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   10468篇
  免费   1036篇
  国内免费   42篇
耳鼻咽喉   32篇
儿科学   462篇
妇产科学   203篇
基础医学   1491篇
口腔科学   395篇
临床医学   1225篇
内科学   1991篇
皮肤病学   187篇
神经病学   1116篇
特种医学   502篇
外科学   1114篇
综合类   213篇
一般理论   10篇
预防医学   1061篇
眼科学   122篇
药学   738篇
中国医学   30篇
肿瘤学   654篇
  2023年   90篇
  2021年   142篇
  2020年   136篇
  2019年   159篇
  2018年   200篇
  2017年   149篇
  2016年   173篇
  2015年   183篇
  2014年   278篇
  2013年   404篇
  2012年   465篇
  2011年   446篇
  2010年   327篇
  2009年   282篇
  2008年   459篇
  2007年   447篇
  2006年   422篇
  2005年   403篇
  2004年   374篇
  2003年   364篇
  2002年   332篇
  2001年   307篇
  2000年   302篇
  1999年   262篇
  1998年   167篇
  1997年   175篇
  1996年   147篇
  1995年   142篇
  1994年   128篇
  1993年   118篇
  1992年   196篇
  1991年   226篇
  1990年   188篇
  1989年   238篇
  1988年   241篇
  1987年   283篇
  1986年   229篇
  1985年   261篇
  1984年   149篇
  1983年   107篇
  1982年   99篇
  1981年   108篇
  1980年   82篇
  1979年   112篇
  1978年   112篇
  1977年   103篇
  1976年   78篇
  1975年   83篇
  1974年   77篇
  1972年   72篇
排序方式: 共有10000条查询结果,搜索用时 10 毫秒
31.
Seventy-nine intestinal contents specimens from 65 turkey flocks were examined for rotavirus and rotaviruslike virus (RVLV) by immune electron microscopy (IEM) and genome electropherotyping. The IEM procedure was slightly more sensitive in detecting these viruses; 7 of 48 specimens (14.6%) positive for virus by IEM were negative by the genome electropherotyping technique. The genome electropherotyping technique more readily differentiated the rotaviruses and RVLVs than did the IEM procedure; 15 of 48 specimens (31%) positive for virus by IEM could not be differentiated into rotavirus of RVLV, whereas only 4 of the 41 specimens (9.7%) positive by genome electropherotyping produced incomplete genome electropherotypes and could not be differentiated. Thirty-one specimens negative by IEM were also negative by genome electropherotyping. Specimens determined to contain only rotavirus by IEM produced only rotavirus genome electropherotypes. Likewise, specimens determined to contain RVLV alone by IEM produced only RVLV genome electropherotypes. Three specimens contained viruses morphologically resembling rotaviruses that were not aggregated by either the anti-turkey rotavirus serum or the anti-turkey RVLV serum and possessed genome electropherotypes distinct from those of the turkey rotavirus and RVLV. These rotaviruses may represent a third, previously unrecognized serogroup of turkey rotaviruses.  相似文献   
32.
33.
34.
This article reviews the pertinent anatomy of each body system involved in the assessment of the head and neck (including the eyes, ears, nose, and throat) and describes the basic elements of the comprehensive health assessment. Frequently encountered chief complaints are discussed. Aspects of the health assessment that will assist the primary care provider in making a differential diagnosis and determining the need for referral are presented. This article is the first of two articles on this topic; the subsequent article will address primary care management of common conditions of the head and neck.  相似文献   
35.
36.
37.
We have monitored the binding of [125I]thienylphencyclidine ([125I]TCP), a novel high affinity radioiodinated ligand that specifically recognizes the NMDA (N-methyl-D-aspartate) receptor in rat brain membranes. [125I]TCP binds with an affinity of about 30 nM, and recognizes a similar number of binding sites to previously employed ligands for this receptor. [125I]TCP binding is characterized by slow association and dissociation rates, and the latter can be modified by the addition of Mg2+ or Zn2+, as previously described for [3H]dizocilpine ([3H]MK801). Other phencyclidine-like ligands displaced [125I]TCP binding with the order of potency dizocilpine greater than thienylphencyclidine greater than ITCP greater than phencyclidine greater than ketamine. The binding of [125I]TCP was also increased by NMDA and glycine-site agonists and inhibited by antagonists of these sites. Surprisingly, however, the polyamines spermidine and spermine did not increase [125I]TCP, even though the polyamine antagonist arcaine was an effective inhibitor of binding. These results show that [125I]TCP is a useful ligand for the NMDA receptor complex that binds to the receptor in a manner that is qualitatively distinct from previously described ligands.  相似文献   
38.
Standard care for patients with renal failure while in an intensive care unit involves traditional hemodialysis or peritoneal dialysis and protein restriction. We present a case of a patient with renal failure supported with continuous arteriovenous hemofiltration with dialysis (CAVH-D) who was given full protein alimentation. Total daily urea clearance was measured from the CAVH-D output. Protein load was 196 +/- 34 g/day while receiving total parenteral nutrition and 164 +/- 30 g/day while receiving enteral alimentation. Serum blood urea nitrogen was controlled between 40 and 75 mg/dL, except during septic episodes. Nitrogen balance was estimated based upon known alimentation protein load and measurable and estimated nitrogenous losses. The patient was potentially in nitrogen equilibrium during most of the dialysis period. The cumulative nitrogen balance was positive by 5.2 g after 67 days of dialysis. Volume of alimentation was 3.49 +/- 0.7 liters/day. With CAVH-D, the renal failure patient can receive full alimentation without volume or protein load limitations. Furthermore, nitrogen balances can be estimated easily while the patient is on CAVH-D.  相似文献   
39.
40.
The States of Mind (SOM) model provided a framework for assessing the balance between self-reported positive and negative affects in a sample of 39 outpatients with major depression and 43 healthy control subjects. The SOM model proposes that healthy functioning is characterized by an optimal balance of positive (P) and negative (N) cognitions or affects (P/(P + N) approximately 0.63), and that psychopathology is marked by deviations from the optimal balance. Research thus far has focused on the functional significance of cognitive rather than affective balance. Within this framework, we hypothesized that patients in untreated episodes of major depression would balance their positive and negative affects at the same level where depressed patients in other studies have balanced their positive and negative cognitions--namely, at P/(P + N) approximately 0.37. Points and confidence interval (CI) estimation procedures yielded results (mean = 0.35, 95% CI = 0.30 - 0.40) consistent with this hypothesis in a sample of 39 depressed male outpatients. Correlational analysis indicated that affect balance is inversely related to symptom severity as measured by self-report (Beck) and clinician-rating (Hamilton) scales.  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