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   2027篇
  免费   138篇
  国内免费   14篇
耳鼻咽喉   9篇
儿科学   56篇
妇产科学   49篇
基础医学   368篇
口腔科学   37篇
临床医学   189篇
内科学   413篇
皮肤病学   19篇
神经病学   71篇
特种医学   236篇
外科学   397篇
综合类   14篇
一般理论   1篇
预防医学   96篇
眼科学   2篇
药学   117篇
肿瘤学   105篇
  2021年   21篇
  2020年   15篇
  2019年   20篇
  2018年   31篇
  2017年   26篇
  2016年   22篇
  2015年   28篇
  2014年   29篇
  2013年   51篇
  2012年   67篇
  2011年   73篇
  2010年   39篇
  2009年   54篇
  2008年   69篇
  2007年   75篇
  2006年   69篇
  2005年   76篇
  2004年   65篇
  2003年   53篇
  2002年   52篇
  2001年   57篇
  2000年   57篇
  1999年   53篇
  1998年   32篇
  1997年   41篇
  1996年   43篇
  1995年   35篇
  1994年   33篇
  1993年   22篇
  1992年   53篇
  1991年   48篇
  1990年   66篇
  1989年   70篇
  1988年   65篇
  1987年   69篇
  1986年   63篇
  1985年   76篇
  1984年   43篇
  1983年   39篇
  1982年   41篇
  1981年   34篇
  1980年   23篇
  1979年   27篇
  1978年   28篇
  1977年   20篇
  1976年   15篇
  1975年   10篇
  1974年   15篇
  1973年   14篇
  1967年   11篇
排序方式: 共有2179条查询结果,搜索用时 46 毫秒
61.
62.
63.
Consecutive adult patients (n = 70) referred for investigation of suspected asthma were reinvestigated after 5 years with the same diagnostic procedures (airway symptom score, spirometry, methacholine test) as used at the initial investigation. The same diagnostic criteria for asthma, asthma-like disorder (current asthma-like symptoms but negative asthmatests)and chronicobstructive pulmonary disease (COPD) were used at both visits. At the first visit 39/70 patients (56%) fulfilled the asthma criteria, 21/70 (27%) fulfilled the asthma-like criteria and 5/70 (7%) the COPD criteria. Due to lack of current symptoms 5/70 (7%) could not be classified. 5/70 patients (7%) were smokers, however, in the majority (72%) smoke was not tolerated as it induced asthma-like symptoms. At the investigation, 5 years later, 30/39 patients (76%) still fulfilled the asthma criteria and 12/21 patients (57%) still fulfilled the asthma-like criteria. At the 5-year investigation, 10% of patients in the asthma group now fulfilled the asthma-like criteria and 10% of patients in the asthma-like group fulfilled the asthma criteria. It is concluded that asthma as well an asthma-like syndrome may persist for 5 years or more. It is also concluded thatthe two disorders are closely related as patients in the asthma group over time could move into the diagnostic criteria ofthe asthma-like disorder and vice versa.  相似文献   
64.
Esophageal injury during mediastinoscopy is a rare and easily overlooked complication. In this paper 2 complicated cases, one associated with a pulmonary artery lesion, are reported. Both patients eventually recovered. The principles of management are discussed based on these cases.  相似文献   
65.
A DNA sequence, 552 base pairs in length, encoding the two "virus-associated" (VA) RNAs of adenovirus type 2 is presented. Comparison of the oligonucleotide maps of VA RNAI and VA RNII with the established sequence permits identification of the genes for these RNAs. VA RNAI is 157-160 nucleotides long and VA RNAII 158-163 nucleotides long, depending on the exact length of their heterogeneous 3' end. The genes are separated by a spacer of about 98 nucleotides. The RNAs exhibit scattered regions of primary sequence homology and can adopt secondary structures which resemble each other closely in their configuration and stability. VA RNAII is also capable of assuming a different configuration that is energetically more favorable. The data suggest that the two RNA genes may have arisen by duplication of an ancestral gene and that the folding of the RNA chain may be of importance for the function of VA RNAs. Hypothetical RNA polymerase III recognition sequences and the coding potential of the region are discussed.  相似文献   
66.
Background. Lipolysis of lipoproteins by secretory phospholipase A2 group V (sPLA2‐V) promotes inflammation, lipoprotein aggregation and foam cell formation – all considered as atherogenic mechanisms. Objective. In this study, we compared the susceptibility to sPLA2‐V lipolysis of VLDL and LDL from individuals with type 2 diabetes and the metabolic syndrome (T2D‐MetS) and from healthy controls. Design. VLDL and LDL were isolated from 38 T2D‐MetS subjects and 38 controls, treated pair‐wise. Extent of sPLA2‐V lipolysis was measured as release of nonesterified free fatty acids (NEFA). In a subset of the subjects, lipoprotein composition was determined as a relationship between lipid and apolipoprotein components. Results. Mean paired increase in sPLA2‐V lipolysis after 1 h for T2D‐MetS versus control was 2.0 μmol NEFA l?1 for VLDL (P = 0.004) and 0.75 μmol NEFA l?1 for LDL (P = 0.001). There were also substantial differences in lipoprotein composition between the groups. T2D‐MetS VLDL had higher triglyceride and cholesterol contents than control VLDL. T2D‐MetS LDL was smaller and contained more triglycerides and less cholesterol than control LDL. Both VLDL and LDL from T2D‐MetS subjects also contained more apolipoprotein CIII per particle. Conclusion. VLDL and LDL from T2D‐MetS individuals were more susceptible to sPLA2‐V lipolysis than those from control individuals. This may result in elevated levels of NEFA and lysophosphatidylcholine, both in circulation and in LDL, possibly contributing to the elevated inflammatory state and increased risk of cardiovascular diseases seen in these individuals.  相似文献   
67.
68.
69.
Embury  SH; Gholson  MA; Gillette  P; Rieder  RF 《Blood》1985,65(3):769-771
We have identified a black individual with homozygous sickle cell anemia who is the silent carrier of alpha-thalassemia (genotype - alpha/alpha alpha) due to heterozygosity for the leftward deletion alpha-thal-2 haplotype. This deletion has not been described previously in a black subject and is the only leftward deletion that we have found among 255 alpha-thal-2 chromosomes from sickle cell subjects. Its effects on the clinical, hematologic, biosynthetic, and cellular pathology of sickle cell anemia resemble those reported for the common alpha-thalassemia genotypes of the black population.  相似文献   
70.
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