全文获取类型
收费全文 | 704篇 |
免费 | 39篇 |
专业分类
743篇 |
出版年
2023年 | 7篇 |
2022年 | 12篇 |
2021年 | 21篇 |
2020年 | 18篇 |
2019年 | 16篇 |
2018年 | 28篇 |
2017年 | 16篇 |
2016年 | 24篇 |
2015年 | 23篇 |
2014年 | 50篇 |
2013年 | 43篇 |
2012年 | 43篇 |
2011年 | 50篇 |
2010年 | 21篇 |
2009年 | 20篇 |
2008年 | 27篇 |
2007年 | 33篇 |
2006年 | 33篇 |
2005年 | 25篇 |
2004年 | 26篇 |
2003年 | 16篇 |
2002年 | 23篇 |
2001年 | 11篇 |
2000年 | 27篇 |
1999年 | 21篇 |
1998年 | 12篇 |
1997年 | 10篇 |
1996年 | 9篇 |
1995年 | 5篇 |
1994年 | 6篇 |
1993年 | 4篇 |
1992年 | 14篇 |
1991年 | 5篇 |
1990年 | 3篇 |
1989年 | 6篇 |
1988年 | 4篇 |
1987年 | 4篇 |
1986年 | 2篇 |
1985年 | 3篇 |
1984年 | 2篇 |
1979年 | 3篇 |
1977年 | 1篇 |
1975年 | 1篇 |
1974年 | 2篇 |
1973年 | 2篇 |
1972年 | 1篇 |
1970年 | 1篇 |
1966年 | 3篇 |
1962年 | 2篇 |
1961年 | 1篇 |
排序方式: 共有743条查询结果,搜索用时 15 毫秒
111.
Manna S Chakraborty T Ghosh B Chatterjee M Panda A Srivastava S Rana A Chatterjee M 《Prostaglandins, leukotrienes, and essential fatty acids》2008,79(1-2):5-14
The present study investigated the chemopreventive effect of dietary fish oil (Maxepa), rich in eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) on induction of apoptosis in mammary carcinogenesis model. Mammary carcinogenesis was initiated by a single, tail vein injection of 7,12-dimethylbenz(alpha)anthracene (DMBA) (0.5mg/0.2ml corn oil/100g body weight) at 7 weeks of animal age. Ninety female Sprague-Dawley rats were divided into two parts: part one was used for histology and immunohistochemical study and part two for morphological analysis. Each part consists of three experimental groups having 15 animals, i.e., Group A (DMBA control), Group B (DMBA+fish oil) and Group C (DMBA+corn oil). Rats were fed either fish oil or corn oil (0.5ml/day/rat) by oral gavage, 2 weeks prior to DMBA injection. Treatment was continued 25 weeks, studying histopathology, expression of Bax and Bcl-2 proteins by immunohistochemistry and apoptosis by TUNEL assay and morphological study at 36 weeks. Results showed that the fish oil-treated group exhibited a substantial increase in Bax (p<0.05) immunolabelling and a reduction of Bcl-2 immunopositivity (p<0.05), and increased TUNEL-positive apoptotic cells (p<0.05); however, corn oil treatment did not show these beneficial effects toward mammary preneoplasia. We conclude that fish oil has the potential to play a significant role in limiting mammary tumourigenesis in vivo. 相似文献
112.
Responses of Camellia sinensis to Drought and Rehydration 总被引:2,自引:1,他引:1
The effects of drought and rehydration on tea seedlings were significant. After five days of drought imposition the contents of chlorophylls, carotenoids, ascorbate and glutathione, and activities of guaiacol peroxidase and glutathione reductase decreased. Simultaneously, contents of proline, H2O2 and superoxide anion, lipid peroxidation and activities of catalase and superoxide dismutase increased. These parameters recovered to different degrees during subsequent rehydration. 相似文献
113.
NaCl salt stress induced changes in growth and enzyme activities in blackgram (Phaseolus mungo L.) seeds during germination were studied. A decrease in germination percentage, root length, shoot length, and fresh mass was noticed with an increase in NaCl concentration. With the increase in NaCl concentration and duration of stress proline content increased and catalase (CAT), peroxidase (POX) and polyphenol oxidase (PPO) activities decreased. 相似文献
114.
Imposition of NaCl-salinity stress induced oxidative reactions in root tissue of rice seedlings. A uniform accumulation of
proline was marked with the increasing NaCl concentrations. Both peroxide content and lipid peroxidation level (MDA) increased
with the salt treatment from the control. CAT, GPx and SOD activities decreased with the increasing NaCl concentrations suggesting
a possible oxidative damage to root tissue. 相似文献
115.
Understanding the morphology of fungi 总被引:3,自引:0,他引:3
Filamentous fungi comprise an industrially very important collection of microorganisms, since they are used for the production of a wide variety of products ranging from primary metabolites to secondary metabolites and further on to industrial enzymes (such as proteases, lipases and antibiotics). It is known that fungal morphology is often considered as one of the key parameters in industrial production. For the production of fungal metabolite products, the desired morphology varies from one product to another. Many parameters affect the morphology of fungi during the process of fermentation, among them speed of agitation, specific growth rate, dissolved oxygen, number of spores or conidia per liter of fermentation broth are important and should be considered when higher yield is desired in the process. It is, therefore, of considerable importance to understand the mechanism underlying the morphology of the cell, its growth and product formation by filamentous fungi. Such knowledge may be used in the optimization of the microbial process. Several literatures with various fungi to study their morphology, relating enzyme or product production to the character of the fungi in the study is reviewed. It is also considered that how the process parameters affects the morphology. The aim of this communication is to review the relevant literature to understand the morphology of filamentous fungi. 相似文献
116.
117.
118.
119.
Aruna S. Jaiswal Harekrushna Panda Brian K. Law Jay Sharma Jitesh Jani Robert Hromas Satya Narayan 《PloS one》2015,10(5)
Recently approved chemotherapeutic agents to treat colorectal cancer (CRC) have made some impact; however, there is an urgent need for newer targeted agents and strategies to circumvent CRC growth and metastasis. CRC frequently exhibits natural resistance to chemotherapy and those who do respond initially later acquire drug resistance. A mechanism to potentially sensitize CRC cells is by blocking the DNA polymerase β (Pol-β) activity. Temozolomide (TMZ), an alkylating agent, and other DNA-interacting agents exert DNA damage primarily repaired by a Pol-β-directed base excision repair (BER) pathway. In previous studies, we used structure-based molecular docking of Pol-β and identified a potent small molecule inhibitor (NSC666715). In the present study, we have determined the mechanism by which NSC666715 and its analogs block Fen1-induced strand-displacement activity of Pol-β-directed LP-BER, cause apurinic/apyrimidinic (AP) site accumulation and induce S-phase cell cycle arrest. Induction of S-phase cell cycle arrest leads to senescence and apoptosis of CRC cells through the p53/p21 pathway. Our initial findings also show a 10-fold reduction of the IC50 of TMZ when combined with NSC666715. These results provide a guide for the development of a target-defined strategy for CRC chemotherapy that will be based on the mechanisms of action of NSC666715 and TMZ. This combination strategy can be used as a framework to further reduce the TMZ dosages and resistance in CRC patients. 相似文献
120.
Debabrata Panda Dibyajyoti Panda Bandana Padhan Meghali Biswas 《International journal of phytoremediation》2018,20(6):538-544
Revegetation with metal tolerant plants for management of fly ash deposits is an important environmental perspective nowadays. Growth performance, photosynthesis, and antioxidant defense of lemongrass (Cymbopogon citratus (D.C.) Stapf.) were evaluated under various combination of fly ash amended with garden soil in order to assess its fly ash tolerance potential. Under low level of fly ash (25%) amended soil, the plant growth parameters such as shoot, root, and total plant biomass as well as metal tolerance index were increased compared to the control plants grown on garden soil, followed by decline under higher concentration of fly ash (50%, 75% and 100%). In addition, leaf photosynthetic rate, stomatal conductance, and photosystem (PS) II activity were not significantly changed under low level of fly ash (25%) amended soil compared to the garden soil but these parameters were significantly decreased further with increase of fly ash concentrations. Furthermore, increase of activities of some antioxidant enzymes such as superoxide dismutase, ascorbate peroxidase, and guaiacol peroxidase over control were noticed in lemongrass under all fly ash treatments. Taken together, the study suggests that lemongrass can be used for phytoremediation of fly ash at 25% amended soil. 相似文献