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   18765篇
  免费   859篇
  国内免费   267篇
耳鼻咽喉   297篇
儿科学   324篇
妇产科学   393篇
基础医学   1301篇
口腔科学   4627篇
临床医学   1455篇
内科学   1281篇
皮肤病学   551篇
神经病学   223篇
特种医学   228篇
外科学   741篇
综合类   1876篇
现状与发展   1篇
预防医学   1542篇
眼科学   51篇
药学   2350篇
  7篇
中国医学   913篇
肿瘤学   1730篇
  2024年   95篇
  2023年   369篇
  2022年   581篇
  2021年   717篇
  2020年   638篇
  2019年   873篇
  2018年   924篇
  2017年   613篇
  2016年   627篇
  2015年   567篇
  2014年   1213篇
  2013年   1258篇
  2012年   1048篇
  2011年   1282篇
  2010年   852篇
  2009年   873篇
  2008年   846篇
  2007年   823篇
  2006年   690篇
  2005年   640篇
  2004年   541篇
  2003年   447篇
  2002年   336篇
  2001年   339篇
  2000年   255篇
  1999年   241篇
  1998年   218篇
  1997年   197篇
  1996年   158篇
  1995年   159篇
  1994年   139篇
  1993年   89篇
  1992年   109篇
  1991年   82篇
  1990年   91篇
  1989年   97篇
  1988年   75篇
  1987年   61篇
  1986年   45篇
  1985年   133篇
  1984年   98篇
  1983年   69篇
  1982年   72篇
  1981年   57篇
  1980年   38篇
  1979年   34篇
  1978年   33篇
  1977年   25篇
  1976年   38篇
  1975年   21篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
目的:优选养血口服液提取工艺。方法:以干膏收率和总黄酮的含量为指标,采用正交试验法对养血口服液提取工艺进行研究。结果:确定最佳工艺条件为:水煎煮2次,第一次加10倍量水,煎煮1.5小时;第二次加8倍量水煎1,所得煎煮液浓缩至1ml,含1g生药,醇沉浓度为70%。结论:本法可用于养血口服液的生产。  相似文献   
72.
Candida krusei发酵生产甘油过程中,菌体生长由玉米浆限制,菌体对玉米浆的得率为1.63g/g,培养其中玉米浆浓度相同时,增加渗透压或通过流加补料限制生长阶段的菌体生长,可使甘油生产阶段的比耗糖速率减慢,比耗糖速率保持在不很高的水平,可以因消耗的葡萄糖用于生长,维持,甘油和副产物形成所占比例的变化而提高甘油得率。  相似文献   
73.
The tumor immune microenvironment of oral tongue squamous cell carcinoma may be accountable for differences in clinical behavior, particularly between different age groups. We performed RNA expression profiling and evaluated tumor infiltrating lymphocytes (TILs) and their T-cell subsets in order to assess the functional status of oral tongue squamous cell carcinoma tumor microenvironment and detect potentially clinically useful associations. Archival surgical pathology material from sixteen oral tongue squamous cell carcinoma patients was microscopically evaluated for TIL densities. RNA was extracted from macrodissected whole tumor sections and normal controls and RNA expression profiling was performed by the NanoString PanCancer IO 360 Gene Expression Panel. Immunostains for CD4, CD8 and FOXP3 were evaluated manually and by digital image analysis. Oral tongue squamous cell carcinomas had increased TIL densities, numerically dominated by CD4 + T cells, followed by CD8 + and FOXP3 + T cells. RNA expression profiling of tumors versus normal controls showed tumor signature upregulation in inhibitory immune signaling (CTLA4, TIGIT and PD-L2), followed by inhibitory tumor mechanisms (IDO1, TGF-β, B7-H3 and PD-L1). Patients older than 44 years showed a tumor microenvironment with increased Tregs and CTLA4 expression. Immunohistochemically assessed CD8% correlated well with molecular signatures related to CD8 + cytotoxic T-cell functions. FOXP3% correlated significantly with CTLA4 upregulation. CTLA4 molecular signature could be predicted by FOXP3% assessed by immunohistochemistry (R2 = 0.619, p = 0.026). Oral tongue squamous cell carcinoma hosts a complex inhibitory immune microenvironment, partially reflected in immunohistochemically quantified CD8 + and FOXP3 + T-cell subsets. Immunohistochemistry can be a useful screening tool for detecting tumors with upregulated expression of the targetable molecule CTLA4.Electronic supplementary materialThe online version of this article (10.1007/s12105-020-01229-w) contains supplementary material, which is available to authorized users.  相似文献   
74.
75.
To explore the feasibility of detection of the level of NF-κB-dependent cytokines in oral fluids from patient with oral lichen planus (OLP) for clinical application, 13 OLP subjects were enrolled in the study as were 13 age–sex-matched controls. In each subject, the whole unstimulated saliva (WUS), mixture of saliva and isotonic saline oral rinse (Saliva-NaCl), and lesion tissue transudates (TT) were collected by standard techniques. The level of cytokines, TNF-alpha, IL-1-alpha, IL-6, and IL-8 in three types of oral fluids was determined by ELISA. In the three types of oral fluids, a significantly higher level of these cytokines was detected in OLP patients than in normal controls. These results indicate that NF-κB-dependent inflammatory cytokines may be detected at increased levels in certain oral fluids which may have diagnostic and prognostic potential for monitoring disease activity and making therapeutic decisions in patients with OLP.  相似文献   
76.
M. Pedersen    H. Permin    C. Jensen    P. Stahl  Skov  S. Norn  V. Faber 《Allergy》1987,42(4):291-297
Type I allergy against some common microorganisms was investigated in 14 patients with AIDS and 11 human immunodeficiency virus (HIV) antibody-positive homosexual men, and in a control group consisting of 13 heterosexual men without HIV antibodies. Basophil histamine release technique was used as a sensitive method to detect type I allergy against Candida albicans (CA), Herpes simplex virus type I (HSV-I) and cytomegalovirus (CMV). Of the 14 AIDS patients 11 (78%) showed significant histamine release when stimulated with CA, and HSV-I caused release in 10 (71%), whereas no response was obtained by CMV. In the group of HIV antibody-positive men only one released histamine when stimulated with CA and HSV-I and this patient also had lymphadenopathia. In contrast to these results, no release of histamine was obtained in the control group consisting of 13 heterosexual men. The histamine release caused by CA and HSV-I is mediated by an immunological reaction, since the release was abolished and regained by removal from and refixation to the cell surface of the cell-bound immunoglobulins. These results suggest an involvement of type I allergy as a pathogenetic co-factor in some infections in AIDS, and allergic type I reactions to CA and HSV-I might be an indicator for the presence of manifest AIDS.  相似文献   
77.
Copper ions were found to inhibit the rate of growth in broth culture of Streptococcus mitis, Streptococcus mutans, Streptococcus salivarious, Streptococcus sanguis, Actinomyces viscosus and Actinomyces naeslundii. In all cases, 10?3 M copper inhibited the rate of growth, whereas 10?4 M and lower concentrations had little or no effect. At the concentrations used in mouthwashes one mode of action of copper ions is to reduce the rate of growth of oral bacteria in vitro.  相似文献   
78.
Sexually transmitted diseases pose a health threat to families, society and the nation but there is no report of these diseases to help health planners in Bauchi. Medical records were examined from 1983 to 1988 in two major health institutions, the University Medical Centre and the Specialist Hospital to determine the extent and types of these diseases in Bauchi.

Urethritis, syphilis, candidiasis, pelvic inflammatory diseases, trichomoniasis were very common. Gonorrhoea was the least reported disease.

The cases of syphilis reported at the Specialist Hospital nearly doubled from 111 in 1983 to 214 in 1988, urethritis increased from 141 to 232. In the University Medical Centre, all reported cases of sexually transmitted diseases decreased from 1983 to 1988.

Data analysis of cases common to the Specialist Hospital and the University Medical Centre gave no significant difference between the institutions at the 95% level of confidence.  相似文献   

79.
Epidemiological study of pathogenic fungi in China: 1986 and 1996   总被引:2,自引:2,他引:0  
目的 研究 1986年 - 1996年 ,我国致病真菌菌群的变化情况。方法  1986年 1月 1日 - 12月 31日和 1996年 1月 1日 - 12月 31日在全国 2 5个省、市、自治区 4 0多个有代表性的单位对临床或现场确定的致病菌进行了动态研究 ,就病原菌变迁、各区动态情况和具体疾病等作了详细分析。结果 发现 10年间较易治疗的皮肤癣菌比例下降 ,而较难治疗的酵母菌和霉菌比例升高。结论  10年间致病真菌菌群的变化较大 ,我们应根据变化情况进行相应的研究及制定出相应治疗措施  相似文献   
80.
目的:探讨沙利霉素(salinomycin)对口腔鳞癌细胞增殖和凋亡的影响,并初步探讨沙利霉素对信号通路的影响。方法:培养口腔鳞状细胞癌细胞系CAL-27,将1、2、4、8、16、32 μmol/L沙利霉素和1.25、2.5、5、10、20、40、80 μmol/L顺铂与CAL-27细胞共同培养,24 h和48 h后用细胞计数试剂盒-8(cell counting kit-8,CCK-8)法检测沙利霉素和顺铂对CAL-27细胞增殖的影响;0、2、4、8 μmol/L沙利霉素和0、5、10、20 μmol/L顺铂与CAL-27细胞共培养48 h后,通过流式细胞术检测沙利霉素和顺铂对CAL-27细胞周期的影响,蛋白免疫印迹法(Western blot)检测CAL-27细胞中天冬氨酸特异性半胱氨酸蛋白酶-3(cysteine-containing aspartate-specific proteases-3,Caspase-3)、天冬氨酸特异性半胱氨酸蛋白酶-9(cysteine-containing aspartate-specific proteases-9,Caspase-9)、脱氧核糖核酸(deoxyribonucleic acid,DNA)修复酶(poly ADP-ribose polymerase,PARP)、蛋白激酶B(protein kinase B, Akt)和磷酸化蛋白激酶B (phosphorylated protein kinase B,p-Akt)的表达。结果:CCK-8实验表明沙利霉素和顺铂均能显著抑制口腔鳞状细胞癌CAL-27细胞增殖,且抑制作用呈时间依赖性和药物浓度依赖性,但是相对于临床一线化疗药物顺铂而言,沙利霉素对CAL-27细胞增殖的抑制效果更加显著(P<0.001)。细胞周期检测表明,与加入二甲基亚砜(dimethyl sulfoxide,DMSO)的对照组相比,8 μmol/L沙利霉素与CAL-27细胞共同培养48 h后,细胞休眠期/DNA合成前期的CAL-27细胞比例明显升高(40.40%±1.99% vs.64.46%±0.90%,P<0.05), DNA合成期和DNA合成后期/有丝分裂期的CAL-27细胞比例出现降低(24.32%±2.30% vs.18.73%±0.61%,P<0.05,35.01%±1.24% vs.16.54%±1.31%,P<0.05);顺铂对CAL-27细胞周期没有特异性改变。蛋白免疫印迹法结果显示,沙利霉素在上调CAL-27细胞中Caspase-3和 Caspase-9蛋白表达(P<0.05)的同时下调PARP、Akt和p-Akt蛋白的表达(P<0.05)。结论:相对于顺铂而言,沙利霉素对CAL-27细胞增殖有更强的抑制作用,并且能将口腔鳞状细胞癌CAL-27细胞周期阻滞在细胞休眠期/DNA合成前期,同时能够诱导CAL-27细胞发生凋亡,这一机制可能和Akt/p-Akt 信号通路相关。  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