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   272012篇
  免费   15684篇
  国内免费   7636篇
耳鼻咽喉   3485篇
儿科学   8697篇
妇产科学   3136篇
基础医学   18794篇
口腔科学   6596篇
临床医学   32589篇
内科学   45715篇
皮肤病学   3247篇
神经病学   13615篇
特种医学   27256篇
外国民族医学   43篇
外科学   37493篇
综合类   26330篇
现状与发展   29篇
预防医学   16319篇
眼科学   7433篇
药学   25686篇
  91篇
中国医学   4790篇
肿瘤学   13988篇
  2023年   2750篇
  2022年   5947篇
  2021年   12440篇
  2020年   6927篇
  2019年   12633篇
  2018年   7350篇
  2017年   6468篇
  2016年   8377篇
  2015年   11361篇
  2014年   20764篇
  2013年   17877篇
  2012年   21433篇
  2011年   18815篇
  2010年   17013篇
  2009年   16591篇
  2008年   15402篇
  2007年   15411篇
  2006年   13296篇
  2005年   9324篇
  2004年   5555篇
  2003年   4729篇
  2002年   3830篇
  2001年   3192篇
  2000年   2757篇
  1999年   1927篇
  1998年   2233篇
  1997年   2100篇
  1996年   1738篇
  1995年   1722篇
  1994年   1640篇
  1993年   1259篇
  1992年   1390篇
  1991年   1230篇
  1990年   1241篇
  1989年   1201篇
  1988年   1118篇
  1987年   999篇
  1986年   794篇
  1985年   1733篇
  1984年   1904篇
  1983年   1351篇
  1982年   1477篇
  1981年   1429篇
  1980年   1227篇
  1979年   1045篇
  1978年   795篇
  1977年   801篇
  1976年   682篇
  1974年   458篇
  1973年   433篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
81.
82.
目的比较3%高渗盐水和20%甘露醇治疗重症动脉瘤性蛛网膜下腔出血所致颅内压增高的疗效.方法25例动脉瘤性蛛网膜下腔出血患者出现颅内压增高事件时, 随机交替接受等渗透剂量的160 mL 3%高渗盐水与150 mL 20%甘露醇进行降低颅内压治疗, 连续监测患者颅内压、平均动脉压、脑灌注压及中心静脉压.记录有效降低颅内压持续时间、颅内压最大降幅及其时间, 用药前及用药后1 h、3 h血钠水平及血浆渗透压.结果3%高渗盐水和20%甘露醇均可降低颅内压(均 P < 0.01), 两者的降低颅内压作用持续时间及颅内压降幅差异均无统计学意义(均 P >0.05).患者脑灌注压较用药前均上升(均 P < 0.01), 平均动脉压先上升后下降, 但差异无统计学意义( P >0.05).患者中心静脉压稍有波动, 但差异均无统计学意义(均 P >0.05).20%甘露醇治疗后患者血钠下降, 3%高渗盐水治疗后患者血钠值上升, 变化均有统计学意义(均 P < 0.05).20%甘露醇及3%高渗盐水治疗后患者血浆渗透压均先上升后下降, 变化均有统计学意义(均 P < 0.01). 结论3%高渗盐水可作为治疗动脉瘤性蛛网膜下腔出血所致颅内压增高患者的一线治疗药物.  相似文献   
83.
The acquisition of chemoresistance remains a major cause of cancer mortality due to the limited accessibility of targeted or immune therapies. However, given that severe alterations of molecular features during epithelial‐to‐mesenchymal transition (EMT) lead to acquired chemoresistance, emerging studies have focused on identifying targetable drivers associated with acquired chemoresistance. Particularly, AXL, a key receptor tyrosine kinase that confers resistance against targets and chemotherapeutics, is highly expressed in mesenchymal cancer cells. However, the underlying mechanism of AXL induction in mesenchymal cancer cells is poorly understood. Our study revealed that the YAP signature, which was highly enriched in mesenchymal‐type lung cancer, was closely correlated to AXL expression in 181 lung cancer cell lines. Moreover, using isogenic lung cancer cell pairs, we also found that doxorubicin treatment induced YAP nuclear translocation in mesenchymal‐type lung cancer cells to induce AXL expression. Additionally, the concurrent activation of TGFβ signaling coordinated YAP‐dependent AXL expression through SMAD4. These data suggest that crosstalk between YAP and the TGFβ/SMAD axis upon treatment with chemotherapeutics might be a promising target to improve chemosensitivity in mesenchymal‐type lung cancer.

Abbreviations

AUC
area under the curve
AXL
AXL receptor tyrosine kinase
BCL2
B‐cell lymphoma 2
CTD2
cancer target discovery and development
CTGF
connective tissue growth factor
DEG
differentially expressed genes
DOXO
doxorubicin
EMT
epithelial–mesenchymal transition
Eto
etoposide
FDA
Food and Drug Administration
ITGB3
integrin beta‐3
MAPK
mitogen‐activated protein kinase
MMP2
matrix metalloproteinase‐2
MMP9
matrix metalloproteinase‐9
mRNA
messenger RNA
NF‐κB
nuclear factor kappa‐light‐chain‐enhancer of activated B cells
SBE
SMAD binding element
SERPINE1
serpin family E member 1
siRNA
small interfering RNA
ssGSEA
single‐sample gene set enrichment analysis
TCGA
The Cancer Genome Atlas
TGFβ
transforming growth factor beta
YAP
Yes‐associated protein
YAP8SA
mutants of inhibitory phosphorylation site at eight serine to Alanine of YAP
ZEB1
zinc finger E‐box binding homeobox 1
ZEB2
zinc finger E‐box‐binding homeobox 2
  相似文献   
84.
85.
背景 呼吸道合胞病毒(RSV)毛细支气管炎易出现反复喘息,且下呼吸道分泌物中半胱氨酸白三烯(CysLTs)水平升高。而孟鲁司特是一种白三烯受体拮抗剂,关于其治疗RSV毛细支气管炎症状的研究相对较少。目的 探讨孟鲁司特改善婴幼儿RSV毛细支气管炎后症状及减轻反复喘息发作的有效性和安全性。方法 2015年6月-2017年6月连续纳入在潍坊市妇幼保健院出院的RSV毛细支气管炎患儿,随机分为治疗组、对照组。Ⅰ期,治疗组:口服孟鲁司特颗粒(4 mg)12周,1次/d;对照组:口服安慰剂12周,1次/d。对两组无症状天数、个人日记评分进行评估。随访9个月(Ⅱ期),观察Ⅰ+Ⅱ期反复喘息人数和医疗资源应用情况等。依据意向性分析(ITT)原则,应用全分析集(FAS)分析数据。结果 共纳入研究对象186例,治疗组92例,对照组94例。治疗组完成Ⅰ期研究的患儿为89例,对照组为90例;治疗组完成Ⅰ+Ⅱ期的患儿为84例,对照组为86例。治疗组平均依从性为97.8%(7 560/7 728),对照组平均依从性为97.4%(7 690/7 896),两组患儿平均依从性比较,差异无统计学意义(χ2=3.16,P=0.07)。在Ⅰ期研究期间,两组无症状天数、日间无症状天数、夜间无症状天数、个人日记评分比较,差异均无统计学意义(P>0.05)。在整个研究过程中(Ⅰ+Ⅱ期),治疗组RSV毛细支气管炎喘息复发人数少于对照组(P<0.05),治疗组喘息患儿出现2次及以上喘息比例低于对照组(χ2=5.14,P=0.02)。Ⅰ+Ⅱ期研究期间治疗组医疗资源应用人数、β-受体激动剂应用人数、糖皮质激素应用人数、住院人数低于对照组(P<0.05)。在事后亚组分析中,治疗组有湿疹史与父母哮喘史的患儿中无症状天数〔(49.7±20.2)、(51.3±20.9)d〕多于对照组〔(36.3±20.4)、(37.8±19.3)d〕(t=2.19,P=0.03;t=2.24,P=0.03)。整个研究过程中没有患儿因不良反应退出研究,两组间胃肠道紊乱、皮疹、转氨酶升高发生率比较,差异均无统计学意义(χ2=0.23,P=0.63;χ2=0.03,P=0.86;χ2=0.15,P=0.69)。结论 口服孟鲁司特(4 mg)12周不能改善RSV毛细支气管炎患儿呼吸道症状,但能降低患儿反复喘息发作次数。口服孟鲁司特(4 mg)有一定效果且安全。  相似文献   
86.
《The ocular surface》2020,18(4):926-935
PurposeTo visualize and quantify vascular networks in individuals with ocular surface squamous neoplasia (OSSN) through optical coherence tomography angiography (OCTA).MethodCross-sectional study of OSSN patients. Vascular networks were measured by OCTA in the epithelium and sub-epithelial space in the tumors, adjacent tissue, and in the contralateral eye. Vessel area density (VAD, percent of blood vessels within 2.14 mm2), was calculated for each location. Total tumor density (TTD, percent of blood vessels within the entire tumor) was calculated. VAD was assessed separately for corneal and conjunctival locations and compared.ResultsFifteen patients with OSSN were included. The mean age was 61 ± 12 years and the majority were male (80%). The mean tumor area, volume, depth, and TTD were 28.0 ± 9.0 mm2 (range, 10.9–39.7), 9.1 ± 4.1 mm3 (range, 3.4–18.8), 334 ± 125 μm (range, 177–571), and 33.2% ± 11.0% (range, 18.7–58.8), respectively. The VAD was highest within the tumor (28.9% ± 8.7%) followed by the adjacent sub-epithelial tissue and the tissue underneath the conjunctival component of tumor. These densities were higher than the VAD in the tissues of the non-involved eye (all P < 0.05). The VAD within conjunctival component of tumor was significantly higher than those with corneal component (29.8% ± 9.5% vs. 21.1% ± 5.5%, p = 0.006). The VAD under conjunctival tumor was also significantly higher than under corneal component (24.1% ± 7.8% vs. 17.0% ± 6.1%, p = 0.024).ConclusionsOCTA imaging allowed for visualization and quantification of vessel structure and density within, under, and surrounding OSSN.  相似文献   
87.
目的 了解某设备实验条件下不同位置脉冲X射线电离辐射水平,提出适当的防护建议。方法 采用热释光测量方法,分别在设备舱周围不同方向不同距离布放热释光剂量计,累积一定数量脉冲辐射后进行测量;采用电离室型X、γ剂量率仪(FJ-347A)实时测量工作状态下不同距离处电离辐射剂量率水平。依据《电离辐射防护与辐射源安全基本标准》(GB18871—2002)规定的职业照射人员和公众个人剂量限值提出不同工作位辐射防护建议。结果 热释光剂量计累计接收3 000个脉冲辐射,设备舱外壁0.01~8.98 mGy,顶部0.01~15.67 mGy,距外壁1~12 m之间0.01~2.18 mGy,工作位0 mGy。工作状态下,X射线剂量率仪测得距设备舱外侧壁1~20 m之间空气比释动能率范围0.26~16 mGy/h。结论 热释光剂量计、电离室型剂量率仪测量结果基本一致,说明两种方法均可用于脉冲X射线测量;工作状态下设备舱外近距离处辐射剂量率较高,可通过采取防护措施或者限制人员工作量以满足辐射防护要求。  相似文献   
88.
《Injury》2022,53(2):676-682
Aim3D-printed implants could improve the capture of fracture fragments for improved stability of tibial plateau fracture fixation. The aim of this study was to compare the biomechanical strength of fixation constructs using standard and customised 3D-printed proximal tibial locking plates for fixation of tibial plateau fractures.MethodsThis is a biomechanical study utilising six pairs of cadaveric tibiae. Fractures were created in an identical fashion using an osteotome and mallet, and fixed using either a standard, commercially-available proximal tibia locking plate or a customised 3D-printed plate. Design and production of the customised plates followed a “3D printing at point-of-care” model. Customised stainless steel 316 L plates were produced within a local additive manufacturing laboratory based upon pre-operative CT scans. Determination of implant choice within each cadaver pair was performed via simple randomisation. Following fracture fixation, the tibiae were skeletalised and biomechanically tested using a customised loading jig and a size-matched femoral knee prosthesis. The constructs were loaded cyclically from 100 N to approximately three times the cadaveric body-weight at 5 Hz for 10 000 cycles. Every 1000 cycles, the test was paused and the tibia was physically checked for failure. If failure had not occurred by the end of the testing cycle, the construct was loaded to failure and the load at which the construct failed was noted.ResultsFixation constructs using the 3D-printed plates performed comparably to those using the standard plates. There was no significant difference in the degree of fracture fragment displacement in both constructs. Overall longitudinal construct stiffness and load to failure was higher in the 3D-plates group but this did not reach statistical significance.ConclusionProduction of customised plates for proximal tibia fractures at point-of-care is feasible, however fixation constructs with these plates did not provide any biomechanical advantage over standard plates in terms of axial loading stiffness.  相似文献   
89.
90.
Esophageal adenocarcinoma is the fastest rising cancer in the United States. It develops from long‐standing gastroesophageal reflux disease which affects >20% of the general population. It carries a very poor prognosis with 5‐year survival <20%. The disease is known to sequentially progress from reflux esophagitis to a metaplastic precursor, Barrett''s esophagus and then onto dysplasia and esophageal adenocarcinoma. However, only few patients with reflux develop Barrett''s esophagus and only a minority of these turn malignant. The reason for this heterogeneity in clinical progression is unknown. To improve patient management, molecular changes which facilitate disease progression must be identified. Animal models can provide a comprehensive functional and anatomic platform for such a study. Rats and mice have been the most widely studied but disease homology with humans has been questioned. No animal model naturally simulates the inflammation to adenocarcinoma progression as in humans, with all models requiring surgical bypass or destruction of existing antireflux mechanisms. Valuable properties of individual models could be utilized to holistically evaluate disease progression. In this review paper, we critically examined the current animal models of Barrett''s esophagus, their differences and homologies with human disease and how they have shaped our current understanding of Barrett''s carcinogenesis.  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