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   39950篇
  免费   2981篇
  国内免费   105篇
耳鼻咽喉   368篇
儿科学   1384篇
妇产科学   1095篇
基础医学   4691篇
口腔科学   613篇
临床医学   6719篇
内科学   7558篇
皮肤病学   542篇
神经病学   3666篇
特种医学   864篇
外国民族医学   1篇
外科学   3847篇
综合类   578篇
现状与发展   1篇
一般理论   54篇
预防医学   5322篇
眼科学   553篇
药学   2591篇
中国医学   45篇
肿瘤学   2544篇
  2023年   223篇
  2022年   212篇
  2021年   686篇
  2020年   504篇
  2019年   781篇
  2018年   939篇
  2017年   679篇
  2016年   777篇
  2015年   835篇
  2014年   1187篇
  2013年   1851篇
  2012年   2645篇
  2011年   2843篇
  2010年   1495篇
  2009年   1326篇
  2008年   2496篇
  2007年   2724篇
  2006年   2644篇
  2005年   2576篇
  2004年   2370篇
  2003年   2259篇
  2002年   2170篇
  2001年   518篇
  2000年   472篇
  1999年   514篇
  1998年   487篇
  1997年   392篇
  1996年   330篇
  1995年   381篇
  1994年   300篇
  1993年   303篇
  1992年   326篇
  1991年   334篇
  1990年   306篇
  1989年   285篇
  1988年   276篇
  1987年   264篇
  1986年   279篇
  1985年   274篇
  1984年   265篇
  1983年   227篇
  1982年   235篇
  1981年   221篇
  1980年   191篇
  1979年   177篇
  1978年   149篇
  1977年   131篇
  1976年   116篇
  1974年   119篇
  1973年   110篇
排序方式: 共有10000条查询结果,搜索用时 296 毫秒
61.
62.
63.
64.
The initial poor absorption of the corn oil-based, gel capsule oral formulation of cyclosporin (CyA) greatly limits its use for inception of immunosuppressive therapy. Insufficient drug concentrations during the early post-transplant period predispose to renal allograft rejection. The present study served to compare the time required to achieve therapeutic CyA concentrations after de novo administration of the corn oil-based gel capsule (CyA-GC; n = 11) versus the microemulsion (CyA-ME; n = 11) formulation of CyA. During the 1st month after renal transplantation, patients underwent serial pharmacokinetic profiling from which we obtained observed and dose-corrected values of several parameters. Although patients in neither the CyA-GC nor the CyA-ME group adequately absorbed the drug during days 0–2, from day 3 to 4 patients in the CyA-ME group showed significantly greater absorption than those in the CyA-GC group (P = 0.041). Patients in the CyA-ME group reached the 1st month target average concentration (Cav) values ( ≥ 550 ng/ml) earlier than those in the CyA-GC group and required significantly lower daily CyA doses (P = 0.018). We conclude that therapeutic CyA levels can be achieved more rapidly and with lower doses of the drug after de novo administration of CyA-ME than with CyA-GC. Received: 13 September 1996 Accepted: 7 January 1997  相似文献   
65.
Smoking has recently been identified from epidemiological studies as a possible cause of cataract but the mechanism involved is not known. Therefore, our laboratory has initiated studies aimed at elucidating these mechanisms. Whole bovine lenses were cultured to examine possible effects of cigarette smoke on amino acid uptake and protein synthesis. Cigarette smoke, filtered to remove nicotine and tar which would not reach the eye in vivo, was bubbled through culture medium. Bovine lenses were incubated in this medium in the presence of [14C]-leucine for four days. A significant decrease in uptake of [14C]-leucine and a decrease in protein synthesis were found with smoke treated lenses. This is the first demonstration of an effect of cigarette smoke on the lens. Further work is needed to determine how this metabolic upset is mediated and how it could lead to cataract.  相似文献   
66.
A reductive benzoate pathway is the central conduit for the anaerobic biodegradation of aromatic pollutants and lignin monomers. Benzene ring reduction requires a large input of energy and this metabolic capability has, so far, been reported only in bacteria. To determine the molecular basis for this environmentally important process, we cloned and analyzed genes required for the anaerobic degradation of benzoate and related compounds from the phototrophic bacterium, Rhodopseudomonas palustris. A cluster of 24 genes was identified that includes twelve genes likely to be involved in anaerobic benzoate degradation and additional genes that convert the related compounds 4-hydroxybenzoate and cyclohexanecarboxylate to benzoyl-CoA. Genes encoding benzoyl-CoA reductase, a novel enzyme able to overcome the resonance stability of the aromatic ring, were identified by directed mutagenesis. The gene encoding the ring-cleavage enzyme, 2-ketocyclohexanecarboxyl-CoA hydrolase, was identified by assaying the enzymatic activity of the protein expressed in Escherichia coli. Physiological data and DNA sequence analyses indicate that the benzoate pathway consists of unusual enzymes for ring reduction and cleavage interposed among enzymes homologous to those catalyzing fatty acid degradation. The cloned genes should be useful as probes to identify benzoate degradation genes from other metabolically distinct groups of anaerobic bacteria, such as denitrifying bacteria and sulfate-reducing bacteria.  相似文献   
67.
68.
69.
The ocular findings in three brothers with Bruton's disease are reported. All three boys had purulent conjunctivitis, but the two older brothers also developed marked corneal scarring with visual impairment. Haemophilus influenzae was cultured from conjunctival swabs; it was resistant to neomycin but sensitive to chloramphenicol. Tear analysis showed that the three subjects had normal levels of lysozyme but no detectable IgA.  相似文献   
70.
BACKGROUND: Assessment of inpatient asthma management has generally been limited to urban settings, including Chicago, which is known for its high asthma morbidity and mortality. Previously published data have been based on survey methodology. The Suburban Asthma Consortium (SAC) sought to obtain patient-based data unique to the Chicago suburbs to improve asthma care in those areas. OBJECTIVE: To evaluate current inpatient asthma management based on the 1997 National Asthma Education and Prevention Program (NAEPP). DESIGN: Retrospective chart review of all hospitalized patients 3-65 years bearing asthma-related ICD-9 codes for fiscal year 2002 in community, nonteaching hospitals in Chicago suburbs. RESULTS: Nine hundred two cases were submitted from seven hospitals. The majority ( > or = 75%) received inhaled bronchodilators, systemic steroids, oxygen and pulse oximetry. Antibiotic use (67%), chest radiography (85%), complete blood count (77%), and electrolytes (59%) appeared excessive in view of NAEPP recommendations. Peak flow monitoring (PFM) was recorded on admission in 45% of patients 5 years old and older; 52% had PFM during hospitalization. Thirty-eight percent of patients were taking ICS prior to admission; of those not on ICS, only 12% were newly diagnosed asthmatics. Overall, 51% of patients were discharged with ICS. Patients were more likely to receive ICS at discharge if they had required intensive care (ICU), had been on ICS prior to admission, were referred to an asthma specialist while hospitalized, or were insured. Patients with Medicare/Medicaid (MC/MA) had more repeat emergency visits and hospitalizations, longer lengths of stay, and received less ICS at discharge. Depending on the parameter, 41% or less patients received discharge planning education and were not more likely to have received education if in the ICU. Results ranged significantly between hospitals for most parameters (p < 0.05 or less). CONCLUSION: Study subjects received appropriate acute therapy and oxygen monitoring, but there was a divergence from NAEPP recommendations regarding PFM, ICS use, antibiotics, and laboratory evaluation. Patients receiving MC/MA experienced higher morbidity and received less ICS. Discharge asthma education was suboptimal for most hospitals. Most parameters demonstrated significantly wide practice variations between hospitals. Peak flow monitoring and patient education findings differed significantly from those in survey-conducted studies.  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