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   1267731篇
  免费   95222篇
  国内免费   1594篇
耳鼻咽喉   16359篇
儿科学   41138篇
妇产科学   35077篇
基础医学   189882篇
口腔科学   34792篇
临床医学   118026篇
内科学   248708篇
皮肤病学   27358篇
神经病学   102207篇
特种医学   46837篇
外国民族医学   265篇
外科学   179430篇
综合类   25795篇
现状与发展   3篇
一般理论   570篇
预防医学   104972篇
眼科学   28135篇
药学   92790篇
  8篇
中国医学   2051篇
肿瘤学   70144篇
  2018年   13649篇
  2017年   10491篇
  2016年   11428篇
  2015年   13174篇
  2014年   18112篇
  2013年   27626篇
  2012年   37787篇
  2011年   40220篇
  2010年   23200篇
  2009年   22370篇
  2008年   37953篇
  2007年   40610篇
  2006年   40150篇
  2005年   39292篇
  2004年   37703篇
  2003年   36120篇
  2002年   35023篇
  2001年   56135篇
  2000年   57183篇
  1999年   48195篇
  1998年   13430篇
  1997年   12253篇
  1996年   12664篇
  1995年   11947篇
  1994年   11129篇
  1993年   10414篇
  1992年   38268篇
  1991年   37732篇
  1990年   36487篇
  1989年   35307篇
  1988年   32721篇
  1987年   32068篇
  1986年   30561篇
  1985年   28813篇
  1984年   21971篇
  1983年   19214篇
  1982年   11381篇
  1981年   10340篇
  1979年   20957篇
  1978年   15403篇
  1977年   12801篇
  1976年   11853篇
  1975年   12825篇
  1974年   15597篇
  1973年   15385篇
  1972年   14526篇
  1971年   13565篇
  1970年   12793篇
  1969年   12070篇
  1968年   11233篇
排序方式: 共有10000条查询结果,搜索用时 10 毫秒
941.
Colchicine is used for the treatment of various diseases including gouty arthritis, familial Mediterranean fever (FMF) and Behcet's disease. As a modulator of the microtubules at the cytoskeleton level, it arrests cell division at metaphase and inhibits microtubular- dependent cell motility. Controversy exists as to the adverse effect of colchicine on sperm production and function in healthy subjects as well as in gout, FMF and Behcet's patients. Sperm analysis shows a spectrum of pathology, from oligo- and azoospermia to normospermia with disturbances in sperm motility. These inconsistent sperm pathologies can be explained in part by the variability of the pathophysiology of the underlying disease. Thus, it seems that colchicine by itself may not have a significant direct adverse effect on sperm production and function.   相似文献   
942.
Duchenne and Becker muscular dystrophies are among the most severe and frequent inherited disorders. Being still incurable, medical treatment is concentrated on the carrier diagnosis of the members of the affected families. Here we report the results of the studies of 151 members of 41 Hungarian families, obtained with multiplex PCR amplification of 18 exons as well as the muscle specific promoter region, and haplotype analysis of two polymorphic (CA)n repeat microsatellite loci in introns 45 and 49 of the dystrophin gene. The analysis of 15 deletion-type families revealed a frequency of new mutations not differing significantly from that in the other regions of Europe. We also compared the allele distributions of the two microsatellites in randomly selected normal individuals and affected family members. The allele distribution of STRP45 shows interesting differences between the two populations.  相似文献   
943.
OBJECTIVE: Our purpose was to assess whether legislative action influenced the role of obstetrician-gynecologists as primary care physicians. STUDY DESIGN: An observational study was performed on the basis of a questionnaire sent to 410 obstetrician-gynecologists and 27 medical directors of managed-care organizations. RESULTS: Of 67% of obstetrician-gynecologists and 96% of medical directors who responded, there was agreement as to the content of primary care, but a minority (38%) of obstetrician-gynecologists identified themselves as primary care providers. A minority of medical directors (35%) felt that obstetrician-gynecologists should serve in that role. Both obstetrician-gynecologists and medical directors felt that legislation had little impact. CONCLUSION: The reticence of obstetrician-gynecologists to assume a major role in primary care appears to be the result of an uneasiness with accepting a more comprehensive role in patient management and gatekeeping. They appear comfortable with the more traditional roles but feel that training and experience has not prepared them well for the management of more complex medical problems. (Am J Obstet Gynecol 1998;178:1222-8.)  相似文献   
944.
Abstract Caries experience and enamel fluorosis prevalence in 8-year-old children belonging to different socio-economic classes were determined in two Chilean twin cities that are served by optimally fluoridated community water from the same waterworks facility. Low socio-economic status (LSES) children had a higher mean dm ft and DMFT indices (P<0.001) than high socioeconomic status (HSES) children. Prevalence of enamel fluorosis in the permanent teeth of LSES children was 0.79, significantly higher (X2= 9.0; P<0.003) than the value 0.59 found in HSES children. The proportion of Dean's scores 2. 3, 4 and 5 in first molars, mandibular and maxillary incisors in LSES children was higher than in HSES children (P<0.001). Differences in prevalence and seventy of enamel fluorosis between both groups are tentatively attributed lo a different pattern of tap water and tea consumption at pre-school ages. Suggestions are advanced to minimize the undesirable prevalence and severity of enamel fluorosis.  相似文献   
945.
946.
Sepsis due to candida infection is a major cause of mortality and morbidity on our unit. Over a period of 3 years and 4 months, 29 cases of candida septicaemia, diagnosed by blood cultures, were encountered at the burn unit at Augusta Regional Medical Center.

Factors known to predispose to fungal sepsis were present in all cases. All patients had large burns (14–98 per cent total body surface (TBSA) with a mean of 48.3 per cent). All but one patient had at least one central venous line. Respiratory problems requiring ventilator support were present in 24 patients.

Sixteen patients had Candida albicans sepsis, two in association with another fungal sepsis. Candida parapsilosis was encountered in nine patients, one in combination with another species. Four patients had Candida tropicalis.

Amphotericin B was prescribed therapeutically in 25 patients, in seven together with fluconazole. Two patients received fluconazole only and two received no antifungal therapy.

There were eight deaths all attributed to sepsis and all of whom had multiple organ failure. Five of those who died had completed a course of amphotericin B therapy, two were receiving treatment at the time of death, and one patient died before culture data became available. Early and aggressive therapy is advised and amphotericin B appears to be the drug of choice.  相似文献   

947.
Three dimensional (3D) phase contrast angiograms contain velocity data, which is discarded after the reconstruction of the projections. In extension to earlier work on velocity quantification with ungated 2D phase data, this paper shows that a useful estimate of the average velocity and flow rate can be extracted from ungated 3D phase contrast angiograms. Simulations and experiments in a phantom and in vivo were performed. For pulsatile flow and strong spin saturation, an over-estimation of the flow rate at the net in-flow end of the imaging volume and underestimation at the net out-flow end was observed. Imaging at lower RF tip angles yielded flow rates close to the correct value within the entire imaging volume. In contrast to ungated 2D experiments, the flow rates determined by repeated 3D experiments showed no variation.  相似文献   
948.
949.
950.
A variety of substances have been used at laminectomy sites to prevent postoperative epidural scarring. Free grafts of autologous subcutaneous fat are commonly used both clinically and experimentally. The free fat grafts usually survive, but decrease in size by about 50%. Postoperatively, subcutaneous seroma has been observed with the use of fat grafts, as well as recurrent symptoms of neural compression by the graft that required additional operations. When compared to the use of free grafts after laminectomy in dogs, Vicryl mesh produced slightly more scarring, but consistently less than that observed in control animals. The Vicryl mesh was resorbed by a minimal chronic inflammatory response over about 45 days. Seven of 11 fat-grafted zones showed signs of necrosis, at times with a greater collection of inflammatory cells than that associated with the Vicryl mesh. Of the 4 fat-grafted zones that showed good survival, 2 had gross evidence of neural compression. No surgical zone treated with Vicryl mesh exhibited evidence of neural compression. In view of these results, the use of Vicryl mesh at laminectomy sites may be a safer method of limiting postoperative epidural scar formation.  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