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   703篇
  免费   33篇
  国内免费   39篇
耳鼻咽喉   1篇
儿科学   29篇
妇产科学   7篇
基础医学   71篇
口腔科学   18篇
临床医学   81篇
内科学   178篇
皮肤病学   8篇
神经病学   42篇
特种医学   167篇
外科学   47篇
综合类   15篇
预防医学   19篇
眼科学   5篇
药学   59篇
肿瘤学   28篇
  2023年   1篇
  2022年   1篇
  2021年   5篇
  2020年   3篇
  2019年   4篇
  2018年   11篇
  2017年   11篇
  2016年   6篇
  2015年   9篇
  2014年   17篇
  2013年   17篇
  2012年   21篇
  2011年   21篇
  2010年   26篇
  2009年   29篇
  2008年   12篇
  2007年   37篇
  2006年   19篇
  2005年   10篇
  2004年   6篇
  2003年   7篇
  2002年   10篇
  2001年   9篇
  2000年   7篇
  1999年   14篇
  1998年   51篇
  1997年   44篇
  1996年   39篇
  1995年   29篇
  1994年   25篇
  1993年   35篇
  1992年   11篇
  1991年   13篇
  1990年   10篇
  1989年   27篇
  1988年   19篇
  1987年   22篇
  1986年   12篇
  1985年   19篇
  1984年   14篇
  1983年   15篇
  1982年   14篇
  1981年   16篇
  1980年   18篇
  1979年   2篇
  1978年   8篇
  1977年   7篇
  1976年   7篇
  1975年   4篇
  1973年   1篇
排序方式: 共有775条查询结果,搜索用时 15 毫秒
1.
2.
The latest remarkable technological advances in assisted reproduction, which enable cryopreservation of spermatozoa, embryos and ovarian tissue, raise difficult and debatable legal, social, ethical and moral issues concerning the right to posthumous reproduction. Furthermore, reports on the attitudes of the general public and of centres licensed for infertility treatment in the United Kingdom found that the majority of women and centres support the idea of posthumous reproduction. In this paper we review the data published on this issue, and after considering the various aspects, we conclude that each case should be discussed and authorized by a multidisciplinary committee that includes physicians, clergy, psychiatrists, psychologists, sociologists and other appropriate parties. In our opinion, the main principles that should guide this committee would allow posthumous reproduction in the context of marriage when a prior consent exists. For unmarried persons, post-mortem donation of gametes should be done only anonymously, if they are in agreement with existing laws concerning infertility treatments in every country and after appropriate consent and proper counselling. Moreover, any case which involves consanguinity or a possibility of incest should be forbidden, both for ethical and genetic reasons. In a case of pre-existing siblings, they should be consulted and their informed consent should be granted in advance so as to avoid legal problems in the inheritance of property.   相似文献   
3.
Preimplantation genetic diagnosis principles and ethics   总被引:4,自引:0,他引:4  
  相似文献   
4.
The nucleocapsid (N) protein of SARS-coronavirus (SARS-CoV) is the key protein for the formation of the helical nucleocapsid during virion assembly. This protein is believed to be more conserved than other proteins of the virus, such as spike and membrane glycoprotein. In this study, the N protein of SARS-CoV was expressed in Escherichia coli DHSalpha and identified with pooled sera from patients in the convalescence phase of SARS. A plasmid pCI-N, encoding the full-length N gene of SARS-CoV, was constructed. Expression of the N protein was observed in COS1 cells following transfection with pCI-N. The immune responses induced by intramuscular immunization with pCI-N were evaluated in a murine model. Serum anti-N immunoglobutins and splenocytes proliferative responses against N protein were observed in immunized BALB/c mice. The major immunoglobulin G subclass recognizing N protein was immunoglobulin G2a, and stimulated splenocytes secreted high levels of gamma interferon and IL-2 in response to N protein. More importantly, the immunized mice produced strong delayed-type hypersensitivity (DTH) and CD^8+ CTL responses to N protein.  相似文献   
5.
6.
ObjectivesEpithelial-mesenchymal transition (EMT) is known to play an important role in the development of tumor invasion and progression in tumors of epithelial origin. Our aim was to investigate the role of tight junction proteins, Par3/Par6/atypical protein kinase C (APKC), Discs large (Dlg), and Scribble in human bladder pathogenesis.MethodsWe evaluated levels of APKC, Dlg, and Scribble in 92 superficial bladder tumors using tissue microarrays and immunohistochemistry, and correlated expression with pathologic variables and clinical outcomes.ResultsThere was a slight apparent enrichment in strong vs. weak staining for APKC (54.9% vs. 45.1%), Dlg (65.7% vs. 34.3%), and a marked enrichment for Scribble (75% vs. 25%) in the superficial bladder tumors. Univariate analysis determined that both tumor focality and APKC expression were significantly associated with tumor recurrence (P < 0.05). Multivariate analysis using the Cox's proportional hazards model revealed that only APKC (P = 0.025) as well as tumor focality (P = 0.018) were independent and significant prognostic factors for tumor recurrence in all patients. We found that no immunohistochemical staining of any of the cell polarity proteins significantly predicted for tumor progression on either univariate or multivariate analysis.ConclusionsLoss of APKC expression in superficial bladder tumors is a strong predictor of tumor recurrence.  相似文献   
7.
Objective To explore the characteristics of arrhythmogenic right ventricular cardiomyopathy (ARVC). Methods Seven patients with arrhythmogenic right ventricular cardiomyopathy and 34 members of three families were studied. All patients and family members underwent history collection, clinical examination, electrocardiogram (ECG), two-dimensional echocardiography (2-DE) and a signal averaging electrocardiogram. Programmed ventricular stimulation was performed in five patients. Results All patients and family members had normal morphologic characteristics and normal function of the left ventricular by 2-DE. Fourteen persons had abnormal findings indicating ARVC. Five had enlargement of the right ventricular with diffused hypocontractility, eight had thin and systolic bulging in the focal anterior wall with hypokinesia and one had bulging of the inferior wall. Twenty-five persons (seven patients and 18 family members) had abnormal findings in ECG. Positive ventricular late potential was recorded in 13 persons (six patients). Two to three monomorphic ventricular tachycardia (VT) with left bundle branch block (LBBB) configurations were induced in five patients. Ventricular fibrillation was induced in two patients during the electrophysiologic study (EPS). Five patients had very high pacing threshold and/or ineffective pacing in one or many regions of the right ventricle. Two members of one family died suddenly. One member was a dwarf with ARVC. Spontaneous VT with a left bundle branch block (LBBB) configuration was recorded in five patients, polymorphic VT with extremely short coupling interval in one, and premature ventricular complexes with LBBB configuration in 12 (six patients). Conclusion Our familial study strongly suggests that ARVC may be a hereditary disease and it is helpful in the diagnosis and detection of ARVC. The most common manifestations were abnormal structure and function of the right ventricle and abnormal ECG of repolarization and ventricular arrhythmia which originates from the right ventricle.  相似文献   
8.
Castle  V; Coates  G; Kelton  JG; Andrew  M 《Blood》1987,70(3):652-656
Thrombocytopenia is a common occurrence (20%) in sick neonates, but the causes have not been well studied. In this report we demonstrate that thrombocytopenia in the neonate is characterized by increased platelet destruction as shown by shortened homologous 111In-oxine-labeled platelet life spans. Thirty-one prospectively studied thrombocytopenic neonates were investigated by measuring the 111In-labeled platelet life span, platelet-associated IgG (PAIgG), and coagulation screening tests. In every infant, the thrombocytopenia was shown to have a destructive component since the mean platelet life span was significantly shortened to 65 +/- 6 (mean +/- SEM) hours with a range of one to 128 hours compared with adult values (212 +/- 8; range, 140 to 260; gamma function analysis). The platelet survival was directly related to the lowest platelet count and inversely related to both the highest mean platelet volume and duration of the thrombocytopenia. In 22 infants the percent recovery of the radiolabeled platelets was less than 50%, which suggested that increased sequestration also contributed to the thrombocytopenia. Infants with laboratory evidence of disseminated intravascular coagulation (n = 8) or immune platelet destruction evidenced by elevated levels of PAIgG (n = 13) had even shorter platelet survivals and a more severe thrombocytopenia compared with the ten infants in whom an underlying cause for the thrombocytopenia was not apparent. Full-body scintigraphic images obtained in 11 infants showed an increased uptake in the spleen and liver, with a spleen-to- liver ratio of 3:1. This study indicates that thrombocytopenia in sick neonates is primarily destructive, with a subgroup having evidence of increased platelet sequestration.  相似文献   
9.
Heparin-induced thrombocytopenia is characterized by moderate thrombocytopenia and thrombotic complications, whereas quinine/quinidine-induced thrombocytopenia usually presents with severe thrombocytopenia and bleeding. Using flow cytometry and assays of procoagulant activity, we investigated whether sera from patients with these immune drug reactions could stimulate normal platelets to generate platelet-derived microparticles with procoagulant activity. Sera or purified IgG from patients with heparin-induced thrombocytopenia stimulated the formation of platelet-derived microparticles in a heparin-dependent fashion. Further studies showed that heparin-induced thrombocytopenia sera also produced a marked increase in procoagulant activity. In contrast, sera from patients with quinine- or quinidine-induced thrombocytopenia did not generate platelet-derived microparticles nor generate increased procoagulant activity. However, quinine/quinidine-induced thrombocytopenia sera produced a significant increase in the binding of IgG to platelets in a drug-dependent fashion, whereas sera from patients with heparin-induced thrombocytopenia demonstrated no drug-dependent binding of IgG to platelets. We also observed increased levels of circulating microparticles in patients with acute heparin-induced thrombocytopenia compared with control patients. Our observations indicate that the generation of procoagulant platelet-derived microparticles in vivo is a plausible explanation for the thrombotic complications observed in some patients with heparin-induced thrombocytopenia.  相似文献   
10.
蝙蝠葛中的新生物碱——蝙蝠葛新林碱   总被引:3,自引:0,他引:3  
防已科植物蝙蝠葛(Menispermum daurioum DC.)的根茎,即北豆根,是一种重要的中药,具有清热解毒、消肿止痛等功效。已知含有近二十种生物碱,其中五种属双苄基四氢异喹啉类,即蝙蝠葛碱(dauricine,Ⅰ)、蝙蝠葛诺林碱(daurinoline,Ⅱ)、蝙蝠葛新诺林碱  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