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   2606篇
  免费   156篇
  国内免费   18篇
耳鼻咽喉   7篇
儿科学   106篇
妇产科学   36篇
基础医学   332篇
口腔科学   23篇
临床医学   256篇
内科学   567篇
皮肤病学   19篇
神经病学   243篇
特种医学   83篇
外科学   329篇
综合类   39篇
一般理论   4篇
预防医学   217篇
眼科学   71篇
药学   167篇
中国医学   27篇
肿瘤学   254篇
  2023年   23篇
  2022年   29篇
  2021年   77篇
  2020年   36篇
  2019年   56篇
  2018年   88篇
  2017年   50篇
  2016年   53篇
  2015年   87篇
  2014年   87篇
  2013年   146篇
  2012年   197篇
  2011年   179篇
  2010年   125篇
  2009年   86篇
  2008年   161篇
  2007年   172篇
  2006年   169篇
  2005年   134篇
  2004年   131篇
  2003年   95篇
  2002年   74篇
  2001年   62篇
  2000年   58篇
  1999年   50篇
  1998年   16篇
  1997年   17篇
  1996年   22篇
  1995年   12篇
  1994年   17篇
  1993年   15篇
  1992年   19篇
  1991年   38篇
  1990年   14篇
  1989年   27篇
  1988年   21篇
  1987年   16篇
  1986年   13篇
  1985年   17篇
  1984年   8篇
  1983年   6篇
  1982年   7篇
  1981年   10篇
  1980年   8篇
  1978年   10篇
  1977年   7篇
  1975年   4篇
  1974年   4篇
  1971年   4篇
  1967年   4篇
排序方式: 共有2780条查询结果,搜索用时 15 毫秒
1.
2.
The present study aimed to determine the alterations of antioxidant activities in erythrocytes from patients with nonsmall cell lung carcinoma (NSCLC). A comparative study of the systemic antioxidant activities in red blood cell lysate from subjects with NSCLC and healthy control subjects was conducted. The antioxidants catalase, superoxide dismutase (SOD) and glutathione peroxidase (GPx) were measured using chemical kinetic reactions under spectrophotometry. In total, 189 cases of mostly advanced-stage IIIB or stage IV NSCLC and 202 healthy controls were studied. In subjects with lung cancer, there was similar catalase activity, lower SOD activity (median (interquartile range) 13.4 (9.0-27.2) versus 48.7 (27.0-64.3) U x (ghaemoglobulin(Hb)(-1)), and higher GPx activity (175.2 (126.6-288.3) versus 49.2 (39.5-59.2) mU x (gHb)(-1)) compared with controls. The antioxidant activities in lung cancer subjects were not associated with age, sex, smoking status, or tumour cell types. However, more advanced disease (stage IV compared with stage IIIB) was associated with lower SOD activity. Using multivariable analysis, the presence of lung cancer independently predicted SOD and GPx activities. In conclusion, nonsmall cell lung carcinoma in Chinese subjects is associated with alterations in systemic antioxidant activities, which may play an important role in carcinogenesis.  相似文献   
3.
Background: The cardiotoxic mechanism of local anesthetics may include interruption of cardiac sympathetic reflexes. The authors undertook this investigation to determine if clinically relevant concentrations of bupivacaine and levobupivacaine interfere with exocytotic norepinephrine release from cardiac sympathetic nerve endings.

Methods: Rat atria were prepared for measurements of twitch contractile force and 3[H]-norepinephrine release. After nerve endings were loaded with 3[H]-norepinephrine, the tissue was electrically stimulated in 5-min episodes during 10 10-min sampling periods. After each period, a sample of bath fluid was analyzed for radioactivity and 3[H]-norepinephrine release was expressed as a fraction of tissue counts. Atria were exposed to buffer alone during sampling periods 1 and 2 (S1 and S2). Control atria received saline (100 [mu]l each, n = 6 atria) in S3-S10. Experimental groups (n = 6 per group) received either bupivacaine or levobupivacaine at concentrations (in [mu]M) of 5 (S3-S4), 10 (S5-S6), 30 (S7-S8), and 100 (S9-S10).

Results: Bupivacaine and levobupivacaine decreased stimulation-evoked fractional 3[H]-norepinephrine release with inhibitory concentration 50% values of 5.1 +/- 0.5 and 6.1 +/- 1.3 [mu]m. The inhibitory effect of both local anesthetics (~70%) approached that of tetrodotoxin. Local anesthetics abolished the twitch contractions of atria with inhibitory concentration 50% values of 12.6 +/- 5.0 [mu]m (bupivacaine) and 15.7 +/- 3.9 [mu]m (levobupivacaine). In separate experiments, tetrodotoxin inhibited twitch contractile force by only 30%.  相似文献   

4.
5.
Winnie Annis  RN  BSN  CNOR 《AORN journal》2003,77(5):1028
  相似文献   
6.
7.
8.
Tamoxifen (TAM) has previously been shown to inhibit growth of the Dunning R3327 rat prostate adenocarcinoma and to elevate serum prolactin levels. The purpose of this study was to determine the role of prolactin in modulating the effects of tamoxifen on growth of the R3327 prostatic adenocarcinoma. Intact and castrated Copenhagen-Fischer male rats bearing the Dunning R3327 rat prostatic tumor were divided into groups and injected sc five times per week for 16 weeks as follows: vehicle; TAM (0.5 mg/kg); haloperidol (HALO; 0.5 mg/kg); bromocriptine (CB-154; 5 mg/kg); TAM plus HALO; or TAM plus CB-154. In both intact and castrated rats, agents that either raised (HALO) or lowered (CB-154) serum prolactin had little effect on prostatic tumor growth when administered singly. In intact rats, average tumor diameter in vehicle-treated controls increased 421% 16 weeks after the start of the experiment, and treatment with TAM or TAM plus HALO reduced this tumor growth by approximately one-half. Interestingly, CB-154 administered in combination with TAM completely blocked TAM inhibition of tumor growth in intact rats. In contrast to these results in intact rats, average tumor diameter increased 129% in TAM- and 118% in TAM plus HALO-treated castrated rats and was significantly greater than the characteristic retardation of tumor growth (49% increase) that occurred in the vehicle-treated castrate controls. In addition, combined treatment of TAM plus CB-154 in castrate rats resulted in an even greater increase (188%) in average tumor diameter. The inhibitory effect of TAM on R3327 prostatic tumor growth in intact rats appears to be an indirect effect resulting from its ability to reduce serum testosterone levels. In contrast, the stimulatory effect of TAM in castrate rats appears to result directly from an estrogen-like action, which can directly enhance prostatic tumor growth in the presence of low levels of circulating androgens; this stimulatory effect of TAM is more pronounced when prolactin levels are suppressed by CB-154. Clearly, castration alone is more effective than TAM therapy alone or in combination with castration in the retardation of the growth of the androgen-dependent R3327 prostatic tumor in rats.  相似文献   
9.
Inadequate débridement, extensive scarring, and breakdown of the wound have been commonly encountered after surgical débridement has been employed as the initial treatment of infection with Mycobacterium marinum involving the deep structures of the hand. Because of our disappointment with the results of this form of treatment, from 1982 to 1986 we treated twenty-four patients who had such an infection with rifampicin and ethambutol after a diagnostic biopsy was done. Surgical treatment was deferred until it was determined that the infection had not been controlled by the chemotherapy. The clinical outcome for these patients could be divided into three patterns: eleven patients (Group I) had a good result with no complications, three patients (Group II) had delayed healing of the wound, and ten patients (Group III) did not have a good response to conservative treatment and required one or more surgical débridements. Complications were sometimes associated with use of the drugs, and loss of visual acuity was a concern in three patients. In twenty-one (87 per cent) of the patients, at follow-up the function of the treated hand was equal to that of the other hand. Persistent pain, a discharging sinus, and previous local injection of steroids were unfavorable prognostic factors. If these factors are present, surgical débridement is advised.  相似文献   
10.
A group of bronchiectatic subjects in the clinically stable state were studied for systemic evidence of inflammation. The following parameters were evaluated: body weight, serum albumin, serum globulin, serum alpha 1-antitrypsin (alpha 1 AT) and peripheral white cell count. For serum albumin and globulin, comparison was made between subjects with bronchiectasis and control subjects with no known pulmonary disease matched for sex and age, and for serum alpha 1 AT and peripheral white cell count, matched for smoking habit as well. The bronchiectatic subjects showed systemic effects of inflammation as indicated by lower body weight and serum albumin (P less than 0.01), higher serum globulin (P less than 0.001), serum alpha 1 AT (P less than 0.05) and total leucocyte count (P less than 0.05). Differential white cell count showed that the elevation was distributed in most cell types. Correlation matrix was done for the above systemic parameters and indices of airway inflammation including sputum volume, purulence, and polymorph count and FEV1. There was an inverse correlation between total peripheral WBC count and FEV1 in percentage of predicted (P less than 0.01), and a positive correlation between sputum purulence and sputum polymorph score (P less than 0.05). This suggests that host peripheral leucocyte response may be a factor in the determination of lung function.  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