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   26910篇
  免费   1227篇
  国内免费   68篇
耳鼻咽喉   363篇
儿科学   841篇
妇产科学   657篇
基础医学   3493篇
口腔科学   793篇
临床医学   2116篇
内科学   4835篇
皮肤病学   518篇
神经病学   2433篇
特种医学   939篇
外国民族医学   1篇
外科学   4032篇
综合类   89篇
一般理论   8篇
预防医学   2912篇
眼科学   582篇
药学   1911篇
中国医学   90篇
肿瘤学   1592篇
  2023年   173篇
  2022年   214篇
  2021年   448篇
  2020年   304篇
  2019年   391篇
  2018年   628篇
  2017年   511篇
  2016年   608篇
  2015年   665篇
  2014年   738篇
  2013年   1054篇
  2012年   1481篇
  2011年   1655篇
  2010年   853篇
  2009年   688篇
  2008年   1180篇
  2007年   1377篇
  2006年   1209篇
  2005年   1299篇
  2004年   1268篇
  2003年   1209篇
  2002年   1107篇
  2001年   658篇
  2000年   679篇
  1999年   578篇
  1998年   190篇
  1997年   168篇
  1996年   141篇
  1992年   353篇
  1991年   324篇
  1990年   348篇
  1989年   326篇
  1988年   307篇
  1987年   296篇
  1986年   317篇
  1985年   317篇
  1984年   245篇
  1983年   211篇
  1979年   247篇
  1978年   164篇
  1975年   157篇
  1974年   198篇
  1973年   199篇
  1972年   212篇
  1971年   175篇
  1970年   151篇
  1969年   194篇
  1968年   169篇
  1967年   159篇
  1966年   144篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Summary The presence of verotoxin-producing strains ofEscherichia coli (VTEC) was examined in six children with haemolytic uraemic syndrome and one child with haemorrhagic colitis. Stools were screened for strains of serogroup O157 on sorbitol-MacConkey agar for VTEC of other serogroups by serotyping. Verotoxin (VT) was tested on Vero cell monolayers: the antigenic variant of VT was assessed by neutralization experiments. Strains producing verotoxin 1 or verotoxin 2 or both were detected in the stools of all seven children. Three strains belonged to serogroup O157 (two of them to serotype O157:H7, one was non-motile) and another five belonged to serogroups O26 (two strains), O1, O5 and O18. The faeces of five children available for testing contained free VT. Production of VT was also examined retrospectively in 32E. coli strains of serotype O26:H11 isolated from children with diarrhoea; eight (25%) of them produced moderate to high levels of verotoxin 1 despite several years storagein vitro. In conclusion, VTEC including strains of serogroup O157 seem to be an important cause of haemolytic uraemic syndrome, haemorrhagic colitis and diarrhoea in children in Czechoslovakia.r>
Vero Cytotoxin bildende Stämme von Escherichia coli bei Kindern mit hämolytisch-urämischem Syndrom und Diarrhoe in der Tschechoslowakei
Zusammenfassung Bei sechs Kindern mit hämolytisch-urämischem Syndrom und einem Kind mit hämorrhagischer Kolitis wurde nach Verotoxin bildenden Stämmen vonEscherichia coli (VTEC) gesucht. Das Stuhl-Screening auf Stämme derSerogruppe O157 erfolgte auf Sorbitol-MacConkey Agar; zum Nachweis von VTEC und anderen Serogruppen wurde die Serotypisierung eingesetzt. Verotoxin (VT) wurde auf Monolayer-Verozellkulturen nachgewiesen; die Bestimmung der Antigenvariante von VT erfolgte durch Neutralisationsversuche. Bei allen sieben Kindern konnten im Stuhl Stämme nachgewiesen werden, die Verotoxin 1 oder Verotoxin 2 bildeten. Drei Stämme gehörten der Serogruppe O157 an (zwei davon Serotyp O157:H7, einer war ohne Motilität) und die übrigen fünf gehörten zu den Serogruppen O26 (zwei Stämme), O1, O5 und O18. Freies VT konnte in fünf Stühlen nachgewiesen werden; diese Untersuchung war nur bei fünf Kindern durchführbar. 32E. coli-Stämme vom Serotyp O26:H11, Isolate von Kindern mit Diarrhoe, wurden retrospektiv ebenfalls auf Bildung von VT untersucht. Davon bildeten achtin vitro (25%) noch mittel- bis hohe Spiegel von Verotoxin 1 obwohl sie schon mehrere Jahre lang gelagert waren. VTEC einschließlich der Stämme der Serogruppe O157 stellen folglich wichtige Erreger des hämolytischurämischen Syndroms, der hämorrhagischen Kolitis und anderer Formen der Diarrhoe bei Kindern in der Tschechoslowakei dar.
  相似文献   
992.

Objectives

The aim of the study was to survey the prevalence of human hantavirus infections among forestry workers, who are considered a risk population for contracting the disease. Sera collected from volunteers were tested for antibodies against Dobrava-Belgrade (DOBV) and Puumala (PUUV) viruses.

Material and Methods

For serological analyses, full capsid proteins of DOBV and PUUV viruses were produced in a bacterial expression system, while Ni-resin was used for protein purification. Samples were screened for anti-hantavirus antibodies by ref='/search?dc.title=ELISA&facet-content-type=ReferenceWorkEntry&sortOrder=relevance' class='reference-link webtrekk-track' gaCategory="Internal link" gaLabel="ELISA" gaAction="reference keyword">ELISA, results were confirmed by Western blot analysis.

Results

A total of 835 samples collected from 750 males and 85 females were tested by indirect ref='/search?dc.title=ELISA&facet-content-type=ReferenceWorkEntry&sortOrder=relevance' class='reference-link webtrekk-track' gaCategory="Internal link" gaLabel="ELISA" gaAction="reference keyword">ELISA and positive test results were confirmed by Western blot assay. Out of the 45 ref='/search?dc.title=ELISA&facet-content-type=ReferenceWorkEntry&sortOrder=relevance' class='reference-link webtrekk-track' gaCategory="Internal link" gaLabel="ELISA" gaAction="reference keyword">ELISA-reactive samples, 38 were confirmed by Western blot analysis. The regional distribution of seropositive individuals was as follows: 1.9% (2/107) in the Danube-Tisza Plateau (Great Plains), 3.1% (10/321) in the Southern Transdanubian region, 5.2% (13/248) in the Northern Transdanubian, and 8.2% (13/159) in the North Hungarian Mountains.

Conclusions

Our data show marked geographic differences in seroprevalence of pathogenic hantaviruses within Hungary, indicating elevated exposure to hantavirus infections in some areas.  相似文献   
993.
Recent research on problem-based learning (PBL) has shown that students need support when dealing with conflicting ideas in PBL-tutorial discussions. In the present study, we examined tutor facilitation during tutorial discussions, and particularly how the facilitation helped students to collaboratively resolve conflicts on knowledge. The study involved four PBL-tutorial sessions that included altogether 33 first-year medical and dental students. The sessions were videotaped and analysed using qualitative interaction analysis. Our aim was to find out how the tutor interventions encouraged students to elaborate on conflicting ideas, and how the interventions differed between conflict and non-conflict situations. We also examined how the tutors intervened during conflicts about factual or conceptual knowledge. The tutorial discussions included 92 tutor intervention episodes and 43 conflict episodes. The tutors intervened during 24 of the conflict episodes and resolved 13 of these episodes. Generally, the tutors often intervened by confirming what the students had said or by giving explanations, but they rarely asked questions that would stimulate the elaboration of knowledge. During conflicts on knowledge the tutors gave more explanations, but did little to encourage the students to deal with conflicting ideas. The tutors more often resolved conflicts on factual knowledge than conceptual knowledge. The findings suggest that tutor training should focus on promoting tutors’ understanding on when to give direct explanations, and when and how to encourage students to collaboratively elaborate on conflicting ideas.  相似文献   
994.

Objectives

The purpose of the study is to evaluate the effectiveness of toilet hygiene education in secondary school students.

Methods

The study was quasi-experimental with a pre-test–post-test design and includes a control group. The study was conducted at a secondary school in Istanbul, Turkey with 100 students (50 students for experiment and 50 students for control). The experiment and control groups were in the same school population. Data were collected with the student information form and toilet hygiene evaluation form (THEF), which were developed by the researchers.

Results

When we examined the toilet hygiene techniques used by the students, they indicated 58 % (n = 58) wiped perinea from front to back, 25 % (n = 25) back to front and 17 % (n = 17) randomly. It was found that 69 % (n = 69) of the students changed their underwear every 2–3 days; 80 % (n = 80) were trained by parents on toilet hygiene. Total THEF scores, which were obtained pre and post (shortly after) education, showed significant differences in the experiment group (p = 0.000). Total THEF scores obtained post education (shortly after and 1 month later) showed significant differences in the experiment group (p = 0.009).

Conclusions

The toilet hygiene education program is found to be successful in secondary school students.  相似文献   
995.
996.

Background:

In subungual exostosis surgery, repair of the damaged nail bed and surgical excision of the mass without damaging the nail bed is important. The ideal method of surgery is still unclear. This study is done to qualify the effects of different surgical methods on outcome measures in different types of subungual exostosis.

Materials and Methods:

Fifteen patients, operated with a diagnosis of subungual exostosis between January 2008 and June 2012, were evaluated. Protruded masses were excised with a dorsal surgical approach after the removal of the nail bed and nonprotruded masses were excised through a“fish-mouth” type of incision.

Results:

The mean age of the patients in protruded subungual exostosis group was 17.3 years (range 13-22 years) and this group consisting of seven female and two male patients. The patients were followed up for a mean of 14.1 ± 4.8 months. The mean age of the patients in the nonprotruded subungual exostosis group was 14.6 years (range 13-16 years) and consisting of six female patients. The patients were followed up for a mean of 11.6 ± 2.9 months. The results were positively affected by changing the surgical approach depending on whether or not the exostosis is protruded from the nail bed. All patients had healthy toe nails in the postoperative period without any signs of recurrence.

Conclusions:

In patients with a protruded subungual exostosis, the mass should be removed by a dorsal approach with the removal of the nail and injury to the nail bed should be repaired. In patients with a nonprotruded subungual exostosis, the mass should be excised through a “fish-mouth” type incision at the toe tip without an iatrogenic damage.  相似文献   
997.
998.
999.
1000.
IntroductionThe diagnostic approach to patients with isolated asymptomatic cervical lymphadenopathy varies between excisional biopsy and follow-up. When the anamnesis, physical examination, laboratory and imaging findings are not sufficient to identify the etiology, an excisional biopsy is performed for the differential diagnosis between early-stage lymphoma and infectious or reactive causes. If the excisional biopsy, which may have some complications, is not performed, it may delay the diagnosis of lymphoma. This diagnostic challenge could be avoided by predictive markers.ObjectivesThis study was planned to determine the predictive value of neutrophil/lymphocyte ratio in the diagnosis of Hodgkin and non-Hodgkin limphoma in patients with asymptomatic, isolated cervical limphadenopathy and underwent excisional biopsy.MethodsA total of 90 patients between the years 2016 ? 2019 admitted to our clinics due to asymptomatic isolated cervical lymphadenopathy, present in at least 4 weeks with lympho nodes in pathological dimensions persisting in the cervical region, were included to our study. An excisional lympho node biopsy was performed in all 90 patients.ResultsOf the 90 patients who underwent excisional biopsy; 34 were diagnosed as reactive lymphadenopathy 30 were non-Hodgkin linphoma, and 26 were Hodgkin linphoma. A total of 56 (62.2%) patients were diagnosed as lymphoma, either Hodgkin or non-Hodgkin, while 34 patients (38.8%) were diagnosed as reactive lymphadenopathy. The median age, total whiteblood count, neutrophil count of the lymphoma groups were significantly higher than reactive lymphadenopathy group, whereas the lymphocyte count was significantly lower in the lymphoma patients. The median neutrophil/ lymphocyte ratio was 1.7 in the reactive lymphadenopathy group, 3.5 in the non-Hodgkin limphoma group, and 3.0 in the Hodgkin limphoma group (p <  0.001).ConclusionAccording to the results of our study, neutrophil/lymphocyte ratio was significantly higher in patients who were admitted with isolated asymptomatic lymphadenopathy and were diagnosed with lymphoma, and who were diagnosed with early-stage Hodgkin and non- Hodgkin lymphoma compared to those who were found to have reactive lymphadenopathy. Neutrophil/lymphocyte ratio, which is a low-cost, fast and easy-to-access test, has a predictive value in the diagnosis of lymphoma in patients with asymptomatic lymphadenopathy.  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