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   33706篇
  免费   3303篇
  国内免费   646篇
耳鼻咽喉   153篇
儿科学   1269篇
妇产科学   802篇
基础医学   2481篇
口腔科学   338篇
临床医学   3499篇
内科学   7088篇
皮肤病学   429篇
神经病学   1832篇
特种医学   530篇
外科学   2891篇
综合类   3287篇
现状与发展   1篇
一般理论   12篇
预防医学   8736篇
眼科学   816篇
药学   1625篇
  3篇
中国医学   415篇
肿瘤学   1448篇
  2024年   73篇
  2023年   485篇
  2022年   358篇
  2021年   549篇
  2020年   514篇
  2019年   262篇
  2018年   859篇
  2017年   850篇
  2016年   896篇
  2015年   907篇
  2014年   877篇
  2013年   1190篇
  2012年   1677篇
  2011年   3175篇
  2010年   1713篇
  2009年   1270篇
  2008年   1788篇
  2007年   1697篇
  2006年   1509篇
  2005年   1712篇
  2004年   3117篇
  2003年   2823篇
  2002年   2023篇
  2001年   1603篇
  2000年   818篇
  1999年   797篇
  1998年   664篇
  1997年   598篇
  1996年   284篇
  1995年   267篇
  1994年   339篇
  1993年   316篇
  1992年   291篇
  1991年   220篇
  1990年   145篇
  1989年   127篇
  1988年   101篇
  1987年   84篇
  1986年   76篇
  1985年   50篇
  1984年   37篇
  1983年   30篇
  1982年   33篇
  1981年   29篇
  1980年   20篇
  1979年   28篇
  1978年   25篇
  1977年   19篇
  1974年   28篇
  1968年   20篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
71.
Among a total of 101 isolates from the first systematic multicentre surveillance effort concerning invasive Streptococcus pyogenes disease in Greece, conducted between 2003 and 2005 and covering 38% of the population, emm types 1 and 12 were prevalent, being responsible for 27 and nine cases, respectively. The isolates from the remaining 65 cases were assigned to 26 other emm types. Erythromycin resistance (12 isolates) was primarily mef (A)-mediated, although all emm type 1 strains were susceptible. Tetracycline resistance, due mostly to tet (M), was detected in 26 isolates. Subtyping by pulsed-field gel electrophoresis yielded 50 chromosomal fingerprints, thus discriminating further among ten of the 28 observed emm types.  相似文献   
72.
硝苯啶、硫氮(艹卓)酮对兔实验性动脉粥样硬化症的影响   总被引:1,自引:0,他引:1  
硝苯啶和硫氮(艹桌)酮不明显影响血清脂蛋白组分水平,但均显著抑制家兔主动脉动脉粥样硬化形成,降低血浆过氧化脂质、血栓烷和主动脉内中膜胆固醇、磷脂及钙含量,升高血浆6-酮-PGF_(1α),使,TXB_2/6-酮-PGF_(1α)趋于平衡。说明钙在血栓烷-前列环素代谢中起重要作用。  相似文献   
73.
74.
75.
We have constructed cDNA microarrays from the human testis large insert cDNA library, containing 9216 genes, together with several housekeeping genes. The cDNA microarrays were used to identify gene expression differences between human fetal and adult testes. Of >8700 hybridized clones, 731 exhibited significant differential expression characteristics. About 7500 genes were identified when the same cDNA microarrays were used for hybridization with cDNA probes from mouse testis, with 256 genes having significant differential expression between the age of 1-4 weeks. Among these genes, 101 were identified as critically related to testis development and possibly to spermatogenesis since they were found in both human and mouse testes, and expressed differentially at different stages of testis development. Of the 101 development-related genes, 59 full-length cDNAs have been sequenced previously, while the full-length cDNAs of the other 42 genes have not been published. We have obtained 11 full-length sequences of the 42 genes and deposited them in the GenBank. The conserved testis development-related genes found in both human and mouse testes may include genes that are likely to be involved in testicular functions, especially spermatogenesis, thus providing a basis for further functional characterization of the genes in mouse models.  相似文献   
76.
A questionnaire-based retrospective clinical and immunological survey was conducted in 73 males with a definite diagnosis of X-linked agammaglobulinemia based on BTK sequence analysis. Forty-four were sporadic and 29 familial cases. At December 2000, the patients' ages ranged from 2 to 33 years; mean age at diagnosis and mean duration of follow-up were 3.5 and 10 years respectively. After the mid-1980s all but 2 were on intravenous immunoglobulin (IVIG) substitution therapy, with residual IgG >500 mg/dl in 94% of the patients at the time of enrollment. Respiratory infections were the most frequent manifestation both prior to diagnosis and over follow-up. Chronic lung disease (CLD) was present in 24 patients, in 15 already at diagnosis and in 9 more by 2000. The cumulative risk to present at diagnosis with CLD increased from 0.17 to 0.40 and 0.78 when the diagnosis was made at the ages of 5, 10, and 15 years respectively. For the 9 patients who developed CLD during follow-up, the duration of follow-up, rather than age at diagnosis; previous administration of intramuscular immunoglobulin; and residual IgG levels had a significant effect on the development of CLD. Chronic sinusitis was present in 35 patients (48%), in 15 already at diagnosis and in 20 by 2000. Sistemic infections such as sepsis and meningitis/meningoencephalitis decreased over follow-up, probably due to optimal protection provided by high circulating IgG levels reached with IVIG.  相似文献   
77.
78.
本文采用整群抽样的方法,对湖南两地区城乡共2377人(15岁以上)的成瘾物质使用状况进行调查,其中男1179(49.6%)人,女1199(50.4%人),平均年龄男女分别为41.2(SD=17.5)和43.4(SD=18.6)。结果表明,饮酒率男性为57.5%,女性为17.3%,吸烟率男女分别为68.2%和11.7%;饮酒者多集中在每月饮1次左右的人群中(男57.9%,女77.9%),但吸烟者多集中在每日吸20支及以上(男52.4%,女42.9%)的人群中。除解热镇痛剂外,男性各种精神活性物质的使用频率及剂量皆男高于女性,开始使用的年龄及成瘾的年龄男性低于女性;性别、使用频度、最早使用的年龄、婚姻与饮酒、吸烟量关系最为密切。有14人使用过鸦片类物质,4人使用过兴奋剂。作者讨论了我国成瘾物质使用的特点,指出经济水平、社会文化背景等因素与我国社会性成瘾物质的使用有密切关系。  相似文献   
79.
80.
Efficacy and safety of recombinant human activated protein C for severe sepsis   总被引:168,自引:0,他引:168  
BACKGROUND: Drotrecogin alfa (activated), or recombinant human activated protein C, has antithrombotic, antiinflammatory, and profibrinolytic properties. In a previous study, drotrecogin alfa activated produced dose-dependent reductions in the levels of markers of coagulation and inflammation in patients with severe sepsis. In this phase 3 trial, we assessed whether treatment with drotrecogin alfa activated reduced the rate of death from any cause among patients with severe sepsis. METHODS: We conducted a randomized, double-blind, placebo-controlled, multicenter trial. Patients with systemic inflammation and organ failure due to acute infection were enrolled and assigned to receive an intravenous infusion of either placebo or drotrecogin alfa activated (24 microg per kilogram of body weight per hour) for a total duration of 96 hours. The prospectively defined primary end point was death from any cause and was assessed 28 days after the start of the infusion. Patients were monitored for adverse events; changes in vital signs, laboratory variables, and the results of microbiologic cultures; and the development of neutralizing antibodies against activated protein C. RESULTS: A total of 1690 randomized patients were treated (840 in the placebo group and 850 in the drotrecogin alfa activated group). The mortality rate was 30.8 percent in the placebo group and 24.7 percent in the drotrecogin alfa activated group. On the basis of the prospectively defined primary analysis, treatment with drotrecogin alfa activated was associated with a reduction in the relative risk of death of 19.4 percent (95 percent confidence interval, 6.6 to 30.5) and an absolute reduction in the risk of death of 6.1 percent (P=0.005). The incidence of serious bleeding was higher in the drotrecogin alfa activated group than in the placebo group (3.5 percent vs. 2.0 percent, P=0.06). CONCLUSIONS: Treatment with drotrecogin alfa activated significantly reduces mortality in patients with severe sepsis and may be associated with an increased risk of bleeding.  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