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   8600篇
  免费   510篇
  国内免费   59篇
耳鼻咽喉   37篇
儿科学   210篇
妇产科学   233篇
基础医学   1254篇
口腔科学   117篇
临床医学   680篇
内科学   2224篇
皮肤病学   296篇
神经病学   771篇
特种医学   246篇
外科学   1002篇
综合类   19篇
一般理论   3篇
预防医学   436篇
眼科学   54篇
药学   571篇
中国医学   28篇
肿瘤学   988篇
  2023年   69篇
  2022年   178篇
  2021年   246篇
  2020年   156篇
  2019年   222篇
  2018年   256篇
  2017年   178篇
  2016年   197篇
  2015年   249篇
  2014年   344篇
  2013年   415篇
  2012年   621篇
  2011年   643篇
  2010年   366篇
  2009年   304篇
  2008年   493篇
  2007年   485篇
  2006年   529篇
  2005年   485篇
  2004年   439篇
  2003年   396篇
  2002年   378篇
  2001年   113篇
  2000年   114篇
  1999年   113篇
  1998年   88篇
  1997年   90篇
  1996年   77篇
  1995年   72篇
  1994年   59篇
  1993年   45篇
  1992年   81篇
  1991年   71篇
  1990年   55篇
  1989年   69篇
  1988年   65篇
  1987年   50篇
  1986年   36篇
  1985年   39篇
  1984年   29篇
  1983年   17篇
  1982年   13篇
  1980年   17篇
  1978年   14篇
  1977年   18篇
  1974年   12篇
  1973年   14篇
  1972年   14篇
  1971年   23篇
  1967年   13篇
排序方式: 共有9169条查询结果,搜索用时 15 毫秒
81.
BACKGROUND: This study compared the prevalence of co-morbidity in patients starting renal replacement therapy (RRT) between European countries and further examined how co-morbidity affects access to transplantation. METHODS: In this ERA-EDTA registry special study, 17907 patients from Austria, Catalonia (Spain), Lombardy (Italy), Norway, and the UK (England/Wales) were included (1994-2001). Co-morbidity was recorded at the start of RRT. RESULTS: The prevalence of co-morbidity was: diabetes mellitus (DM) (primary renal disease and co-morbidity) 28%, ischaemic heart disease (IHD) 23%, peripheral vascular disease (PVD) 24%, cerebrovascular disease (CVD) 14% and malignancy 11%. With exception of malignancy, the prevalence of co-morbidity was highest in Austria, but differences were small among other countries. With exception of DM, males suffered more often from co-morbidity than females. In general, the percentage of haemodialysis was higher in patients with co-morbidity, but treatment modality differed substantially between countries. Using a Cox regression with adjustment for demographics, country, year of start and other co-morbidities, the presence of each of the co-morbid conditions made it less likely [RR; 95%CI] to receive a transplant within 4 years: DM [0.79; 0.70-0.88], IHD [0.59; 0.50-0.70], PVD [0.57; 0.49-0.67], CVD [0.49; 0.39-0.61], and malignancy [0.32; 0.24-0.42]. The age, gender and year of start adjusted relative risk [95%CI] to receive a renal transplant within 4 years ranged from 0.23 [0.19-0.27] for Lombardy (Italy) to 3.86 [3.36-4.45] for Norway (Austria = reference). These international differences existed for patients with and without co-morbidity. CONCLUSIONS: The prevalence of co-morbidity was highest in Austria but differences were small among other countries. The access to a renal graft was most affected by the presence of malignancy and least affected by the presence of DM. International differences in access to transplantation were only partly due to co-morbid variability.  相似文献   
82.

Background

Most reports in the literature on botulinum toxin A (BoNTA) therapy for neurogenic detrusor overactivity (NDO) are based on the results of a single injection. Because most patients may require retreatment, the efficacy and safety of multiple injections must be addressed clearly.

Objective

To investigate the effectiveness and safety of BoNTA intradetrusorial injections in a group of spinal cord–injured (SCI) patients with refractory detrusor overactivity (DO).

Design, setting, and participants

Seventeen SCI patients were prospectively included in the study and followed up to 6 yr.

Intervention

All patients received repeat intradetrusorial injections of BoNTA 300 units (Botox, Allergan, Irvine, CA) under cystoscopic control on an inpatient basis.

Measurements

The preliminary assessment included voiding diary, urodynamics, kidney and bladder ultrasound, and cystourethrography. Patients also completed a standardised quality-of-life (QoL) questionnaire. Clinical evaluation, urodynamics, urinary tract imaging, and QoL assessment were repeated every year throughout the follow-up.

Results and limitations

Before treatment, all patients complained of urinary incontinence and had DO. Bilateral and monolateral renal pelvis dilatation were detected in six and five patients, respectively, and a monolateral and third-grade vesicoureteral reflux was observed in three. At 6-yr follow-up, a significant decrease in the frequency of daily incontinence episodes (p < 0.01), a significant increase in first uninhibited detrusor contraction and in maximum bladder capacity (p < 0.001 for both), and a significant decrease in maximum pressure of these contractions (p < 0.01) were observed. Fifteen patients (88.2%) were completely continent. Renal pelvis dilatation and vesicoureteral reflux resolved in all cases, and the QoL index significantly increased. Limitations of the study are related to the small number of included patients.

Conclusions

In SCI patients with refractory NDO who do not want or are unfit for invasive reconstructive surgery, BoNTA intravesical treatment represents a valid alternative to control DO and urinary incontinence and to preserve upper urinary tract function over a long-term follow-up.  相似文献   
83.
There is increasing proof that organ preservation by machine perfusion is able to limit ischemia/reperfusion injury in kidney transplantation. This study was designed to compare the efficiency in hypothermic organ preservation by machine perfusion or cold storage in an animal model of kidney autotransplantation.
Twelve pigs underwent left nephrectomy after warm ischemic time; the organs were preserved in machine perfusion ( n  = 6) or cold storage ( n  = 6) and then autotransplanted with immediate contralateral nephrectomy. The following parameters were compared between the two groups of animals: hematological and urine indexes of renal function, blood/gas analysis values, histological features, tissue adenosine-5'-triphosphate (ATP) content, perforin gene expression in kidney biopsies, and organ weight changes were compared before and after preservation.
The amount of cellular ATP was significantly higher in organs preserved by machine perfusion; moreover, the study of apoptosis induction revealed an enhanced perforin expression in the kidneys, which underwent simple hypothermic preservation compared to the machine-preserved ones. Organ weight was significantly decreased after cold storage, but it remained quite stable for machine-perfused kidneys.
The present model seems to suggest that organ preservation by hypothermic machine perfusion is able to better control cellular impairment in comparison with cold storage.  相似文献   
84.
The aim of this study was to evaluate the incidence and outcome of isolated moderate renal pelvis dilatation (RPD) [anterior–posterior diameter (APD) 10–15 mm] in an unselected population of 2-month-old infants prospectively followed for up to 12–14 months of life. Isolated moderate renal pelvis dilatation was detected in 282 of the 11,801 (2.4%), infants screened; 240 infants with normal renal ultrasound were enrolled as the control group. Resolution of RPD was considered when an APD ≤ 5 mm was found on two consecutive sonograms. Urological investigations were initiated if the RPD persisted or if urinary tract infection (UTI) occurred during follow-up, and antibiotic therapy was administered only when UTI occurred. The events of interest were resolution of the RPD, presence of uropathy and UTI. At follow-up, RPD persisted only in 18 infants; of these, four infants were diagnosed with vesicoureteral reflux (grade 1–3) and 14 with ureteropelvic junction obstruction. Of the 223 infants with RPD and 230 control infants who completed follow-up, UTI occurred in 3.6 and 2.5%, respectively. The incidence rate of UTI per 1000 person-months was 5.98 episodes in the patient group and 5.22 episodes in the control group. The rate ratio was 1.146 (95% confidence interval 0.389–3.54, p = 0.8). Our data suggest that isolated moderate RPD is essentially a self-limiting condition and that antibiotic prophylaxis for the prevention of UTI should not be performed. A non-invasive ultrasound scan performed during the follow-up is sufficient to diagnose a potentially dangerous and persistent RPD.  相似文献   
85.
86.
Gene therapy for the extension of vein graft patency: a review   总被引:4,自引:0,他引:4  
The mainstay of treatment for long-segment small-vessel chronic occlusive disease not amenable to endovascular intervention remains surgical bypass grafting using autologous vein. The procedure is largely successful and the immediate operative results almost always favorable. However, the lifespan of a given vein graft is highly variable, and less than 50% will remain primarily patent after 5 years. The slow process of graft malfunction is a result of the vein's chronic maladaptive response to the systemic arterial environment, its primary component being the uncontrolled proliferation of vascular smooth muscle cells (SMCs). It has recently been suggested that this response might be attenuated through pre-implantation genetic modification of the vein, so-called gene therapy for the extension of vein graft patency. Gene therapy seems particularly well suited for the prevention or postponement of vein graft failure since: (1) the stimulation of SMC proliferation appears to largely be an early and transient process, matching the kinetics of current gene transfer technology; (2) most veins are relatively normal and free of disease at the time of bypass allowing for effective gene transfer using a variety of systems; and (3) the target tissue is directly accessible during operation because manipulation and irrigation of the vein is part of the normal workflow of the surgical procedure. This review briefly summarizes the current knowledge of the incidence and basic mechanisms of vein graft failure, the vector systems and molecular targets that have been proposed as possible pre-treatments, the results of experimental genetic modification of vein grafts, and the few available clinical studies of gene therapy for vascular proliferative disorders.  相似文献   
87.
Hair and scalp disorders in children may originate from the hair itself, scalp skin, or infectious causes and be congenital or acquired. The most common sign is alopecia, frequently brought on by tinea capitis, patchy alopecia areata, or trichotillomania. Sometimes less frequent and clinically more elusive conditions such as initial androgenetic alopecia, congenital triangular alopecia, or alopecia areata incognita may be responsible for hair loss. The noninvasive technique known as trichoscopy is being used more frequently, aiding in the prompt differential diagnosis and follow‐up of many of these diseases, oftentimes providing further examination before a treatment decision is made. This review of trichoscopy of the main scalp and hair disorders afflicting children and adolescents discusses the most important dermoscopic criteria and the usefulness of this technique.  相似文献   
88.
This statement, focused on melanonychia and nail plate dermoscopy, is intended to guide medical professionals working with melanonychia and to assist choosing appropriate management for melanonychia patients. The International Study Group on Melanonychia was founded in 2007 and currently has 30 members, including nail experts and dermatopathologists with special expertise in nails. The need for common definitions of nail plate dermoscopy was addressed during the Second Meeting of this Group held in February 2008. Prior to this meeting and to date (2010) there have been no evidence-based guidelines on the use of dermoscopy in the management of nail pigmentation.  相似文献   
89.
PURPOSE: To study child-parent similarities and the heritability of corneal shape by applying a variance component model to videokeratographic data. METHODS: Sixteen astigmatic (keratometric cylinder >/= 1.0 D) and 18 nonastigmatic (keratometric cylinder < 1.0 D) children, 7-14 years of age (mean age, 9.5 years), were enrolled with their parents. Corneal curvature, corneal astigmatism (axis and magnitude), asphericity, corneal uniformity index, and Rabinowitz McDonnell inferior-superior dioptric asymmetry value (I-S value), as well as spherical and astigmatic topographic patterns, were determined by a corneal topographer. Child-parent comparisons were assessed through a 1-way analysis of variance and the chi test. For corneal curvature, corneal astigmatism, and asphericity, heritability was estimated by a variance component model after adjustments were made for age and sex. RESULTS: Both astigmatic and nonastigmatic children showed steeper keratometric values than their parents (P < 0.05). The axis values of corneal astigmatism showed no statistically significant difference (P = 0.684) between astigmatic offspring and their parents, whereas the magnitude values were significantly higher (P < 0.001) in astigmatic children. Altogether, 68% (95% confidence interval [CI], 66%-72%) of child-parent comparisons showed the same topographic pattern between parents and their offspring. Heritability values (48%; 95% CI, 36%-57%) were statistically significant for corneal curvature (P < 0.00001) and <30% for corneal astigmatism and asphericity. CONCLUSIONS: The application of a variance component model to videokeratographic child-parent comparisons suggests that the genetic contribution to corneal shape affects corneal curvature rather than corneal astigmatism.  相似文献   
90.
Occupational skin diseases are very common among hairdressers. The aim of our study was to evaluate the frequency, the age distribution and the source of contact sensitization in a group of 209 hairdressers who consulted our Clinic from 1990 to 1999. One hundred and thirty-two patients showed one or more clinically relevant positive reactions to different allergens; 89 of them were positive to the hairdressers' series and 43 were positive to other allergens. Para-phenylenediamine base and para-toluenediamine sulphate caused the greatest number of positive reactions (77 and 29 respectively). Both glyceryl monothioglycolate and ammonium persulphate gave 25 positive patch tests. The allergens not included in the hairdressers' series which gave the greatest number of positive reactions were nickel sulphate and disperse dyes yellow 3, blue 124 and red 1. The allergens known as strong skin sensitizers have remained almost the same over the years. Preventive measures should be mandatory to protect hands and to improve the safety of this job.  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