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   8729篇
  免费   572篇
  国内免费   45篇
耳鼻咽喉   66篇
儿科学   365篇
妇产科学   293篇
基础医学   1020篇
口腔科学   184篇
临床医学   886篇
内科学   1809篇
皮肤病学   222篇
神经病学   666篇
特种医学   247篇
外国民族医学   7篇
外科学   1178篇
综合类   180篇
一般理论   5篇
预防医学   791篇
眼科学   227篇
药学   615篇
  2篇
中国医学   36篇
肿瘤学   547篇
  2024年   45篇
  2023年   114篇
  2022年   196篇
  2021年   357篇
  2020年   234篇
  2019年   269篇
  2018年   356篇
  2017年   250篇
  2016年   263篇
  2015年   255篇
  2014年   390篇
  2013年   498篇
  2012年   674篇
  2011年   708篇
  2010年   380篇
  2009年   298篇
  2008年   483篇
  2007年   542篇
  2006年   466篇
  2005年   537篇
  2004年   402篇
  2003年   358篇
  2002年   300篇
  2001年   98篇
  2000年   78篇
  1999年   92篇
  1998年   43篇
  1997年   51篇
  1996年   32篇
  1995年   41篇
  1994年   27篇
  1993年   34篇
  1992年   33篇
  1991年   23篇
  1990年   30篇
  1989年   31篇
  1988年   25篇
  1987年   21篇
  1986年   27篇
  1985年   28篇
  1984年   17篇
  1983年   16篇
  1982年   20篇
  1981年   14篇
  1980年   15篇
  1979年   14篇
  1978年   23篇
  1976年   14篇
  1972年   15篇
  1969年   16篇
排序方式: 共有9346条查询结果,搜索用时 15 毫秒
51.
Retroperitoneal contamination may occur during the natural history of hydatid disease. Primary hydatid cyst of the retroperitoneum is extremely rare. The authors report a case of a giant retroperitoneal hydatid cyst. Clinicians and surgeons must be aware of this possibility and follow a policy of nonsystematic puncture of an abdominal cyst and avoid spillage during surgery. Symptoms are related to the size, location, or ensuing complications of a cyst. Its occurrence should be strongly suspected ahead of any abdominal cyst, especially in an endemic area, where it may act as a parasite. Total and careful surgical excision is the gold-standard therapy.  相似文献   
52.

Objective:

Cryptorchidism affects 1% of male births. The majority of patients with undescended testis are identified and treated in childhood, but a significant proportion of them especially in third-world countries are neglected and present late. Herein, we present our initial experience of managing impalpable testis in older children and adults with laparoscopic assistance.

Patients and Methods:

This study was conducted from 2003 through 2008 at LUMHS Jamshoro. Thirty-two patients with 40 impalpable testes were included in this study. Diagnostic laparoscopy was performed in 32 anesthetized patients. Laparoscopic-assisted orchiopexy or orchiectomy was performed in patients with intraabdominal testis. Testicular vessels and vas deferens were mobilized and after obtaining sufficient length were brought through the posterior wall of the inguinal canal by creating a neo-inguinal ring medial to the epigastric vessels after a small inguinal incision.

Results:

Of 40 impalpable testis, ultrasound localized 16 (40%) of them, and on laparoscopy, 36 (90%) were localized, 30 (75%) as intraabdominal and in 6 (15%) cases vas and vessels were entering into the internal inguinal ring (intracanalicular). The remaining 4 patients were diagnosed as having vanishing testis (anorchia). Laparoscopic orchiectomy was performed in 14 (35%) of these testes, while single-stage laparoscopic-assisted orchiopexy using Prentiss'' maneuver was performed in 16 (40%) testis. No major complications occurred. Seven testes were associated with ipsilateral hernias and were simultaneously repaired laparoscopically.

Conclusion:

Laparoscopic-assisted single-stage orchiopexy is a safe and successful procedure for intraabdominal testis in adolescents and older patients. The additional benefit of shortening the usual course of spermatic cord was beneficial to fix the testis in the scrotum without tension.  相似文献   
53.
BACKGROUND: Knowledge about Cystic Fibrosis (CF) in Egypt is very limited. The objective of this study was to screen for CF in Egyptian children with suggestive clinical features and to identify causative genetic mutations. METHODS: Sixty-one patients from the Chest Unit, Cairo University Children's Hospital, Egypt, were included. Subjects presented with persistent or recurrent respiratory symptoms, failure to thrive, diarrhea and/or steatorrhea and unexplained persistent jaundice. Patients were screened using the CF Indicatortrade mark sweat test system (PolyChrome Medical, Inc., Brooklyn Center, MN). A quantitative sweat testing was conducted on 10 of the 12 positive patients. Seven probands and one sibling underwent molecular analysis by direct DNA sequencing of the coding region and of the intronic sequences adjacent to the 27 exons of the CFTR gene. RESULTS: Of 61 patients, 12 (20%) had positive sweat chloride screening. Ten of the 12 patients underwent quantitative sweat testing and were positive. Eight CFTR sequence changes were identified in seven affected probands and two were confirmed in one sibling by direct DNA sequencing. CONCLUSION: The study results suggest that CF is more common in Egypt than previously anticipated. Larger studies are warranted to identify the incidence, molecular basis and clinical pattern of CF in the Egyptian population.  相似文献   
54.

Background and purpose

We performed a randomized study to determine the migration patterns of the Spectron EF femoral stem and to compare them with those of the Charnley stem, which is regarded by many as the gold standard for comparison of implants due to its extensive documentation.

Patients and methods

150 patients with a mean age of 70 years were randomized, single-blinded, to receive either a cemented Charnley flanged 40 monoblock, stainless steel, vaquasheen surface femoral stem with a 22.2-mm head (n = 30) or a cemented Spectron EF modular, matte, straight, collared, cobalt-chrome femoral stem with a 28-mm femoral head and a roughened proximal third of the stem (n = 120). The patients were followed with repeated radiostereometric analysis for 2 years to assess migration.

Results

At 2 years, stem retroversion was 2.3° and 0.7° (p < 0.001) and posterior translation was 0.44 mm and 0.17 mm (p = 0.002) for the Charnley group (n = 26) and the Spectron EF group (n = 74), respectively. Subsidence was 0.26 mm for the Charnley and 0.20 mm for the Spectron EF (p = 0.5).

Interpretation

The Spectron EF femoral stem was more stable than the Charnley flanged 40 stem in our study when evaluated at 2 years. In a report from the Norwegian arthroplasty register, the Spectron EF stem had a higher revision rate due to aseptic loosening beyond 5 years than the Charnley. Initial stability is not invariably related to good long-term results. Our results emphasize the importance of prospective long-term follow-up of prosthetic implants in clinical trials and national registries and a stepwise introduction of implants.Femoral stem loosening in cemented total hip arthroplasty (THA) is a multifactorial process with different mechanisms (Gruen et al. 1979, Barrack 2000). Factors such as the material, design, and surface finish are of fundamental importance for the long-term performance of cemented femoral hip implants (Scheerlinck and Casteleyn 2006). The longevity of cemented femoral stems has been related to the quality, stability, and endurance of the bonding between stem and cement (Chang et al. 1998, Scheerlinck and Casteleyn 2006). Different femoral stem designs have been developed to obtain increased fixation at this interface, since debonding between the cement and stem is an important mechanism in the initiation of loosening (Jasty et al. 1991).The satin-finish Spectron femoral stem has been one of the best performing stems in the Swedish National Arthroplasty Register (Malchau et al. 2002). A modified, proximally roughened version of the Spectron stem, the Spectron EF (Smith and Nephew, Memphis, TN), was introduced in 1989 to enhance stem-cement bonding.The use of this implant gained increasing popularity, and in 2007 the Spectron EF stem used with the Reflection All-Poly acetabular cup (Smith and Nephew) was the most commonly used primary total hip prosthesis in Norway (Espehaug et al. 2009).The degree of migration during the first years after surgery has been shown to correlate with the long-term performance of joint prostheses (Kärrholm et al. 1994, Kobayashi et al. 1997). Radiostereometric analysis (RSA) allows the accurate measurement of implant movement and has been extensively used for measurement of the in vivo migration of implants (Kärrholm et al. 1997).An earlier prospective randomized study reported an increased revision rate of the Charnley stem compared to the satin-finished Spectron stem (Garellick et al. 1999). In the present randomized, controlled clinical trial we wanted to evaluate the early migration of the successor to this stem, the Spectron EF stem and to compare it to that of the Charnley stem using RSA. The null hypothesis was that the migration of the Spectron EF stem was equal to that of the Charnley prosthesis (DePuy International Ltd., Leeds, UK), which has the longest follow-up and the largest volume of documentation of implants used for primary total hip arthroplasty (Aamodt et al. 2004).  相似文献   
55.
Dural arteriovenous fistulas (DAVFs) of the anterior condylar vein are an uncommon but important subset of fistulas occurring at the skull base that can be confused with DAVFs of the marginal sinus on angiography. MR angiography source images can document the intraosseous extent and the relationship to the hypoglossal canal of this type of fistula, which can have significant clinical implications. We present the imaging features of angiography, CT, and MR angiography of three cases of DAVFs localized to the anterior condylar vein and within the hypoglossal canal, which were confirmed by source images from MR angiography. Transvenous coil embolization was curative in two of three cases and would seem to be the treatment of choice when venous access is available.  相似文献   
56.
57.
Overexpression of wound healing-promoting factors such as transforming growth factor-1 (TGF-beta1) and insulin-like growth factor-1 (IGF-1) during the healing process has been implicated in the development of dermal fibrosis in patients following thermal injury, surgical incision, and deep trauma. However, the mechanism through which the expression of these two fibrogenic factors is slowed down and/or abrogated in the late stages of the healing process is not known. Here, we hypothesize that keratinocyte-releasable factors counteract the fibrogenic role of both IGF-1 and TGF-beta1 in fibroblasts. To test this hypothesis, the levels of collagenase (MMP-1), as an index for extracellular matrix degradation, in dermal fibroblasts in response to either keratinocyte-conditioned medium (KCM) or our recently identified keratinocyte-releasable stratifin in the presence and absence of either IGF-1, TGF-beta1, or both were evaluated. The results of Northern analysis showed a significant increase in collagenase mRNA expression in cells treated with KCM in the presence of both IGF-1 and TGF-beta1. The effect was, at least in part, due to keratinocyte-derived stratifin that was present in KCM. This was ascertained as the levels of MMP-1 mRNA were markedly reduced when cells were treated with stratifin-immuno-depleted KCM. The results of Western blot analysis showed an increase in the level of MMP-1 protein in stratifin-treated fibroblasts and this was consistent with the level of MMP-1 mRNA expression detected by Northern analysis. However, in contrast to KCM, whose efficacy on MMP-1 expression was modestly reduced by either IGF-1 and TGF-beta1, or a combination of both, these factors abrogated the MMP-1 stimulatory effect of stratifin in fibroblasts. In summary, the results of this study revealed that both stratifin and KCM stimulate the expression of MMP-1-in fibroblasts and this effect can be abrogated by either IGF-1, TGF-beta1, or a combination of both.  相似文献   
58.
Multi-detector computed tomography (MDCT) has become an alternative to coronary angiography in diagnosis of graft occlusion and stenosis after coronary artery bypass. A literature search was performed for studies comparing angiography to 8-slice, 16-slice, and 64-slice MDCT in the assessment of coronary grafts. In assessing occlusion, 14 studies produced pooled sensitivity of 97.6%, specificity of 98.5%, diagnostic odds ratio of 934.2, area under the curve of 0.996, and Q* of 0.977. Ninety-six percent of all grafts were visualized for occlusion assessment. Beta blockers, symptomatic status, and postoperative period did not significantly affect diagnostic performance. Stenosis assessment produced sensitivity of 88.7% and specificity of 97.4%. Eighty-eight percent of patent grafts could be assessed for stenosis. The diagnostic accuracy of MDCT approaches angiography for diagnosing graft occlusion and stenosis in patients with venous and arterial coronary bypass grafts. Our findings show that cardiac surgeons will need to interpret MDCT images of both native and grafted vessels soon in preparation for primary or re-do coronary bypass grafting procedures.  相似文献   
59.
Despite documented superiority of positron emission tomography over other investigative modalities in the preoperative staging of non-small cell lung cancer, a proportion of patients will have an inaccurate staging of their mediastinal nodes. The aim of this retrospective review is to analyse the clinicopathological factors responsible for inaccurate nodal staging by integrated PET-CT. A total of 100 consecutive patients with histologically proven non-small cell lung cancer underwent staging with PET-CT prior to lung resection. Thirty-three patients, inaccurately staged by PET-CT, were analysed. Univariate analysis identified the following as significant in causing inaccurate nodal staging: history of tuberculosis (P=0.039) and non-insulin dependant diabetes (P=0.014). In multivariate analysis, we have identified the following as independent factors in causing inaccurate staging of mediastinal lymph nodes: rheumatoid arthritis, non-insulin dependent diabetes, history of tuberculosis, presence of atypical adenomatous hyperplasia and pneumonia (P<0.05). The highest rate of inaccuracy in mediastinal nodal staging was in nodal station 4 (11%, P=0.01) followed by station 7 (10%, P=0.02) and station 9 (3.5%, P=0.01). Interpretation of PET-CT staging of the mediastinum in patients with a history of the above should be with caution, as the incidence of false upstaging and down staging in these subgroups is high. Vigilance of such factors may improve the accuracy of PET-CT in staging mediastinal lymph nodes. Histological confirmation should always be sought.  相似文献   
60.
Background The aim of the present study was to identify the clinicopathological factors affecting locoregional recurrence (LRR) in patients with clinical stage IIIB noninflammatory breast cancer (NIBC). Methods The records of 120 stage IIIB NIBC patients treated with neoadjuvant chemotherapy (NAC) and then modified radical mastectomy followed by radiotherapy were evaluated. In this retrospective cohort, the effects of age, menopausal status, clinical tumor size, clinical response to NAC, pathological axillary status, number of positive axillary lymph nodes, pathological response to NAC, grade, lymphovascular invasion, estrogen receptor status, progesterone receptor status, Her-2-neu status, and p53 status on LRR were evaluated by univariate and multivariate analyses. Results The clinical response rate of 120 patients was 79.2% (17.5% complete and 61.7% partial), with a complete pathological response rate of 12.5%. The median follow-up was 28 months (range: 10–74 months). The LRR rate was 13.3%. Based on the univariate analysis, the clinical tumor size, clinical response rate, pathological axillary status, four or more positive axillary lymph nodes, lymphovascular invasion, and estrogen receptor status were factors that significantly affected LRR. In the multivariate analysis, however, only the clinical response rate and the number of positive axillary lymph nodes were found to be statistically significant independent factors. Conclusions Effective local control of disease can be achieved in patients with stage IIIB NIBC using a combination of NAC, surgery, and radiotherapy. However, a worse clinical response after chemotherapy and four or more positive axillary lymph nodes affect LRR negatively in these patients.  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