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   2241篇
  免费   130篇
  国内免费   12篇
耳鼻咽喉   4篇
儿科学   130篇
妇产科学   52篇
基础医学   281篇
口腔科学   71篇
临床医学   287篇
内科学   440篇
皮肤病学   159篇
神经病学   92篇
特种医学   258篇
外科学   277篇
综合类   42篇
预防医学   116篇
眼科学   30篇
药学   72篇
  1篇
中国医学   1篇
肿瘤学   70篇
  2021年   15篇
  2020年   14篇
  2019年   25篇
  2018年   34篇
  2017年   33篇
  2016年   21篇
  2015年   44篇
  2014年   51篇
  2013年   60篇
  2012年   65篇
  2011年   76篇
  2010年   69篇
  2009年   82篇
  2008年   76篇
  2007年   65篇
  2006年   63篇
  2005年   69篇
  2004年   50篇
  2003年   67篇
  2002年   56篇
  2001年   53篇
  2000年   44篇
  1999年   51篇
  1998年   93篇
  1997年   100篇
  1996年   99篇
  1995年   66篇
  1994年   61篇
  1993年   59篇
  1992年   48篇
  1991年   52篇
  1990年   34篇
  1989年   68篇
  1988年   57篇
  1987年   77篇
  1986年   50篇
  1985年   57篇
  1984年   36篇
  1983年   26篇
  1982年   26篇
  1981年   25篇
  1980年   12篇
  1979年   21篇
  1978年   11篇
  1977年   17篇
  1976年   13篇
  1975年   12篇
  1974年   8篇
  1973年   13篇
  1966年   7篇
排序方式: 共有2383条查询结果,搜索用时 0 毫秒
31.
REceptors for IgE of rat basophilic leukaemia (RBL) cells, maintained in different laboratories were isolated by means of IgE-Sepharose or IgE and anti-IgE, and characterized by SDS-polyacrylamide gel electrophoresis. All cell lines were found to be associated with a receptor molecule (R) which could be isolated either with IgE-Sepharose or IgE and anti-IgE and a second receptor (H) which could only be isolated with the aid of IgE-Sepharose. The relative amounts of these two molecules, as isolated from surface iodinated cells, varied from the RBL cell line to the other and their apparent molecular weights were not identical on all cell lines. Since comparisons were made on the same gel using receptors isolated from cells labelled with different isotopes of iodine, differences in molecular weight must be considered as being intrinsic and not due to methodological variations. These results provide an explanation why differences were observed among receptors for IgE as characterized in various laboratories. In spite of the fact that the various RBL cell lines originated from the same chemically-induced tumour they have, over the years, undergone changes which are reflected in the receptors for IgE.  相似文献   
32.
Hallam PJ, Mannucci P, Tripodi A, Bevan D, Laursen B, Tengborn L, Wacey A, Cooper DN. Three novel PROC gene lesions causing protein C deficiency. Clin Genet 1998: 54: 231–233. 0 Munksgaard, 1998
Missense mutations. three of them novel (Am210→Val, Asn248→ Ile, Ah355→Val), were found in the protein c ( PROC ) genes of 7 patients with inherited protein C deficiency associated with venous thrombosis. Comparison with the phenotypic effects of mutations in the analogous residues of factor IX causing hdernophilia B and the use of molecular modelling has provided explanations as to how these lesions might alter either the structure, function or secretion of the protein C molecules encoded.  相似文献   
33.
Summary In 1984 10,281 sera were collected in the FRG and examined for antibodies to HTLV-III (LAV) with an enzyme-linked immunosorbent assay and confirmative tests. Of the German AIDS patients 81% have antibodies. Individuals belonging to AIDS risk groups, homosexuals, haemophiliacs and i.v. drug abusers, have antibody frequencies between 25%–72%. The detection of HTLV-III antibodies in blood donours indicates that the virus is being transmitted by blood transfusions.Abbreviations AIDS acquired immunodeficiency syndrome - LAS lymphadenopathy syndrome - ARC AIDS related complex - LAV lymphadenopathy associated virus - HTLV-III human T-lymphotropic virus type III - HBV hepatitis B virus  相似文献   
34.
35.
Hemoglobin Setif produces pseudosickling of red cells in vitro; the nature of the process and the conditions that "trigger" it are unknown. Studies of red cells, hemolysates, purified hemoglobin solutions, and artificial mixtures of Hb A and Setif suggest that pseudosickling is produced by intracellular crystallization of insoluble hemoglobin. Increased tonicity of the suspending medium accentuates the process, probably by causing a rise in intracellular hemoglobin concentration. If precipitates from A/Setif mixtures are analyzed, they always contain Hb A, suggesting an unusual mechanism for the process. Despite the fact that osmolality in the renal medulla is similar to that which produces pseudosickling in vitro, carriers do not have renal dysfunction of the type found in patients with sickle cell disease.  相似文献   
36.
We studied the effect of esophageal acid perfusion on salivation in patients with reflux esophagitis and in normal subjects. Serial 10-min saliva collections were obtained by expectoration during perfusion of the esophagus with water, and then 0.1 N HCl (pH 1.2) for 50 min or 0.01 N HCl (pH 2.1) for 120 min. Within 1-5 min of beginning 0.1 N HCl perfusion, all 8 patients with esophagitis developed heartburn accompanied by an increase in saliva flow. By the time the severity of heartburn required discontinuation of HCl perfusion (10-40 min), saliva flow had increased nearly fourfold. With 0.1 N HCl perfusion, 8 of 10 volunteers developed mild heartburn after 22 +/- 3 min (mean +/- SE), whereas 0.01 N HCl induced heartburn in 6 of 10 volunteers after 57 +/- 12 min of perfusion. Saliva flow increased concurrently with the onset of heartburn and doubled in those volunteers who developed heartburn. Saliva flow did not change in those volunteers who were without heartburn. We conclude that esophageal acid perfusion unaccompanied by heartburn does not affect salivation. However, saliva flow increases concurrently with the onset of heartburn, a phenomenon called "water brash" when clinically evident. The increased saliva flow that accompanies heartburn may act as an endogenous antacid that serves as a protective response to symptomatic gastroesophageal reflux.  相似文献   
37.
Professional responsibilities, tradition, and personal conscience along with legal, philosophical, and religious convictions dictate nursing interventions. Inevitably, these factors embrace life-sustaining therapies; however, in view of complications, prognosis, pain and suffering, and their own views of quality of life, some patients express wishes inconsistent with life-sustaining measures. In other situations, the health care provider as well as the patient may view heroic efforts as more debilitating than resortative. Resolving the conflict while preserving the patient's best interests requires a confrontation with the status of "do-not resuscitate" policies within th e nurse's institution, informed consent, refusal, and competency as the necessary underpinnings for the development of an ethical and legal posture within the profession, with which to approach significant decisions regarding life-sustaining therapies. Literally every hour of every day nurses are immediately and directly involved with resolving ethical dilemmas based upon judgements and interpretations of oral or written orders, patient and family wishes, professional training, and an infinite number of other factors. When clear policies or orders are lacking, the nurse is left with the burden of making a life or death decision. It is imperative that professional nurses assess the administrative, legal, and ethical ramifications of their actions in terms of ethical codes of practice, patients' rights, institutional and personal liability, civil and criminal laws, and private conscience. An understanding of these issues, passive and active euthansia, state and national trends, and uniform legislation can assist in resolutions of the no-code dilemma. Nursing as a profession must strive to develop sound and consistent guidelines and rationale for the scope of practice in ethical dilemmas.  相似文献   
38.
Journal of Prevention - This paper has two goals regarding cultural rigor, defined as privileging cultural ways of knowing and being as a means to achieving health and well-being for future...  相似文献   
39.
Combination high dose rate brachytherapy (HDRB) and external beam radiation therapy is technically and clinically feasible as definitive treatment for localized prostate cancer. We report the first large Australian experience using this technique of radiation dose escalation in 82 patients with intermediate‐ and high‐risk disease. With a median follow up of 3 years (156 weeks), complications were low and overall prostate‐specific antigen progression‐free survival was 91% using the American Society for Therapeutic Radiology and Oncology consensus definition. The delivery of hypofractionated radiation through the HDRB component shortens overall treatment time and is both biologically and logistically advantageous. As a radiation boost strategy, HDRB is easy to learn and could be introduced into most facilities with brachytherapy capability.  相似文献   
40.
Screening for complement deficiency in bacterial meningitis   总被引:1,自引:0,他引:1  
Seventy-seven children with bacterial meningitis were screened for complement deficiency. Both the classical and the alternate pathways were normal in 75 patients. Transiently reduced total haemolytic activity of the classical pathway was documented in a boy with meningococcal meningitis. Total haemolytic activity of both the classical and the alternate pathways were reduced in another patient with pneumococcal meningitis: individual complement components determination indicated predominant activation of the alternate pathway.  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