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   582篇
  免费   143篇
  国内免费   16篇
  741篇
  2024年   5篇
  2023年   16篇
  2022年   24篇
  2021年   35篇
  2020年   37篇
  2019年   31篇
  2018年   29篇
  2017年   35篇
  2016年   38篇
  2015年   37篇
  2014年   59篇
  2013年   53篇
  2012年   45篇
  2011年   46篇
  2010年   39篇
  2009年   19篇
  2008年   21篇
  2007年   25篇
  2006年   20篇
  2005年   23篇
  2004年   9篇
  2003年   17篇
  2002年   7篇
  2001年   2篇
  2000年   3篇
  1999年   8篇
  1998年   4篇
  1997年   8篇
  1996年   6篇
  1995年   2篇
  1994年   6篇
  1993年   2篇
  1992年   2篇
  1991年   2篇
  1990年   2篇
  1989年   2篇
  1988年   2篇
  1987年   2篇
  1986年   2篇
  1984年   2篇
  1982年   2篇
  1981年   1篇
  1980年   1篇
  1979年   3篇
  1977年   1篇
  1976年   1篇
  1975年   2篇
  1974年   1篇
  1973年   1篇
  1972年   1篇
排序方式: 共有741条查询结果,搜索用时 15 毫秒
691.
目的:探讨白细胞介素-27(Interleukin 27,IL-27)对成人全身炎症反应综合征(systemic inflammatory response syndrome, SIRS)和脓毒症的诊断价值。方法:214 例SIRS患者按入院诊断结果及感染源不同分为非脓毒症组(n=80)、肺源性脓毒症组(n= 73)和非肺源性脓毒症组(n= 61)。采用酶联免疫吸附试验(ELISA)检测各组患者血清IL-27 和降钙素原(PCT)水平;绘制受试者 工作特征曲线(ROC),判断各指标的诊断价值,分析各生物标志物的性能,判断潜在的预测变量。结果:肺源性脓毒症患者体温符 合SIRS 标准的比例为65.8%,明显高于非脓毒症患者(45.0%)及非肺源性脓毒症患者(45.9%)(P < 0.05);非肺源性脓毒症患者白 细胞数符合SIRS标准的比例为68.9%,明显高于非脓毒症患者42.5%,(P < 0.05)。确诊脓毒症后的患者血清IL-27 的AUC 为 0.655,PCT的AUC 为0.649。根据不同感染源进一步分析,肺源性和非肺源性脓毒症患者血清IL-27 水平明显高于非脓毒症患 者,肺源性和非肺源性脓毒症患者PCT 水平明显高于非脓毒症患者(P<0.01)。ROC曲线分析发现,肺源性和非肺源性脓毒症患 者血清IL-27 的AUC分别为0.657 和0.652,肺源性和非肺源性脓毒症患者PCT 的AUC 为0.667 和0.629。分别联合检测三组患 者的血清IL-27 和PCT值,肺源性脓毒症患者的AUC为0.728,非肺源性脓毒症患者的AUC 为0.703。对肺源性脓毒症患者与非 肺源性脓毒症患者诊断的准确性均有所提升。结论:肺源性和非肺源性脓毒症患者较非脓毒症患者更加符合SIRS 标准。IL-27 作 为脓毒症诊断的生物标志物,对病情变化的反应不敏感,而IL-27 和PCT 结合可以使诊断的准确性提高。  相似文献   
692.
Abstract Chromosomal DNA fragments from Chlamydia trachomatis serotype L2 were shotgun-cloned into pBR322. A C. trachomatis -specific clone was further subcloned to produce specific DNA reagents for the identification of C. trachomatis by nucleic acid sandwich hybridization. The chosen DNA reagents from serotype L2 also hybridized with all the other chlamydial serotypes tested, but not with the DNA from 41 unrelated organisms. The sensitivity of the sandwich hybridization test was 106 DNA molecules. The applicability of the test for routine diagnostic use was demonstrated by a pilot study in which C. trachomatis was directly detected from genital specimens.  相似文献   
693.
ABSTRACT. We have surveyed 244 hemipterans from Western Brazilian Amazônia for the presence of trypanosomatids and identification of members of the genus Phytomonas. Examination by phase microscopy of squashes of insect salivary glands (SG) and digestive tubes (DT) revealed that 44% (108/244) of insects from seven families harbored trypanosomatids. Infections were 5 times more frequent in Coreidae than in all other families together. Smears of SG and DT of the dissected insects were fixed on glass slides with methanol and stained with Giemsa for morphological analysis. DNA was recovered from these preparations and submitted to a PCR assay that permitted amplification of all trypanosomatid genera using primers of conserved sequences flanking a segment of the spliced leader (SL) gene. Upon PCR amplification of the recovered DNA, amplicons were hybridized with an oligonucletide probe (SL3′) complementary to a SL intron sequence specific for flagellates of the genus Phytomonas. Among the trypanosomatid‐positive insects, 38.8% harbored Phytomonas spp., corresponding to an overall Phytomonas prevalence of 17.1% among phytophagous bugs, their putative vectors. Since many Phytomonas are pathogenic in plants, this high prevalence in their vectors emphasizes the permanent risk of exposure to disease by native and cultured plants of the Amazon region.  相似文献   
694.
Direct PCR analysis of trypanosome infected blood samples in the quantities required for large scale epidemiological study has always been problematic. Current methods for identifying and differentiating trypanosomes typically require several species-specific reactions, many of which rely on mouse passaged samples to obtain quality concentrated genomic DNA. As a consequence important epidemiological information may be lost during the sample preparation stage. Here, we report a PCR methodology that reduces processing and improves on the sensitivity of present screening methods. The PCR technique targets the gene encoding the small ribosomal subunit in order to identify and differentiate all clinically important African trypanosome species and some subspecies. The method is more economical, simple, and sensitive than current screening methods, and yields more detailed information, thereby making it a viable tool for large-scale epidemiological studies.  相似文献   
695.
Diagnosis of amebiasis is usually performed on a clinical basis alone in most endemic countries having limited economic resources. This epidemiological study was conducted using modern diagnostic tests for amebiasis in the southeastern region of Turkey, an endemic area for amebiasis. The population of this study included patients with symptomatic diarrhea/dysentery attending both Yuzuncu Yil University, Van and Harran University, Sanliurfa, Turkey. A total of 380 stool specimens were collected and examined for Entamoeba by light microscopy (fresh, lugol, and trichrome staining) and stool antigen detection based- enzyme-linked immunosorbent assay (EIA) test (TechLab Entamoeba histolytica II). 24% (91/380) of stool specimens were positive for E. histolytica/Entamoeba dispar trophozoites/cysts microscopically using trichrome staining. 13% (51/380) of the stool specimens were found to be positive for E. histolytica by the EIA test, including 15% (14/91) of microscopy (+) stool specimens and 13% (37/289) of microscopy (-) stool specimens. Enteric parasites were common in these populations with 66% (251/380) of the study population harboring more than one parasite. In addition to the 13% (51/380) of patients determined to have E. histolytica by EIA, eighty-six patients (22.6%) had Blastocystis hominis, 54 (14.2%) Entamoeba coli, 44 (11.5%) Giardia lamblia, 16 (4.2%) Chilomastix mesnili, 15 (3.9%) Iodamoeba bütschlii, 12 (3.1%) Hymenolepis nana, 9 (2.3%) Endolimax nana, 9 (2.3%) Dientamoeba fragilis, and 8 (2.1%) had Ascaris lumbricoides. We concluded that E. histolytica infection was found in 13% of the patients presenting with diarrhea in Van and Sanliurfa Turkey.  相似文献   
696.
697.
Recent advances in genomic technology have focused many veterinary researchers on the possibility of producing one multivalent recombinant vaccine against all the haemoparasites that infect cattle in the tropics. Before such a vaccine is developed it is essential to define target cattle populations as well as the range of anti-pathogen vaccines required in order to control disease. To further this objective, we have evaluated a reverse line blot (RLB) assay, which simultaneously detects the principal tick transmitted protozoan and rickettsial cattle pathogens, in different epidemiological scenarios in Uganda. A critical question is the sensitivity, particularly in relation to detecting carrier animals. As Theileria parva is considered to be the most important pathogen in the region, we assessed the sensitivity of the RLB assay for T. parva and showed that 1-2 x 10(3) parasites per ml of blood could be detected-a level comparable with previously developed PCR methods and well below conventional microscopic detection. We applied the RLB assay to evaluate the differences in pathogen profiles between crossbred and indigenous cattle and show that there were different profiles, with a low prevalence of T. parva and Theileria taurotragi in the indigenous cattle compared to a high prevalence in the crossbred cattle. In contrast, we show higher prevalences of Theileria mutans and Theileria velifera in the indigenous compared to the crossbred cattle. Interestingly Anaplasma marginale, Babesia bovis and Babesia bigemina were of low prevalence but a high prevalence of Ehrlichia bovis was seen, raising the question of whether this rickettsial species could be pathogenic in cattle. Analysis of animals with clinical symptoms of East Coast Fever showed that, while T. parva is a major cause of these symptoms, T. mutans and possibly T. taurotragi and T. velifera, may also cause clinical disease. Overall, the results presented here highlight the complexity of tick-borne pathogen infections in cattle in Uganda.  相似文献   
698.
At the Human Disease Glycomics/Proteome Initiative workshop held on August 27 on the occasion of the fourth HUPO Congress in Munich, Germany, the working groups reported on pilot studies, performed by 21 laboratories world-wide, to analyze glycan using MS. During the steering committee on July 31 in Osaka, Japan, it was reported that these groups have developed a system using MS to assess the world-wide network on the screening of congenital disorders of glycosylation. The concept of glycobioinformatics was also explained at this meeting. The session on PTMs laid particular emphasis on the importance of functional glycomics using glycosyltransferase genes as well as on the importance of identifying the target protein(s) carrying the sugar chains.  相似文献   
699.
Wang JX  Yu JK  Wang L  Liu QL  Zhang J  Zheng S 《Proteomics》2006,6(19):5344-5349
To find new biomarkers and establish serum protein fingerprint models for early diagnosis and preoperative staging of papillary thyroid carcinoma, we employed SELDI-TOF-MS and bioinformatics tools. A total of 116 samples were analyzed in this study. The first 80 samples were analyzed by SELDI-TOF-MS and two biomarker patterns were identified. Pattern 1 distinguishes patients with papillary thyroid carcinoma from healthy individuals. Pattern 2 distinguishes papillary thyroid carcinoma from benign thyroid nodes. The remaining 29 samples were analyzed on the second day and served as an independent test set. The analysis of this independent test set yielded a specificity of 80.0% and a sensitivity of 88.9% for pattern 1 and a specificity of 80.0% and a sensitivity of 80.0% for pattern 2. Two additional biomarker patterns were identified to distinguish different stages of the papillary thyroid carcinoma (pattern 3) with an accuracy of 77.1% and different pathological types of thyroid carcinoma (pattern 4) with an accuracy of 88.1%. Taken together, the SELDI-TOF-MS technique combined with bioinformatics approaches can not only facilitate the discovery of better biomarkers for papillary thyroid carcinoma but also provide a useful tool for molecular diagnosis in the future.  相似文献   
700.
目的:探讨血清miR-92a在胰腺癌诊断和预后分析中的价值,为胰腺癌早诊断以及预后评估提供潜在的分子标志物。方法:回顾性分析我院及重庆医科大学附属第一、第二医院2014年8月~2016年12月收治的30例胰腺癌未转移患者、30例胰腺癌转移患者和30例慢性胰腺炎患者的临床资料,另选择同期在我院进行健康体检的30例健康人作为健康组。收集血清,应用定量PCR法检测各组血清miR-92a的表达水平,利用化学发光法检测各组血清中的糖蛋白抗原19-9(CA-19-9)含量。以ROC分析比较血清miR-92a与CA 19-9在胰腺癌诊断中的特异度、敏感性。结果:胰腺癌未转移组患者和胰腺癌转移组患者血清中miR-92a水平显著高于健康组和慢性胰腺炎组(P0.05),胰腺癌转移组患者血清中miR-92a水平显著高于胰腺癌未转移组患者(P0.05)。胰腺癌未转移组患者和胰腺癌转移组患者血清中CA19-9水平显著高于健康组和慢性胰腺炎组(P0.05)。miR-92a诊断胰腺癌的敏感度高于CA19-9和miR-92a+CA 19-9,而miR-92a+CA 19-9诊断胰腺癌的特异度显著高于miR-92a和CA19-9(P0.05),且有较高的胰腺癌转移预测应用价值。结论:血清miR-92a联合CA 19-9检测能够诊断胰腺癌,具有良好的敏感度和特异度,miR-92a还具有较好的胰腺癌转移预测价值,可作为胰腺癌早期无创筛查方法加以应用。  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