全文获取类型
收费全文 | 978篇 |
免费 | 116篇 |
专业分类
1094篇 |
出版年
2022年 | 5篇 |
2021年 | 9篇 |
2017年 | 6篇 |
2016年 | 14篇 |
2015年 | 15篇 |
2014年 | 24篇 |
2013年 | 31篇 |
2012年 | 47篇 |
2011年 | 36篇 |
2010年 | 26篇 |
2009年 | 32篇 |
2008年 | 55篇 |
2007年 | 37篇 |
2006年 | 46篇 |
2005年 | 38篇 |
2004年 | 37篇 |
2003年 | 31篇 |
2002年 | 24篇 |
2001年 | 35篇 |
2000年 | 44篇 |
1999年 | 33篇 |
1998年 | 12篇 |
1997年 | 27篇 |
1996年 | 14篇 |
1995年 | 15篇 |
1994年 | 21篇 |
1993年 | 12篇 |
1992年 | 23篇 |
1991年 | 24篇 |
1990年 | 24篇 |
1989年 | 27篇 |
1988年 | 24篇 |
1987年 | 21篇 |
1986年 | 8篇 |
1985年 | 17篇 |
1984年 | 17篇 |
1983年 | 17篇 |
1982年 | 13篇 |
1981年 | 18篇 |
1980年 | 7篇 |
1979年 | 9篇 |
1978年 | 15篇 |
1977年 | 10篇 |
1976年 | 9篇 |
1975年 | 10篇 |
1974年 | 7篇 |
1973年 | 14篇 |
1972年 | 4篇 |
1971年 | 5篇 |
1969年 | 6篇 |
排序方式: 共有1094条查询结果,搜索用时 15 毫秒
51.
Marian L. Kruzel Jeffrey K. Actor Michał Zimecki Jasen Wise Paulina Płoszaj Shaper Mirza Mark Kruzel Shen-An Hwang Xueqing Ba Istvan Boldogh 《Journal of biotechnology》2013
Lactoferrin, an iron-binding protein found in high concentrations in mammalian exocrine secretions, is an important component of the host defense system. It is also a major protein of the secondary granules of neutrophils from which is released upon activation. Due to its potential clinical utility, recombinant human lactoferrin (rhLF) has been produced in various eukaryotic expression systems; however, none of these are fully compatible with humans. Most of the biopharmaceuticals approved by the FDA for use in humans are produced in mammalian expression systems. The Chinese hamster ovary cells (CHO) have become the system of choice for proteins that require post-translational modifications, such as glycoproteins. 相似文献
52.
53.
54.
Strobilanthes glutinosa is described and illustrated. It is a winter‐flowering species native to the foothills of the northwestern Himalayas. Although frost sensitive, it appears to flourish as a cultivated plant in shaded places enjoying a mild moist climate. 相似文献
55.
Natasha D. Phillips Amy Garbett Daniel Wise Sophie L. Loca Olivia Daly Lawrence E. Eagling Jonathan D. R. Houghton Peter Verhoog James Thorburn Patrick C. Collins 《Journal of fish biology》2021,99(4):1492-1496
Essential fish habitats (EFHs) are critical for fish life-history events, including spawning, breeding, feeding or growth. This study provides evidence of EFHs for the critically endangered flapper skate (Dipturus intermedius) in the waters around the Orkney Isles, Scotland, based on citizen-science observation data. The habitats of potential egg-laying sites were parametrised as >20 m depth, with boulders or exposed bedrock, in moderate current flow (0.3–2.8 knots) with low sedimentation. This information provides a significant contribution to the understanding of EFHs for flapper skate. 相似文献
56.
John A. Walker II Jiong J. Chen Jack M. Hinkley Dean S. Wise Leroy B. Townsend 《Nucleosides, nucleotides & nucleic acids》2013,32(10-11):1999-2012
Abstract The palladium-catalyzed cross-couplings of 2-chloro-3,5-diamino-6-iodopyrazine (1a) and methyl 3-amino-6-iodopyrazine-2-carboxylate (1b) with 1,4-anhydro-3,5-O-bis[(tert-butyl)dimethylsilyl]-2-deoxy-D-erythro-pent-1-enitol (2) followed by desilylation and stereospecific reduction of the 2′-deoxy-3′-keto adduct leads to the formation of 2-chloro-6-(2-deoxy-ß-D-ribofuranosyl)-3,5-diaminopyrazine (4a) and methyl 3-amino-6-(2-deoxy-ß-D-ribofuranosyl)pyrazine-2-carboxylate (4b) in 58% yield and 21% yield, respectively. These are the first syntheses of the heretofore unknown 2′-deoxy pyrazine C-nucleosides and demonstrate the utility of a convergent approach for the synthesis of pyrazine C-nucleosides. 相似文献
57.
Frank Rattay Thomas Potrusil Cornelia Wenger Andrew K. Wise Rudolf Glueckert Anneliese Schrott-Fischer 《PloS one》2013,8(11)
Background
Our knowledge about the neural code in the auditory nerve is based to a large extent on experiments on cats. Several anatomical differences between auditory neurons in human and cat are expected to lead to functional differences in speed and safety of spike conduction.Methodology/Principal Findings
Confocal microscopy was used to systematically evaluate peripheral and central process diameters, commonness of myelination and morphology of spiral ganglion neurons (SGNs) along the cochlea of three human and three cats. Based on these morphometric data, model analysis reveales that spike conduction in SGNs is characterized by four phases: a postsynaptic delay, constant velocity in the peripheral process, a presomatic delay and constant velocity in the central process. The majority of SGNs are type I, connecting the inner hair cells with the brainstem. In contrast to those of humans, type I neurons of the cat are entirely myelinated. Biophysical model evaluation showed delayed and weak spikes in the human soma region as a consequence of a lack of myelin. The simulated spike conduction times are in accordance with normal interwave latencies from auditory brainstem response recordings from man and cat. Simulated 400 pA postsynaptic currents from inner hair cell ribbon synapses were 15 times above threshold. They enforced quick and synchronous spiking. Both of these properties were not present in type II cells as they receive fewer and much weaker (∼26 pA) synaptic stimuli.Conclusions/Significance
Wasting synaptic energy boosts spike initiation, which guarantees the rapid transmission of temporal fine structure of auditory signals. However, a lack of myelin in the soma regions of human type I neurons causes a large delay in spike conduction in comparison with cat neurons. The absent myelin, in combination with a longer peripheral process, causes quantitative differences of temporal parameters in the electrically stimulated human cochlea compared to the cat cochlea. 相似文献58.
The compulsory dispute settlement regime included in the 1982 Law of the Sea Convention is recognized as one of the most comprehensive in a modern international convention. Yet, in the recent application of this regime, the question has arisen as to whether the procedural prerequisites associated with the LOS Convention's compulsory dispute settlement mechanism are so arduous as to avoid binding and compulsory jurisdiction in most instances. This article addresses that question by examining, in particular, the reasoning of the Southern Bluefin Tuna arbitration tribunal, which found Article 281 of Section 1 of the LOS Convention to bar jurisdiction to the compulsory dispute settlement mechanism prescribed by the Convention, and offers suggestions as to how states might distinguish or overcome the barriers imposed by the Southern Bluefin Tuna tribunal in future cases. 相似文献
59.
Se Li Lynn Rosenberg Julie R. Palmer Ghasi S. Phillips Linda J. Heffner Lauren A. Wise 《Obesity (Silver Spring, Md.)》2013,21(1):178-184
Objective:
Previous studies have consistently identified maternal obesity and gestational weight gain (GWG) as risk factors for macrosomia, but little is known about the effects of central adiposity and body fat distribution. Using self‐reported data from the Black Women's Health Study (BWHS), a large follow‐up study of US black women, we examined the risk of macrosomia in relation to prepregnancy waist circumference, prepregnancy waist‐to‐hip ratio (WHR), prepregnancy BMI, and GWG.Design and Methods:
During 1995–2003, BWHS participants ages 21–44 years delivered 6,687 full‐term singleton births (gestational age >37 weeks). We compared mothers of 691 infants weighing ≥4,000 g with mothers of 5,996 infants weighing <4,000 g. Generalized estimating equation models (GEE) that accounted for more than one birth per mother were used to estimate multivariable odds ratios (OR) and 95% confidence intervals (CI).Results:
Independent of prepregnancy BMI, prepregnancy waist circumference was positively associated with risk of macrosomia (OR = 1.58, 95% CI: 1.07–2.32, for ≥35.0 vs. <27.0 inches (≥88.9 vs. <68.6 cm); P trend = 0.04). As expected, prepregnancy BMI was also positively associated with macrosomia (OR = 1.74, 95% CI: 1.25–2.41 for BMI ≥35.0 vs. 18.5–24.9 kg m?2). GWG above the amount recommended by the 2009 Institute of Medicine report was associated with an increased risk of macrosomia and the association was present in each category of prepregnancy BMI (18.5–24.9, 25.0–29.9, and ≥30.0 kg m?2; P trend <0.001).Conclusions:
Our data suggest that overall obesity, high GWG, and high waist circumference are independent risk factors for macrosomia among US black women.60.
Wise LD Turner KJ Kerr JS 《Birth defects research. Part B, Developmental and reproductive toxicology》2007,80(1):57-68
BACKGROUND: The developmental toxicity potential of vorinostat (suberoylanilide hydroxamic acid [SAHA], ZOLINZA), a potent inhibitor of histone deacetylase (HDAC), was assessed in Sprague-Dawley rats and Dutch Belted rabbits. HDAC inhibitors have been shown to mediate the regulation of gene expression, induce cell growth, cell differentiation, and apoptosis of tumor cells. Range-finding studies established oral dose levels of 5, 15, or 50 mg/kg/day and 20, 50, or 150 mg/kg/day in rats and rabbits, respectively. METHODS: Animals were dosed on Gestation Days 6-20 or 7-20, respectively, with litter/fetal parameters evaluated on GD 21 and 28, respectively. Separate studies evaluated toxicokinetic parameters at the mid- and high-dose levels. RESULTS: There was no maternal toxicity observed at the highest dose levels; however, hematology and serum biochemistry changes were characterized in the range-finding studies. Vorinostat did not induce morphological malformations in either rat or rabbit fetuses. In rats, drug-related developmental toxicity was observed only in the high-dose group and consisted of markedly decreased fetal weight and increases in fetuses with a limited number of skeletal variations. In rabbits, drug-related developmental toxicity was also observed only in the high-dose group and consisted of slightly decreased fetal weight and increases in fetuses with a short 13th rib and incomplete ossification of metacarpals. Maternal exposures to vorinostat based on AUC and Cmax values were comparable at the high-dose levels of both species. Rabbits tolerated higher dosages probably due to more extensive metabolism. Maternal concentrations of vorinostat were approximately 1,000-fold above the known in vitro HDAC inhibitory concentration. CONCLUSIONS: Review of previous work with valproic acid, another HDAC inhibitor, suggest that the developmental toxicity profiles of these 2 compounds are not the result of HDAC inhibition but involve other mechanisms. 相似文献