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   2387108篇
  免费   175166篇
  国内免费   3397篇
耳鼻咽喉   32528篇
儿科学   76971篇
妇产科学   63830篇
基础医学   353720篇
口腔科学   64805篇
临床医学   216557篇
内科学   463797篇
皮肤病学   52273篇
神经病学   188356篇
特种医学   89069篇
外国民族医学   490篇
外科学   358362篇
综合类   48198篇
现状与发展   12篇
一般理论   874篇
预防医学   187226篇
眼科学   54878篇
药学   177924篇
  11篇
中国医学   4643篇
肿瘤学   131147篇
  2021年   19630篇
  2019年   20260篇
  2018年   27911篇
  2017年   20972篇
  2016年   23430篇
  2015年   26402篇
  2014年   37087篇
  2013年   55483篇
  2012年   76761篇
  2011年   81589篇
  2010年   48269篇
  2009年   45627篇
  2008年   76408篇
  2007年   81343篇
  2006年   82027篇
  2005年   79482篇
  2004年   76006篇
  2003年   73222篇
  2002年   70909篇
  2001年   109610篇
  2000年   112337篇
  1999年   94273篇
  1998年   27454篇
  1997年   24055篇
  1996年   24347篇
  1995年   23034篇
  1994年   21203篇
  1993年   19995篇
  1992年   72663篇
  1991年   70704篇
  1990年   68984篇
  1989年   66229篇
  1988年   60831篇
  1987年   59693篇
  1986年   55735篇
  1985年   53543篇
  1984年   39729篇
  1983年   33776篇
  1982年   20157篇
  1979年   36231篇
  1978年   25959篇
  1977年   21488篇
  1976年   20586篇
  1975年   22033篇
  1974年   26433篇
  1973年   25012篇
  1972年   23449篇
  1971年   22273篇
  1970年   20426篇
  1969年   19515篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
BACKGROUND: Repairing dorsal nasal defects is a frequent challenge for dermatologic surgeons, mainly due to the high frequency of basal cell carcinomas on this site. Obvious scars, mismatched skin and distortion of the nasal contour are the surgical hazards that must be avoided in these cases. AIM: Our aim was to perform surgery involving a simple flap in order to repair medium to large defects on the dorsal side of the nose. METHODS: The dorsal horizontal advancement flap was studied in 12 patients, in order to evaluate the benefits and limits of this surgical procedure. RESULTS: The resulting scars on most of our patients were well-camouflaged among their natural skin lines, and there was neither distortion of the alar contour nor the nostril. CONCLUSIONS: This flap is easy to perform and, in selected cases, provides an outstanding alternative to second-intention healing, full-thickness skin grafts, transposition, rotation and pedicle flaps.  相似文献   
52.
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   
53.
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   
54.
55.
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   
56.
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   
57.
58.
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   
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