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   1695290篇
  免费   123709篇
  国内免费   3782篇
耳鼻咽喉   21730篇
儿科学   55634篇
妇产科学   46158篇
基础医学   241215篇
口腔科学   48760篇
临床医学   151310篇
内科学   333523篇
皮肤病学   38651篇
神经病学   131141篇
特种医学   63869篇
外国民族医学   242篇
外科学   257232篇
综合类   38946篇
现状与发展   4篇
一般理论   531篇
预防医学   124229篇
眼科学   40211篇
药学   123610篇
  7篇
中国医学   4476篇
肿瘤学   101302篇
  2021年   12787篇
  2019年   13521篇
  2018年   19952篇
  2017年   15213篇
  2016年   16614篇
  2015年   18962篇
  2014年   26222篇
  2013年   37946篇
  2012年   52741篇
  2011年   55423篇
  2010年   32772篇
  2009年   30694篇
  2008年   51519篇
  2007年   54796篇
  2006年   55254篇
  2005年   52535篇
  2004年   50744篇
  2003年   48150篇
  2002年   46370篇
  2001年   91783篇
  2000年   93605篇
  1999年   76961篇
  1998年   19717篇
  1997年   17269篇
  1996年   17391篇
  1995年   16742篇
  1994年   15289篇
  1993年   14072篇
  1992年   57382篇
  1991年   55271篇
  1990年   52971篇
  1989年   50751篇
  1988年   46134篇
  1987年   44943篇
  1986年   42233篇
  1985年   39991篇
  1984年   29349篇
  1983年   24908篇
  1982年   13898篇
  1979年   25529篇
  1978年   17574篇
  1977年   14906篇
  1976年   13874篇
  1975年   14563篇
  1974年   17631篇
  1973年   16944篇
  1972年   15673篇
  1971年   14453篇
  1970年   13431篇
  1969年   12517篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
951.
Retrosternal dislocations of the clavicle have been reported previously in adults throughout the orthopedic literature. However, in children few cases have been noted in either the pediatric, emergency, or orthopedic literature. The potential for great vessel injury as well as acute airway compromise makes the retrosternal disruption of the sternoclavicular joint a surgical emergency that must be diagnosed quickly. Diagnosis is enhanced by the cephalic tilt view and by computed tomography (CT scan), as planar x-ray and tomography do not always reveal this potentially life-threatening condition. Surgical consultation must be sought acutely; however, management may need to begin prior to definitive repair. Emergency management begins by suspecting the injury, and with immediate airway and circulatory support for the patient.  相似文献   
952.
This study explored coping difficulties experienced by wives of patients with a diagnosis of cancer. Concomitantly, the study explored the ways in which nurses intervened to help these wives. This study was designed as an exploratory study. The qualitative analysis made use of data derived from responses to open-ended questions presented to the respondents by the interview method. The study sample consisted of 40 wives who acknowledged experiencing coping difficulties in meeting the demands of everyday living as a result of their husband's diagnosis of cancer. Respondents were selected randomly from seven eligible representative settings located in the Mid-Atlantic region until the desired sample number was reached. Wives, who encountered the unexpected and uncontrollable situation of having a husband with diagnosed cancer, experienced a multitude of coping difficulties. In addition, wives underwent psychological disorganization, disequilibrium, and emotional imbalance. They attempted to cope with the resulting imbalance by using their habitual problem-solving behavior patterns and experienced difficulty when seeking situational supports. This, in turn, added to their stress. Wives also reported that their children had coping difficulties. Wives identified listening, talking, caring, availability of nurses to patients and patients' spouses, sensitivity, empathy, and honesty as essential helpful nursing behaviors. The study underscored the importance of viewing wives of cancer patients as unique systems in need of therapeutic support, and reaffirmed a view of nursing as the art of understanding the unique needs of individuals who are experiencing coping difficulties. This study also underscored the key role of psychiatric liaison nurses in providing supportive therapeutic interventions to the spouses of cancer patients as well as to the nursing staff.  相似文献   
953.
954.
A variety of nutritional factors influence the bioavailability of calcium and increase a woman's risk of osteoporosis. Eight healthy women completed an 8-week metabolic study designed to investigate the effect of nonalcoholic carbonated beverage consumption on calcium metabolism. Compared with women receiving a control diet, women consuming a diet high in nonalcoholic carbonated beverages demonstrated similar mean serum levels of calcium, ionized calcium, phosphorus, alkaline phosphatase, parathyroid hormone, 1,25-dihydroxyvitamin D3, and osteocalcin. Twenty-four-hour urine volume, creatinine clearance, calcium-creatinine ratio, and phosphorus-creatinine ratio were similar during consumption of the diet high in nonalcoholic carbonated beverages and the control diet. Twenty-four-hour cyclic adenosine monophosphate-creatinine ratio was significantly lower in women consuming the diet high in nonalcoholic carbonated beverage compared with women receiving the control diet (342 +/- 27.4 nmol/mmol vs 409 +/- 22.1 nmol/mmol). Consumption of a diet high in nonalcoholic carbonated beverages on a short-term basis does not appear to affect adversely the serum or urinary markers of calcium metabolism.  相似文献   
955.
956.
There is evidence that leukocyte contaminating red blood cells and platelet concentrates are responsible for refractoriness to platelet transfusions. The efficacy of a cotton-wool filter to remove leukocytes from red blood cells has been documented previously. The present study was designed to evaluate whether the cotton-wool filters can effectively remove leukocytes from platelet concentrates. Sixty pools of random-donor platelets and single-donor plateletpheresis products were filtered through a cotton-wool filter. The efficacy of filtration was determined by measuring the absolute numbers of leukocytes and platelets and subpopulations of mononuclear cells. The average platelet loss was 8% per pool of random platelets and 10% per plateletpheresis product. The average leukocyte removal was 99% from a pool of random platelets and plateletpheresis concentrates collected by CS-3000 and 90% from plateletpheresis concentrates harvested by single-stage COBE/IBM-2997. The filtration removed 100% of granulocytes, 95% of monocytes, 90% of B-lymphocytes, and 85% of T-lymphocytes. We conclude that filtration through a cotton-wool filter is an efficient and cost-effective method for preparation of leukocyte-poor platelets.  相似文献   
957.
958.
S Fukayama  A H Tashjian 《Endocrinology》1989,125(4):1789-1794
We have reported previously that 17 beta-estradiol (E2) inhibits selectively the cAMP response to human (h) PTH and PTH-related protein (hPTHrP), but not to vasoactive intestinal peptide, in human osteoblast-like cells (SaOS-2). We have now extended these studies to investigate the actions of androgens on hPTH-stimulated accumulation of cAMP, and on the roles of new protein synthesis and pertussis toxin (PTox) substrates in the actions of steroid hormones on SaOS-2 cells. Pretreatment with testosterone (T) or 5 alpha-dihydrotestosterone (5 alpha-DHT) for 4-12 h at concentrations of 10(-12) to 10(-8) M inhibited significantly the cAMP response to hPTH by up to 50-70% of control. Like E2, the actions of T and 5 alpha-DHT were selective for hPTH or hPTHrP; there was no inhibition of the stimulatory action of vasoactive intestinal peptide. Two related steroids, 5 beta-DHT and 17 alpha-epitestosterone, did not inhibit the action of hPTH. Pretreatment of cells with cycloheximide, under conditions which inhibited protein synthesis by greater than 90%, reduced the cAMP response to hPTH but did not block the further inhibitory actions of E2, T, or 5 alpha-DHT. Pretreamtent of cells with PTox (100 ng/ml) for 24 h, enhanced the accumulation of cAMP stimulated by hPTH consistent with an action of PTox on Gi; however, the inhibitory actions of E2, T, and 5 alpha-DHT on PTH-stimulated cAMP accumulation were not attenuated by PTox. We conclude that androgens, as well as estrogens, act directly on human bone cells to modulate selectively an early effect of hPTH. The inhibitory actions of these steroid hormones do not appear to depend on new protein synthesis and may not involve a functionally active PTox substrate, presumably Gi.  相似文献   
959.
A 41-year-old woman had acute hepatitis A infection complicated with severe anemia due to selective erythroblastopenia and hemolysis. A mechanism involving a cellular immune reaction is suggested. The hematological complications resolved during steroid treatment. She later developed a transient seropositive arthritis.  相似文献   
960.
To evaluate the use of pelvic ultrasonography in the diagnosis and management of female adolescents with pelvic inflammatory disease (PID), sonograms of 60 patients with PID were compared with those of 40 age-matched controls. Sonograms were evaluated for adnexal volume, adnexal adherence, uterine size, and the presence of cul-de-sac fluid. Eleven (19.3%) of the 57 patients with PID, in whom adequate sonograms were obtained, had tubo-ovarian abscesses; in seven of these patients, the abscesses were diagnosed ultrasonographically before suspected clinically. Even in those patients without tubo-ovarian abscesses, the mean (+/- SD) adnexal volume in the PID group was significantly larger than that of the control group (11.0 +/- 6.8 cm3 vs 5.2 +/- 2.7 cm,3 respectively). Adnexal adherence, uterine size, and the presence of cul-de-sac fluid were not useful in differentiating patients with PID from normal controls. Pelvic ultrasonography can be a useful adjunct in the diagnosis and management of PID in adolescents and may, in some instances, provide diagnoses in the absence of clinical findings.  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