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   169250篇
  免费   15348篇
  国内免费   8889篇
耳鼻咽喉   1609篇
儿科学   2725篇
妇产科学   3260篇
基础医学   15693篇
口腔科学   3507篇
临床医学   20692篇
内科学   23274篇
皮肤病学   2013篇
神经病学   7382篇
特种医学   5810篇
外国民族医学   40篇
外科学   16681篇
综合类   30902篇
现状与发展   25篇
一般理论   18篇
预防医学   14348篇
眼科学   3811篇
药学   18354篇
  176篇
中国医学   10960篇
肿瘤学   12207篇
  2024年   543篇
  2023年   2244篇
  2022年   5362篇
  2021年   7183篇
  2020年   5587篇
  2019年   4457篇
  2018年   4750篇
  2017年   4821篇
  2016年   4160篇
  2015年   6788篇
  2014年   8860篇
  2013年   9550篇
  2012年   13916篇
  2011年   14854篇
  2010年   11120篇
  2009年   9406篇
  2008年   11056篇
  2007年   10834篇
  2006年   10079篇
  2005年   8925篇
  2004年   6344篇
  2003年   5574篇
  2002年   4512篇
  2001年   3912篇
  2000年   3437篇
  1999年   2876篇
  1998年   1375篇
  1997年   1259篇
  1996年   1031篇
  1995年   976篇
  1994年   910篇
  1993年   522篇
  1992年   896篇
  1991年   810篇
  1990年   679篇
  1989年   580篇
  1988年   527篇
  1987年   457篇
  1986年   364篇
  1985年   289篇
  1984年   186篇
  1983年   176篇
  1982年   98篇
  1981年   93篇
  1979年   140篇
  1978年   111篇
  1977年   83篇
  1974年   94篇
  1973年   72篇
  1972年   87篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
61.
The effect of olestra on vitamin D status was assessed in a 6-wk, double-blind, placebo-controlled study involving 202 free-living adults. Subjects consumed a total of 20 g/d of olestra or triglycerides in cookies eaten at each meal. A 20-micrograms ergocalciferol capsule was taken with each morning meal. Serum 25-hydroxyergocalciferol (25-OHD2) concentrations rose from approximately 5.7 to 39.0 and 31.7 nmol/L in the placebo and olestra groups, respectively, at week 6. At week 6, 25-OHD2 contributed 46-54% to total serum 25-OHD concentration compared with 11% at baseline. The 19% decrease in serum 25-OHD2 concentrations produced by olestra in this study is equivalent to a decrease of approximately 1.2 nmol/L under nonsupplemented dietary conditions. Ingesting 20 g olestra/d in the diet is thus not expected to affect vitamin D nutritional status.  相似文献   
62.
63.
目的:探讨成人结肠冗长症的诊断与围手术期处理经验,提高对该病的诊治水平。方法:回顾性分析42例成人结肠冗长症的临床资料,并作了随访观察。结果:32例患者(75.7%)有顽固性便秘,18例患者(42.9%)存在反复不完全肠梗阻,16例患者(38.1%)便秘与腹泻交替出现,以便秘为主。39例经X线钡剂灌肠透视确诊。急诊手术3例,择期手术39例。41例(97.6%)病理检查于镜下可见典型改变。42例均行不同长度的肠段切除,4例加行乙状结肠固定术。术后随访率为83.3%(35/42),28例症状消失,4例仍有症状,保守治疗有效果,3例再次手术,术后症状消失。结论:典型的病史和X线钡剂灌肠可确诊成人结肠冗长症,外科手术是治疗本病的最终有效措施。  相似文献   
64.
富含血管的听神经瘤   总被引:1,自引:0,他引:1  
目的探讨富含血管的听神经瘤的手术治疗。方法复习20年(1975—1995)手术治疗单侧听神经瘤90例,其中4例为富含血管的听神经瘤(HAT),与86例非富含血管的听神经瘤(NHAT),做回顾性分析,据临床表现、放射学检查、手术所见做比较。结果HAT较NHAT年轻(28±10与54±17岁)(P〈0.01),MRI显示HAT为实质性,无肿瘤囊变,多数较NHAT为大(P〈0.05);MRI示HAT有多个代表较大引流静脉的流空效应;经皮股动脉、椎动脉造影显示HAT有广泛的肿瘤着色及早期引流静脉的充盈,并证实由椎基动脉供血。过去文献报道认为以分期手术为宜。作者在控制性低血压麻醉下,成功地完成了4例HAT的切除术,未输血,术后无明显伤残。结论HAT是一种实质性大型肿瘤,出现于青年期,血管造影能够提供特征性发现。MRI能显示肿瘤表面的流空效应而确诊。采用控制性低血压麻醉有望能一期全切除肿瘤。  相似文献   
65.
Objective Sstudy effect of nuclear factor-κB ASOND on I type collagen expression and rat hepatic stellate cells(HSC)proliferation.Methods Rat HSCs were separated by affusing and digestingof Ⅳ type collagenenzyme and density acentric method.Lipid-mediated NF-κB p65 ASOND(0.001,0.01,0.1,1μmol/L)Was transferred into rat HSCs.Toxicity of HSCs caused by NF-κB p65 ASOND and activity of LDH were determined by trypan blue staining.Proliferation affection of transferring NF-κB p65 ASOND into HSCs was determined by MTT.In different concentration NF-κB p65 ASOND.expression of Ⅰ type collagen stimulated by 1mg/L TNF-αwas determined by RT-PCR and ELISA.Results After transfection of NF-κB p65 ASODN,expression of NF-κB protein in HSCs was decreasing.Toxicity experiment indicated that NF-κB p65 ASOND of different concentration(0.001,0.01,0.1 and 1.0 μmol/L)had no effect on HSCs livability and LDH activity(P<0.05).Four different concentration NF-κ B p65 ASOND could restrain HSCs proliferation stimulated by 1 mg/L TNF-α.The expression of I type collagen and mRNA stimulated by 1mg/LTNF-αwas increased,and had a positive correlation with concentration(P>0.05).Conclusion NF-κB p65 ASOND may depress NF-κB activity to restrain HSCs proliferation and Ⅰ type collagen expression,and reduce extracellular matrix.  相似文献   
66.
目的应用人精子头-尾膜完整性试验,比较生育力组与不育组男性精液4种精子膜完整性类型的差异.方法精液标本分为生育力组(n=32)和不育组(n=50),采用"低渗肿胀-伊红拒染"结合试验,检测人精子头-尾膜完整性.结果头膜尾膜均损伤的Ⅰ型精子和头膜损伤-尾膜完整的Ⅲ型精子,生育组和不育组存在明显差异(P<0.01);头膜完整-尾膜损伤的Ⅱ型精子,生育组和不育组无明显差异(P>0.05);头膜-尾膜均完整的Ⅳ型精子,生育组明显高于不育组(P<0.01);Ⅳ型精子率与生育组精子活动率(n=32, r=0.82,P<0.01)和不育组精子活动率(n=50,r=0.80,P<0.01)均呈显著相关性.结论生育组具有较多头膜-尾膜均完整的精子."低渗肿胀-伊红拒染"结合试验能够清晰显示包括过渡型膜损伤的4种膜完整性类型的精子,精子头-尾膜完整性可以作为评价精子生理学的一项检测指标.  相似文献   
67.
The present study was undertaken to examine whether the second generation antibiotic drug minocycline attenuates behavioral changes (eg, acute hyperlocomotion and prepulse inhibition (PPI) deficits) in mice after the administration of the N-methyl-D-aspartate (NMDA) receptor antagonist (+)-MK-801 (dizocilpine). Dizocilpine (0.1 mg/kg)-induced hyperlocomotion was significantly attenuated by pretreatment with minocycline (40 mg/kg). Furthermore, the PPI deficits after a single administration of dizocilpine (0.1 mg/kg) were attenuated by pretreatment with minocycline (10, 20, or 40 mg/kg), in a dose-dependent manner. Moreover, in vivo microdialysis study in the free-moving mice revealed that pretreatment with minocycline (40 mg/kg, i.p.) significantly attenuated the increase of extracellular dopamine (DA) levels in the frontal cortex and striatum after administration of dizocilpine (0.1 mg/kg), suggesting that the inhibition of dizocilpine-induced DA release by minocycline may, at least in part, be implicated in the mechanism of action of minocycline with respect to dizocilpine-induced behavioral changes in mice. These findings suggest that minocycline could attenuate behavioral changes in mice after the administration of the NMDA receptor antagonist dizocilpine. Therefore, it is possible that minocycline would be a potential therapeutic drug for schizophrenia.  相似文献   
68.
High cord blood immunoglobulin E (cbIgE) is known to be associated with increased risks of atopic diseases in childhood. The relationship between genetic polymorphisms and high cbIgE has not been well documented. A cross-sectional study was conducted to assess the association between cbIgE and genetic polymorphisms of interleukin (IL)-4 -590C/T, the beta-subunit of the high-affinity receptor for IgE (FcepsilonRI-beta) E237G, lymphotoxin (LT)-alphaNcoI alleles, and tumor necrosis factor (TNF)-alpha -308G/A. A total of 320 mother-neonate pairs were recruited from four maternity hospitals from different locations of Taiwan. Cord blood was obtained and assayed for cbIgE. Polymerase chain reaction followed by restriction fragment length polymorphism was used to assess the genotypes. Three hundred pairs of mothers and neonates were included in the final analysis. Infants with IL-4 -590 C allele were found to have higher risk of elevated cbIgE (> or =0.35 IU/ml, 24.3%) (p = 0.004). After adjusting for gender, birth order, maternal age, and history of allergic disease in maternal and paternal families, odds ratios for CC and CT genotypes were 4.41 and 3.16 (95% confidence interval 0.78-22.67, and 1.66-6.13), respectively, using TT genotype as reference. The genotypes of FcepsilonRI-beta, LT-alpha, and TNF-alpha were not associated with cbIgE before or after the adjustment. Our finding suggested a significant association of cbIgE with genetic polymorphism of IL-4 -590C/T, but not with the genotypes of FcepsilonRI-beta, LT-alpha, and TNF-alpha.  相似文献   
69.
70.
目的 探讨应用显微外科技术延迟一期修复四肢外周神经损伤的治疗体会。方法 应用显微外科技术延迟一期修复各种原因所致的四肢外周神经损伤38例41条,手术方法包括神经瘢痕松解、神经直接缝合术等。结果 术后随访6个月~7年,平均33个月,优良率为81.6%。结论 对失去一期修复手术治疗机会的周围神经损伤患者应尽早行延迟一期手术,可取得较好疗效。  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