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   481篇
  免费   14篇
  国内免费   22篇
耳鼻咽喉   7篇
儿科学   3篇
妇产科学   15篇
基础医学   33篇
口腔科学   32篇
临床医学   63篇
内科学   83篇
皮肤病学   3篇
神经病学   23篇
特种医学   29篇
外科学   41篇
综合类   10篇
预防医学   41篇
眼科学   2篇
药学   55篇
中国医学   2篇
肿瘤学   75篇
  2023年   2篇
  2022年   4篇
  2021年   10篇
  2020年   6篇
  2019年   11篇
  2018年   7篇
  2017年   6篇
  2016年   8篇
  2015年   12篇
  2014年   18篇
  2013年   26篇
  2012年   34篇
  2011年   29篇
  2010年   14篇
  2009年   13篇
  2008年   25篇
  2007年   40篇
  2006年   24篇
  2005年   24篇
  2004年   17篇
  2003年   31篇
  2002年   32篇
  2001年   29篇
  2000年   12篇
  1999年   10篇
  1998年   8篇
  1997年   3篇
  1996年   4篇
  1995年   2篇
  1994年   1篇
  1993年   1篇
  1992年   5篇
  1991年   1篇
  1989年   6篇
  1988年   6篇
  1987年   7篇
  1986年   5篇
  1985年   1篇
  1983年   4篇
  1980年   2篇
  1979年   2篇
  1978年   5篇
  1977年   1篇
  1976年   2篇
  1975年   4篇
  1968年   1篇
  1965年   1篇
  1954年   1篇
排序方式: 共有517条查询结果,搜索用时 15 毫秒
31.
BACKGROUND: Correlation between p53 autoantibodies (p53 Abs) titers and the efficacy of Taiwanese lung cancer patients undergoing chemotherapy has never been investigated. Our present study aimed at evaluating putative possibility of using p53 Abs levels as a model system to monitor effect of chemotherapy and prognosis prediction of lung cancer. METHODS: The prevalence of p53 Abs in lung cancer patients and temporal alteration of p53 Abs titers in lung cancer patients carrying p53 Abs were investigated by using ELISA and Western blot analysis. RESULTS: p53 Abs was detected in 17 of 277 (6.14%) lung cancer patients, the positivity of p53 Abs in patients with small cell lung carcinoma and non-small cell lung carcinoma was 4.88% and 6.36%, respectively. No significant association between p53 Abs and patients' clinical manifestations was found. Titer of p53 Abs was decreased in 6 of 17 p53 Abs-carrying patients after chemotherapy. However, the decreasing p53 Abs titers were not correlated with patients' survival or chemotherapeutic efficacy. CONCLUSIONS: The prevalence of p53 Abs in Taiwanese lung cancer is much lower than that in Caucasians. It is unlikely that p53 Abs titer could be a monitoring indicator for the chemotherapeutic efficacy or a prognosis indicator of lung cancer.  相似文献   
32.
Aims: To investigate time to pregnancy (TTP) in male lead workers in order to determine the dose-response relation between blood lead and decreased fecundity. Methods: A total of 163 currently employed married male lead battery workers were classified into five categories of exposure based on questionnaire information and annual individual blood lead measurement. Information pertaining to the TTP was collected using personal interviews with 133 men and their spouses, with 280 valid pregnancies. The fecundability ratios (FRs) were calculated with the Cox discrete proportional hazard regression technique to evaluate the effects of lead exposure. Results: After other factors associated with TTP were controlled for, there was a dose-response relation between blood lead level and TTP. The measured FRs were 0.90 (95% CI 0.61 to 1.34), 0.72 (0.46 to 1.11), 0.52 (0.35 to 0.77), and 0.40 (0.27 to 0.59) for concurrent blood lead levels of <20, 20–29, 30–39, and ⩾40 µg/dl, respectively. Paired self comparison was also performed for 41 couples that had pregnancies prior to lead exposure and pregnancies with male occupational lead exposure. The TTP was prolonged for 0.15 cycles by a 1 µg/dl increase in blood lead. Conclusions: These results corroborate the hypothesis that a raised blood lead level affects fecundity. A blood lead level of less than 40 µg/dl may still significantly prolong TTP.  相似文献   
33.
In the Taiwan Surveillance of Antimicrobial Resistance programme, isolates were collected from 21 hospitals over a 3-month period in 2000 (TSAR II) and rates of resistance in Gram-positive pathogens were determined. Resistance rates were high including oxacillin resistance in Staphylococcus aureus (60%) and coagulase-negative staphylococci (80%), high-level gentamicin resistance (HLGR) in Enterococcus faecalis (60%) and penicillin non-susceptibility in Streptococcus pneumoniae (69%). Oxacillin resistance had increased from 1998 (TSAR I) and may be spreading into outpatient settings. In contrast, less than 2% enterococci were vancomycin-resistant. No linezolid resistance was found in either staphylococci or enterococci.  相似文献   
34.
OBJECTIVE: The purpose of this study was to compare the usefulness of gallium-67 citrate (67Ga) and technetium-99m tetrofosmin (Tc-TF) scan to detect Hodgkin's disease (HD). METHODS: In this study, 24 patients with HD underwent 67Ga and Tc-TF scan before receiving any therapy. RESULTS: 67Ga scan could detect HD in all 24 (100%) patients. Tc-TF scan could detect HD in 22/24 (91.6%) patients, but it was false-negative in one case of infradiaphragmatic HD and in another case with chemotherapy resistance. There was no significant difference in detection sensitivity between 67Ga and Tc-TF scan. CONCLUSIONS: We conclude that Tc-TF scan can not replace conventional 67Ga scan to detect HD.  相似文献   
35.
The effectiveness of technetium-99m tetrofosmin (Tc-TF) single photon emission computed tomography (SPECT) of the head and neck for detecting recurrence of nasopharyngeal carcinomas (NPC) was evaluated and compared with computed tomography (CT). Both Tc-TF SPECT and CT of the head and neck were performed in 36 NPC patients 4 months after radiotherapy. All 36 then underwent histopathological examinations of nasopharyngeal biopsies. Based on the histopathological results, the sensitivity, specificity, and accuracy of visually interpreted Tc-TF SPECT images, to differentiation of recurrent NPC from benign lesions, were 64%, 96%, and 86%, respectively. The sensitivity, specificity, and accuracy of CT for detecting recurrent NPC were 73%, 88%, and 83%, respectively. The Tc-TF SPECT has a better specificity but a lower sensitivity to differentiate benign lesions and recurrent/residual NPC when compared with CT. Combined Tc-TF SPECT and CT sensitivity and specificity were 100% and 88%, respectively. There are much better either test alone. However, further studies, including a larger NPC patient population, are warranted to determine the exact role and clinical usefulness of Tc-TF SPECT to differentiate benign lesions and recurrent/residual NPC.  相似文献   
36.
37.
Two growth experiments were conducted to estimate the minimum dietary iron requirement for juvenile hybrid tilapia, Oreochromis niloticus x O. aureus. Purified diets containing 0, 10, 30, 50, 100, 150, 200 and 400 mg Fe/kg from ferric citrate (Experiment 1) and 0, 10, 30, 50, 100, 150 and 200 mg Fe/kg from ferrous sulfate (Experiment 2) were fed to tilapia (mean initial weight: 0.63 +/- 0.01 g, Experiment 1; 0.64 +/- 0.01 g, Experiment 2) for 8 wk. In Experiment 2, 150 mg Fe/kg from ferric citrate was also included for comparison. The rearing water contained 1.07 micro mol/L iron, and supplemental levels were confirmed by analysis. Each diet was fed to three replicate groups of fish. In Experiment 1, weight gain and feed efficiency (FE) were highest (P < 0.05) in fish fed the diet supplemented with 150 mg Fe/kg, followed by fish fed diets with 50, 100 and 200 mg Fe/kg and lowest in fish fed the unsupplemented control diet. Hepatic iron concentration was highest in fish fed diets supplemented with >150 mg Fe/kg, followed by fish fed the diet with 100 mg Fe/kg and lowest in fish fed diets with /=100 mg Fe/kg and mean corpuscular volume (MCV) and mean corpuscular hemoglobin (MCH) were higher in fish fed diets with >/=150 mg Fe/kg than in fish fed the diet without iron supplementation. In Experiment 2, weight gain was higher in fish fed the diet with 50 mg Fe/kg than in fish fed diets with 150, 200 and /=50 mg Fe/kg and the ferric citrate comparison diet than fish fed diets with /=50 mg Fe/kg than in fish fed the unsupplemented control diet. Analyses by polynomial regression of weight gain and by broken-line regression of hepatic iron and blood Hb concentrations indicated that the dietary iron requirement for tilapia is approximately 150-160 mg Fe/kg and 85 mg Fe/kg with ferric citrate and ferrous sulfate as the iron source, respectively; it also appears that ferric citrate was approximately 50% as effective as ferrous sulfate in meeting the iron requirement.  相似文献   
38.
Research on the relation between phytoestrogens and breast cancer risk has been limited in scope. Most epidemiologic studies have involved Asian women and have examined the effects of traditional soy foods (e.g., tofu), soy protein, or urinary excretion of phytoestrogens. The present study extends this research by examining the effects of a spectrum of phytoestrogenic compounds on breast cancer risk in non-Asian US women. African-American, Latina, and White women aged 35-79 years, who were diagnosed with breast cancer between 1995 and 1998, were compared with women selected from the general population via random digit dialing. Interviews were conducted with 1,326 cases and 1,657 controls. Usual intake of specific phytoestrogenic compounds was assessed via a food frequency questionnaire and a newly developed nutrient database. Phytoestrogen intake was not associated with breast cancer risk (odds ratio = 1.0, 95% confidence interval: 0.80, 1.3 for the highest vs. lowest quartile). Results were similar for pre- and postmenopausal women, for women in each ethnic group, and for all seven phytoestrogenic compounds studied. Phytoestrogens appear to have little effect on breast cancer risk at the levels commonly consumed by non-Asian US women: an average intake equivalent to less than one serving of tofu per week.  相似文献   
39.
Shiau AL  Chu CY  Su WC  Wu CL 《Vaccine》2001,19(23-24):3277-3284
Attenuated intracellular bacteria, such as Salmonella and Shigella, have been exploited to act as gene delivery vectors. In this study, we report that nonpathogenic, live Escherichia coli can be used for the delivery of DNA vaccines in vivo, leading to generation of immune responses against plasmid-encoded foreign antigens. The pseudorabies virus (PrV) DNA vaccine carrying the glycoprotein D (gD) gene delivered by E. coli was able to induce protective immune responses in mice against a lethal PrV challenge. Co-delivery of E. coli carrying plasmid DNA encoding prothymosin alpha enhanced cellular immune responses to the PrV DNA vaccine delivered by E. coli. Our results suggest that nonpathogenic E. coli may be used as a vector for DNA vaccines in veterinary uses.  相似文献   
40.
Research on the relationship between iodine exposure and thyroid cancer risk is limited, and the findings are inconclusive. In most studies, fish/shellfish consumption has been used as a proxy measure of iodine exposure. The present study extends this research by quantifying dietary iodine exposure as well as incorporating a biomarker of long-term (1 year) exposure, i.e., from toenail clippings. This study is conducted in a multiethnic population with a wide variation in thyroid cancer incidence rates and substantial diversity in exposure. Women, ages 20-74, residing in the San Francisco Bay Area and diagnosed with thyroid cancer between 1995 and 1998 (1992-1998 for Asian women) were compared with women selected from the general population via random digit dialing. Interviews were conducted in six languages with 608 cases and 558 controls. The established risk factors for thyroid cancer were found to increase risk in this population: radiation to the head/neck [odds ratio (OR), 2.3; 95% confidence interval (CI), 0.97-5.5]; history of goiter/nodules (OR, 3.7; 95% CI, 2.5-5.6); and a family history of proliferative thyroid disease (OR, 2.5; 95% CI, 1.6-3.8). Contrary to our hypothesis, increased dietary iodine, most likely related to the use of multivitamin pills, was associated with a reduced risk of papillary thyroid cancer. This risk reduction was observed in "low-risk" women (i.e., women without any of the three established risk factors noted above; OR, 0.53; 95% CI, 0.33-0.85) but not in "high-risk" women, among whom a slight elevation in risk was seen (OR, 1.4; 95% CI, 0.56-3.4). However, no association with risk was observed in either group when the biomarker of exposure was evaluated. In addition, no ethnic differences in risk were observed. The authors conclude that iodine exposure appears to have, at most, a weak effect on the risk of papillary thyroid cancer.  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