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   1384篇
  免费   137篇
  国内免费   11篇
耳鼻咽喉   4篇
儿科学   82篇
妇产科学   9篇
基础医学   202篇
口腔科学   32篇
临床医学   135篇
内科学   247篇
皮肤病学   43篇
神经病学   190篇
特种医学   136篇
外科学   222篇
综合类   43篇
预防医学   67篇
眼科学   46篇
药学   40篇
中国医学   2篇
肿瘤学   32篇
  2022年   8篇
  2021年   15篇
  2020年   17篇
  2019年   17篇
  2018年   42篇
  2017年   19篇
  2016年   40篇
  2015年   36篇
  2014年   39篇
  2013年   55篇
  2012年   78篇
  2011年   60篇
  2010年   71篇
  2009年   74篇
  2008年   67篇
  2007年   59篇
  2006年   59篇
  2005年   52篇
  2004年   35篇
  2003年   36篇
  2002年   18篇
  2001年   25篇
  2000年   35篇
  1999年   31篇
  1998年   53篇
  1997年   49篇
  1996年   47篇
  1995年   41篇
  1994年   26篇
  1993年   31篇
  1992年   9篇
  1991年   11篇
  1990年   9篇
  1989年   24篇
  1988年   21篇
  1987年   19篇
  1986年   20篇
  1985年   16篇
  1984年   9篇
  1983年   15篇
  1982年   9篇
  1981年   15篇
  1980年   8篇
  1979年   10篇
  1978年   8篇
  1977年   14篇
  1976年   11篇
  1975年   6篇
  1972年   7篇
  1971年   12篇
排序方式: 共有1532条查询结果,搜索用时 531 毫秒
1.
Our purposes were to determine the incidence of BK viruria, viremia or nephropathy with tacrolimus (FK506) versus cyclosporine (CyA) and whether intensive monitoring and discontinuation of mycophenolate (MMF) or azathioprine (AZA), upon detection of BK viremia, could prevent BK nephropathy. We randomized 200 adult renal transplant recipients to FK506 (n = 134) or CyA (n = 66). Urine and blood were collected weekly for 16 weeks and at months 5, 6, 9 and 12 and analyzed for BK by polymerase chain reaction (PCR). By 1 year, 70 patients (35%) developed viruria and 23 (11.5%) viremia; neither were affected independently by FK506, CyA, MMF or AZA. Viruria was highest with FK506-MMF (46%) and lowest with CyA-MMF (13%), p = 0.005. Viruria >/= 9.5 log(10) copies/mL was associated with a 3-fold increased risk of viremia and a 13-fold increased risk of sustained viremia. After reduction of immunosuppression, viremia resolved in 95%, without increased acute rejection, allograft dysfunction or graft loss. No BK nephropathy was observed. Choice of calcineurin inhibitor or adjuvant immunosuppression, independently, did not affect BK viruria or viremia. Viruria was highest with FK506-MMF and lowest with CyA-MMF. Monitoring and preemptive withdrawal of immunosuppression were associated with resolution of viremia and absence of BK nephropathy without acute rejection or graft loss.  相似文献   
2.
Deceased donor factors associated with poor graft outcome are well known, but how often these factors lead to livers left untransplanted is poorly defined. A nested, case-control study was conducted using the United Network for Organ Sharing (UNOS) database from 1987 to 2005. Only those donating >/=1 solid organ were included. Primary outcome was livers not transplanted (LNT, cases) versus transplanted (LT, controls). Primary variables for multivariate analysis were donor age and obesity. Covariates included donation after cardiac death (DCD), cerebral vascular accident death, viral serologies, cancer, ALT and bilirubin. There were 23 373 (26%) LNT's from 91 362 donors who donated at least one organ. Percent LNT fell over time (1987-1990: 48%; 1991-1995: 29%; 1996-2000: 21%; 2000-2005: 16%; p < 0.01). Increased age (odds ratio: 4.2, 95% confidence interval 3.6-4.9, p < 0.01) and obesity (2.1, 1.9-2.3, p < 0.01) were significantly associated with LNT across all time periods. Other significant factors included DCD and elevated ALT. For 2001-2005, population attributable risk indicate that age >40, abnormal ALT and obesity account for 32.6%, 25.3% and 9.2% of untransplanted livers, respectively. Use of expanded criteria livers has pushed LNT lower in spite of an aging and heavier donor population. Nevertheless, age and obesity still account for a significant portion of untransplanted livers.  相似文献   
3.
4.
Wilson's disease (WD) is an inherited disorder of copper metabolism yielding marked motor deficits, including a severely disabling tremor. As a structural correlate of the disease, a variety of cerebral abnormalities has been revealed. However, the relationship between motor deficits and cerebral lesions has remained largely unknown. Here, we investigated correlation between WD tremor and cerebral magnetic resonance imaging (MRI) findings. Cerebral MRI abnormalities in 6 symptomatic WD patients were compared to findings in 6 asymptomatic WD patients and 10 healthy controls. All patients were treated with long-term copper chelating therapy. Motor symptoms including tremor were determined by Unified Parkinson's Disease Rating Scale Part III (UPDRS-III). MRI findings in symptomatic WD patients revealed significant symmetric T2*-weighted hypointense signal alterations of globus pallidus, head of the caudate nucleus, and substantia nigra. In contrast, MRI of asymptomatic WD patients did not differ from healthy controls. Correlation analysis revealed a significant positive correlation between MRI basal ganglia lesions and UPDRS action tremor score. Our results demonstrate for the first time that Wilson's disease tremor is associated with lesions of the globus pallidus, the head of the caudate nucleus, and the substantia nigra.  相似文献   
5.
INTRODUCTION: Intrathecally delivered baclofen has been used as a treatment for severe spasticity since 1984. After a successful intrathecal baclofen trial, a programmable drug delivery system was implanted. Few early complications such as infection or hematoma are observed after this surgery. OBJECTIVE: To describe an unusual and unknown complication of intrathecal baclofen therapy. METHOD: We report 2 cases of complications of intrathecal baclofen therapy, radiculalgy, that appeared early after pump implantation. The clinical symptoms and computed tomography (CT) results are described. RESULTS: The first patient described pain, which evoked left S1 radiculopathic features. The second had left L5 radiculopathic involvement. The mean pain level was estimated on a 10-point visual analog scale as 7.5 (range 4-9). Lumbar CT scan showed a conflict between the symptomatic root and the catheter and eliminated other causes of the symptoms. Treatment with analgesic drugs was successful in 1 patient. The other presented with proximal disconnection of the catheter, which led to surgical replacement of the catheter. The pain disappeared after this surgery. CONCLUSION: Intrathecal baclofen therapy with a subcutaneously implanted progammable pump can be complicated by radiculalgy secondary to a conflict between the catheter and symptomatic root. The diagnosis is made by CT lumbar scan. If medical treatment is not sufficient, surgery could be proposed to replace the catheter.  相似文献   
6.
7.
The aim of the study was to determine whether a prior diagnostic testicle biopsy can predict success or failure of testicular sperm extraction (TESE) with intracytoplasmic sperm injection (ICSI) in patients with non-obstructive azoospermia caused by testicular failure, and what is the minimum threshold of sperm production in the testis which must be surpassed for spermatozoa to reach the ejaculate. Forty- five patients with non-obstructive azoospermia caused by testicular failure underwent diagnostic testicle biopsy prior to a planned future TESE-ICSI procedure. The diagnostic testicle biopsy was analysed quantitatively, and correlated with the quantitative findings of spermatogenesis in patients with normal spermatogenesis, as well as with the results of subsequent attempts at TESE-ICSI. Men with non- obstructive azoospermia caused by germinal failure had a mean of 0-6 mature spermatids/seminiferous tubule seen on a diagnostic testicle biopsy, compared to 17-35 mature spermatids/tubule in men with normal spermatogenesis and obstructive azoospermia. These findings were the same for all types of testicular failure whether Sertoli cell only, maturation arrest, cryptorchidism, or post-chemotherapy azoospermia. Twenty-two of 26 men with mature spermatids found in the prior testis biopsy had successful retrieval of spermatozoa for ICSI, 12 of their partners became pregnant, and are either ongoing or delivered. The study suggests that 4-6 mature spermatids/tubule must be present in the testis biopsy for any spermatozoa to reach the ejaculate. More than half of azoospermic patients with germinal failure have minute foci of spermatogenesis which are insufficient to produce spermatozoa in the ejaculate. Prior diagnostic testicle biopsy analysed quantitatively (for the presence of mature spermatids) can predict subsequent success or failure with TESE-ICSI. Incomplete testicular failure may involve a sparse multi-focal distribution of spermatogenesis throughout the entire testicle, rather than a regional distribution. Therefore, it is possible that massive testicular sampling from many different regions of the testes may not be necessary for successful TESE-ICSI.   相似文献   
8.
β-Lactoglobulin was isolated from infant formulae that were ultra high temperature (UHT) -treated, sterilized or spray-dried. The effect of the isolated β-lactoglobulin on SfaII-fimbriae-mediated adhesion of Escherichia coli to human ileostomy glycoproteins was studied in vitro. β-Lactoglobulin isolated from sterilized formulae was found to perform significantly less well than preparations from spray-dried formulae (p = 0:05). Great heterogeneity was observed in the adhesion inhibitory capacity of β-lactoglobulin isolated from UHT-treated formulae. Therefore, no significant difference was observed between UHT-treated and sterilized formulae or spray-dried formulae (p < 0:10). It can be hypothesized that β-lactoglobulin from spray-dried and some UHT-treated infant formulae may affect the colonization of mucous membranes by E. coli strains causing neonatal septicaemia and meningitis.  相似文献   
9.
The anti-inflammatory, analgesic and antipyretic properties of the new non-steroidal anti-inflammatory agent, meloxicam, were investigated in a variety of animal models and compared with the properties of piroxicam, diclofenac, indomethacin and several other NSAIDs.With respect to the total effect of a single oral dose, the anti-exudative effect of meloxicam on carrageenaninduced oedema in the rat exceeded that of all the NSAIDs included in the comparison. Additionally, meloxicam showed the greatest potency of all the compounds examined with respect to adjuvant-induced arthritis in the rat, the granuloma pouch model and the cotton pellet test in the rat. Unlike indomethacin, in the carrageenan pleurisy model in the rat, meloxicam caused both a dose-dependent reduction in exudate volume and also inhibition of leucocyte migration.Meloxicam showed a strong and lasting effect on inflammatory pain in the rat. Like other NSAIDs, but unlike dipyrone, meloxicam had no effect in the hot plate and tail clamp tests, which are used to identify weak central analgesic effects. Unlike dipyrone and like indomethacin, meloxicam had no effect in a model of visceral distention pain.In common with other NSAIDs, meloxicam had no influence on the body temperature of normothermic rats in the anti-inflammatory dose range, but did reduce yeastinduced fever in the rat in a dose-dependent manner. Like piroxicam, meloxicam had a uricosuric effect on rats treated with oxonic acid.Low-dose meloxicam inhibited both bradykinin-induced and PAF-induced bronchospasm in the guinea-pig, but had no effect on acetylcholine-induced bronchospasm.Piroxicam had greater ulcerogenic effects in the rat stomach than meloxicam.The therapeutic range of meloxicam in the rat, with regard to inhibition of adjuvant arthritis, was several times greater than that of piroxicam, indomethacin, diclofenac and naproxen.  相似文献   
10.
The dominant cone-rod dystrophy gene CORD6 has previously been mapped to within an 8 cM interval on chromosome 17p12-p13. The retinal- specific guanylate cyclase gene (RETGC-1), which maps to within this genetic interval and previously was implicated in Leber's congenital amaurosis, was screened for mutations within this family and in a panel of small families and individuals with various cone and cone- rod dystrophy phenotypes. A missense mutation (E837D) was identified in affected members of the CORD6 family, as well as a second missense mutation (R838C) in three other families with dominant cone-rod dystrophy. RETGC-1 is only the fourth gene to be implicated in cone-rod dystrophy and this is the first report of dominant mutations in this gene.   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