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   3371372篇
  免费   242726篇
  国内免费   8592篇
耳鼻咽喉   46516篇
儿科学   112622篇
妇产科学   93255篇
基础医学   473702篇
口腔科学   92788篇
临床医学   306021篇
内科学   662293篇
皮肤病学   78578篇
神经病学   274038篇
特种医学   130464篇
外国民族医学   1282篇
外科学   506863篇
综合类   70066篇
现状与发展   6篇
一般理论   1251篇
预防医学   258744篇
眼科学   76140篇
药学   248196篇
  10篇
中国医学   6814篇
肿瘤学   183041篇
  2019年   26037篇
  2018年   36749篇
  2017年   28150篇
  2016年   32318篇
  2015年   36422篇
  2014年   50260篇
  2013年   75934篇
  2012年   101575篇
  2011年   107722篇
  2010年   64926篇
  2009年   62062篇
  2008年   101071篇
  2007年   107572篇
  2006年   109109篇
  2005年   105056篇
  2004年   101614篇
  2003年   98194篇
  2002年   95077篇
  2001年   161451篇
  2000年   165934篇
  1999年   140400篇
  1998年   40352篇
  1997年   35907篇
  1996年   36097篇
  1995年   34785篇
  1994年   32239篇
  1993年   30214篇
  1992年   110224篇
  1991年   106471篇
  1990年   103444篇
  1989年   99851篇
  1988年   91684篇
  1987年   89942篇
  1986年   84152篇
  1985年   80415篇
  1984年   60132篇
  1983年   50927篇
  1982年   30000篇
  1981年   27067篇
  1979年   53437篇
  1978年   37566篇
  1977年   32048篇
  1976年   29710篇
  1975年   31745篇
  1974年   37393篇
  1973年   35641篇
  1972年   33319篇
  1971年   30720篇
  1970年   28602篇
  1969年   26966篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Since the first transurethral resection of the prostate (TURP) was performed by Guyon at the Necker Hospital in Paris in 1901, this treatment modality has replaced open prostatectomy as the procedure of choice for more than 95% of patients. TURP has been used in surgical treatment of benign prostatic hyperplasia (BPH) and remains the gold standard treatment. Transurethral vapor resection of the prostate (TUVRP) and holmium laser enucleation of the prostate (HoLEP) are new treatment modalities for the treatment of BPH. Each procedure has its own advantages and disadvantages. Availability of instruments, surgical expertise, and specific indications for a particular procedure are of utmost importance for successful outcome, with minimal morbidity. TURP can be either monopolar or bipolar, using thin or thick loop. Bipolar TURP is associated with less bleeding and less chances of dilutional hyponatremia. TUVRP, using a thick wedge loop, causes vaporization and resection of the prostate, and is associated with less bleeding and short operative time. HoLEP is another effective alternative for the surgical treatment of BPH. The holmium laser possesses the ideal combination of cutting and coagulation; however, it has a learning curve.  相似文献   
992.
Background contextLarge, prominent osteophytes along the anterior aspect of the cervical spine have been reported as a cause of dysphagia. Improvement of swallowing after surgical resection has been reported in a few case reports with short-term follow-up. The current report describes outcomes of a series of five patients with surgical treatment for this rare disorder, with a long-term follow-up.PurposeTo study the clinical and radiographic outcomes of a case series of patients surgically treated for dysphagia secondary to cervical diffuse idiopathic skeletal hyperostosis (DISH).Study designRetrospective review of a case series.Patient sampleFive cases from a University Hospital.Outcome measuresClinical and imagenological follow-up.MethodsThe records of five patients with dysphagia who had undergone anterior surgical resection of prominent osteophytes secondary to DISH were reviewed. Extrinsic esophageal compression secondary to anterior cervical osteophytes was radiographically confirmed via preoperative barium esophagogram swallowing study. All patients underwent anterior cervical osteophytes resection without fusion. Postoperatively, patients were followed-up clinically and radiographically with routine lateral cervical radiographs.ResultsPreoperative esophagogram showed that the esophageal obstruction was present at one level in three cases and two levels in two cases. The C3–C4 level was involved in three cases, C4–C5 in three cases, and C5–C6 in one case. There were no postoperative complications, including recurrent laryngeal nerve palsy, wound infection, or hematomas. All patients had resolution of dyphagia soon after surgery (within 2 weeks). Postoperative radiographs demonstrated complete removal of osteophytes. At final follow-up, ranging from 1 to 9 years (average 59.8 months, median 53 months), no patients reported recurrence of dysphagia. Final radiographic examination demonstrated minimal regrowth of the osteophytes.ConclusionsAlthough rarely indicated, surgical resection of anterior cervical osteophytes from DISH causing dyphagia produces good clinical and radiographical outcomes. After thorough evaluation to rule out other intrinsic or extrinsic causes of swallowing difficulty, surgical treatment of this uncommon condition might be considered.  相似文献   
993.
994.

Background  

Cerebral arterial gas embolism is a potentially life-threatening event. Intraarterial air can occlude blood flow directly or cause thrombosis. Sclerotherapy is an extremely rare cause of cerebral arterial gas embolism.  相似文献   
995.
996.
R-mode factor analysis was applied to characterize the chemical composition of human teeth investigated by particle induced X-ray emission (PIXE), Rutherford backscattering spectrometry (RBS) and X-ray fluorescence (XRF) techniques. The approach developed in this study enabled the separation between essential mineral teeth components and the pollutants deposited in teeth tissues during the human life. The three independent sources of metals incorporated in human teeth were found. The first source, representing about 43% of the variance of the concentration data, was characterized by pollutant elements of power industry emissions. The second factor was loaded with toxic elements of general urban pollution. The third factor represented the tooth source as it contained mainly large fractions of the mineral components of the tooth tissue as Ca and K.  相似文献   
997.
998.
Glomeruloid haemangioma is considered a specific marker of POEMS ( p olyneuropathy, o rganomegaly, e ndocrinopathy, M -protein and s kin changes) syndrome and it is usually but not always associated with multicentric Castleman's disease. We report a 78-year-old man who presented with a single, red-violet soft nodule with superficial telangiectases on the scalp. Histopathologically, the lesion consisted of lobules of coiled aggregated capillaries that involved the lumina of dilated vascular structures, mimicking renal glomeruli. A collagenous stroma separated the capillary lobules, and eosinophilic, periodic-acid–Schiff positive globules of varying sizes and shapes were seen within the cytoplasm of endothelial cells. Immunohistochemical studies with antibodies against IgA and IgG, and against the kappa and lambda light chains of immunoglobulins showed immunoreactivity within the eosinophilic globules. Results of complete blood count, liver, renal and thyroid function tests, fasting blood sugar measurement, serum levels of oestradiol, testosterone, prolactin and cortisol, serum protein electrophoresis, immunoelectrophoresis and immunofixation yielded normal or negative results. No Bence–Jones proteinuria was found in a sample from a 24-h urine collection. To our knowledge, only two cases of glomeruloid haemangioma have been previously reported in patients without POEMS syndrome. We describe the third case of glomeruloid haemangioma in a patient without features of POEMS syndrome.  相似文献   
999.
1000.
Background  Nonmelanoma skin cancer (NMSC) has been linked to cutaneous human papillomaviruses of the genus beta (betaPV).
Objectives  We sought to assess the presence of betaPV in NMSC biopsies from a group of Scottish skin cancer patients, both immunocompetent (IC) patients and immunosuppressed (IS) organ transplant recipients.
Methods  One hundred and twenty-one paraffin-embedded skin tumours (27 actinic keratosis, 41 intraepidermal carcinoma, 53 squamous cell carcinoma) and 11 normal skin samples were analysed for the presence of betaPV by a polymerase chain reaction–reverse hybridization assay designed to detect the presence of the 25 known betaPV genotypes.
Results  In IC patients, betaPV was detected in 30 of 59 (51%) tumours and two of 11 (18%) normal skin samples ( P  =   0·046). In IS patients, betaPV was found in 27 of 62 (44%) tumours; no normal skin samples were available for comparison. The most frequently found genotypes were HPV-24, HPV-15 and HPV-38. Of those tumours infected with betaPV, 28 of 57 (49%) were infected with more than one genotype (range 2–8). Tumours from IS patients were from a younger age group (mean age 57·4 years) than IC patients (mean age 73·8 years). Multiple infections were more common in tumours from IC patients (21 of 30; 70%) compared with those from IS patients (seven of 27; 26%) ( P  <   0·001). In the IC group, age did not appear to influence the distribution of single and multiple infections whereas in IS patients the proportion of multiple infections to single infections increased with age. There were no multiple infections in normal skin.
Conclusions  A wide spectrum of betaPV types was detected in our samples. Further characterization of betaPV in vivo is needed in order to determine the mechanisms by which the virus contributes to cutaneous carcinogenesis.  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