全文获取类型
收费全文 | 1504篇 |
免费 | 93篇 |
国内免费 | 2篇 |
专业分类
1599篇 |
出版年
2023年 | 15篇 |
2022年 | 36篇 |
2021年 | 62篇 |
2020年 | 65篇 |
2019年 | 117篇 |
2018年 | 117篇 |
2017年 | 58篇 |
2016年 | 69篇 |
2015年 | 71篇 |
2014年 | 106篇 |
2013年 | 141篇 |
2012年 | 128篇 |
2011年 | 125篇 |
2010年 | 74篇 |
2009年 | 64篇 |
2008年 | 56篇 |
2007年 | 61篇 |
2006年 | 38篇 |
2005年 | 25篇 |
2004年 | 34篇 |
2003年 | 23篇 |
2002年 | 19篇 |
2001年 | 5篇 |
2000年 | 5篇 |
1999年 | 8篇 |
1998年 | 4篇 |
1997年 | 3篇 |
1996年 | 6篇 |
1995年 | 2篇 |
1994年 | 3篇 |
1993年 | 3篇 |
1992年 | 3篇 |
1991年 | 4篇 |
1990年 | 3篇 |
1989年 | 4篇 |
1988年 | 2篇 |
1987年 | 2篇 |
1986年 | 2篇 |
1985年 | 3篇 |
1984年 | 3篇 |
1983年 | 5篇 |
1982年 | 3篇 |
1980年 | 2篇 |
1979年 | 2篇 |
1978年 | 3篇 |
1975年 | 2篇 |
1974年 | 3篇 |
1972年 | 2篇 |
1968年 | 3篇 |
1945年 | 1篇 |
排序方式: 共有1599条查询结果,搜索用时 0 毫秒
101.
Li Z Mehdi S Patel I Kawooya J Judkins M Zhang W Diener K Lozada A Dunnington D 《Journal of biomolecular screening》2000,5(1):31-38
We have developed a novel assay for measuring the activity of an enzyme that transfers multiple adenine-containing groups to an acceptor protein. The assay is based on fluorescence polarization (FP) technology in a 1536-well plate format. In the assay, a long wavelength fluorescence tracer, Texas Red (Rhodamine), was covalently conjugated to adenine of the donor substrate through a C(6) spacer arm. As a result of the transfer of the adenine-containing moieties to the acceptor protein substrate, the rotational correlation time of the Texas Red conjugate increased, hence increasing the degree of fluorescence polarization. The pharmacological profile and kinetics of the enzyme measured according to the FP method were consistent with those determined previously by conventional analysis. We have successfully executed a 250,000-compound high throughput screening program based on the FP assay method. The quality and validity of the assay were verified by a variety of statistical analyses. 相似文献
102.
Identification of the New Pathogen (Stemphylium lycopersici) Causing Leaf Spot on Pepino (Solanum muricatum) 下载免费PDF全文
Abbas Nasehi Jugah Kadir Mehdi Nasr‐Esfahani Farnaz Abed‐Ashtiani Elham Golkhandan Sadegh Ashkani 《Journal of Phytopathology》2016,164(6):421-426
Pepino (Solanum muricatum var. pepino) plants were found affected by an extensive leaf spot caused by plant pathogenic fungi during a survey in the Cameron highlands, Pahang state, Malaysia. Symptomatic leaf samples were collected from infected pepino plants and cultivated on PDA medium, and the pathogen was isolated and purified; then, consequently, all isolates were identified as Stemphylium lycopersici on the basis of their cultural and morphological characteristics and combined sequences of the internal transcribed spacer (ITS) and glyceraldehyde‐3‐phosphate dehydrogenase (gpd) regions. A pathogenicity assay on detached leaves further confirmed that S. lycopersici causes leaf spot disease. To the best of our knowledge, this is the first report of S. lycopersici causing leaf spot on pepino in Malaysia and worldwide. 相似文献
103.
Mojtaba Alimolaei Mehdi Golchin Jalil Abshenas Majid Ezatkhah Mehrdad Shamsaddini Bafti 《Probiotics and antimicrobial proteins》2018,10(2):251-257
The alpha-toxin is one of the virulence factors of Clostridium perfringens for gas gangrene in humans and animals or necrotic enteritis in poultry. The C-terminal domain of this toxin ( cpa 247-370 ) was synthesized and cloned into pT1NX vector to construct the pT1NX-alpha plasmid. This surface-expressing plasmid was electroporated into Lactobacillus casei ATCC 393, generating the recombinant L. casei strain expressing alpha-toxoid (LC-α strain). Expression of this modified alpha-toxoid was confirmed by SDS-PAGE, immunoblotting, and direct immunofluorescence microscopy. BALB/c mice, immunized orally by the recombinant LC-α strain, elicited mucosal and significantly humoral immune responses (p < 0.05) and developed a protection against 900 MLD/mL of the standard alpha-toxin. This study showed that this recombinant LC-α strain could be a promising vaccine candidate against gas gangrene and necrotic enteritis. 相似文献
104.
Toghyani M Toghyani M Shivazad M Gheisari A Bahadoran R 《Biological trace element research》2012,146(2):171-180
This study was conducted to determine the effects of dietary supplementation with Cr nicotinate and Cr chloride and their
optimum inclusion rate on performance, carcass traits, meat oxidative stability, serum metabolites, hematological parameters,
and liver chromium concentration in heat-stressed broilers. A total number of 420, 1-day-old male broiler chicks were randomly
assigned to seven treatments with four replicates of 15 chicks. The dietary treatments consisted of the basal diet supplemented
with 0 (control), 500, 1,000, and 1,500 μg/kg Cr in the form of Cr nicotinate and Cr chloride. Chicks were raised for 6 weeks
in heat stress condition (33 ± 2°C). Supplements of organic and inorganic Cr particularly at 1,500 μg/kg incorporation increased
feed consumption (P < 0.05) and body mass gain of broilers (P < 0.01). Cr supplementation increased carcass yield and decreased abdominal fat (P < 0.01). Supplementation of 1,500 μg/kg Cr nicotinate (P < 0.05) enhanced liver Cr concentration. Storage time increased lipid oxidation of meat (P < 0.01). Cr decreased lipid oxidation of breast and thigh muscles over 2 (P < 0.01) or 6 (P < 0.05) days of storage time. Birds fed 1,500 μg/kg Cr nicotinate, had lower concentration of serum glucose and triglyceride
at 21 days (P < 0.05). Hematological parameters tested at 21 and 42 days, were not influenced. The results suggested that dietary Cr supplementation
regardless of its source have a positive effect on productive, and carcass traits, also enhances oxidative stability of refrigerated
meat in broilers reared under heat stress conditions. 相似文献
105.
Pirkhezranian Zana Tanhaeian Abbas Mirzaii Mehdi Sekhavati Mohammad Hadi 《International journal of peptide research and therapeutics》2020,26(3):1503-1512
International Journal of Peptide Research and Therapeutics - Cancer remains one of the leading causes of death worldwide. Introduction of natural compounds with anticancer properties can be an... 相似文献
106.
The aim of the study was a cross-cultural comparison of personality traits between individuals from two very different cultures and refugees who resettled several years before from one to the other. Four hundred forty four Swedish individuals of the normal population; and 100 Iranian refugees in Sweden, and a group of 335 individuals from Tehran, capital of Iran, were investigated by means of the Temperament and Character Inventory, a questionnaire to assess temperament and character Iranians are those that are most frequently correctly classified followed by the Swedish based on temperament scores by means of a Discriminance analyses. Iranian refugees in Sweden were classified to about 50 per cent as Swedish and to slightly more then one-third as Iranians. Especially concerning character, 4 per cent only could be correctly classified as refugees. The results give some perspective on the adaptation process and personality changes in refugees several years after resettlement in another country with a complete different culture. 相似文献
107.
Variation in Essential Oil Yield and Composition of Dorema aucheri Boiss., an Endemic Medicinal Plant Collected from Wild Populations in Natural Habitats 下载免费PDF全文
In the present research, variability in essential oil (EO) composition of five Dorema aucheri populations collected from natural habitats in different regions of Iran, were investigated. The EO content of populations varied from 0.28 to 0.68%. According to gas chromatography/mass spectrometry analysis, β‐caryophyllene (7.17 – 35.73%), thymol (23.45 – 29.64%), β‐gurjunene (2.58 – 5.89%), carvacrol (1.32 – 2.67%) and cuparene (1.97 – 2.98%) were the major components. Hierarchical cluster, principal component and canonical correspondence analyses classified the studied populations into three groups based on major EO components. The environmental parameters of the collected sites were also evaluated. According to the results, it might be suggested that sandy soils with high mean annual precipitation were major environmental factors influencing the amount of β‐caryophyllene, while thymol, cuparene and caryophyllen oxide increased in silty and clay soils. Finally, the population collected in high altitudes and clay soils had higher amount of β‐gurjunene. 相似文献
108.
Lauriane Sollelis Mehdi Ghorbal Cameron Ross MacPherson Rafael Miyazawa Martins Nada Kuk Lucien Crobu Patrick Bastien Artur Scherf Jose‐Juan Lopez‐Rubio Yvon Sterkers 《Cellular microbiology》2015,17(10):1405-1412
Protozoan pathogens that cause leishmaniasis in humans are relatively refractory to genetic manipulation. In this work, we implemented the CRISPR‐Cas9 system in Leishmania parasites and demonstrated its efficient use for genome editing. The Cas9 endonuclease was expressed under the control of the Dihydrofolate Reductase‐Thymidylate Synthase (DHFR‐TS) promoter and the single guide RNA was produced under the control of the U6snRNA promoter and terminator. As a proof of concept, we chose to knockout a tandemly repeated gene family, the paraflagellar rod‐2 locus. We were able to obtain null mutants in a single round of transfection. In addition, we confirmed the absence of off‐target editions by whole genome sequencing of two independent clones. Our work demonstrates that CRISPR‐Cas9‐mediated gene knockout represents a major improvement in comparison with existing methods. Beyond gene knockout, this genome editing tool opens avenues for a multitude of functional studies to speed up research on leishmaniasis. 相似文献
109.
Ivan Light Georges Sabagh Mehdi Bozorgmehr Claudia Der‐Martirosian 《Ethnic and racial studies》2013,36(4):581-597
Internal ethnicity refers to ethnic subgroups within an immigrant group. An ‘ethnic economy’ includes the self‐employed and their co‐ethnic workers. Although most research treats the boundaries of ‘ethnic economy’ and its variant, the ‘ethnic enclave economy’, as though they were coterminous with those of national‐origin immigrant groups, this assumption is unreliable. Ethnic boundaries need not coincide with those of nationality origin when internal ethnicity exists. To test this hypothesis, we utilize survey data collected from a sample of Iranians in Los Angeles. Because this national‐origin immigrant group contains four ethno‐religious subgroups (Armenians, Bahais, Jews and Muslims), the Iranians in Los Angeles operated four distinctive ethnic economies, not one. Each ethno‐religious subgroup had its own ethnic economy, and these separate economies were only weakly tied to an encompassing Iranian ethnic economy. 相似文献
110.
Shima Sadat Beheshti Rooy Ghasem Hosseini Salekdeh Mehdi Ghabooli Mansour Gholami Rouhollah Karimi 《Acta Physiologiae Plantarum》2017,39(12):264
In this study the cold tolerance potential of three Vitis vinifera cultivars including ‘Red Sultana’, ‘White Sultana,’ and ‘Flame Seedless’ was evaluated under greenhouse condition. After 15 leaves stage in average, the grapevine plants were subjected to cold stress regimes (4, 0 and ? 4 °C) and compared with control plants (24 °C). A clear increase in leaf electrolyte leakage (EL), thiobarbituric acid reactive substances (TBARS), and H2O2 concentrations was observed with decreasing temperature from 4 to ? 4 °C in all grapevine cultivars. Chilled plants showed marked increases in their abscisic acid (ABA), soluble sugars, and proline contents in compared to control vines. Upon exposure to cold stress, the EL, TBARS, H2O2, and relative water content of ‘Red Sultana’ were found to be lower compared to ‘White Sultana’ and ‘Flame Seedless’. Under 0 °C condition, ‘Red Sultana’ had the highest superoxide dismutase, guaiacol peroxidase and catalase activities, which was approximately twofold higher than those of all other cultivars. Soluble sugars such as glucose, fructose, and sucrose increased from 4 to ? 4 °C. These increments were higher in ‘Red Sultana’ compared to other cultivars which was concomitant with higher accumulation of endogenous ABA concentration in this cultivar. Higher accumulation of ABA and soluble sugars in ‘Red Sultana’ confirmed the key roles of these compounds in cold tolerance which could be applied as a cold tolerance marker for early selection of grapevine cultivars with the aim to establish vineyards in cold winter regions. 相似文献