全文获取类型
收费全文 | 640篇 |
免费 | 36篇 |
国内免费 | 1篇 |
出版年
2022年 | 4篇 |
2021年 | 11篇 |
2020年 | 5篇 |
2019年 | 10篇 |
2018年 | 19篇 |
2017年 | 13篇 |
2016年 | 25篇 |
2015年 | 26篇 |
2014年 | 31篇 |
2013年 | 34篇 |
2012年 | 45篇 |
2011年 | 38篇 |
2010年 | 21篇 |
2009年 | 17篇 |
2008年 | 39篇 |
2007年 | 27篇 |
2006年 | 24篇 |
2005年 | 17篇 |
2004年 | 15篇 |
2003年 | 13篇 |
2002年 | 14篇 |
2001年 | 18篇 |
2000年 | 15篇 |
1999年 | 16篇 |
1998年 | 6篇 |
1997年 | 4篇 |
1996年 | 5篇 |
1995年 | 5篇 |
1994年 | 5篇 |
1993年 | 5篇 |
1992年 | 11篇 |
1991年 | 11篇 |
1990年 | 11篇 |
1989年 | 12篇 |
1988年 | 9篇 |
1987年 | 6篇 |
1986年 | 7篇 |
1985年 | 8篇 |
1983年 | 5篇 |
1982年 | 4篇 |
1981年 | 3篇 |
1978年 | 5篇 |
1977年 | 3篇 |
1976年 | 5篇 |
1975年 | 7篇 |
1974年 | 9篇 |
1973年 | 11篇 |
1972年 | 5篇 |
1971年 | 4篇 |
1969年 | 3篇 |
排序方式: 共有677条查询结果,搜索用时 78 毫秒
91.
92.
Naeela Qureshi Pakeerathan Kandiah Mesfin Kebede Gessese Vallence Nsabiyera Vanessa Wells Prashanth Babu Debbie Wong Matthew Hayden Harbans Bariana Urmil Bansal 《Molecular breeding : new strategies in plant improvement》2018,38(8):97
Stem rust of wheat, caused by Puccinia graminis f. sp. tritici (Pgt), is a threat to global food security due to its ability to cause total crop failures. The Pgt race TTKSK (Ug99) and its derivatives detected in East Africa carry virulence for many resistance genes present in modern cultivars. However, stem rust resistance gene Sr26 remains effective to all races of Pgt worldwide. Sr26 is carried on the Agropyron elongatum (syn. Thinopyrum ponticum) segment 6Ae#1L translocated to chromosome 6AL of wheat. In this study, a recombinant inbred line (RIL) population derived from a cross between the landrace Aus27969 and Avocet S, which carries Sr26, was used to develop co-dominant kompetitive allele-specific polymerase chain reaction (KASP) markers that co-segregate with Sr26. Four KASP markers (sunKASP_216, sunKASP_218, sunKASP_224 and sunKASP_225) were also shown to co-segregate with Sr26 in four additional RIL populations. When tested on Australian cultivars and breeding lines, these markers amplified alleles alternate to that linked with Sr26 in all cultivars known to lack this gene and Sr26-linked alleles in cultivars and genotypes known to carry Sr26. Genotypes WA-1 and WA-1/3*Yitpi carrying the shortest Sr26 translocation segment were positive only for markers sunKASP_224 and sunKASP_225. Our results suggest the four KASP markers are located on the original translocation and sunKASP_224 and sunKASP_225 are located on the shortened version. Therefore, sunKASP_224 and sunKASP_225 can be used for marker-assisted pyramiding of Sr26 with other stem rust resistance genes to achieve durable resistance in wheat. 相似文献
93.
Gousia Mehraj Anzar A. Khuroo Salman Qureshi Insha Muzafar Cynthia Ross Friedman Irfan Rashid 《Biodiversity and Conservation》2018,27(5):1055-1072
In an age of Anthropocene, the urban landscapes are recognised as the ‘hotspots’ of human-mediated alien species introductions. As the cities provide an ideal natural experimental system to investigate the patterns of alien plant diversity in urban landscapes, the present study aimed to unravel the taxonomic, biogeographic and ecological patterns of alien flora of Srinagar—one of the largest urban centres in the Himalayan biodiversity hotspot. The alien flora of Srinagar comprises 325 species, constituting ca.35% of total flora of the city. Out of the 325 alien species documented, 157 species (43%) were recorded to be under cultivation, while 168 species (57%) were growing in the wild (i.e., outside cultivation); those growing in the wild, in turn, comprised 110 cultivation escapes and 58 accidentally introduced plant species. Biogeographically, two-third of the alien plant diversity reported from Srinagar is native to Asia-Temperate. This indicates that climatic similarity between Asia-Temperate and Kashmir Himalayas facilitate in flourishing similar floristic diversity. The study highlights a relatively higher proportion of herbaceous growth form in the aliens growing in the wild (80%) than those under cultivation (43%). Similarly, 82% of the alien species under cultivation had a perennial life span, but those growing in the wild were dominated by annuals (44%). Currently, 45 species are growing as casuals and 124 species are naturalised (including 105 naturalised non-invasive and 19 naturalised invasive). Along the continuum of casual-naturalised-invasive categories, the contribution of cultivation escapes and accidently introduced aliens contrastingly shows decreasing and increasing trends respectively. Interestingly, the results revealed that the human practice of stopping cultivation of alien escapes increased rapidly as we move along the continuum. Thus, the present study has investigated the patterns of alien plant diversity in the urban landscape of Srinagar, and the results obtained offer scientific insights toward better scientific understanding and management of plant invasions in this Himalayan city, with wider policy implications for neighbouring urbanised landscapes in the Himalayas and other mountainous regions across the world. 相似文献
94.
Ali Zohaib Muhammad Saqib Muhammad Ammar Athar Jing Chen Awais-ur-Rahman Sial Saeed Khan Zeeshan Taj Halima Sadia Usman Tahir Muhammad Haleem Tayyab Muhammad Asif Qureshi Muhammad Khalid Mansoor Muhammad Ahsan Naeem Bing-Jie Hu Bilal Ahmed Khan Ikram Din Ujjan Bei Li Wei Zhang Yun Luo Yan Zhu Cecilia Waruhiu Iahtasham Khan Xing-Lou Yang Muhammad Sohail Sajid Victor Max Corman Bing Yan Zheng-Li Shi 《中国病毒学》2018,33(5):410-417
Middle East Respiratory Syndrome Coronavirus (MERS-CoV) is a zoonotic pathogen capable of causing severe respiratory disease in humans. Although dromedary camels are considered as a major reservoir host, the MERS-CoV infection dynamics in camels are not fully understood. Through surveillance in Pakistan, nasal (n = 776) and serum (n = 1050)samples were collected from camels between November 2015 and February 2018. Samples were collected from animal markets, free-roaming herds and abattoirs. An in-house ELISA was developed to detect IgG against MERS-CoV. A total of 794 camels were found seropositive for MERS-CoV. Prevalence increased with the age and the highest seroprevalence was recorded in camels aged [ 10 years (81.37%) followed by those aged 3.1–10 years (78.65%) and B 3 years (58.19%).Higher prevalence was observed in female (78.13%) as compared to male (70.70%). Of the camel nasal swabs, 22 were found to be positive by RT-qPCR though with high Ct values. Moreover, 2,409 human serum samples were also collected from four provinces of Pakistan during 2016–2017. Among the sampled population, 840 humans were camel herders.Although we found a high rate of MERS-CoV antibody positive dromedaries (75.62%) in Pakistan, no neutralizing antibodies were detected in humans with and without contact to camels. 相似文献
95.
Rohan R. Singh Jodie A. Kemp James F. Kollmorgen Javed A. Qureshi Geoffrey B. Fincher 《Plant Cell, Tissue and Organ Culture》1997,49(2):121-127
Fertile plants were regenerated from both cell suspension and protoplast-derived cultures of the two-row barley, Hordeum vulgare
L. cv. Schooner. Embryogenic calluses, derived from immature embryos, were used to establish suspension cultures. More than
100 plants, with variable seed set, have been regenerated from six embryogenic cell suspension cultures. Protoplasts isolated
from three suspension cultures divided and when the resultant embryogenic proto-calluses were transferred to regeneration
medium both green and albino shoots were produced. The green shoots were transferred to growth regulator-free medium and plantlets
that developed strong root systems were potted in soil and grown to maturity in the glasshouse. Root tip analysis of plants
regenerated from cell suspension cultures revealed the expected 2N = 14 complement of chromosomes. However, chromosomal analysis
of protoplast-derived plants showed numerical variation among a proportion of the regenerants.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
96.
Quantification of ketoprofen enantiomers in human plasma based on solid-phase extraction and enantioselective column chromatography 总被引:1,自引:0,他引:1
Julie Boisvert Gilles Caill Iain J. McGilveray Saeed A. Qureshi 《Journal of chromatography. B, Analytical technologies in the biomedical and life sciences》1997,690(1-2):189-193
An HPLC method for the quantification of ketoprofen enantiomers in human plasma is described. Following extraction with a disposable C18 solid-phase extraction column, separation of ketoprofen enantiomers and I.S. (3,4-dimethoxy benzoic acid) was achieved using a chiral column [Chirex 3005; (R)-1-naphthylglycine 3,5-dinitrobenzoic acid] with the mobile phase, 0.02 M ammonium acetate in methanol, set at a flow-rate of 1.2 ml/min. Baseline separation of ketoprofen enantiomers and I.S., free from interferences, was achieved in less than 20 min. The calibration curves (n = 14) were linear over the concentration range of 0.16 to 5.00 μg/ml per enantiomer [mean r2 of 0.999 for both enantiomers, root mean square error were 0.015 for R(−) and 0.013 for S(+)]. The inter-day coefficient of variation for duplicate analysis of spiked samples was less than 7% and the accuracy was more than 93% over the concentration range of 0.2 to 4.0 μg/ml for individual enantiomer using 1 ml of plasma sample. This method has been applied to a pharmacokinetic study from healthy human volunteers following the administration of a ketoprofen extended release product (200 mg). This method is simple, fast and should find wide application in monitoring pharmacokinetic studies of ketoprofen. 相似文献
97.
G.Dastgir Qureshi Philip S. Guzelian R.Marcus Vennart Herbert J. Evans 《Biochimica et Biophysica Acta (BBA)/Molecular Cell Research》1985,844(3):288-295
Because of the inherent difficulties of experimentation in intact animals, we used primary monolayer cultures of non-proliferating adult rat hepatocytes to study the effects of fibrinogen degradation products on fibrinogen biosynthesis. The freshly isolated hepatocytes obtained by collagenase perfusion of the liver in situ were cultured in a chemically defined serum-free medium. The rate of fibrinogen synthesis in control cultures was cells per 24 h. Additions of 20, 60 or 100 μg of homologous stage I fibrinogen degradation products had no effect on fibrinogen synthesis. In contrast, addition of the same amounts of homologous or heterologous (human) stage III fibrinogen degradation products resulted in a concentration-dependent increase in fibrinogen biosynthesis without affecting the rate of synthesis of albumin. When purified stage III fibrinogen degradation products D and E (human) were tested in 10, 30 or 50 μg/3 ml medium only fragment E showed a significant increase in fibrinogen biosynthesis (1.9-, 2.8- and 5.6-fold, respectively, over the control cultures). The presence of excess fibrinogen had no effect. These results suggest that fibrinogen fragment E may be a specific stimulator of fibrinogen biosynthesis which may play an important role in maintaining normal levels of plasma fibrinogen. 相似文献
98.
Pulse-labeled Saint Louis encephalitis viral ribonucleic acid (RNA) is found in the cytoplasm of infected cells associated with a membranous structure which sediments with an average value of 250S. The integrity of the complex is destroyed by detergents and ribonuclease; however, it is stable in ethylenediaminetetraacetic acid (EDTA) which differentiates this structure from cellular polyribosomes. With cultures in which cellular RNA was highly labeled prior to infection, ribosomal RNA could not be demonstrated in the complex isolated from EDTA-sucrose gradients. Single-stranded 43S and the 26S and 20S forms of viral RNA were found in the complex. Viral RNA polymerase activity in sucrose-gradient fractions sedimented in the same region as the fractions which contained the pulse-labeled viral RNA. The polymerase incorporated (3)H-guanosine triphosphate into acid-precipitable material in the absence of added template. It was also found that the replication complex contains viral-specific proteins. 相似文献
99.
100.
The effect of nitrogen on the movement of tracers down the stolon of Saxifraga sarmentosa,with some observations on the influence of light 总被引:1,自引:0,他引:1
Summary The movement of applied 137Cs and of naturally-assimilated 14C down the long stolon of Saxifraga is strongly inhibited by confining a length of 10 to 30 cm of the stolon in an atmosphere of nitrogen. The inhibition is reversible, normal transport being restored after less then 4 h when the stolon is returned to air from 5 h in nitrogen. Callose formation does not seem to be involved. There is evidence that local darkness has a similar adverse effect on phloem transport.These findings are considered antagonistic to the pressure-flow hypothesis, but favourable to the active mass-flow theories.This work formed part of that submitted for the degree of Ph.D. of the University of London. 相似文献