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   5659篇
  免费   409篇
  国内免费   79篇
耳鼻咽喉   54篇
儿科学   167篇
妇产科学   178篇
基础医学   746篇
口腔科学   50篇
临床医学   642篇
内科学   1294篇
皮肤病学   131篇
神经病学   573篇
特种医学   185篇
外科学   858篇
综合类   58篇
一般理论   6篇
预防医学   514篇
眼科学   50篇
药学   409篇
中国医学   10篇
肿瘤学   222篇
  2023年   49篇
  2022年   53篇
  2021年   88篇
  2020年   91篇
  2019年   102篇
  2018年   110篇
  2017年   95篇
  2016年   101篇
  2015年   110篇
  2014年   120篇
  2013年   235篇
  2012年   296篇
  2011年   275篇
  2010年   155篇
  2009年   146篇
  2008年   263篇
  2007年   317篇
  2006年   255篇
  2005年   205篇
  2004年   200篇
  2003年   169篇
  2002年   169篇
  2001年   162篇
  2000年   182篇
  1999年   157篇
  1998年   67篇
  1997年   65篇
  1996年   65篇
  1995年   47篇
  1994年   48篇
  1993年   49篇
  1992年   141篇
  1991年   127篇
  1990年   129篇
  1989年   132篇
  1988年   121篇
  1987年   111篇
  1986年   112篇
  1985年   90篇
  1984年   88篇
  1983年   67篇
  1982年   43篇
  1979年   37篇
  1978年   43篇
  1977年   43篇
  1975年   45篇
  1974年   39篇
  1973年   40篇
  1972年   40篇
  1970年   33篇
排序方式: 共有6147条查询结果,搜索用时 15 毫秒
21.
A case with a fatal outcome caused by infection with Fusobacterium species was seen in a patient recently operated on for heavy snoring with uvulo-palato-pharyngoplasty (UPPP). The mechanism of infection is discussed. It is concluded that a febrile episode seen in patients less than 2 weeks postoperatively should be considered a serious symptom and be treated intensively after thorough examination. © 1994 John Wiley & Sons, Inc.  相似文献   
22.
Erythropoietic protoporphyria (EPP) is a disease of the heme metabolism due to a deficiency of ferrochelatase, leading to accumulation of protoporphyrin (PPIX) in the erythrocyte (red blood cell [RBC]). The major clinical manifestation in EPP is photosensitivity; however, in a small number of patients liver failure is a significant complication and liver transplantation is the only treatment option. Damage to both abdominal skin and organs occurs when exposed to operating light; however, this problem can be ameliorated by the use of filters that block the transmission of light with wavelength below 470 nm. A more unusual but very serious complication postoperatively is severe motor neuropathy, with few or no known acute available precautions. An effective treatment option is needed to manage EPP crises and to prevent complications after liver transplantation. We successfully treated a patient with EPP-induced liver failure with the molecular adsorbents recirculating system (MARS) and Prometheus in independent sessions. Following treatment with MARS we found a 9.1% reduction of the RBC-PPIX concentration and a 5.9% reduction after treatment with the Prometheus system. Plasmapheresis made a reduction in RBC-PPIX concentration of 0.8%. Following treatment sessions with MARS and Prometheus, the clinical condition was markedly improved and orthotopic liver transplantation was performed without further complications. In conclusion, extracorporeal therapy with MARS or Prometheus seems to be efficient in reducing RBC-PPIX concentration in comparison to plasma exchange.  相似文献   
23.
Brain function requires oxygen and maintenance of brain capillary oxygenation is important. We evaluated how faithfully frontal lobe near-infrared spectroscopy (NIRS) follows haemoglobin saturation (SCap) and how calculated mitochondrial oxygen tension (PMitoO2) influences motor performance. Twelve healthy subjects (20 to 29 years), supine and seated, inhaled O2 air-mixtures (10% to 100%) with and without added 5% carbon dioxide and during hyperventilation. Two measures of frontal lobe oxygenation by NIRS (NIRO-200 and INVOS) were compared with capillary oxygen saturation (SCap) as calculated from the O2 content of brachial arterial and right internal jugular venous blood. At control SCap (78%+/-4%; mean+/-s.d.) was halfway between the arterial (98%+/-1%) and jugular venous oxygenation (SvO2; 61%+/-6%). Both NIRS devices monitored SCap (P<0.001) within approximately 5% as SvO2 increased from 39%+/-5% to 79%+/-7% with an increase in the transcranial ultrasound Doppler determined middle cerebral artery flow velocity from 29+/-8 to 65+/-15 cm/sec. When SCap fell below approximately 70% with reduced flow and inspired oxygen tension, PMitoO2 decreased (P<0.001) and brain lactate release increased concomitantly (P<0.001). Handgrip strength correlated with the measured (NIRS) and calculated capillary oxygenation values as well as with PMitoO2 (r>0.74; P<0.05). These results show that NIRS is an adequate cerebral capillary-oxygenation-level-dependent (COLD) measure during manipulation of cerebral blood flow or inspired oxygen tension, or both, and suggest that motor performance correlates with the frontal lobe COLD signal.  相似文献   
24.
Background: The authors explored the database of the first International Study of Postoperative Cognitive Dysfunction study to specify the domains of cognitive function that were most vulnerable and to determine the pattern of deterioration in patients with preoperative cognitive impairment.

Methods: One thousand two hundred eighteen patients were included in the first International Study of Postoperative Cognitive Dysfunction, where neuropsychological testing was performed at entry to the study, at 1 week, and at 3 months after surgery. The authors' analyses determined the extent to which seven neuropsychological measures changed after surgery with focus on the relation with preoperative cognitive impairment, defined as a preoperative score 1.5 SD below healthy controls in the memory test.

Results: Preoperative cognitive impairment was found in 74 patients at baseline. At 1 week, cognitive deterioration was seen in all tests, but in particular in the Letter Digit Coding and the time of the Stroop interference test, with 14% and 16% of the total sample (n = 1,016) exceeding 2 SD, respectively. At 3 months, deterioration was more uniform. Significantly fewer in the preoperative cognitive impairment group had deterioration in the memory test, both at 1 week and at 3 months, with no patient displaying a deterioration exceeding 2 SD.  相似文献   

25.

Objectives:  

To examine the extent to which school climate and school pressure could predict other aspects of adolescents’ lives, most particularly their emotional health and bullying. Furthermore, the study sought to investigate if these relationships were consistent across countries.  相似文献   
26.
Abstract: Blast cells derived from peripheral blood of patients with acute myelogenous leukaemia (AML) were cultured in vitro and interleukin 1 receptor antagonist (IL1RA) concentrations determined in culture supernatants. AML blasts derived from patients classified as AML-M4 and AML-M5 subtype showed an increased release of IL1RA. IL1α and IL1β caused a similar increase in AML blast release of IL1RA, and addition of anti-ILl antibodies decreased IL1RA release. IL1RA release from AML blasts was also increased by stem cell factor, tumour necrosis factor α (TNFα), granulocyte-macrophage colony-stimulating factor and macrophage colony-stimulating factor, whereas interleukin 3, interleukin 6, leukaemia inhibitory factor and granulocyte colony- stimulating factor did not significantly alter IL1RA release. When investigating IL1RA serum levels, serum concentrations were decreased in acute leukaemia patients with chemotherapy-induced cytopenia compared with healthy controls. Serum levels of both IL1RA as well as IL1β and soluble TNFα receptors increased when the leucopenic patients developed complicating bacterial infections.  相似文献   
27.
28.
29.
Introduction : Hypertrophic scar is a devastating sequel to burns and other tangential skin injuries. It follows deep dermal injuries and does not occur after superficial injuries. Nitric oxide (NO) plays many important roles in wound healing from inflammation to scar remodeling. Studies have shown that expression of nitric oxide synthase and nitric oxide production are decreased in human hypertrophic scar. However little is known about NO involvement in the early stages of hypertrophic scarring, because of the lack of an animal model. It was recently reported that the female red Duroc pig (FRDP) makes thick scar, which is similar to human hypertrophic scar. We hypothesized that NO production in wounds on the female, red Duroc pig is similar to that of human hypertrophic scar and that NO involvement in deep wounds is different from that in superficial wounds. Methods : Superficial (0.015” to 0.030”) and deep (0.045” to 0.060”) wounds were created on the backs of four FRDPs. Biopsies were collected at weeks 1.5, 4, 8 and 21 post wounding including samples of uninjured skin. Nitric oxide levels were measured with the Griess reaction assay and normalized with tissue protein level. Results : Superficial wounds healed with an invisible scar whereas the deep wounds healed with scar resembling mild hypertrophic scar. The thickness of the scars from the deep wounds was significantly greater than uninjured skin and healed superficial wounds (p < 0.01). NO levels were increased at 1.5 weeks in deep wounds compared to superficial wounds and uninjured skin (p < 0.05). At 8 weeks, NO levels in deep wounds had returned to the level of uninjured tissue and superficial wounds. By 21 weeks, NO levels had decreased significantly when compared to superficial wounds (p < 0.01). There were no differences in NO levels between uninjured skin and superficial wounds at any time point (p > 0.05). Conclusions : NO production is similar in late, deep wounds on the female, red Duroc pig to that reported in the literature for human hypertrophic scar further validating this animal model. NO production is quite different after deep wounds as compared to superficial wounds in the FRDP. Early elevation in nitric oxide production might account for excessive inflammation in deep wounds that become thick scars in the FRDP. Nitric oxide regulators and effects at early stages of scar formation should be elucidated further and the FRDP appears to be a useful model.  相似文献   
30.
Examination is a cornerstone in the manual procedures leading to mobilisation/manipulation of the low back. The observer variation of the more specific segmental tests remains to be investigated. Two skilled specialists in manual medicine examined the segmental changes in the lumbar spine. The patients were unknown to the examiners and no information of the case history was given. All test results were recorded by an observer present in the room who ensured that no conversation was allowed during the examination. The primary outcome measures were the kappa values for each test. The matching was defined as acceptable (acc) within two neighbouring levels and perfect (per) on the same level. Intra-observer variation (tested in 33 patients and 10 subjects without low-back pain): The agreement between first and second segmental diagnosis examination was 70% (per) and 82% (per + acc). Kappa values were: segmental diagnosis 0.60 (per) and 0.70 (per + acc), multifidus test 0.51 (per) and 0.60 (per + acc), sideflexion 0.57 (per) and 0.69 (per + acc), and ventral flexion 0.31 (per) and 0.45 (per + acc). Inter-observer variation (tested in 60 patients): The agreement for segmental diagnosis between the examiner A and B was 42% (per) and 75% (per + acc). Kappa values were: segmental diagnosis 0.21 (per) and 0.57 (acc), multifidus test 0.12 (per) and 0.48 (acc), sideflexion 0.22 (per) and 0.45 (acc), and ventralflexion 0.22 (per) and 0.44 (acc). By manual tests, skilled examiners seem to be able to diagnose segmental dysfunctions in the low back. The clinical implication of these dysfunctions remains to be clarified.  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