全文获取类型
收费全文 | 12616篇 |
免费 | 993篇 |
国内免费 | 385篇 |
专业分类
13994篇 |
出版年
2023年 | 103篇 |
2022年 | 203篇 |
2021年 | 304篇 |
2020年 | 247篇 |
2019年 | 283篇 |
2018年 | 336篇 |
2017年 | 277篇 |
2016年 | 381篇 |
2015年 | 588篇 |
2014年 | 654篇 |
2013年 | 823篇 |
2012年 | 919篇 |
2011年 | 846篇 |
2010年 | 542篇 |
2009年 | 422篇 |
2008年 | 632篇 |
2007年 | 609篇 |
2006年 | 565篇 |
2005年 | 522篇 |
2004年 | 489篇 |
2003年 | 481篇 |
2002年 | 403篇 |
2001年 | 329篇 |
2000年 | 329篇 |
1999年 | 278篇 |
1998年 | 124篇 |
1997年 | 89篇 |
1996年 | 77篇 |
1995年 | 61篇 |
1994年 | 91篇 |
1993年 | 64篇 |
1992年 | 163篇 |
1991年 | 148篇 |
1990年 | 132篇 |
1989年 | 155篇 |
1988年 | 126篇 |
1987年 | 112篇 |
1986年 | 105篇 |
1985年 | 99篇 |
1984年 | 70篇 |
1983年 | 73篇 |
1982年 | 46篇 |
1979年 | 52篇 |
1977年 | 75篇 |
1976年 | 47篇 |
1975年 | 43篇 |
1974年 | 56篇 |
1973年 | 41篇 |
1971年 | 40篇 |
1969年 | 40篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
141.
Marino-Merlo Francesca Papaianni Emanuela Maugeri Teresa L. Zammuto Vincenzo Spanò Antonio Nicolaus Barbara Poli Annarita Di Donato Paola Mosca Claudia Mastino Antonio Gugliandolo Concetta 《Applied microbiology and biotechnology》2017,101(20):7487-7496
Applied Microbiology and Biotechnology - Herpes simplex virus type 1 (HSV-1) is responsible of common and widespread viral infections in humans through the world, and of rare, but extremely severe,... 相似文献
142.
Generation of a transgenic mouse model with chondrocyte-specific and tamoxifen-inducible expression of Cre recombinase 总被引:2,自引:0,他引:2
Chen M Lichtler AC Sheu TJ Xie C Zhang X O'Keefe RJ Chen D 《Genesis (New York, N.Y. : 2000)》2007,45(1):44-50
Postnatal cartilage development and growth are regulated by key growth factors and signaling molecules. To fully understand the function of these regulators, an inducible and chondrocyte-specific gene deletion system needs to be established to circumvent the perinatal lethality. In this report, we have generated a transgenic mouse model (Col2a1-CreER(T2)) in which expression of the Cre recombinase is driven by the chondrocyte-specific col2a1 promoter in a tamoxifen-inducible manner. To determine the specificity and efficiency of the Cre recombination, we have bred Col2a1-CreER(T2) mice with Rosa26R reporter mice. The X-Gal staining showed that the Cre recombination is specifically achieved in cartilage tissues with tamoxifen-induction. In vitro experiments of chondrocyte cell culture also demonstrate the 4-hydroxy tamoxifen-induced Cre recombination. These results demonstrate that Col2a1-CreER(T2) transgenic mice can be used as a valuable tool for an inducible and chondrocyte-specific gene deletion approach. 相似文献
143.
Carlotta Giromini Raffaella Rebucci Eleonora Fusi Luciana Rossi Francesca Saccone Antonella Baldi 《Cell biology and toxicology》2016,32(3):249-258
This study aimed to investigate the in vitro damage induced by ochratoxin A (OTA) in BME-UV1 and MDCK epithelial cells. Both cells lines were treated with OTA (0 up to 10 μg/mL), and cell viability (MTT assay), membrane stability (lactate dehydrogenase (LDH) release assay) and apoptotic cell rate (Tunel assay) were investigated. Further, the effect of the incubation with OTA has been evaluated at DNA level by the determination of DNA integrity, by the quantification of DNA adduct formation (8-hydroxy-2′-deoxyguanosine (8-OHdG)) and by the assessment of the global DNA methylation status (5-methyl-cytosine (5-mC)). The obtained results showed that after 24 h of OTA treatment, BME-UV1 cell viability was reduced in a dose-dependent way. OTA significantly (P?<?0.05) increased LDH release in BME-UV1 cells at all concentrations tested. OTA (1.25 μg/mL) induced 35 % LDH release in MDCK cells (P?<?0.05). A significant (P?<?0.05) change in percentages of apoptotic BME-UV1 (10?±?0.86) and MDCK (25?±?0.88) cells was calculated when the cells were co-incubated with OTA. The level of 8-OHdG adduct formation was significantly (P?<?0.05) increased in BME-UV1 cells treated with 1.25 μg/mL of OTA. The results of the present study suggest that a different mechanism of action may occur in these cell lines. 相似文献
144.
L-Propionyl-carnitine as superoxide scavenger, antioxidant, and DNA cleavage protector 总被引:5,自引:0,他引:5
Vanella A Russo A Acquaviva R Campisi A Di Giacomo C Sorrenti V Barcellona ML 《Cell biology and toxicology》2000,16(2):99-104
L-Propionylcarnitine, a propionyl ester of L-carnitine, increases the intracellular pool of L-carnitine. It exhibits a high
affinity for the enzyme carnitine acetyltransferase (CAT) and, thus, is readily converted into propionyl-coenzyme A and free
carnitine.
It has been reported that L-propionylcarnitine possesses a protective action against heart ischemia–reperfusion injury; however,
the antioxidant mechanism is not yet clear. L-Propionylcarnitine might reduce the hydroxyl radical production in the Fenton
system, by chelating the iron required for the generation of hydroxyl radicals. To obtain a better insight into the antiradical
mechanism of L-propionylcarnitine, the present research analyzed the superoxide scavenging capacity of L-propionylcarnitine
and its effect on linoleic acid peroxidation. In addition, the effect of L-propionylcarnitine against DNA cleavage was estimated
using pBR322 plasmid. We found that L-propionylcarnitine showed a dose-dependent free-radical scavenging activity. In fact,
it was able to scavenge superoxide anion, to inhibit the lipoperoxidation of linoleic acid, and to protect pBR322 DNA from
cleavage induced by H2O2 UV-photolysis.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
145.
Di Chen Chan Wu Shaowei Zhao Qing Geng Yu Gao Xin Li Yang Zhang Zhaohui Wang 《PLoS genetics》2014,10(11)
In regenerative tissues, one of the strategies to protect stem cells from genetic aberrations, potentially caused by frequent cell division, is to transiently expand the stem cell daughters before further differentiation. However, failure to exit the transit amplification may lead to overgrowth, and the molecular mechanism governing this regulation remains vague. In a Drosophila mutagenesis screen for factors involved in the regulation of germline stem cell (GSC) lineage, we isolated a mutation in the gene CG32364, which encodes a putative RNA-binding protein (RBP) and is designated as tumorous testis (tut). In tut mutant, spermatogonia fail to differentiate and over-amplify, a phenotype similar to that in mei-P26 mutant. Mei-P26 is a TRIM-NHL tumor suppressor homolog required for the differentiation of GSC lineage. We found that Tut binds preferentially a long isoform of mei-P26 3′UTR, and is essential for the translational repression of mei-P26 reporter. Bam and Bgcn are both RBPs that have also been shown to repress mei-P26 expression. Our genetic analyses indicate that tut, bam, or bgcn is required to repress mei-P26 and to promote the differentiation of GSCs. Biochemically, we demonstrate that Tut, Bam, and Bgcn can form a physical complex in which Bam holds Tut on its N-terminus and Bgcn on its C-terminus. Our in vivo and in vitro evidence illustrate that Tut acts with Bam, Bgcn to accurately coordinate proliferation and differentiation in Drosophila germline stem cell lineage. 相似文献
146.
147.
148.
阿特拉津降解菌ATR3的分离鉴定与土壤修复 总被引:1,自引:0,他引:1
阿特拉津因效率高、价格低廉,是我国玉米田施用最广泛的除草剂之一,但其结构稳定,残留时间长,因此对生态环境和人类健康造成了一定的危害。从长期受阿特拉津污染的玉米田土壤中筛选并鉴定阿特拉津降解菌,明确其在不同类型土壤中的去除能力。对分离出的阿特拉津降解菌ATR3进行生理生化分析和16S rRNA序列鉴定,确定菌株ATR3为节杆菌属(Arthrobacter sp.)。该菌株以阿特拉津为唯一氮源,培养48 h后对1 000 mg/L阿特拉津的去除率达到97%以上。敏感作物盆栽试验结果表明,阿特拉津在棕壤上去除最快,褐土次之,黑土最慢,说明阿特拉津在土壤中的去除过程与土壤本身的理化性质呈相关关系。同时,该菌株处理14 d后,能明显恢复玉米的各项生物学指标,说明该菌株对阿特拉津污染土壤具有良好的修复能力。为阿特拉津降解菌剂的推广利用提供参考。 相似文献
149.
Alessandra Micera Barbara Stampachiacchiere Antonio Di Zazzo Roberto Sgrulletta Magdalena Cortes Eduardo Maria Normando Alessandro Lambiase Stefano Bonini 《PloS one》2015,10(11)
Objective
In a previous study, we reported the upregulation of Nerve Growth Factor (NGF) and trkANGFR expression in Ocular Cicatricial Pemphigoid (OCP), an inflammatory and remodeling eye disease. Herein, we hypothesize a potential NGF-driven mechanism on fibroblasts (FBs) during OCP remodeling events. To verify, human derived OCP-FBs were isolated and characterized either at baseline or after NGF exposure.Materials and Methods
Conjunctival biopsies were obtained from 7 patients having OCP and 6 control subjects (cataract surgery). Both conjunctivas and primary FB cultures were characterised for αSMA, NGF and trkANGFR/p75NTR expression. Subcultures were exposed to NGF and evaluated for αSMA, NGF, trkANGFR/p75NTR expression as well as TGFβ1/IL4 release. For analysis, early and advanced subgroups were defined according to clinical parameters.Results
OCP-conjunctivas showed αSMA-expressing FBs and high NGF levels. Advanced OCP-FBs showed higher αSMA expression associated with higher p75NTR and lower trkANGFR expression, as compared to early counterparts. αSMA expression was in keeping with disease severity and correlated to p75NTR. NGF exposure did not affect trkANGFR levels in early OCP-FBs while decreased both αSMA/p75NTR expression and TGFβ1/IL4 release. These effects were not observed in advanced OCP-FBs.Conclusions
Taken together, these data are suggestive for a NGF/p75NTR task in the potential modulation of OCP fibrosis and encourages further studies to fully understand the underlying mechanism occurring in fibrosis. NGF/p75NTR might be viewed as a potential therapeutic target. 相似文献150.
Annunziata Mauro Alessandra Martelli Paolo Berardinelli Valentina Russo Nicola Bernabò Oriana Di Giacinto Mauro Mattioli Barbara Barboni 《PloS one》2014,9(4)