全文获取类型
收费全文 | 1466篇 |
免费 | 100篇 |
国内免费 | 37篇 |
出版年
2023年 | 21篇 |
2022年 | 33篇 |
2021年 | 54篇 |
2020年 | 60篇 |
2019年 | 77篇 |
2018年 | 64篇 |
2017年 | 54篇 |
2016年 | 67篇 |
2015年 | 86篇 |
2014年 | 94篇 |
2013年 | 127篇 |
2012年 | 103篇 |
2011年 | 124篇 |
2010年 | 69篇 |
2009年 | 64篇 |
2008年 | 54篇 |
2007年 | 51篇 |
2006年 | 43篇 |
2005年 | 42篇 |
2004年 | 41篇 |
2003年 | 27篇 |
2002年 | 29篇 |
2001年 | 2篇 |
2000年 | 11篇 |
1999年 | 13篇 |
1998年 | 5篇 |
1997年 | 3篇 |
1996年 | 3篇 |
1995年 | 9篇 |
1994年 | 9篇 |
1993年 | 5篇 |
1992年 | 9篇 |
1991年 | 11篇 |
1990年 | 16篇 |
1989年 | 15篇 |
1988年 | 22篇 |
1987年 | 15篇 |
1986年 | 6篇 |
1985年 | 9篇 |
1984年 | 14篇 |
1983年 | 5篇 |
1982年 | 7篇 |
1981年 | 2篇 |
1980年 | 4篇 |
1979年 | 5篇 |
1978年 | 4篇 |
1975年 | 4篇 |
1960年 | 1篇 |
1957年 | 1篇 |
1956年 | 2篇 |
排序方式: 共有1603条查询结果,搜索用时 265 毫秒
1.
R N Mitchell A C Shaw Y K Weaver P Leder A K Abbas 《The Journal of biological chemistry》1991,266(14):8856-8860
Membrane-bound immunoglobulin (mIg) is the antigen receptor on B lymphocytes mediating early events in antigen presentation and signal transduction. Wild-type human mIgM constructs transfected into the murine B-cell lymphoma A20 are expressed as transmembrane proteins with antigen presentation and signaling functions comparable to the endogenous mIgG2A; the transfected wild-type mIgM is internalized rapidly after anti-Ig cross-linking. Transfected constructs lacking the normal three-amino acid cytoplasmic tail are expressed exclusively as phosphatidylinositol-linked proteins, lack both antigen presentation and signal transduction functions, and are internalized slowly following anti-Ig binding. The molecular mass of the cytoplasmic tail-deleted phosphatidylinositol-linked Ig molecule is consistent with cleavage of the transmembrane residues during processing. Cytoplasmic domains may therefore regulate the mode of expression of membrane proteins and thereby influence their functional capabilities. 相似文献
2.
3.
Condon Tom Hakim Abbas Moran Antonio B. Zenteno Blumstein Daniel T. 《Journal of Ethology》2021,39(1):89-96
Journal of Ethology - Animals emit predator-elicited calls in response to potential predation threats. These vocalizations induce a variety of anti-predator behaviors in conspecific receivers... 相似文献
4.
5.
A. Abbas 《Journal of Zoology》1991,224(3):385-401
The diet of coypu ( Myocastor coypus ) on two sites in a managed marsh was investigated by field observations and microscopic analysis of faeces. The habitat is mainly grazing pasture and over 51% of the plant fragments recovered from faeces were leaves of Graminaceae. Other food included hydrophytes, Cyperaceae, dicotyledons, flowers and seeds of Graminaceae and various roots. The mean annual diet of coypu was similar at both sites and showed moderate interannual variations. Relative proportions of different foods varied with season and availability. Hydrophytes, mostly Lemnaceae, were preferentially selected in late summer and autumn. Coypu fed on roots during winter, particularly in periods of exceptional food shortage due to flooding and severe frost. Even when crops were available, coypu utilized a wide range of food. The study shows the importance of feeding strategy in the ability of coypu to colonize new habitats, particularly those which are man-made. 相似文献
6.
Hamidreza Kheiri Manjili Leila Ma’mani Sharareh Tavaddod Maedeh Mashhadikhan Abbas Shafiee Hossein Naderi-Manesh 《PloS one》2016,11(3)
A novel design of gold-coated iron oxide nanoparticles was fabricated as a potential delivery system to improve the efficiency and stability of d, l-sulforaphane as an anticancer drug. To this purpose, the surface of gold-coated iron oxide nanoparticles was modified for sulforaphane delivery via furnishing its surface with thiolated polyethylene glycol-folic acid and thiolated polyethylene glycol-FITC. The synthesized nanoparticles were characterized by different techniques such as FTIR, energy dispersive X-ray spectroscopy, UV-visible spectroscopy, scanning and transmission electron microscopy. The average diameters of the synthesized nanoparticles before and after sulforaphane loading were obtained ∼ 33 nm and ∼ 38 nm, respectively, when ∼ 2.8 mmol/g of sulforaphane was loaded. The result of cell viability assay which was confirmed by apoptosis assay on the human breast cancer cells (MCF-7 line) as a model of in vitro-cancerous cells, proved that the bare nanoparticles showed little inherent cytotoxicity, whereas the sulforaphane-loaded nanoparticles were cytotoxic. The expression rate of the anti-apoptotic genes (bcl-2 and bcl-xL), and the pro-apoptotic genes (bax and bak) were quantified, and it was found that the expression rate of bcl-2 and bcl-xL genes significantly were decreased when MCF-7 cells were incubated by sulforaphane-loaded nanoparticles. The sulforaphane-loaded into the designed gold-coated iron oxide nanoparticles, acceptably induced apoptosis in MCF-7 cells. 相似文献
7.
Plasmonics - A new framework of high-selective plasmonic-induced reflectance (PIR) in a plasmonic-induced transparency (PIT) system is presented by using planar dielectric-metal-dielectric (DMD)... 相似文献
8.
Masoud Doroodgar Mahdi Delavari Moein Doroodgar Ali Abbasi Ali Akbar Taherian Abbas Doroodgar 《The Korean journal of parasitology》2016,54(1):9-14
Tamoxifen is an antagonist of the estrogen receptor and currently used for the treatment of breast cancer. The current treatment of cutaneous leishmaniasis with pentavalent antimony compounds is not satisfactory. Therefore, in this study, due to its antileishmanial activity, effects of tamoxifen on the growth of promastigotes and amastigotes of Leishmania major Iranian strain were evaluated in vitro. Promastigotes and amastigotes were treated with different concentrations (1, 5, 10, 20, and 50 μg/ml) and time periods (24, 48, and 72 hr) of tamoxifen. After tamoxifen treatment, MTT assay (3-[4,5-dimethylthiazol-2-yl]-2,5 biphenyl tetrazolium bromide assay) was used to determine the percentage of live parasites and Graph Pad Prism software to calculate IC50. Flow cytometry was applied to investigate the induction of tamoxifen-induced apoptosis in promastigotes. The half maximal inhibitory concentration (IC50) of tamoxifen on promastigotes was 2.6 μg/ml after 24 hr treatment. Flow cytometry analysis showed that tamoxifen induced early and late apoptosis in Leishmania promastigotes. While after 48 hr in control group the apoptosis was 2.0%, the 50 µg/L concentration of tamoxifen increased it to 59.7%. Based on the in vitro antileishmanial effect, tamoxifen might be used for leishmaniasis treatment; however, further researches on in vivo effects of tamoxifen in animal models are needed. 相似文献
9.
10.
S. Ali M. A. Farooq M. M. Jahangir F. Abbas S. A. Bharwana G. P. Zhang 《Biologia Plantarum》2013,57(4):758-763
The effect of nitrogen forms on photosynthesis and anti-oxidative systems of barley plants under chromium stress was studied in a hydroponic experiment. The treatments comprised three chromium concentrations (0, 75, and 100 μM) and three N forms (NH4)2SO4, urea, and Ca(NO3)2. In comparison with the urea or (NH4)2SO4 fed plants, the Ca(NO3)2 fed plants had higher net photosynthetic rate, intercellular CO2 concentration, stomatal conductance, transpiration rate, photosynthetically active radiation utilization efficiency, variable to maximum chlorophyll fluorescence ratio, and the content of chlorophylls and carotenoids. Cr toxicity caused oxidative stress in all plants but the Ca(NO3)2 fed plants had the least oxidative stress. Moreover, the Ca(NO3)2 fed plants had higher activities of anti-oxidative enzymes and content of non-enzymatic antioxidants than the urea or (NH4)2SO4 fed plants. In addition, the Ca(NO3)2 fed plants had higher N and lower Cr content in all plant tissues than the urea or (NH4)2SO4 fed plants. The current results indicate that the reasonable choice of N fertilizer is important for barley production on the Cr-contaminated soils. 相似文献