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   22845篇
  免费   2096篇
  国内免费   23篇
耳鼻咽喉   228篇
儿科学   607篇
妇产科学   587篇
基础医学   2674篇
口腔科学   404篇
临床医学   2362篇
内科学   4630篇
皮肤病学   384篇
神经病学   2159篇
特种医学   785篇
外国民族医学   3篇
外科学   3454篇
综合类   516篇
一般理论   43篇
预防医学   2458篇
眼科学   309篇
药学   1574篇
中国医学   30篇
肿瘤学   1757篇
  2021年   320篇
  2020年   203篇
  2019年   397篇
  2018年   497篇
  2017年   344篇
  2016年   317篇
  2015年   405篇
  2014年   567篇
  2013年   847篇
  2012年   1166篇
  2011年   1193篇
  2010年   742篇
  2009年   662篇
  2008年   1114篇
  2007年   1200篇
  2006年   1204篇
  2005年   1175篇
  2004年   1075篇
  2003年   1005篇
  2002年   922篇
  2001年   609篇
  2000年   641篇
  1999年   569篇
  1998年   263篇
  1997年   191篇
  1996年   211篇
  1995年   234篇
  1994年   178篇
  1993年   171篇
  1992年   423篇
  1991年   416篇
  1990年   364篇
  1989年   367篇
  1988年   338篇
  1987年   326篇
  1986年   291篇
  1985年   306篇
  1984年   265篇
  1983年   221篇
  1982年   172篇
  1981年   149篇
  1979年   241篇
  1978年   177篇
  1977年   143篇
  1975年   141篇
  1974年   149篇
  1973年   192篇
  1972年   189篇
  1971年   161篇
  1969年   148篇
排序方式: 共有10000条查询结果,搜索用时 250 毫秒
61.
The purpose of this study was threefold: (1) to report the proportion of dental practitioners adhering to the 1987 Centers for Disease Control (CDC) procedures for using infection control techniques (ICTs); (2) to identify attitudes toward infection control and disease; and (3) to establish whether certain practitioner characteristics or use of certain ICTs were related to willingness to treat HIV-positive patients, willingness to volunteer for an HIV specialty clinic outside of regular practice, vaccination against hepatitis B, and a felt need for a specialty clinic within the practice to treat HIV patients effectively. A survey of approximately 3,800 members of a major metropolitan dental society found that 89 percent of respondents regularly used at least one CDC ICT beyond routine medical histories. Ninety-one percent indicated a moderate to extreme change in attitude toward the risks of infectious diseases and the regular use of ICTs (80.2% identified AIDS as the major factor in this change). Twenty-seven percent indicated that they would knowingly treat HIV-positive patients. No differences were found among practitioners willing to treat HIV-infected patients and those unwilling to treat these patients in terms of adherence to the CDC ICT recommendations for dentists. Statistical association between ICT use and other practitioner response variables are discussed.  相似文献   
62.
Fifty one subjects who had pain involving the temporomandibular joint were evaluated using multidirectional tomography, arthrography, conventional nuclear scanning, and single photon emission computed tomography (SPECT) to assess the association of arthritis of the temporomandibular joint with internal derangements related to meniscal dysfunction. Five (56%) of the nine subjects who had normal arthrograms and normal multidirectional tomograms had SPECT scans that were positive for osseous changes. Twenty-two subjects (27 temporomandibular joints) were diagnosed by arthrography to have meniscal displacement with reduction. Multidirectional tomograms of the 27 joints were positive for osseous changes in five (18%) joints, whereas SPECT scans were positive in nine (70%) joints. Twenty subjects (20 temporomandibular joints) had an arthrographic diagnosis of meniscal displacement without reduction. Multidirectional tomograms of the 20 joints were positive for osseous changes in 14 (70%) joints, and SPECT scans were positive in 16 (80%) joints (P less than 0.001 vs control group). Initial observations with SPECT indicate it is a promising imaging method for detecting and staging osseous disease of the TMJ related to meniscal dysfunction.  相似文献   
63.
Factitious disease is often manifested in the head and neck region. It is only when the oral and maxillofacial surgeon is aware of the existence of this syndrome and has been unable to correlate a patient's history and signs and symptoms with known diseases that factitious illness may be suspected as the diagnosis. Three case histories that help to demonstrate the variety of ruses used by patients to feign illness are presented. The expertise of a psychiatrist will often help to substantiate the diagnosis, but in many instances the main aspects of treatment will remain in the hands of the original clinician. It is important for clinicians to realize that patients with chronic factitious illness are extremely manipulative and unwilling to admit to their fabrications.  相似文献   
64.
This method of fabrication of an immediate nasal prosthesis has distinct advantages which recommend its use. These are (1) the use of an RTV silicone rubber impression as the refractory cast cuts fabrication time to minutes rather than hours, as compared with other methods of fabricating a nasal prosthesis; (2) the RTV silicone is permanent and stable and provides an exact reproduction of the part to be excised; (3) the initial RTV silicone impression may be used during fabrication of the definitive prosthesis as the mold for production of a wax sculpting model; (4) PVC prostheses offer a unique advantage of being soft enough for trimming with scissors at the time of surgery and are flexible and tissue-compatible; and (5) psychological trauma is minimized and the patient is better prepared for a definitive prosthetic restoration.  相似文献   
65.
66.
The purpose of this study was to evaluate the effect of unilateral disk displacement with reduction (UDDR) on the skeletal and dental pattern of affected individuals. There were 18 symptomatic female patients and 46 asymptomatic normal female volunteers. All study participants had bilateral high-resolution magnetic resonance scans in the sagittal (closed and open) and coronal (closed) planes to evaluate the temporomandibular joints. Linear and angular cephalometric measurements were taken to evaluate the skeletal, denture base, and dental characteristics of the two groups. Analysis of variance was used to compare the symptomatic with the control subjects. A few skeletal differences were found. There was an overall reduction in length of the anterior (S-Na) and posterior (S-Ba) cranial base measurements in the UDDR group. The cranial base angle was also increased. Both upper and lower dentures bases were retropositioned. The posterior ramal height (Ar-Go) was shorter in the symptomatic group. This study showed that alterations in skeletal morphology may be associated with UDDR. The mechanisms that produce DD or the mechanisms that cause this skeletal alteration are yet to be clarified. This study suggests that subjects with UDDR may manifest altered craniofacial morphology. The clinician should be aware of this possibility, especially for growing patients.  相似文献   
67.
The purpose of this study was to evaluate the effect of bilateral disk displacement without reduction (BDDN) on the skeletal and dental pattern of affected individuals. There were 59 symptomatic female patients and 46 asymptomatic normal female volunteers. All study participants had bilateral high-resolution magnetic resonance imaging scans in the sagittal (closed and open) and coronal (closed) planes to evaluate the temporomandibular joints. Linear and angular cephalometric measurements were taken to evaluate the skeletal, denture base, and dental characteristics of the two groups. A smaller cranial base length (Ba-Na) was found in the symptomatic group. The facial plane angle was smaller, and the angle of convexity was larger because of the retropositioned mandible. The lower denture base was also retruded as shown by the smaller SNB angle. The BDDN group exhibited a larger overjet. The mandibular plane angle was steeper, the Y-axis was more vertical (S-Gn to FH), the posterior ramal height (Ar-Go) was shorter, and the angle between the mandibular and the palatal plane (PP to MP angle) was increased in the symptomatic group. No significant dental differences were found. This study showed that alterations in skeletal morphology might be associated with BDDN. This study suggests that subjects with BDDN may manifest altered craniofacial morphology. The clinician should be aware of that possibility, especially for the growing patients and the surgical candidates.  相似文献   
68.
69.
BACKGROUND: Previous studies have shown a limited potential for bone augmentation following guided bone regeneration (GBR) in horizontal alveolar defects. Surgical implantation of recombinant human bone morphogenetic protein-2 (rhBMP-2) in an absorbable collagen sponge carrier (ACS) significantly enhances bone regeneration in such defects; however, sufficient quantities of bone for implant dentistry are not routinely obtained. The objective of this study was to evaluate the potential of rhBMP-2/ACS to enhance GBR using a space-providing, macro-porous expanded polytetrafluoroethylene (ePTFE) device. METHODS: Bilateral, critical size, supra-alveolar, peri-implant defects were surgically created in four Hound Labrador mongrel dogs. Two turned and one surface-etched 10-mm titanium dental implant were placed 5 mm into the surgically reduced alveolar ridge creating 5-mm supra-alveolar defects. rhBMP-2/ACS (rhBMP-2 at 0.2 mg/ml) or buffer/ACS was randomly assigned to left and right jaw quadrants in subsequent animals. The space-providing, macro-porous ePTFE device was placed to cover rhBMP-2/ACS and control constructs and dental implants. Gingival flaps were advanced for primary wound closure. The animals were euthanized at 8 weeks postsurgery for histologic and histometric analysis. RESULTS: Bone formation was significantly enhanced in defects receiving rhBMP-2/ACS compared to control. Vertical bone gain averaged (+/- SD) 4.7 +/- 0.3 and 4.8 +/- 0.1 mm, and new bone area 10.3 +/- 2.0 and 8.0 +/- 2.5 mm2 at turned and surface-etched dental implants, respectively. Corresponding values for the control were 1.8 +/- 2.0 and 1.3 +/- 1.3 mm, and 1.8 +/- 1.3 and 1.2 +/- 0.6 mm2. Bone-implant contact in rhBMP-2-induced bone averaged 6.4 +/- 1.4% and 9.6 +/- 7.5% for turned and surface-etched dental implants, respectively (P=0.399). Corresponding values for the control were 14.6 +/- 19.4% and 23.7 +/- 9.7% (P=0.473). Bone-implant contact in resident bone ranged between 43% and 58% without significant differences between dental implant surfaces. CONCLUSIONS: rhBMP-2/ACS significantly enhances GBR at turned and surface-etched dental implants. The dental implant surface technology does not appear to substantially influence bone formation.  相似文献   
70.
This study compared the clinical performance of a polyacid-modified resin composite and a resin-modified glass-ionomer restorative material over two years. Thirty-four pairs of restorations of Compoglass and Fuji II LC were placed in caries-free cervical erosion/abfraction lesions without tooth preparation. Restorations were clinically evaluated at baseline, 6, 12, 18 and 24 months using modified Ryge/USPHS criteria. A significantly higher incidence of failed restorations was found with the polyacid-modified resin composite (p < 0.05).  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