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   5595篇
  免费   334篇
  国内免费   37篇
耳鼻咽喉   65篇
儿科学   127篇
妇产科学   280篇
基础医学   655篇
口腔科学   142篇
临床医学   434篇
内科学   1194篇
皮肤病学   68篇
神经病学   319篇
特种医学   203篇
外国民族医学   4篇
外科学   980篇
综合类   99篇
一般理论   3篇
预防医学   366篇
眼科学   275篇
药学   378篇
中国医学   11篇
肿瘤学   363篇
  2023年   41篇
  2022年   101篇
  2021年   251篇
  2020年   135篇
  2019年   192篇
  2018年   262篇
  2017年   193篇
  2016年   166篇
  2015年   165篇
  2014年   259篇
  2013年   306篇
  2012年   414篇
  2011年   439篇
  2010年   259篇
  2009年   201篇
  2008年   301篇
  2007年   293篇
  2006年   250篇
  2005年   255篇
  2004年   211篇
  2003年   209篇
  2002年   180篇
  2001年   75篇
  2000年   75篇
  1999年   57篇
  1998年   27篇
  1997年   22篇
  1996年   33篇
  1995年   28篇
  1994年   19篇
  1993年   17篇
  1992年   58篇
  1991年   53篇
  1990年   51篇
  1989年   49篇
  1988年   29篇
  1987年   29篇
  1986年   34篇
  1985年   30篇
  1984年   24篇
  1983年   16篇
  1982年   14篇
  1981年   9篇
  1979年   21篇
  1978年   11篇
  1976年   10篇
  1974年   10篇
  1973年   11篇
  1971年   10篇
  1970年   9篇
排序方式: 共有5966条查询结果,搜索用时 15 毫秒
1.
Transfusion transmissible infections (TTIs) have been a public health challenge for the accessibility, quality and safety of blood transfusion. The present study aimed to consider the prevalence and the trends of hepatitis B virus (HBV), hepatitis C virus (HCV), Human T-cell leukemia virus type 1 (HTLV-1), human immunodeficiency virus (HIV) and syphilis across the ten years among retrospective blood donors. A retrospective investigation of blood donors’ data covering the period from 22 May 2009 to 22 May 2019 was done. Data was accumulated and analyzed from Blood Transfusion Center records, pertaining to all donors who were screened for various TTIs using respective immunological techniques. Out of the 682,171 screened donors in the 2009–2019 study period, 2470 (0.36 %) were infected with at least one infectious agent. The overall prevalence of HBV, HCV, HTLV-1, HIV and syphilis were 1700 (0.25 %), 184 (0.027 %), 335 (0.05 %), 4 (0.0.05 %) and 247 (0.036 %), respectively. The study showed male dominated donor pool (96.79 %) with higher prevalence (0.34 %) of TTIs compared to female donors (0.02 %) with 3.21 % population. Despite the low prevalence of TTIs in our study, HBV, HCV, syphilis and HIV have remained a big threat to safe blood transfusion in Iran. Strict adherence to selection criteria, algorithm of donor screening, use of highly sensitive and specific methods for detection of TTIs, regular consultation and health education programs, prevention and sanitization strategies to reduce the risk of TTIs are recommended to reduce the risk of TTIs and ensure the safety of blood transfusion for recipient.  相似文献   
2.
3.
The clinical outcome and appropriate management for patients showing 'borderline changes' on allograft biopsy after renal transplantation is still controversial. In an attempt to identify predictive factors of clinical outcome of patients with such lesions, we reviewed the clinical course of 91 patients with borderline changes. Multivariate analysis revealed significant and independent effects of histological stage (i + t < or = or > 2) and time to borderline changes (< or = or > 3 months after transplant) on serum creatinine levels at 1 year from borderline changes episodes (respectively, p = 0.04 and p = 0.02) and only a significant effect of time to borderline changes on serum creatinine levels at 2 years (p = 0.005). Renal function at 1 year and 2 years as 5- and 8-year graft survival were not significantly different in the group of patients treated with antirejection therapy (T group, n = 49) compared with the untreated group (UT group, n = 42). This study strongly suggests that borderline changes with histological score (i + t) > 2 and late episodes of borderline changes should be considered to be of poor prognosis.  相似文献   
4.
Haemangiomas are the most common tumours of infancy. They typically proliferate then involute with considerable variation as regards to their rates of proliferation and involution. Haemangioma of the nasal tip is a lesion of special characteristics. During proliferation, it expands, contracts and deviates the nasal cartilages. Particularly, it regresses slowly and frequently involutes incompletely. That is why excision of the lesion is frequently suggested. The present study was conducted to evaluate open rhinoplasty after initial non-excision treatment modalities namely, intra-lesional corticosteroid injections and laser treatment, as a protocol of treatment for nasal tip haemangiomas. Twelve patients with nasal tip haemangiomas were included in the present study. Patients of both sexes, of different ages, with deep and mixed haemangiomas were studied. Disfigurement was the constant presenting symptom. Initial non-excision treatment reported different responses as denoted by the regression of the lesions’ size. Haemangiomas constantly extended between the medial crura of the alar cartilages as noted by the constant widening of the columella pre-operatively and the obvious separation of the nasal cartilages intra-operatively. This separation was constantly found to require approximation by sutures. The results of the present study concluded that whenever an early presentation with nasal tip haemangioma could be established, initial non-excision treatment followed by open rhinoplasty could be a useful protocol of treatment. Within the limitations of the present study, this protocol could achieve an early, safe and effective treatment for nasal tip haemangiomas with provisionally acceptable cosmetic outcomes so far.  相似文献   
5.
6.
Antimurine antibody formation following OKT3 therapy   总被引:1,自引:0,他引:1  
OKT3 is an IgG2a murine monoclonal antibody directed against the CD3 antigen receptor of human T lymphocytes. A major concern with OKT3 treatment in solid organ transplant recipients is the development of antimouse antibody, which may preclude retreatment with this agent. We have administered OKT3 on 215 occasions (150 renal, 34 hepatic, 26 cardiac, 5 pancreatic) in 179 patients between April 1982 and December 1988. The mean duration of treatment was 10.5 days (range, 2-22 days). Antimouse antibody data were analyzed on the most recent 133 treatment courses where the antibody status was available pretreatment. Determination of antimouse antibody production was elicited by ELISA technology at days 0, 7, 14, and 28 of OKT3 treatment. Patients were categorized according to the antibody response as follows: (a) absence of antibody; (b) low titer (1:100); or (c) high titer (greater than or equal to 1:1000). Our earlier experience has demonstrated that retreatment with OKT3 is successful in groups a and b. The development of antimurine antibodies was analyzed with regard to the following parameters: (1) The duration of OKT3 treatment; (2) treatment type (prophylactic, primary, or secondary); (3) primary treatment or retreatment; (4) concomitant immunosuppressive regimen (double or triple therapy); (5) dosage of concomitant immunosuppressive drugs; and (6) transplant organ type. The following results were obtained. (1) Duration of treatment had no effect on antibody production (11.0 days in antibody negative and 10.0 days in antibody positive). (2) There was no difference in antibody formation rates for the first treatment of OKT3 when it was used as prophylaxis (26%), primary (19%), or secondary (27%) therapy. (3) Antibody formation rate with first treatment was 29%; with retreatment, patients who were antibody negative following first treatment became positive in 28% of cases, and retreated patients who were low titer positive following first treatment converted to high titer in 57% of cases. (4) Antibody formation was higher in patients receiving double immunosuppressive therapy (36%) than in those receiving triple immunosuppressive therapy (21%) during OKT3 treatment. (5) Concomitant immunosuppression was lower in the antibody-positive group during OKT3 therapy: steroids, 61 mg/day vs. 52 mg/day; azathioprine, 89 mg/day vs. 66 mg/day; CsA, 317 mg/day vs. 186 mg/day. (6) Antibody formation rates were lower in non-renal transplants following first treatment with OKT3 (liver 17%, heart 17%, kidney 28%); this reflects the higher doses of concomitant immunosuppressive therapy used in nonrenal transplants.(ABSTRACT TRUNCATED AT 400 WORDS)  相似文献   
7.
Hepatitis C virus (HCV) infection is a major public-health-care problem, with over 170 million infected worldwide. Patients with chronic HCV infection often complain of various cognitive problems as well as symptoms of depression, anxiety, and fatigue. Relatively little is known, however, about the specific cognitive deficits that are common among HCV patients, and the influence of psychiatric symptomatology on cognitive functioning. In the current study of 21 chronically infected HCV patients, we assessed subjective cognitive dysfunction, depression, anxiety, and fatigue and compared these symptom areas to cognitive tests assessing visuoconstruction, learning, memory, visual attention, psychomotor speed, and mental flexibility. Results revealed that cognitive impairment ranged from 9% of patients on a visuoconstruction task to 38% of patients on a measure of complex attention, visual scanning and tracking, and psychomotor speed, and greater HCV disease severity as indicated by liver fibrosis was associated with greater cognitive dysfunction. Objective cognitive impairment was not related to subjective cognitive complaints or psychiatric symptomatology. These findings suggest that a significant portion of patients with chronic HCV experience cognitive difficulties that may interfere with activities of daily living and quality of life. Future research using cognitive measures with HCV-infected patients may assist researchers in identifying if there is a direct effect of HCV infection on the brain and which patients may be more likely to progress to cirrhosis and hepatic encephalopathy.  相似文献   
8.
Thirty-four patients with suspected common bile duct stones were randomized to undergo endoscopic cholangiography and stone removal prior to open cholecystectomy or to have open cholecystectomy, operative cholangiography, and common bile duct exploration. Sixteen underwent the first protocol, and 18 the second. Analysis of the ability to clear stones from the common bile duct, morbidity, mortality, hospital stay, length of operation, and hospital cost showed no difference in outcome between patients treated by either method. These data suggest there is neither an advantage nor a disadvantage to treating patients with suspected duct stones by precholecystectomy endoscopic cholangiography and stone removal.  相似文献   
9.
Cerebrospinal fluid gamma interferon (IFN-γ) and interleukin-10 levels in 39 patients with tuberculous meningitis were serially measured. Cytokine levels did not predict intracranial granuloma (IG) development, but IFN-γ levels in the top quartile after 1 month of therapy were highly associated (odds ratio = 18) with detection of an IG by computed tomography scanning.  相似文献   
10.
An anthropomorphic airway tree phantom was imaged with both hyperpolarized (HP) 3He MRI using a dynamic projection scan and computed tomography (CT). Airway diameter measurements from the HP 3He MR images obtained using a newly developed model-based algorithm were compared against their corresponding CT values quantified with a well-established method. Of the 45 airway segments that could be evaluated with CT, only 14 airway segments (31%) could be evaluated using HP 3He MRI. No airway segments smaller than approximately 4 mm in diameter and distal to the fourth generation were adequate for analysis in MRI. For the 14 airway segments measured, only two airway segments yielded a non-equivalent comparison between the two imaging modalities, while eight more had inconclusive comparison results, leaving only four airway segments (29%) that satisfied the designed equivalence criteria. Some of the potential problems in airway diameter quantification described in the formulation of the model-based algorithm were observed in this study. These results suggest that dynamic projection HP 3He MRI may have limited utility for measuring airway segment diameters, particularly those of the central airways.  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