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   4768篇
  免费   305篇
  国内免费   41篇
耳鼻咽喉   52篇
儿科学   159篇
妇产科学   41篇
基础医学   638篇
口腔科学   80篇
临床医学   352篇
内科学   1287篇
皮肤病学   67篇
神经病学   311篇
特种医学   231篇
外科学   769篇
综合类   47篇
一般理论   1篇
预防医学   141篇
眼科学   166篇
药学   185篇
中国医学   10篇
肿瘤学   577篇
  2024年   6篇
  2023年   59篇
  2022年   101篇
  2021年   242篇
  2020年   118篇
  2019年   153篇
  2018年   220篇
  2017年   148篇
  2016年   159篇
  2015年   151篇
  2014年   206篇
  2013年   256篇
  2012年   372篇
  2011年   370篇
  2010年   185篇
  2009年   152篇
  2008年   296篇
  2007年   268篇
  2006年   239篇
  2005年   275篇
  2004年   267篇
  2003年   207篇
  2002年   193篇
  2001年   46篇
  2000年   25篇
  1999年   31篇
  1998年   39篇
  1997年   33篇
  1996年   25篇
  1995年   18篇
  1994年   22篇
  1993年   17篇
  1992年   23篇
  1991年   20篇
  1990年   17篇
  1989年   15篇
  1988年   18篇
  1987年   12篇
  1986年   10篇
  1985年   10篇
  1984年   10篇
  1983年   8篇
  1982年   9篇
  1981年   10篇
  1980年   6篇
  1979年   11篇
  1977年   6篇
  1975年   6篇
  1973年   4篇
  1970年   6篇
排序方式: 共有5114条查询结果,搜索用时 62 毫秒
991.
Osteonecrosis of the jaw is a severe new complication in cancer patients with bone metastases receiving bisphosphonate. Currently, there is no effective treatment for bisphosphonate-related osteonecrosis of the jaw, and the pathogenesis of this complication has not been completely elucidated. It has been shown that a potential risk factor for the complication is dentoalveolar trauma including extraction of teeth during bisphosphonate therapy. Attention should be paid to dental care in patients prior to the initiation of bisphosphonate therapy, and extraction of teeth during bisphosphonate therapy should be avoided to prevent this complication. Therefore, the communication between general physicians prescribing bisphosphonate and dentists is important.  相似文献   
992.
A major early event in papillary thyroid carcinogenesis is constitutive activation of the mitogen-activated protein kinase signaling pathway caused by alterations of a single gene, typically rearrangements of the RET and NTRK1 genes or point mutations in the BRAF and RAS genes. In childhood papillary thyroid cancer, regardless of history of radiation exposure, RET/PTC rearrangements are a major event. Conversely, in adult-onset papillary thyroid cancer among the general population, the most common molecular event is BRAF(V600E) point mutation, not RET/PTC rearrangements. To clarify which gene alteration, chromosome aberration, or point mutation preferentially occurs in radiation-associated adult-onset papillary thyroid cancer, we have performed molecular analyses on RET/PTC rearrangements and BRAF(V600E) mutation in 71 papillary thyroid cancer cases among atomic bomb survivors (including 21 cases not exposed to atomic bomb radiation), in relation to radiation dose as well as time elapsed since atomic bomb radiation exposure. RET/PTC rearrangements showed significantly increased frequency with increased radiation dose (P(trend) = 0.002). In contrast, BRAF(V600E) mutation was less frequent in cases exposed to higher radiation dose (P(trend) < 0.001). Papillary thyroid cancer subjects harboring RET/PTC rearrangements developed this cancer earlier than did cases with BRAF(V600E) mutation (P = 0.03). These findings were confirmed by multivariate logistic regression analysis. These results suggest that RET/PTC rearrangements play an important role in radiation-associated thyroid carcinogenesis.  相似文献   
993.
Many surgeons apply povidone-iodine (PVP-I) to the skin around an incision before closing a wound to reduce wound infection rates. However, the effectiveness of this procedure has not been proven. Forty-seven cases of gastric surgery and 60 cases of colorectal surgery performed at Kanto Medical Center between July 2004 and December 2004 were randomly assigned to the group with PVP-I or the group without PVP-I. Wound infection and surgical site infection (SSI) rates were compared between these two groups. Applying PVP-I was effective in eliminating skin contamination, as cultures became negative in all cases after applying PVP-I. However, this study could not demonstrate the reduction of wound infection or SSI in the group with PVP-I, possibly because the number of cases in this study was too small to make a difference. Subcutaneous tissue contamination was considered a more important factor than skin contamination in causing wound infection.  相似文献   
994.
A large cervico-mediastinal tracheal defect in a 72-year-old man as a result of surgery for thyroid carcinoma with tracheal invasion and mediastinal lymph node metastasis was reconstructed using a pectoralis major myocutaneous flap and free costal cartilage grafts. The tracheal defect (55 mm x 30 mm) was located at the thoracic inlet adjacent to the major mediastinal vessels. Our reconstructive procedure was a two-staged surgery. In the first stage, a pectoralis major myocutaneous flap was transferred to the neck to provide a well-vascularized recipient bed for free costal cartilage grafts and to cover large vessels. Two pieces of free costal cartilage were grafted on the pectoralis major myocutaneous flap, one for the lateral wall reconstruction and the other prefabricated for the anterior wall of the trachea. In the second stage, the re-vascularized cartilage graft for the anterior wall of the trachea with overlying skin was rotated onto the trough of the remaining trachea and the closure of the tracheal defect was completed. We conclude that free cartilage grafts for the reconstruction of a large cervico-mediastinal tracheal defect can be safely used when they are combined with well-vascularized pectoralis major myocutaneous flaps.  相似文献   
995.
Allergic diseases have been increasing in prevalence in developed countries, including Japan. The aim of the present report was to determine the prevalence of allergies in Wakayama prefecture using an epidemiological study. In total, 759 first-year students attending junior high school in Hidaka country, Wakayama prefecture, were surveyed. The results for 699 cases were then analyzed. A questionnaire regarding allergic diseases, specific IgE measurements performed using a MAST26 system (Hitachi Co., Ltd.), and total serum IgE levels measured using RIST (Pharmacia Co., Ltd.) were performed. The prevalence (present + past) of various allergic diseases was 37.9%. The prevalence of rhinitis, including pollinosis, was 31.0%, while that of atopic dermatitis was 26.2% and bronchial asthma was 11.3%. The positive rates for specific IgE antibodies against Japanese cedar pollen was 48.6%. The positive rate for Dermatophagoides farinae, timothy and housedust II were 44.2%, 29.6%, and 28.9%, respectively. Statistically significant differences were recognized between the students with allergic rhinitis, atopic dermatitis, allergic conjunctivitis or bronchial asthma and positive results for D. farinae, housedust II, cedar pollen, Penicillium, Cladosporium, or Aspergillus-specific antibodies. Regarding family history (two generations), a statistical significant difference between family history and positivity for specific IgE antibodies like D. farinae, housedust II, ragweed, cedar pollen or Cladosporium was observed. The total IgE titer was correlated with the number of positive allergen items. The increasing prevalence of various allergic diseases in developed countries remains a mystery, but the hygienehypothesis has attracted some attention. The findings of this epidemiologic study will contribute to basic data on the increasing prevalence of various allergic diseases.  相似文献   
996.
Clara cell secretory protein (CC10) is an important anti-inflammatory mediator in the adult lung, but its role in newborn pulmonary protection is uncertain. We examined the early postnatal behavior of CC10 in newborn serum and tracheal fluid and hypothesized that CC10 production is positively influenced by gestation. Blood from 165 infants from the first, third/fourth, and seventh days of life (gestational ages: 23-29 wk, 30-36 wk, >36 wk) and tracheal fluid (TF) from the first day of life from 32 ventilated infants were analyzed for CC10. Surfactant proteins A (SPA) and B (SPB) were also analyzed from the blood of a subgroup of infants. Serum CC10 on day 1 was highest in term infants (69.4 ng/mL), followed by moderately preterm (55.8 ng/mL), and then extremely preterm infants (median 42.1 ng/mL). Term infants also had higher tracheal fluid CC10 than preterm infants. (20.152 ng/mL versus 882 ng/mL). Mechanical ventilation increased serum CC10 only in moderately preterm infants, and only on d 1 [68.4 ng/mL versus 42.1 ng/mL (nonventilated moderately preterm infants)]. Serum CC10 decreased progressively by the end of the first week in all infants, in contrast to SPA and SPB, which increased. Our results show that CC10 is detectable in the blood of newborn infants and that a production surge occurs at birth. This surge is more pronounced in term infants and may confer them with superior extrauterine pulmonary protection compared with preterm infants.  相似文献   
997.
998.
OBJECTIVES: Specific potential determinants of infant pain response were assessed in the context of a 4- or 6-month immunization injection. The distal influences of gender, gestational and current age, temperament, and early nociceptive stimuli were considered, as well as the proximal influences of parental and nurse coping-promoting statements within the treatment room. STUDY DESIGN: An observational study design was used. Pain responses in 93 infants receiving an immunization injection were videoed and coded using the Neonatal Facial Coding System (NFCS) and duration of crying was recorded. Parent and nurse vocalizations were coded using the Child-Adult Medical Procedure Interaction Scale-Revised. RESULTS: A multiple regression analysis evaluated the influence of the 5 distal and 2 proximal factors on NFCS scores, and found parental coping-promoting statements in the 30 s period before the injection to have the strongest effect on facial pain response (p<0.01). Parents made significantly more coping-promoting statements (p<0.05), and generally talked more (p<0.05), to female infants than male infants. CONCLUSIONS: The findings suggest that parental behavior in the treatment room has a key role in influencing how infants respond to painful procedures.  相似文献   
999.
1000.
AIM: To evaluate expression of proangiogenic matrix metalloproteinases (MMP) 2 and 9 at distinct intervals after verteporfin photodynamic therapy (PDT) in human choroidal neovascular membranes (CNV) secondary to age-related macular degeneration (AMD). METHODS: Retrospective review of an interventional case series of 49 patients who underwent removal of CNV. Twenty-six patients were treated with PDT 3 to 383 days prior to surgery. Twenty-three CNV without previous treatment were used as controls. CNV were stained for CD34, cytokeratin 18, endostatin, MMP-2 and MMP-9 by immunohistochemistry. RESULTS: CNV without previous therapy disclosed MMP-2, MMP-9 in RPE-Bruch's membrane, vessels and stroma in different intensities. Three days after PDT, MMP-9 expression was significantly weaker in stroma (p = 0.0019). Endostatin was significantly reduced in vessels (p<0.001). At longer post-PDT intervals, a significant increase of MMP-9 in stroma (p = 0.037) and of endostatin in RPE-Bruch's membrane (p = 0.02), vessels (p = 0.005) and stroma (p<0.001) were disclosed. No significant changes in MMP-2 expression were detected. CONCLUSIONS: PDT induced an early, temporary decrease in MMP-9 and endostatin expression. At longer intervals, MMP-9 increase is possibly associated with the angiogenic process responsible for recurrence after PDT. MMP-9, however, acts as a double-edged sword by concomitant induction of endostatin, an endogenous inhibitor of angiogenesis.  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