全文获取类型
收费全文 | 3538篇 |
免费 | 180篇 |
国内免费 | 7篇 |
专业分类
3725篇 |
出版年
2024年 | 12篇 |
2023年 | 35篇 |
2022年 | 158篇 |
2021年 | 214篇 |
2020年 | 91篇 |
2019年 | 111篇 |
2018年 | 138篇 |
2017年 | 90篇 |
2016年 | 160篇 |
2015年 | 202篇 |
2014年 | 218篇 |
2013年 | 260篇 |
2012年 | 263篇 |
2011年 | 258篇 |
2010年 | 130篇 |
2009年 | 123篇 |
2008年 | 164篇 |
2007年 | 158篇 |
2006年 | 139篇 |
2005年 | 117篇 |
2004年 | 111篇 |
2003年 | 108篇 |
2002年 | 95篇 |
2001年 | 33篇 |
2000年 | 15篇 |
1999年 | 29篇 |
1998年 | 28篇 |
1997年 | 19篇 |
1996年 | 8篇 |
1995年 | 20篇 |
1994年 | 15篇 |
1993年 | 16篇 |
1992年 | 11篇 |
1991年 | 12篇 |
1990年 | 8篇 |
1989年 | 15篇 |
1987年 | 10篇 |
1986年 | 8篇 |
1985年 | 13篇 |
1984年 | 5篇 |
1983年 | 9篇 |
1982年 | 10篇 |
1981年 | 11篇 |
1980年 | 13篇 |
1979年 | 6篇 |
1978年 | 9篇 |
1977年 | 7篇 |
1975年 | 6篇 |
1974年 | 5篇 |
1966年 | 5篇 |
排序方式: 共有3725条查询结果,搜索用时 15 毫秒
131.
Biological Trace Element Research - Instrumental neutron activation analysis (INAA) has been used to determine the concentration of some toxic chemical elements in a variety of aromatic plants... 相似文献
132.
Mohammed Arshad Hossain Khaled Al-Abdul-Elah Salim El-Dakour 《Zeitschrift fur angewandte Ichthyologie》2019,35(6):1197-1208
A 6‐month long study was conducted to improve the nutritional quality of the cultured sobaity bream, Sparidentex hasta by feeding them finisher feeds containing high docosahexaenoic acid (DHA) at the last two months of the grow‐out stage so that the muscle DHA level be increased at par to the wild. A grow‐out feed used from the beginning until the end of the trial was considered as the control (Diet 1). Experimental diets 2 and 3 were formulated to contain 9.0% DHA (e.g. 1.68 g DHA/100 g feed) and 10.5% DHA (2.20 g DHA/100 g feed), by incorporating high DHA tuna oil into a sea bream grow‐out diet. For comparison, a commercial finisher feed (Diet 4) from Skretting, Italy was also used. The results of this study demonstrated that fish fed DHA enriched finisher diets resulted in significantly (p < .05) better growth, feed utilization and higher muscle eicosapentaenoic acid (EPA) and DHA content compared to those fed grow‐out diet. The muscle DHA and EPA of fish fed finisher diets were also higher than those of the whole year average DHA and EPA content of wild sobaity. An organoleptic evaluation showed no significant (p > .05) differences between sensory attributes of muscle from cultured and wild sea bream. The results of the study demonstrated that feeding finisher feed enriched with DHA at the later part of the grow‐out operation, the n‐3 PUFA levels of cultured sobaity can cost‐effectively be increased at par to the wild. 相似文献
133.
Pradeep Kumar Yadalam Santhiya Rengaraj Maryam H. Mugri Mohammed Sayed Amit Porwal Nasser Mesfer Alahmari Khaled M. Alzahrani Ali Robaian Hosam Ali Baeshen Shankargouda Patil 《Saudi Journal of Biological Sciences》2022,29(1):622-629
ObjectivesPeri-implantitis is a destructive inflammatory process that affects the soft and hard tissues around dental implants. porphyromonas gingivalis, an anaerobic gram-negative bacterium, appears to be the main culprit. Since there is no efficient and specific vaccine to treat peri-implantitis, the goal of our research has been to develop a multi-epitope vaccination utilizing an immunoinformatics approach that targeted P. gingivalis type I fim A.Materials and methodsP. gingivalis peptides 6JKZ and 6KMF are suitable for vaccine development. B- and T-cell epitopes from 6KMF and 6JKZ were detected and evaluated based on critical factors to produce a multi-epitope vaccine construct. It was assessed based on allergenicity, antigenicity, stability. The vaccine's dual major histocompatibility complex (MHC-I and MHC-II) binding epitopes allowed it to reach a larger population. P. gingivalis fimbriae induce immune subversion through TLR -CXCR4 receptor complex pathway. The ClusPro 2.0 server was used to do the molecular docking using TLR2 - CXCR4 and vaccine epitopes as receptor and ligand respectively.ResultsThe designed vaccine was non-allergenic and had a high antigenicity, solubility, and stability. The 3D structure of the vaccine revealed strong interaction with CXCR4(TLR2) using molecular docking. The vaccine-CXCR4 interface was more consistent, possibly because the vaccination has a higher affinity for the CXCR4-TLR2 complex.ConclusionThis study details the vaccine's distinct and sustained interaction with the CXCR4(TLR2) immunological receptor and its consistent and effective utterance in the bacterial system. As a result, our vaccine formulation will evoke a significant memory response and induce an adaptive immune response against P. gingivalis. 相似文献
134.
Abdallah E. Abdallah Reda R. Mabrouk Maged Mohammed Saleh Al Ward Sally I. Eissa Eslam B. Elkaeed Ahmed B. M. Mehany Mariam A. Abo-Saif Ola A. El-Feky Mohamed S. Alesawy Mohamed Ayman El-Zahabi 《Journal of enzyme inhibition and medicinal chemistry》2022,37(1):573
Based on quinazoline, quinoxaline, and nitrobenzene scaffolds and on pharmacophoric features of VEGFR-2 inhibitors, 17 novel compounds were designed and synthesised. VEGFR-2 IC50 values ranged from 60.00 to 123.85 nM for the new derivatives compared to 54.00 nM for sorafenib. Compounds 15a, 15b, and 15d showed IC50 from 17.39 to 47.10 µM against human cancer cell lines; hepatocellular carcinoma (HepG2), prostate cancer (PC3), and breast cancer (MCF-7). Meanwhile, the first in terms of VEGFR-2 inhibition was compound 15d which came second with regard to antitumor assay with IC50 = 24.10, 40.90, and 33.40 µM against aforementioned cell lines, respectively. Furthermore, Compound 15d increased apoptosis rate of HepG2 from 1.20 to 12.46% as it significantly increased levels of Caspase-3, BAX, and P53 from 49.6274, 40.62, and 42.84 to 561.427, 395.04, and 415.027 pg/mL, respectively. Moreover, 15d showed IC50 of 253 and 381 nM against HER2 and FGFR, respectively. 相似文献
135.
Nicole C. Thunes Rachel A. Conrad Haitham H. Mohammed Yongtao Zhu Paul Barbier Jason P. Evenhuis David Perez-Pascual Jean-Marc Ghigo Ryan S. Lipscomb John R. Schneider Nan Li Devon H. Erbes Clayton Birkett Benjamin R. LaFrentz Timothy J. Welch Mark J. McBride 《Applied and environmental microbiology》2022,88(3)
136.
Ahmed A. Mohammed Ahmed M. Ahmed Ahmed M. El-Otify 《International Review of Hydrobiology》1989,74(5):549-578
Seasonal, local and monthly vertical variations in chlorophyll a concentration and in qualitative and quantitative counts in Aswan High Dam Lake (AHDL) phytoplankton were followed from March 1982 to February 1984. The chlorophyll a values correlated more or less with the total phytoplankton counts. Total algal counts exhibited considerable local variations in the different seasons and tended to decrease in the most southern part of AHDL, especially during the flood period. The temporal course of algal development showed an almost inverse trend to that of dissolved nitrate-nitrogen. The possibility of nitrogen limitation of algal growth was verified. Diatoms and blue-green algae alternated in the dominance of the phytoplankton community. The genera Cyclotella and Anabaenopsis respectively were the most predominant genera among the diatoms and blue-greens and consequently in the phytoplankton community. 相似文献
137.
138.
139.
Mohammed Nuruzzaman Tatsuo Kanno Rika Amada Yoshiki Habu Ichiro Kasajima Toshiki Ishikawa Maki Kawai-Yamada Hirofumi Uchimiya 《PloS one》2014,9(9)
The genomic nucleotide sequences of japonica rice (Sasanishiki and Nipponbare) contained about 2.7-kb unique region at the point of 0.4-kb upstream of the OsPsbS1 gene. In this study, we found that japonica rice with a few exceptions possessing such DNA sequences [denoted to OsMULE-japonica specific sequence (JSS)] is distinct by the presence of Mutator-like-element (MULE). Such sequence was absent in most of indica cultivars and Oryza glaberrima. In OsMULE-JSS1, we noted the presence of possible target site duplication (TSD; CTTTTCCAG) and about 80-bp terminal inverted repeat (TIR) near TSD. We also found the enhancement ofOsPsbS1 mRNA accumulation by intensified light, which was not associated with the DNA methylation status in OsMULE/JSS. In addition, O. rufipogon, possible ancestor of modern rice cultivars was found to compose PsbS gene of either japonica (minor) or indica (major) type. Transient gene expression assay showed that the japonica type promoter elevated a reporter gene activity than indica type. 相似文献
140.
Mohammed I. Al-Daej Mohamed M. El-Malky Muhammad N. Sattar Adel A. Rezk Muhammad N. Naqqash Jameel M. Al-Khayri 《Phyton》2022,91(9):1905-1922
Rice stem borer (Chilo agamemnon Bles.) is a primary insect pest of rice and is a major limiting factor to rice
production. Breeding for insect-resistant crop varieties has been an economic way of integrated pest management
(IPM) as it offers a viable and ecologically acceptable approach. This study was aimed to evaluate rice genotypes
for their resistance against rice stem borer. Seven parental genotypes with twenty one F1 crosses were evaluated
for genotypic variation in field experiments. Analysis of variance revealed significant differences for the studied
traits in almost all crosses and parents. In addition, the mean squares of parents versus their crosses were signifi-
cant for stem borer resistance and other associated traits. Moreover, both general combining ability (GCA) and
specific combining ability (SCA) variances were highly significant for all characters studied in the F1 generation.
Based on GCA, 4 genotypes (Sakha101, Gz6903-3-4-2-1, Gz9577-4-1-1 and Hassawi) exhibited highly significant
negative values for stem borer resistance (–0.53, –1.06, –0.18 and –0.49, respectively) indicating they are the best
combiners for stem borer resistance. Based on SCA analysis, nine cross combinations showed highly significant
negative effects for stem borer resistance. Similarly, the cross Giza178 Hassawi was the best combination with
significantly highest value for early maturity. In addition, seven crosses showed highly significant negative
SCA for plant height trait. On the other hand, for panicle length, number of primary branches/panicle, panicle
weight and 1000-grain weight, seven, four, eight and six crosses showed highly significant positive SCA, respectively. The result further revealed that the non-additive dominance genetic variance was higher than the additive
variance for all evaluated traits indicating that non-additive genetic variances have a role in their inheritance. The
broad-sense heritability estimates were high for all the studied traits. The stem borer resistance was significantly
correlated with panicle weight and 1000-grain weight, which also showed a highly significant correlation with
grain yield/plant. Thus these traits can be effectively employed in a breeding program to confer resistance against
stem borer infestation in rice. It was further supported by biplot analysis, which clustered these potentially important traits into two quadrants showing their importance in any future breeding program to control stem borer
infestation. This study has contributed valuable information for evaluation of genetic diversity in the local rice
germplasm and its utilization in futuristic rice genetic improvement programs. 相似文献