全文获取类型
收费全文 | 1077篇 |
免费 | 20篇 |
专业分类
1097篇 |
出版年
2024年 | 6篇 |
2023年 | 15篇 |
2022年 | 51篇 |
2021年 | 67篇 |
2020年 | 37篇 |
2019年 | 40篇 |
2018年 | 49篇 |
2017年 | 40篇 |
2016年 | 48篇 |
2015年 | 48篇 |
2014年 | 68篇 |
2013年 | 101篇 |
2012年 | 68篇 |
2011年 | 58篇 |
2010年 | 42篇 |
2009年 | 51篇 |
2008年 | 34篇 |
2007年 | 38篇 |
2006年 | 31篇 |
2005年 | 23篇 |
2004年 | 17篇 |
2003年 | 22篇 |
2002年 | 16篇 |
2001年 | 15篇 |
2000年 | 16篇 |
1999年 | 5篇 |
1998年 | 12篇 |
1997年 | 5篇 |
1996年 | 4篇 |
1995年 | 5篇 |
1994年 | 4篇 |
1993年 | 3篇 |
1992年 | 3篇 |
1991年 | 2篇 |
1990年 | 2篇 |
1989年 | 2篇 |
1988年 | 7篇 |
1987年 | 2篇 |
1985年 | 3篇 |
1984年 | 7篇 |
1982年 | 3篇 |
1980年 | 2篇 |
1979年 | 2篇 |
1977年 | 2篇 |
1976年 | 2篇 |
1968年 | 3篇 |
1967年 | 2篇 |
1962年 | 3篇 |
1956年 | 1篇 |
1940年 | 1篇 |
排序方式: 共有1097条查询结果,搜索用时 0 毫秒
1.
A new organic solvent tolerant protease from <Emphasis Type="Italic">Bacillus pumilus</Emphasis> 115b 总被引:3,自引:0,他引:3
Rahman RN Mahamad S Salleh AB Basri M 《Journal of industrial microbiology & biotechnology》2007,34(7):509-517
Five out of the nine benzene–toulene–ethylbenzene-xylene (BTEX) tolerant bacteria that demonstrated high protease activity
on skim milk agar were isolated. Among them, isolate 115b identified as Bacillus pumilus exhibited the highest protease production. The protease produced was stable in 25% (v/v) benzene and toluene and it was activated
1.7 and 2.5- fold by n-dodecane and n-tetradecane, respectively. The gene encoding the organic solvent tolerant protease was cloned and its nucleotide sequence
determined. Sequence analysis revealed an open reading frame (ORF) of 1,149 bp that encoded a polypeptide of 383 amino acid
residues. The polypeptide composed of 29 residues of signal peptide, a propeptide of 79 residues and a mature protein of 275
amino acids with a calculated molecular mass of 27,846 Da. This is the only report available to date on organic solvent tolerant
protease from B. pumilus. 相似文献
2.
Summary Comparative study of the different methods of extraction and estimation of the algal nitrogenous constituents mainly proteins of an Egyptian strain ofChlorella ellipsoidea had been carried out. This study also involves the assay of the different fractions of the soluble nitrogenous compounds. 相似文献
3.
Esmat M. Hegazi Maria A. Konstantopoulou Annette Herz Wedad E. Khafagi Essam Agamy Sania Showiel Atwa Atwa Gehan M. Abd El‐Aziz Safaa M. Abdel‐Rahman 《Insect Science》2011,18(5):565-574
Abstract Prays oleae Bern, (OM) and Palpita unionalis Hüb., (JM) are two of the most important pests in olive groves in Egypt. A 3‐year monitoring study using sex pheromone traps in semi‐arid and arid olive groves was performed. In the semi‐arid grove, flight pattern of the OM was the same as in other Mediterranean countries, but in dates concordating plant phenology. The moth completes three generations annually: the first flight is in March to April, the second is in May to June and the third occurs in August to October. In the arid olive grove, an interesting flight pattern was observed. First flight was always very close or overlapped with the second one with no male catches during August to October. However, eggs were present most of the season, indicating unusually high female presence and oviposition activity of the OM during the absence of males in the traps. Generally, moth densities were significantly lower in low fruiting years than in higher ones and were also lower in the arid olive grove than in the semi‐arid one. In contrast, JM males were present all season, exhibiting six to seven and three to four overlapping flight peaks in arid and semi‐arid olive groves, respectively. Moth densities were significantly higher in the arid olive grove than those in the semi‐arid one. This study shows that trapping location and fruit bearing year are characteristics that strongly affect the grove‐specific information needed to estimate correctly adult emergence and thus the timing of control measures. 相似文献
4.
OBJECTIVE: To report a patient with an unusual presentation of autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy (APECED) and severe keratopathy. CASE HISTORY: An Egyptian male sustained an injury to the left eye at 13 years of age and was found to have corneal damage which was attributed to the injury. Subsequently, however, he continued to have sore eyes with photophobia. A year later he became weak with pigmentation and episodes of collapse, and investigation showed that he had Addison's disease together with mucocutaneous candidiasis. At 15 years of age he developed carpo-pedal spasm and was found to have hypoparathyroidism with intracranial calcification. At 20 years of age the ophthalmic diagnosis was revised to keratopathy by which time the patient had corneal opacity and problems with visual acuity, especially in the right eye. Investigation at 22 years of age showed that he was homozygous for an R139X mutation in the gene encoding the AIRE protein, a mutation which to date has only been found in Sardinian patients. CONCLUSIONS: Keratopathy can be an early and severe manifestation of APECED, requiring expert ophthalmic care. Its presence should prompt a search for other components of APECED, some of which are life-threatening. 相似文献
5.
Release Mechanisms Behind Polysaccharides-Based Famotidine Controlled Release Matrix Tablets 总被引:1,自引:0,他引:1
Enas M. Elmowafy Gehanne A. S. Awad Samar Mansour Abd El-Hamid A. El-Shamy 《AAPS PharmSciTech》2008,9(4):1230-1239
Polysaccharides, which have been explored to possess gelling properties and a wide margin of safety, were used to formulate
single-unit floating matrix tablets by a direct compression technique. This work has the aim to allow continuous slow release
of famotidine above its site of absorption. The floating approach was achieved by the use of the low density polypropylene
foam powder. Polysaccharides (κ-carrageenan, gellan gum, xyloglucan, and pectin) and blends of polysaccharides (κ-carrageenan
and gellan gum) and cellulose ethers (hydroxypropylmethyl cellulose, hydroxypropylcellulose, sodium carboxymethyl cellulose)
were tried to modulate the release characteristics. The prepared floating tablets were evaluated for their floating behavior,
matrix integrity, swelling studies, in vitro drug release studies, and kinetic analysis of the release data. The differential scanning calorimetry and Fourier transform
infrared spectroscopy studies revealed that changing the polymer matrix system by formulation of polymers blends resulted
in formation of molecular interactions which may have implications on drug release characteristics. This was obvious from
the retardation in drug release and change in its mechanistics. 相似文献
6.
7.
8.
9.
Abdul Hafiz Ab Majid Hamady Dieng Siti Salbiah Ellias Faezah Syukriah Sabtu Abd Hafis Abd Rahim Tomomitsu Satho 《Journal of Asia》2018,21(1):46-51
Odor sensation is a sensory modality of considerable significance in the foraging behavior and interactional organization of ants. In the food bait technology, smell is the basis of attraction, which, in turn, is the line of bait use and a key parameter for judging efficacy. Yet, the currently available baits possess low attractiveness to many ant pests. Hence, strategies to produce ant bait with increased attractiveness are needed. Despite evidence that coffee has a diverse aroma complex that affects the behavior of honey bees and ants, its attraction to house-invading ants has yet to be investigated. In a series of Y-tube olfactometer bioassays, we examined the behavioral responses of Tapinoma indicum (TI), Monomorium pharaonis (MP) and Solenopsis geminata (SG) to various coffee-induced odor stimuli, comprised of extracts from Arabica, Robusta and Liberica. All coffee extracts showed an influence on the behavior of TI, MP and SG workers, with Arabica showed the most significant influence to the tested ants. The workers of TI, MP and SG were more attracted to the odor of 0.01% Arabica extract (ONE), in comparison with 0.05% Arabica extract (TWO) or 0.10% Arabica extract (THREE). Arabica extract mixed with sugar (S) elicited a significant attraction from workers of all three species in a balanced competition with either unsweetened Arabica extract or water. These results indicated that coffee, particularly Arabica, was attractive to the foragers of TI, MP and SG, thus, the use of coffee as a novel stimulus agent seems plausible in ant bait development. 相似文献
10.
Mohamed S. Ayyat Adham A. Al-Sagheer Khaled M. Abd El-Latif Bakry A. Khalil 《Biological trace element research》2018,185(1):162-169
Lead (Pb) is a ubiquitous and toxic heavy metal and it can damage the immune system in humans and animals. Many researchers have reported that Selenium (Se) could possess various pharmacological effects in mammals. However, few studies have been carried out to investigate the protective role of Se in birds, especially in chickens. In this study, we investigated the protective effects of Se against Pb-induced inflammatory responses and the expression of heat shock proteins (HSPs) in peripheral blood neutrophils. One hundred eighty Hy-Line brown chickens were randomly divided into the control group (Con group), Se supplementation group (+Se group), Pb supplementation group (+Pb group), and the Se and Pb compound group (Se+Pb group). On the 90th day of the experiment, the peripheral blood was collected to extract neutrophils, and then, the levels of HSPs and cytokines were examined. The results showed that, after Pb treatment, the levels of IL-(1β, 1R, 4, 8, 10, and 12β), TGF-β4, and HSP (27, 40, 60, 70, and 90) mRNA were significantly increased and levels of IL-2 and IFN-γ mRNA were decreased compared with those in the control group. Compared with the control group, the protein levels of HSP60 and HSP70 were also increased in the Pb treatment group. Co-administration of Se (1 mg/kg/day) and Pb resulted in a reversal of the Pb-induced cytokine changes in neutrophils accompanied by a significant decrease in HSPs. Our study demonstrated that Pb could decrease the immune function via changing the expression of cytokines and HSPs in chicken neutrophils, but Se could relieve the toxic effect induced by Pb. 相似文献