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   1945篇
  免费   345篇
  国内免费   1篇
耳鼻咽喉   15篇
儿科学   21篇
妇产科学   8篇
基础医学   86篇
口腔科学   1541篇
临床医学   84篇
内科学   133篇
皮肤病学   16篇
神经病学   24篇
特种医学   69篇
外科学   133篇
综合类   6篇
一般理论   1篇
预防医学   46篇
眼科学   3篇
药学   33篇
肿瘤学   72篇
  2024年   7篇
  2023年   113篇
  2022年   8篇
  2021年   30篇
  2020年   44篇
  2019年   22篇
  2018年   94篇
  2017年   106篇
  2016年   88篇
  2015年   93篇
  2014年   114篇
  2013年   103篇
  2012年   83篇
  2011年   98篇
  2010年   105篇
  2009年   125篇
  2008年   70篇
  2007年   56篇
  2006年   59篇
  2005年   41篇
  2004年   41篇
  2003年   29篇
  2002年   29篇
  2001年   37篇
  2000年   31篇
  1999年   33篇
  1998年   78篇
  1997年   52篇
  1996年   59篇
  1995年   38篇
  1994年   49篇
  1993年   41篇
  1992年   35篇
  1991年   41篇
  1990年   29篇
  1989年   34篇
  1988年   27篇
  1987年   21篇
  1986年   20篇
  1985年   18篇
  1984年   11篇
  1983年   4篇
  1982年   12篇
  1981年   9篇
  1980年   12篇
  1979年   11篇
  1978年   13篇
  1977年   4篇
  1976年   8篇
  1975年   3篇
排序方式: 共有2291条查询结果,搜索用时 140 毫秒
901.
Objectives Although large lesions of the limbs can easily be biopsied without image guidance, lesions in the spine, paraspinal area and pelvis are difficult to target, and benefit from CT guidance to improve the accuracy of targeting the lesion for biopsy purposes. A prospective study of CT-guided core needle biopsies for deep-seated musculoskeletal lesions was conducted at a referral cancer institute over a 4-year period with the aim of assessing the safety and efficacy of the procedure. Patients & methods From January 2000 to December 2003, 136 consecutive CT-guided biopsy sessions were undertaken for musculoskeletal lesions in 128 patients comprising 73 males and 55 females. The following data was recorded in all patients: demographic data, suspected clinicoradiological diagnosis, data related to core biopsy session (date, site, approach, total time required in minutes, number of cores, surgeon satisfaction with adequacy of cores), patient discomfort, complications, histopathology report and number of further sessions if material obtained during the first biopsy session was not confirmatory. The sample obtained during the biopsy session was considered inconclusive if, in the opinion of the pathologist, inadequate or non-representative tissue had been obtained. The diagnosis was considered inaccurate if the final histopathological diagnosis did not match with the biopsy diagnosis, or if subsequent clinicoradiological evaluation at follow up did not correlate with the biopsy diagnosis in those patients who were treated with modalities other than surgery. Results In 121 patients, a single session was sufficient to obtain representative material, whilst for six patients two sessions, and for one patient three sessions were necessary. The time taken for biopsy, including the pre-biopsy CT examination time, varied from 15 min to 60 min (median 30 min). For 110 bony lesions 116 sessions were required, and for 18 soft-tissue lesions 20 sessions were required. 108 biopsy sessions yielded a diagnosis, whilst 28 were inconclusive (diagnostic yield of 79.41%). Of 108 diagnostic biopsies, five were considered inaccurate (accuracy rate of 95.37%). The overall diagnostic yield and accuracy rate for bony lesions were 81.03% and 95.74%; and those for soft-tissue lesions were 70% and 92.85%. There were two complications with no permanent sequelae. Conclusion CT-guided core needle biopsy is a safe, easy, and effective technique for the evaluation of deep-seated musculoskeletal lesions, with a high rate of diagnostic yield and accuracy. It facilitates definitive therapy without the patient having to undergo a major surgical procedure for diagnosis.  相似文献   
902.
Over 20 years, 470 cases of giant cell tumor of bone diagnosed at a tertiary cancer hospital were analyzed. Male predominance (57%), predilection for bones around the knee joint (42%), and occurence in the 21- to 30-year-old age group (49.1%) with 6% being in the immature skeleton are well known facts. Accurate diagnosis was possible in 66% and 88% of cases on radiology and biopsy, respectively. Tumors measured 6 to 20 cm and, in 402 cases, showed “usual” histology comprising uniformly scattered multinucleate giant cells amidst mononuclear stromal cells, together imparting a syncitium-like appearance. Presence of osteoid, hemorrhage, and aneurysmal bone cyst–like areas; spindle cells in sheets (devoid of giant cells); or storiform pattern and intravascular osteoclasts were less common. The less common histologic features posed diagnostic difficulty in the setting of a small biopsy. Treatment included intralesional curettage (33.19%), marginal excision (4.2%), wide excision (31%), or radical surgeries (14.25%). Recurrences seen in 170 cases were multiple in 47 cases. Metastases largely to the lung were recorded in 24 cases. The histology of all the tumors, namely, primary, recurrent, or metastatic was identical. Statistical analysis using the computer software SPSS (SPSS Inc, Chicago, Ill)was performed with particular reference to the unusual histologic features vs recurrence and metastasis by χ2 test. The only statistically significant factors were occurrence in the axial skeleton vs appendicular skeleton (P = .001) and primary treatment elsewhere vs at this hospital (P = .045), each of these being associated with increased frequency for local recurrence but not metastasis.  相似文献   
903.
This paper reviews the available evidence supporting 2 commonly used methods of surgically exposing palatally ectopic canines. The closed eruption method (a bonded attachment is placed at operation and the palatal flap is sutured back intact) is compared with the open eruption method (a window of palatal mucosa is excised and the canine allowed to erupt naturally). The choice of surgical technique is reviewed in terms of the long-term periodontal implications, the rate of repeat surgery, and treatment time.  相似文献   
904.
The effects of a novel heat shock protein inhibitor, 17AAG, on established APL cell lines (NB4 and R1) were analyzed. 17AAG induces apoptosis in APL cell lines both sensitive (NB4) and resistant (R1) to ATRA after 72 h of incubation. Apoptosis occurs by a mechanism different than ATRA-mediated response, as the cells do not undergo differentiation before apoptosis. Analysis of bax and bcl-2 shows that pro-apoptotic (bax) and anti-apoptotic (bcl-2) proteins are decreased in expression after incubation with 17AAG. We believe this data supports potential clinical use of agents that target HSP90 in APL patients failing conventional therapy.  相似文献   
905.
Controlling the vertical dimension of high-angle patients without the benefit of compliance can be a challenging aspect of orthodontic treatment. This retrospective study examines the skeletal and dental effects of a modified transpalatal bar, dubbed the vertical holding appliance (VHA), which was used in an attempt to control the vertical dimension of high-angle patients. Two cephalometrically similar groups of high-angle patients (16 patients each) were compared to determine advantages from using the VHA. Group I (n = 16, pretreatment age 13.4 +/- 1.6 years) was treated with 4 premolar extractions in conjunction with the VHA cemented in place for 17.4 +/- 6.1 months. Group II (n = 16, pretreatment age 13.4 +/- 1.9 years), which was matched for age and pretreatment skeletal pattern, was treated with the Tweed technique and 4 premolar extractions. Lateral cephalometric radiographs were taken before the placement of the VHA, as well as at the end of treatment. The results showed that although y-axis increased significantly in group II (P <.05), it remained the same in group I. Within group I, the Frankfort mandibular plane angle and gonion gnathion/sella nasion angle decreased, whereas both of these values increased in group II. However, these changes were statistically insignificant. Lower anterior face height increased more in group II than in group I (P <. 05). The percentage of lower anterior face height to total anterior face height decreased in group I, whereas it increased in group II. The difference between the 2 groups was determined to be significant (P <.01). Eruption of the maxillary first molar within group I was less than in group II. No significant differences were found between groups I and II for changes in overbite.  相似文献   
906.

Background

Seborrheic dermatitis is a common chronic inflammatory skin disorder that affects the scalp and is characterized by erythema and oily scales. It could perhaps be difficult to control and could seriously degrade one's quality of life. The study's objective is to assess the effectiveness of intradermal administrations of QR678 Neo® hair growth factor therapy for the treatment of scalp seborrheic dermatitis in both men and women.

Method

Forty male and female patients with clinically diagnosed seborrheic dermatitis of the scalp in the age 18–45 years, not satisfactorily responding to standard therapy for at least 6 months, were included. 1 mL solution of QR678 Neo® was administered in the scalp skin of all patients at 3-week interval till eight sessions. Patients were advised to continue with antifungal shampoo and topical antifungal solution with steroid combination which they had been on during the treatment. Assessment of disease severity, dermoscopic evaluation, and self-assessment were done at baseline and at the end of the fourth and the eighth sessions.

Results

Improvement was observed in adherent scalp flaking score after eighth session (mean = 12) compared to baseline (mean = 60). The dermoscopic evaluation showed a noticeable difference from baseline (mean = 11) in erythema and scaling with the Seborrheic Dermatitis Scalp Severity Index tool at the end of treatment (mean = 2). A high satisfaction score was given for the efficiency in the self-assessment questionnaire.

Conclusion

Our study proved that treatment with QR678 Neo® led to an improvement in the overall scalp condition by the resolution of flaking and inflammation.  相似文献   
907.
908.
The aim of this study was to determine the direct mutagenic potential of any precipitate formed by combining sodium hypochlorite (NaOCl) and chlorhexidine (CHX). The precipitates formed by NaOCl and CHX were dissolved in 100% dimethyl sulfoxide and cultured with mutant Salmonella Typhimurium strains. The cells were observed for reverse mutation. The numbers of positive/mutated wells were statistically compared with those in the background plates using the two‐sample proportion independent t‐test. The precipitates were not found to be significantly more mutagenic than the background plates. Within the limitations of this study, the results suggest that the precipitates formed when sodium hypochlorite and chlorhexidine contact did not show mutagenic (and are therefore carcinogenic) potential.  相似文献   
909.
The success of an ocular prosthesis depends largely on the correct orientation of the iris disk. Various methods have been put forth to achieve this. This article emphasizes one such simplified method, wherein a customized scale has been used to orient the iris disk mediolaterally, superoinferiorly, and anteroposteriorly in an ocular prosthesis. A scleral wax pattern was fabricated. The customized scale was used to measure the dimension and orientation of the natural iris. These measurements were then transferred to the scleral wax pattern with the customized scale. An iris disk was fabricated using black crayon on the scleral wax pattern according to the measurements. The scleral wax pattern, including the iris disk, was then placed in the eye socket to verify its dimension and orientation. A prefabricated iris disk was modified according to the measured dimensions and transferred to the final scleral wax pattern. The transfer of these dimensions to the definitive prosthesis was achieved successfully, ultimately improving the patient's social and psychological well being.  相似文献   
910.
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