首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   5303篇
  免费   493篇
  国内免费   329篇
耳鼻咽喉   31篇
儿科学   86篇
妇产科学   113篇
基础医学   696篇
口腔科学   118篇
临床医学   695篇
内科学   894篇
皮肤病学   80篇
神经病学   312篇
特种医学   182篇
外科学   694篇
综合类   743篇
现状与发展   2篇
一般理论   1篇
预防医学   273篇
眼科学   127篇
药学   495篇
  1篇
中国医学   201篇
肿瘤学   381篇
  2024年   12篇
  2023年   73篇
  2022年   84篇
  2021年   226篇
  2020年   181篇
  2019年   154篇
  2018年   200篇
  2017年   159篇
  2016年   166篇
  2015年   220篇
  2014年   275篇
  2013年   247篇
  2012年   399篇
  2011年   450篇
  2010年   243篇
  2009年   229篇
  2008年   290篇
  2007年   311篇
  2006年   256篇
  2005年   272篇
  2004年   207篇
  2003年   185篇
  2002年   144篇
  2001年   136篇
  2000年   136篇
  1999年   148篇
  1998年   92篇
  1997年   74篇
  1996年   75篇
  1995年   64篇
  1994年   51篇
  1993年   46篇
  1992年   52篇
  1991年   36篇
  1990年   39篇
  1989年   32篇
  1988年   23篇
  1987年   22篇
  1986年   23篇
  1985年   14篇
  1984年   14篇
  1983年   10篇
  1982年   6篇
  1981年   6篇
  1979年   10篇
  1973年   2篇
  1972年   4篇
  1971年   3篇
  1970年   6篇
  1969年   6篇
排序方式: 共有6125条查询结果,搜索用时 203 毫秒
121.
目的观察日达仙稀释液对化疗后口腔溃疡患者的治疗作用。方法选择住院化疗后并发口腔溃疡患者68名,随机分为治疗组及对照组,治疗组用日达仙液涂抹溃疡面,对照组用锡类散涂抹溃疡面,观察两组间口腔溃疡疗效的差异。结果治疗组患者平均溃疡治愈时间(4.87±0.96)d及平均疼痛指数(3.84±1.21)分均明显低于对照组,差异均有统计学意义(t分别=7.55、5.46,P均<0.05)。结论日达仙稀释液对患者化疗后并发的口腔溃疡有较好疗效。  相似文献   
122.
The acinus-mimicking microfluidic chip, which simulates the in vivo condition of the liver, was developed and reported in this paper. The gradient microenvironment of the liver acinus is replicated within this proposed microfluidic chip. The advantage of this acinus-mimicking chip is capable of adjusting the concentration gradient in a relatively short period of time at around 10 s. At the same instance the non-linear concentration gradient can be presented in the various zones within this microfluidic chip. The other advantage of this proposed design is in the convenience of allowing the direct injection of the cells into the chip. The environment within the chip is multi-welled and gel-free with high cell density. The multi-row pillar microstructure located at the entrance of the top and bottom flow channels is designed to be able to balance the pressure of the perfusion medium. Through this mechanism the shear stress experienced by the cultured cells can be minimized to reduce the potential damage flow from the perfusion process. (3)The fluorescence staining and the observations of the cell morphology verify the life and death of the cells. The shear stress experienced by the cells in the various zones within the chip can be effectively mapped. The serum glutamic oxaloacetic transaminase (SGOT) collected from the supernatants was used to determine the effects of the degassing process and the shear stress of the medium flow on the cultured cells.  相似文献   
123.
<正>人体解剖学作为医学专业必修课,在"互联网+"的潮流中面临巨大的挑战和机遇~([1])。为了突破以"教师"为中心的传统教学模式~([2]),我们开发了基于手机应用程序(application,APP)的人体解剖学课程,现就使用人体解剖学APP课程的教学实践进行总结。1人体解剖学APP课程教学准备1.1人体解剖学APP课程的设计方案人体解剖学APP课程可分为线上课程和线下课程,两  相似文献   
124.
125.
126.
This study sought to prepare a self-microemulsion drug delivery system containing zingerone (Z-SMEDDS) to improve the low oral bioavailability of zingerone and anti-tumor effect. Z-SMEDDS was characterized by particle size, zeta potential and encapsulation efficiency, while its pharmacokinetics and anti-tumor effects were also evaluated. Z-SMEDDS had stable physicochemical properties, including average particle size of 17.29 ± 0.07 nm, the zeta potential of -22.81 ± 0.29 mV, and the encapsulation efficiency of 97.96% ± 0.02%. In vitro release studies have shown the release of zingerone released by Z-SMEDDS was significantly higher than free zingerone in different release media. The relative oral bioavailability of Z-SMEDDS was 7.63 times compared with free drug. Meanwhile, the half inhibitory concentration (IC50)of Z-SMEDDS and free zingerone was 8.45 μg/mL and 13.30 μg/mL, respectively on HepG2. This study may provide a preliminary basis for further clinical research and application of Z-SMEDDS.  相似文献   
127.
ABSTRACT: BACKGROUND: : Using live imaging approach we have previously shown that microglia activation after stroke is characterized by marked and long-term induction of the Toll like Receptor 2 (TLR2) biophotonic signals. However, the role of TLR2 (and potentially other TLRs), beyond the acute innate immune response and an early neuroprotection against ischemic injury is not well understood. METHOD: S: The TLR2 -/- mice were subjected to transient middle cerebral artery occlusion (MCAO) followed by different reperfusion times. Analyses assessing microglial activation profile/innate immune response were performed using in situ hybridization, immunohistochemistry analysis, flow cytometry and inflammatory cytokine array. The effects of the TLR2 deficiency on the evolution of ischemic brain injury were analyzed using a cresyl violet staining of brain sections with appropriate lesion size estimation. RESULTS: : Here we report that TLR2 deficiency markedly affects post-stroke immune response resulting in delayed exacerbation of the ischemic injury. The temporal analysis of the microglia/macrophage activation profiles in TLR2 -/- mice and age-matched controls revealed reduced microglia/macrophage activation after stroke, reduced capacity of resident microglia to proliferate as well as decreased levels of MCP-1 and consequently lower levels of CD45high/CD11b+ expressing cells as shown by flow cytometry analysis. Importantly, although acute ischemic lesions (24-72hrs) were smaller in TLR2 -/- mice, the observed alterations in innate immune response were more pronounces at later time-points (at day 7) after initial stroke, which finally resulted in delayed exacerbation of ischemic lesion leading to larger chronic infarctions as compared to WT mice. Moreover, our results revealed that TLR2 deficiency is associated with significant decrease in the levels of neurotrophic/antiapoptotic factor IGF-1, expressed by microglia in the areas in- and around ischemic lesion. CONCLUSION: Altogether our results clearly suggest that optimal and timely microglial activation/innate immune response is needed to limit neuronal damage after stroke.  相似文献   
128.
Spatiotemporal regulation of signaling cascades is crucial for various biological pathways, under the control of a range of scaffolding proteins. The BNIP-2 and Cdc42GAP Homology (BCH) domain is a highly conserved module that targets small GTPases and their regulators. Proteins bearing BCH domains are key for driving cell elongation, retraction, membrane protrusion, and other aspects of active morphogenesis during cell migration, myoblast differentiation, and neuritogenesis. We previously showed that the BCH domain of p50RhoGAP (ARHGAP1) sequesters RhoA from inactivation by its adjacent GAP domain; however, the underlying molecular mechanism for RhoA inactivation by p50RhoGAP remains unknown. Here, we report the crystal structure of the BCH domain of p50RhoGAP Schizosaccharomyces pombe and model the human p50RhoGAP BCH domain to understand its regulatory function using in vitro and cell line studies. We show that the BCH domain adopts an intertwined dimeric structure with asymmetric monomers and harbors a unique RhoA-binding loop and a lipid-binding pocket that anchors prenylated RhoA. Interestingly, the β5-strand of the BCH domain is involved in an intermolecular β-sheet, which is crucial for inhibition of the adjacent GAP domain. A destabilizing mutation in the β5-strand triggers the release of the GAP domain from autoinhibition. This renders p50RhoGAP active, thereby leading to RhoA inactivation and increased self-association of p50RhoGAP molecules via their BCH domains. Our results offer key insight into the concerted spatiotemporal regulation of Rho activity by BCH domain–containing proteins.

Small GTPases are molecular switches that cycle between an active GTP-bound state and an inactive GDP-bound state and are primarily involved in cytoskeletal reorganization during cell motility, morphogenesis, and cytokinesis (1, 2). These small GTPases are tightly controlled by activators and inactivators, such as guanine nucleotide exchange factors (GEFs) and GTPase-activating proteins (GAPs), respectively (3, 4), which are multidomain proteins that are themselves regulated through their interactions with other proteins, lipids, secondary messengers, and/or by posttranslational modifications (57). Despite our understanding of the mechanisms of action of GTPases, GAPs, and GEFs, little is known about how they are further regulated by other cellular proteins in tightly controlled local environments.The BNIP-2 and Cdc42GAP Homology (BCH) domain has emerged as a highly conserved and versatile scaffold protein domain that targets small GTPases, their GEFs, and GAPs to carry out various cellular processes in a spatial, temporal, and kinetic manner (815). BCH domain–containing proteins are classified into a distinct functional subclass of the CRAL_TRIO/Sec14 superfamily, with ∼175 BCH domain–containing proteins (in which 14 of them are in human) present across a range of eukaryotic species (16). Some well-studied BCH domain–containing proteins include BNIP-2, BNIP-H (CAYTAXIN), BNIP-XL, BNIP-Sα, p50RhoGAP (ARHGAP1), and BPGAP1 (ARHGAP8), with evidence to show their involvement in cell elongation, retraction, membrane protrusion, and other aspects of active morphogenesis during cell migration, growth activation and suppression, myoblast differentiation, and neuritogenesis (1721). Aside from interacting with small GTPases and their regulators, some of these proteins can also associate with other signaling proteins, such as fibroblast growth factor receptor tyrosine kinases, myogenic Cdo receptor, p38-MAP kinase, Mek2/MP1, and metabolic enzymes, such as glutaminase and ATP-citrate lyase (1726). Despite the functional diversity and versatility of BCH domain–containing proteins, the structure of the BCH domain and its various modes of interaction remain unknown. The BCH domain resembles the Sec14 domain (from the CRAL-TRIO family) (16, 27, 28), a domain with lipid-binding characteristics, which may suggest that the BCH domain could have a similar binding strategy. However, to date, the binding and the role of lipids in BCH domain function remain inconclusive.Of the BCH domain–containing proteins, we have focused on the structure and function of p50RhoGAP. p50RhoGAP comprises an N-terminal BCH domain and a C-terminal GAP domain separated by a proline-rich region. We found that p50RhoGAP contains a noncanonical RhoA-binding motif in its BCH domain and is associated with GAP-mediated cell rounding (13). Further, we showed previously that deletion of the BCH domain dramatically enhanced the activity of the adjacent GAP domain (13); however, the full dynamics of this interaction is unclear. Previously, it has been reported that the BCH and other domains regulate GAP activity in an autoinhibited manner (18, 21, 29, 30) involving the interactions of both the BCH and GAP domains, albeit the mechanism remains to be investigated. It has also been shown that a lipid moiety on Rac1 (a Rho GTPase) is necessary for its inactivation by p50RhoGAP (29, 31), which may imply a role in lipid binding. An understanding of how the BCH domain coordinates with the GAP domain to affect the local activity of RhoA and other GTPases would offer a previously unknown insight into the multifaceted regulation of Rho GTPase inactivation.To understand the BCH domain–mediated regulation of p50RhoGAP and RhoA activities, we have determined the crystal structure of a homologous p50RhoGAP BCH domain from S. pombe for functional interrogation. We show that the BCH domain adopts an intertwined dimeric structure with asymmetric monomers and harbors a unique RhoA-interacting loop and a lipid-binding pocket. Our results show that the lipid-binding region of the BCH domain helps to anchor the prenylation tail of RhoA while the loop interacts directly with RhoA. Moreover, we show that a mutation in the β5-strand releases the autoinhibition of the GAP domain by the BCH domain. This renders the GAP domain active, leading to RhoA inactivation and the associated phenotypic effects in yeast and HeLa cells. The released BCH domain also contributes to enhanced p50RhoGAP–p50RhoGAP interaction. Our findings offer crucial insights into the regulation of Rho signaling by BCH domain–containing proteins.  相似文献   
129.
130.
目的 探讨心理干预对减轻耳鼻喉科手术后疼痛程度的影响.方法 选取2011年2月至2014年9月在我院行耳鼻喉部手术的120例患者作为研究对象,采用随机数字表法将所选患者分为研究组和对照组各60例,研究组给予针对性心理护理干预,对照组给予耳鼻喉科常规护理,使用视觉模拟评分法(VAS)评价疼痛程度,比较两组患者术后疼痛分级、疼痛程度、住院时间和护理满意度.结果 研究组术后总疼痛率为11.7%,显著低于对照组的61.7%(P<0.05);研究组患者术后24、72 h VAS评分均优于对照组(P<0.05),住院时间短于对照组(P<0.05);研究组护理满意度为96.7%,高于对照组的83.3% (P<0.05).结论 心理护理干预用于耳鼻喉部手术术后疼痛患者效果确切,可有效减轻术后疼痛,促进患者早日康复.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号