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   21635篇
  免费   1743篇
  国内免费   49篇
耳鼻咽喉   111篇
儿科学   854篇
妇产科学   715篇
基础医学   3033篇
口腔科学   321篇
临床医学   2936篇
内科学   3846篇
皮肤病学   286篇
神经病学   2616篇
特种医学   318篇
外科学   1774篇
综合类   267篇
一般理论   47篇
预防医学   2943篇
眼科学   390篇
药学   1469篇
中国医学   28篇
肿瘤学   1473篇
  2023年   215篇
  2022年   243篇
  2021年   474篇
  2020年   353篇
  2019年   548篇
  2018年   596篇
  2017年   467篇
  2016年   476篇
  2015年   543篇
  2014年   787篇
  2013年   1117篇
  2012年   1606篇
  2011年   1667篇
  2010年   895篇
  2009年   855篇
  2008年   1362篇
  2007年   1502篇
  2006年   1492篇
  2005年   1393篇
  2004年   1361篇
  2003年   1246篇
  2002年   1153篇
  2001年   174篇
  2000年   126篇
  1999年   158篇
  1998年   231篇
  1997年   194篇
  1996年   147篇
  1995年   137篇
  1994年   106篇
  1993年   128篇
  1992年   87篇
  1991年   78篇
  1990年   67篇
  1989年   66篇
  1988年   58篇
  1987年   53篇
  1986年   47篇
  1985年   54篇
  1984年   55篇
  1983年   74篇
  1982年   81篇
  1981年   71篇
  1980年   73篇
  1979年   51篇
  1978年   45篇
  1977年   40篇
  1976年   48篇
  1974年   40篇
  1973年   44篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
61.
Adoptive immunotherapy for posttransplantation viral infections.   总被引:1,自引:0,他引:1  
Viral diseases are a major cause of morbidity and mortality after hemopoietic stem cell transplantation. Because viral complications in these patients are clearly associated with the lack of recovery of virus-specific cellular immune responses, reconstitution of the host with in vitro expanded cytotoxic T lymphocytes is a potential approach to prevent and treat these diseases. Initial clinical studies of cytomegalovirus and Epstein-Barr virus in human stem cell transplant patients have shown that adoptively transferred donor-derived virus-specific T cells may restore protective immunity and control established infections. Preclinical studies are evaluating this approach for other viruses while strategies for generating T cells specific for multiple viruses to provide broader protection are being evaluated in clinical trials. The use of genetically modified T cells or the use of newer suicide genes may result in improved safety and efficacy.  相似文献   
62.
Herbal remedies generate more than 1.8 billion dollars in annual sales in the United States. Herbal products have been associated with a wide spectrum of hepatic toxicities. With the recent Women's Health Initiative Study demonstrating increased risk of breast cancer and cardiovascular events associated with hormone therapy, many women may resort to herbal remedies for persistent menopause symptoms. We report a case of autoimmune hepatitis likely triggered by the use of black cohosh (Actaea racemosa), an agent marketed to treat menopause symptoms. Given this case report, we recommend close monitoring of women using this herbal preparation.  相似文献   
63.
Five TLRs are thought to play an important role in antiviral immunity, sensing viral products and inducing IFN-alpha/beta and -lambda. Surprisingly, patients with a defect of IRAK-4, a critical kinase downstream from TLRs, are resistant to common viruses. We show here that IFN-alpha/beta and -lambda induction via TLR-7, TLR-8, and TLR-9 was abolished in IRAK-4-deficient blood cells. In contrast, IFN-alpha/beta and -lambda were induced normally by TLR-3 and TLR-4 agonists. Moreover, IFN-beta and -lambda were normally induced by TLR-3 agonists and viruses in IRAK-4-deficient fibroblasts. We further show that IFN-alpha/beta and -lambda production in response to 9 of 11 viruses tested was normal or weakly affected in IRAK-4-deficient blood cells. Thus, IRAK-4-deficient patients may control viral infections by TLR-3- and TLR-4-dependent and/or TLR-independent production of IFNs. The TLR-7-, TLR-8-, and TLR-9-dependent induction of IFN-alpha/beta and -lambda is strictly IRAK-4 dependent and paradoxically redundant for protective immunity to most viruses in humans.  相似文献   
64.

Background  

Previous publications indicate that acupuncture is efficient for the treatment of pelvic girdle pain, PGP, in pregnant women. However, the use of acupuncture for PGP is rare due to insufficient documentation of adverse effects of this treatment in this specific condition. The aim of the present work was to assess adverse effects of acupuncture on the pregnancy, mother, delivery and the fetus/neonate in comparison with women that received stabilising exercises as adjunct to standard treatment or standard treatment alone.  相似文献   
65.
BACKGROUND: Surveys of the public in several countries have found that negative attitudes towards antidepressants are common. However, there has been little research into the factors associated with these attitudes. METHODS: A national survey of 999 Australian adults assessed beliefs about the helpfulness or harmfulness of antidepressants for a person with depression and suicidal thoughts. Associated factors investigated were as follows: sociodemographic characteristics, exposure to depression, ability to recognize depression, beliefs about other depression interventions, beliefs about long-term outcomes with and without treatment, beliefs about causes, and stigmatizing attitudes. RESULTS: Around a quarter of Australian adults believe that antidepressants would be harmful for a person who is depressed and suicidal. This group was less educated, had less exposure to depression, showed poorer recognition of depression, was less favorable about other standard interventions including psychological ones, was less pessimistic about the long-term outcome if the person did not have treatment, and was more likely to see depression as due to weakness and to be under the individual's control. LIMITATIONS: The survey did not directly ask about reasons for believing that antidepressants would be harmful. CONCLUSIONS: Belief in the harmfulness of antidepressants is associated with a general lack of exposure to depression, leading to an underestimation of its seriousness and of the necessity for intervention.  相似文献   
66.
Genetic linkage analysis has been instrumental in mapping thegene for X-linked agammaglobulinemia (XLA) to the proximal longarm of the human X chromosome, to Xq22. Due to the relativerarity of this disease the localization of the gene within Xq22has remained imprecise. We have investigated twenty-nine familiesaffected by XLA and have found no recombinants with the DXS178locus in over 30 informative meioses. DXS178 is now the mostreliable and informative locus for use in pre-natal diagnosisand carrier detection of XLA. In addition, we have identifiednew closely linked proximal and distal flanking markers forXLA, DXS442 and DXS101, respectively. These loci are separatedby 2cM, considerably reducing the extent of DNA within whichthe XLA locus can be contained. This will open up the way formore directed positional cloning efforts for the isolation ofthe XLA gene.  相似文献   
67.
Summary Techniques have been developed for collection of urine in embryonic and newly hatched chickens for the purpose of studying the development of renal function.The reliability of EDTA-51Cr as a substitute for inulin-14C in the determination of GFR was studied. Since inulin and EDTA-51Cr clearances in the hatched chicken averaged 1.61±0.23 (S.E.) ml/min per kg body weight and 1.58±0.27 ml/min per kg body weight, respectively, EDTA-51Cr clearance was considered a suitable measure of GFR.GFR increased significantly in the first few days after hatching. Filtration rate was 0.068±0.008 (S.E.) ml/min per g kidney weight in the embryo and increased to 0.148±0.008 ml/min per g shortly after hatching. By nine days after hatching GFR had risen to 0.290±0.015 ml/min per g, a value comparable to that reported for the adult.Clearances of sodium, potassium, chloride and total osmolyte also increased with age. When these clearances were corrected for changing glomerular filtration rates the embryonic chicks were found to excrete a greater percentage of the filtered load. These results show that adult levels of glomerulo-tubular balance are not attained until after hatching.A preliminary report of this work has already been published [3].  相似文献   
68.
Induced genomic instability in the human B lymphoblastoid cell line TK6 manifests itself as increases in end-to-end chromosome fusions and non-reciprocal chromosome translocations. It is not associated with elevated frequencies of specific locus mutations or other cytogenetic alterations. Previous studies on a limited number of cells and end-points suggested that induced instability in TK6 mirrors spontaneous instability in terms of the types of alterations observed. In the present study we expanded on our previous analysis to include more cells and more end-points in order to derive a more precise measure of spontaneous instability in TK6 cells. The frequency of normal growth rate thymidine kinase mutants (TK(-/-)), measured in 44 independently isolated clones, was 2.73 +/- 0.78 x 10(-6)/cell, while that for slow growth mutants was 2.39 +/- 0.52 x 10(-6)/cell. These are similar to the frequencies observed for HPRT mutants in primary human cells. There was wide variation in chromatid break frequencies, but the average break frequency, at 0.04+/-0.01 breaks/cell, was only slightly higher than that reported for primary human cells. In contrast, the dicentric frequency of 0.006/cell was more than 10-fold higher for TK6 cells than that reported for normal primary human cells. Furthermore, the dicentrics in TK6 cells are unusual in that they are the result of end-to-end chromosome fusions. TK6 cells also show much higher levels of non-reciprocal chromosome translocations than are usually observed in primary human cells. The results suggest an inherent instability in TK6 cells that differs from what is observed in primary cells in that it affects the frequency of end-to-end chromosome fusions and non-reciprocal chromosome translocations, but not TK gene mutations or other cytogenetic alterations.  相似文献   
69.
70.
The role of del (11)(p13) as a cause of aniridia, with and without Wilms tumor, is strengthened by demonstration of this chromosome aberration in 3 patients: monozygous twin girls, both of whom have aniridia and mental retardation and one of whom has a Wilms tumor; and an unrelated boy with aniridia and ambiguous genitalia. The break points defining the interstitial deletion for the twins are 11p13 and 11p15.1, while for the boy they are 11p1302 and 11p14.1. These patients and their karyotypes substantiate the critical importance of chromosome band 11p13 (or its hemizygous representation) in the development of aniridia and an associated Wilms tumor diathesis, as had been suggested previously (Riccardi VM, Sujansky E, Smith AC, Francke U, (1978): Pediatrics 61, 604-610).  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