全文获取类型
收费全文 | 2500856篇 |
免费 | 203025篇 |
国内免费 | 4769篇 |
专业分类
耳鼻咽喉 | 36047篇 |
儿科学 | 76300篇 |
妇产科学 | 65570篇 |
基础医学 | 351365篇 |
口腔科学 | 70226篇 |
临床医学 | 228272篇 |
内科学 | 494497篇 |
皮肤病学 | 50245篇 |
神经病学 | 213800篇 |
特种医学 | 100182篇 |
外国民族医学 | 895篇 |
外科学 | 378200篇 |
综合类 | 57999篇 |
现状与发展 | 4篇 |
一般理论 | 1157篇 |
预防医学 | 200541篇 |
眼科学 | 59117篇 |
药学 | 185610篇 |
4篇 | |
中国医学 | 4508篇 |
肿瘤学 | 134111篇 |
出版年
2018年 | 26460篇 |
2017年 | 20388篇 |
2016年 | 22517篇 |
2015年 | 25654篇 |
2014年 | 36970篇 |
2013年 | 56468篇 |
2012年 | 76538篇 |
2011年 | 80769篇 |
2010年 | 47179篇 |
2009年 | 45309篇 |
2008年 | 76752篇 |
2007年 | 81707篇 |
2006年 | 82205篇 |
2005年 | 80524篇 |
2004年 | 77608篇 |
2003年 | 74852篇 |
2002年 | 73812篇 |
2001年 | 113489篇 |
2000年 | 117330篇 |
1999年 | 99460篇 |
1998年 | 29558篇 |
1997年 | 26946篇 |
1996年 | 26683篇 |
1995年 | 25740篇 |
1994年 | 24165篇 |
1993年 | 22536篇 |
1992年 | 80104篇 |
1991年 | 77074篇 |
1990年 | 74156篇 |
1989年 | 71419篇 |
1988年 | 66433篇 |
1987年 | 65311篇 |
1986年 | 61936篇 |
1985年 | 59069篇 |
1984年 | 45112篇 |
1983年 | 38508篇 |
1982年 | 24095篇 |
1981年 | 21478篇 |
1980年 | 20111篇 |
1979年 | 41890篇 |
1978年 | 29681篇 |
1977年 | 24974篇 |
1976年 | 23381篇 |
1975年 | 24383篇 |
1974年 | 30110篇 |
1973年 | 28400篇 |
1972年 | 26526篇 |
1971年 | 24366篇 |
1970年 | 22942篇 |
1969年 | 21254篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
C Vaishnavi C Sokhey S Kaur B Kumar J B Dilawari N K Ganguly 《Indian journal of leprosy》1989,61(2):211-215
An ELISA technique has been developed to detect HBsAg in the sera of leprosy patients. Out of ninety-two serum samples taken from untreated leprosy patients, 10 samples were positive for HBsAg. The ELISA used in the present investigation is a low cost, reliable and sensitive marker of HBsAg. It is better than lesser sensitive (haemagglutination and counterimmunoelectrophoresis), costly and hazardous (radioimmunoassay) techniques and is therefore recommended for routine use. 相似文献
992.
993.
The authors report a case of massive Trichuris trichiura infection, resulting in severe anaemia and congestive cardiac failure in a 9-year-old Iban boy, who was resistant to the usual oral anthelmintic treatment, but promptly responded to mebendazole retention enema. This patient also had an associated Entamoeba histolytica infection. 相似文献
994.
The virD operon of Agrobacterium tumefaciens Ti plasmid encodes a DNA-relaxing enzyme. 总被引:15,自引:3,他引:12 下载免费PDF全文
J Ghai A Das 《Proceedings of the National Academy of Sciences of the United States of America》1989,86(9):3109-3113
The virD locus of Agrobacterium tumefaciens Ti plasmid encodes functions necessary for endonucleolytic cleavage of transferred DNA (T-DNA) prior to its transfer to plant cells. For the overproduction of the VIRD proteins in Escherichia coli a tac-virD operon fusion was constructed. A significant increase in the accumulation of VIRD proteins was observed in a lon protease-deficient E. coli host. The presence of an overlapping open reading frame (ORF) upstream of the VIRD1 coding sequence had a negative effect on VIRD1 production. A preparation containing VIRD proteins catalyzes the conversion of supercoiled (form I) DNA to relaxed (form IV) DNA. This activity is similar to that of a DNA topoisomerase. The relaxation activity lacks DNA sequence specificity, requires magnesium ion, and has no requirement for an energy source. Studies with plasmids that had lost defined DNA segments encompassing various virD coding regions showed that VIRD1 is the DNA-relaxing enzyme. In a density gradient centrifugation experiment, the DNA-relaxing activity sedimented as a 21-kDa polypeptide. Earlier studies of Jayaswal et al. [Jayaswal, R., Veluthambi, K., Gelvin, S. & Slightom, J. (1987) (J. Bacteriol. 169, 5035-5045] have shown that in E. coli VIRD2 alone is not sufficient for endonucleolytic cleavage of T-DNA and requires VIRD1 for its activity. 相似文献
995.
Peter J. Morgan Lynda M. Williams Gary Davidson Wilfred Lawson Edward Howell 《Journal of neuroendocrinology》1989,1(1):1-4
The functional significance of the pars tuberalis (PT) of the mammalian adenohypophysis has remained an enigma (1, 2). One view of its function is that it acts as an auxiliary gland to support the endocrine role of the pars distalis (PD) (2), as it has been shown to contain immunocytochemically identifiable thyrotrophs and gonadotrophs (1). Many of the cells of the PT are, however, ultrastructurally unique suggesting an independent function for this tissue. Our recent demonstration that the PT of the rat is a major binding site for the ligand iodomelatonin lends further support to this idea (3). We have utilized the highly specific ligand [125 l]melatonin, and have demonstrated that it binds exclusively, with very high affinity, to the PT but not the PD of the adult sheep adenohypophysis. These findings support the conclusion that the PT has a distinct role in relation to melatonin action and seasonal reproduction. 相似文献
996.
Histological sections of brain from patients showing evidence of advanced pathology of Alzheimer disease (AD) were examined for the presence of herpes simplex type-1 (HSV-1) nucleic acids by a sensitive in-situ hybridization technique. Samples from neurologically normal patients were examined in parallel. Sensitivity of the assay was verified by the detection of HSV-1 nucleic acids in neurons of trigeminal ganglia taken from cases of AD and normal controls. This indicated that the hybridization reaction was sufficiently sensitive to detect latent HSV-1 infections. Positive hybridization in the brain was only detected in a confirmed case of herpes simplex virus encephalitis. These results appear to confirm previous reports that HSV-1 infection is not directly involved in the pathology associated with AD. 相似文献
997.
998.
Concurrent positive serology for ehrlichiosis and Lyme disease 总被引:1,自引:0,他引:1
999.
J L Dubois-Randé D Loisance A M Duval-Moulin P Deleuze D Lellouche O Tavolaro L Hittinger C Benvenuti P Merlet D Brun 《Archives des maladies du coeur et des vaisseaux》1989,82(8):1433-1438
Enoximone is a positive inotropic agent belonging to the group of phosphodiesterase F-III inhibitors. The drug was tested in 34 patients uncontrolled by sympathomimetic drugs and referred to our department for urgent heart transplantation or circulatory assistance. After insertion of a Swan-Ganzgatheter and a radial artery catheter for haemodynamic monitoring, enoximone was administered as a 15-minute intravenous bolus injection of 1 to 2.5 mg/kf every 8 hours, in addition to sympathomimetic agents. Clinical and haemodynamic improvement was observed after thirty minutes in 30 patients. The cardiac index rose from 1.82 to 2.67 l/min/m2 and the pulmonary wedge pressure fell from 30.8 to 18.9 mmHg. Systemic arterial resistance decreased from 2170 to 1520 dyn. s. cm-5, and pulmonary resistance from 5.5 to 4.6 Wood units (p less than 0.01 for all values). Four patients had no haemodynamic improvement and were put on circulatory assistance, using a Jarvik 7 total artificial heart in 3 of them and heterotopic circulatory assistance in one. After clinical investigation for contra-indication to heart transplantation, and as their improved haemodynamic status permitted, 12 of the 30 patients were considered suitable (group B) for heart transplantation. Transplantation was performed within a week of admission in 11 patients without any need for mechanical assistance. One of the group B patients who required implantation of a Jarvik 7 artificial heart died after 12 hours of assistance. Eighteen patients were considered unsuitable for transplantation (group A) and treated medically.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
1000.
In a study of rock music preferences, listening/watching behavior, and views on destructive rock lyrics, 894 adolescents in grades 9 through 12 in rural, urban, suburban public, and metropolitan parochial schools were administered a questionnaire. Demographic information on parents was also collected. It was found that 17.5% of the students were fans of rock music with lyrics that promote homicide, suicide, or satanic practices (HSSR). Loglinear and multiple regression analyses were used to analyze the data. Parents' marital status, student sex, race, and school environment (urban, rural, suburban, etc.) were found to be significant predictors of HSSR status. As compared with non-HSSR fans, the HSSR fans were more likely to have parents who were “Never married” or “Remarried” and less likely to have parents in the “married” category. The HSSR fans were more likely to be male, white, and enrolled in urban schools but not parochial schools than expected; HSSR status also significantly predicted other music-related attitudes and behaviors. The HSSR fans reported liking both the sound and the lyrics of rock music more often than did non-HSSR fans, as did females and urban students. The HSSR fans more often felt that children under 10 years of age should be allowed to listen to HSSR lyrics, and they more frequently expressed the conviction that HSSR music does not affect adolescents' homicidal or self-destructive behavior. The HSSR fans and females reported more nearly complete knowledge of lyrics than did non-HSSR fans and males. The HSSR fans reported that they watch more MTV than did any other group except rural students. 相似文献