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   1239篇
  免费   88篇
  国内免费   56篇
电工技术   9篇
综合类   20篇
化学工业   581篇
金属工艺   45篇
机械仪表   21篇
建筑科学   120篇
能源动力   3篇
轻工业   199篇
水利工程   5篇
石油天然气   3篇
武器工业   1篇
无线电   60篇
一般工业技术   72篇
冶金工业   142篇
原子能技术   5篇
自动化技术   97篇
  2024年   4篇
  2023年   21篇
  2022年   226篇
  2021年   241篇
  2020年   68篇
  2019年   53篇
  2018年   30篇
  2017年   44篇
  2016年   29篇
  2015年   40篇
  2014年   55篇
  2013年   64篇
  2012年   48篇
  2011年   51篇
  2010年   52篇
  2009年   33篇
  2008年   41篇
  2007年   37篇
  2006年   36篇
  2005年   33篇
  2004年   30篇
  2003年   30篇
  2002年   16篇
  2001年   20篇
  2000年   5篇
  1999年   6篇
  1998年   6篇
  1997年   3篇
  1996年   3篇
  1995年   7篇
  1994年   2篇
  1993年   12篇
  1992年   4篇
  1991年   6篇
  1990年   3篇
  1988年   3篇
  1987年   1篇
  1986年   3篇
  1985年   2篇
  1984年   1篇
  1982年   1篇
  1980年   1篇
  1976年   2篇
  1964年   1篇
  1963年   1篇
  1962年   1篇
  1960年   2篇
  1959年   1篇
  1956年   2篇
  1955年   1篇
排序方式: 共有1383条查询结果,搜索用时 0 毫秒
101.
Mucopolysaccharidosis IIIA (MPS IIIA, Sanfilippo syndrome type A), a paediatric neurological lysosomal storage disease, is caused by impaired function of the enzyme N-sulfoglucosamine sulfohydrolase (SGSH) resulting in impaired catabolism of heparan sulfate glycosaminoglycan (HS GAG) and its accumulation in tissues. MPS IIIA represents a significant proportion of childhood dementias. This condition generally leads to patient death in the teenage years, yet no effective therapy exists for MPS IIIA and a complete understanding of the mechanisms of MPS IIIA pathogenesis is lacking. Here, we employ targeted CRISPR/Cas9 mutagenesis to generate a model of MPS IIIA in the zebrafish, a model organism with strong genetic tractability and amenity for high-throughput screening. The sgshΔex5−6 zebrafish mutant exhibits a complete absence of Sgsh enzymatic activity, leading to progressive accumulation of HS degradation products with age. sgshΔex5−6 zebrafish faithfully recapitulate diverse CNS-specific features of MPS IIIA, including neuronal lysosomal overabundance, complex behavioural phenotypes, and profound, lifelong neuroinflammation. We further demonstrate that neuroinflammation in sgshΔex5−6 zebrafish is largely dependent on interleukin-1β and can be attenuated via the pharmacological inhibition of Caspase-1, which partially rescues behavioural abnormalities in sgshΔex5−6 mutant larvae in a context-dependent manner. We expect the sgshΔex5−6 zebrafish mutant to be a valuable resource in gaining a better understanding of MPS IIIA pathobiology towards the development of timely and effective therapeutic interventions.  相似文献   
102.
Migraine, the leading cause of disability in the population aged below 50, is associated with functional gastrointestinal (GI) disorders (FGIDs) such as functional nausea, cyclic vomiting syndrome, and irritable bowel syndrome (IBS). Conversely, changes in intestinal GI transit may cause diarrhea or constipation and are a component of the autonomic symptoms associated with pre- and post-dorsal phases of migraine attack. These mutual relationships provoke a question on a common trigger in migraine and FGIDs. The kynurenine (l-kyn) pathway (KP) is the major route for l-tryptophan (l-Trp) metabolism and transforms l-Trp into several neuroactive compounds. Changes in KP were reported in both migraine and FGIDs. Migraine was largely untreatable, but several drugs approved lately by the FDA, including monoclonal antibodies for calcitonin gene-related peptide (CGRP) and its receptor, create a hope for a breakthrough in migraine treatment. Derivatives of l-kyn were efficient in pain relief with a mechanism including CGRP inhibition. KP products are important ligands to the aryl hydrocarbon receptor (AhR), whose activation is implicated in the pathogenesis of GI and migraine. Toll-like receptors (TLRs) may play a role in migraine and IBS pathogeneses, and KP metabolites detected downstream of TLR activation may be an IBS marker. The TLR4 signaling was observed in initiating and maintaining migraine-like behavior through myeloid differentiation primary response gene 88 (MyD88) in the mouse. The aim of this review is to justify the view that KP modulation may provide common triggers for migraine and FGIDs with the involvement of TLR, AhR, and MyD88 activation.  相似文献   
103.
In contrast to USH2A, variants in ADGRV1 are a minor cause of Usher syndrome type 2, and the associated phenotype is less known. The purpose of the study was to characterize the retinal phenotype of 18 ADGRV1 patients (9 male, 9 female; median age 52 years) and compare it with that of 204 USH2A patients (111 male, 93 female; median age 43 years) in terms of nyctalopia onset, best corrected visual acuity (BCVA), fundus autofluorescence (FAF), and optical coherence tomography (OCT) features. There was no statistical difference in the median age at onset (30 and 18 years; Mann–Whitney U test, p = 0.13); the mean age when 50% of the patients reached legal blindness (≥1.0 log MAR) based on visual acuity (64 years for both groups; log-rank, p = 0.3); the risk of developing advanced retinal degeneration (patch or atrophy) with age (multiple logistic regression, p = 0.8); or the frequency of cystoid macular edema (31% vs. 26%, Fisher’s exact test, p = 0.4). ADGRV1 and USH2A retinopathy were indistinguishable in all major functional and structural characteristics, suggesting that the loss of function of the corresponding proteins produces similar effects in the retina. The results are important for counseling ADGRV1 patients, who represent the minor patient subgroup.  相似文献   
104.
105.
Hutchinson–Gilford progeria syndrome (HGPS), or progeria, is an extremely rare disorder that belongs to the class of laminopathies, diseases characterized by alterations in the genes that encode for the lamin proteins or for their associated interacting proteins. In particular, progeria is caused by a point mutation in the gene that codifies for the lamin A gene. This mutation ultimately leads to the biosynthesis of a mutated version of lamin A called progerin, which accumulates abnormally in the nuclear lamina. This accumulation elicits several alterations at the nuclear, cellular, and tissue levels that are phenotypically reflected in a systemic disorder with important alterations, mainly in the cardiovascular system, bones, skin, and overall growth, which results in premature death at an average age of 14.5 years. In 2020, lonafarnib became the first (and only) FDA approved drug for treating progeria. In this context, the present review focuses on the different therapeutic strategies currently under development, with special attention to the new small molecules described in recent years, which may represent the upcoming first-in-class drugs with new mechanisms of action endowed with effectiveness not only to treat but also to cure progeria.  相似文献   
106.
107.
Severe periodontitis is prevalent in Down syndrome (DS). This study aimed to identify genetic variations associated with periodontitis in individuals with DS. The study group was distributed into DS patients with periodontitis (n = 50) and DS patients with healthy periodontium (n = 36). All samples were genotyped with the “Axiom Spanish Biobank” array, which contains 757,836 markers. An association analysis at the individual marker level using logistic regression, as well as at the gene level applying the sequence kernel association test (SKAT) was performed. The most significant genes were included in a pathway analysis using the free DAVID software. C12orf74 (rs4315121, p = 9.85 × 10−5, OR = 8.84), LOC101930064 (rs4814890, p = 9.61 × 10−5, OR = 0.13), KBTBD12 (rs1549874, p = 8.27 × 10−5, OR = 0.08), PIWIL1 (rs11060842, p = 7.82 × 10−5, OR = 9.05) and C16orf82 (rs62030877, p = 8.92 × 10−5, OR = 0.14) showed a higher probability in the individual analysis. The analysis at the gene level highlighted PIWIL, MIR9-2, LHCGR, TPR and BCR. At the signaling pathway level, PI3K-Akt, long-term depression and FoxO achieved nominal significance (p = 1.3 × 10−2, p = 5.1 × 10−3, p = 1.2 × 10−2, respectively). In summary, various metabolic pathways are involved in the pathogenesis of periodontitis in DS, including PI3K-Akt, which regulates cell proliferation and inflammatory response.  相似文献   
108.
周碧蓉  陈越峰  周娜  杨景 《金属学报》2013,18(9):1036-1039
目的: 探讨血清高敏C反应蛋白(hs-CRP)、组织蛋白酶S(CatS)与急性冠脉综合征的相关关系。方法: 选择53例急性冠脉综合征患者(ACS组),对照组36例,检测两组血清CatS、hs-CRP水平并进行比较。同时检测ACS组治疗后血清hs-CRP、CatS水平的变化。结果: ACS组在性别、年龄、吸烟、糖尿病、脑梗死、高血压患病率方面与对照组相比,差异无统计学意义(P>0.05);ACS组治疗前血清CatS水平为(0.51±0.03) nmol/L,hs-CRP为(10.21±5.03) mg/L,分别高于对照组的(0.43±0.04) nmol/L 和(3.64±1.87) mg/L,差异具有统计学意义(P<0.05); ACS组治疗后血清CatS、hs-CRP水平分别为(0.45±0.06) nmol/L 和(6.05±3.25) mg/L,较治疗前的(0.51±0.03) nmol/L 和(10.21±5.03) mg/L 明显降低,差异有统计学意义(P<0.05)。结论: ACS患者血清CatS及hs-CRP的水平的变化提示 CatS及hs-CRP可能在ACS发生发展过程中具有重要作用,推测 CatS可能作为ACS的一种新的生物标志物。  相似文献   
109.
为了对当前爆发流行的高致病性猪繁殖与呼吸系统综合症病毒建立快速准确的检测方法,根据该类病毒在Nsp2基因1594-1680处缺失87个碱基的特点,设计了一对特异性引物和一个Taqman探针,通过对反应条件的优化,建立了荧光定量PCR检测方法.该方法特异性强,灵敏度高,能很好地区分高致病性猪繁殖与呼吸系统综合症病毒和其它病毒,没有发现假阳性和假阴性现象,检测病毒滴度达到1TCID50.用该法对38份疑似样本进行检测,阳性率60.5%,与常规PCR法符合率100%.  相似文献   
110.
Consumption of pine nuts from the species of Pinus armandii has been reported to cause dysgeusia, commonly known as pine mouth, or pine nut syndrome (PNS). However, the number of reports on pine nut consumptions of the different species and PNS is limited. This leaves open the possibility that other pine species than P. armandii could be involved in PNS as well. This study investigated 18 samples involved in PNS and received at the Danish Veterinary and Food Administration in 2011 through 2012. Samples were subjected to gas chromatographic analysis of fatty acids. The content of 11 individual fatty acids was used together with the diagnostic index and the sum of Δ5-fatty acids as diagnostic parameters. Diagnostic parameters from samples were then compared to reference material and literature data to determine the species. In a limited number of samples, the diagnostic parameters matched neither our reference materials nor literature data. However, the morphology, the fatty acid analysis, and externally obtained DNA sequencing data suggest a P. armandii subspecies or a variety. With these possible P. armandii subspecies, P. armandii was identified in all analyzed samples. The application of principal component analysis (PCA) to the data set showed a satisfactory separation of the majority of the 13 pine species included in the study.  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