全文获取类型
收费全文 | 2162篇 |
免费 | 127篇 |
国内免费 | 2篇 |
出版年
2023年 | 10篇 |
2022年 | 22篇 |
2021年 | 43篇 |
2020年 | 22篇 |
2019年 | 41篇 |
2018年 | 44篇 |
2017年 | 38篇 |
2016年 | 63篇 |
2015年 | 99篇 |
2014年 | 107篇 |
2013年 | 144篇 |
2012年 | 171篇 |
2011年 | 164篇 |
2010年 | 98篇 |
2009年 | 92篇 |
2008年 | 133篇 |
2007年 | 124篇 |
2006年 | 117篇 |
2005年 | 101篇 |
2004年 | 111篇 |
2003年 | 96篇 |
2002年 | 98篇 |
2001年 | 21篇 |
2000年 | 15篇 |
1999年 | 18篇 |
1998年 | 11篇 |
1997年 | 19篇 |
1996年 | 14篇 |
1995年 | 5篇 |
1994年 | 13篇 |
1993年 | 14篇 |
1992年 | 18篇 |
1991年 | 6篇 |
1990年 | 21篇 |
1989年 | 16篇 |
1988年 | 11篇 |
1987年 | 10篇 |
1986年 | 9篇 |
1985年 | 13篇 |
1984年 | 13篇 |
1983年 | 11篇 |
1982年 | 9篇 |
1981年 | 7篇 |
1980年 | 7篇 |
1979年 | 8篇 |
1978年 | 9篇 |
1977年 | 5篇 |
1976年 | 6篇 |
1975年 | 7篇 |
1974年 | 5篇 |
排序方式: 共有2291条查询结果,搜索用时 31 毫秒
131.
Salvatore Massa Marisa Caruso Francesca Trovatelli Massimo Tosques 《World journal of microbiology & biotechnology》1998,14(5):727-730
In order to recover as many viable bacteria as possible from natural mineral water, in this study we have compared the counts obtained with the standard method (pour plate procedure with Plate Count Agar (PCA)) and counts with alternative test methods (PCA/spread plates, R2A medium/pour plates and R2A medium/spread plates). The results showed that counts with R2A medium/spread plates at 22°C and after a 7-day incubation period were more than 343% higher than those obtained with PCA/pour plate method. At 37°C and after a 3-day incubation period, the R2A pour plate technique gave counts about 368% greater than for the standard method. Moreover, while Pseudomonas, Comamonas and Acinetobacter species were isolated both from PCA and R2A medium, Flavobacterium spp. and Arthrobacter spp. were isolated only from R2A medium. For its higher productivity, R2A medium should be recommended for heterotrophic plate counts in natural mineral water. 相似文献
132.
Simonetta Pancaldi A. Bonora Rita Gualandri R. Gerdol R. Manservigi Maria Palmira Fasulo 《Plant biology (Stuttgart, Germany)》1998,111(4):261-272
Abstract: Laminae and petioles from mature winter leaves of Arum italicum were studied in order to obtain information on the sun—shade intra-tissue properties of chloroplasts. This inference was based on the: (1) micro- and submicroscopic characteristics of the chloroplasts, (2) cytochemical localizations of functional PS I and PS II, (3) pigment patterns and compositions, (4) immunolocalization of Rubisco, and (5) net photosynthesis. It was inferred that all the chloroplasts across the lamina had adaptations to intermediate shade conditions, without a sun-shade dimorphism between the palisade and the spongy tissues. In the petiole, where normally-structured chloroplasts were surprisingly present in the entire thickness of the organ, a structural and chemical dimorphism was found between the outer chlorenchyma and the inner aerenchyma where intermediate shade-type and extreme shade-type chloroplasts were present, respectively. However, some anomalies in the pigment composition were noted chiefly in the inner aerenchyma (low concentrations of β-carotene and lutein, absence of zeaxanthin, presence of unusual pigments, for instance lutein epoxide, lutein cis-isomer, and chlorophyllide a). The Rubisco immunolabelling in the outer chlorenchyma of the petiole was similar to that in the lamina, while it was very scant in the inner aerenchyma. Net photosynthesis in the petiole was about 75% of that recorded in the lamina. These data suggest that the petiole of the mature winter leaf of A. italicum closely co-operates with the lamina for enhancing light capture and utilization. 相似文献
133.
Marcella Zollino Rosetta Lecce Marina Murdolo Daniela Orteschi Giuseppe Marangi Angelo Selicorni Alina Midro Giovanni Sorge Giuseppe Zampino Luigi Memo Domenica Battaglia Michael Petersen Effie Pandelia Yolanda Gyftodimou Francesca Faravelli Romano Tenconi Livia Garavelli Laura Mazzanti Rita Fischetto Pietro Cavalli Salvatore Savasta Laura Rodriguez Giovanni Neri 《Human genetics》2008,123(3):319-319
134.
Wild Sicilian Rosemary: Phytochemical and Morphological Screening and Antioxidant Activity Evaluation of Extracts and Essential Oils
下载免费PDF全文
![点击此处可从《化学与生物多样性》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Edoardo M. Napoli Laura Siracusa Antonella Saija Antonio Speciale Domenico Trombetta Teresa Tuttolomondo Salvatore La Bella Mario Licata Giuseppe Virga Raffaele Leone Claudio Leto Laura Rubino Giuseppe Ruberto 《化学与生物多样性》2015,12(7):1075-1094
To identify the best biotypes, an extensive survey of Sicilian wild rosemary was carried out by collecting 57 samples from various sites, followed by taxonomic characterization from an agronomic perspective. All the biotypes collected were classified as Rosmarinus officinalis L. A cluster analysis based on the morphological characteristics of the plants allowed the division of the biotypes into seven main groups, although the characteristics examined were found to be highly similar and not area‐dependent. Moreover, all samples were analyzed for their phytochemical content, applying an extraction protocol to obtain the nonvolatile components and hydrodistillation to collect the essential oils for the volatile components. The extracts were characterized by LC‐UV‐DAD/ESI‐MS, and the essential oils by GC‐FID and GC/MS analyses. In the nonvolatile fractions, 18 components were identified, namely, 13 flavones, two organic acids, and three diterpenes. In the volatile fractions, a total of 82 components were found, with as predominant components α‐pinene and camphene among the monoterpene hydrocarbons and 1,8‐cineole, camphor, borneol, and verbenone among the oxygenated monoterpenes. Cluster analyses were carried out on both phytochemical profiles, allowing the separation of the rosemary samples into different chemical groups. Finally, the total phenol content and the antioxidant activity of the essential oils and extracts were determined with the Folin–Ciocalteu (FC) colorimetric assay, the UV radiation‐induced peroxidation in liposomal membranes (UV‐IP test), and the scavenging activity of the superoxide radical (O$\rm{{_{2}^{{^\cdot} -}}}$ ). The present study confirmed that the essential oils and organic extracts of the Sicilian rosemary samples analyzed showed a considerable antioxidant/free radical‐scavenging activity. 相似文献
135.
Biochemical and molecular characterization of Avena indolines and their role in kernel texture 总被引:1,自引:0,他引:1
136.
Antonio Pacilli Olga Lamacchia Andrea Fontana Massimiliano Copetti Mauro Cignarelli Vincenzo Trischitta Salvatore De Cosmo 《PloS one》2015,10(4)
Background
To investigate prospectively the relationship between target values of glycated hemoglobin, blood pressure and LDL-cholesterol, as considered in a combined fashion, and all-cause mortality in patients with type 2 diabetes mellitus.Methods
Two cohorts of patients with type 2 diabetes mellitus, the Gargano Mortality Study (n=810) and the Foggia Mortality Study (n=929), were investigated. A weighted target risk score was built as a weight linear combination of the recommended targets reached by each patient.Results
In the Gargano Mortality Study and in the Foggia Mortality Study (mean follow up=7.4 and 5.5 years, respectively), 161 (19.9%) and 220 (23.7%) patients died, with an age and sex adjusted annual incidence rate of 2.1 and 2.8 per 100 person-years, respectively. In both study samples the weighted target risk score tended to be linearly associated with all-cause mortality (HR for one point increment=1.30, 95% CI: 1.11-1.53, p=0.001, and HR=1.08, 95% CI: 0.95-1.24, p=0.243, respectively). When the two cohorts were pooled and analyzed together, a clear association between weighted target risk score and all-cause mortality was observed (HR for one point increment=1.17, 95% CI:1.05-1.30, p=0.004). This counterintuitive association was no longer observable in a model including age, sex, body mass index, smoking habit, estimated glomerular filtration rate, albuminuria and anti-diabetic, anti-hypertensive and anti-dyslipidemic treatment as covariates (HR for one point increment=0.99, 95% CI: 0.87-1.12, p=0.852).Conclusions
In a real life clinical set of patients with type 2 diabetes mellitus, the combination of recommended target values of established cardiovascular risk factors is not associated with all-cause mortality. 相似文献137.
Adriana Alagna Tomás Vega Fernández Giovanni D Anna Carlo Magliola Salvatore Mazzola Fabio Badalamenti 《PloS one》2015,10(4)
In the last decades the growing awareness of the ecological importance of seagrass meadows has prompted increasing efforts to protect existing beds and restore degraded habitats. An in-depth knowledge of factors acting as major drivers of propagule settlement and recruitment is required in order to understand patterns of seagrass colonization and recovery and to inform appropriate management and conservation strategies. In this work Posidonia oceanica seedlings were reared for five months in a land-based culture facility under simulated natural hydrodynamic conditions to identify suitable substrates for seedling anchorage. Two main substrate features were investigated: firmness (i.e., sand vs. rock) and complexity (i.e., size of interstitial spaces between rocks). Seedlings were successfully grown in culture tanks, obtaining overall seedling survival of 93%. Anchorage was strongly influenced by substrate firmness and took place only on rocks, where it was as high as 89%. Anchorage occurred through adhesion by sticky root hairs. The minimum force required to dislodge plantlets attached to rocky substrates reached 23.830 N (equivalent to 2.43 kg), which would potentially allow many plantlets to overcome winter storms in the field. The ability of rocky substrates to retain seedlings increased with their complexity. The interstitial spaces between rocks provided appropriate microsites for seedling settlement, as seeds were successfully retained, and a suitable substrate for anchorage was available. In conclusion P. oceanica juveniles showed a clear-cut preference for hard substrates over the sandy one, due to the root system adhesive properties. In particular, firm and complex substrates allowed for propagule early and strong anchorage, enhancing persistence and establishment probabilities. Seedling substrate preference documented here leads to expect a more successful sexual recruitment on hard bottoms compared with soft ones. This feature could have influenced P. oceanica patterns of colonization in past and present time. 相似文献
138.
Luca Salvatore De Santo Michele Torella Gianpaolo Romano Ciro Maiello Marianna Buonocore Ciro Bancone Alessandro Della Corte Nicola Galdieri Gianantonio Nappi Cristiano Amarelli 《PloS one》2015,10(5)
MethodsData on 362 consecutive recipients (mean age: 47.8±13.7, 20.2% female, 18.2% diabetics, 22.1% with previous cardiac operations, 27.6% hospitalized, 84.9±29.4 ml/min preoperative glomerular filtration rate) were analyzed using multivariable logistic regression modeling. Target outcomes were determinants of troponin release, early graft failure (EGF), acute kidney injury (AKI) and operative death.ResultsMean cTnI release measured 24 hours after transplant was 10.9±11.6 μg/L. Overall hospital mortality was 10.8%, EGF 10.5%, and AKI was 12.2%. cTnI release>10 μg/L proved an independent predictor of EGF (OR 2.2; 95% CI, 1.06–4.6) and AKI (OR 1.031; 95% CI, 1.001-1.064). EGF, in turn, proved a determinant of hospital mortality. Risk factors for cTnI>10 μg/L release were: status 2B (OR 0.35; 95% CI, 0.18-0.69, protective), duration of the ischemic period (OR 1.006; 95% CI, 1.001-1.011), previous cardiac operation (OR 2.9; 95% CI, 1.67-5.0), and left ventricular hypertrophy (OR 3.3; 95% CI, 1.9-5.6).ConclusionsMyocardial enzyme leakage clearly emerged as an epiphenomenon of more complicated clinical course. The complex interplay between surgical procedure features, graft characteristics and recipient end-organ function highlights cTnI release as a risk marker of graft failure and acute kidney injury. The search for optimal myocardial preservation is still an issue. 相似文献
139.
Elena Turola Salvatore Petta Ester Vanni Fabiola Milosa Luca Valenti Rosina Critelli Luca Miele Livia Maccio Vincenza Calvaruso Anna L. Fracanzani Marcello Bianchini Nazarena Raos Elisabetta Bugianesi Serena Mercorella Marisa Di Giovanni Antonio Craxì Silvia Fargion Antonio Grieco Calogero Cammà Franco Cotelli Erica Villa 《Disease models & mechanisms》2015,8(9):1037-1046
140.
Despite the increasing interest in twin studies and the stunning amount of research on face recognition, the ability of adult identical twins to discriminate their own faces from those of their co-twins has been scarcely investigated. One’s own face is the most distinctive feature of the bodily self, and people typically show a clear advantage in recognizing their own face even more than other very familiar identities. Given the very high level of resemblance of their faces, monozygotic twins represent a unique model for exploring self-face processing. Herein we examined the ability of monozygotic twins to distinguish their own face from the face of their co-twin and of a highly familiar individual. Results show that twins equally recognize their own face and their twin’s face. This lack of self-face advantage was negatively predicted by how much they felt physically similar to their co-twin and by their anxious or avoidant attachment style. We speculate that in monozygotic twins, the visual representation of the self-face overlaps with that of the co-twin. Thus, to distinguish the self from the co-twin, monozygotic twins have to rely much more than control participants on the multisensory integration processes upon which the sense of bodily self is based. Moreover, in keeping with the notion that attachment style influences perception of self and significant others, we propose that the observed self/co-twin confusion may depend upon insecure attachment. 相似文献