全文获取类型
收费全文 | 1175篇 |
免费 | 41篇 |
国内免费 | 4篇 |
专业分类
1220篇 |
出版年
2024年 | 5篇 |
2023年 | 19篇 |
2022年 | 43篇 |
2021年 | 48篇 |
2020年 | 45篇 |
2019年 | 63篇 |
2018年 | 50篇 |
2017年 | 38篇 |
2016年 | 56篇 |
2015年 | 65篇 |
2014年 | 71篇 |
2013年 | 104篇 |
2012年 | 65篇 |
2011年 | 96篇 |
2010年 | 50篇 |
2009年 | 46篇 |
2008年 | 33篇 |
2007年 | 36篇 |
2006年 | 35篇 |
2005年 | 30篇 |
2004年 | 29篇 |
2003年 | 19篇 |
2002年 | 19篇 |
2001年 | 2篇 |
2000年 | 7篇 |
1999年 | 5篇 |
1997年 | 3篇 |
1996年 | 2篇 |
1995年 | 7篇 |
1994年 | 4篇 |
1993年 | 3篇 |
1992年 | 4篇 |
1991年 | 10篇 |
1990年 | 15篇 |
1989年 | 12篇 |
1988年 | 16篇 |
1987年 | 13篇 |
1986年 | 4篇 |
1985年 | 7篇 |
1984年 | 12篇 |
1983年 | 2篇 |
1982年 | 4篇 |
1980年 | 4篇 |
1979年 | 4篇 |
1978年 | 4篇 |
1975年 | 3篇 |
1962年 | 1篇 |
1960年 | 1篇 |
1957年 | 1篇 |
1956年 | 1篇 |
排序方式: 共有1220条查询结果,搜索用时 31 毫秒
991.
Najafizadeh Abbas Salajegheh Afshin Rahmani Amir Masoud Sahafi Amir 《Cluster computing》2022,25(1):141-165
Cluster Computing - Fog Computing continues to extend its usage by solving cloud computing challenges about Internet of Things (IoT). Fog nodes as a processing resource, can perform tasks generated... 相似文献
992.
Hidayat Hussain Ahmed Al‐Harrasi Ghulam Abbas Najeeb Ur Rehman Fazal Mabood Ishtiaq Ahmed Muhammad Saleem Teunis van Ree Ivan R. Green Saeed Anwar Amin Badshah Afzal Shah Iftikhar Ali 《化学与生物多样性》2013,10(11):1944-1971
In this review, literature data on phytochemical and biological investigations on the genus Pluchea are compiled. Pluchea is a genus of flowering plants in the Asteraceae family and comprises ca. 80 species distributed mainly in Northern and Southern America, Africa, Asia, and Australia. Sesquiterpenoids and flavonoids are the main constituents of this genus. Compounds isolated from plants of the Pluchea genus display a variety of biological properties, viz., anticancer, antileishmanial, immunosuppressive, antioxidant, anti‐acetylcholinesterase, antimicrobial, trypanocidal, hepatoprotective, cytotoxic, larvicidal, anti‐ulcer, anti‐inflammatory, and antinociceptive activities. 相似文献
993.
T. M. Abbas 《BMJ (Clinical research ed.)》1957,1(5018):563-565
994.
El Barzouhi A Elias-Smale S Dehghan A Vliegenthart-Proença R Oudkerk M Hofman A Witteman JC 《PloS one》2011,6(2):e16738
Background
Coronary artery calcification (CAC) has been proposed to be the underlying mechanism of the increased risk of coronary heart disease with reductions in glomerular filtration rate (GFR). Since renal function diminishes with aging we examined the association between GFR and CAC in the Rotterdam Study, a population-based study of elderly individuals.Methods
The study was performed in 1703 subjects without a history of coronary heart disease. GFR was estimated using the modification of diet in renal disease equation. We used analysis of covariance to test for mean differences in CAC between GFR tertiles.Results
The mean CAC scores in the middle and lowest GFR tertile did not significantly differ from the mean CAC score in the highest GFR tertile (geometric mean CAC score 4.1 and 4.3 vs 4.2). In a multivariable model the mean CAC score did also not differ between the GFR tertiles. As the interaction term between age and GFR was significant (P = 0.037), we divided the population in two age categories based on median age of 70 years. Below 70 years, the mean CAC scores did not differ between the GFR tertiles. Above median age, mean CAC score in the lowest GFR tertile was significantly higher than the mean CAC score in the highest tertile in a multivariable model (CAC 4.9 vs 4.5, p = 0.010).Conclusion
In this population-based study we observed that the association between CAC and GFR is modified by age. In participants at least 70 years of age, a decrease in GFR was associated with increased CAC. 相似文献995.
Khan A Iqbal Z Khan MI Javed K Khan A Ahmad L Shah Y Nasir F 《Journal of chromatography. B, Analytical technologies in the biomedical and life sciences》2011,879(24):2423-2429
A novel isocratic reversed-phase high performance liquid-chromatography/ultraviolet detection method for simultaneous determination of cefdinir and cefixime in human plasma was developed and validated after optimization of various chromatographic conditions and other experimental parameters. Sample preparation based on a simple extraction procedure consisting of deproteination and extraction with 3 parts of 6% trichloroacetic acid aqueous solution followed by volume make up with the aqueous component of the mobile phase obtained best recoveries of the two analytes. Samples were separated on a Supelco Discovery HS C(18) (150 mm × 4.6 mm, 5 μm) analytical column protected by a Perkin Elmer C(18) (30 mm × 4.6 mm, 10 μm) guard cartridge. The mobile phase, methanol/acetonitrile (50/50, v/v):0.05% trifluoroacetic acid (19:81, v/v), operated at 50°C column oven temperature was pumped at a flow rate of 2.0 mL min(-1) and the column eluents were monitored at a wavelength of 285 nm. When Sample was injected into the Perkin Elmer high performance liquid-chromatography system through Rheodyne manual (or auto-sampler) injector equipped with 20 μL loop, separation was achieved within 4 min. The present method demonstrated acceptable values for selectivity, linearity within the expected concentration range (0.004-5.0 μg mL(-1); r(2)>0.999 for both analytes), recovery (>95% for cefdinir and >96% for cefixime), precision (%RSD<2.0 for cefdinir and <2.2 for cefixime), sensitivity (limit of detection: 1 ng mL(-1) and lower limit of quantification: 4 ng mL(-1) for both analytes), stability of solutions, and robustness. The method was efficiently applied to a pharmacokinetic study in healthy volunteers. 相似文献
996.
997.
Nacer Eddine Abbas Jean Edmond Toublanc Chafika Boucekkine Marianne Toublanc Nabeel A. Affara Jean-Claude Job Marc Fellous 《Human genetics》1990,84(4):356-360
Summary We have studied nine patients aged 1 month to 16 years with 46, XX karyotypes and testicular tissue. Some of these patients were followed through puberty. Phenotypically, two presented normal and seven abnormal external genitalia (AG). Among this latter group, four showed hypospadias and three true hermaphroditism (TH). The endocrine data were similar in all three groups: testosterone levels were within normal limits during puberty, decreasing in adulthood; gonadotrophin levels were above the control values at mid puberty. Histologies of the two sub groups of AG patients were identical up to 5 years of age and presented differences when compared with controls, regardless of the ovarian part of the ovotestis. However, in patients older than 8 years, germ cells disappeared and dysgenesis became obvious. In one patient, the ovarian zone of the gonad was detected only after complete serial sections of the removed gonad were examined. Southern blot analysis with Y-DNA probes displayed Y-specific material for the classic 46 XX males and a lack of such sequences for all patients with AG and TH. Based on these findings, we postulate that 46, XX males with AG and 46, XX TH may represent altenative manifestations of the same genetic defect. These data together with those concerning familial cases of 46, XX males with AG and 46, XX TH suggest an autosomally (or pseudoautosomally) determined mechanism. 相似文献
998.
Nacer Abbas Giuseppe Novelli Narcisio Carlo Stella Onofrio Triolo Francesco Corrado Marc Fellous Michèle Chery Simone Gilgenkrantz Bruno Dallapiccola 《Human genetics》1990,86(1):94-98
Summary A 45,X complement was found in lymphocyte and fibroblast cultures of a male infant with severe growth and mental retardation and mild dysmorphism. Lymphocyte DNA from this patient was found to contain Yp chromosome sequences. In situ hybridization (ISH) with the 50f2 probe led to a clear assignment of euchromatic material on the short arm of chromosome 1. This observation and others from the literature argue in favour of the conclusion that all 45.X males are probably either the result of undetected mosaicism or are carriers of Y translocated material. 相似文献
999.
Each of 12 cultures ofFusarium, comprising four species, isolated from moldy soybeans suspected of being involved in illness of wild geese, were grown separately in autoclaved moist rice, in autoclaved moist soybeans, and in surface sterilized-disinfected soybeans, assayed for various mycotoxins, and fed to rats. Four additional cultures that produced known toxins on rice were also grown on soybeans as controls. All isolates, except one ofF moniliforme, grown in rice resulted in weight loss of rats, and that one resulted in weight gain; 12 of the isolates caused death. One isolate ofF poae grown in soybeans caused death when consumed by rats, but none of the other 15 resulted in weight loss or overt injury. Much larger amounts of zearalenone, deoxynivalenol (DON), T-2 toxin, neosolaniol, T-2 tetraol, wortmannin, and moniliformin were produced by the cultures on rice than on soybeans, but more HT-2 toxin was produced by one isolate ofF poae grown on soybeans than when grown on rice. Soybeans appear to be a poor substrate for elaboration of most of the toxins produced by the isolates tested. 相似文献
1000.
Hybrids resulting from crosses between Baccharis sarothroides and B. pilularis (FS1), B. sarothroides (FS2) and B. megapotamica (FS3) were tested for their tolerance to trichothecenes as well as their ability to metabolize the toxins. B. sarothroides (desert broom) was placed in an aqueous solution containing 500 ppm of T-2 toxin and showed visible signs of toxicity on the twigs at 21 h after exposure but not at 6 h, indicating some resistance. Samples of the twigs harvested 6 and 21 h after treatment contained, respectively, T-2 (0.03 and 2.2 micrograms/g), HT-2 (0.09 and 7.6 micrograms/g), and T-2-tetraol (2.1 and 2.6 micrograms/g). The hybrid FS1 showed no signs of toxicity 6 h after treatment, and its twigs contained T-2 (0.8 micrograms/g), HT-2 (10.2 micrograms/g), and T-2-tetraol (10.8 micrograms/g). The leaves at 6 h contained 0.5 micrograms of T-2, 1.7 micrograms of HT-2, 0.01 microgram of 3'-hydroxy-HT-2, and 41 micrograms of T-2-tetraol per g. At 21 h, toxic signs were apparent and the twigs contained T-2 (39 micrograms/g), HT-2 (62 micrograms/g), 3'-hydroxy-HT-2 (0.8 microgram/g), and T-2-tetraol (22 micrograms/g).(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献