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   1217篇
  免费   77篇
  国内免费   17篇
耳鼻咽喉   4篇
儿科学   69篇
妇产科学   13篇
基础医学   142篇
口腔科学   23篇
临床医学   153篇
内科学   226篇
皮肤病学   7篇
神经病学   123篇
特种医学   105篇
外科学   216篇
综合类   15篇
一般理论   1篇
预防医学   80篇
眼科学   10篇
药学   43篇
中国医学   3篇
肿瘤学   78篇
  2021年   23篇
  2020年   11篇
  2019年   21篇
  2018年   22篇
  2017年   21篇
  2016年   16篇
  2015年   17篇
  2014年   22篇
  2013年   44篇
  2012年   41篇
  2011年   44篇
  2010年   38篇
  2009年   48篇
  2008年   42篇
  2007年   52篇
  2006年   44篇
  2005年   48篇
  2004年   51篇
  2003年   27篇
  2002年   41篇
  2001年   31篇
  2000年   31篇
  1999年   23篇
  1998年   37篇
  1997年   28篇
  1996年   26篇
  1995年   20篇
  1994年   25篇
  1993年   14篇
  1992年   18篇
  1991年   19篇
  1990年   30篇
  1989年   31篇
  1988年   30篇
  1987年   22篇
  1986年   17篇
  1985年   25篇
  1984年   19篇
  1983年   12篇
  1982年   14篇
  1981年   8篇
  1980年   9篇
  1978年   15篇
  1977年   7篇
  1976年   8篇
  1973年   7篇
  1971年   7篇
  1969年   8篇
  1968年   8篇
  1967年   8篇
排序方式: 共有1311条查询结果,搜索用时 21 毫秒
1.
BACKGROUND: On December 26, 2004, the biggest earthquake for 40 years, measuring 9.0 on the Richter scale, triggered a tsunami that pounded the coastal areas of South Asia and East Africa. The effects of the tsunami on skin conditions have not been evaluated. OBJECTIVE: To determine the influence of the tsunami on skin conditions by evaluating the skin problems of patients presenting at hospitals after the tsunami. METHODS: Between 5 and 25 January 2005, two dermatologists evaluated patients who complained of skin problems at an outpatient clinic and emergency room of a general hospital in Banda Aceh, Aceh Province, Indonesia. RESULTS: The total number of patients that presented during the study period was 235 (131 males and 104 females), and they had a total of 265 skin problems. In terms of age distribution, most subjects were in their fourth decade (23.0%), followed by the third (22.6%) and fifth decade (16.6%). The most prevalent skin problems were infections-infestations (32.5%), followed by eczemas (29.8%) and traumatic skin disorders (29.4%). In males, traumatic skin disorders were most common. The great majority of infection-infestation cases involved superficial fungal infections. Contact dermatitis accounted for three-quarters of eczema cases, and mainly involved the arms (40.0%) and legs (27.1%). The majority of traumatic skin disorders were lacerations, punctures and penetrations, and the feet (44.7%) and hands (18.8%) were most frequently affected. CONCLUSIONS: Unhygienic conditions, exposure to a hazardous environment and contact with various objects during and after the tsunami probably increased the prevalence of infections-infestations, traumatic skin disorders and contact dermatitis. To prevent these problems and associated secondary bacterial infections, health-related education and early medical management are required.  相似文献   
2.
3.
4.
STUDY OBJECTIVE: To test the hypothesis that induced human graafian follicles consist of different steroidogenic cell types on the basis of their light scatter characteristics as determined by flow cytometry. DESIGN: Cross-sectional, observational study. SETTING: Flow cytometry laboratory. PATIENTS: Thirty-six follicular aspirates from nine consecutive patients undergoing in vitro fertilization for tubal factor infertility were evaluated. RESULTS: Two distinct luteal cell populations were recovered. Both populations were positive by Oil Red O staining, suggesting the presence of intracellular lipid. Neither population stained positively for the presence of HLe-1/CD45, an antigen present on all human leukocytes. CONCLUSIONS: Cellular heterogeneity exists within the granulosa cell compartment.  相似文献   
5.
Abstract: Adequate venous access is an essential component of therapeutic plasma exchange (TPEX). The simplest kind of venous access is venipuncture of antecubital veins, but this technique may be limited by venous size or scarring following the procedure, requiring the placement of a specialized vascular access device (VAD). VADs provide reliable central venous access and may remain in place for several weeks or months, depending on the VAD and the venous site chosen. Their use, however, is potentially limited by the risk of complications. We discuss indications for insertion, choice of catheter and access site, and complications of VAD placement for TPEX.  相似文献   
6.
Human chromosome 11p15.5 and distal mouse chromosome 7 include a megabase-scale chromosomal domain with multiple genes subject to parental imprinting. Here we describe mouse and human versions of a novel imprinted gene, IMPT1 , which lies between IPL and p57 KIP2 and which encodes a predicted multi-membrane-spanning protein similar to bacterial and eukaryotic polyspecific metabolite transporter and multi- drug resistance pumps. Mouse Impt1 and human IMPT1 mRNAs are highly expressed in tissues with metabolite transport functions, including liver, kidney, intestine, extra-embryonic membranes and placenta, and there is strongly preferential expression of the maternal allele in various mouse tissues at fetal stages. In post-natal tissues there is persistent expression, but the allelic bias attenuates. An allelic expression bias is also observed in human fetal and post-natal tissues, but there is significant interindividual variation and rare somatic allele switching. The fact that Impt1 is relatively repressed on the paternal allele, together with data from other imprinted genes, allows a statistical conclusion that the primary effect of human chromosome 11p15.5/mouse distal chromosome 7 imprinting is domain-wide relative repression of genes on the paternal homolog. Dosage regulation of the metabolite transporter gene(s) by imprinting might regulate placental and fetal growth.   相似文献   
7.
OBJECTIVE: To compare the prevalence of antibodies to human herpesvirus 8 (HHV-8) or Kaposi sarcoma-associated herpesvirus among Israeli and Ethiopian subjects. METHODS: Serum samples were obtained from 98 Israeli Jewish students aged 18-30 years, 100 HIV-1-seronegative Ethiopian immigrants to Israel of the same age, and 100 HIV-1-seronegative Ethiopian children 1-12 years old upon their arrival in southern Israel. Plasma samples were obtained from 3 hospitalized patients with multicentric Castleman disease (MCD) as positive controls. All serum samples were tested for antibodies to both latent and lytic antigens. Antibodies to the lytic antigens and the latency-associated nuclear antigen (LANA) of HHV-8 were detected by enzyme linked immunosorbent assay and by immunofluorescence assay. HHV-8 DNA from serum or plasma samples was detected by polymerase chain reaction analysis. RESULTS: Antibodies to HHV-8 LANA were detected in 2.9% of the Israeli subjects aged 18-30 years and in 26% of the Ethiopian subjects from both age groups tested. Antibodies to the lytic antigens were detected in all 3 MCD patients, in 4% of the Ethiopian children, and in 2% of the 18- to 30-year-old Ethiopians. No antibodies to the lytic antigens were detected in the Israeli students. HHV-8 DNA was detected in all 3 MCD patients and in 2 of 4 of the Ethiopian children positive for the lytic antigens. CONCLUSIONS: HHV-8 is highly prevalent in Ethiopian immigrants to Israel as compared with Israeli students. Antibodies to HHV-8 in Ethiopia are acquired before puberty. The results of this study indicate the association of HHV-8 with MCD, as has been documented by many other researchers.  相似文献   
8.
Recently, in-vitro maturation (IVM) of immature human oocytes recovered from non-stimulated follicles has been applied in the treatment of infertility. However, in previous reports, very few embryos cultured in conventional medium have reached the expanded blastocyst stage following in-vitro maturation and fertilization (IVM/IVF). The objective of this study was to investigate whether the developmental competence of human embryos following IVM/IVF could be enhanced by the use of a human ampullary cell co-culture system. Immature human oocytes were aspirated from small follicles at Caesarean section and then cultured in medium containing human menopausal gonadotrophin for 36 to 48 h, followed by insemination. Zygotes were randomly cultured either in conventional culture medium alone or in the co-culture system. Of 48 embryos cultured in conventional medium alone, all arrested at the 2-16- cell stage on day 3 after insemination. Of 46 embryos cultured in the co-culture system, 26 embryos (56.5%) arrested at the 2-16-cell stage. Six embryos (13%) developed to the morula stage. Fourteen embryos (30.4%) developed to expanded blastocysts and two blastocysts were hatching on day 7 after insemination. We conclude that co-culture significantly enhances the development of blastocysts in embryos resulting from IVM/IVF.   相似文献   
9.
A role for interferon-gamma (IFN-gamma) has been implied in the atherogenic process. To determine whether exogenously administered IFN-gamma exerts an effect on the development of atherosclerosis, we intraperitoneally administered either recombinant IFN-gamma (100 U/g body weight) or phosphate buffered saline daily for 30 days to atherosclerosis-susceptible apolipoprotein E-/- mice (16-week-old male mice, n = 11 per group) fed a normal diet. Atherosclerotic lesion size was quantified in the ascending aorta. The number of T lymphocytes and major histocompatibility complex (MHC) class II-positive cells within lesions were also quantified in this region. IFN-gamma administration reduced serum cholesterol concentrations by 15% (P = 0.02). For both groups, the majority of cholesterol was present in very low density lipoproteins, which were modestly reduced in mice receiving IFN-gamma. Despite the decrease in serum cholesterol concentrations, IFN-gamma injections significantly increased lesion size twofold compared to controls (119,980 +/- 18, 536 vs. 59,396 +/- 20,017 micrometer(2); P = 0.038). IFN-gamma also significantly increased the mean number of T lymphocytes (19 +/- 4 vs. 7 +/- 1 cells; P = 0.03) and MHC class II-positive cells (10 +/- 3 vs. 3 +/- 1 cells; P = 0.04) within lesions. These data lend further support to a pro-atherogenic role of IFN-gamma.  相似文献   
10.
The MHC class I molecule plays a crucial role in cytotoxic lymphocyte function. The heavy chain of the MHC class I molecule can form many non-covalent interactions with other molecules on multiple domains and surfaces. We have generated an isolated alpha3 domain of a murine MHC class I molecule and evaluated the contribution of this domain to binding with the MHC class I light chain, beta2m, and CD8. The alpha3 domain binds beta2m at a thousand-fold higher concentration than the whole MHC, and binds CD8alphaalpha with a dependence on the alpha3 CD loop. Our results are relevant for models of MHC folding and CD8-MHC function. The study of individual domains of complex molecules is an important strategy for understanding their dynamic structure and function.  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