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   614篇
  免费   29篇
  2024年   2篇
  2023年   11篇
  2022年   6篇
  2021年   19篇
  2020年   6篇
  2019年   16篇
  2018年   21篇
  2017年   15篇
  2016年   26篇
  2015年   35篇
  2014年   49篇
  2013年   60篇
  2012年   53篇
  2011年   73篇
  2010年   33篇
  2009年   27篇
  2008年   37篇
  2007年   38篇
  2006年   26篇
  2005年   18篇
  2004年   14篇
  2003年   13篇
  2002年   13篇
  2000年   2篇
  1999年   3篇
  1998年   1篇
  1996年   1篇
  1994年   1篇
  1992年   1篇
  1991年   2篇
  1989年   1篇
  1986年   1篇
  1985年   4篇
  1984年   3篇
  1982年   1篇
  1981年   2篇
  1979年   1篇
  1978年   1篇
  1976年   1篇
  1975年   1篇
  1972年   2篇
  1971年   1篇
  1969年   1篇
  1959年   1篇
排序方式: 共有643条查询结果,搜索用时 265 毫秒
11.
Members of the ADAM (a disintegrin and metalloprotease) family are type I transmembrane proteins involved in biological processes of proteolysis, cell adhesion, cell–matrix interaction, as well as in the intracellular signaling transduction. In the present study, expression patterns of seven members of the ADAM family were investigated at the early stages of the developing cochlea by in situ hybridization. The results show that each individual ADAM is expressed and regulated in the early developing cochlea. ADAM9, ADAM10, ADAM17, and ADAM23 are initially and widely expressed in the otic vesicle at embryonic day 2.5 (E2.5) and in the differential elements of the cochlear duct at E9, while ADAM12 is expressed in acoustic ganglion cells at E7. ADAM22 is detectable in cochlear ganglion cells as early as from E4 and in the basilar papilla from E7. Therefore, the present study extends our previous results and suggests that ADAMs also play a role in the early cochlear development.  相似文献   
12.
A series of some novel 1,3,5-triazine–Schiff base conjugates (132) have been synthesized and evaluated for their in vitro antimycobacterial activity against Mycobacterium tuberculosis H37Rv using Alamar Blue assay and the activity expressed as the minimum inhibitory concentration (MIC) in μg/mL. Compounds 4 (4-Methoxy-6-methyl-N-(3,4,5-trimethoxybenzylidene)-1,3,5-triazin-2-amine), 11 (4-Methoxy-6-methyl-N-(2-hydroxy-3-bromo-5-chloro-benzylidene)-1,3,5-triazin-2-amine) and 24 (4-Methoxy-6-methyl-N-(1-(2,5-dihydroxyphenyl)ethylidene)-1,3,5-triazin-2-amine) exhibited a significant activity at 3.125, 6.25 and 6.25 μg/mL, respectively, when compared with the antitubercular drugs such as ethambutol (3.125 μg/mL), pyrazinamide (6.25 μg/mL) and streptomycin (6.25 μg/mL) and it could be a potential starting point to develop new lead compounds in the fight against Mycobacterium tuberculosis H37Rv.  相似文献   
13.

BACKGROUND:

Mental retardation (MR) is a heterogeneous dysfunction of the central nervous system exhibiting complex phenotypes and has an estimated prevalence of 1-3% in the general population. However, in about 50% of the children diagnosed with any form of intellectual disability or developmental delay the cause goes undetected contributing to idiopathic intellectual disability.

MATERIALS AND METHODS:

A total of 122 children with developmental delay/MR were studied to identify the microscopic and submicroscopic chromosome rearrangements by using the conventional cytogenetics and multiplex ligation dependent probe amplification (MLPA) analysis using SALSA MLPA kits from Microbiology Research Centre Holland [MRC] Holland.

RESULTS:

All the recruited children were selected for this study, after thorough clinical assessment and metaphases prepared were analyzed by using automated karyotyping system. None was found to have chromosomal abnormality; MLPA analysis was carried out in all subjects and identified in 11 (9%) patients.

CONCLUSION:

Karyotype analysis in combination with MLPA assays for submicroscopic micro-deletions may be recommended for children with idiopathic MR.  相似文献   
14.
It is increasingly understood that gastrointestinal (GI) methanogens, including Methanobrevibacter smithii, influence host metabolism.

Objective:

Therefore, we compared M. smithii colonization and weight gain in a rat model under different dietary conditions.

Design and Methods:

Sprague‐Dawley rats were inoculated with M. smithii or vehicle (N = 10/group), fed normal chow until day 112 postinoculation, high‐fat chow until day 182, then normal chow until day 253. Thereafter, five rats from each group were fed high‐fat and normal chow until euthanasia.

Results:

Both groups exhibited M. smithii colonization, which increased following inoculation only for the first 9 days. Change to high‐fat chow correlated with significant increases in weight (P < 0.00001) and stool M. smithii (P < 0.01) in all rats, with stool M. smithi decreasing on return to normal chow. Rats switched back to high‐fat on day 253 further increased weight (P < 0.001) and stool M. smithii (P = 0.039). Euthanasia revealed all animals had higher M. smithii, but not total bacteria, in the small intestine than in the colon. Rats switched back to high‐fat chow had higher M. smithii levels in the duodenum, ileum, and cecum than those fed normal chow; total bacteria did not differ in any bowel segment. Rats which gained more weight had more bowel segments colonized, and the lowest weight recorded was in a rat on high‐fat chow which had minimal M. smithii colonization.

Conclusions:

We conclude that M. smithii colonization occurs in the small bowel as well as in the colon, and that the level and extent of M. smithii colonization is predictive of degree of weight gain in this animal model.  相似文献   
15.
GluN2A is the most abundant of the GluN2 NMDA receptor subunits in the mammalian CNS. Physiological and genetic evidence implicate GluN2A-containing receptors in susceptibility to autism, schizophrenia, childhood epilepsy and neurodevelopmental disorders such as Rett Syndrome. However, GluN2A-selective pharmacological probes to explore the therapeutic potential of targeting these receptors have been lacking. Here we disclose a novel series of pyrazine-containing GluN2A antagonists exemplified by MPX-004 (5-(((3-chloro-4-fluorophenyl)sulfonamido)methyl)-N-((2-methylthiazol-5-yl)methyl)pyrazine-2-carboxamide) and MPX-007 (5-(((3-fluoro-4-fluorophenyl)sulfonamido)methyl)-N-((2-methylthiazol-5-yl)methyl)methylpyrazine-2-carboxamide). MPX-004 and MPX-007 inhibit GluN2A-containing NMDA receptors expressed in HEK cells with IC50s of 79 nM and 27 nM, respectively. In contrast, at concentrations that completely inhibited GluN2A activity these compounds have no inhibitory effect on GluN2B or GluN2D receptor-mediated responses in similar HEK cell-based assays. Potency and selectivity were confirmed in electrophysiology assays in Xenopus oocytes expressing GluN2A-D receptor subtypes. Maximal concentrations of MPX-004 and MPX-007 inhibited ~30% of the whole-cell current in rat pyramidal neurons in primary culture and MPX-004 inhibited ~60% of the total NMDA receptor-mediated EPSP in rat hippocampal slices. GluN2A-selectivity at native receptors was confirmed by the finding that MPX-004 had no inhibitory effect on NMDA receptor mediated synaptic currents in cortical slices from GRIN2A knock out mice. Thus, MPX-004 and MPX-007 offer highly selective pharmacological tools to probe GluN2A physiology and involvement in neuropsychiatric and developmental disorders.  相似文献   
16.
Insulin resistance (IR) and type 2 diabetes mellitus (T2DM) have been found to be associated with postprandial hypertriglyceridemia (PPHTg). However, whether PPHTg can cause IR and diabetes is not clear. We therefore investigated the role of PPHTg in development of T2DM in rat model of T2DM. 96 male Wistar rats were randomized into four groups (24 rats each). Control Group A, high sucrose diet (HSD) Group B, HSD+Pioglitazone (10mg/kg/day) Group C and HSD+Atorvastatin (20mg/kg/day) Group D. Fat and glucose tolerance tests were done at regular intervals in all groups besides insulin and body weight measurement. At 26 weeks, low dose streptozotocin (15mg/kg,i.p.) was given to half of the rats. All rats were followed up till 48 weeks. PPHTg developed as early as week 2 in Group B and stabilized by week 14. Group B displayed highest PPHTg compared to other groups. Atorvastatin treatment (Group D) abolished PPHTg which became comparable to controls, pioglitazone treatment partially blunted PPHTg resulting in intermediate PPHTg. Group B with highest PPHTg showed highest subsequent IR, glucose intolerance (GI) and highest incidence of prediabetes at week 26 and diabetes at week 34 and 46 compared to other groups. Group D rats displayed lower IR, GI, low incidence of prediabetes and diabetes at these time points compared to Groups B and C. ROC analysis showed that triglyceride area under the curve of each time point significantly predicts the risk of diabetes. Present study provides the evidence that PPHTg predicts the development of IR, GI and T2DM in rat model of diet induced T2DM.  相似文献   
17.
18.
19.
As a continuation of effort to improve our high flow on-line bioanalytical approach for high-throughput quantification of drugs and metabolites in plasma by high-throughput liquid chromatography tandem mass spectrometry (HTLC-MS/MS), we have developed a simple, sensitive and reliable method for simultaneous quantification of loratadine and desloratadine in human plasma. We have performed on-line coupling of extraction with Cyclone P 50 mm x 0.5 mm 50 microm HTLC column and chromatographic separation is performed with Zorbax XDB C18 50 mm x 2.1 mm 5 microm, followed by quantification with mass detector. The method is validated and showed good performances in terms of linearity, sensitivity, precision, accuracy and stability. A marked improvement in sample throughput efficiency is realized with this method and the proposed method will be useful for pharmacokinetic and/or bioequivalence studies.  相似文献   
20.
Calcium boro fluoro zinc phosphate glasses modified using alkali oxide and doped with Nd3+ and Er3+ ions with the chemical composition of 69.5 (B2O3) + 10 (P2O5) + 10 (CaF2) + 5 (ZnO) + 5 (Na2O/Li2O/K2O) + 0.5 (Er2O3/Nd2O3) were prepared using a conventional melt quenching technique. The results of X-ray diffraction patterns indicated the amorphous nature of all the prepared glasses. The visible–near-infrared red (NIR) absorption spectra of these glasses were analyzed systematically. The NIR emission spectra of Er3+ and Nd3+:calcium boro fluoro zinc phosphate glasses showed prominent emission bands at 1536 nm (4I13/24I15/2) and 1069 nm (4F3/24I11/2) respectively with λexci = 514.5 nm (Ar+ laser) as the excitation source.  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