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   1691篇
  免费   124篇
  国内免费   6篇
耳鼻咽喉   10篇
儿科学   52篇
妇产科学   54篇
基础医学   270篇
口腔科学   38篇
临床医学   175篇
内科学   338篇
皮肤病学   29篇
神经病学   122篇
特种医学   55篇
外科学   192篇
综合类   47篇
预防医学   140篇
眼科学   30篇
药学   134篇
中国医学   24篇
肿瘤学   111篇
  2023年   34篇
  2022年   87篇
  2021年   108篇
  2020年   82篇
  2019年   84篇
  2018年   97篇
  2017年   76篇
  2016年   81篇
  2015年   89篇
  2014年   98篇
  2013年   123篇
  2012年   148篇
  2011年   138篇
  2010年   78篇
  2009年   56篇
  2008年   82篇
  2007年   65篇
  2006年   54篇
  2005年   37篇
  2004年   22篇
  2003年   16篇
  2002年   19篇
  2001年   9篇
  2000年   12篇
  1999年   10篇
  1998年   3篇
  1997年   4篇
  1996年   8篇
  1993年   2篇
  1992年   4篇
  1991年   13篇
  1990年   11篇
  1989年   7篇
  1988年   6篇
  1987年   3篇
  1986年   5篇
  1984年   3篇
  1983年   4篇
  1982年   2篇
  1981年   2篇
  1980年   4篇
  1979年   2篇
  1978年   2篇
  1977年   2篇
  1973年   2篇
  1972年   2篇
  1971年   4篇
  1970年   2篇
  1969年   3篇
  1967年   7篇
排序方式: 共有1821条查询结果,搜索用时 15 毫秒
41.
While trauma registries provide the mechanisms to collect comprehensive, timely and accurate data related to the injuries and evaluate trauma care systems, they have not been established in most developing countries. On the other hand, in complex projects that have large aims, a logical framework approach (LFA) can help summarize and describe the multiple branches of the project systematically, and elucidate the main goals, extensive objectives, activities and expected outcomes. Therefore a LFA can be used to design and guide trauma registry project management, to integrate the cultural, clinical and capacity variations among countries; and to ensure early alignment of the project's design and evaluation.  相似文献   
42.
43.
44.
Journal of NeuroVirology - Multiple sclerosis (MS) is one of the common autoimmune diseases. The exact etiology of MS is still unclear, but recent studies have shown the possibility of infectious...  相似文献   
45.
There are some features for an approved soccer ball by Fédération Internationale de Football Association (FIFA), such as properties of the material, mass, pressure, stitches, etc. Many of these features up to now have been studied; nevertheless, the mechanical properties of the soccer balls to date have not been well reported. The chief purposes of the current research, hence, were to calculate the mechanical properties of the soccer balls, i.e., linear elastic, nonlinear hyperelastic, and viscoelastic, at two different sizes, including 4 and 5 which are using for football and futsal, respectively. To do this, compressive and stress-relaxation loading were applied to 38 approved soccer balls to quantify the stress–strain as well as reduced relaxation function of the balls. The strain/displacement of the balls was also measured via a high-speed camera using Digital Image Correlation (DIC) technique. The results revealed the mean elastic modulus of 66 and 67 kPa for the football and futsal balls, respectively. In addition, the maximum stresses of the football and futsal balls were 16 and 13 kPa, respectively. The nonlinear mechanical response of the soccer balls were analyzed using hyperelastic material models, i.e., Mooney-Rivlin and Ogden. A Finite Element (FE) model was also developed to verify the hyperelastic data compared to the experimental ones and, remarkably, the numerical data were in consistence with the experimental data. Finally, Prony- series was employed to quantify the viscoelastic properties of the balls. During the game, a soccer ball can reach to a speed of 210 km/h that can damage the human eye; however, the injury detail still has not been studied.  相似文献   
46.

Background:

Hypospadias is one of the most common congenital genital anomalies in males that necessitates to be operated early in infancy (when 6 to 9 months old). On the other hand, hypospadias is a challenging field of pediatric urology with multiple reconstruction techniques. A perfect hypospadias repair is supposed to return urethral continuity with sufficient caliber, eradicate phallus curvature, and supply an acceptable appearance with low complications.

Objectives:

This study aimed to evaluate the outcomes of using onlay island flap technique in the repair of hypospadias with shallow urethral plate.

Patients and Methods:

In this prospective study within June 2012 to December 2013, we performed onlay island flap procedure to repair hypospadias with shallow urethral plate measuring less than 6 millimeter. This technique was selected for all types of hypospadiasis except subcoronal type. Nesbit’s dorsal plication procedure was established for chordee. In cases with very small glans, urethroplasty was performed without glansplasty.

Results:

Twenty three patients with mean age of 30 (range 10 - 60) months underwent onlay island flap repair; all had a shallow urethral plate < 6 mm, 3 had a very small glans, and 18 had chordee. Meatus was located in distal shaft in 5 cases, mid shaft in 8, proximal in 6 and penoscrotal type in 4 patients. Chordee was corrected with Nesbit’s dorsal plication in 16 cases. Complications were: meatal stenosis in 2 cases and urethrocutaneous fistula in 2 patients, all of which were repaired surgically. Mean follow up time was 13 (3 - 20) months. All cases that had glansplasty have excellent esthetic appearance.

Conclusions:

This technique offers acceptable results regarding meatal stenosis, urethrocutaneous fistula and esthetic outcome.  相似文献   
47.
Brucellosis is associated with a high recurrence rate and requires more than one course of standard treatment; therefore, more research is required to find more effective treatments that lead to prompt recovery, and reduce the relapse of disease. This single-blind, randomized study was designed to evaluate the effect of the standard treatment for brucellosis in combination with hydroxychloroquine.A total of 177 patients with acute brucellosis were randomly assigned to one of two treatment groups: doxycycline-streptomycin (DS) and doxycycline-streptomycin-hydroxychloroquine (DSH). Clinical symptoms and signs, serological tests, and side effects of therapy were compared between the two groups during the treatment course and at three and six months after the end of drug therapy. Of the 177 patients, with a mean age of 40.5?±?16.9 years, 66.1% were males. The mean duration of clinical signs prior to admission was 43.4?±?41.1 days. Appropriate clinical responses, relapse, treatment failure, and adverse drug reactions were seen in 98.9%, 1.2%, 0.0%, and 12.6% of patients, respectively, in the DSH group vs. 86.7%, 11.6%, 2.3%, and 19.8% of patients, respectively, in the DS group. There were significant differences in clinical response and relapse rates between the two groups. The addition of hydroxychloroquine to a doxycycline-streptomycin regimen appears to increase the efficacy of treatment, accelerate improvement of clinical symptoms, and significantly reduce the rate of relapse of brucellosis.  相似文献   
48.
By going to millimeter wave (mmWave) we can use large scale MIMO due to short mmWave wavelength to overcome path loss by using beamforming to focus power of signal to the receiver. System structure of mmWave band is different with conventional MIMO because of large scale MIMO which is leading to use many RF-chains. For this reason Hybrid structure have been proposed for large Scale MIMO. By going to Hybrid structure a new issue has been created with phase shifter constraint. In this paper we propose a novel solution to make a hybrid precoding and combing to reach high spectral efficiency. Our problem includes a maximizing Frobenius norm of multiplying five complex matrices. As constraints, all elements of some matrices must have unit norm, and also the multiplication of some matrices must have a specific Frobenius norm. A novel solution is proposed for the problem, which is gained in two steps. At the first step, we propose a new decomposition usable for kind of complex matrices which could lead to reduce the dimension of the objective function, and eliminating constraints completely and in the second step, we propose an iterated algorithm for the resulting problem. By proposing another novel technique, we show that in each iteration, the optimal problem is equivalent to a quadratic optimal problem with limitations on the vector norm, and as a result, an optimal problem is obtained quickly. Moreover, some other real examples are included to demonstrate the usefulness and effectiveness of the proposed algorithm.  相似文献   
49.
Testicular torsion is a serious urological disease leading to testicular damage. This study aimed to assess the effect of minocycline on testicular ischaemia/reperfusion (I/R) injury caused by testicular torsion/detorsion. Male adult Wistar rats (n = 32) were assigned into four groups of sham, I/R, I/R + minocycline and minocycline. I/R injury was induced by two sets of surgical operations, including the rotation of the left testis (720°, counterclockwise), followed by detorsion after 4 hr. The administration of minocycline was carried out 30 min before detorsion and then continued for 8 weeks. At the end of the 8th week, rats were killed and sampling was done. Johnson's score, the height of seminiferous tubule epithelium, the mean seminiferous tubule diameter, as well as biochemical parameters, SOD, GPx and CAT, were significantly enhanced in the I/R + minocycline group compared with the I/R group. The administration of minocycline led to a marked decrease in expression levels of Caspase-3, Bax, IL-1β and TNF-α genes, and a remarkable increase in expression levels of Bcl-2, 3β-HSD and 17β-HSD3 genes compared with the I/R group. Administration of minocycline could also reduce the rate of germ cell apoptosis (TUNEL staining). Hence, minocycline was useful in the management of testicular torsion/detorsion.  相似文献   
50.
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