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   17405篇
  免费   976篇
  国内免费   45篇
耳鼻咽喉   219篇
儿科学   484篇
妇产科学   192篇
基础医学   2164篇
口腔科学   670篇
临床医学   1548篇
内科学   3292篇
皮肤病学   377篇
神经病学   1808篇
特种医学   1420篇
外国民族医学   1篇
外科学   2501篇
综合类   174篇
一般理论   4篇
预防医学   1510篇
眼科学   331篇
药学   816篇
  1篇
中国医学   14篇
肿瘤学   900篇
  2021年   202篇
  2020年   129篇
  2019年   157篇
  2018年   245篇
  2017年   192篇
  2016年   220篇
  2015年   292篇
  2014年   399篇
  2013年   528篇
  2012年   709篇
  2011年   735篇
  2010年   522篇
  2009年   456篇
  2008年   741篇
  2007年   833篇
  2006年   754篇
  2005年   747篇
  2004年   670篇
  2003年   655篇
  2002年   651篇
  2001年   647篇
  2000年   593篇
  1999年   499篇
  1998年   269篇
  1997年   208篇
  1996年   176篇
  1995年   206篇
  1994年   164篇
  1993年   153篇
  1992年   340篇
  1991年   383篇
  1990年   317篇
  1989年   326篇
  1988年   300篇
  1987年   253篇
  1986年   271篇
  1985年   272篇
  1984年   209篇
  1983年   194篇
  1982年   136篇
  1981年   134篇
  1980年   129篇
  1979年   241篇
  1978年   166篇
  1977年   158篇
  1976年   118篇
  1975年   155篇
  1974年   127篇
  1973年   135篇
  1972年   141篇
排序方式: 共有10000条查询结果,搜索用时 21 毫秒
41.
Blepharoplasty and inferior punctal occlusion were performed on 24 consecutive patients with dry eye syndrome. Fifteen patients (62.5%) had symptomatic dry eye syndrome preoperatively and nine patients (37.5%) had asymptomatic dry eye syndrome diagnosed during the preoperative workup (subclinical dry eye syndrome). After surgery, nine patients (37.5%) had improvement of their dry eye syndrome, 10 patients (42%) were unchanged, and two patients (8%) had worsening of their dry eye syndrome. A third patient had worsening of the dry eye syndrome 6 months postoperatively when her puncta reopened. Two patients (8%) had increased irritation only when wearing contact lenses, but in one patient this resolved 6 months after surgery. Thus, although a significant number are improved, a few patients will have worsening of dry eye syndrome after blepharoplasty and inferior punctal occlusion.  相似文献   
42.
Ovalbumin (OVA) is a major allergen (Gal d II) of hen egg white and is often the cause of hypersensitivity reactions to food. Further knowledge of the antigenic and allergenic epitopes of allergens will provide better treatment of this disease. To analyse these epitopes we produced a panel of monoclonal antibodies (mAbs) against native OVA. The initial information about the epitopes was obtained with the binding patterns of these mAbs in IEF-immunoprints and western blots of OVA under reducing and non-reducing conditions. It was possible to demonstrate that the different conformations of OVA exhibit different epitopes, and that there are other epitopes which are shared by each conformation. Seven different, although sometimes overlapping epitopes, could be determined on native OVA; four different epitopes on denaturated non-reduced OVA by means of immunoblots of the intact molecule. The number of epitopes which could be differentiated by the mAbs was increased by the use of peptide blots after CNBr fragmentation of the molecule. IgE binding to different OVA conformations and to CNBr-fragments of OVA was also detectable and appears in the same regions as the reactivity of some mAbs. Western blots of OVA and CNBr-peptides demonstrate that some antigenic/allergenic binding sites seem at least partly to be continuous epitopes. The identification of the CNBr-fragments was performed by a microsequence analysis of blotted CNBr-fragments after a 2-dimensional electrophoresis. IgE was found to bind the two largest CNBr-fragments (residues 41-172 and 301-385), but not the fragment corresponding to residues 173-196. A number of monoclonal antibodies also reacted with the two large fragments, especially with fragment 301-385, and some bind also to shorter peptides, such as fragment 173-196, which were not reactive to patients' IgE. Most of the monoclonal antibodies and patients' IgE bind to the fragments 41-172 and 301-385 in 2D-PAGE blots suggesting that these fragments are involved in an immunogenic structure.  相似文献   
43.
Two techniques are currently available for the creation of low anterior rectal stapled anastomoses. The first technique requires the placement of a pursestring suture at the superior margin of the rectal cuff, which is technically difficult. In the second technique, the rectal cuff is closed with a linear stapler. The circular end-to-end stapler, with the anvil removed, is then passed through an enterotomy in the rectal remnant. We describe an easy and safe method that obviates difficulties during the transanal passage of the stapler and minimizes the risk of injury to the rectum. This method uses an inexpensive and readily available rubber catheter and metal guide.  相似文献   
44.
J T Mail  G J Becker  R W Holden  H Y Yune 《Angiology》1987,38(12):903-911
The postoperative patient may present with one or more of a variety of problems amenable to management by interventional radiologic techniques, which may be curative by themselves or may, in addition, require or allow successful surgical intervention. To optimize patient care, a good working relationship between the vascular surgeon and the interventional radiologist is essential. Consideration should be given to the patient's presenting signs and symptoms, the surgical history with its alteration of anatomy, the results of available noninvasive studies, and knowledge of various therapeutic alternatives. Vascular radiologic interventions include angioplasty, thrombolytic therapy, a combination of both angioplasty and thrombolysis, and newer techniques such as percutaneous valvectomy. In this report, examples of some of the experience at Indiana University are presented. Emphasis is placed on the appropriate approach to the patient.  相似文献   
45.
46.
47.
The Chernoff/Kavlock assay, proposed as a preliminary screen for teratogenic potential, was the subject of a 2-day workshop sponsored by the National Institute for Occupational Safety and Health. Data from three large testing programs were presented, representing tests of 165 chemicals, of which 33 were tested at least twice. Applications of the test in industrial laboratories and product development, hazard identification, and risk assessment were discussed. Workshop participants recognized the assay as one of several valid ways to preliminarily evaluate chemicals with unknown developmental toxicity. Other preliminary tests were also discussed in terms of their relationship to this test, which was seen as having the advantage of providing information on neonatal viability. Other techniques, particularly an abbreviated conventional teratology study, were also recognized as appropriate screens. The preferred test in a particular laboratory will be dependent upon the particular skills and objectives of that laboratory. Standardized protocols were suggested, but flexibility in experimental design was considered necessary, and many variations on the basic test could be appropriate. This preliminary test has been used most often as a single-dose test in mice, but might provide more generally useful data if conducted in rats using two dose levels. Workshop participants viewed the test as highly reliable in correctly identifying developmentally toxic chemicals and suggested that a negative finding in a properly conducted Chernoff/Kavlock test could be a sufficient basis for regulatory agencies to determine that conventional teratology tests in the same species are not warranted.  相似文献   
48.
Platelet aggregability is known to be enhanced and platelet-survival time shortened in smokers when compared with nonsmokers. Up to now it is unknown which of the substances in tobacco smoke are responsible for these effects. To evaluate a possible role of nicotine, rats were chronically treated with the alkaloid (10 mg/kg/day), continuously released from subcutaneously implanted osmotic minipumps. Surprisingly, after 8 weeks, platelet sensitivity toward the aggregating stimulus adenosine 5'-diphosphate (ADP) was markedly reduced. The mean ADP concentration required to induce half the maximum rate of aggregation (EC50) was 0.88 mumol/L in nicotine-treated animals, as compared with 0.67 mumol/L in controls (p less than 0.002). Platelet aggregability remained normal when the rats were treated simultaneously with nicotine and the beta blocker propranolol (3.5 mg/kg/day); for these animals, the mean EC50 for ADP was 0.73 mumol/L. These results are suggestive of a catecholamine-mediated action of nicotine. However, neither the basal levels of cAMP in platelet-rich plasma, nor the cAMP levels attained after stimulation of platelet adenylate cyclase with prostaglandin E1 (PGE1), were affected by 8 weeks of treatment with nicotine or nicotine plus propranolol. No effect on platelet aggregation was observed when the rats were treated with nicotine for only 2 weeks, or when nicotine or nicotine plus cotinine were added to platelet-rich plasma in vitro in concentrations equal to those attained in vivo after 8 weeks. Thus, prolonged application of nicotine in vivo caused an inhibition of ADP-induced rat platelet aggregation presumably mediated by beta-catecholaminergic stimulation of platelets.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   
49.
50.
PURPOSE: New federal regulations allow for office-based treatment of opioid dependent patients with opioid agonist medication (e.g., buprenorphine). We sought to evaluate the literature on office-based physicians' acceptance of this practice. METHODS: We searched the MEDLINE database for original research examining office-based providers' acceptance or satisfaction with office-based treatment. Articles included in the analysis met the following criteria: (1) discussed the treatment of patients with substance abuse disorders, (2) focused on the treatment of opioid dependent patients, (3) discussed treatment with opioid agonist therapy, (4) discussed treatment by office-based physicians, (5) presented original research, and (6) provided data examining physician acceptance or satisfaction. RESULTS: Eight studies met the criteria. Their heterogeneity precluded aggregate analysis. Four of 8 studies revealed that providers had a positive perception concerning the efficacy of opioid agonist treatment, 4/8 indicated that providers believed that opioid dependent patients were more complex than others in their practices, and 3/8 studies indicated the need for additional support services. CONCLUSIONS: There are few studies of provider satisfaction with office-based treatment of opioid dependence. This literature reveals overall provider acceptance of this practice but highlights the need for support services. Further research, designed to identify the barriers to provider satisfaction with office-based opioid agonist therapy, is needed to ensure that these barriers do not limit expansion of this practice.  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