全文获取类型
收费全文 | 3788篇 |
免费 | 440篇 |
出版年
2021年 | 47篇 |
2020年 | 45篇 |
2019年 | 52篇 |
2018年 | 52篇 |
2017年 | 46篇 |
2016年 | 78篇 |
2015年 | 117篇 |
2014年 | 123篇 |
2013年 | 152篇 |
2012年 | 216篇 |
2011年 | 206篇 |
2010年 | 116篇 |
2009年 | 123篇 |
2008年 | 166篇 |
2007年 | 154篇 |
2006年 | 142篇 |
2005年 | 132篇 |
2004年 | 151篇 |
2003年 | 143篇 |
2002年 | 143篇 |
2001年 | 88篇 |
2000年 | 85篇 |
1999年 | 73篇 |
1998年 | 44篇 |
1997年 | 41篇 |
1996年 | 32篇 |
1995年 | 40篇 |
1994年 | 41篇 |
1993年 | 42篇 |
1992年 | 63篇 |
1991年 | 69篇 |
1990年 | 80篇 |
1989年 | 73篇 |
1988年 | 67篇 |
1987年 | 84篇 |
1986年 | 67篇 |
1985年 | 89篇 |
1984年 | 46篇 |
1983年 | 48篇 |
1982年 | 38篇 |
1981年 | 46篇 |
1980年 | 35篇 |
1979年 | 43篇 |
1978年 | 37篇 |
1977年 | 45篇 |
1976年 | 41篇 |
1974年 | 47篇 |
1973年 | 34篇 |
1972年 | 37篇 |
1969年 | 30篇 |
排序方式: 共有4228条查询结果,搜索用时 15 毫秒
1.
2.
Mirjam Frischknecht Vidhya Jagannathan Philippe Plattet Markus Neuditschko Heidi Signer-Hasler Iris Bachmann Alicja Pacholewska Cord Dr?gemüller Elisabeth Dietschi Christine Flury Stefan Rieder Tosso Leeb 《PloS one》2015,10(10)
The identification of quantitative trait loci (QTL) such as height and their underlying causative variants is still challenging and often requires large sample sizes. In humans hundreds of loci with small effects control the heritable portion of height variability. In domestic animals, typically only a few loci with comparatively large effects explain a major fraction of the heritability. We investigated height at withers in Shetland ponies and mapped a QTL to ECA 6 by genome-wide association (GWAS) using a small cohort of only 48 animals and the Illumina equine SNP70 BeadChip. Fine-mapping revealed a shared haplotype block of 793 kb in small Shetland ponies. The HMGA2 gene, known to be associated with height in horses and many other species, was located in the associated haplotype. After closing a gap in the equine reference genome we identified a non-synonymous variant in the first exon of HMGA2 in small Shetland ponies. The variant was predicted to affect the functionally important first AT-hook DNA binding domain of the HMGA2 protein (c.83G>A; p.G28E). We assessed the functional impact and found impaired DNA binding of a peptide with the mutant sequence in an electrophoretic mobility shift assay. This suggests that the HMGA2 variant also affects DNA binding in vivo and thus leads to reduced growth and a smaller stature in Shetland ponies. The identified HMGA2 variant also segregates in several other pony breeds but was not found in regular-sized horse breeds. We therefore conclude that we identified a quantitative trait nucleotide for height in horses. 相似文献
3.
4.
Hibernation activates glyoxylate cycle and gluconeogenesis in black bear brown adipose tissue 总被引:1,自引:0,他引:1
W L Davis D B Goodman L A Crawford O J Cooper J L Matthews 《Biochimica et biophysica acta》1990,1051(3):276-278
Biochemical studies on brown adipose tissue removed from a hibernating black bear and a non-hibernating control animal demonstrate that this tissue: (1) can carry out cyanide-insensitive fatty acid oxidation, and (2) possesses catalase activity and the enzyme activities unique to the glyoxylate cycle, isocitrate lyase and malate synthase. These activities are all markedly increased in brown fat obtained from the hibernating animal. Additionally, hibernation enhances the ability of the tissue to synthesize glycogen in the presence of a fatty acid substrate. The glyoxylate cycle enzymes and the ability to convert fatty acid carbons to glucose have been generally regarded as being absent from vertebrate cells and tissues. 相似文献
5.
6.
Craig B. H. Surman David W. Goodman 《Attention deficit and hyperactivity disorders》2017,9(3):161-168
ADHD is a neurodevelopmental syndrome that often persists into adulthood. It is possible that different criteria are necessary for older adults than younger adults: the manifestations of ADHD could change with age; other conditions with onset in later life share presenting symptoms with ADHD; different contextual challenges and patterns of compensatory support may exist. For these reasons, we reviewed evidence for the validity of DSM ADHD criteria in adulthood for individuals over the age of 50. Specifically, we evaluated evidence that the DSM criteria for ADHD identify a valid syndrome in older adults based on clinical presentation, laboratory or testing findings, absence of alternate diagnosis to explain symptoms, course of the syndrome, or familial presence of the condition. We found evidence that various ADHD criteria identify subjects with clinical presentations similar to that seen in younger adults, but only 92 well-described cases have been reported in the literature. ADHD traits also may be less common in the general population of older adults than in younger adults, suggesting that the threshold for an atypical burden of ADHD traits may be lower in older populations. Future research can establish a richer basis for validity of diagnostic criteria for ADHD in older adults. 相似文献
7.
Differential effects of the pharmacological manipulation of serotonin systems on cocaine and amphetamine self-administration in rats 总被引:3,自引:0,他引:3
L J Porrino M C Ritz N L Goodman L G Sharpe M J Kuhar S R Goldberg 《Life sciences》1989,45(17):1529-1535
The effects of the administration of serotonergic drugs on infusion rates of rats self-administering cocaine and amphetamine on an FR-10 schedule of reinforcement in daily 4 hour sessions were compared. Pretreatment with fluoxetine (2.5, 5, and 10 mg/kg), an inhibitor of serotonin reuptake, significantly decreased rates of responding maintained by amphetamine, but had no effect on responding maintained by cocaine at any of the doses tested. Pretreatment with cinanserin (3, 10, and 17.5 mg/kg), a serotonergic receptor antagonist, decreased rates of amphetamine self-administration at the highest dose tested, and also had no effect on cocaine self-administration. These data suggest a differential sensitivity of cocaine and amphetamine self-administration to pharmacological manipulation of central serotonin systems. They are consistent with biochemical data which demonstrates a negative correlation between the reinforcing potency of amphetamine-like drugs, but not cocaine-like drugs and their potency at serotonin binding sites. 相似文献
8.
W O Weigle L C Gahring C G Romball M G Goodman 《Journal of immunology (Baltimore, Md. : 1950)》1989,142(4):1107-1113
As previously reported, LPS and 8-derivatized guanosine (both generators of IL-1 release), as well as IL-1 itself interfere with the in vivo induction of tolerance to DHGG in A/J mice. In the present studies it was demonstrated that desensitization of either A/J or CBA/CaJ mice with LPS aborts the ability of LPS to interfere with the induction of tolerance to DHGG. The abrogation of the ability of LPS to interfere with tolerance by LPS desensitization is not the result of neutralization of LPS by antibody produced to LPS during desensitization. Desensitization with LPS also aborts the interference with tolerance induction by 7-methyl-8-oxoguanosine. LPS desensitization inhibits the ability of LPS and/or 7-methyl-8-oxoguanosine to both convert a tolerogenic signal to an immunogenic signal and interfere with the induction of a tolerant state to a subsequent injection of Ag. The effects resulting from desensitization may be in part attributed to the depletion of IL-1. LPS desensitization also modulates the antibody response to injection of the AG, AHGG. Desensitization with LPS markedly suppresses the antibody response to a subsequent injection of AHGG in CBA/CaJ mice. Desensitization with LPS also inhibits the anti-HGG antibody response in A/J mice, but in this strain its effect is dependent on the route of injection of AHGG. In an experiment directly comparing the responses of normal and desensitized A/J mice to either intravenous or intraperitoneal injection of AHGG, desensitization only suppressed the response in mice injected with AHGG i.p.. Desensitization with LPS also inhibits the ability of LPS to act as an adjuvant in a subsequent antibody response to AHGG. Not only does desensitization interfere with the primary antibody response to AHGG, but it also interferes with the secondary response, suggesting that the primary injection after desensitization induces a state of immunologic tolerance. 相似文献
9.
Iris Pigeot 《Biometrical journal. Biometrische Zeitschrift》1991,33(3):305-316
In the situation of several 2 × 2 tables the asymptotic relative efficiencies of certain jackknife estimators of a common odds ratio are investigated in the case that the number of tables is fixed while the sample sizes within each table tend to infinity. The estimators show very good results over a wide range of parameters. Some situations in which the estimators have low asymptotic relative efficiency are pointed out:. 相似文献
10.
The Proverbial Bourdieu: Habitus and the Politics of Representation in the Ethnography of Kabylia 总被引:2,自引:0,他引:2
Jane E. Goodman 《American anthropologist》2003,105(4):782-793
Since the 1970s, anthropologists have been centrally concerned with the relationship of ethnographic representation to political and historical context. Interestingly, the work of Pierre Bourdieu has largely escaped such contextualization, despite the significance of Bourdieu's ideas to anthropological theorizing. Today, many of Bourdieu's central concepts float free from the context out of which they arose—the Kabyle region of Algeria. This article addresses this omission by reading Bourdieu's early works against each other to reconstitute aspects of his methodology and fieldwork. Focusing on his choice to represent the Kabyles of his early work in prose, and those in his later work via proverbs, I suggest that key premises of Bourdieu's theory may not be supported by historical and ethnographic evidence. I consider how Bourdieu's position as a young social scientist grappling with ethnographic responsibilities in colonial wartime led him to privilege his interlocutors' accounts in some studies while expunging them from others. [Keywords: Bourdieu, represented speech, literacy, Algeria, Berbers] 相似文献