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   2945篇
  免费   132篇
  国内免费   27篇
耳鼻咽喉   10篇
儿科学   67篇
妇产科学   29篇
基础医学   363篇
口腔科学   146篇
临床医学   191篇
内科学   761篇
皮肤病学   101篇
神经病学   220篇
特种医学   30篇
外科学   486篇
综合类   10篇
一般理论   1篇
预防医学   44篇
眼科学   140篇
药学   173篇
中国医学   12篇
肿瘤学   320篇
  2023年   17篇
  2022年   23篇
  2021年   59篇
  2020年   27篇
  2019年   58篇
  2018年   68篇
  2017年   54篇
  2016年   69篇
  2015年   57篇
  2014年   79篇
  2013年   83篇
  2012年   118篇
  2011年   164篇
  2010年   97篇
  2009年   85篇
  2008年   128篇
  2007年   154篇
  2006年   139篇
  2005年   140篇
  2004年   133篇
  2003年   146篇
  2002年   130篇
  2001年   103篇
  2000年   73篇
  1999年   108篇
  1998年   46篇
  1997年   43篇
  1996年   22篇
  1995年   13篇
  1994年   29篇
  1993年   25篇
  1992年   60篇
  1991年   45篇
  1990年   56篇
  1989年   51篇
  1988年   43篇
  1987年   39篇
  1986年   32篇
  1985年   30篇
  1984年   28篇
  1983年   26篇
  1980年   15篇
  1979年   12篇
  1978年   20篇
  1976年   11篇
  1974年   11篇
  1972年   12篇
  1971年   12篇
  1969年   12篇
  1967年   14篇
排序方式: 共有3104条查询结果,搜索用时 19 毫秒
91.
92.
Hokoei-to (pugongying-tang) is one of the Kampo formulae clinically used for gynecological disturbances such as lack of lactation and mammary swelling. We investigated the effect of hokoei-to on the nervous and immune systems in ovariectomized mice as a climacteric disorder model. Hokoei-to suppressed the decrease of monoamines in the ventral hippocampus and dorsal hippocampus of ovariectomized mice. It was shown that the hokoei-to could improve the metabolic turnover of dopamine. The mitogenic activity of lymphocytes in the spleen was reduced after ovariectomy; a suppression of this reduced activity was observed in the group given hokoei-to.  相似文献   
93.
94.
Alzheimer’s disease (AD) is the most common form of senile dementia. Aggregation of the amyloid-β42 peptide (Aβ42) and tau proteins are pathological hallmarks in AD brains. Accumulating evidence suggests that Aβ42 plays a central role in the pathogenesis of AD, and tau acts downstream of Aβ42 as a modulator of the disease progression. Tau pathology is also observed in frontotemporal dementia with Parkinsonism linked to chromosome 17 (FTDP-17) and other related diseases, so called tauopathies. Although most cases are sporadic, genes associated with familial AD and FTDP-17 have been identified, which led to the development of transgenic animal models. Drosophila has been a powerful genetic model system used in many fields of biology, and recently emerges as a model for human neurodegenerative diseases. In this review, we will summarize key features of transgenic Drosophila models of AD and tauopathies and a number of insights into disease mechanisms as well as therapeutic implications gained from these models.  相似文献   
95.
Classical citrullinemia (CTLN1), a rare autosomal recessive disorder, is caused by mutations of the argininosuccinate synthetase (ASS) gene, localized on chromosome 9q34.1. ASS functions as a rate-limiting enzyme in the urea cycle. Previously, we identified 32 mutations in the ASS gene of CTLN1 patients mainly in Japan and the United States, and to date 34 different mutations have been described in 50 families worldwide. In the present study, we report ASS mutations detected in 35 additional CTLN1 families from 11 countries. By analyzing the entire coding sequence and the intron-exon boundaries of the ASS gene using RT-PCR and/or genomic DNA-PCR, we have identified 16 novel mutations (two different 1-bp deletions, a 67-bp insertion, and 13 missense) and have detected 12 known mutations. Altogether, 50 different mutations (seven deletion, three splice site, one duplication, two nonsense, and 37 missense) in 85 CTLN1 families were identified. On the basis of primary sequence comparisons with the crystal structure of E. coli ASS protein, it may be concluded that any of the 37 missense mutations found at 30 different positions led to structural and functional impairments of the human ASS protein. It has been found that three mutations are particularly frequent: IVS6-2A>G in 23 families (Japan: 20 and Korea: three), G390R in 18 families (Turkey: six, U.S.: five, Spain: three, Israel: one, Austria: one, Canada: one, and Bolivia: one), and R304W in 10 families (Japan: nine and Turkey: one). Most mutations of the ASS gene are "private" and are distributed throughout the gene, except for exons 5 and 12-14. It seems that the clinical course of the patients with truncated mutations or the G390R mutation is early-onset/severe. The phenotype of the patients with certain missense mutations (G362V or W179R) is more late-onset/mild. Eight patients with R86H, A118T, R265H, or K310R mutations were adult/late-onset and four of them showed severe symptoms during pregnancy or postpartum. However, it is still difficult to prove the genotype-phenotype correlation, because many patients were compound heterozygotes (with two different mutations), lived in different environments at the time of diagnosis, and/or had several treatment regimes or various knowledge of the disease.  相似文献   
96.
Amino acid transport systems play an important role in cellular proliferation. L-type amino acid transporter 1 (LAT1) has been associated with tumor growth, and is highly expressed in the established tumor cell lines and primary human neoplasms. In this study, we investigated the expression of LAT1 to evaluate the malignant potential and prognostic significance in neuroendocrine (NE) tumors of the lung. Twenty-one surgically resected, large cell neuroendocrine carcinomas (LCNEC), 13 small cell lung cancers (SCLC), five atypical carcinoids (AC), and 10 typical carcinoids (TC) were enrolled in the study. LAT1 expression and Ki-67 labeling index of the NE tumors were analyzed by immunohistochemical staining. LAT1 was overexpressed in 52.4% of the LCNEC, in 46.2% of the SCLC, and in 25% of the AC. LAT1 expression in LCNEC was significantly associated with lymph node metastasis and poor outcome. Moreover, a significant correlation was found between LAT1 expression and Ki-67 in both LCNEC and SCLC. Expression of LAT1 tended to increase from low-grade to high-grade NE tumors. The present results suggest that LAT1 may play a significant role in cellular proliferation, lymph node metastasis, and poor outcome in patients with NE tumors of the lung.  相似文献   
97.
98.
BACKGROUND: Although increased nitric oxide (NO) production in asthma is mediated largely by upregulation of the inducible form of nitric oxide synthase (iNOS, or NOS 2), some studies have suggested an important role for the usually constitutive neural NOS isoform (nNOS, or NOS 1). AIM: To investigate how NOS 1 may influence allergic inflammation, we used NOS 1 knockout mice and their wild-type (WT) controls. METHODS: Mice were sensitized and challenged with ovalbumin (OVA) using a protocol known to upregulate NOS 2 in the airways. RESULTS: In addition to expected increases in NOS 2 activity, OVA challenge led to increases in calcium-dependent NOS activity, which was accounted for by increased expression of NOS 1 at both mRNA (n = 5, p < 0.001) and protein levels (n = 5, p < 0.01). In NOS-1-deficient mice, OVA challenge induced less eosinophilia (n = 7, p < 0.05) and much less NO production (n = 10, p < 0.01) than in WT controls, reflecting not only the expected absence of NOS 1, but also lack of upregulation of NOS 2. This interaction appeared to be stimulus specific as NOS-1-deficient mice did upregulate NOS 2 following exposure to lipopolysaccharide (n = 5, p < 0.001). CONCLUSIONS: These findings underscore the importance of NOS 1 in allergic airway inflammation and suggest a mechanism by which NOS 1 may influence overall NO production in the airways.  相似文献   
99.
BACKGROUND: Allergic asthma is an increasing clinical problem that might be addressed with immunologically based interventions. A novel human antibody that activates human and mouse dendritic cells (DCs) by cross-linking B7-DC has strong immunomodulatory properties and blocks antigen-induced inflammatory lung disease in mice. OBJECTIVE: We sought to evaluate the ability of activated DCs to mediate an antibody-induced protective response against inflammatory lung disease. METHODS: An adoptive transfer strategy was used to test the ability of antibody treatments to activate DCs, inducing a protective response against inflammatory lung disease in mice presensitized to ovalbumin (OVA). After transfer of activated DCs, recipient mice were exposed repeatedly to airway antigen and evaluated for changes in immune reactivity and airway inflammatory disease. RESULTS: Animals presensitized to OVA receiving either systemic treatments with B7-DC cross-linking antibody (XAb) or adoptively transferred antibody-activated DCs were completely protected from airway inflammatory responses normally induced by repeated exposure to OVA. Lymphocytes isolated from spleens or lung-draining lymph nodes of treated animals were highly responsive to OVA and secreted TNF-alpha, IFN-gamma, and IL-10. In contrast, IL-4 was not produced by cells isolated from animals receiving B7-DC XAb. CONCLUSION: Activation of DCs with B7-DC XAb ex vivo before adoptive transfer into presensitized mice is sufficient to protect animals completely from inflammatory lung disease induced by subsequent repeated airway exposure to the offending antigen. This finding is consistent with our hypothesis that in vivo administration of B7-DC XAb modulates the immune response by activating endogenous DCs.  相似文献   
100.
Several therapies including immunosuppressive agents have been shown to be effective and safe for frequently relapsing nephrotic syndrome/steroid‐dependent nephrotic syndrome (FRNS/SDNS) and steroid‐resistant nephrotic syndrome in children. It is evident, however, that a substantial number of children are still refractory to treatment despite these therapies. Rituximab is a chimeric monoclonal antibody, which inhibits CD20‐mediated B‐cell proliferation and differentiation. It was first introduced for the treatment of B‐cell non‐Hodgkin's lymphoma and was subsequently administered to patients with autoimmune diseases, such as rheumatoid arthritis, lupus erythematosus, or immunocomplex glomerulonephritis. Recently, a number of case reports and non‐controlled clinical trials have suggested that rituximab may be effective for children with refractory nephrotic syndrome. Controlled prospective trials, however, are required to establish the value of rituximab in refractory nephrotic syndrome. The purpose of the present study was therefore to evaluate the efficacy and safety of rituximab in childhood‐onset refractory nephrotic syndrome. The Research Group of Childhood‐onset Refractory Nephrotic Syndrome (RCRNS) conducted a randomized, double‐blind, placebo‐controlled, multi‐center clinical trial (RCRNS‐01) and an open‐label, multi‐center, pharmacokinetic clinical trial (RCRNS‐02). These two trials were investigator‐initiated, registration‐directed clinical trials designed to apply Ministry of Health, Labour and Welfare approval for the use of rituximab for childhood‐onset refractory FRNS/SDNS in Japan. RCRNS‐01 could be the first study to clarify whether rituximab is effective and safe for childhood‐onset refractory FRNS/SDNS.  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