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   248350篇
  免费   18586篇
  国内免费   1117篇
耳鼻咽喉   2798篇
儿科学   6478篇
妇产科学   4600篇
基础医学   32404篇
口腔科学   4556篇
临床医学   25186篇
内科学   52577篇
皮肤病学   3390篇
神经病学   23893篇
特种医学   8424篇
外国民族医学   11篇
外科学   38347篇
综合类   3480篇
一般理论   318篇
预防医学   21015篇
眼科学   6559篇
药学   16911篇
  4篇
中国医学   357篇
肿瘤学   16745篇
  2023年   1213篇
  2022年   935篇
  2021年   4888篇
  2020年   3268篇
  2019年   5317篇
  2018年   5984篇
  2017年   4484篇
  2016年   4974篇
  2015年   5857篇
  2014年   8635篇
  2013年   11843篇
  2012年   18088篇
  2011年   18975篇
  2010年   10616篇
  2009年   9462篇
  2008年   16652篇
  2007年   17526篇
  2006年   17384篇
  2005年   17337篇
  2004年   16280篇
  2003年   15113篇
  2002年   14078篇
  2001年   2147篇
  2000年   1610篇
  1999年   2176篇
  1998年   2582篇
  1997年   2097篇
  1996年   1783篇
  1995年   2055篇
  1994年   1725篇
  1993年   1538篇
  1992年   1257篇
  1991年   1168篇
  1990年   1011篇
  1989年   988篇
  1988年   970篇
  1987年   956篇
  1986年   953篇
  1985年   973篇
  1984年   1207篇
  1983年   1118篇
  1982年   1325篇
  1981年   1289篇
  1980年   1124篇
  1979年   704篇
  1978年   738篇
  1977年   630篇
  1976年   574篇
  1975年   463篇
  1974年   479篇
排序方式: 共有10000条查询结果,搜索用时 78 毫秒
991.
This study histologically evaluated recombinant human platelet-derived growth factor-BB (rhPDGF-BB) in combination with beta-tricalcium phosphate (beta-TCP) for the treatment of human intraosseous periodontal defects. Eight patients, each with two teeth treatment planned for extraction, were enrolled. Presurgical measurements included probing depth, clinical attachment level, and recession. Initial surgery consisted of flap reflection, debridement, placement of a root notch through the base of calculus, scaling and root planing, root biomodification with 50 mg/mL tetracycline, grafting with rhPDGF-BB + beta-TCP, and complete wound closure. One tooth in each patient was treated with 0.3 mg/mL of rhPDGF-BB + beta-TCP, and the other tooth was treated with 1.0 mg/mL of rhPDGF-BB + beta-TCP. After a minimum of 6 months of healing, postsurgical clinical measurements were made, and teeth were removed en bloc. Soft tissue healing was uneventful. Histologic evaluation demonstrated new bone, cementum, and periodontal ligament coronal to the reference notch in 13 of the 16 teeth. Six of the eight 0.3-mg/mL sites and seven of the eight 1.0-mg/mL sites demonstrated periodontal regeneration. This study provides proof of principle that 0.3 mg/mL and 1.0 mg/mL of rhPDGF-BB and beta-TCP can promote periodontal regeneration in human intraosseous periodontal defects.  相似文献   
992.
OBJECTIVE: To compare the costs of providing dental treatment under general anaesthesia or sedation for special needs patients. METHODS: After a Delphi exercise, a questionnaire was designed, piloted and then sent to nine NHS Trust dental service managers, within the Salaried Dental Services in the North East of England, to obtain information on the costs incurred during the treatment of special needs patients using sedation or general anaesthesia. The questionnaire related to the average number of such patients treated per session, staff costs, depreciation cost for buildings and equipment, and overhead costs including consumables and drugs. RESULTS: All nine dental service managers returned completed questionnaires. The all-inclusive cost for treatment per patient under general anaesthesia ranged from 203.65-479.50 pounds (mean cost: 285.79 pounds) and for sedation from 57.60-153.50 pounds (mean cost: 90.81 pounds). On average three special needs patients were treated per session. The greatest variation in the costs for general anaesthesia was due to staffing costs, which ranged from 1064.10 to 350.00 pounds per session across the Trusts. CONCLUSIONS: In the small number of centres sampled, the cost of delivering dental care under sedation or general anaesthesia was shown to vary widely. Overall, the mean cost of sedation was one-third that of general anaesthesia. However, the cost of both was substantial and cognisance needs to be taken of the costs of such services.  相似文献   
993.
OBJECTIVES: Adhesive analysis, under the scanning electron microscope of microtensile specimens that failed through the adhesive interface, was conducted to evaluate the amount of voids present at the axial versus gingival cavity walls of class II composite restorations restored under in vivo and in vitro conditions. METHODS: Five patients received class II resin composite restorations, under in vivo and in vitro conditions. A total of 14 premolar teeth yielded 59 (n=59) microtensile adhesive specimens that fractured through the adhesive interface. The fractured surfaces of all specimens were examined and the % area of voids was measured. RESULTS: Voids at the adhesive joint were highly predictive of bond strengths. An increase in the number of voids resulted in a decrease in the microtensile bond strength. The area of voids at the adhesive interface was as follows: in vivo axial 13.6+/-25.6% (n=12); in vivo gingival 48.8+/-29.2% (n=12); in vitro axial 0.0+/-0.0% (n=19) and in vitro gingival 11.7+/-17.6% (n=16). SIGNIFICANCE: Composite resin may bond differently to dentin depending upon the amount of voids and the cavity wall involved. The bond to the gingival wall was not as reliable as the bond to the axial wall. An increase in the amount of surface voids was a major factor for reducing microtensile bond strengths of adhesive to dentin.  相似文献   
994.
995.
We report the case of a woman of 34 years who had ulcerative colitis and atypical pyoderma gangrenosum. The pyoderma gangrenosum responded to conservative treatment.  相似文献   
996.
997.
Ceramic materials provide an alternative when choosing a tooth-colored restoration. Currently, posterior composite restorations can be used to achieve esthetic restorations; however, they have many disadvantages with regard to wear, polymerization shrinkage, discoloration, marginal leakage, and technique sensitivity. The use of CEREC CAD/CAM enables the dentist to place feldspathic porcelain (Vitablocs Mark II) and machinable glass ceramic (Dicor MGC) restorations in a single visit. When compared to composite materials, these materials closely approximate the physical properties of enamel in compressive and tensile strength and wear resistance. This study evaluated 50 CEREC CAD/CAM restorations after 4 years in service. Restorations ranged from Class I to 7/8s crown preparations.  相似文献   
998.
999.
In 1997, the American Dental Association (ADA) and the American Academy of Orthopaedic Surgeons (AAOS) published an advisory statement regarding antibiotic prophylaxis for patients with total joint replacements undergoing dental treatment. The first periodic update of these guidelines was published in 2003. Nevertheless, confusion exists among dentists and physicians as to the clinical indications for premedication in this patient population. This article serves as an overview of current recommendations for use of chemoprophylaxis in the dental treatment of patients ith prosthetic joints.  相似文献   
1000.
PURPOSE: Data are used to examine current and future conditions important to the private practice of prosthodontics. A concern is raised as to whether the future supply of prosthodontists is in sync with the dynamics of the US population and patient population. MATERIALS AND METHODS: Four trends are examined using data from various sources. The trends include: (1) growth in the number of private practicing prosthodontists, (2) projections of the future number of private practicing prosthodontists, (3) first year enrollment in dental schools, and (4) enrollments and graduates in residency programs. RESULTS: The number of private practicing prosthodontists has increased modestly over the past 21 years, growing 1.33% per year. The number of private practitioners is projected to reach 4,125 in 2025. A key variable in this projection is the growing number of elderly adults. While dental school enrollments have been increasing, concern is raised about the amount of exposure by students to an undergraduate curriculum in prosthodontics. There has been a general decline in enrollment in the nation's prosthodontics residency programs at the rate of -2.9% per year. An average of 181 program graduates are needed to achieve the 4125 projected number of private practitioners. CONCLUSION: Increasing demand for services from prosthodontists is supported by an increasing US population size and a growing population of elderly. Efforts to grow the number of private practicing prosthodontists will have to consider several concerns including residency program enrollments, undergraduate exposure to prosthodontics, and the overall economic returns expected from engaging in the private practice of prosthodontics. Choosing a career as a private practicing prosthodontist is a timely consideration and complimented by expected increases in demand for care and favorable financial returns to practice.  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