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   1374篇
  免费   213篇
  国内免费   1篇
耳鼻咽喉   10篇
儿科学   29篇
妇产科学   37篇
基础医学   125篇
口腔科学   43篇
临床医学   237篇
内科学   338篇
皮肤病学   9篇
神经病学   159篇
特种医学   18篇
外科学   135篇
综合类   8篇
一般理论   1篇
预防医学   246篇
眼科学   18篇
药学   66篇
肿瘤学   109篇
  2024年   6篇
  2023年   45篇
  2022年   24篇
  2021年   41篇
  2020年   45篇
  2019年   35篇
  2018年   59篇
  2017年   64篇
  2016年   66篇
  2015年   43篇
  2014年   67篇
  2013年   87篇
  2012年   88篇
  2011年   69篇
  2010年   61篇
  2009年   66篇
  2008年   66篇
  2007年   73篇
  2006年   64篇
  2005年   64篇
  2004年   54篇
  2003年   42篇
  2002年   37篇
  2001年   51篇
  2000年   31篇
  1999年   17篇
  1998年   18篇
  1997年   10篇
  1996年   19篇
  1995年   14篇
  1994年   10篇
  1993年   16篇
  1992年   13篇
  1991年   10篇
  1990年   9篇
  1989年   12篇
  1988年   4篇
  1987年   13篇
  1986年   9篇
  1985年   5篇
  1984年   8篇
  1983年   3篇
  1982年   5篇
  1979年   7篇
  1978年   2篇
  1977年   2篇
  1975年   2篇
  1968年   4篇
  1967年   3篇
  1945年   6篇
排序方式: 共有1588条查询结果,搜索用时 20 毫秒
81.
The ability to understand how Parkinson's disease neurodegeneration leads to cortical dysfunction will be critical for developing therapeutic advances in Parkinson's disease dementia. The overall purpose of this project was to study the small‐amplitude cortical myoclonus in Parkinson's disease as an in vivo model of focal cortical dysfunction secondary to Parkinson's disease neurodegeneration. The objectives were to test the hypothesis that cortical myoclonus in Parkinson's disease is linked to abnormal levels of α‐synuclein in the primary motor cortex and to define its relationship to various biochemical, clinical, and pathological measures. The primary motor cortex was evaluated for 11 Parkinson's disease subjects with and 8 without electrophysiologically confirmed cortical myoclonus (the Parkinson's disease + myoclonus group and the Parkinson's disease group, respectively) who had premortem movement and cognitive testing. Similarly assessed 9 controls were used for comparison. Measurements for α‐synuclein, Aβ‐42 peptide, and other biochemical measures were made in the primary motor cortex. A 36% increase in α‐synuclein was found in the motor cortex of Parkinson's disease + myoclonus cases when compared with Parkinson's disease without myoclonus. This occurred without significant differences in insoluble α‐synuclein, phosphorylated to total α‐synuclein ratio, or Aβ‐42 peptide levels. Higher total motor cortex α‐synuclein levels significantly correlated with the presence of cortical myoclonus but did not correlate with multiple clinical or pathological findings. These results suggest an association between elevated α‐synuclein and the dysfunctional physiology arising from the motor cortex in Parkinson's disease + myoclonus cases. Alzheimer's disease pathology was not associated with cortical myoclonus in Parkinson's disease. Cortical myoclonus arising from the motor cortex is a model to study cortical dysfunction in Parkinson's disease. © 2011 Movement Disorder Society  相似文献   
82.
83.

BACKGROUND.

The ThinPrep Imaging System (TIS) has been approved by the U.S. Food and Drug Administration for use to decrease the number of false‐negative results in ThinPrep (TP) gynecologic specimens and increase cytotechnology productivity. Although the increased detection of squamous abnormalities using the TIS has been well documented, to the authors' knowledge, data regarding the impact of the TIS in the detection of glandular abnormalities is limited. The goal of the current study was to evaluate the effectiveness of the TIS in detecting glandular abnormalities in cervicovaginal specimens.

METHODS.

TIS evaluated TP tests with histologic confirmation of adenocarcinoma involving the gynecologic system were included in the current study. Two cytotechnologists independently reviewed the cases for the presence or absence of atypical glandular cells. Review results were correlated with initial cytologic and histologic diagnoses.

RESULTS.

A total of 124 cases met the criteria for inclusion in the current study. Seventy of these cases (56%) were found to contain atypical glandular cells on the TP slide. TIS was able to identify atypical cells in 97% of these cases (68 of 70 cases). Nine cases initially reported as benign were found to contain atypical glandular cells on secondary review. All but 1 of these cases contained atypical glandular cells detected by the TIS. The majority of these false‐negative cases (6 of 9 cases) derived from endometrial adenocarcinoma. No cytologic evidence of a glandular abnormality was found in the 54 remaining cases.

CONCLUSIONS.

The TIS was found to be effective in identifying atypical glandular cells in specimens containing malignant glandular cells, leading to a full review of the slide. Cancer (Cancer Cytopathol) 2008. © 2007 American Cancer Society.  相似文献   
84.
Ultrasonographic features of a fetus at 18 weeks of gestation suggesting a body stalk anomaly are presented. These included a large abdominal anterior wall defect in apparent continuity with the placenta, severe kyphoscoliosis of the lower spine, the absence of one kidney, and a very short umbilical cord with only one umbilical artery. The amniotic fluid was reduced and the fetus was almost immobile at short-interval ultrasound examinations. The pregnancy was terminated and autopsy of the fetus showed abnormalities compatible with maldevelopment of both cephalic and caudal embryonic folds.  相似文献   
85.
The authors show that prismatic adaptation can reduce tactile inattention in stroke patients with unilateral neglect. Four patients with visuospatial neglect and tactile extinction underwent 10-minute application of 20 degrees right-shifting prismatic lenses during pointing. This improved contralesional tactile perception in all patients, even for a task requiring no exploration or spatial motor responses. This finding suggests a potential role for prismatic adaptation in the rehabilitation of multiple sensory modalities in patients with neglect.  相似文献   
86.
Self-report measures of sexual violence that ask women whether they have experienced threats of physical violence have attracted criticism in recent years; detractors claim that these measures lead researchers to overestimate the prevalence of sexual violence. Our study explored this issue by collecting data on the prevalence of threats versus force in the context of sexual aggression. Female undergraduates at two universities (n 1 = 69; n 2 = 111) were asked about their experiences with sexual coercion using a revised version of the Sexual Experiences Scale (Koss and Gidycz, 1985). Four of the original items were modified to distinguish between sexual contact that occurred as a result of a perpetrator using physical force and sexual contact that occurred because a perpetrator threatened physical violence. Analyses of the revised items revealed that the use of physical force was at least as likely as threats and that for some types of sexual acts, physical force was actually more likely than verbal threats. Furthermore, prevalence figures for three of the four types of sexual acts considered were not significantly altered by collapsing threat of force with use of force. Implications for future research on women's experiences of sexual coercion are discussed.  相似文献   
87.
A 10-year-old boy presented with a 5-month history of recurrent abdominal pain, fever, and jaundice. Ultrasound examination revealed a thick-walled gallbladder and dilatation of the biliary tree. Endoscopic retrograde cholangiography showed irregular common bile duct dilatation. After cholecystectomy for acalculous cholecystitis, histological examination of the operative specimen revealed the features of xanthogranulomatous cholecystitis. The abnormalities observed in the bile duct were secondary. This unusual destructive inflammatory process has previously only been described in adults.  相似文献   
88.
To enhance the immunogenicity of nucleic acid vaccines, we used plasmid DNA vectors that contained replicons derived from the prototype alphavirus, Sindbis, and another alphavirus, Semliki Forest virus. When transfected into cells or injected directly into animal muscle, these plasmids launch a self-replicating RNA vector (replicon) which in turn directs the expression of a model tumor antigen. Immunization with plasmid DNA replicons elicited immune responses at doses 100 to 1000-fold lower than conventional DNA plasmids and effectively treated mice bearing an experimental tumor expressing the model antigen. Significantly, replicon-based DNA plasmids did not produce a greater quantity of antigen; instead, antigen production differed qualitatively. Plasmid DNA replicons mediated antigen production that was homogeneous in all transfected cells and associated with the apoptotic death of the host cells. Because of their safety and efficacy, plasmid DNA replicons may be useful in the development of recombinant vaccines for infectious diseases and cancer.  相似文献   
89.
OBJECTIVE: Tumor angiogenesis is believed to be a prognostic indicator associated with tumor growth and metastasis. Studies of angiogenesis in breast, prostate, and lung cancer, as well as melanoma, have shown that neovascularization correlates with the likelihood of metastasis and recurrences. The purpose of this study was to evaluate microvessel density as a prognostic factor in endometrial cancer. METHODS: Between 1980 and 1991 the tumor registry identified 25 patients with a diagnosis of recurrent endometrial cancer. These patients were matched with 25 patients with nonrecurrent disease for age, stage, grade, and treatment. The histologic slides of the 50 patients were reviewed. The paraffin blocks were obtained, and the area of the deepest myometrial invasion was selected for staining. The microvessels within the invasive cancer were highlighted by means of immunocytochemical staining to detect factor VIII - related antigen. Microvessels were counted by two investigators who were blinded to the patients' clinical status. Survival data were analyzed with Kaplan-Meier survival curves. RESULTS: Microvessel count was related to likelihood of recurrence, although this trend did not reach statistical significance. Patients with tumors of low capillary density had a mean survival time of 123 months. Patients with tumors of high capillary density had a mean survival time of 75 months (p = 002). Among patients with recurrent disease, those with a low capillary count survived a mean of 64 months. Patients with recurrent disease with tumors of high capillary density survived a mean of 45 months (p = 0.002). CONCLUSION: Angiogenesis factor correlates with survival in endometrial carcinoma. (Am J Obstet Gynecol 1996;174:1879-84.)  相似文献   
90.
AIM: To determine whether elective laparoscopic appendicectomy is justified for chronic right iliac fossa (RIF) pain of undetermined origin. METHODS: A retrospective audit of all laparoscopic appendicectomies between January 1997 and August 2003 was performed. The expanded medical audit system (EMAS) and a Microsoft Access database of operative records were used to identify patients with chronic RIF pain subjected to elective appendicectomy. Case notes were retrieved and analysed for patient profile, duration of symptoms including clinic visits and admissions, operative findings, histological analysis, and postoperative performance. A correlation between histological findings and final outcome was investigated. RESULTS: Ninety-eight patients underwent laparoscopic appendicectomy during the period of the study. A total of 11 cases with chronic RIF pain were identified. Nine were female and 2 male. Age ranged from 9 to 14 years with a mean of 11.9 years. The number of clinic visits and admissions for chronic RIF pain ranged from 2 to 8, with a mean of 4. Duration of symptoms ranged from 1 to 36 months, with a mean of 12.1 months. Detailed history, clinical examination, and serological and radiological investigations failed to reveal the cause of the pain in all cases. Patients were followed up in postoperative clinics for between 1 and 72 months, with a mean of 16.1 months. Histology of resected appendices showed acute inflammation (3 cases), fecoliths (2 cases), lymphoid hyperplasia (LH) (1 case), LH and a foreign body reaction (1 case), LH and mucosal hyperplasia (1 case), and Enterobius vermicularis parasites in 1 case. The appendix was normal in 2 cases. Eight patients had complete resolution of RIP pain. Seven of these had pathology within the appendix and 1 was histologically normal. Two patients with resolved RIF pain, but with pain elsewhere, had lymphoid hyperplasia noted within the appendix. One patient with persistent pain 6 years postoperatively had a normal appendix. CONCLUSION: This study demonstrates that a significant number of patients with chronic RIF pain have pathology within the appendix. The majority of these cases will benefit from elective appendicectomy. It is critical however that all other possible causes of pain in the RIF are excluded. Laparoscopy is an integral part of the diagnosis and management of this particularly difficult group of patients.  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