全文获取类型
收费全文 | 4110篇 |
免费 | 267篇 |
国内免费 | 2篇 |
出版年
2023年 | 17篇 |
2022年 | 48篇 |
2021年 | 100篇 |
2020年 | 59篇 |
2019年 | 71篇 |
2018年 | 106篇 |
2017年 | 93篇 |
2016年 | 135篇 |
2015年 | 218篇 |
2014年 | 198篇 |
2013年 | 289篇 |
2012年 | 341篇 |
2011年 | 367篇 |
2010年 | 219篇 |
2009年 | 182篇 |
2008年 | 249篇 |
2007年 | 247篇 |
2006年 | 208篇 |
2005年 | 208篇 |
2004年 | 174篇 |
2003年 | 170篇 |
2002年 | 146篇 |
2001年 | 40篇 |
2000年 | 35篇 |
1999年 | 29篇 |
1998年 | 34篇 |
1997年 | 31篇 |
1996年 | 24篇 |
1995年 | 25篇 |
1994年 | 20篇 |
1993年 | 30篇 |
1992年 | 20篇 |
1991年 | 9篇 |
1990年 | 20篇 |
1989年 | 14篇 |
1988年 | 9篇 |
1987年 | 13篇 |
1986年 | 11篇 |
1985年 | 13篇 |
1984年 | 16篇 |
1983年 | 11篇 |
1982年 | 18篇 |
1981年 | 7篇 |
1980年 | 12篇 |
1979年 | 9篇 |
1977年 | 8篇 |
1976年 | 7篇 |
1975年 | 6篇 |
1974年 | 16篇 |
1966年 | 6篇 |
排序方式: 共有4379条查询结果,搜索用时 46 毫秒
991.
Camila O. Arent Gislaine Z. Réus Helena M. Abelaira Karine F. Ribeiro Amanda V. Steckert Francielle Mina Felipe Dal-Pizzol João Quevedo 《Neurochemistry international》2012
A growing body of evidence has pointed to a relationship between oxidative stress and depression. Thus, the present study was aimed at evaluating the effects of the antioxidants n-acetylcysteine (NAC), deferoxamine (DFX) or their combination on sweet food consumption and oxidative stress parameters in rats submitted to 40 days of exposure to chronic mild stress (CMS). Our results showed that in stressed rats treated with saline, there was a decrease in sweet food intake and treatment with NAC or NAC in combination with DFX reversed this effect. Treatment with NAC and DFX decreased the oxidative damage, which include superoxide and TBARS production in submitochondrial particles, and also thiobarbituric acid reactive substances (TBARS) levels and carbonyl proteins in the prefrontal cortex, amygdala and hippocampus. Treatment with NAC and DFX also increased the activity of the antioxidant enzymes, superoxide dismutase and catalase in the same brain areas. Even so, a combined treatment with NAC and DFX produced a stronger increase of antioxidant activities in the prefrontal cortex, amygdala and hippocampus. The results described here indicate that co-administration may induce a more pronounced antidepressant activity than each treatment alone. In conclusion, these results suggests that treatment with NAC or DFX alone or in combination on oxidative stress parameters could have positive effects against neuronal damage caused by oxidative stress in major depressive disorders. 相似文献
992.
du Puy L Beqqali A van Tol HT Monshouwer-Kloots J Passier R Haagsman HP Roelen BA 《The International journal of developmental biology》2012,56(4):301-309
SARCOSIN, also named Krp1, has been identified as a protein exclusively expressed in striated muscle tissue. Here we report on the role of SARCOSIN in skeletal muscle development and differentiation. We demonstrate, by means of whole-mount in situ hybridization, that Sarcosin mRNA is expressed in the myotome part of the mature somites in mouse embryos from embryonic day 9.5 onwards. Sarcosin is not expressed in the developing heart at these embryonic stages, and in adult tissues the mRNA expression levels are five times lower in the heart than in skeletal muscle. SARCOSIN protein partially co-localizes with the M-band protein myomesin and between and below laterally fusing myofibrils in adult skeletal muscle tissue. RNA interference mediated knock-down of SARCOSIN in the C2C12 myoblast cell line appeared to be stimulatory in the early phase of differentiation, but inhibitory at a later phase of differentiation. 相似文献
993.
Cerovska N Hoffmeisterova H Moravec T Plchova H Folwarczna J Synkova H Ryslava H Ludvikova V Smahel M 《Journal of biosciences》2012,37(1):125-133
Transient expression of foreign genes based on plant viral vectors is a suitable system for the production of relevant immunogens
that can be used for the development of a new generation of vaccines against a variety of infectious diseases. In the present
study the epitope derived from HPV-16 L2 minor capsid protein (amino acids 108–120) was expressed from Potato virus X (PVX)-based vector pGR106 as N- or C-terminal fusion with the PVX coat protein (PVX CP) in transgenic Nicotiana benthamiana plants. The fusion protein L2108-120-PVX CP was successfully expressed in plants at a level of 170 mg/kg of fresh leaf tissue. The C-terminal fusion protein PVX
CP- L2108-120 was expressed using mutated vector sequence to avoid homologous recombination at a level of 8 mg/kg of fresh leaf tissue.
Immunogenicity of L2108-120-PVX CP virus-like particles was tested after immunization of mice by subcutaneous injection or tattoo administration. In
animal sera the antibodies against the PVX CP and the L2108-120 epitope were found after both methods of vaccine delivery. 相似文献
994.
Wiebke-Strohm B Pasquali G Margis-Pinheiro M Bencke M Bücker-Neto L Becker-Ritt AB Martinelli AH Rechenmacher C Polacco JC Stolf R Marcelino FC Abdelnoor RV Homrich MS Del Ponte EM Carlini CR De Carvalho MC Bodanese-Zanettini MH 《Plant molecular biology》2012,79(1-2):75-87
The soybean ubiquitous urease (encoded by GmEu4) is responsible for recycling metabolically derived urea. Additional biological roles have been demonstrated for plant ureases, notably in toxicity to other organisms. However, urease enzymatic activity is not related to its toxicity. The role of GmEu4 in soybean susceptibility to fungi was investigated in this study. A differential expression pattern of GmEu4 was observed in susceptible and resistant genotypes of soybeans over the course of a Phakopsora pachyrhizi infection, especially 24 h after infection. Twenty-nine adult, transgenic soybean plants, representing six independently transformed lines, were obtained. Although the initial aim of this study was to overexpress GmEu4, the transgenic plants exhibited GmEu4 co-suppression and decreased ureolytic activity. The growth of Rhizoctonia solani, Phomopsis sp., and Penicillium herguei in media containing a crude protein extract from either transgenic or non-transgenic leaves was evaluated. The fungal growth was higher in the protein extracts from transgenic urease-deprived plants than in extracts from non-transgenic controls. When infected by P. pachyrhizi uredospores, detached leaves of urease-deprived plants developed a significantly higher number of lesions, pustules and erupted pustules than leaves of non-transgenic plants containing normal levels of the enzyme. The results of the present work show that the soybean plants were more susceptible to fungi in the absence of urease. It was not possible to overexpress active GmEu4. For future work, overexpression of urease fungitoxic peptides could be attempted as an alternative approach. 相似文献
995.
Hectare-scale demonstration of high rate algal ponds for enhanced wastewater treatment and biofuel production 总被引:1,自引:0,他引:1
High rate algal ponds (HRAPs) are shallow, paddlewheel-mixed open raceway ponds that are an efficient and cost-effective upgrade for the conventional wastewater treatment ponds used by communities and farms the world over. HRAPs provide improved natural disinfection and nutrient removal and can be further enhanced by carbon dioxide (CO2) addition to promote algal growth which is often carbon limited. This paper discusses the construction and operation of a 5-ha demonstration HRAP system treating primary settled wastewater at the Christchurch wastewater treatment plant, New Zealand. The system consisted of four 1.25-ha HRAPs that were constructed from an existing conventional pond. Algae were harvested from the HRAP effluent in specially designed settlers, which concentrated the algal/bacterial biomass to 1–2% organic solids for conversion to bio-crude oil following dewatering. Performance data from the first 15?months of HRAP operation (without CO2 addition) are presented. The four demonstration HRAPs had reasonable replication of both treatment performance and algal/bacterial productivity with similar annual average wastewater treatment efficiency (~50% removal of BOD5, ~87% removal of fBOD5, ~65% removal of ammoniacal-N, ~19% removal of dissolved reactive phosphorus and ~2 log removal of Escherichia coli), algal species composition and algal/bacterial biomass production (~8?g?m?2?day ?1 volatile suspended solids). These results were in good agreement with the results for pilot-scale HRAP without CO2 addition in New Zealand. This study provides further indication of the potential for energy efficient and effective wastewater treatment using HRAP, while biofuel conversion of the harvested algal bacterial biomass could provide a valuable niche distributed energy source for local communities. 相似文献
996.
Noemi Cerovska Tomas Moravec Helena Plchova Hana Hoffmeisterova Petr Dedic 《Journal of Phytopathology》2012,160(5):251-254
The genes encoding the coat protein (CP) and triple gene block protein 1 (TGBp1) of Potato virus M (PVM) were cloned into expression vector pET‐45b(+) (N‐terminal 6xHis tag) and expressed in E. coli Rosetta gami‐2(DE3). The purified recombinant antigens were used for raising polyclonal antibodies. The antibodies against recombinant CP were successfully used in Western blot analysis, plate‐trapped ELISA and DAS‐ELISA as a coating for PVM detection in infected potato leaf samples. The antibodies against recombinant non‐structural protein detected the TGBp1 only in Western blot analysis. This is the first report of the production of polyclonal antibodies against recombinant coat protein and TGBp1 of PVM and their use for detecting the virus. 相似文献
997.
998.
Hélder Antônio Rebelo Pontes Helena Borges Paiva Brunno Santos de Freitas Silva Felipe Paiva Fonseca Fernanda Bragança Monteiro da Silva Flávia Sirotheau Corrêa Pontes Décio dos Santos Pinto Jr 《Gerodontology》2012,29(1):70-74
doi: 10.1111/j.1741‐2358.2010.00371.x Oral candidiasis mimicking an oral squamous cell carcinoma: report of a case Oral candidiasis is a significant problem in immune‐compromised patients. The most common forms of mucosal candidiasis are oropharyngeal, oesophageal and vaginal, and more than 90% of HIV positive persons will manifest at least one episode of oropharyngeal candidiasis. Local and systemic factors such as uninterrupted daily use of a prosthesis by patients, smoking habit, as well as high glucose intake may contribute to the development of the lesion. The aim of this article is to report an uncommon case of oral candidiasis presenting an aggressive clinical behaviour in a 64‐year‐old male patient, with a significant smoking habit and a medical history of non‐controlled diabetes. The lesion affected the hard and soft palate of the right side, revealing erythematous and ulcerated areas, elevated borders and central portions resembling necrosis, mimicking the clinical features of oral squamous cell carcinoma. However, the correct diagnosis of oral candidiasis was obtained after histopathological and cytological examinations and the patient was easily treated with traditional antifungal drugs and correction of his glucose levels. 相似文献
999.
1000.