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   1032篇
  免费   81篇
  国内免费   7篇
耳鼻咽喉   10篇
儿科学   52篇
妇产科学   13篇
基础医学   121篇
口腔科学   31篇
临床医学   97篇
内科学   304篇
皮肤病学   20篇
神经病学   54篇
特种医学   138篇
外科学   118篇
综合类   18篇
预防医学   20篇
眼科学   3篇
药学   47篇
肿瘤学   74篇
  2023年   5篇
  2022年   8篇
  2021年   17篇
  2020年   14篇
  2019年   21篇
  2018年   28篇
  2017年   16篇
  2016年   19篇
  2015年   28篇
  2014年   25篇
  2013年   47篇
  2012年   63篇
  2011年   54篇
  2010年   65篇
  2009年   46篇
  2008年   47篇
  2007年   52篇
  2006年   34篇
  2005年   36篇
  2004年   30篇
  2003年   41篇
  2002年   22篇
  2001年   23篇
  2000年   14篇
  1999年   20篇
  1998年   32篇
  1997年   40篇
  1996年   40篇
  1995年   29篇
  1994年   19篇
  1993年   18篇
  1992年   14篇
  1991年   4篇
  1990年   7篇
  1989年   14篇
  1988年   19篇
  1987年   17篇
  1986年   13篇
  1985年   13篇
  1984年   5篇
  1983年   7篇
  1982年   6篇
  1981年   12篇
  1980年   6篇
  1979年   4篇
  1977年   5篇
  1976年   6篇
  1973年   3篇
  1972年   3篇
  1967年   2篇
排序方式: 共有1120条查询结果,搜索用时 15 毫秒
11.
The incidence (%) of hyperbilirubinemia (serum bilirubin ≥257 μmol/l) was similar in neonates with a combination of ABO incompatibility and glucose-6-phosphate dehydrogenase (G-6-PD) deficiency (45%), with ABO incompatibility (54%) or G-6-PD deficiency (37%), alone (ns). Carboxyhemoglobin values, corrected for inspired CO, were similarly elevated in all three groups (0.87 ± 0.32%, 0.82 ± 0.29%, 0.76 ± 0.18%, respectively, ns), but correlated with bilirubin only in those with ABO incompatibility alone. ABO-incompatible/G-6-PD-deficient neonates, compared with those with either condition alone, are not at increased risk for hemolysis or hyperbilirubinemia.  相似文献   
12.
Twenty patients with AIDS who had intracranial lesions underwent both brain biopsy and cerebro-spinal fluid (CSF) examination to compare histological diagnosis with the polymerase chain reaction (CSF-PCR) for the identification of infectious agents. CSF-PCR was performed for herpes simplex virus, varicella zoster virus, cytomegalovirus (CMV), JC virus (JCV), Epstein-Barr virus (EBV), Toxoplasma gondii and Mycobacterium tuberculosis. A definitive diagnosis was obtained by brain biopsy in 14 patients (2 with astrocytoma, 12 with brain infection). CSF-PCR was positive for EBV DNA in 3 of 3 cases of primary cerebral lymphoma, positive for JCV DNA in 6 of 7 biopsy-proven (and one autopsy-proven) cases of progressive multifocal leukoencephalopathy (PML). CSF-PCR was positive for CMV DNA in one biopsy-proven and one autopsy-proven case of CMV encephalitis (the former also had PML) and positive for M. tuberculosis DNA in one case of tuberculous encephalitis. None of the five toxoplasmic encephalitis cases (one definite, four presumptive) were T. gondii DNA positive. There was close correlation between histology and CSF-PCR for CMV encephalitis, PML and PCL. Antitoxoplasma therapy affected the sensitivity of both histological and CSF-PCR methods. Received: 8 November 1995 Received in revised form: 9 July 1996 Accepted: 19 July 1996  相似文献   
13.
14.
A prospective study was carried out to compare the fertilizing capability and pregnancy outcome following intracytoplasmic sperm injection (ICSI) using spermatozoa obtained from ejaculates, or surgically from epididymis or seminiferous tubules. A total of 77 ICSI cycles (one per patient) was included. In all, 28 patients had severe oligoasthenoteratozoospermia, 19 patients had obstructive azoospermia and 30 patients had non-obstructive azoospermia. The main outcome measures were fertilization rate per injected metaphase II oocyte and the clinical pregnancy rate per embryo transferred back to the female recipients. In patients with severe oligoasthenoteratozoospermia, the fertilization and pregnancy rates were 79 and 25 %. In patients with obstructive azoospermia, for whom epididymal spermatozoa were used, these were 75 and 28%, and in the non-obstructive group for which testicular spermatozoa were used for injection, they were 69 and 21% respectively. These rates were not significantly different in the three groups (P = 0.85 and P = 0.14 respectively), suggesting that spermatozoa from the ejaculates and epididymal or testicular biopsies are able to fertilize equally by using ICSI. Live birth per embryo transfer was significantly reduced in patients with non-obstructive azoospermia compared to the other two groups. The high abortion rate (50%) in the group in which testicular spermatozoa were used raises doubts about the developmental competence of such embryos.   相似文献   
15.
16.
While constructing a cDNA library of human embryos, we have isolated a clone homologous to jumonji, a mouse gene required for neural tube formation. We have determined the complete coding sequence of the human homologue (JMJ) and deduced the amino acid sequence of the putative protein. We show here that human and mouse jumonji putative proteins are homologous and present 90% identity. During human embryogenesis, JMJ mRNAs are predominantly expressed in neurons and particularly in dorsal root ganglion cells. They are also expressed in neurons of human adult cerebral cortex. In view of these observations, we propose JMJ as a candidate gene for developmental defects of the central nervous system in the human. The human JMJ gene maps at position 6p24-6p23.   相似文献   
17.
18.
A pilot study was designed to examine whether the outcome of embryo transfer in women with a hydrosalpinx might be improved by surgical drainage of the hydrosalpinx at the time of oocyte collection for in- vitro fertilization treatment. A comparative, controlled but retrospective analysis of the results was performed of all women with infective tubal damage aged <40 years old, who had ovulatory cycles, a normal uterus and a partner with normal spermatozoa. A standardized treatment regimen was used. A maximum of three embryos were transferred. Hydrosalpinx was defined by prior hysterosalpingography and/or laparoscopy with transcervical dye injection. A total of 237 embryo transfer cycles in women with hydrosalpinges (tubal distension not visible in 151, visible but not drained in 30 and drained in 56) were compared with 705 embryo transfer cycles in women with tubal disease but no hydrosalpinx. Results were analysed in the first three cycles but also separately in the first cycle to check for bias. Success rates were higher in the first cycle, but did not significantly influence overall differences. Implantation rates were significantly reduced overall in the hydrosalpinx group (8.0 versus 13.2% for controls; P < 0.001), being 8.3% (P < 0.01) in the subgroup without evident tubal distension and 7.5% (not significant) in the drained hydrosalpinx group. This study shows that tubal damage with distal occlusion is associated with a marked reduction in embryo implantation, even in the absence of obvious fluid distension. Surgical drainage of distended hydrosalpinges appears to offer no benefit.   相似文献   
19.
BackgroudCurrent evidence supports the use of cemented hemiarthroplasty for treatment of intracapsular femoral neck fractures since it is associated with a lower risk of implant-related complications. However, many medical centers employ the cementless technique for the frail elderly population because it is faster and has lower cardiovascular risks and perioperative mortality. This observational study reports the outcomes of cementless bipolar hemiarthroplasty for intracapsular femoral neck fractures in patients aged 80 years and older.MethodsA total of 424 patients (female, 77.1%) with a mean age of 86.9 years were operated for intracapsular femoral neck fractures between January 2009 and December 2017. Of those, 66.7% had an American Society of Anaesthesiologists (ASA) score of 3 or more. All operations were performed with the posterolateral surgical approach and all patients received a cementless stem. Intraoperative and perioperative values and in-hospital outcomes were evaluated, and clinical and radiographical follow-up was done at 40 days, 90 days, and when possible between 5 months and 12 months postoperatively. Multivariate analysis was performed to evaluate if there were factors affecting mortality.ResultsThe mean operative time was 50 minutes. There were no deaths intraoperatively. Intraoperative periprosthetic fractures occurred in 2.1% of the cases with 66.7% of them fixed through cerclage wires intraoperatively. The median length of hospitalization was 11 days (interquartile range, 8.75–15) and 2.4% of patients died while in hospital after surgery. Approximately 91.5% of patients presented with perioperative anemia. Only 1.9% of the complications were related to the implant, 62.5% of which were dislocations. More than 90% of patients were ambulatory either autonomously or with support at each follow-up assessment. Age, male sex, and higher ASA score were related to increased mortality.ConclusionsDespite some limitations, this observational study underlines that a cementless femoral stem of modern design can give good clinical outcomes, thus being an appropriate solution especially for the frail elderly.  相似文献   
20.
This paper describes the general design and main results of the Italian proficiency testing program for the analysis of psychoactive substances in urine, a long-term initiative created in 1995 on an educational basis and characterized by an innovative internet-based service for data exchange between laboratories and the organizing body. Batches of six urine samples, validated by reference laboratories, are sent every 3 months to participating laboratories, which may choose which classes of substances to test from those planned by the program panel and, within those classes, which type of analytical commitment to work on: identification of just one class (Option 1), identification of single substances (Option 2), or identification and quantification of single substances (Option 3). Comprehensive periodical reports and annual reports are provided to participants with evaluation of their performance and an annual workshop is organized to discuss technical-scientific topics related to clinical, forensic and analytical toxicology. About 200 laboratories currently participate in the program and a total of 67,059 analyses have been carried out since 1995. The mean percentage of correct results was 96.8%, with a yearly improvement of about 0.4%. The best average false positive and false negative rates were obtained for methadone (0.2% and 2.1% respectively) and cocaine (0.3% and 2.2%). The worst average false positive rates were obtained for amphetamines and opiates (3.2% and 5.0%) and worst average false negative rates for amphetamines, barbiturates and cannabinoids (17.4%, 30.7% and 19.9%). Received: 29 June 1998 / Received in revised form: 23 February 1999  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