全文获取类型
收费全文 | 3661篇 |
免费 | 423篇 |
国内免费 | 1篇 |
出版年
2023年 | 19篇 |
2021年 | 86篇 |
2020年 | 65篇 |
2019年 | 57篇 |
2018年 | 59篇 |
2017年 | 61篇 |
2016年 | 97篇 |
2015年 | 174篇 |
2014年 | 185篇 |
2013年 | 212篇 |
2012年 | 258篇 |
2011年 | 224篇 |
2010年 | 146篇 |
2009年 | 138篇 |
2008年 | 181篇 |
2007年 | 163篇 |
2006年 | 160篇 |
2005年 | 155篇 |
2004年 | 131篇 |
2003年 | 144篇 |
2002年 | 137篇 |
2001年 | 67篇 |
2000年 | 72篇 |
1999年 | 50篇 |
1998年 | 41篇 |
1997年 | 30篇 |
1996年 | 28篇 |
1995年 | 27篇 |
1994年 | 18篇 |
1993年 | 24篇 |
1992年 | 64篇 |
1991年 | 56篇 |
1990年 | 34篇 |
1989年 | 53篇 |
1988年 | 35篇 |
1987年 | 39篇 |
1986年 | 37篇 |
1985年 | 31篇 |
1984年 | 42篇 |
1983年 | 29篇 |
1982年 | 24篇 |
1981年 | 25篇 |
1980年 | 30篇 |
1979年 | 22篇 |
1978年 | 26篇 |
1977年 | 18篇 |
1976年 | 24篇 |
1975年 | 26篇 |
1974年 | 25篇 |
1972年 | 16篇 |
排序方式: 共有4085条查询结果,搜索用时 31 毫秒
151.
Nathanael Lapidus Xavier de Lamballerie Nicolas Salez Michel Setbon Rosemary M. Delabre Pascal Ferrari Nanikaly Moyen Marie-Lise Gougeon Frédéric Vely Marianne Leruez-Ville Laurent Andreoletti Simon Cauchemez Pierre-Yves Bo?lle éric Vivier Laurent Abel Micha?l Schwarzinger Michèle Legeas Pierre Le Cann Antoine Flahault Fabrice Carrat 《PloS one》2013,8(4)
The CoPanFlu-France cohort of households was set up in 2009 to study the risk factors for infection by the pandemic influenza virus (H1N1pdm) in the French general population. The authors developed an integrative data-driven approach to identify individual, collective and environmental factors associated with the post-seasonal serological H1N1pdm geometric mean titer, and derived a nested case-control analysis to identify risk factors for infection during the first season. This analysis included 1377 subjects (601 households). The GMT for the general population was 47.1 (95% confidence interval (CI): 45.1, 49.2). According to a multivariable analysis, pandemic vaccination, seasonal vaccination in 2009, recent history of influenza-like illness, asthma, chronic obstructive pulmonary disease, social contacts at school and use of public transports by the local population were associated with a higher GMT, whereas history of smoking was associated with a lower GMT. Additionally, young age at inclusion and risk perception of exposure to the virus at work were identified as possible risk factors, whereas presence of an air humidifier in the living room was a possible protective factor. These findings will be interpreted in light of the longitudinal analyses of this ongoing cohort. 相似文献
152.
Piotr Bursztyka Dominique Saffray Céline Lafont-Lecuelle Antoine Brin Patrick Pageat 《PloS one》2013,8(11)
Evidence that terrestrial gastropods are able to detect chemical cues from their predators is obvious yet scarce, despite the scientific relevance of the topic to enhancing our knowledge in this area. This study examines the influence of cuticular extracts from predacious ground beetles (Carabus auratus, Carabus hispanus, Carabus nemoralis and Carabus coriaceus), and a neutral insect species (Musca domestica) on the shelter-seeking behavior of naive slugs (Deroceras reticulatum). Slugs, known to have a negative phototactic response, were exposed to light, prompting them to make a choice between either a shelter treated with a cuticular extract or a control shelter treated with pure ethyl alcohol. Their behavioral responses were recorded for one hour in order to determine their first shelter choice, their final position, and to compare the percentage of time spent in the control shelters with the time spent in the treated shelters.The test proved to be very effective: slugs spent most of the experiment in a shelter. They spent significantly more time in the control shelter than in the shelter treated with either C. nemoralis (Z = 2.43; p = 0.0151; Wilcoxon matched-pairs signed-ranks test) or C. coriaceus cuticular extracts (Z = 3.31; p<0.01; Wilcoxon matched-pairs signed-ranks test), with a seemingly stronger avoidance effect when presented with C. coriaceus extracts. The other cuticular extracts had no significant effect on any of the behavioral items measured. Although it cannot be entirely excluded that the differences observed, are partly due to the intrinsic properties of the vehicle employed to build the cuticular extracts, the results suggest that slugs can innately discriminate amongst different potential predators and adjust their behavioral response according to the relevance of the threat conveyed by their predator’s chemical cues. 相似文献
153.
154.
Jean-Emmanuel Bibault Sylvain Dewas Claire Vautravers-Dewas Antoine Hollebecque Hajer Jarraya Thomas Lacornerie Eric Lartigau Xavier Mirabel 《PloS one》2013,8(10)
Purpose
Stereotactic body radiation therapy (SBRT) for hepatocellular carcinoma (HCC) has been evaluated in several recent studies. The CyberKnife® is an SBRT system that allows for real-time tracking of the tumor. The purpose of this study was to evaluate the prognostic factors for local control and overall survival following this treatment.Patients and Methods
75 patients with 96 liver-confined HCC were treated with SBRT at the Oscar Lambret Comprehensive Cancer Center. Fiducials were implanted in the liver before treatment and were used as markers to track the lesion’s movement. Treatment response was scored according to RECIST v1.1. Local control and overall survival were calculated using the Kaplan and Meier method. A stepwise multivariate analysis (Cox regression) of prognostic factors was performed for local control and overall survival.Results
There were 67 patients with Child-Turcotte-Pugh (CTP) Class A and eight patients with CTP Class B. Treatment was administered in three sessions. A total dose of 40–45 Gy to the 80% isodose line was delivered. The median follow-up was 10 months (range, 3–49 months). The local control rate was 89.8% at 1 and 2 years. Overall survival was 78.5% and 50.4% at 1 and 2 years, respectively. Toxicity mainly consisted of grade 1 and grade 2 events. Higher alpha-fetoprotein (aFP) levels were associated with less favorable local control (HR=1.001; 95% CI [1.000, 1.002]; p=0.0063). A higher dose was associated with better local control (HR=0.866; 95% CI [0.753, 0.996]; p=0.0441). A Child-Pugh score higher than 5 was associated with worse overall survival (HR= 3.413; 95% CI [1.235, 9.435]; p=0.018).Conclusion
SBRT affords good local tumor control and higher overall survival rates than other historical controls (best supportive care or sorafenib). High aFP levels were associated with lesser local control, but a higher treatment dose improved local control. 相似文献155.
156.
Potential for Virus Endogenization in Humans through Testicular Germ Cell Infection: the Case of HIV
157.
Estelle Cateau Edouard Randriamalala Antoine Elsendoorn Jean-Philippe Giot Christophe Monegier du Sorbier Marie-Helene Rodier 《Mycopathologia》2013,176(5-6):423-427
Mucorales and Aspergillus are molds responsible for infections in immunocompromised patients. In this report, we describe a case of a rare extensively mixed cutaneous infection caused by Lichtheimia ramosa, Aspergillus fumigatus and Aspergillus terreus in a neutropenic patient suffering from an acute leukemia. The fatal outcome of this patient can be attributed to its hematologic malignancy, the extensive nature of the lesions and the resistance of the strains to antifungals. 相似文献
158.
Nicholas E. Geacintov Victor Ibanez Antoine G. Gagliano Stephen A. Jacobs Ronald G. Harvey 《Journal of biomolecular structure & dynamics》2013,31(6):1473-1484
Abstract The conformation of adducts derived from the reactions and covalent binding of the (+) and (-) enantiomers of 7β, 8α-dihydroxy-9α, 10α-epoxy-7,8,9,10-tetrahydrobenzo(a)pyrene (anti-BaPDE) with double-stranded calf thymus DNA in vitro were investigated utilizing the electric linear dichroism technique. The linear dichroism and absorption spectra of the covalent DNA complexes are interpreted in terms of a superposition of two types of binding sites. One of these conformations (site I) is a complex in which the plane of the pyrene residue is close to parallel (within 30°) to the planes of the DNA bases (quasi-intercalation), while the other (site II) is an external binding site; this latter type of adduct is attributed to the covalent binding of anti-BaPDE to the exocyclic amino group of deoxyguanine (N2-dG), while site I adducts are attributed to the 06-deoxyguanine and N6-deoxyadenine adducts identified in the product analysis of P. Brookes and M.R. Osborne (Carcinogenesis (1982) 3, 1223–1226). Site II adducts are dominant (~90% in the covalent complexes derived from the (+) enantiomer), but account for only 50±5% of the adducts in the case of the (—)-enantiomer. The orientation of site II complexes is different by 20±10° in the adducts derived from the binding of the (+) and the (—) enantiomers to DNA, the long axis of the pyrene chromophore being oriented more parallel to the axis of the DNA helix in the case of the (+) enantiomer. These findings support the proposals by Brookes and Osborne that the difference in spatial orientation of the N2-dG adducts of (-)-anti-BaPDE together with their lower abundance may account for the lower biological activity of the (—) enantiomer. The external site II adducts, rather than site I adducts, appear to be correlated with the biological activity of these comoounds. 相似文献
159.
Antoine Mantilleri 《法国昆虫学会纪事》2013,49(4):256-279
A small group of nine nominal species belonging to the genus Neacratus Alonso-Zarazaga, Lyal, Sforzi & Bartolozzi, 1999 is studied in detail from a morphological point of view. Lectotypes are designated for Brentus obtusus Lund, 1800 and Nemocephalus fulgidus Kleine, 1928. Three new synonymies are proposed: Nemocephalus brevicostatus Kleine, 1922 n. syn. for Brenthus obtusus Lund, 1800, Nemocephalus longiceps Perroud, 1853 n. syn. for Brenthus famulus Boheman, 1840, and Nemocephalus fulgidus Kleine, 1928 n. syn. for B. famulus Boheman, 1840. A new species, Neacratus pascali n. sp., is described from French Guiana. New country records are provided for Neacratus obtusus (Bolivia, Ecuador, French Guiana, Grenada, Peru, Trinidad and Tobago, Venezuela), N. puncticeps (Sharp, 1895) (Colombia, Ecuador, Venezuela), N. guatemalensis (Senna, 1893) (Belize, Colombia, El Salvador), N. deplanatus (Sharp, 1895) (Colombia, Costa Rica, French Guiana, Mexico, Panama, Venezuela) and N. famulus (Paraguay). A phylogenetic analysis carried out on this group shows it forms a monophyletic lineage included in a clade containing most of other species of Neacratus, of which it is the type species; it is therefore not justified to create a new generic name. The possible polyphyletism of the genus Neacratus as a whole and the development of an excessively long rostrum in some male Acratini are discussed. 相似文献
160.
This paper examines the roots of attitudes toward immigration among Australians of English-speaking background using the 1998, 2001, 2004, and 2007 Australian Election Studies. The paper demonstrates that attitudes toward immigration in Australia have their roots in multiple sources, some of them relating to the local context in which individuals reside, others in the socio-economic and financial situation experienced by individuals. Attitudes toward immigration in Australia are also related to attitudinal factors and historical legacies that manifest themselves in mistrust and suspicion toward Asian neighbours. Finally, the paper demonstrates that the presence of immigrants and ethnic minorities influences Australians' attitudes toward immigration but that this effect must be understood in conjunction with the educational context of the areas of residence. While in high education areas Australians tend to react positively to the presence of immigrants, in low education areas they tend to react negatively to the presence of immigrants. 相似文献