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   9346篇
  免费   701篇
  国内免费   447篇
耳鼻咽喉   165篇
儿科学   162篇
妇产科学   121篇
基础医学   1000篇
口腔科学   102篇
临床医学   1297篇
内科学   1219篇
皮肤病学   46篇
神经病学   622篇
特种医学   325篇
外国民族医学   9篇
外科学   910篇
综合类   1379篇
现状与发展   2篇
预防医学   661篇
眼科学   216篇
药学   1053篇
  4篇
中国医学   369篇
肿瘤学   832篇
  2024年   20篇
  2023年   100篇
  2022年   282篇
  2021年   389篇
  2020年   315篇
  2019年   261篇
  2018年   256篇
  2017年   261篇
  2016年   265篇
  2015年   334篇
  2014年   511篇
  2013年   454篇
  2012年   630篇
  2011年   692篇
  2010年   460篇
  2009年   316篇
  2008年   460篇
  2007年   499篇
  2006年   467篇
  2005年   474篇
  2004年   359篇
  2003年   314篇
  2002年   333篇
  2001年   190篇
  2000年   227篇
  1999年   285篇
  1998年   155篇
  1997年   156篇
  1996年   127篇
  1995年   115篇
  1994年   105篇
  1993年   88篇
  1992年   95篇
  1991年   71篇
  1990年   62篇
  1989年   64篇
  1988年   40篇
  1987年   33篇
  1986年   32篇
  1985年   22篇
  1984年   22篇
  1983年   18篇
  1982年   12篇
  1981年   9篇
  1980年   13篇
  1979年   16篇
  1978年   10篇
  1977年   9篇
  1973年   6篇
  1965年   8篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
82.
83.

The relationship between the migration process and speciation distribution of Cr is important for the risk assessment in the underground environment. In this work, soil columns were collected from the chromate production site, with a 40-year operation, in the groundwater depression cone area of North China plain. The relationship between chromium pollution features and the geochemical properties of soil was established, and the migration risk of Cr(VI) was assessed based on the Nemerow composite index and Hydrus-1D model. The maximum total Cr concentration in the chromium slag dumping site reached 907 mg/kg, and that in the chromate production workshop was more than 200 mg/kg across the depth. The migration of Cr might be accelerated in the soil with abundant Mn (236–1461 mg/kg) but scarce organic matters (<?0.45%). The Hydrus simulation indicated that Cr(VI) would reach a cumulative flux of 300–729 mg/cm2 after 50 years.

  相似文献   
84.
Peanut allergy is one of the most severe food allergies due to its persistency and life-threatening character. Serum IgE from patients with documented peanut hypersensitivity reactions and synthetic peptides were used to screen the linear IgE-binding epitopes on the major peanut allergen, Ara h 1. Five major epitopes that bound peanut-specific serum IgE from more than 60% of patients tested were identified. Mutational analysis of the immunodominant epitope showed that single amino acid changes had dramatic effects on IgE-binding characteristics. Mapping and characterisation of the IgE-binding epitopes on Ara h1 could be used in future immunotherapeutic approaches for peanut allergy disease.  相似文献   
85.
Overexpression of decoy receptor (DcR) 3 protein, a recently discovered member of the tumor necrosis factor receptor superfamily, was examined in 40 esophagogastrectomy specimens containing areas of Barrett esophagus (n = 27), low-grade dysplasia (n = 27), high-grade dysplasia or carcinoma in situ (n = 22), and esophageal adenocarcinoma (EAC; n = 28) with immunohistochemical analysis. The results revealed significantly more overexpression of DcR3 in high-grade dysplasia or carcinoma in situ and EAC than in benign esophageal mucosa (both P < .0001), Barrett esophagus (both P < .001), and low-grade dysplasia (P < .01 and P = .033, respectively). Low-grade dysplasia also showed significant overexpression of DcR3 compared with benign esophagus (P < .05) but not with Barrett esophagus (P > .05). DcR3 overexpression seems to negatively correlate with the grade of EAC. Our results suggest that overexpression of DcR3 protein might aid in the diagnosis of high-grade dysplasia or carcinoma in situ and EAC and also might serve as a potential therapeutic target.  相似文献   
86.
The immunohistological expression of placental alkaline phosphatase (PLAP) and PLAP-like enzyme was studied in frozen sections from a wide variety (n = 254) of normal and malignant tissues using monoclonal antibodies reactive with PLAP (H317) and PLAP/PLAP-like enzyme (H17E2; H315). PLAP/PLAP-like reactivity was seen in normal thymus, and foetal and neonatal testis, and in 21 out of 22 malignant germ cell tumours (GCTs), but was also found in normal endocervix, normal Fallopian tube and in 28 out of 167 non-GCTs (particularly in ovarian and proximal gastrointestinal tract tumours). Positivity for true PLAP (as demonstrated with H317) was seen in term placenta, in endocervix, and in Fallopian tube (but not in other normal tissues) and was commonly found in ovarian and proximal gastrointestinal tract tumours. Reactivity with H317 was unusual in malignant GCTs (2 out of 22 cases). These findings confirm that PLAP/PLAP-like positivity is a highly sensitive immunohistological marker for malignant GCTs, but one which by itself is of only moderate specificity. Furthermore, expression of true PLAP is rare in GCTs and favours instead an origin from the ovary or proximal gastrointestinal tract. The results also indicate that the predominant heat-stable alkaline phosphatase species in normal foetal and neonatal testis, and in thymus has a similar immunohistological profile to that found in malignant GCTs, and is a PLAP-like enzyme ("germ cell alkaline phosphatase") distinct from true PLAP. The occurrence of this marker in GCTs would appear to reflect increased eutopic production of an enzyme present in trace amount in corresponding normal tissues rather than a genuine example of ectopic expression.  相似文献   
87.
Direct protective effect of interleukin-10 on articular chondrocytes in vitro   总被引:14,自引:0,他引:14  
Objective To assess whether interleukin-10 (IL-10) is chondroprotective in vitro.Methods Chondrocytes were isolated from femoral cartilage of rats (7-10 days) by digesti on with collagenase Ⅱ.The first passage cells were grown in 24- well plates with DMEM, supplemented with 10% fetal bovine serum, for 2-4 days.The ce lls were then cultured in 0.1% fetal bovine serum DMEM medium, and given respec tively interleu kin-1 (IL-1) 100 μ/ml, IL-1 100 μ/ml+recombinant murine interleukin-10 ( rmIL-10) 20 ng/ml, rmIL-10 20 ng/ml, and cultured for 48 hours.Scanning el ectron morphology and immunohistochemical study of nitric oxide synthase 2 and matric metalloproteinase 3 mRNA in situ hybridization were performe d.Cell proliferation and morphology were observed under inverted microscope fr om the beginning of cell culture for three weeks.Results IL-1 stimulated granule production in the cytoplasma of chondrocytes, and the c ells died in the second and third weeks of culture.IL-10 antagonized IL-1, p rotected the cells from death and maintained chondrocyte proliferation.Scannin g electron morphology showed that IL-1 stimulated the formation of numerous mic rovilli on the cell surface, while thin and less numerous microvilli were found in cultures with IL-10.Immunohistochemical study and in situ hybridization sh owed that IL-10 inhibited NOS2 and MMP3 expression.Conclusion IL-10 not only inhibits the synthesis of inflammatory cytokines, but also direc tly protects chondrocytes by antagonizing IL-1.  相似文献   
88.
醒脑静注射液对脑出血病人高热昏迷的疗效观察   总被引:2,自引:0,他引:2  
目的:观察醒脑静注射液对脑出血病人高热与意识障碍的疗效。方法:按随机分组法将100例有高热与意识障碍的脑出血病人随机分为治疗组及对照组,治疗组在常规方法上加用醒脑静注射液,对照组采用常规方法。结果:治疗组恢复时间明显短于对照组。结论:醒脑静注射液对脑出血高热及意识障碍有明显治疗效果。  相似文献   
89.
目的:探索蝎毒抗癌多肽组分Ⅲ(antineoplastic polypeptide-Ⅲfrom APBMV,AP-Ⅲ)的分离和纯化方法。方法:蝎毒经预处理后,分别采用pharose FF阳离子交换凝胶柱(cm×5 cm交换柱,流速0.8 ml/min,梯度洗脱1 200 min)层析法和Sepharose FF阳离子交换凝胶柱与Sephadex G-50凝胶柱(柱:100cm×5 cm;流速:0.5 ml/min)联合层析法,分离AP-Ⅲ,用HPLC仪检测2种方法分离出的AP-Ⅲ的纯度及产率。结果:单独用Sepharose FF阳离子交换凝胶柱分离,AP-Ⅲ产率为2.24%,纯度为89%。Sephadex G-50凝胶柱与Sepharose FF阳离子交换凝胶柱联用,其产率及纯度分别提高至4.72%和%。结论:Sephadex G-50与Sepharose FF联用可提高AP-Ⅲ的产率及纯度,从而为开发和利用AP-Ⅲ提供了实验依据。  相似文献   
90.
为建立一种检测活细胞数的方法,作者采用三磷酸腺苷(ATP)生物荧光液闪测定法检测小鼠纤维瘤细胞株L929.ATP标准曲线工作范围为10 -9~10-5mol/ml,相关系数r=0.9963(P<0.001);当活细胞数在3×1 02~106个/ml时与发光计数值有良好的线性关系,r=0.9922(P<0.001),变异系数 CV = 1%~3%.用ATP生物荧光液闪测定法检测活细胞数灵敏、简便、准确、重复性好,用液闪计数仪即可完成测定,有较大的实用价值.  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