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   1080265篇
  免费   73616篇
  国内免费   1415篇
耳鼻咽喉   15175篇
儿科学   34691篇
妇产科学   28795篇
基础医学   154405篇
口腔科学   29750篇
临床医学   95331篇
内科学   205293篇
皮肤病学   24487篇
神经病学   82099篇
特种医学   43255篇
外国民族医学   202篇
外科学   164291篇
综合类   21729篇
现状与发展   1篇
一般理论   264篇
预防医学   74736篇
眼科学   24600篇
药学   86613篇
  7篇
中国医学   2826篇
肿瘤学   66746篇
  2019年   7850篇
  2018年   11418篇
  2017年   8993篇
  2016年   10184篇
  2015年   11370篇
  2014年   15445篇
  2013年   22380篇
  2012年   30929篇
  2011年   32728篇
  2010年   19211篇
  2009年   18062篇
  2008年   30350篇
  2007年   32502篇
  2006年   33130篇
  2005年   31449篇
  2004年   30177篇
  2003年   28943篇
  2002年   27972篇
  2001年   60227篇
  2000年   61677篇
  1999年   51098篇
  1998年   12549篇
  1997年   11082篇
  1996年   11100篇
  1995年   10382篇
  1994年   9392篇
  1993年   8923篇
  1992年   37939篇
  1991年   36393篇
  1990年   35879篇
  1989年   34419篇
  1988年   30975篇
  1987年   30091篇
  1986年   28307篇
  1985年   26538篇
  1984年   19260篇
  1983年   16164篇
  1982年   8855篇
  1979年   17066篇
  1978年   11434篇
  1977年   10269篇
  1976年   8854篇
  1975年   10103篇
  1974年   11687篇
  1973年   11303篇
  1972年   10792篇
  1971年   10107篇
  1970年   9277篇
  1969年   8968篇
  1968年   7950篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
961.
Approximately 400,000 people die outside US hospitals or chronic care facilities each year. While there has been some recent movement towards initiating procedures for prehospital Do Not Resuscitate (DNR) orders, the most common situation in the US is that emergency medical systems (EMS) personnel are not authorized to pronounce patients dead, but are required to attempt resuscitation with all of the modalities at their disposal in virtually all patients. It is unfair and probably unrealistic for EMS personnel to have to make a determination of the validity of a non-standard prehospital DNR order (for example, a living will or a durable power of attorney for health care). Existing prehospital DNR protocols range from being very restrictive in the scope of patients allowed to participate and in their implementation, to those that are more liberal. Potential benefits of prehospital DNR orders include freeing up vital personnel and material for use by those who would more fully benefit, and alleviating the enormous emotional strain on patients, families, EMS personnel, and hospital medical staffs involved in unwanted resuscitations that only prolong the dying process. Given this, prehospital DNR orders present several legal and moral problems. These include proper patient identification, the nature of the document itself, precautions incorporated into a DNR system to prevent misuse, potential liability for EMS and hospital personnel, and potential errors in implementation. Functioning prehospital DNR systems need to include: 1) specific legislation detailing the circumstances in which such a document could be used, the wording of such a document, and protection from liability for those implementing the document's directives; 2) having the currently valid document immediately available to the EMS personnel or base station doctors; and 3) acceptable means of identifying the patient. Relatively few US jurisdictions as yet have a prehospital DNR order system, although it is an idea whose time is overdue. Society's imperative to use available technology has pushed us into a situation where a technique to save those with a potential to continue a meaningful and wanted existence is being used indiscriminately to prolong the agony of death.  相似文献   
962.
Thyroid function tests were studied in 105 severely disabled children. Fifty-four cases (53%) showed following abnormalities. Serum TSH concentration was increased in 2 cases. Both serum T4 and T3 levels were decreased in 18 cases (17%). Only the serum T4 level was decreased in 25 cases (24%). Only the serum T3 level was decreased in 10 cases (9.5%). Two patients showed primary hypothyroidism. Two patients (monozygotic twins) were suspected to have subclinical hypothalamic-pituitary hypothyroidism caused by septo-optic-dysplasia. Abnormal thyroid functions were caused by anticonvulsants in most patients. The serum T4 level was correlated with the number of anticonvulsants, but not correlated with motor performance (daily activity) or feeding function. Four patients who had low T4 level or low T4 and T3 levels were received L-thyroxine supplementation, but no clinical improvement was observed. The serum TSH concentration was decreased and the TRH test showed hyporeaction in all of these cases. The low T3 level and normal T4 level were not related to anticonvulsant administration. Two of these patients were in poor nutritional condition, resulting in so called low T3 syndrome.  相似文献   
963.
A longitudinal study was conducted to investigate changes in women's mental and physical health around the time of childbirth, and to determine whether health was related to length of maternity leave. Thirty-seven married, employed first-time mothers completed questionnaires during pregnancy, and again at 6 weeks, 3 months, and 6 months postpartum. Results showed that, from pregnancy to the 6th postpartum month, the number of days that mothers were ill because of infections steadily increased. In addition, depressive symptoms for new mothers rose from pregnancy to the 6th week postpartum, and declined thereafter. For women who did not return to work during the period of the study, a significant decline in depressive symptoms was observed from the prenatal period through the 6th postpartum month. These findings demonstrate significant changes in mental and physical health for this group of first-time mothers.  相似文献   
964.
Rats were chronically exposed to poisonous sodium selenite in concentrations 0.5 mg/kg b. m. for 10 weeks. As a result, hydroxyproline contents in blood serum increased, as well as its excretion with urine. It was proved that the procedure enhanced urinary glycosaminoglycane excretion and increased the contents of the protein-related glycosaminoglycanes in the serum. This was accompanied by increased quantities of keratane sulphate and heparin sulphate. The results confirmed that selenium poisonings influenced connective tissues.  相似文献   
965.
The head circumferences of 64 patients with Duchenne muscular dystrophy were measured and found to be greater than those of a normal population. The patients had relative, and in 12 cases, absolute macrocephaly. 47 of the 64 patients underwent intelligence testing and were found to be significantly intellectually impaired, particularly in verbal and language skills. There was no correlation between head circumference or absolute macrocephaly and intellectual performance. The cause of macrocephaly in these patients is unknown and its relevance to the aetiology of intellectual impairment in Duchenne muscular dystrophy is not yet clear.  相似文献   
966.
To compare nerve regeneration in young adult and aging mice, the right sciatic nerves of 6- and 24-month-old mice were crushed at the sciatic notch. Two weeks later, both groups of mice were perfused with an aldehyde solution, and, after additional fixation, the sciatic nerves were processed so that the transverse sections of each nerve subsequently studied by light and electron microscopy included the entire posterior tibial fascicle 5 mm distal to the crush site. The same level was sectioned in unoperated contralateral nerves; these nerves served as controls. Electron micrographs and the Bioquant Image Analysis System IV were used to measure areas of posterior tibial fascicles and count the number of myelinated axons, the number of unmyelinated axons, and their frequency in Schwann cell units. In aging mice, the total number of regenerating myelinated axons was significantly reduced, but totals of regenerating unmyelinated axons in aging and young adults did not differ significantly. In aging mice, the frequency of Schwann cells that contained a single unmyelinated axon was greater, suggesting that before myelination began, Schwann cell ensheathment of axons also was slowed. After axotomy by a crush injury, the area of the posterior tibial fascicle was less than that in young adults and the distal disintegration of myelin sheath remnants also appeared to be retarded. The results indicate that responses of neurons, axons, and Schwann cells could be important in slowing the regeneration of myelinated fibers found in sciatic nerves from aging mice.  相似文献   
967.
This paper reports results of an open prospective study of 26 patients who met DSM-III criteria for panic disorder or agoraphobia with panic attacks. Cognitive-behavioral treatment alone produced clinically and statistically significant improvement in panic symptoms, including both full-blown and limited symptom episodes. In addition, the treatment produced improvement in associated symptoms of phobic avoidance and generalized anxiety. This work provides further preliminary indication of the usefulness of cognitive-behavioral strategies as an alternative to medication in symptom-oriented treatments.  相似文献   
968.
969.
970.
A case of odontoameloblastoma affecting the left mandible is reported. Initially treated by conservative excision due to its small size, the lesion recurred after 18 months and was treated by radical excision and subsequent reconstruction by a rib graft.  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