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   1584466篇
  免费   126167篇
  国内免费   3899篇
耳鼻咽喉   20273篇
儿科学   51126篇
妇产科学   44376篇
基础医学   223037篇
口腔科学   41564篇
临床医学   142923篇
内科学   320915篇
皮肤病学   35648篇
神经病学   133598篇
特种医学   59462篇
外国民族医学   477篇
外科学   237312篇
综合类   35734篇
现状与发展   5篇
一般理论   750篇
预防医学   126532篇
眼科学   35197篇
药学   110718篇
  2篇
中国医学   3646篇
肿瘤学   91237篇
  2021年   13591篇
  2019年   14384篇
  2018年   19831篇
  2017年   15299篇
  2016年   17026篇
  2015年   19343篇
  2014年   27426篇
  2013年   40782篇
  2012年   56068篇
  2011年   59540篇
  2010年   34854篇
  2009年   33132篇
  2008年   55421篇
  2007年   58760篇
  2006年   58895篇
  2005年   57820篇
  2004年   55251篇
  2003年   52469篇
  2002年   50460篇
  2001年   74550篇
  2000年   75731篇
  1999年   63275篇
  1998年   19299篇
  1997年   17389篇
  1996年   17396篇
  1995年   16380篇
  1994年   14853篇
  1993年   13942篇
  1992年   46838篇
  1991年   44445篇
  1990年   42373篇
  1989年   40352篇
  1988年   37033篇
  1987年   36213篇
  1986年   33701篇
  1985年   32206篇
  1984年   25063篇
  1983年   21288篇
  1982年   13762篇
  1981年   12180篇
  1979年   21398篇
  1978年   15376篇
  1977年   12864篇
  1976年   12070篇
  1975年   12208篇
  1974年   14552篇
  1973年   14059篇
  1972年   13006篇
  1971年   11786篇
  1970年   11201篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
992.
993.
Cytokines play a pivotal role in the pathogenesis of degenerative joint disease but also in inflammatory conditions as well as osteoarthritis (OA) and rheumatoid arthritis (RA). A key role is attributed to interleukin-1 and tumor necrosis factor-α. Certain cytokines that can inhibit the activity of catabolic cytokines have great therapeutic potential and are currently being investigated in numerous clinical studies. Available scientific findings indicate that proinflammatory cytokines stimulate cartilage breakdown and blockade of these cytokines can protect the cartilage.  相似文献   
994.
995.
Lesley C Dinwiddie 《Nephrology nursing journal》2004,31(6):653-60, 671; quiz 661-2
Vascular access is the leading cause of morbidity in the hemodialysis patient population. Arteriovenous fistulas (AVFs) have the lowest complication rate while catheters have the highest. Though significant effort is being made to increase the number of AVFs and lower the number of catheters, annual data show that the number of catheters is increasing. To improve vascular access-related patient outcomes, catheter dysfunction needs to be managed by a vascular access team using the CQI process that begins with a comprehensive algorithm for treatment.  相似文献   
996.
997.
The purpose of this qualitative study was to examine the process of transformation of personal beliefs, values, feelings, and knowledge (meaning perspectives) underlying occupational change in a small group of clients with rheumatoid arthritis during home-based rehabilitation. A grounded theory approach used to collect and analyze data concurrently included: (1) a sample of five adult clients diagnosed with rheumatoid arthritis in occupational therapy, (2) data collection through 28 semi-directed interviews, and (3) data analysis using the constant comparison method. The study identified meaning perspectives of these clients with rheumatoid arthritis and explored the transformation of perspectives related to the modification of occupational performance. The study suggests that the exploration of meaning perspective transformation by clients and therapists could be a potential part of rehabilitation intervention.  相似文献   
998.
OBJECTIVE: The more atherogenic lipid profile seen in peritoneal dialysis (PD) patients cannot fully explain the increased incidence of atherosclerosis in this population. Oxidative modification of low-density lipoproteins (LDL) is considered to play a central role in the atherogenic process, whereas high-density lipoprotein (HDL) protects LDL from oxidation. On the other hand, it has been suggested that the LDL and HDL of PD patients are more resistant to oxidation than those of control subjects, while PD-HDL equally protects LDL from oxidation compared to control-HDL. Two HDL-associated enzymes have been shown to protect both LDL and HDL from oxidation: paraoxonase (PON1) and HDL-associated platelet-activating factor acetylhydrolase (HDL-PAF-AH). Furthermore, low PON1 activity and high total plasma PAF-AH concentration, which represents mainly the LDL-associated enzyme, have been shown to be independent risk factors for coronary artery events in the general population. However, there are limited data regarding possible alterations of these enzymes in PD patients. The aim of our study was to examine the possible alterations of PON1 and PAF-AH activities in patients undergoing PD. DESIGN: A cross-sectional study. SETTING: A university medical center. PARTICIPANTS: 56 PD patients of Caucasian origin and 86 matched controls were studied. MEASUREMENTS: In all subjects, serum PON1 activity toward paraoxon (paraoxonase) and phenylacetate (arylesterase), as well as total serum and HDL-PAF-AH activities were measured; PON1 genetic polymorphisms known to influence PON1 activity (Q192R and M55L) were determined. RESULTS: The PD patients exhibited significantly increased serum PON1 (paraoxonase) and PON1 (arylesterase) activities compared to controls, regardless of the PON1 polymorphisms or the levels of HDL cholesterol. Additionally, PD patients had significantly elevated activities of total serum PAF-AH and HDL-PAF-AH, independently of the levels of LDL or HDL cholesterol. The ratio of HDL-PAF-AH/ total PAF-AH, which has recently been suggested to be a potential marker of atherogenicity, was decreased in these patients compared to controls. Moreover, no difference in the prevalence of PON1 polymorphisms between PD patients and controls was found. CONCLUSION: The elevated activities of PON1 and HDL-PAF-AH could explain the increased resistance of PD-HDL to oxidation; the higher activity of total PAF-AH and the decreased HDL-PAF-AH/ total PAF-AH ratio could contribute to the increased incidence of atherosclerosis in these patients.  相似文献   
999.
BACKGROUND: Solid organ transplant recipients may develop numerous or life-threatening skin cancers. In addition to aggressive standard treatment of skin cancer, reduction of immunosuppression has been considered an adjuvant therapeutic strategy, albeit without direct proof of efficacy. OBJECTIVE: To review the rationale for and evidence supporting the efficacy of reduction of immunosuppression for severe skin cancer in transplant recipients. METHODS: Review of the literature regarding direct and indirect evidence on reduction of immunosuppression for transplant-associated skin cancer. RESULTS: Although there are no randomized controlled trials of reduction of immunosuppression as a therapeutic intervention for transplant patients with skin cancer, multiple lines of evidence suggest that this strategy may be an effective adjuvant therapy. A randomized trial has demonstrated a lower incidence of skin cancer in transplant recipients after reduction of immunosuppression, albeit in a cohort not previously affected by skin cancer. Case series of reduction or cessation of immunosuppression demonstrate a lower incidence of skin cancer or improved outcomes of preexisting skin cancer. Lower overall immunosuppression is associated with a lower incidence of skin cancer. Multiple cancers affecting the skin have been shown to regress with reduction of immunosuppression. CONCLUSIONS: Reduction of immunosuppression may be an effective adjuvant therapeutic strategy when confronting severe transplant-associated skin cancer. The risks of reduction of immunosuppression must be better defined, and randomized trials of this strategy are necessary.  相似文献   
1000.
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