全文获取类型
收费全文 | 10423篇 |
免费 | 681篇 |
国内免费 | 1篇 |
出版年
2023年 | 68篇 |
2022年 | 62篇 |
2021年 | 233篇 |
2020年 | 181篇 |
2019年 | 210篇 |
2018年 | 280篇 |
2017年 | 213篇 |
2016年 | 345篇 |
2015年 | 531篇 |
2014年 | 539篇 |
2013年 | 758篇 |
2012年 | 843篇 |
2011年 | 804篇 |
2010年 | 492篇 |
2009年 | 480篇 |
2008年 | 611篇 |
2007年 | 588篇 |
2006年 | 606篇 |
2005年 | 524篇 |
2004年 | 509篇 |
2003年 | 447篇 |
2002年 | 444篇 |
2001年 | 83篇 |
2000年 | 63篇 |
1999年 | 83篇 |
1998年 | 88篇 |
1997年 | 82篇 |
1996年 | 50篇 |
1995年 | 77篇 |
1994年 | 64篇 |
1993年 | 67篇 |
1992年 | 50篇 |
1991年 | 47篇 |
1990年 | 48篇 |
1989年 | 43篇 |
1988年 | 41篇 |
1987年 | 31篇 |
1986年 | 28篇 |
1985年 | 24篇 |
1984年 | 41篇 |
1983年 | 27篇 |
1982年 | 40篇 |
1981年 | 37篇 |
1980年 | 37篇 |
1979年 | 24篇 |
1978年 | 22篇 |
1977年 | 17篇 |
1976年 | 18篇 |
1975年 | 13篇 |
1974年 | 13篇 |
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
1.
2.
Phylogeography and population differentiation in the Psittacanthus calyculatus (Loranthaceae) mistletoe: a complex scenario of climate–volcanism interaction along the Trans‐Mexican Volcanic Belt 下载免费PDF全文
3.
Autonomic Adaption to Clinical Simulation in Psychology Students: Teaching Applications 总被引:1,自引:0,他引:1
Vicente Javier Clemente-Suárez Ana Isabel Beltrán-Velasco Alberto Bellido-Esteban Pablo Ruisoto-Palomera 《Applied psychophysiology and biofeedback》2018,43(3):239-245
Simulation is used to facilitate new learning in a variety of situations. One application of simulation could be to help therapists gain therapeutic skills prior to seeing clients. This particular study was interested in measuring changes in stress response by looking at subjective and objective measures of distress (as measured by SUDS, HR, and HRV) over three sessions of simulated therapy. 16 second year psychology students participated in three sessions, and had their HR and HRV measured by Polar watches. Over the three sessions, there was a decrease in perceived distress, as measured by SUDS ratings. During and between sessions, there was inconclusive change in physiological parameters. 相似文献
4.
Sonia Tarazona Pedro Furió-Tarí David Turrà Antonio Di Pietro María José Nueda Alberto Ferrer Ana Conesa 《Nucleic acids research》2015,43(21):e140
As the use of RNA-seq has popularized, there is an increasing consciousness of the importance of experimental design, bias removal, accurate quantification and control of false positives for proper data analysis. We introduce the NOISeq R-package for quality control and analysis of count data. We show how the available diagnostic tools can be used to monitor quality issues, make pre-processing decisions and improve analysis. We demonstrate that the non-parametric NOISeqBIO efficiently controls false discoveries in experiments with biological replication and outperforms state-of-the-art methods. NOISeq is a comprehensive resource that meets current needs for robust data-aware analysis of RNA-seq differential expression. 相似文献
5.
Dora E. Vega-Salas Julio A. San Martino Pedro J.I. Salas Alberto Baldi 《Differentiation; research in biological diversity》1993,54(3):131-141
Abstract. We have previously shown that an integral plasma membrane glycoprotein (AP2) is highly polarized to the apical domain in confluent Madin-Darby canine kidney (MDCK) epithelial cells. However, when the monolayers are prevented from forming intercellular contacts, approximately 60% of the AP2 cellular content is stored in the intracellular vacuolar apical compartment (VAC). In the current work we found that AP2 was present in the non-tumorigenic human mammary epithelial cell line MCF-10A. in the breast carcinoma cell lines MCF-7 and T47D, and in breast ductal carcinomas in vivo. By radioimmunoassay, an intracellular Compartment of AP2 was identified in the mammary cell lines in culture. In MCF-10A, this compartment behaved as in MDCK cells; namely it was observed only when the cells cannot form cell-cell contacts. However, in the carcinoma cell lines MCF-7 and T47D, a significant AP2 intracellular compartment was observed also under conditions permissive for the formation of intercellular contacts. These results were confirmed by immunofluorescence and immunoelectron microscopy experiments that showed VACs in MCF-7 and T47D, even in cells with extensive intercellular contacts. In MCF-7 cells, the addition of serum caused a partial decrease of the AP2 intracellular compartment. The exocytosis of VACs occurred towards the center of multi-cellular groups, forming intercellular lumens, similar to those transiently observed in MDCK cells and to structures described by others during embryo development. Altogether, these results suggest that VAC exocytosis is controlled by cell-cell contact signalling, which may be defective in carcinoma cells. 相似文献
6.
7.
Marine amoebae from waters of northwest Spain, with comments on a potentially pathogenic euryhaline species 总被引:1,自引:0,他引:1
M C Arias Fernandez E Paniagua Crespo M Marti Mallen M P Penas Ares M L Casro Casas 《The Journal of protozoology》1989,36(3):239-241
Of 17 species of free-living amoebae identified in various samples of salt water, only 1, Acanthamoeba polyphaga, is known to be a potential pathogen. While no deaths occurred when laboratory animals were inoculated with A. polyphaga to test for pathogenicity, the protozoa were present in the brain, liver and lungs of some but not all of the animals. 相似文献
8.
Joachim Langeneck Fabio Scarpa Ferruccio Maltagliati Daria Sanna Michele Barbieri Piero Cossu Barbara Mikac Marco Curini Galletti Alberto Castelli Marco Casu 《Journal of Zoological Systematics and Evolutionary Research》2020,58(1):66-78
The cryptic diversity in the polychaete Syllis gracilis Grube, 1840, in the Mediterranean Sea was examined with an integrative morpho-molecular approach. Individuals of S. gracilis were collected at eleven Mediterranean localities to provide an insight into the role of brackish environments in inducing cryptic speciation. The examination of morphological features combined with a molecular genetic analysis based on a partial sequence of the 16S rRNA gene highlighted discrepancies between morphological and molecular diversity. Morphological data allowed to identify a morphotype with short appendages occurring in coralline algae communities and another one with long appendages observed in brackish-water environments and Sabellaria reefs. Multivariate analyses showed that sampling localities were the greatest source of morphological divergence, suggesting that phenotypic plasticity may play a role in local adaptations of S. gracilis populations. Molecular data showed the occurrence of four divergent lineages not corresponding to morphological clusters. Different species delimitation tests gave conflicting results, retrieving, however, at least four separated entities. Some lineages occurred in sympatry and were equally distributed in marine and brackish-water environments, excluding a biogeographic or ecological explanation of the observed pattern and suggesting instead ancient separation between lineages and secondary contact. The co-occurrence of different lineages hindered the identification of the lineage corresponding to S. gracilis sensu stricto. The discrepancy between morphological and molecular diversity suggests that different environmental and biogeographic features may interact in a complex and unpredictable way in shaping diversity patterns. An integrative approach is needed to provide a satisfactory insight on evolutionary processes in marine invertebrates. 相似文献
9.
Olatz Arteaga Miren Revuelta Leyre Urigüen Antonia álvarez Haizea Montalvo Enrique Hilario 《PloS one》2015,10(11)
Despite advances in neonatal care, hypoxic-ischemic brain injury is still a serious clinical problem, which is responsible for many cases of perinatal mortality, cerebral palsy, motor impairment and cognitive deficits. Resveratrol, a natural polyphenol with important anti-oxidant and anti-inflammatory properties, is present in grapevines, peanuts and pomegranates. The aim of the present work was to evaluate the possible neuroprotective effect of resveratrol when administered before or immediately after a hypoxic-ischemic brain event in neonatal rats by analyzing brain damage, the mitochondrial status and long-term cognitive impairment. Our results indicate that pretreatment with resveratrol protects against brain damage, reducing infarct volume, preserving myelination and minimizing the astroglial reactive response. Moreover its neuroprotective effect was found to be long lasting, as behavioral outcomes were significantly improved at adulthood. We speculate that one of the mechanisms for this neuroprotection may be related to the maintenance of the mitochondrial inner membrane integrity and potential, and to the reduction of reactive oxygen species. Curiously, none of these protective features was observed when resveratrol was administered immediately after hypoxia-ischemia. 相似文献