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   215150篇
  免费   15512篇
  国内免费   785篇
耳鼻咽喉   2334篇
儿科学   5578篇
妇产科学   4423篇
基础医学   27782篇
口腔科学   4597篇
临床医学   20443篇
内科学   46556篇
皮肤病学   2819篇
神经病学   20698篇
特种医学   7126篇
外国民族医学   13篇
外科学   33545篇
综合类   3433篇
现状与发展   2篇
一般理论   291篇
预防医学   19308篇
眼科学   4421篇
药学   14650篇
  1篇
中国医学   382篇
肿瘤学   13045篇
  2023年   871篇
  2022年   1468篇
  2021年   3537篇
  2020年   2183篇
  2019年   3482篇
  2018年   4066篇
  2017年   3299篇
  2016年   3537篇
  2015年   4204篇
  2014年   6250篇
  2013年   9026篇
  2012年   13503篇
  2011年   14706篇
  2010年   8287篇
  2009年   7470篇
  2008年   13913篇
  2007年   14749篇
  2006年   14261篇
  2005年   14678篇
  2004年   14094篇
  2003年   13160篇
  2002年   12676篇
  2001年   1925篇
  2000年   1519篇
  1999年   2109篇
  1998年   2874篇
  1997年   2477篇
  1996年   2244篇
  1995年   1986篇
  1994年   1788篇
  1993年   1680篇
  1992年   1250篇
  1991年   1191篇
  1990年   1072篇
  1989年   976篇
  1988年   1037篇
  1987年   1054篇
  1986年   1019篇
  1985年   1108篇
  1984年   1497篇
  1983年   1477篇
  1982年   1829篇
  1981年   1651篇
  1980年   1564篇
  1979年   832篇
  1978年   968篇
  1977年   946篇
  1976年   837篇
  1975年   687篇
  1974年   675篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
91.
92.
Cerebellar hemorrhage is a devastating condition with morbidity and mortality related not only to the etiology of the hemorrhage, but also to the timing of the intervention. Sixteen consecutive pediatric patients with acute cerebellar hemorrhages are presented: 6 had vascular abnormalities, 3 had tumors, and 2 had hemorrhages of unknown etiology. Thirteen of the 16 patients survived with only 1 of the 13 having persistent vegetative state as a neurologic outcome. Six of 8 patients presenting in a moribund condition had good outcomes, and 3 of 4 patients presenting with fixed and dilated pupils also had good outcomes. Thus, in contrast to adults, rapid evaluation by CT scanning, followed by the judicious use of ventricular drainage and prompt surgical treatment, have resulted in favorable outcomes in pediatric patients despite their poor clinical presentations. None of the neonates having cerebellar hemorrhages required surgical intervention; their courses could be followed clinically and with transfontanel ultrasound.Presented as a poster at the 14th Congress of the European Society for Paediatric Neurosurgery, Lyon, France, 21–23 September 1994, and the XXII Annual Meeting of the International Society for Pediatric Neurosurgery, Birmingham, UK, 25–28 September 1994  相似文献   
93.
Summary The ESR spectra produced in irradiated dentin have been studied over a range of incident radiation energies from 50 kVp to 25 MVp. The behavior of the dentin ESR signal strength is similar to that of enamel as a function of the energy of the incident radiation. The magnitude of the dentin ESR signals are, however, up to 10 times smaller than the signals of dental enamel for a given radiation energy. The possible contributions of radiation interaction coefficients, chemical structure, and crystallite size to the differences in ESR spectra are discussed.  相似文献   
94.
95.
A New York court recently struck down state Office of Mental Health regulations governing research involving subjects with impaired decisionmaking capacity. The court held that neither incapacitated adults nor minors could participate in any research protocol that contained a nontherapeutic element, irrespective of possible benefits to the subject or the importance of the knowledge to be gained. Although the decision rested on a technical point of law and dealt only with psychiatric research, the court's holding has significantly broader implications.  相似文献   
96.
Relocation mortality has been cited as an important factor when considering the placement of elderly patients. This study describes the fate of dementia patients relocated to facilitate the move to a new hospital. Some wards were moved as intact units—that is, the patients were kept together and there was little change in the nursing or medical staff. Two other wards were closed, and these patients were dispersed to several existing and new wards and experienced changes of nursing and medical staff. All patients underwent prerelocation and postrelocation orientation programmes. The mortality figures for the total patient group before and after the relocation do not show any statistically significant increase in mortality postrelocation. However, for wards that were closed and where the patients suffered maximum disruption to patient group and nursing staff, there was a significant increase in mortality rates.  相似文献   
97.
A 31-year-old male presented to a neuropsychiatric service for the first time with an erotomatic delusion among other symptoms. He had suffered significant brain damage several times in the past and experienced a recent loss. After extensive evaluation, a trial of haloperidol resulted in some improvement. However, the erotomanic delusion remained unchanged.  相似文献   
98.
Background. The modified Fontan procedure separates the systemic and pulmonary circulations in patients born with a functional single ventricle. Delayed recovery is frequently observed after this procedure. It was our hypothesis that complement activation or cytokine generation may contribute to the pathophysiology of this problem.

Methods. We measured activated complement C3, thromboxane B2, interleukin-6, and tumor necrosis factor- levels by immunoassay in 16 patients undergoing Fontan procedure. Patient plasma samples were obtained preoperatively, on initiation of cardiopulmonary bypass, after administration of protamine, and 1, 4, 8, and 24 hours postoperatively.

Results. There was no early or late mortality in this cohort of patients. Low cardiac output developed in 3 of 16 patients, and pleural effusions developed in 5. The median length of hospital stay was 9 days. Activated complement C3 levels increased from a baseline of 1,486 ± 564 to 4,600 ± 454 ng/mL after cardiopulmonary bypass and administration of protamine, and returned to baseline by 24 hours. The level of interleukin-6 increased from 42 ± 32 to 176 ± 22 pg/mL and at 24 hours remained elevated at 71 ± 15 pg/mL. Neither thromboxane B2 nor tumor necrosis factor- levels increased significantly.

Conclusions. The data demonstrate threefold to fourfold increases in activated complement C3 and interleukin-6, indicating that both humoral and cellular systems are affected. It is our conclusion that complement and cytokine activation may contribute to the delayed recovery observed after Fontan procedure.  相似文献   

99.
A study was made on the causes of unsatisfactory progress in immunization coverage in an area of Tamil Nadu, southern India. The findings led to the appointment of additional community health workers (CHW), improvement in supervision, the enhancement of accessibility to services through an increase in the number of peripheral clinics and the organizing of temporary clinics, and the concentration of effort on underprivileged groups. As a result, immunization coverage was more than doubled. The Community Health and Development Project, a primary health care program serving 68 villages since 1981 with a population of about 80,000 was the site of the study which was conducted by discussions with staff and various members of the community. Issues explored were nonacceptance or dropout reasons, and specific factors affecting immunization coverage. A special effort was made to obtain the views of staff working at the periphery, particularly CHWS. The service area was divided into 4 sectors and the CHWS, auxiliary nurse midwives, community health nurses and other development staff in each were brought together for discussions. Views were also solicited from mothers' clubs and youth groups and in meetings with village leaders. Issues raised were further considered by supervisory staff. Statistical studies and other studies were done to clarify doubtful issues and test hypotheses emerging from the discussion. Poor immunization coverage was linked to inadequate supervision of CHWs, scattered communities (village with houses clustered together had better acceptance rates), difficulty of access to health services (distance factors), and low economic and educational status. In light of the study findings, community health workers were increased from 42 in 1984 to 57 in 1987 to cover all the villages, with modifications in selection method to make the worker acceptable to all sections of the villages; abolishment of the auxiliary nurse midwife and addition of a new category, health aide, to link the CHW and the community health nurse, increase of peripheral clinics from 37 to 75 and holding of more temporary clinics, more efforts to reach all socioeconomic groups and increased health education through film shows, drama, and work with village groups.  相似文献   
100.
Prior to 1975, Stingy Run was a third-order tributary of Kyger Creek, which empties into the Ohio River at Mile 260 (Gallia County, Ohio). Both streams drained strip mine refuse areas and physicochemical measurements indicated acidicmine drainage conditions (e.g., low pH). A depauperate macroinvertebrate community, dominated by a few acid-tolerant taxa, was found in both streams and no fishes were collected. In 1974, Stingy Run was impounded to form a fly ash pond which contains fly ash sluiced from Ohio Power Company's General James M. Gavin coal-fired power plant. Physicochemical and biological sampling during 1975–1986 indicated marked changes in the aquatic ecology of Stingy Run between 1) pre-impoundment and post-impoundment conditions; and 2) effluent pH control treatments after impoundment. Fly ash discharge eliminated acidicmine drainage characteristics in Stingy Run and lower Kyger Creek. After impoundment, net spinning caddisflies and a few dipteran taxa dominated the Stingy Run benthic community, reflecting changes in functional niches likely due to improved habitat and greater food availability. Replacement of acid feed by CO2 injection for effluent pH control and changes in ash pond chemistry occurred concomitant with elimination of a substrate floc; increased species richness and densities of invertebrates were subsequently observed. In Stingy Run, species richness and diversity of fishes increased from 1983 to 1986, reflecting improved water quality and increased benthic production after impoundment. Many of these fishes are opportunistic feeders on drifting insects.  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