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   6749篇
  免费   300篇
  国内免费   35篇
耳鼻咽喉   103篇
儿科学   139篇
妇产科学   82篇
基础医学   884篇
口腔科学   142篇
临床医学   360篇
内科学   1610篇
皮肤病学   222篇
神经病学   516篇
特种医学   256篇
外科学   1199篇
综合类   41篇
一般理论   1篇
预防医学   179篇
眼科学   154篇
药学   298篇
中国医学   11篇
肿瘤学   887篇
  2023年   27篇
  2022年   65篇
  2021年   122篇
  2020年   73篇
  2019年   88篇
  2018年   127篇
  2017年   105篇
  2016年   159篇
  2015年   180篇
  2014年   189篇
  2013年   282篇
  2012年   409篇
  2011年   475篇
  2010年   276篇
  2009年   208篇
  2008年   430篇
  2007年   423篇
  2006年   475篇
  2005年   454篇
  2004年   474篇
  2003年   482篇
  2002年   442篇
  2001年   69篇
  2000年   62篇
  1999年   83篇
  1998年   113篇
  1997年   110篇
  1996年   82篇
  1995年   81篇
  1994年   63篇
  1993年   54篇
  1992年   39篇
  1991年   40篇
  1990年   24篇
  1989年   29篇
  1988年   27篇
  1987年   21篇
  1986年   12篇
  1985年   11篇
  1984年   14篇
  1983年   16篇
  1982年   22篇
  1981年   24篇
  1980年   21篇
  1979年   14篇
  1978年   14篇
  1976年   9篇
  1975年   11篇
  1972年   6篇
  1971年   8篇
排序方式: 共有7084条查询结果,搜索用时 15 毫秒
91.
The management of clival chordoma remains problematic. We present the case of a 48-year-old woman with clival chordoma who underwent multiple surgeries and radiation therapy, including gamma knife stereotactic radiosurgery (GK-SRS), during a 10-year clinical course. The tumor was initially removed by gross total resection via the trans-sphenoidal approach, followed by external linac radiation therapy. The tumor recurred at the clivus 5 years after the initial operation. After repeated trans-sphenoidal removal of recurrent tumors, she twice underwent GK-SRS for a tumor remnant adjacent to the brainstem. Although this part of the tumor was controlled by GK-SRS, there was further tumor extension toward the sphenoid and maxillary sinuses. Ultimately, lower cranial nerve dysfunction developed due to tumor extension into the lower part of the clivus and the patient died of respiratory failure. Autopsy revealed the tumor to extend from the lower clivus to the bilateral middle fossae. The lower part of the tumor extended to the nasal cavity and to the posterior wall of the pharynx, resulting in compression of the upper pharyngeal region. The tumor around the jugular foramen compressed the lower cranial nerves bilaterally. Tumor cells did not, however, invade the intradural space microscopically. Although chordoma is not biologically malignant, this tumor can show massive extension with destruction of bony structures and extracranial invasion of connective tissues. Therefore, the optimal treatment strategy is to remove the tumor mass as extensively as possible, including normal bony structures and connective tissues surrounding the tumor, using skull base surgical techniques.  相似文献   
92.
OBJECTIVE: To assess the functional results, health-related quality of life (QOL) outcomes, and complications in patients with an ileal neobladder in comparison to those with cutaneous diversion (ileal conduit and cutaneostomy). METHODS: Between September 1992 and February 2003, we consecutively performed an ileal neobladder (the Studer method) in 30 patients and cutaneous diversion in 38 patients. In August 2004, questionnaires were mailed to 54 patients. The questionnaire included the validated health-related quality of life (QOL) questionnaire, SF-36 General Health Survey, and a urinary incontinence questionnaire. We also evaluated the functional results in patients with an ileal neobladder and the postoperative complications in patients with both urinary diversions. RESULTS: The data from 41 patients (21 ileal neobladder procedures and 20 cutaneous diversions) were available for the analysis. No differences in the overall QOL were observed between the two groups. Complete daytime and night-time urinary continence was achieved in the 21 patients (100%) and 13 patients (61.9%), respectively. The mean value of the maximum flow rate was 15 +/- 12 mL/min in the 21 neobladder patients. There were 19 early complications in 18 patients (60.0%) and seven late complications in six patients (20.0%) with an ileal neobladder. However, there were 15 early complications in 14 patients (36.8%) and eight late complications in six patients (15.8%) with cutaneous diversions. CONCLUSION: The findings regarding the health-related QOL and the frequency of complications in the neobladder group and those in the cutaneous diversion group were similar. However, the functional results and the status of urinary continence in the neobladder patients were satisfactory.  相似文献   
93.
BACKGROUND: In our institution, spinal anesthesia is the first choice for cesarean section. After the introduction of bupivacaine in 2000 in Japan, the intrathecal anesthetic agent shifted from tetracaine to bupivacaine. We analyzed the anesthesia for cesarean section in recent 7 years and compared the anesthetic quality of tetracaine with that of bupivacaine. METHODS: The anesthetic records were reviewed in the patients who had received cesarean section between January 1998 and December 2004 at our institution. RESULTS:There were 10456 deliveries during the study period with a cesarean section rate of 28.2% (2947 cases). Ninety-one percent of cesarean section was performed under spinal anesthesia. Spinal anesthetic agent shifted from tetracaine to bupivacaine in 2000-2001, both of which was prepared as a hyperbaric solution and supplemented with 0.1 mg of morphine hydrocloride. Of the 2711 patients in whom a cesarean section was started under spinal anesthesia, 20 (0.7%) required conversion to general anesthesia. Three hundred eighteen patients (11.7%) required some analgesic supplementation. The incidence of intra-operative analgesic supplementation was greater in the patients anesthetized with hyperbaric tetracaine and morphine than in those anesthetized with hyperbaric bupivacaine and morphine (22.96% vs 4.20% ; P<0.01). The conversion rate from spinal to general anesthesia for cesarean section was 0.7%. CONCLUSIONS: Comparing these two intrathecal anesthetic agents, the rate of analgesic supplementation in those anesthetized with bupivacaine was lower than in those anesthetized with tetracaine. This suggests that bupivacaine provides the more profound blockade of the visceral pain than tetracaine, and is superior as a local anesthetic.  相似文献   
94.
95.

Background

Colonic interposition is one of the surgical options in children when esophageal replacement is necessary, especially when the stomach is not suitable as a conduit. Conventional open surgery and blind mediastinal dissections present reasonable morbidity, which can be reduced by videosurgery. The authors present novel techniques and the preliminary results of the first series of laparoscopically assisted esophagectomies and colonic interpositions (LECIN) in children.

Methods

Five children aged 19 months to 4 years underwent LECIN. Indications were complicated esophageal atresia and severe caustic esophagitis. The patients were operated on laparoscopically using 3 ports, including the gastrostomy site. Transhiatal esophagectomy was carried out, followed by pyloroplasty and mobilization of the transverse colon maintaining a double blood supply from the left pedicle. The stomach at the gastrostomy site was freed and closed in 3 cases. The colon was exteriorized through this 2- to 3-cm site or through the umbilicus, and the conduit was fashioned extracorporeally, including the colocolic and gastrocolic anastomosis. The colon was pulled up along the retromediastinal tunnel for the coloesophageal anastomosis through a cervical incision.

Results

Operative times ranged from 3 to 4.3 hours; there were no conversions and no complications related to laparoscopy. There were no cardiorespiratory problems, and 4 were extubated immediately after operation. Feedings could be started by day 3 to 4. Postoperative complications included atelectasis (1), pneumonia (1), and cervical stenosis because of persistent fibrotic esophagus, requiring cervical revision (1). One needed dilatations for mild dysphagia. After a follow-up period of 10 to 29 months, all patients are asymptomatic, gaining weight, and feeding well.

Conclusions

These preliminary data suggest that LECIN is feasible and can be safely performed with very low morbidity in children. Further studies with larger series and follow-up are expected.  相似文献   
96.
Degeneration of lumbar intervertebral discs is thought to be a cause of low back pain. Studies have found that a cause of discogenic low back pain is intervertebral disc inflammation and axonal growth of afferent fibers innervating the disc. Lumbar spine fusion for chronic discogenic low back pain is considered an effective procedure. However, no study has investigated the mechanism of pain relief. We did this by applying Fluoro-Gold (FG) to the ventral aspect of the L4–L5 intervertebral discs of 40 rats. We exposed the nucleus pulposus to the annulus fibrosus in a disc punctured model. Rats were divided into 4 groups. Group A: Punctured intervertebral disc with sham posterolateral fusion (PLF) (n = 10), Group B: Punctured intervertebral disc with PLF (n = 15), Group C: Normal intervertebral disc (no puncture) with PLF (n = 10), and Group D: Normal disc (no disc puncture) with sham PLF (n = 5). Four weeks after surgery, bilateral L1–L5 dorsal root ganglia (DRGs) were stained with growth-associated protein 43 (GAP43), a marker of axonal growth, and calcitonin gene-related peptide (CGRP), a neuropeptide marker of pain. Bone union was evaluated using X-ray imaging. Of the FG-labeled neurons, the proportions of GAP43- and CGRP-immunoreactive (IR) neurons in Group A were significantly higher than in Group D (P < 0.05). The proportions of GAP43- and CGRP-IR neurons in bone union rats in Group B were significantly lower than in nonunion rats in Group B and in the rats in Group A (P < 0.05). No significant differences in GAP43- and CGRP-IR neurons were observed between bone union and nonunion rats in Group C and the rats in Group D (P > 0.05). PLF is strongly related to the downregulation of GAP43 and CGRP expression. Therefore, PLF may suppress the increase of inflammatory neuropeptides and the process of axonal growth. Moreover, these results may explain, in part, the mechanism of pain relief following lumbar spinal fusion for chronic discogenic low back pain in humans.  相似文献   
97.

Background  

This study was designed to determine whether gene methylation is a novel diagnostic marker for micrometastasis to the lymph nodes (LNs) in gastric cancer.  相似文献   
98.

Background

Incidence rate of renal cell carcinoma (RCC) differs among countries. The rates of Asian countries are lower than those of countries in North America or Europe but are exceptionally high in Japanese males. Approximately 30% of patients with RCC have metastasis at initial diagnosis, and another 30% have metastasis after nephrectomy. Clinical studies of risk factors in patients with metastatic RCC (mRCC) are mainly based on data from non-Asian patients.

Objectives

We aimed to investigate the prognosis of Japanese patients and their prognostic factors.

Design, setting, and participants

The subjects of this study were 1463 patients who were clinically diagnosed with RCC with metastasis in 40 Japanese hospitals between January 1988 and November 2002.

Measurements

The primary end point was overall survival calculated from first diagnosis of mRCC to death or last follow-up. We also investigated the relationship between survival and clinical features.

Results and limitations

The median overall survival time was 21.4 mo. The estimated survival rates at 1, 3, 5, and 10 yr were 64.2%, 35.2%, 22.5%, and 9.1%, respectively; they contrasted with data from the United States of 54%, 19%, 10%, and 6%, respectively for the same periods. A high percentage of patients had undergone nephrectomy (80.5%) and metastasectomy (20.8%), both of which were shown to prolong survival.

Conclusions

The median survival time in the present study was approximately twice as long as that of previous studies from North America or Europe. Early diagnosis of metastasis, nephrectomy, metastasectomy, and cytokine-based therapy seemed to improve the prognosis of RCC patients in the present study.  相似文献   
99.
Parathyroid hormone (PTH) increases serum calcium (Ca) by enhancing bone resorption and renal Ca reabsorption. However, detailed mechanisms of enhanced bone resorption by PTH remain to be elucidated. Although PTH has been shown to increase the expression level of osteoblastic matrix metalloproteinase (MMP)-13 in vitro, only limited results are available regarding the in vivo regulation of MMP expression. In the present study, we have examined expression levels of MMPs in PTH-infused rats. Infusion of 1.5 or 2.0 nmol/kg/day rat PTH(1–34) for 3 days resulted in a dose-dependent increase in serum Ca. PTH infusion also decreased serum phosphate levels and increased urinary excretion of Ca and phosphate. Infusion of PTH for 7 days resulted in less severe hypercalcemia and hypophosphatemia. Urinary Ca and phosphate excretion in rats infused for 7 days was less than that in rats infused for 3 days. Northern blot analysis showed that PTH infusion increased the expression level of MMP-13 in calvaria, although it did not affect MMP-2 expression. Furthermore, the time-course and severity of hypercalcemia and hypercalciuria correlated with the expression level of MMP-13. In situ hybridization also showed that PTH infusion increased the expression level of MMP-13 in femora. These results indicate that PTH enhances MMP-13 expression in vivo and suggest that PTH stimulates bone resorption at least partly by enhancing MMP-13 expression. Received: June 5, 2000 / Accepted: January 12, 2001  相似文献   
100.
This study analyzes ten cases of malignancy in a cohort of 183 renal transplant recipients, examining surgical management, postoperative immunosuppressive therapy, and long-term outcome. One of these ten patients, who had malignant lymphoma of the jejunum, died of the neoplasm, but the other nine patients did not show any signs of tumor recurrence after removal. All of these nine patients, except for one who had transplant renal cell carcinoma (RCC), received the same dose of immunosuppressive agents after surgery for the malignant disease. Seven patients were still alive at the time of this report, six of whom had good transplant renal function. The findings of this study indicate that even if immunosuppressive agents predispose to the development of cancer, it is not necessary to reduce their dose after removal of the tumor. Received: April 17, 2000 / Accepted: November 20, 2000  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