27篇
  2015年   35篇
  2014年   42篇
  2013年   48篇
  2012年   79篇
  2011年   70篇
  2010年   44篇
  2009年   39篇
  2008年   40篇
  2007年   44篇
  2006年   38篇
  2005年   51篇
  2004年   44篇
  2003年   35篇
  2002年   30篇
  2001年   15篇
  2000年   19篇
  1999年   11篇
  1998年   9篇
  1997年   5篇
  1996年   5篇
  1995年   7篇
  1994年   2篇
  1993年   2篇
  1992年   9篇
  1991年   2篇
  1990年   1篇
  1989年   5篇
  1988年   4篇
  1987年   2篇
  1986年   4篇
  1984年   1篇
  1982年   1篇
  1980年   1篇
  1979年   2篇
  1970年   1篇
  1967年   1篇
  1961年   1篇
  1928年   1篇
  1915年   1篇
排序方式: 共有908条查询结果,搜索用时 15 毫秒
81.
ABSTRACTBackground: People with dementia in care homes are at risk of having their views ignored and decisions are often made on their behalf by care home staff and family carers. The aim of this study was to compare the ratings of needs of older people with dementia living in care homes, as assessed by the older person themselves, a family caregiver, and the staff of the care home.Method: The Camberwell Assessment of Need for the Elderly (CANE) was completed for 238 residents with dementia by care staff. In addition, 149 users and 81 family caregivers also completed the assessment of the person's met and unmet needs.Results: Many users were able to report their met and unmet needs despite having moderately severe dementia. The views of the person with dementia were commonly in agreement with the staff and family carers' views. However, user and carer pairs had the lowest average percentage agreement of 63% compared to that of 77% between user and staff pairs. In particular, users reported relatively higher unmet needs for psychological distress, company and information, and high unmet needs for daytime activities and eyesight/hearing problems.Conclusions: Users' views on their needs should be sought even when the person has dementia and lives in a care home. Reliance solely on assessment by staff or carers may lead to under recognition of unmet needs.  相似文献   
82.
Atherosclerosis may cause severe stenosis of the arteries supplying the brain, which induces chronic cerebral hypoperfusion. Although an infarction often occurs in this area, it is uncertain how brain vessels respond to the chronic hypoperfusion or how the vascular responses are related to stroke severity when the area has been subjected to severe ischemia. To address these uncertainties, we induced chronic cerebral hypoperfusion in Sprague-Dawley rats with a bilateral common carotid artery ligation (BCAL). A middle cerebral artery occlusion/reperfusion (MCAO/R) was introduced with a nylon suture four weeks after either BCAL (BCAL-MCAO) or a sham operation (Sham-MCAO). Motor disability scores and infarct sizes, based on 2,3,5-triphenyltetrazolium chloride staining, were significantly reduced with BCAL-MCAO treatment compared with sham-MCAO treatment (P<0.01). The diameters of the posterior cerebral, posterior communicating, and basilar arteries on the brain surface were larger and more tortuous in BCAL-treated rats (P<0.01). The density of large capillary- and arteriole-sized vessels in the brain parenchyma also increased in BCAL-treated rats (P<0.05). Strokes were less severe when the vicinity subjected to infarction was preconditioned with chronic cerebral hypoperfusion. Increasing the vascular reserve with adaptive vascular remodeling may have contributed to this response.  相似文献   
83.
84.
IntroductionPreservation of the cavernous nerves (CNs) during radical prostatectomy is crucial for the patient's erectile function. Despite advances in operative technique, the majority of men report compromised erectile function postprostatectomy or complete loss of potency due to CN trauma even with nerve-sparing modifications.AimThis study was designed to investigate whether repeated dosing of udenafil, a phosphodiesterase type 5 inhibitor, helps to improve erectile function after CN injury.MethodsUsing the CN crush injury model, 8-week-old male Sprague Dawley rats were divided into the following groups; sham-operated group, bilateral CN crush injury exposed to either no udenafil (vehicle) or udenafil (5, 20 mg/kg) daily for two different durations (4 and 8 weeks, p.o.).Main Outcome MeasuresAt both time points, CN electrical stimulation was used to assess erectile function by measuring the intracavernous pressure. The expressions of hypoxia-inducible factor 1-alpha (HIF-1α), transforming growth factor-beta (TGF-β1), nerve growth factor (NGF), endothelin B receptor (ETB), endothelial nitric oxide synthase (eNOS), neuronal nitric oxide synthase (nNOS), and sonic hedgehog homolog (SHH) in penile tissue were examined. Immunohistochemical antibody staining was performed for NGF, eNOS, nNOS, CD31, and alpha-smooth muscle actin (α-SMA). Additionally, terminal deoxynucleotidyl transferase-mediated nick-end labeling assay was performed to quantify apoptosis and the tissue slides were stained for Masson's trichrome to assess the smooth muscle/collagen ratio.ResultsUdenafil improved erectile function in a dose- and time-dependent manner with the maximum erectile function recovery achieved by 20 mg/kg udenafil at an 8-week time point. CN injury increased the expression of HIF-1α, TGF-β1, NGF, and ETB, however, decreased the expression of eNOS, nNOS, and SHH. Udenafil significantly suppressed these alterations. The results from the histological analyses show that udenafil markedly reduces apoptosis induced by CN injury and augments the smooth muscle/collagen ratio.ConclusionsCN injury induces significantly impaired erectile function and altered gene/protein expression. Chronic administration of udenafil preserves erectile function and has a beneficial role against the pathophysiological consequences of CN injury. Lee C-H, Kim H-S, Goo M-J, Kang K-K, Ahn B-O, Kim SH, and Yang D-Y. Chronic administration of udenafil, a selective phosphodiesterase type 5 inhibitor, promotes erectile function recovery in an animal model of bilateral cavernous nerve crush injury.  相似文献   
85.
Lee CK  Tay LL  Ng WH  Ng I  Ang BT 《Surgical neurology》2008,70(3):274-7; discussion 277-8
BACKGROUND: This study aimed to evaluate 2 commonly used posterior approach entry points for ventricular cannulation and the ideal trajectories using 3-dimensional virtual reality technology. METHODS: Magnetic resonance imaging data of 10 patients without gross ventricular dilatation or distortion were retrieved and reconstructed. A stereoscopic 3-dimensional preoperative planning system was used to designate the entry points. Various trajectories were simulated. The ideal trajectory was determined as the one that provided direct entry into the atrium or body of the lateral ventricle en route to the ipsilateral frontal horn. RESULTS: Magnetic resonance imaging data sets from 10 patients were used. For the entry point 6 cm above and 4 cm lateral to the inion (Frazier's point), ideal cannulation was achieved for all 10 patients when the selected target was 4 cm above the contralateral medial canthus. When the contralateral medial canthus was targeted, 5 patients had successful outcomes. There were only 3 satisfactory outcomes each when the ipsilateral medial canthus and glabella were targeted. The target 2 cm above the glabella yielded 2 satisfactory outcomes. The entry point 3 cm above and 2 cm lateral to the inion (Dandy's point) had 10 satisfactory outcomes when the target point was 2 cm above the glabella. All the other target points, namely, ipsilateral medial canthus, contralateral medial canthus, 4 cm above the contralateral medial canthus and glabella yielded poor results. CONCLUSIONS: For satisfactory placement when entering via Frazier's point, the best trajectory target would be 4 cm above the contralateral medial canthus. When entering via Dandy's point, the best target would be 2 cm above the glabella.  相似文献   
86.
This study investigated the preventive effect of Saururus chinensis Baill against renal damage induced by a high-fructose diet in rats. The rats (n = 30) were fed either a cornstarch-based (65%), high-fructose (65%), or high-fructose (64.5%) diet with 0.5% S. chinensis Baill extract for 10 weeks. Twenty-four hour urine collections were obtained and the animals were sacrificed after an overnight fast. Serum urea and creatinine and urine albumin were measured using colorimetric methods, and creatinine clearance was determined. In addition, thiobarbituric acid reactive substances (TBARS), reduced glutathione (GSH), and the activity of superoxide dismutase (SOD) in the kidney were determined. Kidney samples were also examined histologically. The fructose-fed rats showed renal dysfunction, indicated by decreased creatinine clearance, increased albumin in the urine, and increased urea and creatinine in the serum. These renal function parameters were comparable to control levels in rats that consumed S. chinensis Baill. Fructose consumption increased renal TBARS and reduced GSH and SOD activity, whereas these levels were near-normal in the rats consuming S. chinensis Baill. The kidneys of fructose-fed rats showed glomerular basement membrane thickening, mesangial matrix expansion, and tubule dilation. These pathological changes were not seen in the rats that consumed S. chinensis Baill. Therefore, S. chinensis Baill effectively alleviated fructose-induced renal damage in these rats, at least partially due to antioxidant activity.  相似文献   
87.
The number of patients who suffer from vertigo or dizziness becomes greater during the sixth and seventh decades of life and is now increasing to total, which could be related to recent longer life expectancy. Pertinent medical care should be given to those patients to better obtain so-called quality of life (QOL), and this could be attained with the help of accurate diagnosis. In general,accurate diagnosis is made by thorough neurotological examinations.  相似文献   
88.
N‐glycosylation status of purified β‐haptoglobin from sera of 17 patients, and from sera of 14 healthy volunteer subjects, was compared by blotting with various lectins and antibodies. Patients in this study were diagnosed as having colon cancer through histological examination of each tumor tissue by biopsy. Blotting index of serum β‐haptoglobin with Aleuria aurantia lectin (AAL) was clearly higher for cancer patients than for healthy subjects. No such distinction was observed for blotting with three other lectins and two monoclonal antibodies. To determine tumor‐associated reactivity of AAL binding as compared to inflammatory processes in colonic tissues, β‐haptoglobin separated from sera of 5 patients with Crohn's disease (CD), and 4 patients with ulcerative colitis (UC), was studied. All these cases, except one case of UC, showed AAL index lower than that in cancer cases, similarly to healthy subjects. The higher AAL binding of β‐haptoglobin in colon cancer patients than in healthy subjects appeared to be due to α‐L‐fucosyl residue, since it was eliminated by bovine kidney α‐fucosidase treatment. N‐linked glycans of serum haptoglobin from colon cancer patients vs. healthy subjects were released by N‐glycanase, fluorescence‐labeled, and subjected to normal‐phase high performance liquid chromatography (NP‐HPLC). Glycan structures were determined based on glucose unit (GU) values and their changes upon sequential treatment with various exoglycosidases. Glycosyl sequences and their branching status of glycans from 14 cases of serum β‐haptoglobin were characterized. The identified glycans were sialylated or nonsialylated, bi‐antennary or tri‐antennary structures, with or without terminal fucosylation.  相似文献   
89.
Apolipoprotein J (apoJ), also known as clusterin and SP-40,40, binds soluble beta-amyloid (Aβ and is up-regulated in the Alzheimer’s disease (AD) brain. In the present study we classified apoJ-immunopositive Aβ deposits in AD temporal cortex, and found apoJ-immunoreactive plaques were often associated with dystrophic neurites. Quantitative immunohistochemical analysis of five AD brains showed that 29% of Aβ deposited in the parenchyma was associated with apoJ. Of Aβ deposits with apoJ immunopositivity, 71% were associated with phospho-tau-positive dystrophic neurites in the surrounding tissue. Conversely, 64% of phospho-tau-labeled neuritic deposits were labeled with apoJ. ApoJ was found at the core of these deposits, and co-localized with the amyloid staining agent thioflavine-S. To test the direct effects of apoJ on tau metabolism, we treated cells in culture with apoJ-containing conditioned media, and we injected apoJ-containing media into the rat hippocampus. Using both systems, we observed increases in levels of tau and phosphorylated tau. Our findings demonstrate that apoJ immunopositivity strongly correlates with the presence of amyloid and associated neuritic dystrophy in the neuropil of AD temporal cortex, and supports a model where extracellular apoJ facilitates the conversion of diffuse Aβ deposits into amyloid and enhances tau phosphorylation in neurites surrounding these plaques.  相似文献   
90.
For the prevention of coronary restenosis, estrogen was coupled onto a metallic stent and in vitro release of estrogen was investigated. Estrogen was introduced to the metal surface using a hydrolysable covalent bond for local sustained delivery of drug as follows: (i) the stainless steel (SS) surface was activated with silane by plasma polymerization, (ii) the activated surface (SS-Si surface) was treated with acrylic acid by plasma polymerization (SS-Si-AAc surface), and (iii) 17beta-estradiol (E2) was covalently linked to the carboxyl group on that surface (SS-Si-AAc-E2 surface). The modified surfaces were characterized by X-ray photoelectron spectroscopy (XPS), Fourier transform infrared (FT-IR) spectroscopy, and water contact angle measurement. The amount of E2 was measured by UV-visible spectrophotometry and high performance liquid chromatography (HPLC). The in vitro release profile of E2 demonstrated sustained release of E2 in aqueous buffer. In summary, a novel method of immobilizing estrogen onto a metallic stent surface using plasma polymerization has been developed. The obtained results attest to the usefulness of the estrogen-releasing stent for preventing restenosis.  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