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   45243篇
  免费   4962篇
  国内免费   87篇
耳鼻咽喉   632篇
儿科学   1281篇
妇产科学   1260篇
基础医学   7004篇
口腔科学   1063篇
临床医学   6128篇
内科学   8400篇
皮肤病学   594篇
神经病学   3638篇
特种医学   1515篇
外国民族医学   1篇
外科学   6035篇
综合类   926篇
一般理论   29篇
预防医学   4683篇
眼科学   679篇
药学   3670篇
中国医学   62篇
肿瘤学   2692篇
  2021年   616篇
  2020年   407篇
  2019年   701篇
  2018年   804篇
  2017年   580篇
  2016年   719篇
  2015年   755篇
  2014年   1040篇
  2013年   1585篇
  2012年   2105篇
  2011年   2167篇
  2010年   1221篇
  2009年   1097篇
  2008年   1893篇
  2007年   1972篇
  2006年   1923篇
  2005年   1879篇
  2004年   1794篇
  2003年   1742篇
  2002年   1772篇
  2001年   1563篇
  2000年   1592篇
  1999年   1388篇
  1998年   622篇
  1997年   523篇
  1996年   443篇
  1995年   479篇
  1994年   455篇
  1993年   418篇
  1992年   1126篇
  1991年   1059篇
  1990年   1034篇
  1989年   959篇
  1988年   878篇
  1987年   908篇
  1986年   871篇
  1985年   891篇
  1984年   707篇
  1983年   604篇
  1982年   430篇
  1981年   358篇
  1980年   363篇
  1979年   580篇
  1978年   440篇
  1977年   364篇
  1976年   371篇
  1974年   379篇
  1973年   333篇
  1972年   338篇
  1971年   304篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
92.
Corticotropin-releasing factor (CRF) administered intracerebroventricularly produced both a rapid, greater than 50% reduction in splenic natural killer (NK) cytotoxicity and a prolonged elevation in plasma corticosterone levels. In the first 60 minutes following CRF, fivefold increases in corticosterone levels were associated with the suppression of NK activity. However, NK activity returned to control levels at later time points even though elevated plasma corticosterone levels persisted. These data augment the findings that central CRF reduces natural cytotoxicity and establish a time course for the effect in acutely treated rats.  相似文献   
93.
OBJECTIVE. Our objective was to study the imaging findings in patients who had gastric and duodenal obstruction as a long-term complication of cholangiocarcinoma and to determine if the obstruction was associated with radiation therapy. MATERIALS AND METHODS. Between 1973 and 1989, 96 patients had either curative resection or palliative stenting for cholangiocarcinoma involving the hepatic duct bifurcation. Sixty-three (66%) also received adjuvant radiation therapy ranging from 4960 to 7220 rad (cGy). Gastric outlet or duodenal obstruction or both developed subsequently in seven of the 63 patients treated with radiation therapy. Radiographic studies, including upper gastrointestinal series and CT, and medical and surgical records for these seven patients were retrospectively reviewed. RESULTS. Upper gastrointestinal series in the seven patients with obstruction showed narrowing of the lumen, deformity and enlargement of gastric and duodenal mucosal folds, and delayed gastric emptying. CT performed in five of the seven patients showed thickening of the wall of the gastric antrum and small bowel and retained food and fluid within the stomach. All seven patients required gastrojejunostomy; at surgery, dense adhesions and fibrosis were found, and it was not evident whether the obstruction was due to the tumor or to radiation fibrosis. However, because this complication was seen only after radiotherapy, it was presumed to be radiation fibrosis. CONCLUSION. Our experience suggests that radiation therapy increases the risk of postoperative gastric and duodenal obstruction in patients undergoing surgery for cholangiocarcinoma.  相似文献   
94.
Increased dietary NaCl intake increases the responsiveness of central nervous system alpha 2-adrenoceptors which regulate the neural control of renal function in spontaneously hypertensive rats (SHR) but not Wistar-Kyoto (WKY) normotensive rats. The borderline hypertensive rat (BHR) is the first filial offspring of the SHR and the WKY. With increased dietary NaCl intake, the BHR develops hypertension and expresses other characteristics of the hypertensive SHR parent. This investigation sought to determine whether increased dietary NaCl intake in the BHR enhances the responsiveness of central nervous system alpha 2-adrenoceptors. Six weeks of increased dietary NaCl intake (8% versus 1% NaCl) in BHR augmented the depressor, bradycardic, renal sympatho-inhibitory and diuretic responses to intracerebroventricular administration of graded doses (5, 25 and 125 micrograms) of the alpha 2-adrenoceptor agonist, guanabenz. The results suggest that the potential for an increased responsiveness of central nervous system alpha 2-adrenoceptors is genetically transmitted to the BHR by the SHR and may be exposed in the BHR by increased dietary NaCl intake.  相似文献   
95.
We conducted a survey using an unstructured, then a structured, questionnaire to determine the attitudes of 78 postfellowship anaesthetists to the Basic Sciences component of the part I examination for the FRCA. Seventy-two per cent replied. These anaesthetists felt that about 65% of the basic science syllabus was essential to the understanding and practice of everyday anaesthesia, but there was varying opinion as to the importance of specific topics. Cardiovascular, respiratory, central nervous system and renal physiology were all regarded as essential, as was the pharmacology of anaesthetic drugs. Topics regarded as irrelevant included biochemistry, endocrinology, membrane theory and immunology. Paradoxically, there were many topics which anaesthetists regarded as essential but on which they were unable to give a tutorial. There was little difference between the responses of consultants and trainees. This survey may help to identify a core syllabus on which the majority of anaesthetists agree but also suggests that the current syllabus is overloaded with detail that has no place in clinical practice.  相似文献   
96.
97.
Cisplatin is one of the most active single agents in the treatment of advanced cancer of the cervix. The concurrent administration of the nephroprotective agent, sodium thiosulfate, has enabled exploitation of the therapeutic potential of cisplatin. To explore the role of cisplatin dose intensity in the treatment of patients with cancer of the uterine cervix, patients with persistent/recurrent measurable disease were treated with cisplatin at 200 mg/m2 as a 2-hr infusion with sodium thiosulfate given at 3.3 g/m2 1 hr prior to cisplatin and 6.6 g/m2 during the cisplatin infusion. Treatment was repeated monthly. Due to the known cumulative toxicity of cisplatin, treatment beyond two cycles (400 mg/m2) was given only to those patients who had at least demonstrated a PR. Audiologic evaluation was done prior to each cycle of treatment. Eleven patients were entered with a median age of 43 years (range, 25-57), a median KPS of 80% (range, 60-90%), and nine epidermoid and two adenocarcinoma, and all patients had received previous pelvic irradiation. Twenty-eight cycles of treatment were given: 1, five cycles; 3, three cycles; 7, two cycles. No greater than or equal to 3+ hematologic, neurologic, or renal toxicity was demonstrated. Ototoxicity was demonstrated in the mild to moderate hearing loss range (3000-8000 Hz). The greatest threshold shift occurred after the first course of cisplatin. There were three PRs with a maximum duration of 4 months. Due to the significant toxicities encountered, the low response rate, and the limited duration of responses, this trial was closed early to accrual.  相似文献   
98.
This paper explores one facet of a therapeutic relationship with a woman suffering from inoperable cervical cancer. The psychotherapy sessions were conducted in both hospital and the family home and continued on a weekly basis until final termaination immediately prior to the woman's death. Through a ‘suspense structure’ case study narrative, the writer, a nurse psychotherapist, describes the way in which the humanities art and poetry can provide a means through which to understand seemingly incomprehensible feelings related to reviewing past events as a preparation for death. While no explict critique is made of the twin psychoanalytical concept of transference and countertransference, the occurrence is woven into the text. The essential nature of clinical supervision is illustrated in context. The author proposes that engagement in a therapeutic relationship with a dying person presents the worker with parallel struggles manifesting in elementary feelings which require discernment. The central recommendation of this paper is that the rich symbolic language and metaphors, redolent in art and poetry, be harnessed as a potent therapeutic and metaphors, redolent in art and poetry, be harnessed as a potent therapeutic tool. Throughout the discussion, the terms counseling and psychotherapy are used interchangeably.  相似文献   
99.
This is the first of two papers which address aspects of the findings of a large scale study commissioned by the English National Board which set out to examine the impact of Project 2000 on perceptions of the philosophy and practice of nursing. The findings presented here suggest that there have been fundamental shifts in perceptions of the nature and discipline of nursing. Students and diplomates of the course perceive themselves as knowledgeable doers, with their practice well grounded in theory and research. They value the interpersonal skills teaching and place the patient firmly at the centre of care delivery, viewing the patient holistically and being prepared to be fierce patient advocates where necessary. It is difficult to determine the extent to which these shifts can be attributed to the Project 2000 course, although the Project 2000 approach to education appears to be an important factor.  相似文献   
100.
To relate technetium-99m 2-methoxy-isobutyl-isonitrile (99mTc-MIBI) uptake to regional myocardial blood flow (rMBF), 99mTc-MIBI single photon emission tomography (SPET) and H2(15)O positron emission tomography (PET) scans were obtained at rest and after dipyridamole infusion in six patients with single vessel coronary artery disease. 99mTc-MIBI and H2(15)O data sets were created for each segment perfused by the stenotic vessel and for a normal reference area, assigning regions on the SPET tomograms to comparable regions on the PET by similar transaxial image reconstructions. All patients demonstrated post-dipyridamole 99mTc-MIBI perfusion defects in the territories supplied by the stenotic arteries. Resting rMBF in these regions was slightly lower than that in the normal areas (0.82 +/- 0.05 vs 0.90 +/- 0.09 ml/g/min, P = NS). A 43% +/- 14% reduction in 99mTc-MIBI activity in the area at risk was coupled with on average a 60% +/- 9% reduction in post-dipyridamole rMBF compared with control regions (0.98 +/- 0.08 vs 2.52 +/- 0.51 ml/g/min, P < 0.001). Thus, SPET assessment of 99mTc-MIBI uptake tends to underestimate the perfusion contrast between areas with normal and areas with low coronary vasodilatory reserve when compared to PET. However, these findings may still not affect the clinical usefulness of 99mTc-MIBI and more extensive studies are required to confirm these results in the clinical environment.  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