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   1391篇
  免费   85篇
  国内免费   10篇
耳鼻咽喉   5篇
儿科学   67篇
妇产科学   37篇
基础医学   163篇
口腔科学   44篇
临床医学   114篇
内科学   300篇
皮肤病学   41篇
神经病学   58篇
特种医学   184篇
外国民族医学   1篇
外科学   109篇
综合类   50篇
预防医学   116篇
眼科学   7篇
药学   80篇
中国医学   1篇
肿瘤学   109篇
  2022年   6篇
  2019年   9篇
  2018年   13篇
  2017年   19篇
  2016年   23篇
  2015年   35篇
  2014年   25篇
  2013年   56篇
  2012年   48篇
  2011年   49篇
  2010年   54篇
  2009年   58篇
  2008年   57篇
  2007年   56篇
  2006年   46篇
  2005年   36篇
  2004年   55篇
  2003年   35篇
  2002年   31篇
  2001年   27篇
  2000年   26篇
  1999年   45篇
  1998年   58篇
  1997年   63篇
  1996年   59篇
  1995年   48篇
  1994年   44篇
  1993年   39篇
  1992年   21篇
  1991年   16篇
  1990年   36篇
  1989年   22篇
  1988年   37篇
  1987年   29篇
  1986年   32篇
  1985年   17篇
  1984年   7篇
  1983年   12篇
  1982年   21篇
  1981年   6篇
  1980年   10篇
  1979年   14篇
  1978年   8篇
  1977年   7篇
  1976年   6篇
  1975年   5篇
  1974年   8篇
  1973年   8篇
  1972年   5篇
  1971年   5篇
排序方式: 共有1486条查询结果,搜索用时 0 毫秒
1.
2.
3.
4.
5.
A temperature probe based on the magnetic resonance properties of an encapsulated liquid crystal has been investigated. Large changes in magnetic resonance signals occur as the liquid crystal undergoes a phase transition from an anisotropic (nematic) state to the isotropic liquid. The low latent heat of such phase transitions allows for rapid phase changes during a hyperthermia treatment. Transition temperatures can be tailored by adding suitable compounds such as analogues of the liquid crystal or various solvents. Encapsulation is required to maintain the integrity of the liquid crystal, particularly for applications in vivo. Results of preliminary studies designed to demonstrate the technical feasibility of the concept are presented.  相似文献   
6.
We report here the results of a 9- to 11-yr follow-up of 2 cohorts in which spirometry and the single-breath N2 test were used throughout the follow-up period to determine the usefulness of the single-breath N2 test in identifying the smoker who is experiencing a rapid decline in FEV1 and is therefore likely to be at risk of developing chronic airflow limitation. The analyses are based on 734 subjects tested from 3 to 5 times over the follow-up period; 82 smokers developed an abnormal FEV1 during the follow-up period. Of these, 71 (87%) had had an abnormal single-breath N2 test at some time prior to the FEV1 becoming abnormal. Of the single-breath N2 test variables, CC/TLC was the only one significantly associated with the rate of decline of FEV1 in both cohorts once adjustments were made for age, sex, height, and smoking. We conclude that the single-breath N2 test can be useful in identifying the smoker who is at risk of developing chronic airflow limitation. However, its usefulness is diminished by the high proportion of smokers who have mild functional abnormalities but do not progress to develop chronic airflow limitation. We also find that the single-breath N2 test does not appear to have a useful predictive value in nonsmokers.  相似文献   
7.
Cutaneous metastasis of vaginal carcinoma is extremely rare. So far, the total number of reported skin metastasis of vaginal carcinoma is only one. We present another case with an unusual manifestation of vagina carcinoma metastasis: skin metastasis presenting as a leg ulcer on the lower leg.  相似文献   
8.
Localization of a gene for otosclerosis to chromosome 15q25-q26   总被引:5,自引:0,他引:5  
Among white adults otosclerosis is the single most common cause of hearing impairment. Although the genetics of this disease are controversial, the majority of studies indicate autosomal dominant inheritance with reduced penetrance. We studied a large multi- generational family in which otosclerosis has been inherited in an autosomal dominant pattern. Five of16 affected persons have surgically confirmed otosclerosis; the remaining nine have a conductive hearing loss but have not undergone corrective surgery. To locate the disease- causing gene we completed genetic linkage analysis using short tandem repeat polymorphisms (STRPs) distributed over the entire genome. Multipoint linkage analysis showed that only one genomic region, on chromosome 15q, generated a lod score >2.0. Additional STRPs were typed in this area, resulting in a lod score of 3.4. STRPs FES (centromeric) and D15S657 (telomeric) flank the 14. 5 cM region that contains an otosclerosis gene.   相似文献   
9.
There is increasing evidence that immunological mechanisms play a role in the pathogenesis and pathophysiology of endometriosis. It was therefore of interest to study interleukin-8 (IL-8), a chemokine, in the peritoneal fluid and peripheral blood of women undergoing laparoscopic procedures. The presence and concentrations of IL-8 in relation to endometriosis, infertility and abdominal pain were evaluated. Samples of peritoneal fluid (n = 49) and peripheral blood (n = 50) were obtained from 50 consecutive patients undergoing laparoscopic surgery for various gynaecological indications (abdominal pain, infertility, sterilization). IL-8 was present in the peritoneal fluid of most women (87%). The concentration of IL-8 in the peritoneal fluid was higher in women with endometriosis compared to women without (P = 0.02). This difference was more pronounced in early (stage 1) endometriosis (P = 0.001). IL-8 concentrations in the peritoneal fluid were also higher in women with early endometriosis compared to women with later stages of the disease (P = 0.003). Peripheral blood concentrations did not correlate with peritoneal fluid concentrations of IL-8 and/or the presence of endometriosis. We conclude that IL-8 is an important factor that may contribute to the pathogenesis of endometriosis possibly by promoting neovascularization. This information can be a guide in the development of new therapeutic approaches for the treatment of endometriosis.   相似文献   
10.
Karyotyping and DNA flow cytometry of metastatic ovarian yolk sac tumor   总被引:1,自引:0,他引:1  
We karyotyped a metastasis composed of pure yolk sac tumor derived from a primary ovarian germ cell tumor with two components: a dermoid cyst [DNA index (DI) 1.0] and a pure yolk sac tumor (DI 1.88). The metastatic yolk sac tumor had a hypertriploid karyotype and a DI of 1.78 and lacked the germ cell tumor marker i(12p). The absence of this marker in a metastasis from a tumor with a dermoid cyst component might be indicative for a pathogenesis of the yolk sac tumor similar to that of a dermoid cyst and different from that of dysgerminoma.  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