全文获取类型
收费全文 | 1324篇 |
免费 | 108篇 |
专业分类
1432篇 |
出版年
2023年 | 10篇 |
2022年 | 18篇 |
2021年 | 36篇 |
2020年 | 19篇 |
2019年 | 25篇 |
2018年 | 30篇 |
2017年 | 25篇 |
2016年 | 46篇 |
2015年 | 55篇 |
2014年 | 86篇 |
2013年 | 97篇 |
2012年 | 98篇 |
2011年 | 97篇 |
2010年 | 43篇 |
2009年 | 45篇 |
2008年 | 79篇 |
2007年 | 54篇 |
2006年 | 64篇 |
2005年 | 59篇 |
2004年 | 52篇 |
2003年 | 59篇 |
2002年 | 57篇 |
2001年 | 22篇 |
2000年 | 20篇 |
1999年 | 22篇 |
1998年 | 8篇 |
1997年 | 11篇 |
1996年 | 8篇 |
1995年 | 11篇 |
1994年 | 5篇 |
1992年 | 12篇 |
1991年 | 12篇 |
1990年 | 11篇 |
1989年 | 8篇 |
1988年 | 5篇 |
1987年 | 15篇 |
1986年 | 13篇 |
1985年 | 7篇 |
1984年 | 9篇 |
1983年 | 7篇 |
1981年 | 10篇 |
1980年 | 4篇 |
1979年 | 9篇 |
1978年 | 3篇 |
1975年 | 4篇 |
1974年 | 3篇 |
1973年 | 3篇 |
1968年 | 8篇 |
1967年 | 4篇 |
1965年 | 3篇 |
排序方式: 共有1432条查询结果,搜索用时 0 毫秒
91.
The aim of this work is to design and test an MRI probe (Gd-DOTAtyr-gal) able to report on the gene expression of β-galactosidase (β-Gal) in melanoma cells. The probe consists of a Gd-DOTA reporter bearing on its surface a tyrosine-galactose-pyranose functionality that, upon the release of the sugar moiety, readily transforms, in the presence of tyrosinase, into melanin oligomeric/polymeric mixture. The formation of Gd-DOTA-containing melanin oligomers and polymers is accompanied by a marked increase of the water proton relaxation rate. The steps involving the release of the galactose-pyranose group and the formation of the melanin-like structure have been carefully investigated in vitro by relaxometric and UV-vis measurements. Cellular uptake studies of Gd-DOTAtyr-gal by melanoma cells have shown that the probe enters the cells, and it appears not to be confined in endosomal vesicles. Using B16-F10LacZ transfected cells, the fast formation of paramagnetic melanin-Gd(III)-containing species has been assessed by the measurement of increased longitudinal relaxation rates of the cellular pellets suspensions. The in vitro results have been confirmed in in vivo MRI investigations on murine melanoma tumor bearing mice. Upon direct injection of Gd-DOTAtyr-gal, a good contrast is observed after 5 h post injection in B16-F10LacZ tumors, but not in B16-F10 tumors lacking the β-Gal enzyme. Gd-DOTAtyr-gal in combination with tyrosinase introduces a novel approach for the detection of β-Gal expression by MRI in vivo. 相似文献
92.
Barbosa LF de Souza MR Caritá RA Caputo F Denadai BS Greco CC 《Journal of strength and conditioning research / National Strength & Conditioning Association》2011,25(12):3385-3390
Barbosa, LF, de Souza, MR, Corrêa Caritá, RA, Caputo, F, Denadai, BS, and Greco, CC. Maximal lactate steady-state independent of recovery period during intermittent protocol. J Strength Cond Res 25(12): 3385-3390, 2011-The purpose of this study was to analyze the effect of the measurement time for blood lactate concentration ([La]) determination on [La] (maximal lactate steady state [MLSS]) and workload (MLSS during intermittent protocols [MLSSwi]) at maximal lactate steady state determined using intermittent protocols. Nineteen trained male cyclists were divided into 2 groups, for the determination of MLSSwi using passive (VO(2)max = 58.1 ± 3.5 ml·kg·min; N = 9) or active recovery (VO(2)max = 60.3 ± 9.0 ml·kg·min; N = 10). They performed the following tests, in different days, on a cycle ergometer: (a) Incremental test until exhaustion to determine (VO(2)max and (b) 30-minute intermittent constant-workload tests (7 × 4 and 1 × 2 minutes, with 2-minute recovery) to determine MLSSwi and MLSS. Each group performed the intermittent tests with passive or active recovery. The MLSSwi was defined as the highest workload at which [La] increased by no more than 1 mmol·L between minutes 10 and 30 (T1) or minutes 14 and 44 (T2) of the protocol. The MLSS (Passive-T1: 5.89 ± 1.41 vs. T2: 5.61 ± 1.78 mmol·L) and MLSSwi (Passive-T1: 294.5 ± 31.8 vs. T2: 294.7 ± 32.2 W; Active-T1: 304.6 ± 23.0 vs. T2: 300.5 ± 23.9 W) were similar for both criteria. However, MLSS was lower in T2 (4.91 ± 1.91 mmol·L) when compared with in T1 (5.62 ± 1.83 mmol·L) using active recovery. We can conclude that the MLSSwi (passive and active conditions) was unchanged whether recovery periods were considered (T1) or not (T2) for the interpretation of [La] kinetics. In contrast, MLSS was lowered when considering the active recovery periods (T2). Thus, shorter intermittent protocols (i.e., T1) to determine MLSSwi may optimize time of the aerobic capacity evaluation of well-trained cyclists. 相似文献
93.
Da Settimo F Primofiore G La Motta C Salerno S Novellino E Greco G Lavecchia A Laneri S Boldrini E 《Bioorganic & medicinal chemistry》2005,13(2):491-499
The 2,3-dihydrospiro[4H-thiopyrano[2,3-b]pyridin-4,4'-imidazolidine]-2',5'-dione 3 and its 7-methyl analogue 4 were synthesized and tested for their ability to inhibit aldose reductase (ALR2). To expand the structure-activity relationships, the sulfone 5 and the acetic acid derivative 7 were also prepared and tested. Compounds 3 and 4 proved to be potent ALR2 inhibitors, with IC50 values in the submicromolar range (0.96 and 0.94 microM, respectively) similar to that of sorbinil (0.65 microM). Moreover, compound 3 was found to be highly potent in preventing cataract development in severely galactosemic rats, like tolrestat, when administered as an eyedrop solution. Docking simulations of both R- and S-isomers of 3 into the ALR2 crystal structure were carried out to guide, prospectively, the design of new analogues. 相似文献
94.
Maria Eugenia Carlotti Elena Ugazio Simona Sapino Ivana Fenoglio Giovanna Greco Bice Fubini 《Free radical research》2013,47(3):312-322
TiO2 nanoparticles hazard is associated to their photocatalytic activity causing release of DNA damaging ROS (Reactive Oxygen Species), lipid peroxidation and skin damage. Various coatings have been proposed to minimize photocatalysis, while keeping the potential to block UV radiations. Uncoated and variously coated commercial nano-titania have been classified on the basis of UVB-induced lipoperoxidation of linoleic acid. A selection of the most and the least protective specimens was then examined by ESR (Electron Spin Resonance) to evidence the presence of surface paramagnetic centres and the release of ROS in aqueous suspensions (spin trapping). Paramagnetic centres and ROS were correlated with the extent of lipid peroxidation. When tested on porcine skin (mimicking the human one), titania acted as on linoleic acid. The combined use of lipid peroxidation of simple fatty acids with ESR analysis is here proposed as a possible screening tool for the evaluation of the potential toxicity of nano-titania in sunscreen preparations. 相似文献
95.
Multiparasitism involves competition between larvae inside the host. Telenomus podisi (Ashmead) and Trissolcus urichi (Crawford) (Hymenoptera: Platygastridae) are solitary egg parasitoids of Piezodorus guildinii Westwood (Hemiptera: Pentatomidae), an important soybean pest. Egg masses partially parasitized by one species were offered to females of the other species. Both species attacked randomly unparasitized and parasitized hosts. Emergence from multiparasitized eggs was greater for T. urichi than for T. podisi, although it was lower than emergence from eggs parasitized by T. urichi alone. Emergence of each species was independent of the order in which they parasitized and of time elapsed between ovipositions. Progeny sex ratio obtained from multiparasitized and from parasitized eggs were similar for both parasitoids. Our results suggest that T. urichi is a better intrinsic competitor than T. podisi for P. guildinii eggs. In the field, however, T. podisi was the dominant species, and T. urichi could be using other pentatomid eggs as resource. 相似文献
96.
Piero Ruggenenti Paolo Cravedi Eliana Gotti Annarita Plati Maddalena Maras Silvio Sandrini Nicola Bossini Franco Citterio Enrico Minetti Domenico Montanaro Ettore Sabadini Regina Tardanico Davide Martinetti Flavio Gaspari Alessandro Villa Annalisa Perna Francesco Peraro Giuseppe Remuzzi 《PLoS medicine》2021,18(6)
BackgroundWe compared protection of mycophenolate mofetil (MMF) and azathioprine (AZA) against acute cellular rejection (ACR) and chronic allograft nephropathy (CAN) in kidney transplant recipients on steroid-free, low-dose cyclosporine (CsA) microemulsion maintenance immunosuppression.Methods and findingsATHENA, a pragmatic, prospective, multicenter trial conducted by 6 Italian transplant centers, compared the outcomes of 233 consenting recipients of a first deceased donor kidney transplant induced with low-dose thymoglobulin and basiliximab and randomized to MMF (750 mg twice/day, n = 119) or AZA (75 to 125 mg/day, n = 114) added-on maintenance low-dose CsA microemulsion and 1-week steroid. In patients without acute clinical or subclinical rejections, CsA dose was progressively halved. Primary endpoint was biopsy-proven CAN. Analysis was by intention to treat.Participants were included between June 2007 and July 2012 and followed up to August 2016. Between-group donor and recipient characteristics, donor/recipient mismatches, and follow-up CsA blood levels were similar. During a median (interquartile range (IQR)) follow-up of 47.7 (44.2 to 48.9) months, 29 of 87 biopsied patients on MMF (33.3%) versus 31 of 88 on AZA (35.2%) developed CAN (hazard ratio (HR) [95% confidence interval (CI)]: 1.147 (0.691 to 1.904, p = 0.595). Twenty and 21 patients on MMF versus 34 and 14 on AZA had clinical [HR (95% CI): 0.58 (0.34 to 1.02); p = 0.057) or biopsy-proven subclinical [HR (95% CI): 1.49 (0.76 to 2.92); p = 0.249] ACR, respectively. Combined events [HR (95% CI): 0.85 (0.56 to 1.29); p = 0.438], patient and graft survival, delayed graft function (DGF), 3-year glomerular filtration rate (GFR) [53.8 (40.6;65.7) versus 49.8 (36.8;62.5) mL/min/1.73 m2, p = 0.50], and adverse events (AEs) were not significantly different between groups.Chronicity scores other than CAN predict long-term graft outcome. Study limitations include small sample size and unblinded design.ConclusionsIn this study, we found that in deceased donor kidney transplant recipients on low-dose CsA and no steroids, MMF had no significant benefits over AZA. This finding suggests that AZA, due to its lower costs, could safely replace MMF in combination with minimized immunosuppression.Trial registrationClinicalTrials.gov ; NCT00494741EUDRACT 2006-005604-14.Piero Ruggenenti and co-workers study maintenance immunosuppression in deceased-donor kidney transplantation. 相似文献
97.
Navaglia F Fogar P Greco E Basso D Stefani AL Mazza S Zambon CF Habeler W Altavilla G Amadori A Cecchetto A Plebani M 《The International journal of biological markers》2003,18(2):130-138
AIMS: The aims of this study were 1) to investigate the mRNA pattern of CD44 variants in three primary (MIA PaCa 2, PANC-1, PSN-1) and two metastatic (CAPAN-1, SUIT-2) pancreatic cancer (PC) cell lines; 2) to ascertain whether the genetic transfer of CD44s and CD44v10 modifies the adhesion of PC cells to the extracellular matrix (ECM) in vitro and their metastatic behavior in vivo. METHODS: CD44 mRNA analysis was done by means of RT-PCR. Adhesion to ECM the was assessed using coated microtiter plates. For the study of CD44v10 insertion in the CAPAN-1 line, liposome-mediated DNA transfer was used. SCID mice were employed for in vivo experiments. RESULTS: CD44v10 mRNA was not expressed by the CAPAN-1 nor by four of the six SUIT-2-derived clones. The stable expression of CD44v10 by modified CAPAN-1 significantly enhanced fibronectin adhesion. Mice without either liver or pancreatic metastases were more frequently found among the animals injected with modified (CD44v10 expressing) than with non-modified CAPAN-1. CONCLUSIONS: 1) It is possible to differentiate between metastatic and non-metastatic PC cells on the basis of CD44v10 expression; 2) CD44v10 seems to be involved in mediating fibronectin adhesion in vitro and in counteracting metastases in vivo. 相似文献
98.
99.
Plant Ecology - The distribution pattern of perennial native grasses in the dune systems of the Monte desert might be determined by the ability of plant roots to acquire water under drought... 相似文献
100.
Susan Costantini Francesca Capone Marco Miele Eliana Guerriero Maria Napolitano Giovanni Colonna Giuseppe Castello 《Bioinformation》2009,4(3):92-93
Cytokines are subdivided in 12 sub-families and are described as multi-functional
molecules that play an important biological activity in host defense system
against pathogens, in homeostasis, tissue repair, cell growth and development.
CytokineDB is an annotated database that collects biological information
regarding the cytokines family in human and will be periodically updated by
including new biological information. This database is freely available online
and can be accessed at the URL: http://www.cro-m.eu/CytokineDB/ 相似文献