全文获取类型
收费全文 | 370篇 |
免费 | 39篇 |
专业分类
409篇 |
出版年
2024年 | 4篇 |
2023年 | 6篇 |
2022年 | 17篇 |
2021年 | 28篇 |
2020年 | 9篇 |
2019年 | 13篇 |
2018年 | 15篇 |
2017年 | 15篇 |
2016年 | 19篇 |
2015年 | 27篇 |
2014年 | 27篇 |
2013年 | 24篇 |
2012年 | 39篇 |
2011年 | 22篇 |
2010年 | 13篇 |
2009年 | 18篇 |
2008年 | 15篇 |
2007年 | 14篇 |
2006年 | 19篇 |
2005年 | 13篇 |
2004年 | 4篇 |
2003年 | 5篇 |
2002年 | 6篇 |
2001年 | 3篇 |
2000年 | 2篇 |
1999年 | 5篇 |
1998年 | 3篇 |
1996年 | 1篇 |
1995年 | 1篇 |
1993年 | 1篇 |
1991年 | 2篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1988年 | 2篇 |
1987年 | 3篇 |
1986年 | 1篇 |
1982年 | 1篇 |
1977年 | 3篇 |
1976年 | 3篇 |
1975年 | 2篇 |
1973年 | 1篇 |
1972年 | 1篇 |
排序方式: 共有409条查询结果,搜索用时 0 毫秒
1.
S. R. Saif 《Plant and Soil》1987,97(1):25-35
Summary Growth and mineral uptake of twenty-four tropical forage legumes and grasses were compared under glasshouse conditions in a sterile low P oxisol, one part inoculated and the other not inoculated with mycorrhizal fungi. Shoot and root dry weights and total uptake of P, N, K, Ca, and Mg of all the test plants were significantly increased by mycorrhizal inoculation. Mycorrhizal inoculation, with few exceptions, decreased the root/shoot ratio. Non-mycorrhizal plants contained always lower quantities of mineral elements than mycorrhizal plants. Plant species showed differences in percentage mycorrhizal root length and there was no correlation between percentage mycorrhizal infection and plant growth parameters. A great variation in dependence on mycorrhiza was observed among forage species. Total uptake of all elements by non-mycorrhizal legumes and uptake of P, N and K by non-mycorrhizal grasses correlated inversely with mycorrhizal dependency. Mycorrhizal plants of all species used significantly greater quantities of soil P than the nonmycorrhizal plants. Utilization of soil P by non-mycorrhizal plants was correlated inversely with mycorrhizal dependency. 相似文献
2.
The synthesis and secretion of chondroitin sulphate proteoglycan (CSPG) was examined in human muscle cultures during myogenesis prior to myoblast fusion and following myotube formation. Results from this study demonstrate that the major CSPG secreted into the medium had a Kav of 0.15 on Sephacryl 500 (exclusion limit of 10(7) Da) and contained predominantly unsulphated residues in mononucleated cell cultures but these became increasingly sulphated in postfusion cultures. Fibroblasts synthesised small amounts of a smaller molecular weight CSPG indicating that the Kav 0.15 proteoglycan is solely synthesised by cells of the myogenic lineage. These findings illustrate that sulphation of CSPG is developmentally regulated during myogenesis of human muscle cells grown under differentiating conditions. 相似文献
3.
Sheikh Abdul Hamid N. Zen Hee B. Tein Ong B. Halifah Yasin M. Saari Nazamid Bakar Fatimah Abu 《World journal of microbiology & biotechnology》2003,19(9):961-968
Seven lipase-producing thermophilic bacteria (ST 1, ST 4, ST 6, ST 7, ST 8, ST 9 and ST 10) were isolated from the Setapak hot spring in Malaysia. The crude extracellular lipases recovered by ultrafiltration of cell-free culture supernatant were reacted in an olive oil mixture and their lipolytic activities were compared. Identification of the bacteria was carried out using the Biolog system and biochemical tests. Strain ST 7 that exhibited the highest lipolytic activity of 4.58 U/ml was identified as belonging to the Bacillus genus. Strain ST 6 with an activity of 3.51 U/ml, was identified as Ralstonia paucula. The lipolytic activities of strains ST 1, ST 4, ST 8, ST 9 and ST 10 were 2.39, 1.84, 2.38, 1.80 and 2.62 U/ml respectively. Strains ST 1, ST 4, and ST 10 were identified as Ralstonia paucula while strains ST 8 and ST 9 were Bacillus spp. Strains ST 7 and ST 9 were tentatively identified as Bacillus thermoglucosidasius, Bacillus stearothermophilus or Bacillus coagulans, whereas strain ST 8 was tentatively identified as Bacillus subtilis. 相似文献
4.
Tianyuan Li Saif Ullah He Liang Izhar Ali Quan Zhao Anas Iqbal Shanqing Wei Tariq Shah Yuqiong Luo Ligeng Jiang 《Phyton》2021,90(1):223-243
Readily available chemical fertilizers have resulted in a decline in the
use of organic manure (e.g., green manures), a traditionally sustainable source
of nutrients. Based on this, we applied urea at the rate of 270 kg ha−1 with and
without green manure in order to assess nitrogen (N) productivity in a double rice
cropping system in 2017. In particular, treatment combinations were as follows:
winter fallow rice-rice (WF-R-R), milk vetch rice-rice (MV-R-R), oil-seed rape
rice-rice (R-R-R) and potato crop rice-rice (P-R-R). Results revealed that green
manure significantly (p ≤ 0.05) improved the soil chemical properties and net soil
organic carbon content increased by an average 117.47%, total nitrogen (N) by
28.41%, available N by 26.64%, total phosphorus (P) by 37.77%, available P
by 20.48% and available potassium (K) by 33.10% than WF-R-R, however pH
was reduced by 3.30% across the seasons. Similarly, net dry matter accumulation
rate enhanced in green manure applied treatments and ranked in order: P-R-R >
R-R-R > MV-R-R > WF-R-R. Furthermore, the total leaf dry matter transport
(t ha−1
) for the P-R-R in both seasons was significantly higher by an average
11.2%, 7.2% and 36 % than MV-R-R, R-R-R, and WF-R-R, respectively. In addition, net total nitrogen accumulation (kg ha−1
) was found higher in green manure
applied plots compared to the control. Yield and yield attributed traits were
observed maximum in green manure applied plots, with treatments ranking as follows: P-R-R > R-R-R > MV-R-R > WF-R-R. Thus, results obtained highlight
ability of green manure to sustainably improve soil quality and rice yield. 相似文献
5.
6.
7.
Tipu Muhammad Imran Ashraf Muhammad Yasin Sarwar Nadeem Akhtar Muhammad Shaheen Muhammad Rashid Ali Sajjad Damalas Christos A. 《Journal of Plant Growth Regulation》2021,40(2):774-786
Journal of Plant Growth Regulation - Nickel (Ni) element is strongly phytotoxic at high concentrations for several plants, but due to its dual behavior and complicated chemistry, it has received... 相似文献
8.
Laçine Aksoy Erdi Kolay Yasin Ağılönü Zeyneb Aslan Mustafa Kargıoğlu 《Saudi Journal of Biological Sciences》2013,20(3):235-239
Thermopsis turcica, endemic to Turkey, is in danger of extinction. Studies on this species are very few due to the fact that it was only discovered in 1983 and grows in a small circumscribed area in Turkey. In this study, free radical scavenging activity, total phenolic content, total oxidant status (TOS), and total antioxidant status (TAS) of methanol (TTM) and acetone (TTA) extracts of T. turcica were measured spectroscopically. Free radical scavenging activity was determined according to the elimination of DPPH radicals and total phenol content was determined by the Folin–Ciocalteu reaction. Total oxidant status (TOS) and total antioxidant status (TAS) were measured with commercially available kits. Methanol and acetone extracts of T. turcica were found to have a specific radical scavenging effect. This effect was found to be related to the total phenolic content of the extracts. Since the TTA had a higher phenolic content than the methanol extract, it had a stronger radical scavenging effect. In addition, the total antioxidant capacity of the methanol extract was observed to be higher than that of its acetone counterpart. As a result, due to its antioxidative properties, T. turcica is thought to be a natural source of antioxidants. 相似文献
9.
Medine Gulluce Mehmet Karadayi Burak Alaylar Taha Yasin Koc Selma Sezen 《Geomicrobiology journal》2020,37(7):618-622
AbstractMagnesite is an important raw material used in various industrial applications, especially the production of high-temperature resistant materials. Due to its high reactant nature, magnesite ore is not found in pure form and it contains a great variety of pollutants such as calcium compounds, which restrict its use when exceeding 1% of the ore. Thus, the development of efficient strategies for the removal of pollutants remains a crucial step for magnesite utilization. In this regard, our present work was conducted to isolate and identify active fungal strains that remove calcium pollutants without changing the main magnesium content of the ore. For this aim, magnesite ore samples were collected from two quarries (Turanoca?? and Ortaocak) of KÜMA? Magnesite Inc. and fungal isolation studies were done by using the ore’s flora. Active isolates were chosen according to their CaCO3 and MgCO3 dissolving capabilities and identified by using conventional light microscopy and molecular characterization techniques. 71 fungal isolates were obtained from the isolation step and 14 of them were chosen as active isolates that solve calcium compounds while not affecting the magnesium component. The data of the microscopic examination and 18S rDNA gene sequence analysis showed that 14 active strains with magnesite enrichment potential grouped in Aspergillus alliaceus (3), Aspergillus flavus (2), Aspergillus leporis (1), Aspergillus nomius (1), Fusarium tricinctum (2), Penicillium chrysogenum (1) and Penicillium sp. (4). 相似文献
10.
Feng Zhu Anil Kalra Tal Saif Zaihan Yang King H. Yang Albert I. King 《Computer methods in biomechanics and biomedical engineering》2016,19(10):1053-1059
Traumatic brain injury due to primary blast loading has become a signature injury in recent military conflicts and terrorist activities. Extensive experimental and computational investigations have been conducted to study the interrelationships between intracranial pressure response and intrinsic or ‘input’ parameters such as the head geometry and loading conditions. However, these relationships are very complicated and are usually implicit and ‘hidden’ in a large amount of simulation/test data. In this study, a data mining method is proposed to explore such underlying information from the numerical simulation results. The heads of different species are described as a highly simplified two-part (skull and brain) finite element model with varying geometric parameters. The parameters considered include peak incident pressure, skull thickness, brain radius and snout length. Their interrelationship and coupling effect are discovered by developing a decision tree based on the large simulation data-set. The results show that the proposed data-driven method is superior to the conventional linear regression method and is comparable to the nonlinear regression method. Considering its capability of exploring implicit information and the relatively simple relationships between response and input variables, the data mining method is considered to be a good tool for an in-depth understanding of the mechanisms of blast-induced brain injury. As a general method, this approach can also be applied to other nonlinear complex biomechanical systems. 相似文献