全文获取类型
收费全文 | 4403篇 |
免费 | 381篇 |
国内免费 | 1篇 |
出版年
2023年 | 22篇 |
2022年 | 69篇 |
2021年 | 107篇 |
2020年 | 58篇 |
2019年 | 103篇 |
2018年 | 96篇 |
2017年 | 95篇 |
2016年 | 148篇 |
2015年 | 244篇 |
2014年 | 252篇 |
2013年 | 290篇 |
2012年 | 368篇 |
2011年 | 369篇 |
2010年 | 208篇 |
2009年 | 193篇 |
2008年 | 261篇 |
2007年 | 281篇 |
2006年 | 236篇 |
2005年 | 223篇 |
2004年 | 169篇 |
2003年 | 206篇 |
2002年 | 179篇 |
2001年 | 44篇 |
2000年 | 23篇 |
1999年 | 40篇 |
1998年 | 46篇 |
1997年 | 32篇 |
1996年 | 26篇 |
1995年 | 23篇 |
1994年 | 29篇 |
1993年 | 30篇 |
1992年 | 24篇 |
1991年 | 19篇 |
1990年 | 17篇 |
1989年 | 14篇 |
1988年 | 19篇 |
1987年 | 13篇 |
1986年 | 17篇 |
1985年 | 24篇 |
1984年 | 13篇 |
1983年 | 10篇 |
1980年 | 8篇 |
1979年 | 8篇 |
1978年 | 8篇 |
1977年 | 11篇 |
1976年 | 9篇 |
1975年 | 12篇 |
1973年 | 10篇 |
1971年 | 12篇 |
1967年 | 10篇 |
排序方式: 共有4785条查询结果,搜索用时 15 毫秒
101.
Joshua M. Plotnik Jennifer J. Pokorny Titiporn Keratimanochaya Christine Webb Hana F. Beronja Alice Hennessy James Hill Virginia J. Hill Rebecca Kiss Caitlin Maguire Beckett L. Melville Violet M. B. Morrison Dannah Seecoomar Benjamin Singer Jehona Ukehaxhaj Sophia K. Vlahakis Dora Ylli Nicola S. Clayton John Roberts Emilie L. Fure Alicia P. Duchatelier David Getz 《PloS one》2013,8(4)
Recent research suggests that domesticated species – due to artificial selection by humans for specific, preferred behavioral traits – are better than wild animals at responding to visual cues given by humans about the location of hidden food. \Although this seems to be supported by studies on a range of domesticated (including dogs, goats and horses) and wild (including wolves and chimpanzees) animals, there is also evidence that exposure to humans positively influences the ability of both wild and domesticated animals to follow these same cues. Here, we test the performance of Asian elephants (Elephas maximus) on an object choice task that provides them with visual-only cues given by humans about the location of hidden food. Captive elephants are interesting candidates for investigating how both domestication and human exposure may impact cue-following as they represent a non-domesticated species with almost constant human interaction. As a group, the elephants (n = 7) in our study were unable to follow pointing, body orientation or a combination of both as honest signals of food location. They were, however, able to follow vocal commands with which they were already familiar in a novel context, suggesting the elephants are able to follow cues if they are sufficiently salient. Although the elephants’ inability to follow the visual cues provides partial support for the domestication hypothesis, an alternative explanation is that elephants may rely more heavily on other sensory modalities, specifically olfaction and audition. Further research will be needed to rule out this alternative explanation. 相似文献
102.
Aurélie Bedel Jean- Max Pasquet éric Lippert Miguel Taillepierre Valérie Lagarde Sandrine Dabernat Pierre Dubus Lucie Charaf Fran?ois Beliveau Hubert de Verneuil Emmanuel Richard Fran?ois-Xavier Mahon Fran?ois Moreau-Gaudry 《PloS one》2013,8(8)
Chronic myeloid leukemia disease (CML) found effective therapy by treating patients with tyrosine kinase inhibitors (TKI), which suppress the BCR-ABL1 oncogene activity. However, the majority of patients achieving remission with TKI still have molecular evidences of disease persistence. Various mechanisms have been proposed to explain the disease persistence and recurrence. One of the hypotheses is that the primitive leukemic stem cells (LSCs) can survive in the presence of TKI. Understanding the mechanisms leading to TKI resistance of the LSCs in CML is a critical issue but is limited by availability of cells from patients. We generated induced pluripotent stem cells (iPSCs) derived from CD34+ blood cells isolated from CML patients (CML-iPSCs) as a model for studying LSCs survival in the presence of TKI and the mechanisms supporting TKI resistance. Interestingly, CML-iPSCs resisted to TKI treatment and their survival did not depend on BCR-ABL1, as for primitive LSCs. Induction of hematopoietic differentiation of CML-iPSC clones was reduced compared to normal clones. Hematopoietic progenitors obtained from iPSCs partially recovered TKI sensitivity. Notably, different CML-iPSCs obtained from the same CML patients were heterogeneous, in terms of BCR-ABL1 level and proliferation. Thus, several clones of CML-iPSCs are a powerful model to decipher all the mechanisms leading to LSC survival following TKI therapy and are a promising tool for testing new therapeutic agents. 相似文献
103.
Mathilde Chipaux Laurent Vercueil Anna Kaminska Séverine Mahon Stéphane Charpier 《PloS one》2013,8(3)
Absence seizures are caused by brief periods of abnormal synchronized oscillations in the thalamocortical loops, resulting in widespread spike-and-wave discharges (SWDs) in the electroencephalogram (EEG). SWDs are concomitant with a complete or partial impairment of consciousness, notably expressed by an interruption of ongoing behaviour together with a lack of conscious perception of external stimuli. It is largely considered that the paroxysmal synchronizations during the epileptic episode transiently render the thalamocortical system incapable of transmitting primary sensory information to the cortex. Here, we examined in young patients and in the Genetic Absence Epilepsy Rats from Strasbourg (GAERS), a well-established genetic model of absence epilepsy, how sensory inputs are processed in the related cortical areas during SWDs. In epileptic patients, visual event-related potentials (ERPs) were still present in the occipital EEG when the stimuli were delivered during seizures, with a significant increase in amplitude compared to interictal periods and a decrease in latency compared to that measured from non-epileptic subjects. Using simultaneous in vivo EEG and intracellular recordings from the primary somatosensory cortex of GAERS and non-epileptic rats, we found that ERPs and firing responses of related pyramidal neurons to whisker deflection were not significantly modified during SWDs. However, the intracellular subthreshold synaptic responses in somatosensory cortical neurons during seizures had larger amplitude compared to quiescent situations. These convergent findings from human patients and a rodent genetic model show the persistence of cortical responses to sensory stimulations during SWDs, indicating that the brain can still process external stimuli during absence seizures. They also demonstrate that the disruption of conscious perception during absences is not due to an obliteration of information transfer in the thalamocortical system. The possible mechanisms rendering the cortical operation ineffective for conscious perception are discussed, but their definite elucidation will require further investigations. 相似文献
104.
105.
Tafadzwa Tichagwa Nicola Pegg Hilton G. T. Ndagurwa Colum Zhuwau 《African Journal of Ecology》2020,58(4):766-777
Activity periods and diurnal behaviour of southern white rhino (Ceratotherium simum simum) were studied in Matobo National Park, Zimbabwe, from August 2016 to July 2017 using camera trapping and focal group sampling, respectively. Camera trap data showed that diurnal and nocturnal movements of white rhino varied significantly with moon phase, with more frequent nocturnal photographic captures during full- and third-quarter moon phases than during new and crescent moon phases. Permutational MANOVA and canonical correspondence analysis of focal group observation data were used to test the effects of season, time of day, habitat type, distance to roads, moon phase, presence/absence of other mammals, age/sex category, individual identity and herd composition on daytime behaviour. Weather conditions accounted for the majority of variation in rhino behaviour, with more time spent feeding during cloudy and rainy weather than sunny weather. Time of day and moon phase also accounted for high variation in behaviour, followed by habitat attributes and age/sex category. Variance partitioning by sets of explanatory variables showed that weather conditions had the greatest explanatory power in the variation of rhino behaviour, followed by temporal attributes, habitat attributes and age/sex category. Our findings provide insights for white rhino population management strategies aimed at increasing the effectiveness of security patrols, minimising disturbance and improving sightings for tourists. 相似文献
106.
107.
Calabrò Marco Mandelli Laura Crisafulli Concetta Porcelli Stefano Albani Diego Politis Antonis Papadimitriou George N. Di Nicola Marco Janiri Luigi Colombo Roberto Martinotti Giovanni Bellomo Antonello Vieta Eduard Bonassi Stefano Frustaci Alessandra Ducci Giuseppe Landi Stefano Boccia Stefania Serretti Alessandro 《Molecular biology reports》2020,47(1):191-200
Molecular Biology Reports - Serotoninergic system is one of the most important neurotransmission systems investigated in the field of psychiatry. Extensive evidence reveals how alterations of this... 相似文献
108.
109.
Nicola Maruotti Addolorata Corrado Cinzia Rotondo Francesco Paolo Cantatore 《Journal of cellular physiology》2020,235(3):1915-1920
Janus kinases (JAKs) play a pleiotropic role in several important physiological processes, such as cell maturation, cell proliferation, and cell death, via providing transmission signals from several molecules, such as cytokines, interferons, hormones, and growth factors, to the nucleus. Bone physiology and remodeling are markedly influenced by proinflammatory cytokines. Among them, interleukin-1 (IL-1) and IL-6 are considered potent stimulator of bone resorption. Several cytokine receptors, such as IL-6 receptors, are characterized by tyrosine kinases of the JAK family associated with their intracellular domains. There is an emerging interest in the effects of JAKs inhibition on the cells involved in bone remodeling. JAK inhibitors represent a new class of molecules involved in the therapy of numerous immune-mediated inflammatory diseases. In this review, we want to focus on the role of JAKs inhibitors on bone remodeling and on RANKL-RANK-OPG signal and inflammatory cytokines which are involved in the regulation of bone cells, such as osteoblasts and osteoclasts. 相似文献
110.
Head and neck cancer (HNC) is the six most common malignancy worldwide leading to more than 350,000 deaths annually. Despite recent advances in treatment modalities for these patients, there has been only a slight improvement of prognosis. As cancer stem cells (CSCs) have been implicated in tumor cell survival, progression, and response to therapy, the identification of this tumor subpopulation would have important therapeutic and prognostic implications. In this structured appraisal of the literature, Embase, PubMed, and Ovid were searched for publications that investigated CSC markers of HNC in humans. The search was conducted under the PRISMA guidelines with clear inclusion and exclusion criteria for articles published in the last two decades. The review process resulted in the identification of some key CSC-associated molecules such as CD44, ALDH1, CD133, Oct3/4, Nanog, and Sox2, although a single common CSC sorting marker could not be found. These biomarkers were identified in a range of HNCs but the most common one was squamous cell carcinoma (SCC), predominantly oral SCC. Patient cohorts were of variable size (3–195 individuals) and the most common technique used for detection was immunohistochemistry. Some of the molecules were associated with poor prognosis and may be able to inform the choice of appropriate treatment for these patients. 相似文献