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   20394篇
  免费   1532篇
  国内免费   54篇
耳鼻咽喉   238篇
儿科学   686篇
妇产科学   390篇
基础医学   3121篇
口腔科学   325篇
临床医学   2073篇
内科学   4525篇
皮肤病学   283篇
神经病学   2292篇
特种医学   728篇
外国民族医学   3篇
外科学   2652篇
综合类   207篇
一般理论   7篇
预防医学   1233篇
眼科学   693篇
药学   996篇
中国医学   14篇
肿瘤学   1514篇
  2021年   254篇
  2020年   173篇
  2019年   284篇
  2018年   349篇
  2017年   271篇
  2016年   354篇
  2015年   352篇
  2014年   439篇
  2013年   637篇
  2012年   991篇
  2011年   1059篇
  2010年   623篇
  2009年   561篇
  2008年   870篇
  2007年   1026篇
  2006年   969篇
  2005年   923篇
  2004年   928篇
  2003年   812篇
  2002年   822篇
  2001年   635篇
  2000年   615篇
  1999年   499篇
  1998年   210篇
  1997年   190篇
  1996年   153篇
  1995年   174篇
  1994年   146篇
  1993年   148篇
  1992年   438篇
  1991年   411篇
  1990年   406篇
  1989年   363篇
  1988年   350篇
  1987年   339篇
  1986年   352篇
  1985年   312篇
  1984年   267篇
  1983年   229篇
  1982年   164篇
  1981年   162篇
  1980年   136篇
  1979年   222篇
  1978年   201篇
  1977年   139篇
  1976年   142篇
  1975年   140篇
  1974年   171篇
  1973年   163篇
  1972年   133篇
排序方式: 共有10000条查询结果,搜索用时 343 毫秒
941.
Kaplan M  Hammerman C  Renbaum P  Klein G  Levy-Lahad E 《Lancet》2000,356(9230):652-653
We asked whether UDP glucuronosyltransferase (UGT) gene promoter polymorphism (Gilbert's syndrome) would increase hyperbilirubinaemia in direct Coombs' negative ABO-incompatible neonates, as seen in other combinations with this condition. 40 ABO-incompatible and 344 ABO-compatible controls had an allele frequency of 0.35 for the variant promoter gene. The incidence of hyperbilirubinaemia was significantly higher only in the former who were also homozygotes for the variant UGT promoter, compared with ABO-incompatible babies homozygous for the normal UGT promoter (43% vs 0, p=0.02), and with ABO-compatible controls of all UGT genotypes combined (relative risk 5.65, 95% CI 2.23-14.31). Gilbert's syndrome is a determining factor for neonatal hyperbilirubinaemia ABO incompatibility.  相似文献   
942.
943.
For individuals meeting Bethesda criteria for hereditary nonpolyposis colorectal cancer syndrome, the microsatellite instability (MSI) test is recommended as a screening evaluation before proceeding to genetic testing. The MSI test is new to the medical setting, but will be increasingly used to screen patients at high risk for hereditary nonpolyposis colorectal cancer. The main goals of this study were to examine knowledge about and exposure to the MSI test among individuals considering the test, to evaluate perceived benefits and barriers to undergoing the MSI test, and to identify the demographic, medical, and psychosocial correlates of the perceived benefits and barriers to undergoing the test. One hundred and twenty-five patients completed a survey after being offered the test, but prior to making the decision whether to pursue MSI testing. Results indicated low levels of knowledge about and previous exposure to the MSI test. Participants held positive attitudes about the potential benefits of the test and perceived few barriers to undergoing the test. Motivations were similar to those cited by individuals considering other genetic tests. Participants with nonmetastatic disease, with lower perceived risk for cancer recurrence, and who reported more self-efficacy endorsed more benefits from the test. Higher levels of cancer-specific psychological distress were associated with more perceived barriers to having the test. These findings suggest that individuals considering the MSI test know very little about it but hold positive attitudes about the test's utility. More distressed patients, patients who perceive themselves at higher risk for cancer recurrence, and patients with metastatic disease might be less motivated to have the MSI test.  相似文献   
944.
945.
BACKGROUND: Treatment-related neurotoxicity has been recognized as a significant problem in patients with primary central nervous system lymphoma (PCNSL) as effective treatment has increased survival rates. There is, however, a paucity of research on cognitive functions in this population. DESIGN: In a review of the literature, a total of 17 articles that described cognitive outcome in adult PCNSL patients were identified. RESULTS: The studies that assessed cognitive functions after whole-brain radiotherapy combined with chemotherapy reported cognitive impairment in most patients. Patients treated with chemotherapy alone had either stable or improved cognitive performance in most studies. Methodological problems, however, limited the ability to ascertain the specific contribution of disease and various treatment interventions to cognitive outcome. On the basis of the literature review, a battery of cognitive and quality-of-life (QoL) measures to be used in prospective clinical trials was proposed. The battery is composed of five standardized neuropsychological tests, covering four domains sensitive to disease and treatment effects (attention, executive functions, memory, psychomotor speed), and QoL questionnaires, and meets criteria for use in collaborative trials. CONCLUSION: The incorporation of formal and systematic cognitive evaluations in PCNSL studies will improve our understanding of treatment-related neurotoxicity in this population.  相似文献   
946.
Background Retinitis pigmentosa belongs to a large group of degenerative diseases of the retina with a hereditary background. It involves loss of retinal photoreceptor cells and consequently peripheral vision. At present there are no satisfactory therapeutic options for this disease. Just recently the use of mesenchymal stem cells has been discussed as one therapeutical option for retinal degeneration, as they have been shown to differentiate into various cell types, including photoreceptor cells. In this article we wanted to investigate the potency of mesenchymal stem cells to induce rescue effects in an animal model for retinitis pigmentosa, the rhodopsin knockout mouse. Methods For the experiments, three experimental groups of 10 animals each were formed. The first group consisted of untreated rhodopsin knockout (rho-/-) animals used as controls. The second group consisted of rho-/- mice that had received an injection of mouse mesenchymal stem cells, which were transduced using an adenoviral vector containing the sequence for the green fluorescent protein (GFP) prior to transplantation. In the third sham group, animals received an injection of medium only. Thirty-five days after transplantation, GFP-expressing cells were detected in whole-mount preparations of the retinas as well as in cryostat sections. For the detection of rescue effects, semi-thin sections of eyes derived from all experimental groups were produced. Furthermore, rescue effects were also analysed ultrastructurally in ultrathin sections. Results Histological analysis revealed that after transplantation, cells morphologically integrated not only into the retinal pigment epithelium but also into layers of the neuroretina displaying neuronal and glial morphologies. Furthermore, significant rescue effects, as demonstrated by the occurrence of preserved photoreceptor cells, were detected. Conclusions Our data indicate that mesenchymal stem cells can prolong photoreceptor survival in the rhodopsin knockout mouse, also providing evidence of a therapeutical benefit in retinitis pigmentosa. This work was funded by “Pro Retina”.  相似文献   
947.
Nearly 100 experts from all over China attended the Chinese National Conference on Drug Dependence in Sanya/Hainan. The participants came from drug abuse treatment centers, methadone clinics and drug research institutes. The conference's focus was on the question how drug abuse treatment shall and might be part of HIV prevention. CHINALi xiao(The Federal Drug Commissioner with the Federal Ministry of Health, Berlin)  相似文献   
948.
Our objective was to investigate longitudinally, antibodies against central nervous tissue (anti-CNS) derived from bovine brain and gangliosides GM 1, GD1a, GD1b, and GT1b in 91 patients with connective tissue diseases (systemic lupus erythematosus, n = 38; mixed connective tissue disease, n = 16; primary Sjogren's syndrome, n = 7; progressive systemic sclerosis, n= 13; polymyositis/dermatomyositis, n=4; overlap syndrome, n = 5; undifferentiated connective tissue disease, n = 8). Anti-CNS and anti-ganglioside antibodies, measured by enzyme-linked immunosorbent assay, were found in 73% and 63% of patients, respectively. Anti-CNS positive sera were also reactive in Western blotting in 74% of cases and recognized up to 14 different polypeptides from 29 to 130 kDa. Anti-CNS and anti-ganglioside antibodies reflected only in a limited extent the disease activity. In 27 of 58 patients, anti-CNS antibodies remained positive independently of disease activity and antibody levels did not correlate with the phases of exacerbations. A total of 36 of 60 anti-CNS-positive patients, in contrast to two of 22 anti-CNS-negative patients, had major neuropsychiatric manifestations (P < 0.001). Anti-ganglioside antibodies were not significantly associated with neuropsychiatric manifestations. In conclusion, our longitudinal data suggest that anti-CNS antibodies may be an important marker for the diagnosis of cerebral involvement in connective tissue diseases, but the pathogenic role of these autoantibodies remains to be determined.  相似文献   
949.
PURPOSE: Recent studies impressively showed the diagnostic potential of seroreactivity patterns for different tumor types, offering the prospect for low-cost screening of numerous tumor types simultaneously. One of the major challenges toward this goal is to prove that seroreactivity profiles do not only allow for identifying a tumor but also allow for distinguishing tumors from other pathologies of the same organ. EXPERIMENTAL DESIGN: We chose glioma as a model system and tested 325 sera (88 glioma, 95 intracranial tumors, 60 other brain pathologies, and 82 healthy controls) for seroreactivity on a panel of 35 antigens. RESULTS: We were able to discriminate between glioma and all other sera with cross-validated specificity of 86.1%, sensitivity of 85.2%, and accuracy of 85.8%. We obtained comparably good results for the separation of glioma versus nontumor brain pathologies and glioma versus other intracranial tumors. CONCLUSION: Our study provides first evidence that seroreactivity patterns allow for an accurate discrimination between a tumor and pathologies of the same organ even between different tumor types of the same organ.  相似文献   
950.
Adult polyglucosan body disease is a clinicopathologic entity characterized by progressive upper and lower motor neuron dysfunction, sensory loss in the lower extremities, sphincter dysfunction, and occasionally dementia. Pathologically, numerous large polyglucosan bodies are noted in peripheral nerves, cerebral hemispheres, and the spinal cord, as well as in other systemic tissues. We present a case of probable adult polyglucosan body disease based on clinical history and examination, magnetic resonance images, and sural nerve biopsy findings.  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