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   2635篇
  免费   189篇
  国内免费   22篇
耳鼻咽喉   20篇
儿科学   39篇
妇产科学   39篇
基础医学   383篇
口腔科学   30篇
临床医学   301篇
内科学   729篇
皮肤病学   57篇
神经病学   298篇
特种医学   29篇
外科学   194篇
综合类   7篇
一般理论   1篇
预防医学   271篇
眼科学   45篇
药学   214篇
中国医学   9篇
肿瘤学   180篇
  2024年   5篇
  2023年   32篇
  2022年   110篇
  2021年   119篇
  2020年   78篇
  2019年   93篇
  2018年   98篇
  2017年   78篇
  2016年   70篇
  2015年   83篇
  2014年   129篇
  2013年   131篇
  2012年   197篇
  2011年   220篇
  2010年   90篇
  2009年   113篇
  2008年   130篇
  2007年   160篇
  2006年   134篇
  2005年   130篇
  2004年   123篇
  2003年   140篇
  2002年   128篇
  2001年   22篇
  2000年   24篇
  1999年   15篇
  1998年   26篇
  1997年   16篇
  1996年   9篇
  1995年   19篇
  1994年   8篇
  1993年   8篇
  1992年   10篇
  1991年   13篇
  1990年   9篇
  1989年   8篇
  1988年   2篇
  1987年   12篇
  1986年   5篇
  1985年   5篇
  1984年   3篇
  1983年   2篇
  1982年   9篇
  1981年   4篇
  1980年   6篇
  1979年   5篇
  1977年   2篇
  1974年   6篇
  1966年   3篇
  1949年   1篇
排序方式: 共有2846条查询结果,搜索用时 0 毫秒
141.
AIM: To determine whether IFN-α is the agent that turns a slightly effective treatment (radiochemotherapy) into a potent therapy, we tested IFN-α for its synergistic properties. METHODS: Eight pancreatic carcinoma cell lines were treated with the single agents and combinations of these. The role of IFN-α regarding a) direct inhibitory effects; b) radio and chemosensitizing effects; c) anti-angiogenic properties and d) enhancement of immunogenicity was investigated. RESULTS: Our results show that IFN-α has direct inhibitory properties and some synergistic influence as determined by AnnexinV/PI stain and cell count. IFN-α is also able to prevent the increase in proliferation rate and VEGF secretion of CDDP resistant cells. Having taken the results from immunogenicity experiments together, we found cells that can be influenced by IFN-α but were less susceptible against T cells. Furthermore, high expression of MHC molecules, CD118, EGF-R and Fas was predictive for a good response. CONCLUSION: In conclusion, IFN-α has direct cytotoxic effects, acts as a radiosensitizer and circumvents tumor cell-regrowth after CDDP treatment. These mechanisms may be responsible for the good clinical outcome of CapRI.  相似文献   
142.
OBJECTIVE: To evaluate the relationship between self-reported correct and consistent condom use and chlamydial and gonococcal infection. DESIGN: Cross-sectional study. SETTING: An urban adolescent health care clinic.Patients A total of 509 adolescent girls tested for Chlamydia trachomatis and Neisseria gonorrhoeae infection by urine nucleic acid amplification tests.Main Outcome Measure Effect of condom use on infection rates of chlamydia and gonorrhea. Consistent condom use was defined as using condoms for every act of vaginal sex and correct use as consistent use without any of the following: beginning sex without a condom, taking it off before finishing sex, flipping it over, condom breakage, or condom slippage. RESULTS: A total of 95% of the participants were African American, with a mean age of 16.6 years. Chlamydia prevalence was 21% (105/509) and gonorrhea prevalence was 7% (36/509). Condom errors were reported by 316 (71%) of 442 participants who had reported using a condom at least once in the previous 3 months. Consistent use was reported by 176 patients (35%); however, both correct and consistent use was reported by only 80 patients (16%). After adjusting for confounders, correct and consistent use was protective for chlamydia (odds ratio, 0.4; 95% confidence interval, 0.2-1.0) and highly protective for gonorrhea (odds ratio, 0.1; 95% confidence interval, 0-0.7). CONCLUSION: Our findings indicate that assessing both correctness and consistency of use is important for evaluation of condom effectiveness.  相似文献   
143.
A method for synergistic integration of multimodal sensor data is proposed in this paper. This method is based on two aspects of the integration process: (1) achieving synergistic integration of two or more sensory modalities, and (2) fusing the various information streams at particular moments during processing. Inspired by psychophysical experiments, we propose a self-supervised learning method for achieving synergy with combined representations. Evidence from temporal registration and binding experiments indicates that different cues are processed individually at specific time intervals. Therefore, an event-based temporal co-occurrence principle is proposed for the integration process. This integration method was applied to a mobile robot exploring unfamiliar environments. Simulations showed that integration enhanced route recognition with many perceptual similarities; moreover, they indicate that a perceptual hierarchy of knowledge about instant movement contributes significantly to short-term navigation, but that visual perceptions have bigger impact over longer intervals.  相似文献   
144.
145.
146.
147.
Severe Protein-Calorie Malnutrition after Bariatric Procedures   总被引:1,自引:0,他引:1  
Background: Serious nutritional complications after Roux-en-Y gastric bypass (RYGBP) are infrequent. In a retrospective study of patients operated during a 68-month period, malnutrition was investigated to analyze circumstances associated with nutritional failure. Methods: In 236 consecutive RYGBPs, 11 patients with severe malnutrition were identified (4.7%) with age 45.1 ± 10.6 years (10 females/1 male) and initial BMI 54.6 ± 8.4 kg/m2. Results: In these 11 patients, the derangement was diagnosed 17.9 ± 15.8 months after RYGBP, following defined events in 63.6% (gastric stenosis, associated diseases ) or mostly exaggeration of expected symptoms in 36.4% (vomiting without endoscopic abnormalities). BMI then was 31.4 ± 8.6 kg/m2 (42.5 ± 9.9% total reduction, or 2.4 ± 2.1% decrease/month), and serum albumin and hemoglobin were 24.0 ± 8.2 g/L and 97.0 ± 23.0 g/L respectively. Edema was present in 45.4% (5/11), hospitalization was required in 54.5% (6/11), and 18.2% (2/11) eventually died. Conclusions: Serious malnutrition was unusual but not exceedingly rare in this series. Exogenous precipitating factors were clearly identified in 63.6% of the patients. Careful clinical and nutritional follow-up is recommended to prevent these uncommon but potentially dangerous complications.  相似文献   
148.
149.
This study aimed at identifying and performing content validation of the defining characteristics of the diagnoses of fear and anxiety for a burned patient. An instrument made up of manifestations of both diagnoses presented by Taxionomy I of the North American Nursing Diagnoses Association was elaborated, as well as others that were found in the literature. Sixteen nurses were interviewed. Out of the 97 characteristics presented in the instrument, 31 were excluded for the diagnoses "fear", and 27 for "anxiety". Eight characteristics had a score average above 0.70 for "fear" and 18 for "anxiety". The characteristics with the highest score were "expressed concern due to changes in life events" for anxiety and "insomnia referred or perceived" for fear.  相似文献   
150.
In this study, the authors examined the effects of alcohol, tobacco, and drug use on plasma testosterone and seminal parameters (in accordance with the World Health Organization's standards) in healthy Argentine medical students (n = 34). Some alterations in seminal parameters were detected in 19 (56%) subjects. Alcohol and tobacco use were correlated significantly, p = 0.005; subjects who used these substances exhibited a nonsignificant reduction in sperm concentration, motility, viability, and normal morphology. There was a significant decrease in sperm motility among students who used moderate amounts of aspirin (i.e., > or = 500 mg/wk). The authors concluded that alcohol, tobacco, and aspirin use could have had detrimental effects on seminal parameters and that men who wish to procreate should be warned of such effects. Doses, exposure time, and interactions with other variables deserve additional study.  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