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   535篇
  免费   27篇
  国内免费   3篇
耳鼻咽喉   4篇
儿科学   19篇
妇产科学   3篇
基础医学   117篇
口腔科学   4篇
临床医学   32篇
内科学   109篇
皮肤病学   2篇
神经病学   66篇
特种医学   13篇
外科学   90篇
综合类   1篇
预防医学   28篇
眼科学   7篇
药学   33篇
肿瘤学   37篇
  2023年   5篇
  2022年   7篇
  2021年   21篇
  2020年   15篇
  2019年   11篇
  2018年   13篇
  2017年   11篇
  2016年   12篇
  2015年   19篇
  2014年   16篇
  2013年   25篇
  2012年   43篇
  2011年   47篇
  2010年   18篇
  2009年   13篇
  2008年   24篇
  2007年   36篇
  2006年   29篇
  2005年   37篇
  2004年   26篇
  2003年   27篇
  2002年   31篇
  2001年   5篇
  2000年   8篇
  1999年   5篇
  1998年   7篇
  1996年   2篇
  1994年   2篇
  1993年   2篇
  1991年   4篇
  1990年   5篇
  1989年   2篇
  1988年   6篇
  1987年   5篇
  1986年   2篇
  1985年   2篇
  1984年   2篇
  1981年   1篇
  1980年   2篇
  1979年   2篇
  1978年   2篇
  1977年   1篇
  1976年   1篇
  1975年   1篇
  1972年   1篇
  1970年   1篇
  1968年   2篇
  1967年   1篇
  1939年   1篇
  1905年   1篇
排序方式: 共有565条查询结果,搜索用时 546 毫秒
1.
乌克兰居民在切尔诺贝利核电站事故后的健康状况   总被引:1,自引:0,他引:1  
本文报告了切尔诺贝利事故后受到影响的乌克兰三个人群(救援人员、30km区域内撤离人员、儿童和少年)在1990~2004年间健康状况的观察结果.受害者的总人数有22.5万人.受照剂量在0.25~0.70Gy的救援人员有7 400人.观察的指标有随机性效应(甲状腺癌、白血病、妇女乳腺癌和其他恶性肿瘤的发病率)和确定性效应(急性放射病、白内障、非肿瘤性疾病,以及儿童和少年的健康状况),证明上述人群中这些效应的危险性有所增加.报告还分析了非照射因素在这些效应发生中所起的作用,说明这些疾病在发病原因上的多样性.  相似文献   
2.
An intravascular gas exchange device for the treatment of respiratory failure consisted of a multitude of blind-ended hollow fibers glued in a pine-needle arrangement to a central gas supply catheter. It has previously been shown that gas desorption rates can be significantly enhanced by cycling gas pressure between a hypobaric level of 130 and an ambient level of 775 Torr. In this study, influences of the cycling frequency (f) and the cycle fraction during which hypobaric pressure is applied () were investigated. Rates of O2 desorption from O2-saturated water and CO2 desorption from CO2-saturated water into a manifold containing 198 fibers, 380 m in diameter, were measured over a range of f from 0.2 to 1.0 Hz, from 0.1 to 0.8, and fiber lengths from 4 to 16 cm. Relative to operation at ambient pressure, pressure cycling increased O2 transfer 3–4 times and CO2 transfer 4–6 times when the water flowed over the fiber manifold at 2.3 l/min. Transfer rates were relatively insensitive to f and with 80–90% of maximum enhancement obtained when was as low as 0.2. Transfer rates increased continuously with fiber length, implying that pressure cycling reduced the intra-fiber resistance to gas diffusion. A mathematical diffusion model which utilized only two adjustable parameters, a mass transfer coefficient for O2 and for CO2, simulated the trends exhibited by desorption data. © 1998 Biomedical Engineering Society. PAC98: 8745Hw, 8790+y  相似文献   
3.
Nonstructural protein 3 (NS3) of human hepatitis C virus (HCV) is a conserved multi-functional protein essential for replication and translation of viral RNA and polyprotein processing. Early T-cell response against NS3 is capable of restricting viremia. We aimed at characterizing the immunogenicity in gene immunization of the conserved regions of NS3 critical for protein folding and activity. C57BL/6 mice were injected with NS3 gene of Russian HCV 1b isolate 274933RU. Immunization did not exert any overt histological changes and had no long-term effects on the immune status of NS3 gene-recipients. The immune response in NS3 gene-recipients was screened by antibody ELISA, T-cell proliferation test and immune assays for specific cytokine production. T-lymphocytes of NS3 gene-recipients proliferated in response to peptides representing conserved regions of protease and ATPase/helicase. Stimulated T-lymphocytes produced IL-2, and in response to protease-derived peptides, also IFN-gamma. Potent and long-lasting antibody response was raised against conserved NS3 regions including "Greek-key" motif of protease, motifs II, V and polynucleotide-binding domains of ATPase/helicase. Thus, gene immunization effectively targeted conserved regions critical for NS3 protease and helicase function. In type and specificity, immune response of NS3 gene-immunized mice mimicked immunity achieved in the acute self-limiting HCV infection of human and primates and in virus-exposed healthy individuals, indicating promiscuity of NS3 as immunogen.  相似文献   
4.
Anhydrotetracycline oxygenase was purified both by affinity chromatography and by hydrophobic interaction chromatography. Molecular weight of anhydrotetracycline oxygenase was determined to be 115,000 by Sephadex G-200 gel filtration. Using preparative isoelectric focusing the isoelectric point of the enzyme was estimated to be 5.3. The enzyme showed a sensitivity to thiol-specific inhibitors. During the hydrophobic interaction purification step, the activity dropped considerably. Reactivation occurred when a heat treated crude extract was added to the reaction mixture.  相似文献   
5.
n = 665, 51%) had an ISS ranging from 0 to 34 (mean 13) had wounds ranging from G1ST (soft tissue wounds caused by low energy transfer) to G3VF (massive wounds with fractures and injury of vital structures) according to the RCWC, with PSS/IS scores from 2 to 105 (mean 60). Statistically significant correlation was found between ISS and PSS/IS as well as RCWC and PSS/IS. Cytokines (IL-1, TNF alpha ) and amino acids responded to a blast injury in similar manner as to gunshot wounds with a greater ISS or more severe RCWC injury type. The subjective sensations in blasted patients (deafness, thoracic pain, vertigo) and mediators, confirmed in previous experimental investigations as important factors in the pathogenesis of blast injuries (TxA 2 , sulfidopeptide leukotrienes) were relationed only to the PSS/IS.RID=" ID=" <E5>Correspondence to:</E5> I. Cernak, M.D., Ph.D.  相似文献   
6.
We studied the influence of 10 synthetic glycoamine analogs on colony formation in 0.3 and 0.9% agarose by metastatic human breast carcinoma (MDA-MB-435) and melanoma (TXM-13) cells. Nine synthetic analogs significantly inhibited the colony formation in 0.9% agarose of MDA-MB-435 human breast carcinoma cells; five compounds caused a 73–83% reduction of colony formation. Seven synthetic glycoamines caused a significant inhibition of colony formation in 0.9% agarose by TXM-13 melanoma cells with the inhibitory effect ranging from 71 to 87%. The 50% inhibition (I50) doses and relative activity rank of the compounds were similar for both breast carcinoma and melanoma cell lines. The murine B16 melanoma cell aggregation assay was employed to elucidate the potential mechanism(s) of the inhibitory activity of synthetic glycoamines. The relative activity ranks of the compounds based on the independently determined I50 doses for both cell aggregation and clonogenic growth assays were very similar for the four most active synthetic analogs and clearly indicated the importance of hydrophobic amino acid in mediating the bioactivity of synthetic glycoamines. In both experimental systems (clonogenic growth in agarose and cell aggregation assay) the leading compound was N-(1-deoxy-d-fructos-1-y1)-d-leucine (Fru-d-Leu) and the least active analog was N-(1-deoxy-d-fructos-1-yl)-glycine (Fru-Gly). These results show that synthetic glycoamines may act by competing for specific carbohydrate-lectin interactions, particularly those involving -galactoside-specific lectins expressed on metastatic cells.  相似文献   
7.
A number of recent studies have shown avoidant coping to be related with diverse types of somatic and mental pathology. In order to investigate the relevance of coping for both psychological and somatic problems in delinquent subjects, 185 boys from juvenile correction and 96 boys from secondary schools in Arkhangelsk, Northern Russia, were assessed by means of the Coping Scale for Children and Youth, the Youth Self-Report and the Giessen Subjective Complaints List - youth form. The results from the delinquent subjects partly confirmed previous findings on the dominant role of behavioural avoidance in the relationships between coping styles and both behavior/emotional problems and somatic complaints. Further implications of the results are discussed.  相似文献   
8.
Two forms of complement-depleting cobra venom factor (CVFm1 and CVFm2), possessing molecular masses of 142.6 kDa (CVFm1) and 143.1 kDa (CVFm2), according to MALDI mass-spectrometry, were isolated from the Naja melanoleuca cobra venom. As shown by polyacrylamide gel electrophoresis in the presence of SDS, both forms similarly to factor from the Naja kaouthia cobra venom (CVFk) consist of three polypeptide chains with molecular masses of about 70, 50, and 30 kDa, the two large subunits being glycosylated. As determined by MALDI mass-spectrometry, 30 kDa subunits of CVFm1 and CVFm2 have considerably different finger-prints of tryptic digests that suggests differences in their amino acid sequences. A study of activity in vivo has shown no significant differences in C3 consumption by CVFm1, CVFm2 and CVFk in mouse blood. However, as shown by an immunoassay method, they differ in their ability to activate the complement system via C3 conversion, the ratio of these activities for CVFm1:CVFm2:CVFk being 2.5:1.6:1. Kinetic studies using a hemolytic test showed that complement depletion by CVFm1 is faster than that by CVFm2. Thus, for the first time the presence in a single venom of two forms of CVF differing by both amino acid sequence and biological activity has been shown.  相似文献   
9.
10.
BACKGROUND CONTEXTAnterior cervical discectomy and fusion is a common procedure for degenerative cervical radiculopathy. In 1996, Dr. H.D. Jho reported an operative technique allowing nerve root decompression via anterior uncoforaminotomy whereas avoiding fusion.PURPOSETo assess long-term clinical and radiological outcomes of anterior uncoforaminotomy in patients with degenerative cervical spine pathology.STUDY DESIGNA single clinic, retrospective cohort study.PATIENT SAMPLEAdult patients who underwent anterior uncoforaminotomy from 2013 to 2018.OUTCOME MEASURESClinical outcomes were assessed using VAS, NDI, SF-36 criteria. Radiological parameters included sagittal balance, disc height and White anPanjabi criterion.MATERIALS AND METHODSAll patients underwent unilateral single-level anterior uncoforaminotomy, and long-term clinical and radiologic follow up was carried out. Clinical outcomes were assessed using VAS, NDI, SF-36 criteria. Radiological parameters evaluated included sagittal balance, disc height and White and Panjabi criteria (3.5 mm of translation, 11 degrees of kyphosis). The mean follow-up period was 33.3 ± 10.6 months (range 12–57 months).RESULTSAll measures of clinical outcome improved. VAS (neck) and VAS (arm) decreased 3 [2; 4] and 5 [3; 5.2] points (median [interquartile range]), respectively (p<0.001); NDI improved from 0.38 [0.36; 0.4], to 0.29 [0.22; 0.34] (p<0.001). Two patients (6%) required additional surgery one year after operation. There were no complications in the perioperative period. Disc height decreased 0.8 mm [0.1; 2.1] (p<0.001). All patients retained stability of the cervical spine based on White and Panjabi criteria. Sagittal balance parameters did not change significantly.CONCLUSIONUncoforaminotomy is an effective and safe method to decompress a unilateral single-level nerve root in degenerative cervical radiculopathy whereas preserving anatomy and motion of the cervical spine.  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