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   121355篇
  免费   7097篇
  国内免费   1587篇
耳鼻咽喉   1586篇
儿科学   3035篇
妇产科学   4179篇
基础医学   18732篇
口腔科学   3675篇
临床医学   9522篇
内科学   22170篇
皮肤病学   2485篇
神经病学   8158篇
特种医学   4081篇
外国民族医学   3篇
外科学   17000篇
综合类   5251篇
一般理论   36篇
预防医学   8904篇
眼科学   2874篇
药学   10391篇
中国医学   837篇
肿瘤学   7120篇
  2021年   1154篇
  2019年   1157篇
  2018年   1733篇
  2017年   1248篇
  2016年   1294篇
  2015年   1526篇
  2014年   2000篇
  2013年   2608篇
  2012年   3779篇
  2011年   4029篇
  2010年   2399篇
  2009年   2122篇
  2008年   3498篇
  2007年   3754篇
  2006年   3691篇
  2005年   3258篇
  2004年   3050篇
  2003年   2838篇
  2002年   2704篇
  2001年   6741篇
  2000年   6931篇
  1999年   5708篇
  1998年   1842篇
  1997年   1386篇
  1996年   946篇
  1995年   870篇
  1992年   3736篇
  1991年   3809篇
  1990年   3551篇
  1989年   3555篇
  1988年   3431篇
  1987年   3280篇
  1986年   3090篇
  1985年   2969篇
  1984年   2051篇
  1983年   1793篇
  1982年   986篇
  1979年   1909篇
  1978年   1184篇
  1977年   987篇
  1976年   918篇
  1975年   1191篇
  1974年   1360篇
  1973年   1413篇
  1972年   1357篇
  1971年   1250篇
  1970年   1137篇
  1969年   1121篇
  1968年   1024篇
  1967年   897篇
排序方式: 共有10000条查询结果,搜索用时 10 毫秒
81.
OBJECTIVE: This study was designed to assess the effects of a manual stimulating distraction device (Isoflex referred to as Manual Stimulation Distraction Device or MSDD) for reducing pain and anxiety experienced with standard dental local anesthetic injections. Additionally, the memory recall effects on injection pain and anxiety were also explored. METHODOLOGY: Patients from different dental clinics were identified by their practitioners as requiring dental procedures under local anesthesia, in the same area on both sides of the mouth. A local anesthetic solution was injected on either the left or right side at different times by random selection; one side using MSDD, while the opposite side used a solution without MSDD. Each patient acted as his or her own symmetrical split-mouth control. The same dentist administered both injections, using identical technique and equipment for each side. Forty-six patients used the MSDD first with the injection, while 54 used MSDD second when they received the injection. Using 10-point visual analogue nominal and ordinal scales, pain and stress were recorded by the patient each time after receiving the injection. The results were pooled and subjected to statistical analysis. Student's paired t-test was employed to test for significant differences in pain and anxiety (stress) when injections were administered with and without MSDD. RESULTS: Results showed significant reductions in perceived pain and stress from local analgesia injections (p < 0.001) when MSDD was used. There was no correlation of pain reduction with age, gender, upper or lower jaw, with or without MSDD. There was a trend for pain and stress to be scored higher for those subjects who had a lower period since the first injection (POFI) scores. This was attributed to recent memory of pain, as POFI scores over one week were significantly lower (p < 0.05). Stress reduction for POFI scores greater than one week proved to be non-significant (p = 0.099). CONCLUSION: In this study, MSDD was effective at reducing pain and stress experienced with local regional analgesic injections.  相似文献   
82.
The quantity of alveolar bone decreases mainly because of periodontal disease or loss of teeth causing bone resorption in both vertical and horizontal directions. Inadequate width of the alveolar ridge affects many parameters of implants placement and the final restoration. Placement of an implant in a narrow ridge without bone graft may harm the final esthetics and the long-term success of the implant rehabilitation. The purpose of this article is to review the basic principles of bone grafting and to discuss various grafting techniques for widening of the narrow ridge.  相似文献   
83.
1354 freshmen have been investigated to discover the relationship between dental diseases and environments,living habits and personal sanitary conditions,because urban young men like sweet foods and snacks,the incidence of caries is greater in the cities than in the country,more people with tetracycline discolored tooth live in urban areas than in the rustic ones,which is due to dense living conditions, vulnerable to respiratory organs disease,medical conditions and convenience of taking tetracycline when ill;on the other hand,gingivitis is more common within the country students than within the city students,for those students from the country are used to brush their tooth after adolescence and usually have more dental calculus which is harmful to the gingiva.More than half of the investigated freshmen are ignorant of correct method of brushing and oral health and that is important factors of high rate of dental disease,according to the above reasons,the effective measures should educated to prevent dental disease.  相似文献   
84.
85.
To address the question of what role growth hormone may have in stimulating tooth formation, the distribution of its receptor/binding protein in developing rat incisors and molars was studied immunocytochemically using well-characterized monoclonal antibodies. Ten female 45-day-old Wistar rats were perfused with 4% paraformaldehyde. Five-microns paraffin sections of the growing end of maxillary incisors and molars were cut, deparaffinized and incubated with mouse anti-growth hormone receptor antibodies or control antibodies. A three-layer streptavidin peroxidase technique was used to detect bound antibody. Immunoreaction product was associated primarily with the cytoplasm of cells at certain stages of differentiation. Dividing cells, differentiating preameloblasts and preodontoblasts, secretory ameloblasts and odontoblasts showed immunoreactivity. Undifferentiated dental epithelium cells, stellate reticulum, external dental epithelial cells, mature odontoblasts, and most of cells in the dental papilla were non-reactive. However, at certain stages of tooth development, the stratum intermedium and the external dental epithelium also stained positively. The presence of growth hormone receptor/binding protein in tooth cells at different stages of their development indicates that growth hormone may influence cell proliferation, differentiation and differentiated functions of ameloblasts, odontoblasts and cementoblasts independent of a systemic mediator, and thus may be involved in stimulating odontogenesis directly.  相似文献   
86.
The jaw-opening (digastric) reflex was elicited by electrical stimulation of oral mucosa in miniature pigs (Sus scrofa) varying in age from 5 days premature to 101 days post-term. The latency of reflex electromyographic activity varied between 12–14 ms in the most immature animals and 9–11 ms in the oldest animals. The very long-latency digastric responses found in the immature young of nesting mammals were not seen in the relatively precocious young of this species.  相似文献   
87.
Lactate dehydrogenase (LDH) isoenzymes of 15 clinically dormant radicular cysts were examined. A fragment from each cyst was homogenized, centrifuged and the LDH isoenzymes in the supernatant were separated by cellulose acetate paper electrophoresis. The strongest bands of the cysts were LDH-5 and LDH-4.  相似文献   
88.
The structural similarity of eugenol with capsaicin suggests that these two agents may share molecular mechanisms to produce their effects. We investigated the effects of eugenol in comparison with those of capsaicin using whole-cell patch clamp and Fura-2-based calcium-imaging techniques in a heterologous expression system and with sensory neurons. In vanilloid receptor 1 (VR1)-expressing human embryonic kidney (HEK) 293 cells and trigeminal ganglion (TG) neurons, eugenol activated inward currents, whereas capsazepine, a competitive VR antagonist, and ruthenium red (RR), a functional VR antagonist, completely blocked eugenol-induced inward currents. Moreover, eugenol caused elevation of [Ca(2+)](i), and this was completely abolished by both capsazepine and ruthenium red in VR1-expressing HEK 293 cells and TG neurons. Our results provide strong evidence that eugenol produces its effects, at least in part, via VR1 expressed by the sensory nerve endings in the teeth.  相似文献   
89.
Relatively little is known about the formation of the acquired enamel pellicle other than that it involves the selective adsorption of specific proteins from oral fluids. Previous studies on the identification of pellicle components have relied largely on immunological or enzymatic detection and have been hampered by the fact that only minute quantities of pellicle can be removed from tooth surfaces. The present work describes an improved method of harvesting pellicle that combines mechanical and chemical removal; this approach was used to investigate systematically the desorption of in vitro pellicle components with different solutions. Eleven major in vitro pellicle proteins were identified by using a combination of electrophoretic separation and matrix-assisted laser desorption/ionization-reflectron time-of-flight mass spectrometry. A similar analysis of in vivo-formed pellicle revealed the presence of intact statherin, lysozyme, albumin and amylase. Further analysis of in vivo pellicle by liquid chromatography-electrospray ionization mass spectrometry suggested the presence of numerous low molecular-weight fragments of precursor proteins. The protein composition of in vitro whole-salivary pellicle adsorbed to hydroxyapatite and that of in vivo enamel pellicle differed for proline, the result of a reduction in the content of acidic proline-rich proteins in the in vivo samples. Unique features of the oral environment such as enzymatic activities or mineral surface properties may account for these differences between in vivo and in vitro pellicle formation.  相似文献   
90.
The use of a barrier membrane, with or without osseous allograft, has been shown to establish regeneration of osseous tissue around dental implants. Following three episodes of persistent symptomatic failed apicoectomy and subsequent tooth extraction, an osseointegrated implant was placed in a wide fenestrated defect. Demineralized freeze-dried bone allograft was covered by an occlusive expanded polytetrafluorethylene membrane. The reentry procedure revealed complete bone fill that followed the texture of the augmentation material beyond the previous buccal bony envelope.  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