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   56696篇
  免费   3676篇
  国内免费   110篇
耳鼻咽喉   537篇
儿科学   2358篇
妇产科学   1551篇
基础医学   7139篇
口腔科学   562篇
临床医学   8681篇
内科学   9712篇
皮肤病学   772篇
神经病学   5441篇
特种医学   1014篇
外国民族医学   2篇
外科学   4803篇
综合类   600篇
一般理论   109篇
预防医学   7854篇
眼科学   796篇
药学   3687篇
中国医学   61篇
肿瘤学   4803篇
  2023年   291篇
  2022年   431篇
  2021年   1026篇
  2020年   701篇
  2019年   1063篇
  2018年   1212篇
  2017年   988篇
  2016年   1077篇
  2015年   1259篇
  2014年   1729篇
  2013年   2766篇
  2012年   3988篇
  2011年   4293篇
  2010年   2374篇
  2009年   2151篇
  2008年   3880篇
  2007年   4125篇
  2006年   3978篇
  2005年   4130篇
  2004年   3906篇
  2003年   3680篇
  2002年   3399篇
  2001年   514篇
  2000年   381篇
  1999年   509篇
  1998年   699篇
  1997年   616篇
  1996年   495篇
  1995年   493篇
  1994年   440篇
  1993年   357篇
  1992年   284篇
  1991年   247篇
  1990年   221篇
  1989年   225篇
  1988年   203篇
  1987年   201篇
  1986年   179篇
  1985年   184篇
  1984年   213篇
  1983年   184篇
  1982年   223篇
  1981年   217篇
  1980年   163篇
  1979年   113篇
  1978年   116篇
  1977年   60篇
  1976年   65篇
  1975年   52篇
  1974年   75篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
This study determined the accuracy of fit of three-unit fixed partial dentures joined by an infrared soldering technique compared with one-piece fixed partial denture castings and individually cast crowns. Wax patterns of prepared Ivorine teeth, maxillary left central incisor and maxillary left canine, were injection molded; a plastic rod was used as a pontic. One group of patterns was cast as one-piece dentures; the other group was sectioned in the connector area, cast individually and then joined by infrared soldering. Castings were seated on their respective dies, embedded in epoxy resin, and sectioned. Gap distances between the casting and the die were measured at specified marginal sites with a profile projector. Results showed that the fit of infrared-soldered fixed partial dentures was significantly better than that of one-piece castings and was comparable with the fit of single crowns. The gap openings measured in all castings were within the range of clinical acceptability.  相似文献   
102.
103.
Frequency of symptoms of depression and selected health-related practices and events were measured in a sample of 219 high school students. Students reported numerous symptoms of depression. Relative proportions of boys and girls reporting symptoms of depression were not significantly different. However, girls reported experiencing more severe depression than their male counterparts. Depression correlated significantly with several of the 22 health practices and states of affect examined. Both the determinants and manifestations of depression in adolescent cohorts require in-depth investigation. Possible implications for school health personnel are discussed.  相似文献   
104.
Platelet-derived growth factor (PDGF) and insulin-like growth factor I (IGF-I) in combination have previously been shown to enhance periodontal regeneration. The objective of this study was to further characterize the biological effects of this combination of growth factors in non-human primates and compare the effects to those of each growth factor individually. Ligature-induced periodontitis was initiated in 10 cynomolgus monkeys. After periodontal lesions were established, surgery was performed, and either a methylcellulose gel vehicle or vehicle containing 10 μg each of either PDGF-BB, IGF-I or both PDGF-BB and IGF-I was applied to exposed root surfaces. Biopsies were taken 4 and 12 wk after treatment and the extent of periodontal regeneration was assessed by histomorphometry. At both 4 and 12 wk vehicle-treated lesions generally revealed minimal osseous defect fill (ODF) (8.5±2.1% and 14.5±5.7%, respectively) and new attachment (NA) (34.1±5.2% and 26.6±10.5%, respectively). IGF-I treatment did not significantly alter healing compared to vehicle in any parameter at both 4 and 12 wk. PDGFBB-treated sites exhibited significant (p<0.05) regeneration of NA (69.6±12.0%) at 12 wk; trends for PDGF-BB treatment effect were also observed in other parameters at 4 and 12 wk. although these increases were not statistically significant. Treatment with PDGF-BB/IGF-I resulted in 21.6±5.1 % and 42.5±8.3% ODF at 4 and 12 wk, respectively, and 64.1±7.7% and 74.6±7.4% NA at 4 and 12 wk, respectively (all significantly greater than vehicle, p<0.05). The results from this study demonstrated that: 1) IGF-1 alone at the dose tested did not significantly alter periodontal wound healing; 2) PDGF-BB alone significantly stimulated NA, with trends of effect on other parameters; and 3) the PDGF-BB/IGF-I combination resulted in significant increases in NA and ODF above vehicle at both 4 and 12 wk.  相似文献   
105.
BACKGROUND: Mixed venous saturation (S & OV0456;o2) is an important measurement that helps guide the care of critically ill patients. Invasive S & OV0456;o2 assessment in infants and children is often avoided because of the inherent risks. A noninvasive tissue saturation (S to 2) monitor has recently been developed that uses near-infrared spectroscopy to measure oxyhemoglobin saturation in muscle. In adult and animal studies, S to 2 correlated with oxygen delivery and S & OV0456;o2. There has been no evaluation in pediatric patients. OBJECTIVE: To evaluate tissue saturation as a noninvasive measure of mixed venous saturation in children. DESIGN: A prospective observational study. SETTING: Catheterization laboratory in a tertiary care children's medical center. PATIENTS: We studied 98 children (49 without intracardiac mixing and 49 with intracardiac mixing) 相似文献   
106.
107.
108.
PURPOSE: We systematically assessed the efficacy and safety of appetite stimulants in the management of cancer-related anorexia. Literature databases were searched for randomized controlled trials of appetite stimulants in the treatment of cancer anorexia. MATERIALS AND METHODS: Studies were graded according to quality. Fifty-five studies met inclusion criteria. RESULTS: Only two drugs have evidence to support their use for anorexia (progestins and corticosteroids). There is strong evidence against the use of hydrazine sulfate. The outcomes of these trials have been mixed and patient population heterogeneous. CONCLUSION: The optimal dose, time to start, and duration of treatment for many appetite stimulants for cancer anorexia is still unknown. A more systematic approach to research methodology with universal outcome measure and prospective randomized studies are need. Combination regimens are needed but this cannot at the present time be supported by the data presented.  相似文献   
109.
Summary DNA flow cytometry was used to examine the effects of five chemotherapeutic agents, vinblastine, cisplatinum, 5-fluorouracil, cyclophosphamide and Adriamycin, on mouse testes. Alterations in the haploid (1C), diploid (2C) and tetraploid (4C) cell compartments were assessed at 11, 29 and 56 days after giving mice a single intraperitoneal injection of each agent. Analysis of the histograms proved to be a rapid and reproducible method of monitoring injury in this animal model. Because this procedure can detect subtle testicular injuries, it is predicted that DNA histograms obtained from fine needle aspirates will gain increasing acceptance in the management of the oligo- and azoospermic patient.  相似文献   
110.
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