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   2360180篇
  免费   171828篇
  国内免费   3335篇
耳鼻咽喉   32270篇
儿科学   76098篇
妇产科学   62848篇
基础医学   349378篇
口腔科学   63940篇
临床医学   212899篇
内科学   458605篇
皮肤病学   51958篇
神经病学   185459篇
特种医学   88472篇
外国民族医学   489篇
外科学   356107篇
综合类   47516篇
现状与发展   12篇
一般理论   848篇
预防医学   183926篇
眼科学   54663篇
药学   175616篇
  11篇
中国医学   4582篇
肿瘤学   129646篇
  2021年   18989篇
  2019年   19541篇
  2018年   27066篇
  2017年   20360篇
  2016年   22748篇
  2015年   25644篇
  2014年   36099篇
  2013年   53958篇
  2012年   74767篇
  2011年   79576篇
  2010年   47143篇
  2009年   44569篇
  2008年   74737篇
  2007年   79665篇
  2006年   80481篇
  2005年   77957篇
  2004年   74565篇
  2003年   71919篇
  2002年   69554篇
  2001年   108944篇
  2000年   111618篇
  1999年   93637篇
  1998年   27016篇
  1997年   23662篇
  1996年   24055篇
  1995年   22716篇
  1994年   20895篇
  1993年   19715篇
  1992年   72258篇
  1991年   70503篇
  1990年   68889篇
  1989年   66152篇
  1988年   60787篇
  1987年   59616篇
  1986年   55689篇
  1985年   53409篇
  1984年   39611篇
  1983年   33636篇
  1982年   19920篇
  1979年   36126篇
  1978年   25869篇
  1977年   21366篇
  1976年   20503篇
  1975年   22091篇
  1974年   26446篇
  1973年   25070篇
  1972年   23444篇
  1971年   22290篇
  1970年   20477篇
  1969年   19542篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
PURPOSE: The aim of this study was to determine if the concomitant use of ketorolac 0.4% and cyclosporin-A improves patient comfort during the induction phase in treating chronic dry eye disease. METHODS: Patients (n = 52) with clinically diagnosed dry eye were randomized to receive either cyclosporin-A monotherapy twice-daily (BID) or a BID adjunctive regimen of ketorolac, followed by the instillation of cyclosporin-A 10 min later. Study visits were at baseline, week 2, and week 6. At each study visit, patients underwent an evaluation for corneal staining, Schirmer's scores, and tear break-up time tests. Patients were asked to rate ocular comfort on a 4-point scale and to complete the ocular surface disease index (OSDI). Changes from baseline readings were recorded at week-2 and week-6 visits, and final patient success on treatment regimen was evaluated at week 6. RESULTS: After 6 weeks, the mean ocular comfort score of adjunctive patients improved 2.55 +/- 0.95 points, versus 1.53 +/- 0.91 points for monotherapy (P = 0.309). The adjunctive regimen provided significantly greater corneal staining reductions versus monotherapy, mean reduction in staining of 1.74 +/- 0.9, versus 1.27 +/- 0.56 (P = 0.044). CONCLUSIONS: Concurrent ketorolac 0.4% use with cyclosporin-A significantly reduced corneal staining and increased comfort in the induction phase.  相似文献   
52.
Primary chemotherapy administered to breast cancer patientsis the best model to identify baseline features able to predictwhich patients may be most likely to benefit or not from a cytotoxicregimen. In the March issue of Annals of Oncology two papersevaluated the predictive role of immunohistochemical p53 expressionon  相似文献   
53.
54.
CONTEXT: Although the nonmedical use of stimulant drugs such as cocaine and methamphetamine is increasingly common in many rural areas of the United States, little is known about the health beliefs of people who use these drugs. PURPOSE: This research describes illicit stimulant drug users' views on health and health-related concepts that may affect their utilization of health care services. METHODS: A respondent-driven sampling plan was used to recruit 249 not-in-treatment, nonmedical stimulant drug users who were residing in 3 rural counties in west central Ohio. A structured questionnaire administered by trained interviewers was used to collect information on a range of topics, including current drug use, self-reported health status, perceived need for substance abuse treatment, and beliefs about health and health services. FINDINGS: Participants reported using a wide variety of drugs nonmedically, some by injection. Alcohol and marijuana were the most commonly used drugs in the 30 days prior to the interview. Powder cocaine was used by 72.3% of the sample, crack by 68.3%, and methamphetamine by 29.7%. Fair or poor health status was reported by 41.3% of the participants. Only 20.9% of the sample felt they needed drug abuse treatment. Less than one third of the sample reported that they would feel comfortable talking to a physician about their drug use, and 65.1% said they preferred taking care of their problems without getting professional help. CONCLUSIONS: Stimulant drug users in rural Ohio are involved with a range of substances and hold health beliefs that may impede health services utilization.  相似文献   
55.
OBJECTIVE: To assess the effect of glucose control on the rate of growth of fetuses in women with pregestational diabetes mellitus (Types 1 and 2). METHODS: All pregestational diabetic women booked at Mater Mothers' Hospital, Brisbane, Australia, between 1 January 1994 and 31 December 2002, were included. Pregnancies with congenital fetal anomalies, multiple pregnancies, and pregnancies terminated prior to 20 weeks' gestation were excluded. Dating scans were performed before 14 weeks' gestation and serial scans were performed at 18, 24, 28, 32 and 36 weeks. Fetal parameters, including biparietal diameter, femur length and abdominal circumference, were recorded. The daily growth rates for biparietal diameter, femur length, and fetal abdominal area were calculated and compared with those in a low-risk (non-diabetic) population. The growth rates in fetuses of women with satisfactory diabetic control (HbA1c < 6.5%) and unsatisfactory control (HbA1c > or = 6.5%) in the three trimesters were compared. RESULTS: A total of 174 diabetic pregnancies were included and a total of 997 ultrasound scans were performed. The growth rates for fetuses of mothers with diabetes mellitus were significantly higher than for those in the low-risk population. The z-scores for biparietal diameter, femur length, and fetal abdominal area were 0.18, 0.59 and 1.44, respectively. Fetuses of diabetic mothers with high HbA1c in the first trimester had significantly greater fetal abdominal area growth rate than those with normal HbA1c (fetal abdominal area z-score of 1.7 vs. 0.75, P = 0.009). Although the fetal abdominal area z-scores in fetuses of diabetic mothers with high HbA1c in the second or third trimesters were also higher than those with normal HbA1c levels, the differences did not reach statistical significance. Maternal obesity did not influence the fetal growth rate. CONCLUSION: The rate of growth of fetuses of diabetic mothers differs from that of the normal population. Growth acceleration persists until the late third trimester. Moreover, periconceptional glucose control appears to have a significant effect on accelerated growth of the fetal abdominal area.  相似文献   
56.
57.
Continual loading and articulation cycles undergone by metallic (e.g., titanium) alloy arthroplasty prostheses lead to liberation of a large number of metallic debris particulates, which have long been implicated as a primary cause of periprosthetic osteolysis and postarthroplasty aseptic implant loosening. Long-term stability of total joint replacement prostheses relies on proper integration between implant biomaterial and osseous tissue, and factors that interfere with this integration are likely to cause osteolysis. Because multipotent mesenchymal stem cells (MSCs) located adjacent to the implant have an osteoprogenitor function and are critical contributors to osseous tissue integrity, when their functions or activities are compromised, osteolysis will most likely occur. To date, it is not certain or sufficiently confirmed whether MSCs endocytose titanium particles, and if so, whether particulate endocytosis has any effect on cellular responses to wear debris. This study seeks to clarify the phenomenon of titanium endocytosis by human MSCs (hMSCs), and investigates the influence of endocytosis on their activities. hMSCs incubated with commercially pure titanium particles exhibited internalized particles, as observed by scanning electron microscopy and confocal laser scanning microscopy, with time-dependent reduction in the number of extracellular particles. Particulate endocytosis was associated with reduced rates of cellular proliferation and cell-substrate adhesion, suppressed osteogenic differentiation, and increased rate of apoptosis. These cellular effects of exposure to titanium particles were reduced when endocytosis was inhibited by treatment with cytochalasin D, and no significant effect was seen when hMSCs were treated only with conditioned medium obtained from particulate-treated cells. These findings strongly suggest that the biological responses of hMSCs to wear debris are triggered primarily by the direct endocytosis of titanium particulates, and not mediated by secreted soluble factors. In this manner, therapeutical approaches that suppress particle endocytosis could reduce the bioreactivity of hMSCs to particulates, and enhance long-term orthopedic implant prognosis by minimizing wear-debris periprosthethic osteolysis.  相似文献   
58.
59.
60.
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