全文获取类型
收费全文 | 1134篇 |
免费 | 58篇 |
专业分类
1192篇 |
出版年
2023年 | 6篇 |
2022年 | 12篇 |
2021年 | 20篇 |
2020年 | 13篇 |
2019年 | 26篇 |
2018年 | 29篇 |
2017年 | 29篇 |
2016年 | 27篇 |
2015年 | 40篇 |
2014年 | 53篇 |
2013年 | 69篇 |
2012年 | 79篇 |
2011年 | 83篇 |
2010年 | 63篇 |
2009年 | 44篇 |
2008年 | 53篇 |
2007年 | 63篇 |
2006年 | 48篇 |
2005年 | 66篇 |
2004年 | 45篇 |
2003年 | 32篇 |
2002年 | 50篇 |
2001年 | 24篇 |
2000年 | 18篇 |
1999年 | 18篇 |
1998年 | 14篇 |
1997年 | 7篇 |
1996年 | 10篇 |
1995年 | 8篇 |
1994年 | 4篇 |
1993年 | 12篇 |
1992年 | 14篇 |
1991年 | 8篇 |
1990年 | 9篇 |
1989年 | 11篇 |
1988年 | 7篇 |
1987年 | 12篇 |
1986年 | 2篇 |
1985年 | 4篇 |
1984年 | 2篇 |
1983年 | 3篇 |
1982年 | 10篇 |
1981年 | 10篇 |
1980年 | 6篇 |
1979年 | 12篇 |
1978年 | 6篇 |
1974年 | 3篇 |
1973年 | 2篇 |
1964年 | 1篇 |
1944年 | 1篇 |
排序方式: 共有1192条查询结果,搜索用时 15 毫秒
71.
Fleischman D Edwards GE Govindjee Mayne L Tyagi V Jacobsen-Mispagel K 《Photosynthesis research》2012,112(2):81-89
We provide here insights on the life and work of Berger C. Mayne (1920-2011). We remember and honor Berger, whose study of photosynthesis began with the most basic processes of intersystem electron transport and oxygen evolution, continued with application of fluorescence techniques to the study of photophosphorylation and the unique features of photosystems in specialized cells, and concluded with collaborative study of photosynthesis in certain nitrogen fixing symbioses. Berger loved the outdoors and was dedicated to preserving the environment and to social justice, and was a wonderful friend. 相似文献
72.
Although there is no evidence of significant Na-independent glucose flux in tissues naturally expressing SGLT1, previous kinetic and biophysical studies suggest that sodium/d-glucose cotransporter 1 (hSGLT1) can facilitate sodium-independent d-glucose transport and may contain more than one sugar binding site. In this work, we analyze the kinetic properties and conformational states of isolated hSGLT1 reconstituted in liposomes by transport and fluorescence studies in the absence of sodium. In the transport studies with hSGLT1, significant sodium-independent phlorizin inhibitable alpha-methyl d-glucopyranoside (alpha-MDG) uptake was observed which amounted to approximately 20% of the uptake observed in the presence of a sodium gradient. The apparent affinity constant for alpha-MDG was thereby 3.4 +/- 0.5 mM, a value approximately 10-fold higher than that in the presence of sodium. In the absence of sodium, various sugars significantly decreased the intrinsic Trp fluorescence of hSGLT1 in proteoliposomes exhibiting the following sequence of affinities: alpha-MDG > d-glucose approximately d-galactose > 6-deoxy-d-glucose > 2-deoxy-d-glucose > d-allose. Furthermore, significant protection effects of d-glucose or phlorizin against potassium iodide, acrylamide, or trichloroethanol quenching were observed. To locate the Trps involved in this reaction, we generated mutants in which all Trps were sequentially substituted with Phe. None of the replacements significantly affected sodium-dependent uptake. Uptake in the absence of sodium and typical fluorescence changes depended, however, on the presence of Trp at position 561. This Trp residue is conserved in all known SGLT1 forms (except Vibrio parahaemolyticus SGLT) and all SGLT isoforms in humans (except hSGLT3). If all these data are taken into consideration, it seems that Trp-561 in hSGLT1 forms part of a low-affinity sodium-independent binding and/or translocation site for d-glucose. The rate of sodium-independent translocation via hSGLT1 seems, however, to be tightly regulated in the intact cell by yet unknown factors. 相似文献
73.
H. S. Dhaliwal B. R. Tyagi F. W. White B. S. Gill 《Journal of plant biochemistry and biotechnology.》1992,1(2):127-128
Plasmid DNA (CaMVGUS, containing β-glucuronldase gene) was used to transform developing seed of wheat and tobacco through pollen-tube pathway. The DNA was applied on the ovule end of excised styles and stigmas of wheat and tobacco after pollination. None of the 272 wheat and 13,567 tobacco plants obtained after application of the isolated DNA showed β-glucuronidase activity suggesting that the pollen-tube pathway may not be effective for transformation of plants. 相似文献
74.
75.
Chaturvedi V Parakh N Trehan V Tyagi S 《Indian pacing and electrophysiology journal》2011,11(6):173-175
We describe an uncommon case of typical flutter with symptomatic sinus node dysfunction, in which a permanent junctional rhythm developed following ablation of the cavo-tricuspid isthmus. This rhythm activated the right atrium in counter clockwise manner thus providing spontaneous proof of unidirectional isthmus block, a phenomenon that is usually demonstrated by proximal coronary sinus pacing. 相似文献
76.
Arun Goyal D. P. Tyagi Sarvagya S. Katiyar 《Journal of enzyme inhibition and medicinal chemistry》2013,28(1):111-113
Amino acid analysis of purified dextransucrase (sucrose: 1,6-α-D-glucan 6-α-D-glucosyltransferase EC 2.4.1.5) from Leuconostoc mesenteroides NRRL B-512F was carried out. The enzyme is virtually devoid of cysteine residue there being only one cysteine residue in the whole enzyme molecule comprising over 1500 amino acid residues. The enzyme is rich in acidic amino acid residues. The number of amino acid residues was calculated based on the molecular weight of 188,000 (Goyal and Katiyar 1994). Amino sugars were not found, implying that the enzyme is not a glycoprotein. It has been shown earlier that the cysteine residue in dextransucrase is not essential for enzyme activity (Goyal and Katiyar 1998). The presence of only one cysteine residue per enzyme molecule illustrates that its tertiary structure is solely dependent on other types of non-covalent interactions such as hydrogen bonding, ionic and nonpolar hydrophobic interactions. 相似文献
77.
78.
79.
Agarwal-Mawal A Murray CM Belkhode S Cheema SK 《Canadian journal of physiology and pharmacology》2007,85(3-4):430-438
We investigated whether expression of cholesterol ester transfer protein (CETP) in mice alters the regulation of cholesterol metabolism. Transgenic mice expressing human CETP (CETP-TG) and nontransgenic littermates (non-TG) were fed either a monounsaturated fatty acid (MUFA) or a saturated fatty acid (SFA)-rich diet in the presence or absence of cholesterol. Mice fed with MUFA diet had higher CETP activity compared with SFA-fed mice. Addition of cholesterol to the MUFA diet decreased CETP activity, whereas addition of cholesterol to the SFA diet had no effect. Cholesterol 7alpha-hydroxylase (Cyp7a) activity was higher in CETP-TG mice compared with non-TG mice when fed a MUFA diet, whereas SFA fed CETP-TG mice showed lower Cyp7a activity as compared with non-TG. Microsomal triglyceride transfer protein (MTTP) activity was higher in CETP-TG mice compared with non-TG mice when fed a MUFA diet. HMG-CoA reductase activity was lower in CETP-TG mice compared with non-TG mice when fed a MUFA or a SFA diet. These data demonstrate that the regulation of Cyp7a, HMG-CoA reductase, and MTTP is altered in CETP-TG mice as compared with non-TG mice and these alterations are further modulated by the quality of dietary fats. These findings highlight the importance of CETP in regulating cholesterol homeostasis. 相似文献
80.
Naresh Golla Alka Chopra Sanjanna Boya Thota Venkata Chaitanya Kumar Suneel Kumar Onteru Dheer Singh 《Journal of cellular physiology》2019,234(6):7725-7733
Lactation is a highly demanding event in mammals, including buffaloes. It modulates the partitioning of nutrients, energy utilization, and food intake of the mother to meet her own and infant's energy needs. Failure to satisfy these energy needs leads to Negative Energy Balance (NEB). Currently, the only available indirect NEB indicator is Body Condition Score (BCS). However, direct dependency of the BCS on the peak depletion of body fat causes its inefficient use in a dairy farm. Thus, to establish objective NEB indicators in buffaloes, the serum levels of biochemical (serum β-hydroxybutyrate [BHBA] and free fatty acids [FFAs]), and endocrine (Growth Hormone [GH], insulin-like growth factor1 [IGF1], Insulin, and leptin) parameters were estimated in buffaloes. Our results revealed that serum FFA levels were significantly (p < 0.05) higher in high milk yielders (HMY) than low milk yielders (LMY) and heifers (H) during the 3rd and the 4th weeks of postpartum. The serum FFA levels were also significantly (p < 0.001) higher in the postpartum buffaloes with BCS < 3 in the field conditions. Further, serum leptin levels were significantly (p < 0.05) lower in HMY than LMY during the 3rd week of postpartum. However, the BHBA, GH, IGF1, and insulin levels were not significantly different between lactating buffaloes and H. These observations indicated that the NEB condition is probably restricted to the first month of early lactation in buffaloes. In conclusion, the simultaneous higher FFA and lower leptin levels could act as direct plausible metabolic indicators of NEB in buffaloes. 相似文献