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   5730篇
  免费   403篇
  国内免费   35篇
耳鼻咽喉   143篇
儿科学   152篇
妇产科学   138篇
基础医学   854篇
口腔科学   176篇
临床医学   537篇
内科学   1166篇
皮肤病学   63篇
神经病学   331篇
特种医学   164篇
外国民族医学   3篇
外科学   914篇
综合类   115篇
一般理论   4篇
预防医学   344篇
眼科学   145篇
药学   470篇
中国医学   74篇
肿瘤学   375篇
  2024年   6篇
  2023年   60篇
  2022年   160篇
  2021年   257篇
  2020年   161篇
  2019年   223篇
  2018年   298篇
  2017年   174篇
  2016年   219篇
  2015年   214篇
  2014年   293篇
  2013年   342篇
  2012年   576篇
  2011年   536篇
  2010年   277篇
  2009年   223篇
  2008年   315篇
  2007年   296篇
  2006年   262篇
  2005年   221篇
  2004年   186篇
  2003年   177篇
  2002年   157篇
  2001年   55篇
  2000年   60篇
  1999年   51篇
  1998年   39篇
  1997年   25篇
  1996年   20篇
  1995年   12篇
  1994年   20篇
  1993年   15篇
  1992年   23篇
  1991年   22篇
  1990年   16篇
  1989年   16篇
  1988年   20篇
  1987年   20篇
  1986年   8篇
  1985年   13篇
  1984年   7篇
  1983年   4篇
  1980年   6篇
  1979年   6篇
  1978年   6篇
  1977年   6篇
  1975年   5篇
  1974年   12篇
  1973年   11篇
  1971年   4篇
排序方式: 共有6168条查询结果,搜索用时 49 毫秒
71.
Renal cell carcinoma (RCC) is the most common renal malignancy in adults and exhibits highly intrinsic and acquired resistance to standard therapeutic strategies. We sought to determine the anti-cancer activity of hydroalcoholic extract of Nigella sativa seeds (NSE) and thymoquinone (TQ). Human renal cell carcinoma (ACHN) and fibroblast L929 cell lines were treated with NSE and TQ, and cytotoxicity was measured using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium (MTT) assay. Cell death pattern was determined by annexin V and propidium iodine (PI)-staining methods. Exposure to NSE, TQ and cisplatin significantly inhibited the growth of ACHN cells and showed significant increase of early apoptotic cells. Normal cells were more resistant to NSE and TQ-induced effects. The present study demonstrates that N. sativa and TQ exert anti-proliferative and pro-apoptotic effects on ACHN cells in a concentration and time-dependent manner, which suggests their potential to be used as a new therapeutic strategy for renal cancers.  相似文献   
72.
Ewing's sarcoma is an aggressive malignancy of bone and soft tissue with high incidence of metastasis and resistance to chemotherapy. Cytochrome P450 (CYP) monooxygenases are a family of enzymes that are involved in the metabolism of exogenous and endogenous compounds, including anti‐cancer drugs, and have been implicated in the aggressive behaviour of various malignancies. Tumour samples and clinical information including age, sex, tumour site, tumour size, clinical stage and survival were collected from 36 adult and paediatric patients with Ewing's sarcoma family tumours. Tissue microarrays slides were processed for immunohistochemical labelling for CYP3A4, CYP3A5 and CYP3A7 using liver sections as positive control. The intensity of staining was scored as negative, low or high expression and was analysed statistically for any association with patients' clinical information. Four cases were later excluded due to inadequate viable tissue. CYP3A4 staining was present in 26 (81%) cases with high expression noted in 13 (40%) of 32 cases. High expression was significantly associated with distant metastases (P < 0.05). CYP3A5 and CYP3A7 were expressed in 5 and 13 cases respectively (15.6%, 40.6%). There was no association between the expression of CYP3A isoforms and age, sex, tumour size, or location (pelvic or extra‐pelvic). None of the biomarkers showed any correlation with overall or disease‐free survival. In conclusion, expression of CYP3A isoforms is noted in Ewing's sarcoma tumours and high CYP3A4 expression may be associated with metastasis. Additional studies are needed to further investigate the role of CYP3A4 in the prognosis of these tumours.  相似文献   
73.

Introduction:

Truncus arteriosus with intact ventricular septum is a rare and unique variant of persistent truncus arteriosus (PTA) which usually presents with central cyanosis and congestive heart failure in neonate and early infancy. Associated cardiac and non-cardiac anomalies may affect morbidity and mortality of these patients.

Case Presentation:

We describe clinical presentation, echocardiography and angiographic features of a 7-month old boy with PTA and intact ventricular septum who underwent surgical repair of the anomaly at our institution. Operative findings, surgical procedure and short-term outcome are reported.

Conclusions:

While our patient had systemic pulmonary arterial pressure at the time of complete surgical repair, it was improved after surgery.  相似文献   
74.
In this research, tannin (TA) extracted from Acacia mangium and a cationic surfactant, cetyltrimethylammonium bromide (CTAB), were used to modify and enhance the physical and electrochemical properties of a polypyrrole (PPy) composite. Brunauer–Emmett–Teller (BET) analysis presented a higher degree of surface area and porosity for the PPy/TA/CTAB nanocomposite. A highly porous and rod like structure with a lumpy surface was observed for PPy/TA prepared in the presence of CTAB by Field Emission Scanning Electron Microscopy (FESEM) and Transmission Electron Microscopy (TEM). Cyclic voltammograms of the modified SPE electrode using PPy/TA/CTAB displayed an enhanced current response compared to the electrode modified with only PPy or PPy/TA. Electrochemical Impedance Spectroscopy (EIS) exhibited a lower value of charge transfer resistance (Rct) and higher electron transfer for the modified electrode, making the nanocomposite a promising candidate for biosensor application.

Tannin (TA) extracted from Acacia mangium and a cationic surfactant, cetyltrimethylammonium bromide (CTAB), were used to modify and enhance the physical and electrochemical properties of polypyrrole (PPy) composite.  相似文献   
75.

Purpose

To assess a virtual pointer in supporting surgical trainees’ development of professional vision in laparoscopic surgery.

Methods

We developed a virtual pointing and telestration system utilizing the Microsoft Kinect movement sensor as an overlay for any imagine system. Training with the application was compared to a standard condition, i.e., verbal instruction with un-mediated gestures, in a laparoscopic training environment. Seven trainees performed four simulated laparoscopic tasks guided by an experienced surgeon as the trainer. Trainee performance was subjectively assessed by the trainee and trainer, and objectively measured by number of errors, time to task completion, and economy of movement.

Results

No significant differences in errors and time to task completion were obtained between virtual pointer and standard conditions. Economy of movement in the non-dominant hand was significantly improved when using virtual pointer (\(p = 0.012\)). The trainers perceived a significant improvement in trainee performance in virtual pointer condition (\(p < 0.001\)), while the trainees perceived no difference. The trainers’ perception of economy of movement was similar between the two conditions in the initial three runs and became significantly improved in virtual pointer condition in the fourth run (\(p = 0.017\)).

Conclusions

Results show that the virtual pointer system improves the trainer’s perception of trainee’s performance and this is reflected in the objective performance measures in the third and fourth training runs. The benefit of a virtual pointing and telestration system may be perceived by the trainers early on in training, but this is not evident in objective trainee performance until further mastery has been attained. In addition, the performance improvement of economy of motion specifically shows that the virtual pointer improves the adoption of professional vision— improved ability to see and use laparoscopic video results in more direct instrument movement.
  相似文献   
76.
Purpose: To investigate the psychometric properties of the Persian version of Caregiver Burden Scale (CBS) in caregivers of patients with spinal cord injury.

Methods: This is a cross-sectional study. After a forward–backward translation, the CBS was administered to 110 caregivers of patients with spinal cord injury (men?=?60, women?=?50). Factor structure was evaluated by confirmatory factor analysis. The Internal consistency and test–retest reliability of the CBS were examined using Cronbach’s α and the intraclass correlation coefficient, respectively. Construct validity was assessed by examining the relationship among CBS and the World Health Organization Quality of Life, and the Beck Depression Inventory.

Results: The results of confirmatory factor analysis provided support for a five-factor model of CBS. All subscales of CBS revealed acceptable internal consistency (0.698–0.755), except for environment subscale (0.559). The CBS showed adequate test–retest reliability for its subscales (0.745–0.900). All subscales of CBS significantly correlated with both Beck Depression Inventory and World Health Organization Quality of Life, confirming construct validity.

Conclusions: The Persian version of the CBS is a valid and reliable measure for assessing burden of care in caregivers of patients with spinal cord injury.
  • Implications for Rehabilitation
  • Spinal cord injury leads to depression, high levels of stress and diminished quality of life due to the high physical, emotional, and social burdens in caregivers.

  • Persian version of the Caregiver Burden Scale is a valid and reliable tool for assessing burden in Iranian caregivers of patients with spinal cord injury.

  相似文献   
77.

Purpose

To evaluate the short-term results of sub-tenon’s injection of bevacizumab in patients with clinically significant macular edema (CSME).

Methods

In this prospective non-comparative interventional case series, sub-tenon’s injection of 2.5 mg/0.1 ml bevacizumab was performed for eyes with CSME. Macular thickness and best corrected visual acuity measurements were performed before and one month after injections.

Results

Nineteen eyes of twelve patients with a mean age of 59.8 ± 5.7 years were evaluated. Thirteen eyes (68.4%) had center-involving macular edema. No significant difference was observed between pre- and post-injection central subfield retinal thickness measurements (P = 0.3). Central subfield thickness measurements improved or remained unchanged in 13 eyes (68.4%). Baseline BCVA of 0.48 ± 0.35 LogMAR improved to 0.36 ± 0.26 LogMAR after injection (P = 0.01). Improvement of >2 lines in BCVA was found in 5 eyes (26.3%), and no eye lost >2 lines of BCVA. No complication associated with sub-tenon’s injection was observed.

Conclusion

Sub-tenon’s injection of bevacizumab resulted in significant short-term visual improvement in eyes with CSME. Retinal thickness changes were not significant.  相似文献   
78.
79.
80.
AIDS and Behavior - Injection drug use has been the leading route of HIV transmission in Iran. We assessed HIV prevalence, risk behaviors, and uptake of prevention services among people who inject...  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