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   8527篇
  免费   542篇
  国内免费   17篇
耳鼻咽喉   104篇
儿科学   517篇
妇产科学   126篇
基础医学   1016篇
口腔科学   236篇
临床医学   609篇
内科学   1883篇
皮肤病学   219篇
神经病学   657篇
特种医学   177篇
外科学   1031篇
综合类   203篇
一般理论   5篇
预防医学   492篇
眼科学   248篇
药学   714篇
中国医学   64篇
肿瘤学   785篇
  2023年   34篇
  2022年   116篇
  2021年   296篇
  2020年   154篇
  2019年   208篇
  2018年   253篇
  2017年   176篇
  2016年   211篇
  2015年   214篇
  2014年   323篇
  2013年   419篇
  2012年   630篇
  2011年   600篇
  2010年   384篇
  2009年   282篇
  2008年   457篇
  2007年   445篇
  2006年   389篇
  2005年   409篇
  2004年   394篇
  2003年   335篇
  2002年   298篇
  2001年   193篇
  2000年   193篇
  1999年   179篇
  1998年   105篇
  1997年   77篇
  1996年   63篇
  1995年   67篇
  1994年   46篇
  1993年   37篇
  1992年   113篇
  1991年   99篇
  1990年   90篇
  1989年   94篇
  1988年   75篇
  1987年   68篇
  1986年   57篇
  1985年   53篇
  1984年   52篇
  1983年   49篇
  1982年   27篇
  1981年   25篇
  1979年   41篇
  1978年   28篇
  1977年   18篇
  1976年   17篇
  1974年   24篇
  1973年   23篇
  1970年   22篇
排序方式: 共有9086条查询结果,搜索用时 15 毫秒
81.
82.
The treatment of Klebsiella pneumoniae, particularly extended-spectrum β-lactamase (ESBL)-producing K. pneumoniae, is currently a great challenge. Photodynamic antimicrobial chemotherapy is a promising approach for killing antibiotic-resistant bacteria. The aim of this study was to evaluate the capacity of 5-aminolevulinic acid (5-ALA) and its derivative 5-ALA methyl ester (MAL) in the presence of white light to cause photodynamic inactivation (PDI) of K. pneumoniae planktonic and biofilm cells. In the presence of white light, 5-ALA and MAL inactivated planktonic cells in a concentration-dependent manner. Biofilms were also sensitive to 5-ALA and MAL-mediated PDI. The mechanisms by which 5-ALA and MAL caused PDI of ESBL-producing K. pneumonia were also investigated. Exposure of K. pneumonia to light in the presence of either 5-ALA or MAL induced cleavage of genomic DNA and the rapid release of intracellular biopolymers. Intensely denatured cytoplasmic contents and aggregated ribosomes were also detected by transmission electron microscopy. Scanning electron microscopy showed that PDI of biofilms caused aggregated bacteria to detach and that the bacterial cell envelope was damaged. This study provides insights into 5-ALA and MAL-mediated PDI of ESBL-producing K. pneumoniae.  相似文献   
83.
INTRODUCTIONThis study aimed to investigate the therapeutic response to injected human umbilical cord blood mesenchymal stem cells (UCBMSCs) among albino rats with streptozotocin (STZ)-induced diabetes mellitus.METHODSControl group (GI; n = 25) rats were fed with standard rat diet. Rats with STZ-induced diabetes mellitus without (GII; n = 25) and with (GIII; n = 25) differentiated human UCBMSCs implantation were the test groups. Rats were sacrificed in Week 11 following implantation. Liver biopsies were sectioned and stained in order to highlight both the presence and function of impregnated cells in the liver tissue.RESULTSHaematoxylin and eosin-stained sections in GI and GII rats showed normal liver architecture while GIII rats showed presence of cell clusters inside the liver tissue and around the central veins. Cell clusters with blue cytoplasm were present in sections in GIII rats but absent in GI and GII rats, indicating the presence of injected differentiated human UCBMSCs. The anti-human insulin immunostaining of GIII rats showed clusters of cells within the liver parenchyma and around central veins, indicating that these cells were active and secreting insulin.CONCLUSIONUCBMSCs are proficient in differentiating into insulin-producing cells in vivo under specific conditions and, when transplanted into the liver of albino rats with STZ-induced diabetes mellitus, were able to secrete insulin and partially control the status of diabetes mellitus in rats.  相似文献   
84.
Objective To estimate the heavy metal content in soil and selected medicinal plants procured from environmentally different sites of the same city. Methods Soil and plant samples of Abutilon indicum, Calotropis procera, Euphorbia hirta, Peristrophe bycaliculata, and Tinospora cordifolia were collected from 3 environmentally different sites of the city: heavy traffic area (HTA), industrial area (IA), and residential area (RA). Pb by inductively coupled plasma emission spectrometry and compared Cd, Cr, and Ni were estimated in soil and plant samples Results The level of heavy metal was higher in soil than in plant parts studied. Accumulation of heavy metals varied from plant to plant. Pb was the highest in Calotropis procera root from HTA site and the lowest in Peristrophe bycaliculata whole plant from IA site. It was also lower in residential area than in heavy traffic area. Conclusion The level of heavy metal content differed in the same medicinal plant collected from environmentally different sites of the same city. Thus, it reiterates our belief that every medicinal plant sample should be tested for contaminant load before processing it further for medication.  相似文献   
85.
Background: Laugier-Hunziker (LH) syndrome is a rare condition in which melanocyte overactivity produces lentiginous lesions of the lips and buccal mucosa. Objective: Given the paucity of reports on therapeutic options in LH syndrome, this case is herein reported to show the response to treatment with the Q-Switched Nd:YAG laser in a 32-year-old man with LH Syndrome. Methods: The Q-Switched Nd:YAG laser was used to treat the lentiginous lesions on the mucosal surface of the lower lips using a single pass at 532 nm. Results: There was complete clearance of the mucosal lentiginous lesions with a single laser session, and recurrence was not observed after 12 months. Conclusion: The Q-Switched Nd:YAG laser is an effective treatment option for cosmetic benefit in LH Syndrome.  相似文献   
86.
87.
Between January 1980 and December 1986, 2573 patients underwent simple first time coronary artery bypass grafting, of whom 73 (65 males and 8 females) aged 34-69 years (mean 51.3 yrs) had repeat bypass grafts at Wythenshawe Hospital, Manchester. Of these 73 patients, 15 had a previous myocardial infarction, 5 hyperlipidaemia, 4 systemic hypertension, and 12 had a strong family history of ischemic heart disease. There was an overall deterioration of left ventricular function at the time of reoperation. The interval between the two operations was 5-131 months (mean 34.2 mths); recurrence of angina occurred earlier (mean 18.4 mths). Vessels grafted at the first operation were LAD (59), RCA (46), circumflex (41) and diagonal (13). The corresponding data at reoperation were LAD (55), RCA (46), circumflex (28) and diagonal (10). Blocked grafts were seen in 67 patients and new lesions noticed in 29. Reoperation was done using saphenous vein (129), internal mammary artery (5), arm veins (2) and tubular Gortex grafts (2). One patient had concurrent excision of a left ventricular aneurysm. Coronary anastomoses were performed with elective ventricular fibrillation (47) or cardioplegic arrest (91). Aortic cross clamp time varied from 0-92 minutes. Seven patients required intra-aortic balloon support. These patients died in the first 30 days, an operative mortality rate of 4.1%, and two 18 months after surgery. Sixty-eight percent of patients seen at 1 year were totally symptom free. We conclude that reoperation for coronary artery disease can be done with a low mortality and good immediate relief of symptoms.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   
88.
BACKGROUND: In this study, the efficacy of oral aspirin vs. topical aspirin in moisturizer (Vaseline Intensive Care Lotion) was studied in an open, randomized, parallel trial in patients with acute herpetic neuralgia. METHODS: Thirty patients were evaluated in the trial, with 15 in each group. The patients were randomized to receive either oral aspirin, 375-750 mg three times a day, or 75 mg topical aspirin/mL of moisturizer (5-10 mL, depending on the extent of involvement), three times a day, for 21 days. Pain was assessed daily by means of a self-rating visual analog scale and physician assessment. In addition, the skin and plasma levels of aspirin were measured in both groups. RESULTS: The mean time to onset of pain relief was 44 min with topical aspirin and 110 min with oral aspirin. The mean duration of pain relief after a single application of topical aspirin was 5.4 h, whereas it was 3.5 h with oral aspirin. The mean visual analog scale scores for pain with oral aspirin decreased from 68.2 +/- 6.1 on day zero to 43.1 +/- 8.7 on day 21, which was not significant compared with the baseline score. With topical aspirin, the baseline pain score was 77.5 +/- 3.7 and decreased to 6.8 +/- 3 on day 21 (P < 0.001 compared to the baseline score and compared to oral aspirin). The mean plasma and skin levels of aspirin following oral administration were 16.21 +/- 1.1 microg/mL and 1.97 +/- 0.3 microg/mm2, respectively. After topical administration, the mean plasma level of aspirin was 2.29 +/- 0.5 microg/mL (P < 0.01 vs. oral aspirin) and the skin level was 5.96 +/- 0.4 microg/mm2 (P < 0.05 vs. oral aspirin). Treatment tolerance was excellent in both groups. CONCLUSIONS: This trial has demonstrated that topical aspirin in moisturizer is clearly superior to oral aspirin in relieving the pain of acute herpetic neuralgia, and that the analgesic activity of aspirin is largely due to its local effect.  相似文献   
89.

Background

Transplantation of hearts retrieved from donation after circulatory death (DCD) donors is an evolving clinical practice.

Objectives

The purpose of this study is to provide an update on the authors’ Australian clinical program and discuss lessons learned since performing the world’s first series of distantly procured DCD heart transplants.

Methods

The authors report their experience of 23 DCD heart transplants from 45 DCD donor referrals since 2014. Donor details were collected using electronic donor records (Donate Life, Australia) and all recipient details were collected from clinical notes and electronic databases at St. Vincent’s Hospital.

Results

Hearts were retrieved from 33 of 45 DCD donors. A total of 12 donors did not progress to circulatory arrest within the pre-specified timeframe. Eight hearts failed to meet viability criteria during normothermic machine perfusion, and 2 hearts were declined due to machine malfunction. A total of 23 hearts were transplanted between July 2014 and April 2018. All recipients had successful implantation, with mechanical circulatory support utilized in 9 cases. One case requiring extracorporeal membrane oxygenation subsequently died on the sixth post-operative day, representing a mortality of 4.4% over 4 years with a total follow-up period of 15,500 days for the entire cohort. All surviving recipients had normal cardiac function on echocardiogram and no evidence of acute rejection on discharge. All surviving patients remain in New York Heart Association functional class I with normal biventricular function.

Conclusions

DCD heart transplant outcomes are excellent. Despite a higher requirement for mechanical circulatory support for delayed graft function, primarily in recipients with ventricular assist device support, overall survival and rejection episodes are comparable to outcomes from contemporary brain-dead donors.  相似文献   
90.
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