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   24693篇
  免费   1294篇
  国内免费   173篇
耳鼻咽喉   267篇
儿科学   423篇
妇产科学   334篇
基础医学   3733篇
口腔科学   368篇
临床医学   2213篇
内科学   4954篇
皮肤病学   736篇
神经病学   3045篇
特种医学   1285篇
外科学   3062篇
综合类   184篇
一般理论   6篇
预防医学   1154篇
眼科学   519篇
药学   1941篇
中国医学   37篇
肿瘤学   1899篇
  2023年   92篇
  2022年   77篇
  2021年   303篇
  2020年   263篇
  2019年   314篇
  2018年   420篇
  2017年   328篇
  2016年   467篇
  2015年   519篇
  2014年   721篇
  2013年   925篇
  2012年   1431篇
  2011年   1517篇
  2010年   882篇
  2009年   861篇
  2008年   1560篇
  2007年   1625篇
  2006年   1699篇
  2005年   1723篇
  2004年   1572篇
  2003年   1579篇
  2002年   1515篇
  2001年   368篇
  2000年   366篇
  1999年   410篇
  1998年   382篇
  1997年   311篇
  1996年   246篇
  1995年   196篇
  1994年   220篇
  1993年   178篇
  1992年   147篇
  1991年   162篇
  1990年   157篇
  1989年   156篇
  1988年   141篇
  1987年   107篇
  1986年   109篇
  1985年   115篇
  1984年   116篇
  1983年   98篇
  1982年   96篇
  1981年   106篇
  1980年   79篇
  1979年   81篇
  1978年   68篇
  1977年   78篇
  1976年   76篇
  1974年   81篇
  1973年   54篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
BACKGROUND: Blue dyes used for lymphatic mapping in sentinel lymph node biopsy cause intraoperative anaphylactic reactions in up to 2.7% of patients. With increasing implementation of this technique, the incidence of anaphylaxis to these dyes can be expected to increase. In the literature, the chemically often unrelated and inconsistently designated dyes have been confused, adding to other inconsistencies in the nomenclature. OBJECTIVE: To demonstrate the nomenclature, chemical and physiologic differences, and allergenicity of the various blue dyes used in a medical context. METHODS: We describe a patient with an intraoperative grade IV anaphylactic reaction to isosulfan blue. Immediate-type hypersensitivity was proved by positive skin test reactions and CD63 expression to isosulfan blue and cross-reactivity to patent blue V. RESULTS: A review of the literature clarified the exact nomenclature of the blue dyes and the possible pitfalls of confusing nomenclature in the context of structurally closely related dyes with different allergenic properties. For the detection of type I hypersensitivity, intracutaneous tests are valuable tools. An IgE-mediated mechanism has been shown recently. In most cases, sensitization exists without known previous exposure in a medical context. This may be due to the widespread use of such dyes in objects of everyday life. Preoperative antiallergic medication use does not prevent anaphylactic reactions but apparently reduces their severity. CONCLUSION: For better comparison and precision, the Chemical Abstracts Service number of the respective dye should always be given.  相似文献   
52.
53.
New assisted reproduction technologies provide access to, and require the handling of, genetic material. Such material includes gametes or early-stage embryos. After a selective appraisal of some of the most relevant developments facilitated by the access to germ cells and embryos, this paper identifies some major ethical challenges created by the assisted reproduction technologies, with a special focus on Germany. The rapid progress in medical technology makes it difficult to prohibit or allow assisted reproduction technologies on the basis of such traditional criteria as the protection of human life, medical indications or a preference to adhere to natural processes. Instead, a more open discussion and a flexible application of ethical principles may be more helpful, such as: (i) considering DNA as a biological data file which allows potential access to a person's biography or identity; (ii) reconciling the protection of the early embryo with patients' needs; and (iii) placing both the mother and her embryo at the centre of bioethical and legal considerations, instead of exclusively relying on ethical principles and expert opinions with regard to the embryo alone. To continue the success of assisted reproduction, more attention should be given to the 'lifeworld' philosophy, as some authors have put it.  相似文献   
54.
55.
Prolonged physical exercise is associated with multiple changes in blood hemostasis. Eccentric muscle activation induces microtrauma of skeletal muscles, inducing an inflammatory response. Since there is a link between inflammation and coagulation we speculated that downhill running strongly activates the coagulation system. Thirteen volunteers participated in the Tyrolean Speed Marathon (42,195 m downhill race, 795 m vertical distance). Venous blood was collected 3 days (T1) and 3 h (T2) before the run, within 30 min after finishing (T3) and 1 day thereafter (T4). We measured the following key parameters: creatine kinase, myoglobin, thrombin-antithrombin complex, prothrombin fragment F1 + 2, D-dimer, plasmin-alpha(2)-antiplasmin complexes, tissue-type plasminogen activator antigen, plasminogen-activator-inhibitor-1 antigen and thrombelastography with ROTEM [intrinsic pathway (InTEM) clotting time, clot formation time, maximum clot firmness, alpha angle]. Thrombin generation was evaluated by the Thrombin Dynamic Test and the Technothrombin TGA test. Creatine kinase and myoglobin were elevated at T3 and further increased at T4. Thrombin-antithrombin complex, prothrombin fragment F1 + 2, D-dimer, plasmin-alpha(2)-antiplasmin complexes, tissue-type plasminogen activator antigen and plasminogen-activator-inhibitor-1 antigen were significantly increased at T3. ROTEM analysis exhibited a shortening of InTEM clotting time and clot formation time after the marathon, and an increase in InTEM maximum clot firmness and alpha angle. Changes in TGA were indicative for thrombin generation after the marathon. We demonstrated that a downhill marathon induces an activation of coagulation, as measured by specific parameters for coagulation, ROTEM and thrombin generation assays. These changes were paralleled by an activation of fibrinolysis indicating a preserved hemostatic balance.  相似文献   
56.
57.
58.
59.
OBJECTIVE: Compare the immunological and echocardiographic data of decellularized versus cryopreserved allografts used for RVOT reconstruction during Ross operation. METHODS: From 16/01/03 thru 07/10/03, 20 Ross operations were performed using decellularized (n=11) or cryopreserved (n=9) allografts. Echocardiography was done at discharge, 1, 3, 6 and 12 months and annually thereafter. Samples for determination of antibodies against HLA class I and II were obtained preoperatively and at days 5, 10, 30, 90 and 180 postoperatively. These samples were tested by the ELISA method in LAT-M dishes (unspecific) for identification of circulating antibodies and the results expressed as mean sample values (Is=DO/cutoff). If positive, LAT-E (specific) was performed and PRA levels determined. RESULTS: There was no mortality. Cryopreserved allografts showed marked Is values elevations for class I and II antibodies which started at the first month and remained elevated up to 6 months. In contrast, of the patients receiving decellularized allografts, seven remained negative, two patients had only marginal elevation of class I antibodies and two patients showed abnormal elevations of PRA levels. This response happened earlier than in the cryopreserved group, starting on the 5th postoperative day and has returned to baseline levels in one case. Echocardiography showed mild, but significant, elevation of gradients in cryopreserved valves but none in the decellularized. CONCLUSIONS: Decellularized allografts had normal function up to 18 months and showed important reduction of the immunogenic response when compared to cryopreserved valves.  相似文献   
60.
The elderly account for an ever-increasing proportion of emergency department patients. Demographic data show that the population which is 80 years of age or older will be further increasing in coming years. Due to this fact we sought the reasons of using of the emergency department by elderly patients (≥80 years), admitted by ambulance service, and to analyse the general management of this collective according to a younger comparison group. We used the data from a prospective registry, in which all consecutive patients admitted to the emergency department by ambulance service were included, to process this retrospective analysis. In this registry, diagnosis (in the ICD-10 classification), age, sex, and inpatient/outpatient treatment were documented. In addition further management, intensive care treatment, and outcome during emergency department stay were registered. The patients were stratified by age into two groups (< 80 years; ≥80 years). The observation period lasted from January 1, 2005 to December 31, 2005. During the study 6590 patients were observed of whom 5670 patients (86.0%) were under 80 years (PG<80) and 920 (14.0%) were 80 years of age or older (PG≥80). Comparing inpatient treatment (PG<80: 40.1%; PG≥80: 39.8%) vs outpatient treatment (PG<80: 59.9%; PG≥80: 60.2%) no significant difference between both groups was registered. In comparing the ICD- 10 main diagnosis categories, no relevant difference could be ascertained. By contrast a significantly higher mortality (3.0% vs 1.6%; p≤0.01) in the emergency department was shown within the PG≥80, especially if the diagnosis was myocardial infarction or stroke. The most frequent discharge diagnosis in the PG≥80 was acute myocardial infarction (6.7%). A percutaneous coronary intervention and artificial respiration was less frequently used in the elderly group. Patients beyond 80 years of age nowadays constitute a remarkable proportion of emergency department patients admitted by ambulance service. This group does not differ substantially from younger patients, neither in questions of inpatient or outpatient treatment nor in types of diagnosis. Elderly patients in the emergency department showed a higher mortality. Invasive interventions were less frequently used in this collective in comparison to younger patients. In consideration of the fact that the proportion of elderly will further increase in our population, this analysis may give basis for development of new strategies for the treatment of old patients in emergency departments.  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