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   5616篇
  免费   493篇
  国内免费   92篇
耳鼻咽喉   128篇
儿科学   382篇
妇产科学   123篇
基础医学   874篇
口腔科学   438篇
临床医学   430篇
内科学   1448篇
皮肤病学   46篇
神经病学   36篇
特种医学   182篇
外国民族医学   3篇
外科学   786篇
综合类   425篇
现状与发展   2篇
预防医学   181篇
眼科学   77篇
药学   206篇
中国医学   51篇
肿瘤学   383篇
  2024年   16篇
  2023年   66篇
  2022年   135篇
  2021年   181篇
  2020年   213篇
  2019年   245篇
  2018年   225篇
  2017年   215篇
  2016年   209篇
  2015年   205篇
  2014年   293篇
  2013年   381篇
  2012年   226篇
  2011年   271篇
  2010年   257篇
  2009年   265篇
  2008年   260篇
  2007年   274篇
  2006年   271篇
  2005年   232篇
  2004年   200篇
  2003年   158篇
  2002年   147篇
  2001年   147篇
  2000年   104篇
  1999年   101篇
  1998年   108篇
  1997年   111篇
  1996年   105篇
  1995年   66篇
  1994年   65篇
  1993年   55篇
  1992年   41篇
  1991年   48篇
  1990年   37篇
  1989年   24篇
  1988年   33篇
  1987年   30篇
  1986年   35篇
  1985年   21篇
  1984年   27篇
  1983年   17篇
  1982年   19篇
  1981年   13篇
  1980年   14篇
  1979年   4篇
  1978年   8篇
  1977年   10篇
  1976年   4篇
  1973年   3篇
排序方式: 共有6201条查询结果,搜索用时 15 毫秒
71.
柴胡疏肝散具有疏肝理气、活血止痛之效果,可用于肝气郁结、胁肋疼痛、往来寒热等病症,许芝银教授根据多年临床经验,灵活运用其改方治疗证型相符的甲状腺、乳腺疾病,体现了中医学“异病同治”的特点,在临床上取得了良好的疗效。现列举许教授运用柴胡疏肝散治疗结节性甲状腺肿、Graves病、乳腺囊性增生验案3则,为临床上使用柴胡疏肝散治疗甲状腺、乳腺疾病提供参考。  相似文献   
72.
We report a case of a 29 year old male who at age 25, developed a pulmonary abscess in the left lower lobe. A left lower lobectomy was performed following two recurrences on antibiotic treatment. The result of histopathological examination confirmed congenital cystic adenomatoid malformation (CCAM), a congenital disease characterized by multiple cysts resulting from adenomatous hyperplasia of the bronchial epithelia. In many cases, respiratory distress occurs during the neonatal period, and in about 80–85% of patients, CCAM is diagnosed before the age of two years due to respiratory infection. CCAM which was diagnosed in adulthood is very rare.  相似文献   
73.
目的:分析胎儿颌面颈部先天性囊性肿块的 MRI特点,提高产前胎儿影像诊断水平。方法:回顾性分析16例胎儿颌面颈部囊性肿块的 MRI表现,并与产后手术病理或尸检结果对照。结果:12例淋巴管畸形多表现为多房状,多数分布于颈后部,呈蔓延性生长,可跨中线,合并出血时囊内可见出血信号及液液平面。3例鳃裂囊肿均呈单囊,分布于颈前胸锁乳突肌前方,T1 WI呈低或稍低信号。1例鞍区的脑膜膨出疝入口腔内形成一巨大囊肿,与脑脊液信号一致。结论:MRI可以清晰显示胎儿颌面颈部先天性囊性肿块的轮廓、部位、形态、信号特点,有助于不同囊性肿块的鉴别。MRI 还能很好地显示气道有无压迫,为产时胎儿宫外处理提供更多信息。  相似文献   
74.
目的:探讨人涎晾昧样囊性癌嗜神经侵袭在大体形态学上的发生发展过程。方法:将人涎腺腺样囊性癌肺高转移癌Acc—M细胞系接种于5只裸鼠双侧臀部肌肉内,从荷瘤长出开始,解剖出荷瘤与神经以观察它们的关系,以后每隔5天在同一部位解剖一次,连续观察1个月,同时观察和对比各裸鼠神经受肿瘤侵袭后相应肢体的功能变化。结果:腺样囊性癌发生嗜神经侵袭的方式是,瘤组织细胞以神经干为中心以边生长边包裹边侵袭的方式进行的。结论:腺样囊性癌嗜神经侵袭是以一种特殊的方式进行的,这对临床诊断与治疗具有良好的指导意义。  相似文献   
75.
Prenatal forms of autosomal dominant polycystic kidney disease (ADPKD) are rare but can be recurrent in some families, suggesting a common genetic modifying background. Few patients have been reported carrying, in addition to the familial mutation, variation(s) in polycystic kidney disease 1 (PKD1) or HNF1 homeobox B (HNF1B), inherited from the unaffected parent, or biallelic polycystic kidney and hepatic disease 1 (PKHD1) mutations. To assess the frequency of additional variations in PKD1, PKD2, HNF1B, and PKHD1 associated with the familial PKD mutation in early ADPKD, these four genes were screened in 42 patients with early ADPKD in 41 families. Two patients were associated with de novo PKD1 mutations. Forty patients occurred in 39 families with known ADPKD and were associated with PKD1 mutation in 36 families and with PKD2 mutation in two families (no mutation identified in one family). Additional PKD variation(s) (inherited from the unaffected parent when tested) were identified in 15 of 42 patients (37.2%), whereas these variations were observed in 25 of 174 (14.4%, P=0.001) patients with adult ADPKD. No HNF1B variations or PKHD1 biallelic mutations were identified. These results suggest that, at least in some patients, the severity of the cystic disease is inversely correlated with the level of polycystin 1 function.  相似文献   
76.
The differential diagnosis between benign and malignant pancreatic cystic lesions may be very difficult. We recently found that F-18-.uorodeoxyglucose positron emission tomography (18-FDG PET) was useful for the preoperative work-up of pancreatic cystic lesions. This study was undertaken to confirm these results. From February 2000 to July 2003, 50 patients with a pancreatic cystic lesion were prospectively investigated with 18-FDG PET in addition to helical computed tomography (CT) and, in some instances, magnetic resonance imaging (MRI). The validation of diagnosis was based on pathologic findings after surgery (n = 31), percutaneous biopsy (n = 4), and according to follow-up in 15 patients. The 18-FDG PET was analyzed visually and semiquantitatively using the standard uptake value (SUV). The accuracy of FDG PET and CT was determined for preoperative diagnosis of malignant cystic lesions. Seventeen patients had malignant cystic lesions. Sixteen (94%) showed increased 18-FDG uptake (SUV >2.5), including two patients with carcinoma in situ. Eleven patients (65%) were correctly identified as having malignancy by CT. Thirty-three patients had benign tumors: two patients showed increased 18-FDG uptake, and four patients showed CT findings of malignancy. Sensitivity, specificity, positive and negative predictive value, and accuracy of 18-FDG PET and CT in detecting malignant tumors were 94%, 94%, 89%, 97%, and 94% and 65%, 88%, 73%, 83%, and 80%, respectively. 18-FDG PET is accurate in identifying malignant pancreatic cystic lesions and should be used in combination with CT in the preoperative evaluation of patients with pancreatic cystic lesions. A negative result with 18-FDG PET may avoid unnecessary operation in asymptomatic or high-risk patients. Presented at the Forty-Fifth Annual Meeting of The Society for Surgery of the Alimentary Tract, New Orleans, Louisiana, May 15–19, 2004 (oral presentation). This study was supported by the Ministero Università e Ricerca Scientifica (Cofin 2001068593-001), Rome, Italy.  相似文献   
77.
Objective To discuss the diagnosis and outcome of multilocular cystic renal cell car-cinoma. Methods The clinic data of 1 case of multilocular cystic renal cell carcinoma were reviewed with its clinical manifestation, imaging, pathology and therapy in our hospital. The male patient aged 49 was incidentally found to have a right renal tumor. The CT scan showed a multiloeular cystic tumor in the low pole of the right kidney with a clear outline. The thin septa were found in the tumor, which were enhanced in the enhancement CT scan. The enhancement MRI showed the cystic wall was en-hanced. Results The patient received a partial nephrectomy as his treatment. The pathological char-acteristics were as following: the multilocular cystic tumor was about 3 cm×2 cm×2 cm with clear serosity in it. The cystic wall was smooth with the width of 0.1-0.2 cm. Most of the cystic cavities were covered by monostratified or stratified cubic clear cells, and some were covered by squamous epi-thelium or no epithelium at all. The septum was composed of collagen fiber, and clear cells were found in it. The clear cells form small collections but do not form expansile nodules. The final pathological diagnosis was multilocular cystic renal cell carcinoma. The follow-up was 20 months, without local re-currence or distant metastasis was found. Conclusions Multilocular cystic renal cell carcinoma (MCRCC) is a rare variant of renal cell carcinoma with a good prognosis. MCRCC is an uncommon tumor of the kidney composed of multiple cysts with clear cells in the septa indistinguishable from grade I renal cell carcinoma. Most patients are asymptomatie and the tumors are discovered inciden-tally. The preoperative diagnosis of MCRCC immediately depends on imaging studies. Pathology is the key to diagnosis.  相似文献   
78.
There is a considerable variation in the histologic subtype of epithelial malignancies among carcinoma ex pleomorphic adenomas (CXPA) and virtually any known carcinoma entity can develop. To our knowledge, adenoid cystic carcinoma (AdCC) ex PA is quite rare despite the fact that de novo AdCC is the fourth most common salivary gland malignancy. We describe a new case of AdCC ex PA in the parotid gland of a 62 year-old woman. In our patient, there was a short interval of time between parotidectomy and local recurrence and rapid development of distant metastases. Although most of the reported cases are considered low-grade, evidence is presented here that AdCC can take the form of a high-grade malignancy in PA.  相似文献   
79.
Histologic grade is a significant predictor of outcome in salivary gland carcinomas. However, the sheer variety of tumor type and the rarity of these tumors pose challenges to devising highly predictive grading schemes. As our knowledge base has evolved, it is clear that carcinoma ex pleomorphic adenoma is not automatically a high grade tumor as is traditionally suggested. These tumors should be further qualified as to type/grade of carcinoma and extent, since intracapsular and minimally invasive carcinomas ex pleomorphic adenoma behave favorably. The two carcinoma types for which grading schemes are common include adenoid cystic carcinoma and mucoepidermoid carcinoma. Adenoid cystic carcinomas are graded based solely on pattern with solid components portending a worse prognosis. Occasionally, adenoid cystic carcinomas may undergo transformation to pleomorphic high grade carcinomas. This feature confers a high propensity for lymph node metastasis and should thus be reported to alert the clinical team. Mucoepidermoid carcinomas are graded in a three tier fashion based on a constellation of features including cystic component, border, mitoses, anaplasia, and perineural invasion among others. All grading schemes are somewhat cumbersome, intimidating and occasionally ambiguous, but evidence suggests that using a scheme consistently shows greater reproducibility than using an intuitive approach. The intermediate grade category demonstrates the most variability between grading systems and thus the most controversy in management. In the AFIP system intermediate grade tumors cluster with high grade tumors, while in the Brandwein system, they cluster with low grade tumors.  相似文献   
80.
目的:研究乳腺囊性增生病中雌激素受体(ER)、孕激素受体(PR)、p53和c—erbB-2表达的临床意义。方法:用免疫组化SP法检测62例乳腺囊性增生病中ER、PR、p53和c—erbB-2表达分布情况。结果:62例患者中ER阴性6例,占10%;阳性56例,占90%。PR阴性7例,占11%;阳性55例,占89%。p53阴性35例,占57%;阳性27例,占43%。c—erbB-2阴性41例,占66%;阳性21例,占34%。结论:乳腺囊性增生病的发生与ER、PR有关,其病变发展与c—erbB-2和p53关系密切,同时也是检测是否癌变的一种实用可靠的方法。  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