全文获取类型
收费全文 | 1026篇 |
免费 | 63篇 |
国内免费 | 1篇 |
专业分类
1090篇 |
出版年
2024年 | 1篇 |
2023年 | 11篇 |
2022年 | 41篇 |
2021年 | 46篇 |
2020年 | 61篇 |
2019年 | 106篇 |
2018年 | 71篇 |
2017年 | 61篇 |
2016年 | 55篇 |
2015年 | 55篇 |
2014年 | 53篇 |
2013年 | 93篇 |
2012年 | 85篇 |
2011年 | 58篇 |
2010年 | 46篇 |
2009年 | 41篇 |
2008年 | 41篇 |
2007年 | 44篇 |
2006年 | 24篇 |
2005年 | 24篇 |
2004年 | 27篇 |
2003年 | 11篇 |
2002年 | 13篇 |
2000年 | 2篇 |
1999年 | 3篇 |
1998年 | 3篇 |
1997年 | 4篇 |
1996年 | 2篇 |
1995年 | 3篇 |
1989年 | 1篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1980年 | 1篇 |
1974年 | 1篇 |
排序方式: 共有1090条查询结果,搜索用时 15 毫秒
61.
Javad Amini Mahabadi Abolfazl Aazami Tameh Sayyed Alireza Talaei Mohammad Karimian Tahereh Rahiminia Seyed Ehsan Enderami Seyed Mohammad Gheibi Hayat Hossein Nikzad 《Journal of cellular biochemistry》2020,121(3):2159-2169
Numerous reagents were employed for differentiating induced pluripotent stem cells (iPSCs) into male germ cells; however, the induction procedure was ineffective. The aim of this study was to improve the in vitro differentiation of mice iPSCs (miPSCs) into male germ cells with retinoic acid (RA) and progesterone (P). miPSCs were differentiated to embryoid bodies (EBs) in suspension with RA with or without progesterone for 0, 4, and 7 days. Then, the expression of certain genes at different stages of male germ cell development including Ddx4 (pre meiosis), Stra8 (meiosis), AKAP3 (post meiosis), and Mvh protein was examined in RNA and/or protein levels by real-time polymerase chain reaction or flow cytometry, respectively. The Stra8 gene expression increased in the RA groups on all days. But, expression of this gene declined in RA + P groups. In addition, an increased expression of Ddx4 gene was observed on day 0 in the P group. Also, a significant upregulation was observed in the expression of AKAP3 gene in the RA + P group on days 0 and 4. However, gene expression decreased in P and RA groups on day 7. The expression of Mvh protein significantly increased in the RA group on day 7. The Mvh expression was also enhanced in the P group on day 4, but it decreased on day 7, while this protein upregulated on day 0 and 7 in the RA + P group. The miPSCs have the capacity for in vitro differentiation into male germ cells by RA and/or progesterone. However, the effects of these inducers depend on the type of combination and an effective time. 相似文献
62.
Maryam Sadeghzadeh Alireza Shirpoor Roya Naderi Fatemeh Kheradmand Farzaneh H. Gharalari Mahrokh Samadi Naser Khalaji Rasool Gharaaghaji 《Molecular reproduction and development》2019,86(6):624-631
Chronic alcohol ingestion causes sexual dysfunction, impairs sperm motility and fertility, and changes semen quality. Considering the key role of epididymis in sperm development, the aim of the present study was to evaluate the effects of long‐term ethanol consumption on epididymis changes, including alterations in β‐defensin isoform gene expression, oxidative stress, and pathological changes, such as cell proliferation and fibrosis in the epididymis of rats. In this study, male Wistar rats were equally divided into control and ethanol (4.5 g/kg BW) groups. After six weeks of treatment, the results revealed the proliferation of epididymis cells, fibrosis in the epididymis tissue, and a significant rise in the level of 8‐OHdG and nicotinamide adenine dinucleotide phosphate (NADPH) oxidase in the ethanol group, compared with the control group. Moreover, the ethanol group showed an increase in the gene expression of epididymal β‐defensin isoforms 15 and 21 and a reduction in the gene expression of β‐defensin isoforms 27 and 30, compared with the controls. These findings indicate that ethanol‐induced epididymal damage and sperm abnormalities might be partly associated with changes in β‐defensin isoforms and epididymal structure, mediated by the increased activities of 8‐OHdG and NADPH oxidase. 相似文献
63.
Maliheh Barazandeh Tehrani Zahra Rezaei Mehdi Asadi Hossein Behnammanesh Hamid Nadri Fatemeh Afsharirad Alireza Moradi Bagher Larijani Maryam Mohammadi‐Khanaposhtani Mohammad Mahdavi 《化学与生物多样性》2019,16(7)
A new series of coumarin‐3‐carboxamide‐N‐morpholine hybrids 5a – 5l was designed and synthesized as cholinesterases inhibitors. The synthetic approach for title compounds was started from the reaction between 2‐hydroxybenzaldehyde derivatives and Meldrum's acid to afford corresponding coumarin‐3‐carboxylic acids. Then, amidation of the latter compounds with 2‐morpholinoethylamine or N‐(3‐aminopropyl)morpholine led to the formation of the compounds 5a – 5l . The in vitro inhibition screen against acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE) revealed that most of the synthesized compounds had potent AChE inhibitory while their BuChE inhibitions are moderate to weak. Among them, propylmorpholine derivative 5g (N‐[3‐(morpholin‐4‐yl)propyl]‐2‐oxo‐2H‐chromene‐3‐carboxamide) bearing an unsubstituted coumarin moiety and ethylmorpholine derivative 5d (6‐bromo‐N‐[2‐(morpholin‐4‐yl)ethyl]‐2‐oxo‐2H‐chromene‐3‐carboxamide) bearing a 6‐bromocoumarin moiety showed the most activity against AChE and BuChE, respectively. The inhibitory activity of compound 5g against AChE was 1.78 times more than that of rivastigmine and anti‐BuChE activity of compound 5d is approximately same as rivastigmine. Kinetic and docking studies confirmed the dual binding site ability of compound 5g to inhibit AChE. 相似文献
64.
Andrew J. Burt H. Manilal William Gregory Perry Raja Khanal K. Peter Pauls James D. Kelly Alireza Navabi 《PloS one》2015,10(10)
Anthracnose, caused by Colletotrichum lindemuthianum, is an important fungal disease of common bean (Phaseolus vulgaris). Alleles at the Co–4 locus confer resistance to a number of races of C. lindemuthianum. A population of 94 F4:5 recombinant inbred lines of a cross between resistant black bean genotype B09197 and susceptible navy bean cultivar Nautica was used to identify markers associated with resistance in bean chromosome 8 (Pv08) where Co–4 is localized. Three SCAR markers with known linkage to Co–4 and a panel of single nucleotide markers were used for genotyping. A refined physical region on Pv08 with significant association with anthracnose resistance identified by markers was used in BLAST searches with the genomic sequence of common bean accession G19833. Thirty two unique annotated candidate genes were identified that spanned a physical region of 936.46 kb. A majority of the annotated genes identified had functional similarity to leucine rich repeats/receptor like kinase domains. Three annotated genes had similarity to 1, 3-β-glucanase domains. There were sequence similarities between some of the annotated genes found in the study and the genes associated with phosphoinositide-specific phosphilipases C associated with Co-x and the COK–4 loci found in previous studies. It is possible that the Co–4 locus is structured as a group of genes with functional domains dominated by protein tyrosine kinase along with leucine rich repeats/nucleotide binding site, phosphilipases C as well as β-glucanases. 相似文献
65.
Background
Hyperglycemia following solid organ transplant is common among patients without pre-existing diabetes mellitus (DM). Post-transplant hyperglycemia can occur once or multiple times, which if continued, causes new-onset diabetes after transplantation (NODAT).Objective
To study if the first and recurrent incidence of hyperglycemia are affected differently by immunosuppressive regimens, demographic and medical-related risk factors, and inpatient hyperglycemic conditions (i.e., an emphasis on the time course of post-transplant complications).Methods
We conducted a retrospective analysis of 407 patients who underwent kidney transplantation at Mayo Clinic Arizona. Among these, there were 292 patients with no signs of DM prior to transplant. For this category of patients, we evaluated the impact of (1) immunosuppressive drugs (e.g., tacrolimus, sirolimus, and steroid), (2) demographic and medical-related risk factors, and (3) inpatient hyperglycemic conditions on the first and recurrent incidence of hyperglycemia in one year post-transplant. We employed two versions of Cox regression analyses: (1) a time-dependent model to analyze the recurrent cases of hyperglycemia and (2) a time-independent model to analyze the first incidence of hyperglycemia.Results
Age (P = 0.018), HDL cholesterol (P = 0.010), and the average trough level of tacrolimus (P<0.0001) are significant risk factors associated with the first incidence of hyperglycemia, while age (P<0.0001), non-White race (P = 0.002), BMI (P = 0.002), HDL cholesterol (P = 0.003), uric acid (P = 0.012), and using steroid (P = 0.007) are the significant risk factors for the recurrent cases of hyperglycemia.Discussion
This study draws attention to the importance of analyzing the risk factors associated with a disease (specially a chronic one) with respect to both its first and recurrent incidence, as well as carefully differentiating these two perspectives: a fact that is currently overlooked in the literature. 相似文献66.
Gila Pirzad Jahromi Mostafa Ghanei Seyed Kazem Hosseini Alireza Shamsaei Mazaher Gholipourmalekabadi Ameneh Koochaki Nushin Karkuki Osguei Ali Samadikuchaksaraei 《PloS one》2015,10(12)
Purpose
In patients with short-term exposure to the sulfur mustard gas, the delayed cellular effects on lungs have not been well understood yet. The lung pathology shows a dominant feature consistent with obliterative bronchiolitis, in which fibroblasts play a central role. This study aims to characterize alterations to lung fibroblasts, at the cellular level, in patients with delayed respiratory complications after short-term exposure to the sulfur mustard gas.Methods
Fibroblasts were isolated from the transbronchial biopsies of patients with documented history of exposure to single high-dose sulfur mustard during 1985–7 and compared with the fibroblasts of control subjects.Results
Compared with controls, patients’ fibroblasts were thinner and shorter, and showed a higher population doubling level, migration capacity and number of filopodia. Sulfur mustard decreased the in vitro viability of fibroblasts and increased their sensitivity to induction of apoptosis, but did not change the rate of spontaneous apoptosis. In addition, higher expression of alpha smooth muscle actin showed that the lung''s microenvironment in these patients is permissive for myofibroblastic differentiation.Conclusions
These findings suggest that in patients under the study, the delayed pulmonary complications of sulfur mustard should be considered as a unique pathology, which might need a specific management by manipulation of cellular components. 相似文献67.
Simone?RiehlEmail author Marion?Benz Nicholas?J.?Conard Hojjat?Darabi Katleen?Deckers Hassan?Fazeli?Nashli Mohsen?Zeidi-Kulehparcheh 《Vegetation History and Archaeobotany》2012,21(2):95-106
The beginnings of agriculture throughout the Fertile Crescent are still not completely understood, particularly at the eastern end of the Fertile Crescent in the area of modern Iran. Archaeobotanical samples from Epipalaeolithic/PPNA Körtik Tepe in southeastern Turkey and from the Pre-Pottery Neolithic sites of Chogha Golan and East Chia Sabz in south western Iran were studied in order to define the status of cultivation at these sites. Preliminary results show the presence of abundant wild progenitor species of crops at the Iranian sites before 10600 cal. b.p., and very few wild progenitor species at Körtik Tepe dated to 11700–11250 cal. b.p. The Iranian sites also indicate size increase of wild barley grain across a sequence of 400 years through either cultivation or changing moisture conditions. 相似文献
68.
Vatandoost J Zomorodipour A Sadeghizadeh M Aliyari R Bos MH Ataei F 《Biotechnology progress》2012,28(1):45-51
The Drosophila γ-glutamyl carboxylase (dγC) has substrate recognition properties similar to that of the vertebrate γ-carboxylase (γC), and its carboxylated product yield, in vitro, was shown to be more than that obtained with the human enzyme. However, whether the Drosophila enzyme is able to γ-carboxylate the human vitamin K-dependent (VKD) proteins, such as the human coagulation factor IX (hFIX), as synthesized in cultured Drosophila cells was not known. To examine this possibility, the Drosophila Schnider (S2) cell line was transfected with a metallothionein promoter-regulated hFIX-expressing plasmid. After induction with copper ion, expression efficiency of the active hFIX was analyzed by performing enzyme-linked immunosorbent assey (ELISA) and coagulation test on the culture supernatant of the transfected S2 cells during 72 h of postinduction. In comparison with Chinese hamster ovary cell line, S2 cells showed higher (≈ 12-fold) expression level of the hFIX. The γ-carboxylation of the Drosophila-derived hFIX was confirmed by evaluation of the expressed protein, after being precipitated with barium citrate. The biological activity of the S2 cell-derived hFIX indicated the capability of S2 cells to fulfill the required γ-carboxylation of the expressed hFIX. Coexpression of the human γ-glutamyl carboxylases (hγC) was also shown to improve both expression and γ-carboxylation of the hFIX. This is the first in vivo data to describe the ability of the dγC to recognize the human-based propeptide as substrate, which is an essential step for production of biologically active γ-carboxylated VKD proteins. 相似文献
69.
Ashori A 《Bioresource technology》2008,99(11):4661-4667
Wood-plastic composite (WPC) is a very promising and sustainable green material to achieve durability without using toxic chemicals. The term WPCs refers to any composites that contain plant fiber and thermosets or thermoplastics. In comparison to other fibrous materials, plant fibers are in general suitable to reinforce plastics due to relative high strength and stiffness, low cost, low density, low CO2 emission, biodegradability and annually renewable. Plant fibers as fillers and reinforcements for polymers are currently the fastest-growing type of polymer additives. Since automakers are aiming to make every part either recyclable or biodegradable, there still seems to be some scope for green-composites based on biodegradable polymers and plant fibers. From a technical point of view, these bio-based composites will enhance mechanical strength and acoustic performance, reduce material weight and fuel consumption, lower production cost, improve passenger safety and shatterproof performance under extreme temperature changes, and improve biodegradability for the auto interior parts. 相似文献
70.
Arya A Haghjoo M Zahra E Heydari A Ali Sadr-Ameli M 《Indian pacing and electrophysiology journal》2004,4(4):217-220
Observation of Coincident arrhythmias is not uncommon but the co-existence of idiopathic verapamil sensitive left ventricular tachycardia (ILVT) with other arrhythmias is very rare. We hereby presented a 30 year old male patient with a history of frequent episodes of palpitations and sustained narrow complex tachycardia. During electrophysiologic study two arrhythmias, one with narrow complexes which was shown to be typical atrioventricular nodal re-entrant tachycardia and the other with wide QRS complexes and right bundle branch block and left axis morphology, compatible with ILVT, were inducible. Radiofrequency catheter ablation of both arrhythmias was done at two consecutive sessions. The patient has remained asymptomatic without antiarrhythmic therapy for the past six months. 相似文献