全文获取类型
收费全文 | 7925篇 |
免费 | 592篇 |
国内免费 | 1篇 |
出版年
2023年 | 42篇 |
2022年 | 119篇 |
2021年 | 203篇 |
2020年 | 126篇 |
2019年 | 138篇 |
2018年 | 174篇 |
2017年 | 136篇 |
2016年 | 233篇 |
2015年 | 429篇 |
2014年 | 461篇 |
2013年 | 540篇 |
2012年 | 695篇 |
2011年 | 627篇 |
2010年 | 410篇 |
2009年 | 383篇 |
2008年 | 511篇 |
2007年 | 453篇 |
2006年 | 403篇 |
2005年 | 339篇 |
2004年 | 318篇 |
2003年 | 325篇 |
2002年 | 295篇 |
2001年 | 79篇 |
2000年 | 75篇 |
1999年 | 93篇 |
1998年 | 67篇 |
1997年 | 63篇 |
1996年 | 44篇 |
1995年 | 47篇 |
1994年 | 47篇 |
1993年 | 42篇 |
1992年 | 56篇 |
1991年 | 31篇 |
1990年 | 31篇 |
1989年 | 42篇 |
1988年 | 50篇 |
1987年 | 30篇 |
1986年 | 33篇 |
1985年 | 30篇 |
1984年 | 31篇 |
1983年 | 21篇 |
1982年 | 22篇 |
1981年 | 20篇 |
1979年 | 22篇 |
1978年 | 18篇 |
1975年 | 11篇 |
1974年 | 17篇 |
1973年 | 15篇 |
1970年 | 16篇 |
1969年 | 11篇 |
排序方式: 共有8518条查询结果,搜索用时 87 毫秒
1.
Ouenzar Bouchra Hartmann Caroline Rode Andre Benslimane Abdelali 《Plant Molecular Biology Reporter》1998,16(3):263-269
We have developed a new mini-procedure for isolation of total cellular DNA from date palm (Phoenix dactylifera L.). The procedure, which does not use liquid nitrogen, has proved useful due to temporary disruptions in supplies of liquid nitrogen that occur in countries where date palm trees are cultivated. DNA suitable for RFLP and PCR analyses is obtained. 相似文献
2.
3.
Elisabeth Hansson Ingemar Jacobson Richard Venema Åke Sellström 《Journal of neurochemistry》1980,34(3):569-573
Abstract: The lipophilic cation [3 H]triphenylrnethylphosphonium bromide ([3 H]TPMP+ ) was investigated as a measure of the membrane potential of synaptosomes. Conditions under which [3 H]TPMP+ achieved an equilibrium distribution were tested. The toxicity of TPMP has been studied relative to its inhibitory effects on [3 H]y-aminobutyric acid ([3 H]GABA) transport. In some experiments the distribution of 86 RbZ+ and [3 H]TPMP+ was changed upon incubation in the presence of elevated levels of K+ , ouabain, or KCN, or at 0°C in a way that would be expected from the membrane potential. In normal incubation conditions a membrane potential of ∼−60 mv was calculated. 相似文献
4.
Rafael Ricci-Azevedo Aline Ferreira Oliveira Marina C. A. V. Conrado Fernanda Caroline Carvalho Maria Cristina Roque-Barreira 《PLoS neglected tropical diseases》2016,10(4)
ArtinM, a D-mannose binding lectin from Artocarpus heterophyllus, has immunomodulatory activities through its interaction with N-glycans of immune cells, culminating with the establishment of T helper type 1 (Th1) immunity. This interaction protects mice against intracellular pathogens, including Leishmania major and Leishmania amazonensis. ArtinM induces neutrophils activation, which is known to account for both resistance to pathogens and host tissue injury. Although exacerbated inflammation was not observed in ArtinM-treated animals, assessment of neutrophil responses to ArtinM is required to envisage its possible application to design a novel immunomodulatory agent based on carbohydrate recognition. Herein, we focus on the mechanisms through which neutrophils contribute to ArtinM-induced protection against Leishmania, without exacerbating inflammation. For this purpose, human neutrophils treated with ArtinM and infected with Leishmania major were analyzed together with untreated and uninfected controls, based on their ability to eliminate the parasite, release cytokines, degranulate, produce reactive oxygen species (ROS), form neutrophil extracellular traps (NETs) and change life span. We demonstrate that ArtinM-stimulated neutrophils enhanced L. major clearance and at least duplicated tumor necrosis factor (TNF) and interleukin-1beta (IL-1β) release; otherwise, transforming growth factor-beta (TGF-β) production was reduced by half. Furthermore, ROS production and cell degranulation were augmented. The life span of ArtinM-stimulated neutrophils decreased and they did not form NETs when infected with L. major. We postulate that the enhanced leishmanicidal ability of ArtinM-stimulated neutrophils is due to augmented release of inflammatory cytokines, ROS production, and cell degranulation, whereas host tissue integrity is favored by their shortened life span and the absence of NET formation. Our results reinforce the idea that ArtinM may be considered an appropriate molecular template for the construction of an efficient anti-infective agent. 相似文献
5.
Anthony J. Hesketh Caroline Maloney Christopher A. Behr Morris C. Edelman Richard D. Glick Yousef Al-Abed Marc Symons Samuel Z. Soffer Bettie M. Steinberg 《PloS one》2015,10(12)
Metastatic Ewing Sarcoma carries a poor prognosis, and novel therapeutics to prevent and treat metastatic disease are greatly needed. Recent evidence demonstrates that tumor-associated macrophages in Ewing Sarcoma are associated with more advanced disease. While some macrophage phenotypes (M1) exhibit anti-tumor activity, distinct phenotypes (M2) may contribute to malignant progression and metastasis. In this study, we show that M2 macrophages promote Ewing Sarcoma invasion and extravasation, pointing to a potential target of anti-metastatic therapy. CNI-1493 is a selective inhibitor of macrophage function and has shown to be safe in clinical trials as an anti-inflammatory agent. In a xenograft mouse model of metastatic Ewing Sarcoma, CNI-1493 treatment dramatically reduces metastatic tumor burden. Furthermore, metastases in treated animals have a less invasive morphology. We show in vitro that CNI-1493 decreases M2-stimulated Ewing Sarcoma tumor cell invasion and extravasation, offering a functional mechanism through which CNI-1493 attenuates metastasis. These data indicate that CNI-1493 may be a safe and effective adjuvant agent for the prevention and treatment of metastatic Ewing Sarcoma. 相似文献
6.
Jill S. Marty James P. Higham Elizabeth L. Gadsby Caroline Ross 《International journal of primatology》2009,30(6):807-823
Sexual selection has driven the evolution and elaboration of a wide variety of displays and ornaments in male nonhuman primates,
including capes, cheek flanges, and sexual coloration. Among the most sexually dimorphic of all primates is the drill (Mandrillus leucophaeus), the males of which can be 3 times the mass of females, possess large canines, and exhibit extremely bright sexual skin
coloration. However, the function of male coloration in this species has never been examined. Here, we present data on male
color (measured objectively using digital photography), dominance rank, measures of male-female association, and key sexual
behaviors, of adult male drills (n = 17) living in four semi free-ranging enclosures at the Drill Rehabilitation and Breeding Center in Nigeria. We test the
hypothesis that male coloration is a badge of status, indicating dominance rank, and the hypothesis that male coloration attracts
females. We found that male coloration did indicate rank, and that high ranking, strongly colored males were more likely to
associate with adult females, and more specifically with fully tumescent females. These males also engaged in more sexual
activity. However, measures of male-female association and sexual behaviors were not related to male color once rank had been
taken into consideration; i.e., for males of a given rank, females did not prefer those that were more colorful. We discuss
the results in light of what is known about the wild drill social system, in which unfamiliar individuals may come together
in “supergroups,” and in which quality indicators of competitive ability may be particularly important. 相似文献
7.
Vincent Anquetil Caroline Le Sommer Agn��s M��reau Sandra Hamon Hubert Lerivray Serge Hardy 《The Journal of biological chemistry》2009,284(47):32370-32383
Alternative splicing of 3′-terminal exons plays a critical role in gene expression by producing mRNA with distinct 3′-untranslated regions that regulate their fate and their expression. The Xenopus α-tropomyosin pre-mRNA possesses a composite internal/3′-terminal exon (exon 9A9′) that is differentially processed depending on the embryonic tissue. Exon 9A9′ is repressed in non-muscle tissue by the polypyrimidine tract binding protein, whereas it is selected as a 3′-terminal or internal exon in myotomal cells and adult striated muscles, respectively. We report here the identification of an intronic regulatory element, designated the upstream terminal exon enhancer (UTE), that is required for the specific usage of exon 9A9′ as a 3′-terminal exon in the myotome. We demonstrate that polypyrimidine tract binding protein prevents the activity of UTE in non-muscle cells, whereas a subclass of serine/arginine rich (SR) proteins promotes the selection of exon 9A9′ in a UTE-dependent way. Morpholino-targeted blocking of UTE in the embryo strongly reduced the inclusion of exon 9A9′ as a 3′-terminal exon in the endogenous mRNA, demonstrating the function of UTE under physiological circumstances. This strategy allowed us to reveal a splicing pathway that generates a mRNA with no in frame stop codon and whose steady-state level is translation-dependent. This result suggests that a non-stop decay mechanism participates in the strict control of the 3′-end processing of the α-tropomyosin pre-mRNA. 相似文献
8.
Alba Luengo Zhaoqi Li Dan Y. Gui Lucas B. Sullivan Maria Zagorulya Brian T. Do Raphael Ferreira Adi Naamati Ahmed Ali Caroline A. Lewis Craig J. Thomas Stefani Spranger Nicholas J. Matheson Matthew G. Vander Heiden 《Molecular cell》2021,81(4):691-707.e6
- Download : Download high-res image (172KB)
- Download : Download full-size image
9.
10.
Metabolism of palmitate in cultured rat Sertoli cells 总被引:1,自引:0,他引:1
Isolated rat Sertoli cells were incubated in the presence of [1-14C]palmitate at a cell concentration of 1.54 +/- 0.31 mg protein/flask (n = 7). The oxidation of palmitate was concentration dependent and maximal oxidation was obtained at 0.35 mM-palmitate. At a saturating concentration of palmitate the oxidation was linear for at least 6 h. About 65% of the total amount of palmitate oxidized during 5 h at 0.52 mM-palmitate (109 +/- 44 nmol/flask, n = 5) was recovered as CO2 and the rest as acid-soluble compounds. Almost all radioactive acid-soluble compounds which were secreted by the Sertoli cells were shown to be 3-hydroxybutyrate and acetoacetate. The palmitate recovery in cellular lipids and triacylglycerols was 9.4 +/- 5.1 nmol/flask (n = 5) and 3.5 +/- 2.8 nmol/flask (n = 5) respectively. Addition of glucose had no significant effect on palmitate oxidation but caused a 9-fold increase in esterification of palmitate into triacylglycerols. We conclude that cultured rat Sertoli cells can oxidize palmitate to CO2 and ketone bodies and that fatty acids appear to be a major energy substrate for these cells. 相似文献