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   6415篇
  免费   446篇
  国内免费   26篇
耳鼻咽喉   35篇
儿科学   198篇
妇产科学   204篇
基础医学   998篇
口腔科学   104篇
临床医学   537篇
内科学   1244篇
皮肤病学   61篇
神经病学   975篇
特种医学   195篇
外科学   815篇
综合类   85篇
一般理论   8篇
预防医学   587篇
眼科学   117篇
药学   308篇
中国医学   5篇
肿瘤学   411篇
  2023年   65篇
  2022年   95篇
  2021年   171篇
  2020年   91篇
  2019年   120篇
  2018年   124篇
  2017年   106篇
  2016年   117篇
  2015年   156篇
  2014年   197篇
  2013年   269篇
  2012年   349篇
  2011年   403篇
  2010年   209篇
  2009年   181篇
  2008年   312篇
  2007年   295篇
  2006年   382篇
  2005年   342篇
  2004年   316篇
  2003年   272篇
  2002年   241篇
  2001年   116篇
  2000年   113篇
  1999年   113篇
  1998年   56篇
  1997年   43篇
  1996年   50篇
  1995年   44篇
  1994年   43篇
  1992年   113篇
  1991年   98篇
  1990年   93篇
  1989年   75篇
  1988年   65篇
  1987年   68篇
  1986年   68篇
  1985年   61篇
  1984年   63篇
  1983年   52篇
  1982年   43篇
  1979年   57篇
  1978年   49篇
  1977年   40篇
  1976年   47篇
  1975年   39篇
  1974年   47篇
  1973年   43篇
  1971年   37篇
  1970年   40篇
排序方式: 共有6887条查询结果,搜索用时 0 毫秒
51.
52.
Are growth centers used as alternative institutions to traditional mental health facilities? Survey methods compared growth centers (N=426) and National Training Laboratories (N=108) participants with clinic patients (N=89). Symptoms, life stress, motivations for participation, process expectations, and various attitudes toward authority, time, and help were assessed prior to participation. Comparisons on degree of psychological distress and avowed motivation indicated that most who attend such activities do so for "psychotherapeutic purposes." Growth centers were found not to be an alternative to traditional psychotherapy, but rather an addition. Eighty percent of the growth center sample had previous or current psychotherapeutic experience. Of the people studied, most go to both rather than to one or the other, and from the perspective of the participants, the institutions do not differ greatly in what they offer, how long the process will take, or what goals will be met.  相似文献   
53.
McLain RF  Lieberman IH 《Spine》2000,25(14):1857-1858
Traditional approaches to thoracic metastases and spinal cord compression have been well worked out and validated in the literature. Anterior decompression is clearly superior to laminectomy; vertebrectomy and reconstruction are indicated for sagittal collapse, instability, and pain; and surgical decompression is necessary in cases of bony impingement. The role of endoscopic and minimally invasive techniques in treatment of metastatic disease is evolving. Dr. Lieberman advocates the use of thoracoscopic anterior approaches as the principal application in these patients, whereas Dr. McLain has found that endoscopic assistance has vastly improved his results with posterolateral decompression. The two authors weigh the relative advantages and disadvantages of these approaches for the selected patient with metastatic thoracic disease.  相似文献   
54.
Objective: To establish tissue inhibitor of metalloproteinase-1 (TIMP-1) concentrations in peritoneal fluid (PF) and sera of women with endometriosis and compare them to disease-free controls.

Design: Prospective randomized study.

Setting: Academic medical center.

Patient(s): Women with laparoscopically documented endometriosis and disease-free women of reproductive age.

Intervention(s): Peritoneal fluid and sera were collected, and some women received gonadotropin-releasing hormone agonist (GnRH-a) therapy for endometriosis.

Main Outcome Measure(s): Peritoneal fluid and sera TIMP-1 concentrations were measured with a specific RIA.

Result(s): The TIMP-1 concentrations were significantly lower in PF and sera of women with endometriosis compared with disease-free women. The GnRH-a therapy restored serum TIMP-1 concentrations.

Conclusion(s): Aberrant expression and localization of TIMP-1 may derange the proteolytic milieu of the peritoneal cavity and contribute to the etiology and underlying physiologic sequelae associated with endometriosis. Measurement of TIMP-1 in serum may aid in diagnosing endometriosis and assist with monitoring treatment efficacy in women with this disease.  相似文献   

55.
目的:评估抗精神病药对迟发性运动障碍(TD)的掩盖,即隐性运动障碍(covert dyskine-sia)状况。方法应用Simpson运动障碍评分表评定TD。入组的69例病人有23例病人完成了减药之前、停药三周后和再服药四个月后的TD评定,69例次检查都给于隶像,并且两个评定者按照录像独立评定TD是否存在,评定TD的一致性良好(ICC=0.75)。结果完成整个调查的23例病人中,减药前TD出现率为  相似文献   
56.
Prodromal symptoms, including disturbances of perceptions, beliefs, cognition, affect, and behavior, are often the first symptoms of schizophrenia. Little is understood about the initial, prodromal stage of schizophrenia, despite the compelling research and clinical need. The development and psychometric properties of a new, time-efficient instrument to characterize and date the initial symptoms of a psychotic illnesses, the Symptom Onset in Schizophrenia (SOS) scale, is described in this paper. The SOS rates the presence and dates the onset of 16 general prodromal, positive, negative, and disorganizational symptoms, as well as a clinician, family, and patient global rating of onset of illness. Inter-rater reliability for the presence of each symptom in 35 patients with schizophrenia, schizoaffective, or schizophreniform disorder was good to excellent, with kappa coefficient >0.7 for 12 items, and >0. 5 for all items. Agreement on symptom duration was good to excellent for individual items (ICC=0.7-1.0) and for global rating of duration of illness (ICC=0.97). Our data indicate that the SOS is a reliable, valid, time-efficient tool useful to retrospectively assess the onset of schizophrenia and related psychotic disorders. Further study is underway to evaluate other psychometric properties of the SOS, including test-retest reliability and predictive validity.  相似文献   
57.
58.
BACKGROUND: Controversy exists regarding the lowest blood hemoglobin concentration that can be safely tolerated. The authors studied healthy resting humans to test the hypothesis that acute isovolemic reduction of blood hemoglobin concentration to 5 g/dl would produce an imbalance in myocardial oxygen supply and demand, resulting in myocardial ischemia. METHODS: Fifty-five conscious healthy human volunteers were studied. Isovolemic removal of aliquots of blood reduced blood hemoglobin concentration from 12.8 +/- 1.2 to 5.2 +/- 0.5 g/dl (mean +/- SD). Removed blood was replaced simultaneously with intravenous fluids to maintain constant isovolemia. Hemodynamics and arterial oxygen content (Cao2) were measured before and after removal of each aliquot of blood. Electrocardiographic (ECG) changes were monitored continuously using a Holter ECG recorder for detection of myocardial ischemia. RESULTS: During hemodilution, transient, reversible ST-segment depression developed in three subjects as seen on the electrocardiogram during hemodilution. These changes occurred at hemoglobin concentrations of 5-7 g/dl while the subjects were asymptomatic. Two of three subjects with ECG changes had significantly higher heart rates than those without ECG changes at the same hemoglobin concentrations. When evaluating the entire study period, the subjects who had ECG ST-segment changes had significantly higher maximum heart rates than those without ECG changes, despite having similar baseline values. CONCLUSION: With acute reduction of hemoglobin concentration to 5 g/dl, ECG ST-segment changes developed in 3 of 55 healthy conscious adults and were suggestive of, but not conclusive for, myocardial ischemia. The higher heart rates that developed during hemodilution may have contributed to the development of an imbalance between myocardial supply and demand resulting in ECG evidence of myocardial ischemia. However, these ECG changes appear to be benign because they were reversible and not accompanied by symptoms.  相似文献   
59.
60.
G E Lieberman  G P Lewis 《Artery》1980,8(4):374-380
The properties of vascular ADP-ase were investigated in microsomal preparations of rabbit aortic cell homogenates. The enzyme was found to have a Km of 9 microM. Its activity was not affected by substrates for other purine nucleoside phosphatases nor by substrates for non-specific phosphatases. However, ATP and beta-gamma-methylene ATP inhibited the enzyme. None of sodium fluoride, ouabain, neuraminidase affected ADP-ase activity whereas oligomycin potentiated the activity. The enzyme had an SH requirement and a divalent cation requirement.  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