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   2949篇
  免费   163篇
  国内免费   29篇
耳鼻咽喉   24篇
儿科学   68篇
妇产科学   67篇
基础医学   303篇
口腔科学   40篇
临床医学   272篇
内科学   679篇
皮肤病学   45篇
神经病学   205篇
特种医学   148篇
外科学   629篇
综合类   35篇
预防医学   206篇
眼科学   25篇
药学   174篇
中国医学   9篇
肿瘤学   212篇
  2023年   23篇
  2022年   49篇
  2021年   101篇
  2020年   46篇
  2019年   71篇
  2018年   77篇
  2017年   55篇
  2016年   36篇
  2015年   64篇
  2014年   89篇
  2013年   147篇
  2012年   203篇
  2011年   222篇
  2010年   102篇
  2009年   88篇
  2008年   176篇
  2007年   157篇
  2006年   155篇
  2005年   135篇
  2004年   101篇
  2003年   113篇
  2002年   107篇
  2001年   64篇
  2000年   70篇
  1999年   40篇
  1998年   27篇
  1997年   23篇
  1996年   18篇
  1995年   13篇
  1994年   25篇
  1993年   12篇
  1992年   63篇
  1991年   47篇
  1990年   42篇
  1989年   39篇
  1988年   23篇
  1987年   20篇
  1986年   34篇
  1985年   26篇
  1984年   22篇
  1983年   24篇
  1979年   15篇
  1978年   13篇
  1977年   14篇
  1975年   12篇
  1974年   19篇
  1973年   10篇
  1969年   10篇
  1968年   11篇
  1967年   13篇
排序方式: 共有3141条查询结果,搜索用时 15 毫秒
931.
932.
A series of sixty-five patients with adenocarcinoma of the rectum and rectosigmoid is reviewed. Thirty-two patients had surgery alone, fourteen patients underwent postoperative radiation therapy, and nineteen patients underwent preoperative radiation therapy. A moderate dose program of 4,000 to 4,500 r was used. The postoperative treatment group had a higher incidence of stage C lesions and a higher recurrence rate, but there were no statistically significant differences in survival. Postoperative radiation therapy in patients with stage C lesions did not prolong life and is of little benefit. The preoperative treatment group tolerated the radiation very well, and there were no major complications. Eight patients underwent anterior resections in irradiated fields. Two minor anastomotic leaks subsequently healed spontaneously. There were no pelvic recurrences in the preoperative treatment group, and the incidence of lymph node metastases was 26% as opposed to 41% in controls. We conclude that preoperative moderate dose radiation is not associated with increased risk of morbidity or mortality. It may be useful in reducing the incidence of lymph node metastases and pelvic recurrence. The effect on survival is not determined in this study.  相似文献   
933.
934.
935.
936.
937.
938.
G W Hubbard  H Wanebo  M Fukuda  R Pace 《Cancer》1981,47(9):2177-2184
Although suppressor cells appear to be involved in the normal regulatory mechanism of the lymphoid system, they are also considered to have a role in the immunosuppression of certain malignancies. Suppressor activity of lymphocytes can be reproducibly measured by use of the mixed lymphocyte culture-mitogen interaction (MLC-M) in which the stimulating cell either is in the basal state or has been induced by Concanavalin A. This yields a quantitative measure of resting suppressor cell activity as well as the maximum generation of suppressor activity as induced by Con A. This test was performed, using autologous and allogenic cell combinations in a group of 13 cancer patients and 18 normal controls. Normal lymphocytes activated by Con A in 48-hour lymphocyte cultures significantly decreased the mitogenic response of lymphocytes from healthy, male donors to phytohemagglutinin (PHA), Con A, and Pokeweed mitogen (PWM) in both autologous and homologous systems. In contrast, Con A activated lymphocytes from cancer patients demonstrated diminished suppressor activity compared with controls in autologous (P less than 0.01), and allogenic (P less than 0.005) systems. There was a correlation between the degree of immunosuppression and suppressor cell activation: i.e., the patients most depressed generally had the lowest suppressor cell activation. Untreated lymphocytes from cancer patients also exerted suppressive effects on normal lymphocyte responses, suggesting an increased resting level of suppressor cells. These data suggest that in addition to having depressed cellular immune responses, cancer patients frequently have reduced capability to generate suppressor cell activity, which implies a generalized defect in this aspect of immune regulation.  相似文献   
939.
One hundred and twenty-four patients with knee osteoarthritis were reviewed at three stages over a mean of 24 months (range: 9-32 months) at the time of referral by the general practitioner, by the orthopedic consultant, and before surgery. At each visit, patients were examined and the American Knee Society score and Oxford Knee Society score were obtained. The functional element of the American Knee Score deteriorated significantly from the time of referral until the time of first orthopedic consultation (P=.005) and from the time of referral to the time of surgery (P=.006). The pain element of the American Knee Society score improved from the time of referral till the time of orthopedic assessment (P=.011). The change in Oxford Knee Society score between the time the patient was put on the waiting list to the time of surgery was not statistically significant (P=.30). This article questions the emphasis on surgical waiting times instead of symptoms and physical function in determining timing of surgery.  相似文献   
940.
Eighteen groups of seventy Atlantic salmon (Salmo salar L.) fry (initial mean body weight 0.8 (sd 0.01) g) were fed on semi-purified diets containing graded levels of l-threonine (Thr) in 15 litres aquaria at a temperature of 14.5+/-1 degrees C. Doses of Thr represented 1, 31, 41, 51, 62, 72, 83 and 93 % of its ideal level for optimum protein deposition. Indispensable amino acids other than Thr were included in the same proportion (on a g/16 g N basis) as in the Atlantic salmon fry whole-body carcass. Following 36 d of feeding and a 36 h fast, fry were killed for whole-body protein and amino acid analysis. Weight gain (r2 0.98), protein accretion (r2 0.97), and Thr accretion (r2 0.97) were linear (P<0.01) functions of Thr intake. Slope of the Thr accretion regression line showed that the efficiency of Thr utilisation above maintenance was 76 %. At zero Thr intake, fry lost 5.4 mg Thr/kg body weight0.75 per d. The Thr maintenance requirement was 7.2 mg/kg body weight0.75 per d and the Thr requirement for growth was 66 mg for 1 g protein deposition. Increasing doses of Thr resulted in increased (P<0.05) concentrations of histidine and lysine, and decreased concentrations of isoleucine in whole-body protein. The maintenance need for Thr represented 13.4 % of the total need for Thr. The data suggest that efficiency of Thr utilisation above maintenance is constant at all levels of Thr intake between 1 and 93 % of the level required for optimum protein deposition.  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