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   7074篇
  免费   930篇
  国内免费   12篇
耳鼻咽喉   45篇
儿科学   153篇
妇产科学   126篇
基础医学   967篇
口腔科学   139篇
临床医学   734篇
内科学   1565篇
皮肤病学   96篇
神经病学   623篇
特种医学   364篇
外科学   1070篇
综合类   117篇
一般理论   6篇
预防医学   852篇
眼科学   64篇
药学   611篇
中国医学   2篇
肿瘤学   482篇
  2023年   64篇
  2022年   71篇
  2021年   244篇
  2020年   128篇
  2019年   202篇
  2018年   235篇
  2017年   200篇
  2016年   183篇
  2015年   153篇
  2014年   224篇
  2013年   273篇
  2012年   366篇
  2011年   415篇
  2010年   208篇
  2009年   174篇
  2008年   258篇
  2007年   276篇
  2006年   294篇
  2005年   263篇
  2004年   262篇
  2003年   230篇
  2002年   235篇
  2001年   187篇
  2000年   215篇
  1999年   173篇
  1998年   83篇
  1997年   59篇
  1996年   57篇
  1995年   65篇
  1994年   52篇
  1993年   53篇
  1992年   119篇
  1991年   113篇
  1990年   109篇
  1989年   121篇
  1988年   108篇
  1987年   118篇
  1986年   119篇
  1985年   104篇
  1984年   105篇
  1983年   82篇
  1982年   57篇
  1981年   67篇
  1979年   77篇
  1978年   46篇
  1977年   53篇
  1974年   54篇
  1972年   62篇
  1970年   53篇
  1969年   45篇
排序方式: 共有8016条查询结果,搜索用时 718 毫秒
1.
A 17‐year‐old boy presented with recurring severe dermatitis of the face of 5‐months duration that resembled impetigo. He had been treated with several courses of antibiotics without improvement. Biopsy showed changes consistent with allergic contact dermatitis and patch testing later revealed sensitization to benzoyl peroxide, which the patient had been using for the treatment of acne vulgaris.  相似文献   
2.
3.
Group A Streptococcus (GAS) predominantly exists as a colonizer of the human oropharynx that occasionally breaches epithelial barriers to cause invasive diseases. Despite the frequency of GAS carriage, few investigations into the contributory molecular mechanisms exist. To this end, we identified a naturally occurring polymorphism in the gene encoding the streptococcal collagen-like protein A (SclA) in GAS carrier strains. All previously sequenced invasive serotype M3 GAS possess a premature stop codon in the sclA gene truncating the protein. The carrier polymorphism is predicted to restore SclA function and was infrequently identified by targeted DNA sequencing in invasive strains of the same serotype. We demonstrate that a strain with the carrier sclA allele expressed a full-length SclA protein, while the strain with the invasive sclA allele expressed a truncated variant. An isoallelic mutant invasive strain with the carrier sclA allele exhibited decreased virulence in a mouse model of invasive disease and decreased multiplication in human blood. Further, the isoallelic invasive strain with the carrier sclA allele persisted in the mouse nasopharynx and had increased adherence to cultured epithelial cells. Repair of the premature stop codon in the invasive sclA allele restored the ability to bind the extracellular matrix proteins laminin and cellular fibronectin. These data demonstrate that a mutation in GAS carrier strains increases adherence and decreases virulence and suggest selection against increased adherence in GAS invasive isolates.  相似文献   
4.
5.
6.
Addison's disease is rarely caused by metastatic cancer. We report a unique case of hypoadrenalism owing to metastatic transitional cell carcinoma of the bladder. The relevant literature is reviewed.  相似文献   
7.
White suckers, collected from lakes containing elevated levels of copper (12 micrograms liter-1) and zinc (250 micrograms liter-1), were evaluated for reproductive performance, growth and survival of the larvae, and tolerance of the larvae to waterborne copper. Fertilization success was not impaired in white suckers from contaminated sites; metal-exposed males performed better than control males in fertilization trials with control eggs. Larvae hatched from eggs collected at contaminated sites and fertilized in clean water were smaller, developed at a slightly increased rate, and exhibited poorer growth and survival than larvae from control sites. Larvae showed significant changes in resistance and tolerance to copper with age. During the period of endogenous nutrition, larvae from eggs taken at contaminated sites showed increased resistance and tolerance to waterborne copper relative to controls. The effect was not seen in larvae at first feeding, at ages older than 4 days after the onset of feeding (25 days posthatch) or in larvae hatched from control eggs fertilized with sperm from males taken at contaminated sites. This study provides evidence for a maternal yolk factor associated with increased tolerance and resistance of larvae to copper.  相似文献   
8.
1. The effects of nedocromil sodium and sodium cromoglycate on bronchoconstriction induced by inhaled sodium metabisulphite have been studied in eight atopic subjects, three of whom had mild asthma. 2. Nedocromil sodium (4 mg, 7.8 X 10(-6) M), sodium cromoglycate (10 mg, 24.1 X 10(-6) M) and matched placebo were administered by identical metered dose inhalers 30 min before a dose-response to sodium metabisulphite (5-100 mg ml-1) was performed. 3. Maximum fall in sGaw after placebo pre-treatment was -43.9 +/- 3.3% baseline (mean +/- s.e. mean). At the same metabisulphite concentration maximum fall in sGaw after sodium cromoglycate was -13.0 +/- 3.6% and after nedocromil sodium was +4.3 +/- 6.8%. Nedocromil sodium prevented any significant fall in sGaw even after higher concentrations of metabisulphite. 4. Both nedocromil sodium, 4 mg, and sodium cromoglycate, 10 mg, inhibited sodium metabisulphite induced bronchoconstriction but nedocromil sodium was significantly more effective. Relative in vivo potency of the two drugs is broadly in line with other in vivo and in vitro studies.  相似文献   
9.
Ventilator-dependent children are surviving longer and increasing in number. This qualitative study was undertaken to describe the impact of a ventilator-dependent child on 10 families and to describe the management styles used by the parents. In five families, the child remained hospitalized due to the disability while in the other five the child primarily lived at home. Three major themes in managing were elicited: barriers, resources, and parenting. Parents believed they should try to normalize their child's experiences, that interactions with health care professionals required negotiation and assertiveness, and that they needed some support person(s) outside of the family.  相似文献   
10.
D M Dixon  A Polak 《Chemotherapy》1987,33(2):129-140
Amphotericin B (Amph B), 5-fluorocytosine (5-FC), ketoconazole (KTZ), fluconazole (FLZ), amorolfine (AMOR) and terbinafine (TER) were tested against 3 agents of central nervous system phaeohyphomycosis in vitro and in life-threatening infections in mice. The fungi studied were Cladosporium bantianum, Dactylaria constricta and Wangiella dermatitidis. The broadest protection against this group of fungi in mice was offered by 5-FC followed by Amph B and FLZ, then KTZ. AMOR and TER were inactive in vivo. The results of in vitro susceptibility testing had no predictive value. In contrast, the data obtained from the mouse models should be useful clinically.  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