全文获取类型
收费全文 | 2335篇 |
免费 | 259篇 |
专业分类
2594篇 |
出版年
2023年 | 6篇 |
2022年 | 20篇 |
2021年 | 34篇 |
2020年 | 26篇 |
2019年 | 35篇 |
2018年 | 44篇 |
2017年 | 49篇 |
2016年 | 75篇 |
2015年 | 101篇 |
2014年 | 105篇 |
2013年 | 122篇 |
2012年 | 127篇 |
2011年 | 142篇 |
2010年 | 100篇 |
2009年 | 79篇 |
2008年 | 116篇 |
2007年 | 111篇 |
2006年 | 105篇 |
2005年 | 127篇 |
2004年 | 101篇 |
2003年 | 95篇 |
2002年 | 96篇 |
2001年 | 77篇 |
2000年 | 71篇 |
1999年 | 71篇 |
1998年 | 40篇 |
1997年 | 29篇 |
1996年 | 25篇 |
1995年 | 26篇 |
1994年 | 16篇 |
1993年 | 17篇 |
1992年 | 40篇 |
1991年 | 32篇 |
1990年 | 39篇 |
1989年 | 39篇 |
1988年 | 40篇 |
1987年 | 24篇 |
1986年 | 29篇 |
1985年 | 18篇 |
1984年 | 18篇 |
1983年 | 17篇 |
1982年 | 16篇 |
1981年 | 19篇 |
1980年 | 10篇 |
1979年 | 10篇 |
1978年 | 8篇 |
1975年 | 4篇 |
1974年 | 6篇 |
1973年 | 7篇 |
1971年 | 8篇 |
排序方式: 共有2594条查询结果,搜索用时 15 毫秒
101.
Yao Lu Jose A. Alonso Qiang Yi Liang Lu Zhong Lin Wang Chunwen Sun 《Liver Transplantation》2019,9(28)
Solid‐state sodium batteries (SSSBs) are promising electrochemical energy storage devices due to their high energy density, high safety, and abundant resource of sodium. However, low conductivity of solid electrolyte as well as high interfacial resistance between electrolyte and electrodes are two main challenges for practical application. To address these issues, pure phase Na3Zr2Si2PO12 (NZSP) materials with Ca2+ substitution for Zr4+ are synthesized by a sol‐gel method. It shows a high ionic conductivity of more than 10?3 S cm?1 at 25 °C. Moreover, a robust SSSB is developed by integrating sodium metal anodes into NZSP‐type monolithic architecture, forming a 3D electronic and ionic conducting network. The interfacial resistance is remarkably reduced and the monolithic symmetric cell displays stable sodium platting/striping cycles with low polarization for over 600 h. Furthermore, by combining sodium metal anode with Na3V2(PO4)3 cathode, an SSSB is demonstrated with high rate capability and excellent cyclability. After 450 cycles, the capacity of the cell is still kept at 94.9 mAh g?1 at 1 C. This unique design of monolithic electrolyte architecture provides a promising strategy toward realizing high‐performance SSSBs. 相似文献
102.
103.
Giant unilamellar vesicles electroformed from native membranes and organic lipid mixtures under physiological conditions 总被引:1,自引:0,他引:1
下载免费PDF全文
![点击此处可从《Biophysical journal》网站下载免费的PDF全文](/ch/ext_images/free.gif)
In recent years, giant unilamellar vesicles (GUVs) have become objects of intense scrutiny by chemists, biologists, and physicists who are interested in the many aspects of biological membranes. In particular, this "cell size" model system allows direct visualization of particular membrane-related phenomena at the level of single vesicles using fluorescence microscopy-related techniques. However, this model system lacks two relevant features with respect to biological membranes: 1), the conventional preparation of GUVs currently requires very low salt concentration, thus precluding experimentation under physiological conditions, and 2), the model system lacks membrane compositional asymmetry. Here we show for first time that GUVs can be prepared using a new protocol based on the electroformation method either from native membranes or organic lipid mixtures at physiological ionic strength. Additionally, for the GUVs composed of native membranes, we show that membrane proteins and glycosphingolipids preserve their natural orientation after electroformation. We anticipate our result to be important to revisit a vast variety of findings performed with GUVs under low- or no-salt conditions. These studies, which include results on artificial cell assembly, membrane mechanical properties, lipid domain formation, partition of membrane proteins into lipid domains, DNA-lipid interactions, and activity of interfacial enzymes, are likely to be affected by the amount of salt present in the solution. 相似文献
104.
Murruzzu C Alonso M Canales A Jiménez-Barbero J Riera A 《Carbohydrate research》2007,342(12-13):1805-1812
The synthesis of (4,5,6-13C)-deoxymannojirimycin is described. The route employed is based on Sharpless asymmetric epoxidation of (1,2,3-13C)(E)-2,4-pentadien-1-ol and uses ring-closing metathesis as a key step. The labeled compound may be easily used for protein-binding experiments using NMR spectroscopic methods. 相似文献
105.
Bes-Rastrollo M Sabaté J Gómez-Gracia E Alonso A Martínez JA Martínez-González MA 《Obesity (Silver Spring, Md.)》2007,15(1):107-116
Objective: To assess the association, in a Mediterranean population, between nut consumption and risk of weight gain (at least 5 kg) or the risk of becoming overweight/obese. Research Methods and Procedures: The Seguimiento Universidad de Navarra project is a prospective cohort of 8865 adult men and women who completed a follow‐up questionnaire after a median of 28 months. Dietary habits were assessed with a previously validated semiquantitative food‐frequency questionnaire. Results: Nine hundred thirty‐seven participants reported a weight gain of ≥5 kg at follow‐up. After adjusting for age, sex, smoking, leisure time physical activity, and other known risk factors for obesity, participants who ate nuts two or more times per week had a significantly lower risk of weight gain (odds ratio: 0.69; 95% confidence interval: 0.53 to 0.90, p for trend = 0.006) than those who never or almost never ate nuts. Participants with little nut consumption (never/almost never) gained an average of 424 grams (95% confidence interval: 102 to 746) more than frequent nut eaters. Nut consumption was not significantly associated with incident overweight/obesity in the cohort. Discussion: Frequent nut consumption was associated with a reduced risk of weight gain (5 kg or more). These results support the recommendation of nut consumption as an important component of a cardioprotective diet and also allay fears of possible weight gain. 相似文献
106.
Ferreirós N Dresen S Alonso RM Weinmann W 《Journal of chromatography. B, Analytical technologies in the biomedical and life sciences》2007,855(2):134-138
Candesartan cilexetil is an angiotensin receptor antagonist widely used in the treatment of high blood pressure. This prodrug is metabolised into candesartan, which blocks the receptors AT1 for angiotensin II decreasing the blood pressure levels. During the development of a solid phase extraction procedure for the chromatographic determination of eight antihypertensive compounds, lack of linearity and reproducibility was observed only for candesartan cilexetil. Due to this fact, a stability study for this prodrug was performed. It showed that the lack of linearity and reproducibility was based on hydrolysis and transesterification processes which occurred during the drying step after elution with methanol into glass tubes. These phenomena could be reproduced artificially under basic conditions, which demonstrated the presence of basic residues in glass tubes. The study of this potential hydrolysis and transesterification reactions is very important to assure that labile drugs containing ester groups remain unaffected. 相似文献
107.
An ozone (O3) deposition model (DO3SE) is currently used in Europe to define the areas where O3 concentrations lead to absorbed O3 doses that exceed the flux-based critical levels above which phytotoxic effects would be likely recorded. This mapping exercise relies mostly on the accurate estimation of O3 flux through plant stomata. However, the present parameterization of the modulation of stomatal conductance (g(s)) behavior by different environmental variables needs further adjustment if O3 phytotoxicity is to be assessed accurately at regional or continental scales. A new parameterization of the model is proposed for Holm oak (Quercus ilex), a tree species that has been selected as a surrogate for all Mediterranean evergreen broadleaf species. This parameterization was based on a literature review, and was calibrated and validated using experimentally measured data of g(s) and several atmospheric and soil parameters recorded at three sites of the Iberian Peninsula experiencing long summer drought, and very cold and dry winter air (El Pardo and Miraflores) or milder conditions (Tietar). A fairly good agreement was found between modeled and measured data (R2 = 0.64) at Tietar. However, a reasonable performance (R2 = 0.47-0.62) of the model was only achieved at the most continental sites when g(s) and soil moisture deficit relationships were considered. The influence of root depth on g(s) estimation is discussed and recommendations are made to build up separate parameterizations for continental and marine-influenced Holm oak sites in the future. 相似文献
108.
109.
M.B. Barroso R.M. Jiménez R.M. Alonso E. Ortiz 《Journal of chromatography. B, Analytical technologies in the biomedical and life sciences》1996,675(2):303
A high-performance liquid chromatographic method with electrochemical detection (ED) has been developed for the determination of two diuretics: 4-phenoxy-3-(1-pyrrolidinyl)-5-sulfamoylbenzoic acid (piretanide) and 4-chloro-2-furfurylamino-5-sulfamoylbenzoic acid (furosemide). The chromatographic separation was performed on a μBondapak C18 column with a mobile phase of acetonitrile-water (40:60) containing 5 mM KH2PO4/K2HPO4 and with a flow-rate of 1 ml/min (69 bar). The temperature was optimized at 30 ± 0.2°C. The amperometric detector equipped with a glassy carbon electrode was operated at + 1200 mV versus Ag/AgCl in the direct current mode. The method was applied to the determination of these compounds in two concentration ranges (ppm and ppb), obtaining a reproducibility in terms of relative standard deviations lower than 1% for within-day and 4% for day-to-day and determination limits of 15 ppb for both compounds. Recoveries greater than 90% were obtained for spiked urine samples, using a liquid-liquid extraction method in the sample clean-up procedure. The LC-ED method was applied to commercially available pharmaceuticals (Seguril, furosemide 40 mg, and Perbilén, piretanide 6 mg) and urine samples obtained from healthy volunteers and hypertensive patients. 相似文献
110.