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   5862篇
  免费   223篇
  国内免费   17篇
耳鼻咽喉   21篇
儿科学   73篇
妇产科学   152篇
基础医学   654篇
口腔科学   125篇
临床医学   438篇
内科学   1298篇
皮肤病学   64篇
神经病学   433篇
特种医学   411篇
外科学   986篇
综合类   88篇
一般理论   1篇
预防医学   234篇
眼科学   62篇
药学   451篇
  1篇
中国医学   34篇
肿瘤学   576篇
  2023年   39篇
  2022年   53篇
  2021年   100篇
  2020年   45篇
  2019年   67篇
  2018年   70篇
  2017年   62篇
  2016年   62篇
  2015年   90篇
  2014年   101篇
  2013年   141篇
  2012年   235篇
  2011年   252篇
  2010年   159篇
  2009年   119篇
  2008年   229篇
  2007年   288篇
  2006年   244篇
  2005年   236篇
  2004年   201篇
  2003年   226篇
  2002年   257篇
  2001年   219篇
  2000年   246篇
  1999年   225篇
  1998年   130篇
  1997年   88篇
  1996年   93篇
  1995年   66篇
  1994年   67篇
  1993年   47篇
  1992年   147篇
  1991年   146篇
  1990年   139篇
  1989年   138篇
  1988年   135篇
  1987年   117篇
  1986年   109篇
  1985年   109篇
  1984年   65篇
  1983年   55篇
  1981年   30篇
  1980年   28篇
  1979年   56篇
  1975年   33篇
  1973年   27篇
  1972年   34篇
  1971年   26篇
  1969年   34篇
  1968年   28篇
排序方式: 共有6102条查询结果,搜索用时 15 毫秒
81.
82.
The patient was a 74‐year‐old man, who developed progressive cognitive impairment and gait instability. Neuroradiological examination demonstrated a large and predominantly extra‐axial tumor spreading over the bilateral frontal base, indicative of olfactory groove meningioma. The greater part of the resected tumor consisted of a dense, patternless proliferation of large, round or polygonal cells, and compactly fascicular growth of spindle cells. Tumor cells showed markedly anaplastic cytological features. In small areas of the tumor, a typical meningothelial meningioma showing no cellular atypism was found. Both tumor components were closely juxtaposed and no pathological features of an intermediate grade (atypical meningioma) were noted. Shortly after the operation, the patient developed a local recurrence of the tumor and multiple metastases to the cerebrum, bone and skin. Anaplastic meningioma is a rare, highly malignant neoplasm which arises de novo or as a result of the progressive transformation of a low‐grade meningioma. The coexistence of anaplastic and low‐grade components in a single meningeal tumor has been rarely reported. This dimorphic appearance is reminiscent of “dedifferentiation”, a phenomenon infrequently seen in various mesenchymal and salivary gland neoplasms. We think that the term “dedifferentiated meningioma” can be appropriately applied to tumors such as that reported herein.  相似文献   
83.
Background. Insufficiency of renal function and high blood pressure influence each other and eventually result in life-threatening endstage renal disease. It has been proposed that proteinuria per se is a determinant of the progression of chronic kidney disease (CKD). The therapeutic strategy for patients with proteinuric CKD and hypertension should therefore be targeted with a view not merely toward blood pressure reduction but also toward renoprotection. Methods. We examined the effect of the angiotensin (AT)1 receptor antagonist losartan and the calcium channel blocker amlodipine, throughout a period of 12 months, on reduction of blood pressure and renoprotection. This was done by assessing amounts of urinary protein excretion, serum creatinine (SCr), and creatinine clearance (CCr) in patients with hypertension (systolic blood pressure [SBP] 140mmHg or diastolic blood pressure [DBP] 90mmHg) and CKD (male, body weight [BW] 60kg: 1.5 SCr < 3.0mg/dl; female or male BW < 60kg: 1.3 SCr < 3.0mg/dl), manifesting proteinuria of 0.5g or more/day. Losartan was administered once daily at doses of 25 to 100mg/day, and amlodipine was given once daily at 2.5 to 5mg/day. No antihypertensive combination therapy was allowed during the first 3-month period. Results. A 3-month interim analysis revealed that, despite there being no difference in blood pressure between the two groups, there was a significant reduction in 24-h urinary protein excretion in the losartan group (n = 43), but there was no change in the amlodipine group (n = 43). Analysis of stratified subgroups with proteinuria of 2g or more/day and less than 2g/day showed that losartan lowered proteinuria by approximately 24% in both subgroups, while amlodipine lowered proteinuria by 10%, but only in the subgroup of less than 2g/day (NS). SCr and CCr did not change throughout the period of 3 months in either group. No severe or fatal adverse event was experienced in either group during the study period. Conclusions. Losartan appeared to be efficacious for renoprotection in patients with proteinuric CKD and hypertension, with the mechanism being independent of its antihypertensive action.  相似文献   
84.
85.

Background

Endoscopic submucosal dissection (ESD) involves dissection of tumors and manipulation of them in an exposed condition for prolonged periods. A large number of tumor cells are exfoliated into the intestinal lumen after colorectal ESD. The aim of this study was to determine whether lavage volume has an influence on tumor cell clearance after colorectal ESD.

Methods

Twenty patients who underwent colorectal ESD at our hospital between July 2013 and December 2014 were studied. Cytological examination of intraluminal lavage samples associated incremental increases in lavage volume was collected. This prospective study was approved by the ethics committee of our hospital.

Results

No patients had exfoliated tumor cells in their samples before ESD. Four patients (20 %) had exfoliated tumor cells in their samples after lavage with 500 ml, while one patient (5 %) had exfoliated tumor cells after lavage with 1000 or 1500 ml.

Conclusion

Tumor cells are exfoliated into the intestinal lumen by tumor manipulation during colorectal ESD. There seems to be a risk for implantation after ESD, as well as rectal surgery. Sufficient intraluminal lavage of more than 1000 ml may be desirable to remove exfoliated tumor cells after colorectal ESD.
  相似文献   
86.
BACKGROUND: Thoracic paravertebral block (TPVB) is reportedly a useful alternative of general anesthesia (GA) for patients undergoing major breast surgery. To provide surgical anesthesia by TPVB alone, however, demands considerable patient's discomfort during neural block and during surgery. This study was undertaken to investigate if TPVB adds to patient satisfaction when combined with GA for breast cancer surgery. METHODS: In 26 women (ASA I * II) undergoing modified radical mastectomy with axillary dissection, TPVB was performed at T 1 level and 15 ml of 0.5% ropivacaine was injected prior to induction of general anesthesia. After surgery, VAS (visual analogue scale, 0-100 mm) pain scores and postoperative medication were recorded. These data with TPVB were compared with those of 17 patients who had previously undergone similar surgical procedure without TPVB in our hospital. RESULTS: The VAS scores in patients with TPVB were 34 +/- 45 mm (mean +/- SD) on admission to the recovery room and 15 +/- 5 mm next morning. Frequency of postoperative administration of analgesics in patients with TPVB was significantly less than those without TPVB. CONCLUSIONS: Above findings suggest that combined use of TPVB and GA may be a preferable choice of anesthesia for patients undergoing major breast cancer surgery.  相似文献   
87.
塔娜  李思 《中国医疗设备》2020,(3):160-163,170
美国食品和药物管理局(Food and Drug Administration,FDA)经过多年发展和改革,已形成了成熟的上市前监管体系。本文通过对FDA上市批准路径(上市前批准、上市前通告、人道主义用器械豁免)和申报流程进行系统介绍,总结了加强事前沟通、降低产品风险等级和设立实质审查程序三个方面的启示,希望我国监管机构能充分吸收美国FDA对于医疗器械监管的经验和教训,建立适合中国国情的医疗器械监管体系,确保公众用器械安全。  相似文献   
88.
细胞色素P450酶系(CYP450)是人体内参与药物代谢的主要酶,CYP2C19是细胞色素P450酶系中的一种。临床上多种药物在体内代谢时,均需要CYP2C19酶的参与。许多研究显示,CYP2C19酶的活性受CYP2C19基因多态性的影响。本文就CYP2C19基因多态性及其在体内参与几种药物的代谢情况进行分析与总结。  相似文献   
89.
目的评价中心静脉导管留置治疗胸腔积液的疗效。方法257例胸腔积液患者分为两组,治疗组207例,应用胸腔留置中心静脉导管治疗;对照组50例,常规胸穿抽液治疗,观察并比较不同治疗方法的疗效、并发症等指标。结果两组对比多项指标差异有显著性(P〈0.05)。结论采用中心静脉导管治疗胸腔积液可减少胸穿次数、降低反应,提高治愈率。  相似文献   
90.
目的 探讨骨质疏松症中医体质与辨证分型之间的相关性。方法 按照中西医诊断标准,将确诊的骨质疏松症患者进行中医体质分类与中医辨证分型的临床研究,找出其相关性与规律性,并进行总结。 结果 对300例患者进行中医辨证分型发现脾胃气虚证最多,占总病例数的23.00%,其次为肝肾不足证,占22.00%,以后依次为肾阳虚证、肾阴虚证、气血不足证、血瘀证、骨痿证、肝气郁结证、痰湿证、湿热证;在9种体质分类中阴虚质发病率排在第一位,其次为气虚质,以后依次为阳虚质、血瘀质、特禀质、平和质、痰湿质、湿热质与气郁质。结论 提示9种中医体质中阴虚质与气虚质发病率较高, 辨证分型中发病率较高的2个证型是脾胃气虚型与肝肾阴虚型。说明了体质类型与OP发病率有密切的相关性。  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