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   6488篇
  免费   843篇
  国内免费   3篇
耳鼻咽喉   30篇
儿科学   261篇
妇产科学   147篇
基础医学   936篇
口腔科学   49篇
临床医学   826篇
内科学   1103篇
皮肤病学   450篇
神经病学   552篇
特种医学   313篇
外科学   788篇
综合类   183篇
一般理论   19篇
预防医学   717篇
眼科学   104篇
药学   500篇
中国医学   21篇
肿瘤学   335篇
  2021年   69篇
  2019年   86篇
  2018年   98篇
  2017年   72篇
  2016年   64篇
  2015年   77篇
  2014年   100篇
  2013年   178篇
  2012年   280篇
  2011年   276篇
  2010年   118篇
  2009年   153篇
  2008年   243篇
  2007年   300篇
  2006年   255篇
  2005年   242篇
  2004年   239篇
  2003年   252篇
  2002年   238篇
  2001年   238篇
  2000年   245篇
  1999年   238篇
  1998年   97篇
  1997年   84篇
  1996年   72篇
  1995年   97篇
  1994年   71篇
  1993年   81篇
  1992年   170篇
  1991年   165篇
  1990年   167篇
  1989年   168篇
  1988年   144篇
  1987年   153篇
  1986年   130篇
  1985年   137篇
  1984年   101篇
  1983年   108篇
  1982年   70篇
  1981年   55篇
  1980年   61篇
  1979年   131篇
  1978年   90篇
  1977年   68篇
  1976年   78篇
  1975年   70篇
  1974年   64篇
  1973年   72篇
  1972年   60篇
  1969年   62篇
排序方式: 共有7334条查询结果,搜索用时 0 毫秒
41.
Seventy three infants who underwent neonatal anatomical correction for transposition of the great arteries with or without a ventricular septal defect were reviewed for evidence of conduction and rhythm abnormalities on preoperative and postoperative 12 lead electrocardiograms and during 24 hour Holter monitoring. There was a partial right bundle branch block pattern in 47% (29/62) of all patients and in 60% (24/40) of those with simple transposition. Complete right bundle branch block was noted in 21% including 5% with simple transposition. Holter monitoring showed sinus rhythm in all patients except three: one had episodes of supraventricular tachycardia, another an intermittent second degree heart block, and a third a complete heart block. Atrial extrasystoles were noted in 47% (29/62) of patients but were frequent in only three patients. Occasional unifocal ventricular extrasystoles were encountered in 37% (23/62) of patients and were frequent in a further 3% (2/62). Only one patient (2%) developed multifocal ventricular extrasystoles. The frequency of important cardiac arrhythmias after neonatal anatomical correction of transposition of the great arteries was 5%, significantly less than that reported after atrial inflow diversion for the same malformation.  相似文献   
42.
43.
44.
This paper raises a number of issues in the assessment of quality of provision for pre-school children before comparing the quality of provision offered by community nurseries to that offered by traditional nursery schools. Quality at all locations was assessed using the Harms and Clifford Early Childhood Rating Scale and was found in each case to be at the good to excellent end of the range. Quality varied over time and between locations although all showed improvements by the third and final rating. It is possible to conclude that the community nursery model can provide an environment of comparable quality to that experienced in traditional nursery schools. It was also possible to conclude that quality is vulnerable to internal and external pressures and that monitoring quality can also have the effect of promoting quality when staff are able to respond to feedback from ratings.  相似文献   
45.
46.
BACKGROUND: The British Journal of General Practice (BJGP) is the leading primary care journal in the world. By impact factor, it ranks 24th of all medical journals. However, despite major changes in the journal since its inception in 1954, there have been no published readership surveys since a limited report in 1969. AIM: To canvass members of the Midland Faculty and to add to the debate about the future of the BJGP. METHOD: A postal questionnaire was sent to a random sample of 299 members, fellows and associates of the Midland Faculty asking for their views about the BJGP. RESULTS: Two hundred replies were received (a response rate of 67%). The median year of qualification of responders was 1981, and 32 (16%) held academic posts. Ninety-nine (49%) disagreed with the present format of the BJGP, which compared poorly with the British Medical Journal (BMJ) in simple rank order of importance. Readership was equal to that of the BMJ (93% reading it within 28 days of arrival), but fewer people read it within a week of receiving it. The most popular sections were the editorials, original articles and letters; least popular were the book reviews and the pull-out magazine, Connection. All sections were rated excellent to average. Readers wished for an expansion of the BJGP to include clinical reviews, medical politics and humorous pieces. Most responders felt that Connection should remain separate. There was dissatisfaction with the delay between submission and publication of original articles, particularly among the academic general practitioners (GPs). Academics and fundholders did not differ from other readers in their views of the content or style of the BJGP. Half of the responders stated that the BJGP should be self-financing and should be open to more advertising. Responders' free comments largely related to improving the style of articles and expanding the BJGP. CONCLUSION: There is a view that the present BJGP is not relevant to the non-academic GP. This is probably due to style rather than content. Simple comparisons with a weekly multi-disciplinary journal may not be valid. The style could be updated to improve retention of information and to highlight areas of particular relevance. Readers are satisfied with the core content of the BJGP but want it to expand to include humour, clinical reviews and medical politics, for example. There is no evidence that the BJGP is more appealing to the academic GP. This study supports an expanded BJGP with an improved style.  相似文献   
47.
In search of genes possibly involved in the regulation of hindbrain segmentation, we have isolated mouse cDNA clones corresponding to putative protein kinase genes by polymerase chain reaction amplification of cDNA from 9.5-day-old embryo hindbrains. In situ hybridization analysis revealed that one of these genes, Sek, was expressed in an alternating segment-restricted pattern in the developing hindbrain. Isolation and analysis of Sek cDNAs covering the entire coding sequence indicated that Sek encoded a putative receptor protein tyrosine kinase, belonging to the Eph family. These data are consistent with a role of the Sek gene product in a signal transduction process involved in pattern formation in the hindbrain.  相似文献   
48.
49.
Summary This paper reports the 8-year results of comparing the use of two types of adjuvant chemotherapy following involved field radiotherapy for clinical stages I and II high-grade non-Hodgkin's lymphoma. Twenty-four patients received 6 weeks of VAP plus 2 years of oral maintenance chemotherapy, and 30 had six cycles of CMOPP. Four patients were not in complete remission at completion of i. v. chemotherapy (CR rate 91%). Ten patients (18.5%) have relapsed (VAP/M=5; CMOPP=5), with only two of these remaining alive, both of them being disease free. There have been three deaths from intercurrent causes, one from malignant melanoma and the other two from myocardial infarction. The relapse-free survivals at 2, 5 and 8 years were 80%, 76% & 76% respectively. The overall survivals at the same time points were 86%, 72% & 68%. There were no significant differences in either relapse-free or overall survival for either of the two treatment groups. The shorter period of weekly intravenous chemotherapy (VAP/M) was better tolerated than 36 weeks of CMOPP, and the former appears to produce equivalent results.  相似文献   
50.
We showed previously that a commercially available synthetic tetradecapeptide, Asp-Arg-Val-Tyr-Ile-His-Pro-Phe-His-Leu-Leu-Val-Tyr-Ser, produces authentic angiotensin I (Ang I) upon incubation with the HIV-1 protease (S. K. Sharma et al., Anal. Biochem. 198:363, 1991). Therefore, we developed an Ang-I based activity assay for HIV protease inhibitors based on the technology developed earlier (M. J. Ruwart et al., Pharm. Res. 7:407, 1990; S. K. Sharma et al., Anal. Biochem. 186:24, 1990) for tracking renin inhibitors in rat sera. Ditekiren was either extracted from sera with ethyl acetate or assayed after the interfering substances in sera were precipitated with acetonitrile. Purified recombinant HIV-1 protease was added to extracted rat serum and the enzymatic reaction was initiated in the presence of the tetradecapeptide substrate. The inhibition of Ang I production was measured by a commercially available RIA kit. The cleanup methodology also enabled a commercially available Proteinase Scintillation Proximity Assay (SPA, Amersham) to quantify ditekiren in rat serum through the addition of recombinant HIV-1 protease and cleavage of substrate from SPA beads. Results were confirmed by HPLC or by the renin assay for ditekiren, which inhibits both aspartyl proteases. These technologies should prove useful for assessing serum levels of HIV protease inhibitors in rat.  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