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   13242篇
  免费   673篇
  国内免费   97篇
耳鼻咽喉   105篇
儿科学   299篇
妇产科学   219篇
基础医学   1546篇
口腔科学   255篇
临床医学   838篇
内科学   3845篇
皮肤病学   208篇
神经病学   881篇
特种医学   471篇
外科学   2388篇
综合类   45篇
预防医学   268篇
眼科学   76篇
药学   805篇
中国医学   28篇
肿瘤学   1735篇
  2023年   105篇
  2022年   202篇
  2021年   384篇
  2020年   223篇
  2019年   292篇
  2018年   333篇
  2017年   260篇
  2016年   311篇
  2015年   352篇
  2014年   442篇
  2013年   470篇
  2012年   912篇
  2011年   913篇
  2010年   550篇
  2009年   466篇
  2008年   785篇
  2007年   840篇
  2006年   851篇
  2005年   816篇
  2004年   848篇
  2003年   813篇
  2002年   846篇
  2001年   172篇
  2000年   107篇
  1999年   177篇
  1998年   196篇
  1997年   161篇
  1996年   140篇
  1995年   103篇
  1994年   97篇
  1993年   76篇
  1992年   91篇
  1991年   60篇
  1990年   75篇
  1989年   60篇
  1988年   61篇
  1987年   37篇
  1986年   46篇
  1985年   40篇
  1984年   38篇
  1983年   26篇
  1982年   24篇
  1981年   19篇
  1980年   22篇
  1979年   26篇
  1978年   16篇
  1977年   20篇
  1976年   12篇
  1973年   11篇
  1971年   13篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
41.
42.
OBJECTIVE: We aimed to determine whether or not the potential distribution of the sympathetic skin response (SSR) on the palm and dorsum of the hand can be described by an equivalent current dipole (ECD) as an SSR source model. METHODS: The SSR of 22 normal subjects were simultaneously obtained from two electrodes placed on the palm and the dorsum of hand, with an indifferent electrode on the thumbnail. We then measured the SSR potential distribution in 10 of the 20 subjects who had responded to stimulation with a clear dorsal SSR. To do this, 18 electrodes were attached to the palm and dorsum of the hand. SSR-evoking stimulation (sound, voice and rapid inspiration) were randomly delivered to the subject at time intervals of more than 1min to minimize the habituation effect. We estimated the ECD from the measured potential distribution. RESULTS AND CONCLUSIONS: The SSR-evoked by stimulation was negative in potential at the palmar sites of all 22 subjects, and was positive in potential at the dorsal sites of the hand in 20 of the 22 subjects. The SSR potential distribution, which was measured in 10 subjects, reached its maximum negative and positive potential near the base of the middle finger on the palm, and near the corresponding site on the dorsum of the hand, respectively. The SSR potential measured on the dorsum of the hand, however, was about 1/3 in amplitude of those on the palmar sites. These results suggest that the SSR source is located on the palm (probably the sweat glands) as confirmed by the estimated ECD (a negative pole on the palm and a positive pole on the dorsum of the hand). We speculate that the SSR may result from the potential difference caused by the Na(+) concentration gradient in the sweat, which results from intracanal reabsorption of Na(+). SIGNIFICANCE: The ECD resulting from the Na(+) concentration gradient within the canal of sweat glands is thought to be the source of the SSR from the negative pole on the palm to the positive pole on the dorsum.  相似文献   
43.
A case of malignant fibrosarcoma originated from pericardium was reported. A 31 year-old female who complained of general fatigue and back pain showed dilated cardiac shadow in chest X-ray. Cardiac blood pool scan with 99mTc-RBC revealed avascular mass in pericardial cavity which push the heart up and left side. It was suspected to be malignant, since the mass had increased 67Ga uptake. CT and MRI also demonstrated that the tissue characterization of the pericardial mass was irregular, and the mass compressed venous return. The large mass originated from pericardium caused the right sided cardiac failure. In 12 years ago, she had a history of operation which resected benign hemangioma in the same space (pericardium). We could suspect the malignant transformation between the two rare pericardial tumors; benign hemangioma and malignant fibrosarcoma.  相似文献   
44.
We investigated the immunohistochemical localization of CD44, hyaluronate receptor, and moesin, of the ezrinradixin-moesin (ERM) family, in osteoclasts after calcitonin adminstration using confocal laser scanning microscopy and transmission electron microscopy to clarify the role of CD44 and moesin in their cytoskeletal organization and cell polarity. We also elucidated the localization of osteopontin (OPN) to confirm its possible role in cell-matrix recognition via CD44. In untreated mice, intense immunoreactivities for CD44 and moesin were detected on the basolateral plasma membrane of osteoclasts. Rhodamine-phalloidin reactivity was seen in a bandlike pattern on the region of contact between osteoclasts and bone and was also detected moderately along their basolateral plasma membrane. At 30 min after calcitonin administration, osteoclasts did not show either clear zones or ruffled borders. The bandlike reactivity of rhodamine-phalloidin in the contact region was diminished, although labeling was seen along osteoclasts. CD44 and moesin were colocalized along their plasma membranes, including the region facing the bone surface. Electron microscopic observation revealed that the microvillus processes in the contacting region with bone surface, as well as the basolateral plasma membrane, showed immunoreactivities to CD44 and moesin. At 60 min, some osteoclasts attached to bone and showed a bandlike pattern of rhodamine-phalloidin. On the other hand, OPN was localized under CD44-positive cytoplasmic processes and the clear zone of osteoclasts. These findings suggest that calcitonin effects on the cell polarity of osteoclasts and the CD44-moesin-actin filament system in osteoclasts plays an imporant role in cell polarity and cell-matrix recognition.  相似文献   
45.
Between January 1985 and September 1994, 21 patients with psychiatric disorders underwent various forms of surgery at our hospital. There were 12 men and 9 women with an average age of 57.6 years. The coexisting psychiatric disorders were schizophrenia in 15 patients, depression in 2, dementia in 2, mental retardation with epilepsy in 1, and Parkinson's disease in 1. All the patients had been receiving neuroleptic medications for a long period. The indications for surgery were: cholelithiasis in 6 patients, acute appendicitis in 4, perforation of the small intestine in 3, incarceration of an inguinal hernia in 2, and esophageal cancer, stomach cancer, bleeding from a gastric ulcer, perforation of a duodenal ulcer, strangulating ileus, and burns in 1 patient each, respectively. All of the patients who underwent elective surgery were given epidural anesthesia with or without general anesthesia. Antipsychotic medications were given until just prior to surgery and recommenced concurrent with the first meal. Abnormal behavior was observed in 11 patients (52.4%) postoperatively, but all the patients were discharged in accordance with recovery from their surgical disorder. Intra- and postoperative hypotension resistant to intravenous catecholamine administration was recognized in 9 patients (42.9%), and this peculiar complication should be borne in mind when patients with psychiatric disorders require surgical management. Presented at the 94th annual meeting of the Japanese Surgical Society, held in Tokyo in March, 1994  相似文献   
46.
OBJECTIVE: To predict accurate morbidity after lung resection using treadmill exercise test. METHODS: A total of 130 patients (108 men and 22 women, with mean age 67.1+/-11.4 years (range, 34-78 years)) of 1129 patients underwent standard lobectomy were performed both treadmill exercise test and spirometry preoperatively. We measured maximum oxygen uptake/body weight (VO2max/BW) and change in arterial blood oxygen pressure from rest to symptom-limited maximum loading (delta aPaO2) and calculated exercise-induced hypoxemia (delta PaO2/delta VO2/BW), and retrospectively compared these parameters for patients with and without complications. RESULTS: There were five patients with severe postoperative complications, including three requiring use of a respirator, two with home oxygen therapy. %Vital capacity, VC (%, 80.2+/-13.2 vs. 92.5+/-20.9, P=0.026), delta PaO2 (Torr, -29.3+/-4.3 vs. -13.2+/-10.8, P=0.0004), VO2max/BW (ml/min/kg, 16.5+/-2.9 vs. 20.6+/-5.1, P=0.018) and delta PaO2/delta VO2/BW (Torr/ml/min/kg, -1.98+/-0.26 vs. -0.57+/-0.47) were significantly associated with worse outcome. All the five patients with complications had delta PaO2/delta VO2/BW<-1.7. CONCLUSIONS: Treadmill exercise testing is a good method for assessment of cardiopulmonary reserve. Limited resection must be performed if delta PaO2/delta VO2/BW is under -1.7.  相似文献   
47.
48.
We report herein the case of a 56-year-old woman who developed secondary Kwashiorkor 9 years after undergoing a total gastrectomy for early gastric cancer. Until she began developing the symptoms of Kwashiorkor, including general fatigue, edema of the face and extremities, anemia, alopecia, and weight loss, she had been leading a normal life post-gastrectomy. Her symptoms were alleviated by total parenteral nutrition (TPN) therapy, but reappeared soon after TPN therapy was discontinued. Therefore, she required several subsequent courses of TPN. In an attempt to permanently resolve the ongoing Kwashiorkor symptoms, reconstructive surgery involving transposition of the jejunum from the previous Graham method to the interposition method was performed 10 years after the initial gastrectomy. After the second operation, her malnutrition was completely alleviated, and she has been in good health for the 8 years since. To our knowledge, there has been no other report of the symptoms of secondary Kwashiorkor after total gastrectomy being alleviated by altering the procedure of reconstruction of the intestinal tract. Thus, we recommend surgical treatment to alter the digestive continuity to a more physiological pathway for selected patients with secondary Kwashiorkor syndrome.  相似文献   
49.
50.
The blocking effects of complement-dependent sperm immobilizingantibodies in the sera of infertile women and monoclonal antispermantibodies against humans and mice on fertilization were investigated.The hemizona assay (HZA) and sperm penetration assay (SPA) wereused to study the inhibitory effects of sera from 22 infertilepatients positive for sperm immobilizing antibodies. Use ofthese tests allowed us to differentiate whether the antibodyblocked sperm—zona pellucida tight binding and/or spermpenetration into the ooplasm. The zona pellucida penetrationassay (ZPA) was also used to study the effects of four monoclonalantibodies (mAbs) on human sperm penetration into the zona pellucida.Seven mAbs against murine spermatozoa were tested for theirinhibitory effects on in-vitro fertilization (IVF) and HZA inmice. Of 22 patient sera with sperm immobilizing antibodies,21 (95.5%) inhibited HZA attachment and penetration, whereasthis did not occur in any of 13 patient sera without these antibodies.However, 19 of 22 (86.4%) patient sera with sperm immobilizingantibodies and eight of 13 (61.5%) patient sera without theseantibodies inhibited the SPA. Two (2C6, 1G12) of four mAbs againsthuman spermatozoa showed strong inhibitory effects in all theassays (HZA, ZPA and SPA). One mAb (3B10) did not inhibit HZAbut blocked ZPA and SPA. Another mAb (H6-3C4) seemed to haveno inhibitory effects on fertilization. Two (Vx 5 and Vx 8)of seven mAbs against murine spermatozoa inhibited IVF in micebut did not block mouse HZA. These findings suggest that antispermantibodies block fertilization at specific stages. Some of themmay inhibit sperm capacitation and thus prevent all processesof fertilization that follow. Some other antibodies may notaffect capacitation and sperm binding to zona pellucida butinhibit the acrosome reaction, followed by the blocking of spermpenetration through zona pellucida and ooplasm.  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