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   5482篇
  免费   194篇
  国内免费   42篇
耳鼻咽喉   155篇
儿科学   182篇
妇产科学   295篇
基础医学   326篇
口腔科学   355篇
临床医学   426篇
内科学   1330篇
皮肤病学   59篇
神经病学   371篇
特种医学   235篇
外科学   1176篇
综合类   68篇
预防医学   103篇
眼科学   222篇
药学   164篇
中国医学   4篇
肿瘤学   247篇
  2024年   3篇
  2023年   32篇
  2022年   43篇
  2021年   127篇
  2020年   82篇
  2019年   90篇
  2018年   113篇
  2017年   114篇
  2016年   184篇
  2015年   212篇
  2014年   246篇
  2013年   316篇
  2012年   430篇
  2011年   412篇
  2010年   252篇
  2009年   213篇
  2008年   383篇
  2007年   483篇
  2006年   438篇
  2005年   439篇
  2004年   391篇
  2003年   255篇
  2002年   283篇
  2001年   38篇
  2000年   11篇
  1999年   11篇
  1998年   16篇
  1997年   15篇
  1996年   14篇
  1995年   10篇
  1994年   10篇
  1993年   6篇
  1992年   6篇
  1991年   9篇
  1989年   4篇
  1988年   1篇
  1987年   6篇
  1985年   5篇
  1984年   3篇
  1983年   2篇
  1981年   1篇
  1980年   1篇
  1977年   1篇
  1976年   1篇
  1975年   1篇
  1973年   2篇
  1972年   1篇
  1971年   1篇
  1963年   1篇
排序方式: 共有5718条查询结果,搜索用时 890 毫秒
961.
962.
Research questionDoes preimplantation genetic testing for aneuploidy (PGT-A) influence the discontinuation rate in women with advanced maternal age (AMA) undergoing IVF?DesignRetrospective longitudinal cohort study carried out at a single IVF clinic in Turkey. In total, 401 consecutive AMA cases were included. Discontinuation rates of pre-intervention (conventional IVF; June 2013 to October 2014; 203 couples; 270 cycles) and post-intervention (PGT-A; April 2015 to June 2016; 198 couples; 285 cycles) periods were compared. To delineate the reason for discontinuation, a telephone survey was conducted. Primary outcome measure was cumulative discontinuation rate before completing three cycles of IVF treatment without achieving an ongoing pregnancy.ResultsThe discontinuation rates after the first and second failed cycles were comparable between the two arms as were the cumulative discontinuation rates before completing three cycles. The cumulative ongoing pregnancy rate per embryo transfer was significantly higher in the PGT-A arm (43.2% versus 16.8%; P < 0.001). The cumulative ongoing pregnancy rate per patient was comparable between the two arms (20.7% versus 16.3%, respectively). Female age was the only significant contributor to treatment discontinuation (hazard ratio [HR] 1.07; 95% CI 1.09 to 1.13). Of the 296 couples discontinuing treatment in both arms, 179 (179/296 [60.5%]) participated in the survey; overall, psychological burden was the main reason for treatment discontinuation (37/179 [20.7%]).ConclusionsAbout 90% of AMA cases not achieving an ongoing pregnancy discontinue IVF treatment before completing three cycles. Discontinuation rate is not reduced by carrying out PGT-A. Female ageing is the only significant contributor, with a hazard of discontinuing further IVF treatment of 7% with female ageing of 1-year.  相似文献   
963.
Studies on the frequency of burned limbs according to season and months are limited. The burning of some body limbs, especially in some months, shows that the causes of burns are different, and knowing the reasons is important for providing preventive measures. The aims of this study were to determine the distribution rate of child burns by months and seasons and to contribute to preventive measures by determining the distribution of the burning of body limbs by months. We retrospectively evaluated 419 paediatric patients (0‐17 years of age) who were hospitalised in the burn unit between 1 May 2017 and 1 November 2018. The demographic characteristics of the patients were recorded according to age, gender, months, and seasons of the patients admitted; cause of burns; degree of burns; total body surface area; and burning regions. The distribution of burns by months was established as being mainly in May to October. As for the distribution of the patients according to the seasons, it was found that it was most common in summer, 122 (29.1%), and in the autumn season as well, it was 122 (29.1%). While body burns increased in the summer‐autumn seasons (P < .023), genital area burns were the lowest in winter and were the highest in summer and autumn seasons. Genital site burns increased statistically in September, October, and November (P < .010). Burn traumas are observed to be more frequent in some seasons and months. The environments where individuals live, forms of life, forms of warming, areas of interest, and sociocultural and economic levels are the causes of this variability.  相似文献   
964.
Experimental and clinical data strongly suggests that nitric oxide (NO) plays a pivotal role in migraine. This is also supported by studies of migraine induced by substances that release NO. NO is synthesized from L-arginine by endothelial NO synthase (NOS). Asymmetric dimethylarginine (ADMA) is the major endogenous competitive inhibitor of NOS. Symmetric dimethylarginine (SDMA) is an inactive stereoisomer of ADMA. It may reduce NO production by competing with arginine for cellular uptake. The aim of this study was to measure the levels of ADMA, SDMA and L-arginine in migraine patients during the interictal period. One hundred migraine patients and 100 healthy volunteers were recruited. The patients were in the interictal period and classified into two groups as having migraine with aura and migraine without aura. Their serum ADMA, SDMA and L-arginine levels were measured by high-performance liquid chromotography (HPLC) method. ADMA, SDMA and L-arginine levels were significantly higher in migraine patients compared to the control group. But there was no difference between the patients with and without aura. These results suggest that NOS inhibitors and L-arginine/NO pathway plays an important role in migraine pathopysiology.  相似文献   
965.
Colorectal cancer (CRC) ranked third in cancer related death and its incidence has been increasing worldwide. In recent decades important therapeutic advances have been developed in treatment of metastatic CRC (mCRC), such as monoclonal antibodies against epidermal growth factor receptor (anti-EGFR), which provided additional clinical benefits in mCRC. However, anti-EGFR therapies have limited usage due to approximately 95% of patients with KRAS mutated mCRC do not response to anti-EGFR treatment. Thus, KRAS mutation is predictive of nonresponse to anti-EGFR therapies but it alone is not a sufficient basis to decide who should not be received such therapies because; approximately fifty percent (40%-60%) of CRC patients with wild-type KRAS mutation also have poor response to anti-EGFR based treatment. This fact leads us to suspect that there must be other molecular determinants of response to anti-EGFR therapies which have not been identified yet. Current article summarizes the clinical efficacy of anti-EGFR therapies and also evaluates its resistance mechanisms.  相似文献   
966.
967.
Objective:  The aim of the study was to evaluate the influence of dental and periodontal treatments to the course of oral ulcers in patients with Behcet's disease (BD).
Methods:  Fifty-eight consecutive BD patients with oral ulcers were studied. Twenty-nine patients were in the intervention group (F/M: 15/14, mean age: 39.6 ± 6.9 years) and 29 (F/M: 15/14, 39.4 ± 10.6 years) were followed with a conventional treatment approach. In addition to oral hygiene education, dental and periodontal treatments were carried out in the intervention group, whereas the control group was only given oral hygiene education. Patients were evaluated in the pre-treatment observation period (1 month), treatment period (1 month) and 6 months after treatment.
Results:  An increase in the number of new oral ulcers (4.1 ± 3.5) was observed within 2 days during the treatment compared with 3–30 days during treatment month (2.3 ± 1.2) ( P  = 0.002). However, 6 months after the treatment, the number of oral ulcers (1.9 ± 1.5) was significantly lower compared with the pre-treatment observation (4.8 ± 3.2) ( P  = 0.000) and treatment periods (6.4 ± 2.3) in the intervention group ( P  = 0.05), whereas a similar oral ulcer presence was observed in the control group (2.8 ± 2.4, 3.7 ± 2.3 and 4.8 ± 4.3, respectively) ( P  > 0.05). Dental and periodontal indices were also better in the intervention group during the 6-month follow-up.
Conclusion:  Our results suggest that, in BD patients, dental and periodontal therapies could be associated with a flare-up of oral ulcers in the short term, but may decrease their number in longer follow-up. They also lead to a better oral health.  相似文献   
968.
969.

Introduction

The aim of this in vitro study was to evaluate the fracture type and test the effects of 2 different fibers on fracture strength of roots with reattached fragments. The null hypothesis was that adding suitable fibers to the content of dual-cure adhesive resin cement increases the fracture resistance of reattached fragments under vertical forces.

Methods

Root canals of 45 teeth were prepared, and the teeth were intentionally fractured into 2 separate fragments. Control groups (n = 7 each) consisted of unfractured teeth with instrumented and obturated or only instrumented root canals. The fractured teeth were divided into 3 groups (n = 15 each), and separated fragments were reattached by using (1) dual-cured resin cement (Clearfil SA), (2) dual-cured resin cement + polyethylene fiber (Construct), or (3) dual-cured resin cement + glass fiber (Stick-Net). Force was applied at a constant speed of 0.5 mm/min to the root until fracture. Mean load was recorded and analyzed statistically by using Kruskal-Wallis and Dunn tests (P = .05). Fracture types were analyzed by using χ2 analysis with Yates correction.

Results

Stick-Net demonstrated the lowest fracture resistance (P < .05), whereas Construct and Clearfil SA had similar fracture strengths (P > .05). The roots in the control group showed the highest fracture resistance. However, there was no statistically significant difference between the Construct, Clearfil SA, and control groups (P > .05).

Conclusions

Separated fragments of vertically fractured teeth can be reattached by using a dual-cured resin or by adding polyethylene fiber (Construct).  相似文献   
970.
Rhabdomyosarcoma is a malignant tumor that is most often seen in children younger than 15 years of age. This pathology is found mainly in the head and neck region. Treatment of rhabdomyosarcoma at early stages of life usually affects the dental and osseous development of children. Because of impaired development, microstomia can arise, making dental treatment more difficult. This article presents a patient with microstomia caused by resection of an embryonal rhabdomyosarcoma in the nasolabial region. The patient was treated with 5 dental implants and fixed hybrid prosthesis in the maxilla and 2 implants supporting an overdenture in the mandible.  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