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   6656篇
  免费   282篇
  国内免费   29篇
耳鼻咽喉   37篇
儿科学   99篇
妇产科学   36篇
基础医学   791篇
口腔科学   178篇
临床医学   384篇
内科学   2005篇
皮肤病学   48篇
神经病学   563篇
特种医学   273篇
外科学   1176篇
综合类   20篇
预防医学   115篇
眼科学   45篇
药学   315篇
中国医学   10篇
肿瘤学   872篇
  2023年   48篇
  2022年   107篇
  2021年   197篇
  2020年   92篇
  2019年   126篇
  2018年   153篇
  2017年   118篇
  2016年   175篇
  2015年   176篇
  2014年   211篇
  2013年   256篇
  2012年   404篇
  2011年   438篇
  2010年   250篇
  2009年   200篇
  2008年   366篇
  2007年   381篇
  2006年   385篇
  2005年   402篇
  2004年   411篇
  2003年   404篇
  2002年   363篇
  2001年   103篇
  2000年   100篇
  1999年   116篇
  1998年   89篇
  1997年   84篇
  1996年   73篇
  1995年   77篇
  1994年   37篇
  1993年   60篇
  1992年   61篇
  1991年   54篇
  1990年   38篇
  1989年   56篇
  1988年   30篇
  1987年   37篇
  1986年   27篇
  1985年   33篇
  1984年   32篇
  1983年   20篇
  1982年   14篇
  1981年   16篇
  1979年   11篇
  1977年   10篇
  1975年   10篇
  1972年   16篇
  1969年   13篇
  1968年   10篇
  1967年   10篇
排序方式: 共有6967条查询结果,搜索用时 0 毫秒
81.
A 46-year-old woman who had received mastectomy for breast cancer 6 years earlier complained of abdominal distension. Computed tomography and ultrasonography revealed massive ascites and ovarian swelling of both sides. She was diagnosed as having primary ovarian cancer and peritoneal dissemination, and underwent a total hysterectomy as well as ovarectomy on both sides. After surgery, she received a sequential chemotherapy, ie, intraabdominal injection of carboplatin (CBDCA 300 mg/m2) and div administration of paclitaxel (PTX 180 mg/m2) as a standard regimen for advanced ovarian cancer. However, detailed histological examinations showed that the ovarian cancer had metastasized from her breast cancer. It is well-known that breast cancer easily metastasizes to the bone, liver, pleura and lymph node, but rarely to the ovarium or peritoneum when chemotherapy is conducted. Therefore, no standard therapy has been established for breast cancer metastasizing to the ovarium. Our patient received 4 cycles of weekly administration of PTX (PTX 80 mg/m2, 3 consecutive weeks, 1-week break), followed by oral administration of doxifluridine+anastrozole on an outpatient basis. No evidence of recurrence of breast cancer has been noted 1 year after surgery. This result suggests that weekly administration of PTX and intraabdominal injection of CBDCA might be beneficial in the treatment of recurrent breast cancer associated with metastatic ovarian cancer and peritoneal dissemination after operation.  相似文献   
82.
PURPOSE: Recombinant adenoviral vectors are widely used in clinical and experimental studies to treat malignant tumors. Recently, host immune responses have been proposed as a major limitation in using adenoviral vectors for repeated gene delivery. We demonstrate another limitation unrelated to host immunity. EXPERIMENTAL DESIGN: We repeatedly transduced an adenoviral vector expressing the human p53 gene (AxCIhp53) into U373MG, a p53-susceptible cell line, and established the AxCIhp53-resistant cell line U373R. Most U373R cells survived even after AxCIhp53 treatment due to reduced transduction efficiency. Expression levels of adenovirus receptors were estimated to investigate the cause of reduced transduction efficiency. The mutant vector was used to overcome the resistance. RESULTS: The transduction efficiency of an adenoviral vector possessing the reporter LacZ gene (AxCAZ2-F/wt) for U373R cells was 25.4-fold less than that for parent cells. The expression levels of integrins alpha(v)beta(3) and alpha(v)beta(5) were found to be decreased in U373R cells without affecting the expression levels of Coxsackievirus and adenovirus receptor. The mutant vector AxCAZ2-F/K20, with a linker and a stretch of 20 lysine residues at the COOH-terminal of the fiber protein, improved the transduction efficiency of U373R cells to 12.6-fold of that of AxCAZ2-F/wt. A mutant vector carrying the p53 gene, AxCAhp53-F/K20, dramatically induced apoptosis in U373R cells. CONCLUSIONS: Glioma cells expressing low levels of adenovirus receptors might survive and proliferate to recur after repeated adenoviral transduction, even if the adenoviral transduction is effective at first. Changing the tropism of vectors is a potent method to overcome resistance.  相似文献   
83.
Tumor blood vessels play an important role in tumor progression and metastasis. We previously reported that tumor endothelial cells (TEC) exhibit several altered phenotypes compared with normal endothelial cells (NEC). For example, TEC have chromosomal abnormalities and are resistant to several anticancer drugs. Furthermore, TEC contain stem cell‐like populations with high aldehyde dehydrogenase (ALDH) activity (ALDHhigh TEC). ALDHhigh TEC have proangiogenic properties compared with ALDHlow TEC. However, the association between ALDHhigh TEC and drug resistance remains unclear. In the present study, we found that ALDH mRNA expression and activity were higher in both human and mouse TEC than in NEC. Human NEC:human microvascular endothelial cells (HMVEC) were treated with tumor‐conditioned medium (tumor CM). The ALDHhigh population increased along with upregulation of stem‐related genes such as multidrug resistance 1, CD90, ALP, and Oct‐4. Tumor CM also induced sphere‐forming ability in HMVEC. Platelet‐derived growth factor (PDGF)‐A in tumor CM was shown to induce ALDH expression in HMVEC. Finally, ALDHhigh TEC were resistant to fluorouracil (5‐FU) in vitro and in vivo. ALDHhigh TEC showed a higher grade of aneuploidy compared with that in ALDHlow TEC. These results suggested that tumor‐secreting factor increases ALDHhigh TEC populations that are resistant to 5‐FU. Therefore, ALDHhigh TEC in tumor blood vessels might be an important target to overcome or prevent drug resistance.  相似文献   
84.

Background

There have been no reports on the incidence, characteristics, treatment outcomes, and prognosis of inoperably advanced or recurrent adenocarcinoma of the esophagogastric junction (AEGJ) in Japan.

Methods

We investigated the clinicopathological characteristics, treatment outcomes, and prognosis for 816 patients with esophagogastric junctional and gastric adenocarcinoma who received first-line chemotherapy between 2004 and 2009.

Results

Of 816 patients, 82 (10 %) had AEGJ. The patients with AEGJ had significantly more lung and lymph node metastasis, but less peritoneal metastasis, than those with gastric adenocarcinoma (GAC). The objective response rate to first-line chemotherapy was 23.3 % for patients with AEGJ and 22.6 % in patients with GAC (p = 0.90). The median survival was 13.0 months in AEGJ and 11.8 months in GAC (p = 0.445). In no patient was tumor site a significant prognostic factor (p = 0.472). In patients with AEGJ, ECOG PS ≥ 2, presence of liver metastasis, and absence of lung metastasis were significantly associated with poor prognosis.

Conclusions

No significant differences were observed in treatment outcomes between advanced AEGJ and GAC. Therefore, the same chemotherapy regimen can be given as a treatment arm in future Japanese clinical trials to both patients with inoperably advanced or recurrent AEGJ and those with GAC.  相似文献   
85.
Lumbar spinal canal stenosis (LSS) is a common spinal disorder among older people. Some LSS patients say that their pain worsens when they lift heavy objects. The Valsalva maneuver is the optimal breathing pattern for producing maximal force. Herein, we present two cases of LSS where the movement of the cauda equina was observed during the Valsalva maneuver.Case Summary: Case 1: A 74-year-old female with a history of LSS presented to our Department of Urology with frequent urination. The patient was diagnosed as having uterine and bladder prolapse. Pelvic cine MRI scan was conducted for detailed evaluation. While the Valsalva maneuver was performed to diagnose pelvic organ prolapses, we observed movement of the cauda equina. Spine MRI and CT, performed one year before presentation, showed severe LSS due to degenerative spondylolisthesis. Case 2: A 73-year-old male underwent radical prostatectomy for prostate cancer. A follow-up cine MRI to confirm urethrorrhea showed the cauda equina moving during the Valsalva maneuver. Moderate LSS due to degenerative spondylolisthesis was retrospectively found on abdominal CT performed before prostatectomy. Conclusion: The findings of our report suggest that movement of the cauda equina during the Valsalva maneuver may be implicated in LSS.  相似文献   
86.
Pleural effusion is a rare manifestation in synovitis-acne-pustulosis-hyperostosis-osteitis (SAPHO) syndrome, which is characterized by the presence of osteoarticular lesions and dermatological involvement. We herein report a 71-year-old man with pleural effusion resulting from SAPHO syndrome. He was successfully treated using corticosteroids and has experienced no recurrence for one year. We should consider SAPHO syndrome when encountering cases of anterior chest pain and pleural fluid.  相似文献   
87.
88.
Fogging of the thoracoscopic lens affects a surgeon’s ability to maintain a clear operating field. In uniportal video-assisted thoracoscopic surgery, the thoracoscopic lens tends to fog when the surgeon does not hold a suction instrument. Thus, a suction instrument needs to be held by the surgeon’s nondominant hand to remove surgical smoke, mist, and moisture. Here, we describe a simple, easy and cost-effective surgical smoke ventilation technique for uniportal video-assisted thoracoscopic surgery using a suction catheter to solve the problem. We present this technique and comment on its advantages, including decreased cost and improved surgical visualization.  相似文献   
89.
Therapeutic peptide and protein drugs have high specificity and activity in their functions but present challenges in their administration route, requiring development of new delivery systems to improve their bioavailability. The aim of this work was to investigate the role of N-trimethyl chitosan- (TMC-) coated liposomes in the oral administration of calcitonin. TMC with a degree of quaternization around 78% was synthesized and its mucoadhesive properties were examined in vitro using the mucin-particle method, which confirmed that TMC showed mucoadhesion comparable to that of chitosan. TMC-coated liposomes containing calcitonin were prepared and characterized as having a particle size of 262 nm, zeta potential of 35.8 mV and high entrapment efficiency (89.1%). The in vivo evaluation of mucoadhesion was carried out using confocal laser microscopy to observe the residence time and permeation extent after intragastric administration. The results showed that TMC-coated liposomes prolonged the residence time and increased the penetration effect of the liposomal system compared to non-coated liposomes. The study of pharmacological effects confirmed that TMC-coated liposomes increased the area above the blood calcium concentration-time curves (AAC) from 3.13?±?20.50 to 448.84?±?103.56 compared to the calcitonin solution. These results support the feasibility of TMC-coated liposomes as a new oral delivery system for peptide and protein drugs.  相似文献   
90.
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