全文获取类型
收费全文 | 3124篇 |
免费 | 210篇 |
国内免费 | 1篇 |
出版年
2023年 | 14篇 |
2022年 | 19篇 |
2021年 | 74篇 |
2020年 | 26篇 |
2019年 | 49篇 |
2018年 | 37篇 |
2017年 | 42篇 |
2016年 | 62篇 |
2015年 | 144篇 |
2014年 | 161篇 |
2013年 | 206篇 |
2012年 | 230篇 |
2011年 | 242篇 |
2010年 | 161篇 |
2009年 | 135篇 |
2008年 | 183篇 |
2007年 | 222篇 |
2006年 | 195篇 |
2005年 | 168篇 |
2004年 | 181篇 |
2003年 | 151篇 |
2002年 | 127篇 |
2001年 | 24篇 |
2000年 | 24篇 |
1999年 | 23篇 |
1998年 | 25篇 |
1997年 | 30篇 |
1996年 | 15篇 |
1995年 | 21篇 |
1994年 | 19篇 |
1993年 | 15篇 |
1992年 | 26篇 |
1991年 | 15篇 |
1990年 | 19篇 |
1989年 | 11篇 |
1988年 | 14篇 |
1987年 | 13篇 |
1986年 | 11篇 |
1985年 | 11篇 |
1984年 | 17篇 |
1983年 | 11篇 |
1982年 | 25篇 |
1981年 | 21篇 |
1980年 | 17篇 |
1979年 | 13篇 |
1978年 | 9篇 |
1977年 | 6篇 |
1975年 | 7篇 |
1972年 | 6篇 |
1964年 | 6篇 |
排序方式: 共有3335条查询结果,搜索用时 171 毫秒
991.
992.
993.
Tian Y Breedveld GJ Huang S Oostra BA Heutink P Lo WH 《Biochimica et biophysica acta》2002,1577(1):121-125
ZNF333 is a novel human KRAB-zinc finger protein gene on chromosome 19p13.1 encompassing 14 exons. ZNF333 is highly expressed in heart and encodes a 665 amino acid protein that contains a rare combination of double KRAB-domains, each consisting of a classical KRAB-A and a highly divergent KRAB-B box at the N-terminus. ZNF333 further contains 10 C2H2 zinc finger motifs at the C-terminus. 相似文献
994.
995.
Marion Flechtner‐Mors Herwig H. Ditschuneit Timothy D. Johnson Mark A. Suchard Guido Adler 《Obesity (Silver Spring, Md.)》2000,8(5):399-402
Objective: To investigate the contribution of meal and snack replacements for long‐term weight maintenance and risk factor reduction in obese patients. Research Methods and Procedures: Prospective, randomized, two‐arm, parallel intervention for 12 weeks followed by a prospective single‐arm 4‐year trial in a University Hospital clinic. One hundred patients, >18 years old and with a body mass index > 25 and ≤ 40 kg/m2, were prescribed a 1200 to 1500 kcal/d control diet (Group A) or an isoenergetic diet, including two meal and snack replacements (vitamin‐ and mineral‐fortified shakes, soups, and bars) and one meal high in fruits and vegetables (Group B). Following a 3 months of weight loss, all patients were prescribed the same energy‐restricted diet (1200 to 1500 kcal) with one meal and one snack replacement for an additional 4 years. Results: All 100 patients were evaluated at 12 weeks. Mean percentage weight loss was 1.5 ± 0.4% and 7.8 ± 0.5% (mean ± SEM) for Groups A and B, respectively. At 12 weeks systolic blood pressure, plasma triacylglycerol, glucose, and insulin concentrations were significantly reduced in Group B, whereas no changes occurred in Group A. After 4 years, 75% of the patients were evaluated. Total mean weight loss was 3.2 ± 0.8% for Group A and 8.4 ± 0.8% (mean ± SEM) for Group B. Both groups showed significant improvement in blood glucose and insulin (p < 0.001), but only Group B showed significant improvement in triacylglycerol and systolic blood pressure compared to baseline values (p < 0.001). Discussion: Providing a structured meal plan via vitamin‐ and mineral‐fortified liquid meal replacements is a safe and effective dietary strategy for obese patients. Long‐term maintenance of weight loss with meal replacements can improve certain biomarkers of disease risk. 相似文献
996.
997.
998.
Summary The thermal stability of vacuum-dried acid-phosphatase has been investigated, both in the absence and in the presence of pure hexadecane. Preliminary experimental results indicate that: i) in both solid-phase runs, acid-phosphatase is much more stable than the free enzyme in aqueous solution, ii) the presence of the organic solvent slightly reduces thermal stability of the solid-phase enzyme. As regards the deactivation mechanism, when acid-phosphatase operates in free aqueous solution it follows a two-step in series deactivation. Initially the native configuration decays towards an intermediate, still active form. This, in turn, irreversibily yields a totally inactive structure. In the thermal deactivation of solid-phase enzyme it has been observed that: i) the first step is substantially retarded, ii) the final transition is completely hindered, iii) the intermediate configuration is more active than that produced in aqueous solution, by more than one order of magnitude. 相似文献
999.
Adele Cutignano Nadia Lamari Giuliana d’ippolito Emiliano Manzo Guido Cimino Angelo Fontana 《Journal of phycology》2011,47(2):233-243
Oxylipins are oxygenated derivatives of polyunsaturated fatty acids (PUFAs) that act as chemical mediators in many ecological and physiological processes in marine and freshwater diatoms. The occurrence and distribution of these molecules are relatively widespread within the lineage with considerable species‐specific differences due to the variability of both the fatty acids recognized as substrates and the enzymatic transformations. The present review provides a general introduction to recent studies on diatom oxylipins and describes an analytical method for the detection and assessment of these elusive molecules in laboratory and field samples. This methodology is based on selective enrichment of the oxylipin fraction by solvent extraction, followed by parallel acquisition of full‐scan UV and tandem mass spectra on reverse phase liquid chromatography (LC) peaks. The analytical procedure enables identification of potential genetic differences, enzymatic regulation, and ecophysiological conditions that result in different oxylipin signatures, thus providing an effective tool for probing the functional relevance of this class of lipids in plankton communities. Examples of oxylipin measurements in field samples are also provided as a demonstration of the analytical potential of the methodology. 相似文献