全文获取类型
收费全文 | 7121篇 |
免费 | 623篇 |
国内免费 | 1篇 |
出版年
2024年 | 12篇 |
2023年 | 33篇 |
2022年 | 96篇 |
2021年 | 204篇 |
2020年 | 94篇 |
2019年 | 118篇 |
2018年 | 158篇 |
2017年 | 133篇 |
2016年 | 239篇 |
2015年 | 460篇 |
2014年 | 488篇 |
2013年 | 475篇 |
2012年 | 661篇 |
2011年 | 634篇 |
2010年 | 359篇 |
2009年 | 303篇 |
2008年 | 481篇 |
2007年 | 446篇 |
2006年 | 400篇 |
2005年 | 371篇 |
2004年 | 334篇 |
2003年 | 351篇 |
2002年 | 287篇 |
2001年 | 52篇 |
2000年 | 39篇 |
1999年 | 78篇 |
1998年 | 69篇 |
1997年 | 47篇 |
1996年 | 41篇 |
1995年 | 35篇 |
1994年 | 23篇 |
1993年 | 33篇 |
1992年 | 27篇 |
1991年 | 17篇 |
1990年 | 22篇 |
1989年 | 11篇 |
1988年 | 11篇 |
1987年 | 16篇 |
1986年 | 9篇 |
1985年 | 12篇 |
1984年 | 8篇 |
1983年 | 4篇 |
1982年 | 4篇 |
1981年 | 8篇 |
1980年 | 8篇 |
1978年 | 5篇 |
1977年 | 6篇 |
1975年 | 4篇 |
1974年 | 4篇 |
1971年 | 2篇 |
排序方式: 共有7745条查询结果,搜索用时 31 毫秒
201.
Mark Pennington Aleksandra Gentry-Maharaj Chloe Karpinskyj Alec Miners Julie Taylor Ranjit Manchanda Rema Iyer Michelle Griffin Andy Ryan Ian Jacobs Usha Menon Rosa Legood 《PloS one》2016,11(11)
BackgroundThere is limited evidence on the costs of Endometrial Cancer (EC) by stage of disease. We estimated the long-term secondary care costs of EC according to stage at diagnosis in an English population-based cohort.MethodsWomen participating in UKCTOCS and diagnosed with EC following enrolment (2001–2005) and prior to 31st Dec 2009 were identified to have EC through multiple sources. Survival was calculated through data linkage to death registry. Costs estimates were derived from hospital records accessed from Hospital Episode Statistics (HES) with additional patient level covariates derived from case notes and patient questionnaires. Missing and censored data was imputed using Multiple Imputation. Regression analysis of cost and survival was undertaken.Results491 of 641 women with EC were included. Five year total costs were strongly dependent on stage, ranging from £9,475 (diagnosis at stage IA/IB) to £26,080 (diagnosis at stage III). Stage, grade and BMI were the strongest predictors of costs. The majority of costs for stage I/II EC were incurred in the first six months after diagnosis while for stage III / IV considerable costs accrued after the first six months.ConclusionsIn addition to survival advantages, there are significant cost savings if patients with EC are detected earlier. 相似文献
202.
Hsin-I Tong Wen Kang Philip M. C. Davy Yingli Shi Si Sun Richard C. Allsopp Yuanan Lu 《PloS one》2016,11(4)
The ability of monocytes and monocyte-derived macrophages (MDM) to travel towards chemotactic gradient, traverse tissue barriers, and accumulate precisely at diseased sites makes them attractive candidates as drug carriers and therapeutic gene delivery vehicles targeting the brain, where treatments are often hampered by the blockade of the blood brain barrier (BBB). This study was designed to fully establish an optimized cell-based delivery system using monocytes and MDM, by evaluating their homing efficiency, engraftment potential, as well as carriage and delivery ability to transport nano-scaled particles and exogenous genes into the brain, following the non-invasive intravenous (IV) cell adoptive transfer in an acute neuroinflammation mouse model induced by intracranial injection of Escherichia coli lipopolysaccharides. We demonstrated that freshly isolated monocytes had superior inflamed-brain homing ability over MDM cultured in the presence of macrophage colony stimulating factor. In addition, brain trafficking of IV infused monocytes was positively correlated with the number of adoptive transferred cells, and could be further enhanced by transient disruption of the BBB with IV administration of Mannitol, Bradykinin or Serotonin right before cell infusion. A small portion of transmigrated cells was detected to differentiate into IBA-1 positive cells with microglia morphology in the brain. Finally, with the use of superparamagnetic iron oxide nanoparticles SHP30, the ability of nanoscale agent-carriage monocytes to enter the inflamed brain region was validated. In addition, lentiviral vector DHIV-101 was used to introduce green fluorescent protein (GFP) gene into monocytes, and the exogenous GFP gene was detected in the brain at 48 hours following IV infusion of the transduced monocytes. All together, our study has set up the optimized conditions for the more-in-depth tests and development of monocyte-mediated delivery, and our data supported the notion to use monocytes as a non-invasive cell-based delivery system for the brain. 相似文献
203.
Karen L. Cheney Andrew White I. Wayan Mudianta Anne E. Winters Michelle Quezada Robert J. Capon Ernesto Mollo Mary J. Garson 《PloS one》2016,11(1)
Natural products play an invaluable role as a starting point in the drug discovery process, and plants and animals use many interesting biologically active natural products as a chemical defense mechanism against predators. Among marine organisms, many nudibranch gastropods are known to derive defensive metabolites from the sponges they eat. Here we investigated the putative sequestration of the toxic compound latrunculin A—a 16-membered macrolide that prevents actin polymerization within cellular processes—which has been identified from sponge sources, by five closely related nudibranch molluscs of the genus Chromodoris. Only latrunculin A was present in the rim of the mantle of these species, where storage reservoirs containing secondary metabolites are located, whilst a variety of secondary metabolites were found in their viscera. The species studied thus selectively accumulate latrunculin A in the part of the mantle that is more exposed to potential predators. This study also demonstrates that latrunculin-containing sponges are not their sole food source. Latrunculin A was found to be several times more potent than other compounds present in these species of nudibranchs when tested by in vitro and in vivo toxicity assays. Anti-feedant assays also indicated that latrunculin A was unpalatable to rock pool shrimps, in a dose-dependent manner. These findings led us to propose that this group of nudibranchs has evolved means both to protect themselves from the toxicity of latrunculin A, and to accumulate this compound in the mantle rim for defensive purposes. The precise mechanism by which the nudibranchs sequester such a potent compound from sponges without disrupting their own key physiological processes is unclear, but this work paves the way for future studies in this direction. Finally, the possible occurrence of both visual and chemosensory Müllerian mimicry in the studied species is discussed. 相似文献
204.
205.
206.
207.
Jessica?V.?BryantEmail author Aurélien?Brulé Michelle?H.?G.?Wong Xiaojiang?Hong Zhaoli?Zhou Wentao?Han Timothy?E.?Jeffree Samuel?T.?Turvey 《International journal of primatology》2016,37(4-5):534-547
Targeted management actions informed by robust data are needed to conserve species of extreme rarity, and assessing the effectiveness of different field methods for detection and monitoring of such species is a conservation priority. Gibbons are typically detected by their daily song through passive listening surveys, but lone gibbon individuals and low-density populations are less likely to sing, making detection difficult or impossible using standard survey techniques. Call playback represents an alternative potential method for detecting gibbon presence, but there has been no empirical evaluation of the usefulness of this method in the field. We investigated the efficacy of call playback as a survey method for detecting previously unconfirmed or unknown individuals of the Critically Endangered Hainan gibbon (Nomascus hainanus), the world’s rarest primate, in patches of good-quality forest outside the current home ranges of the three known Hainan gibbon social groups in Bawangling National Nature Reserve, Hainan, China. Call playback led to detection of a male-only call likely to have been made by a solitary male, and a previously unknown social group comprising an adult male, adult female, and an infant, increasing the number of known breeding females in the global Hainan gibbon population from five to six. Call playback therefore represents an effective tool for improved monitoring of Hainan gibbons, as well as other gibbon populations; however, it is a moderately disruptive survey technique, and should be employed sparingly, in key locations, and for short periods of time only when attempting to detect gibbon presence. 相似文献
208.
209.
210.
Rosana S Lopes Marcelo M Cardoso Arthur O Sampaio Mario Santos BarbosaJr Celice C Souza Michelle C da Silva Elane Magno N Ferreira Marco Aurelio M Freire Rafael Rodrigues Lima Walace Gomes-Leal 《Journal of biosciences》2016,41(3):381-394
Neuroblasts from the subventricular zone (SVZ) migrate to striatum following stroke, but most of them die in the ischaemic milieu and this can be related to exacerbated microglial activation. Here, we explored the effects of the non-steroidal anti-inflammatory indomethacin on microglial activation, neuronal preservation and neuroblast migration following experimental striatal stroke in adult rats. Animals were submitted to endothelin-1 (ET-1)-induced focal striatal ischaemia and were treated with indomethacin or sterile saline (i.p.) for 7 days, being perfused after 8 or 14 days. Immunohistochemistry was performed to assess neuronal loss (anti-NeuN), microglial activation (anti-Iba1, ED1) and migrating neuroblasts (anti-DCX) by counting NeuN, ED1 and DCX-positive cells in the ischaemic striatum or SVZ. Indomethacin treatment reduced microglia activation and the number of ED1+ cells in both 8 and 14 days post injury as compared with controls. There was an increase in the number of DCX+ cells in both SVZ and striatum at the same survival times. Moreover, there was a decrease in the number of NeuN+ cells in indomethacin-treated animals as compared with the control group at 8 days but not after 14 days post injury. Our results suggest that indomethacin treatment modulates microglia activation, contributing to increased neuroblast proliferation in the SVZ and migration to the ischaemic striatum following stroke. 相似文献